This was first posted 1/3/2010 and is herein posted once again. My big question is, what the hell is with the saucer design for interstellar travel? Saucers have a large surface to volume ratio which inherently restricts the size of everything they would have to bring along. Don’t they have food and luggage to pack? The same argument holds even if they are tiny buggers. This line of investigation will have to wait for another post.
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Imagine that you and a companion are out for an evening stroll after a big dinner, say in a park somewhere. You hear a curious whining sound and look up to see an alien spaceship on a landing approach to the park. The craft lands and the crew scuttles off to perform some tedious abduction or organ harvest in the neighborhood.
Your companion exclaims “Golly! There is something you don’t see every day!”. But you’re unmoved by your companions incisive commentary. Because you see this as a long sought opportunity to examine an alien craft up close.
What would you look at? The propulsion system? Or perhaps the weapons array or guidance system? Pffft.
I would look at something much more mundane. I think it would be very enlightening to see what kind of fasteners they use. That’s right. Fasteners. Nuts, bolts, latches, bungees, straps, nails, hinges, hooks & loops, and rivets. How do these confounded exo-buggers hold things together? What’s the deal?
Fasteners are mechanical contrivances used to restrain objects into a desired configuration, often by the application and fixing of tension or compression through some structural element. Think of all of the fasteners we encounter before we set foot out the door every morning.
Elastic articles of clothing perform a fastening function through the application of tension about numerous body parts through the miracle of Spandex/Lycra. Shoe laces are fastening devices that apply and hold tension on opposing shoe upper elements wrapped over the arch of the foot.
Moving upwards, the zipper is a fastener that works in concert with a trouser/skirt button or snap fastener. The belt and buckle are a fastener ensemble that together apply and hold tension about the circumference of the waist to keep ones trousers from succumbing to the pull of gravity.
Other fasteners include shirt buttons, brassiere connectors (damn those things!), earring wires, eyeglass frames (they connect to your face), cell phone belt attachments, the deadbolt on the front door, all manner of electrical connectors, and the list goes on and on. Electrical connectors are especially interesting because they combine the functions of electrical continuity and fastener. All are a compromise between the competing interests of biomechanics, convenience, safety, regulatory standards, and custom.
So, back to the space ship. How would space faring beings approach the problem of fastening materials and components. Would they use individual components fastened together or would they use integrated component assemblies that support multiple functions? Perhaps the mechanical fastener question is moot because components would be cast, glued, or welded.
Integrated components have a certain appeal, but, by their integrated nature could serve as a node from which to initiate failure propagation to multiple systems. For instance, if a battery was built to serve as a structural element for the craft, could a battery failure of some sort serve to initiate a structural failure mode? At what point is it foolish to integrate systems rather than leave them distributed? As always, it depends.
I think an alien spacecraft would have at least a few kinds of obvious fasteners. Surely alien technologies are subject to component failures and would require occasional repair. Of interest would be the concessions to alien biomechanics.
Humans occasionally use wingnuts to fasten objects that need not be permanently affixed. The wingnut is simply a style of threaded nut that has two modest protuberances that allow for torsion and compression to be applied by the fingers and wrist. The wingnut is not functional for beings who lack the sort of articulated digits that we have. Perhaps an alien being would have a latch or other contrivance to accommodate its appendages.
Of course, all of this alien talk is just a device with which to cast the matter of fasteners into a more interesting light. Fasteners are part of our collective technological heritage and are rather under-appreciated. But, if you are unfortunate enough to be abducted by aliens, I suspect that the matter of alien fasteners might be of immediate interest.
A paper is out comparing the resources needed to send women vs men on a trip to Mars. The paper, appearing in Nature publication Scientific Reports is: Scott, J.P.R., Green, D.A., Weerts, G. et al. Effects of body size and countermeasure exercise on estimates of life support resources during all-female crewed exploration missions. Sci Rep13, 5950 (2023). https://doi.org/10.1038/s41598-023-31713-6.
The paper is worth a look, but I’ve cut and pasted the conclusions below-
When compared at the 50th percentile for stature for US females and males, these differences increased to − 11% to − 41% and translated to larger reductions in TEE, O2 and water requirements, and less CO2 and Hprod during 1080-day missions using CM exercise. Differences between female and male theoretical astronauts result from lower resting and exercising O2 requirements (based on available astronaut data) of female astronauts, who are lighter than male astronauts at equivalent statures and have lower relative VO2max values. These data, combined with the current move towards smaller diameter space habitat modules, point to a number of potential advantages of all-female crews during future human space exploration missions.
A female crew would require less energy and less weight in provisions than men just from the benefits of smaller scale metabolism alone. Looks like hurtling women to Mars is an all-around winning idea.
Malcom Gladwell recently wrote a short essay titled “What I Found at a Mennonite Wedding”. While I don’t hold the iron age theory of the universe that the big religions have, I have always admired groups like the Quakers who practice simplicity and humility. Gladwell relates the idea of “power distance” that he observes at the Mennonite wedding he attended.
Power distance is an anthropological concept developed by psychologist Geert Hofstede. According to Wikipedia, this refers to “inequality and unequal distributions of power between parties“. Somewhat later the term was further refined by the Global Leadership and Organizational Behavior Effectiveness (GLOBE) project. GLOBE defined power distance as “the degree to which members of an organization or society expect and agree that power should be shared unequally”.
Once you see the definition, it’s meaning seems obvious. The phenomenon appears where individuals and groups seek control over others. It relies on the natural inclination of people to go along to get along or to seek affiliation. The recent MAGA love affair with president #45 carries the distinct smell of a public willing to turn more power over to a single person- the extension of power distance. It happened with Putin, Stalin, Hitler, Mussolini, and others.
The connection to the Mennonite wedding is that the wedding party themselves served up lunch to the guests. This is a power distance shortening action meant to recognize and serve the guests as part of the community.
Some people criticize Gladwell for being just a bit shallow in his writings. He seems to write the view from 5,000 ft rather than from an alligator’s viewpoint in the swamp. There is a place for generalization … if you want readers, that is.
I saw the words “thoriated tungsten” somewhere in the literature and became curious as to what brought these two metals together. Before I get to thoriated tungsten, I’ll give a little background on tungsten and filaments made from it. There is a surprising amount of art and science in tungsten filaments. Tungsten filaments split into two broad applications- illumination and thermionic emission.
I’ve been curious about the effect of surging LED lighting demand on the tungsten filament business and tungsten demand overall. Naively, I guessed that there might be a noticeable effect on tungsten demand. A Google search only turns up people who want to sell a market research document. One of these web sites claims that demand for tungsten is expected to nearly double from 2021 to 2029 from $4.41 Billion to $7.56 Billion. The major demand for this metal is from the mining and drilling industries in the form of tungsten carbide cutting tools. The major producers of tungsten are China, Russia, Portugal, Austria and Bolivia, with China producing the vast majority.
All have a +2 cation and the tungstate -2 oxyanion. The WO4-2 tungstate anion has tetrahedral geometry similar to sulfate and can also form polyoxotungstates with octahedral WO6 geometry. Polyoxotungstates can form clusters by the sharing of octahedral oxygens similar to silicates. A large number of interesting polyoxotungstates have been identified.
Tungsten filament- a coil of coils.
Tungsten turned out to be a perfect choice for light bulb filaments due to it high melting point and its mechanical integrity at high temperature. The coiled coil filament design proved to be much superior to a single coil or a straight filament. Below is a picture found at this website showing the illumination differences in the 3 configurations of the tungsten element. The difference in filament geometry is striking.
The photo above shows a 240 VAC 60 Watt bulb where a coiled coil has been uncoiled to produce a single coil section and a straight section. The whole coil is there. Light bulbs are filled with a mixture of inert nitrogen and argon at below atmospheric pressure. A coil allows a greater length of tungsten wire to be easily placed in the bulb and a coil of coils even more so. During operation the filament suffers heat losses by conduction and convection of the bulb gases. The primary coil and the coil of coils serve to reduce exposure of the filament to the cooling gas flow. The coil provides some self-heating due to the proximity of the coil to itself. It intercepts some of the radiant energy and heats further. In the coil of coils, this effect is much more pronounced as seen in the picture above. The Lamptech website containing this photo is well worth a visit.
As mentioned above, one advantage of using tungsten as a filament is that it has an extremely high melting temperature of 3422 oC (3695 K). This allows the filament to be heated to very high temperature with the resulting blue shifted black body curve (above), This allows the spectrum to be brighter in the shorter wavelengths and consequently less reddish to the eye than a lower temperature filament. Wiens Law is the basis of color temperature.
When you shop for LED light bulbs, you might notice that LED bulbs are rated on the basis of color temperature. The lower the color temperature, the more yellow/red the light will be. The higher the color temperature, the more whitish the light will be.
However, with high operating temperatures a filament can evaporate, removing mass and robustness. Tungsten filaments, among others, are susceptible to this mode of failure. Another mode of failure occurs when a tungsten filament is hung vertically. Convection of the hot gasses in the bulb causes the top of the filament to get hotter and fail sooner. You’ll notice that lamp filaments tend to be strung horizontally.
Why tungsten halogen? Over time a tungsten filament will evaporate enough tungsten to blacken the bulb and become fragile. The presence of a halogen vapor in a light bulb causes a reaction between the tungsten and the halogen leading to redeposition of the tungsten back to the filament. However, this process requires higher bulb envelop temperatures, i.e., >250 oC. I have to assume that the small size of halogen lamps is to assure that the bulb temperature remains high for the tungsten-halogen recycle.
Thermionic Emission
Tungsten filaments in light bulbs is an application familiar to everyone. But there is another important use of tungsten filaments. The production of electron emission from filaments has been in use for a very long time. A hot filament or other hot surface under vacuum can be made to produce electron beams that can be accelerated or deflected and focused to do useful things. The electron beams can be made to carry modulated signals that can be put to use in detecting or radiating radio signals for radio, television or a myriad of other uses. The old vacuum picture tubes in early television used a filament to generate an electron beam that could be directed to scan across a phosphor coated surface to produce moving images.
What caught my attention when sorting through the tungsten literature was the mention of thoriated tungsten filaments. This topic goes back to the 1920’s with Irving Langmuir. In 1923 he published a paper in Physical Review Langmuir found that the rate of electron emission from 1 to 2 % thoriated tungsten to be “it was discovered that by suitable treatment the filaments, containing 1 to 2 per cent of thoria, could be activated so as to give an electron emission many thousand times that of a pure tungsten filament at the same temperature.” He found that the efficiency and life of a tungsten filament could be extended by spiking the tungsten with thorium oxide. He postulated that thorium is reduced and migrates to the surface of the tungsten filament forming at most an atomic monolayer. Thermionic emission occurs when a hot object like a filament evaporates electrons.
Every substance has work function energy in eV that is required to remove an electron from a surface. Additives to tungsten like lanthanum, cerium or thorium or their oxides have a lower energy work function than does tungsten and will produce a greater flux of electrons. This even applies to TIG welding where an electric discharge must jump across a workpiece and a sharpened tungsten rod.
A 1-2 % thoriated tungsten welding rod or filament will allow thorium to migrate to the surface via grain boundaries while in operation and deposit on the surface. The work function energy of thorium is lower than that of tungsten, so the thoriated surface can release more electrons at a given temperature.
Oh no! Is this another gush of Too Much Information that no one really wants to hear? I guess it could be. As it happens, I’ve accumulated a lifetime of insights into depression that could be lost if I happen to suddenly fall over dead. It would be a shame to not pass it along, so here goes.
Background
It dawned on me some time ago that much of the emotional agony I experienced as a young child seems to have been early manifestations of what would be a lifetime of struggle with depression. Except for a parental divorce when I was ten, I had a normal rural pre-teen upbringing in the vast corn and soybean fields of Iowa. Summers were hot and sticky and winters were extremely cold. We had vast pastures and river banks to explore and badgers to watch out for. We detassled corn and pulled weeds by hand in the bean fields for a few weeks every summer. Field labor was not my favorite thing.
It was the 1960’s and black-and-white television was full of news about the space race and the crazy hippies and Viet Nam. Hippies were using drugs and rioting, astronauts in cool spacesuits were riding capsules into space and F-4 Phantoms were flying and sometimes crashing in Viet Nam. This was the frame of reference of the time.
I was pretty lucky as the eldest of 5 kids. Despite the divorce of my parents and all the upset that goes along with it, we had wonderful grandparents. They stepped in and provided considerable care and comfort in our lives. While this family upset was an aggravating factor in my depression, it wasn’t at the root of it. There was something more fundamental to it.
Everyone experiences dark periods in their lives that somehow expire and normal emotional being returns. I had episodes of this as well and they would subside. Growing up has its ups and downs, learnings and misunderstandings. What began to happen was that these dark periods would last for weeks and months with no obvious triggers that set it off. Those around me couldn’t understand why the darkness persisted in a kid who outwardly had nothing to be sad about.
Added to this was the fact that I had no natural athletic abilities other than dashing to get out of the way and no interest in sports. My family was in a quandary about what to do with a boy who didn’t like sports. This contributed to social isolation that, frankly, I enjoyed. Solitude was something that I craved but got only too infrequently. I still crave solitude.
Jumping ahead on the timeline
Depression is a state where you lose hope, ambition, social contact, interest, energy and sometimes even the will to live. It is a potentially deadly condition that deserves attention by medical professionals. There is talk therapy, drug therapy and probably a few other things I’m unaware of. Speaking for myself only, talk therapy helped me to get a greater understanding of the condition itself, but really not much else of lasting effect. I still got and remained depressed. I needed drugs.
I have been trying various antidepressants since the late 1970’s with unequal success. I started with imipramine at age 19 but it made me sleepy and inattentive with dry mouth so I eventually decided to quit using it. It is a tricyclic antidepressant introduced in 1957 and was prescribed by a general practice MD. Deciding to discontinue drug therapy is a common problem practiced by many depressed individuals and I did the same numerous times.
I managed to get into college and get a BA in chemistry without antidepressants. However, in grad school I went back to drug therapy with Prozac and Paxil. After some dosage adjustments I found it to be very helpful for a while. Eventually my depression overwhelmed the drug. What I eventually realized was that I was in a situation that was very stressful even without depression. My depression was aggravating my situation which was grad school which was amplifying the depression. There was a feedback loop. I needed to self-actualize. I needed a major achievement giving me more control over my life. I wanted to be a chemistry prof.
I finished grad school and went on to a 2-year postdoc. Unfortunately, my marriage failed a few months into the move to Texas and my postdoc. Suddenly I was alone in a large Texas city with no vehicle and a very low paying job. Texas being Texas, there was no decent public transportation so I spent a good deal of time walking and thinking in the miserable heat and humidity.
One day as I began my morning walk to the university lab where I worked my mood started out … normal. Halfway there my mood began to darken abruptly as though a curtain dropped blocking the light. I had nothing depressing on my mind that might have triggered it. The light of a normal mood state just extinguished.
This continued for many months. I again went to a general practitioner MD and he put me on lithium. I took this for 2 months. It did absolutely nothing other than to make me dizzy. At least I wasn’t manic depressive. I went off it and found a shrink across the city for help. He took a lot of notes over many sessions and never spoke. I talked and he listened. Eventually he said that he wanted to prescribe an MAO inhibitor. He handed me a prescription. Back at the university I did a deep dive on this class of medications to see what they were about. I concluded that, given the many risks and side effects, there was no way I’d take this. Never went back to that shrink again.
Years later, after enduring the depression over a 5 year career in teaching, I got an industry job. The company folded 10 months after I arrived so I went to work in construction to feed the family while searching for another chemistry job. I got the chemistry job and worked for about 10 years while on Prozac and other SSRI’s. But eventually the depression had become unmanageable with the meds I was taking. My family doc gave up and made some suggestions about what to do. It turned out that he had depression too and left medicine.
Eventually I found a shrink who ended up being quite good. This time there was titration involved. We spent a year or two fine tuning a mix of medications. What worked was the combination of bupropion and escitalopram. I eventually figured out that a large part of what I had thought of as “just” depression in fact had an element of uncontrolled anxiety to it. The medications I was taking did nothing for the anxiety. Bupropion has been shown to have beneficial effect on anxiety associated with depression.
But something unexpected happened. My anxiety was suppressed so deeply that I wasn’t worrying about much of anything. A person needs to have enough anxiousness to stay on top of life’s challenges. We made an adjustment in dosage and things are now fine.
Things I’ve noticed that are helpful
Get the right help early. Family practice docs can only go a short distance into treating depression. Mine eventually gave up and handed me a list of shrinks. It worked, but only after I was way down the timeline.
Well intended folks may suggest alternative medicines or greater religious devotion. I’ve never found these things persuasive or useful.
Sometimes talk therapy or attitude changes just do not work. Don’t feel bad if they do not work for you.
Exercise can be very helpful.
Reclusiveness is an effect of depression. I’m still not over this part.
Don’t pay attention to famous scientologists who talk down drugs. They’re idiots.
A shrink is a physician who has specialized in psychiatry. Psychiatry today is substantially about medication. These folks have a deep understanding of the pharmacology of the different meds and what constitutes reasonable expectations.
Depression meds may not fix basic personality issues. If you’re an asshole while you are depressed, you could still be one when you are better.
Finding better help may seem difficult. You have to reach out and contact people which may be undesirable. You might be unduly pessimistic about the benefits of finding a shrink. It’s like digging a tunnel into rock. You have to keep showing up and swinging the pickaxe against the wall. Eventually you’ll get through.
The source of your depression and anxiety may be more than just brain chemistry. Your life situation might be genuinely awful as well. Fighting depression may require that you change how you are living and who you are around. Some people are toxic and a greater distance from them may be needed.
A course of self-improvement can be helpful as well as a change in living arrangements.
Avoid suicide. It might seem like the fastest way out of the pain, but it really is a permanent solution to a temporary problem**. Also, your suicide is likely to be the main thing people will remember about you. You wouldn’t want that.
Depression can get worse as we age. Be aware of this.
The world is truly a beautiful place full of wonders to discover. Dive in. Be curious.
** The phrase “permanent solution to a temporary problem” is admittedly a bit pollyannish. This would be of no comfort to someone in a death camp or gulag. While not words of universal relevance, I must assume the Dear Reader and a great many others are not in a death camp. While not useful advice to everyone, it still applies to a large number of people.
Wow. This gives me chills. In the last week this blog has been visited twice by chatgpt-content-generator.online. If AI is getting content from me, what other crazy sh*t are they retrieving?
I really want to blather on about the Fox talking head Tucker Carlson and how he got himself dumped from his network. But that would be indecent self-indulgence. Instead, I’ll just bathe in the warm glow of schadenfreude.
Along with the fact that #45 is running for president again is the sickening prospect of two more years of news coverage of his orange face spewing streams of lies, exaggerations and deflections. Broadcasters and news providers in all media can’t resist the bloviating #45 because he attracts admiring eyeballs and those enchanted by the freakish spectacle of human idiocy at its worst.
As bad as the prospect of #45 returning to the White House is the reality check that a large block of the voting public will vote for him again. After 6 years of shameful behavior and nauseating political drama, it is quite clear that most in the MAGA crowd are not put off by his behavior.
A vote for #45 the isolationist is a vote for instability in Europe. Czar Putin will see to it that recovery of former Soviet states will happen. The US cannot be isolationist as Russia executes its land grab. At this period in history, western isolationism by passive acceptance of Russian expansionism is a one-way ticket to Russian authoritarian hegemony. This is an end state that we in the west should be able to agree on.
The world has learned that Russia’s conventional land forces are not so formidable. This is the unexpected downside of the invasion for Putin. However, Russia has always considered that the use of nuclear weapons is part of a continuum rather that preceded by a firebreak as with the west. The Russian talking heads have been keen to remind us of the power of their nuclear triad. Little mention is made of the US nuclear triad that more than matches it. The presence of nuclear sea launched ballistic missile submarines on both sides alone renders a nuclear conflict as suicide for both sides.
Americans should go to YouTube and find translated video of Russian talking heads spewing the most vile hate speech you can imagine at the Ukrainians and western powers. Polish public television TVP is a good place to start. Many Russian talking heads are speaking in favor of an all out war with the west, including nuclear weapons. Many claim that WWIII has already begun. We have been reduced to non-human beasts deserving of painful death for daring to push back Russian efforts to expand their great empire. Some figures claim that the west is after their oil & gas resources.
The reason I suggest viewing this content is to understand the constant high intensity of their internal propaganda. While there is some open criticism of the military, criticism of Putin himself is religiously avoided. Many say that Putin is surrounded by incompetent people. This is the information environment that the Russian people are subject to on a daily basis. It is difficult to believe that Russian citizens will rise up to overthrow the Putin regime through some kind of a democratic effort. More likely someone around Putin will take over with his blessing.
Russian propaganda is not some side specialty that issues from an office somewhere in Moscow. It is built into the whole governing apparatus and supervised by the GRU. Russia is very effective at not only generating fake news, but also mass confusion about what is happening. A Russian propaganda campaign is actually a layer cake of misdirection through a series of changing stories. People become confused about what is happening and are likely to lose focus.
Dislaimer: I am not a food science guy and I have no formal training in dairy science. However, I worked in a dairy processing plant as a lab tech for three years and picked up a few things. This is my perspective from the manufacturing side.
Having worked in a dairy processing plant, I learned that there is no mystery to how cheese was invented/discovered. Just let milk sit unrefrigerated for a few days and it will clabber up. Stray bacteria, yeasts and mold spores are in the air and breath everywhere and many, if not most, are capable of feeding on the milk. In doing so, acids may be produced which will denature and unravel the proteins and bring them out of solution as a solid. Many microorganisms can ferment milk, but that is not to say that the cheese will be desirable or even edible. Before refrigeration, cheese was inevitable. Even with refrigeration cheese will happen, only a bit slower. Be one with the cheese.
As an undergraduate, lo these many years ago, I spent a few years working in the QC lab of a diary processing plant. My job was to perform certain analytical and microbial quality control procedures on the many products the plant manufactured. We produced fluid milk, cottage cheese, sour cream, whipping cream, half-and-half, single serving dairy creamers, a flavored shake product, orange juice, and flavored novelty beverages for kids. We packaged under our brand as well as for other brands.
People are very particular about their milk. Chunky milk sets off alarm bells for most of us. Many people dump their milk at the expiration date. Unless the milk has been allowed to warm up to room temperature or it has been contaminated, it should be good for another week. The expiration date is when the producer’s guarantee of freshness expires, not when it will go bad. Encountering pathogens in milk is comparatively rare these days.
The input of milk to the plant was in the form of raw milk straight from the farms by way of shiny stainless steel tanker trucks. We would receive 2-3 6000 gallon tankers per day. If we rejected a tanker, there always seemed to be another plant nearby that would take it. Rejections, which were few, were usually due to off-flavors picked up from the farm or it was high in coliforms.
Before the milk was unloaded it had to be tested. First, the receiving operator would insert an agitator into the tanker manway and stir the raw milk to mix the cream back into the milk. He would then use a stainless steel dipper and pull out a sample for the first tests. The temperature of the tank load would be taken, then the sample would be thermostatted to a specified temperature. At this point he would take a mouth full and approve it for taste and odor. This is called an organoleptic, or taste, test. He claimed to be able to detect the odor or taste of the cow (cowy), the barn (barny), grass (grassy), and certain weeds (weedy) in the cows diet. I have never been an enthusiastic milk drinker and having an aversion to tasting raw milk, I never took the opportunity to verify these flavors.
A twirl pack. Image from the interwebs.
He would then place a sample in a twirl pack, label it and send it to the lab for approval. There were several tests it had to pass before approval could be made. The % solids had to be above a particular value. To do this test, we would pipette a specified volume of raw milk onto an absorbent fiberglass pad and cover it with another. Then into the microwave it goes. The microwave had a built-in electronic balance so it would readout the % solids directly after drying. This is done to detect shipments that had been diluted with water. Milk was bought and sold by the pound or hundred weight and it was not unknown for farmers in the past to “extend” the weight of their milk production with water.
The pH of the milk was taken as a cross check to be sure that fermentation wasn’t underway. When milk ferments, it gradually becomes more acidic and will keep going until the acid inhibits further growth. In days past it was not unknown for farmers to neutralize fermenting milk with NaOH or some other base. While this could put the pH back where it should be, it would affect the % solids and the flavor. It was a trick of last resort.
The raw milk sample was also tested for beta-lactam antibiotics by two methods before approving the tanker. Cows were prone to getting mastitis from an aggressive milking schedule. Excessive dosing of dairy cattle with antibiotics to get them back into production could lead to antibiotics showing up in the milk. The state regulators watched this closely.
We used a standard disk assay method looking for inhibition in the growth of bacillus stearothermophilus spores suspended in agar growth media (it has been renamed Geobacillus). A small disk of filter paper wetted with a milk sample was placed on a petri dish of B. stearothermophilus spores in agar was warmed for 3-4 hours at 50 to 60 C. A positive result would appear as an inhibition ring around the disk indicating suppressed microbial growth. This was always compared with a disk spiked with a standard. A positive result would be recorded if the inhibition ring around the sample was larger than the ring around the standard. This test took a bit of time so it was used mainly as a cross check for the “Charm” test.
A faster test for beta-lactam antibiotics was the Charm test. This test used a radiolabeled reagent that would indicate the presence of beta-lactam antibiotics in a test sample. The sample was placed on a planchet which was heated to dryness and then put in a radiation counter for a set period of time. The turnaround time was ~15-20 minutes. This allowed for faster approval. From a Google search, it doesn’t appear that this version of a Charm test is now in service. It appears that a test strip can be used instead.
In the dairy business the fat content of milk is very important. It is a milk component that can be isolated and used to produce high margin products like ice cream, novelties, whipping cream, coffee cream and half-and-half. Every day there is a milk fat budget that you must work within. Regular drinking milk, sometimes called fluid milk, is graded into fat content categories. There is 0.5 %, 1 %, 2 %, and what we referred to as “homo”, referring to homogenized, regular 4 %. All of the fluid milk is homogenized.
Once the raw milk is approved, it must be altered in a few ways to make it shelf stable and presentable. The more equipment milk passes through, the more chance there is to give it an off-flavor. It is homogenized to produce a uniform, stable dispersion. This prevents the milk from separating on storage to form a cream layer on top. Many people like having the cream separate from the milk, however.
Early in the processing is the centrifugation step. Our plant had a centrifuge (“separator”) that would separate any solids present in the raw milk The centrifuge consisted of a stack of spinning conical plates that separated the cream as well as any solids present. The solids included cow hair, cellular matter, and dirt- stuff that you don’t want to dwell on. The fat content of milk skimmed in this way could be precisely controlled and operated on a continuous basis.
From the manufacturing point of view, processing and packaging an inhomogeneous mixture is a quality control problem. First, a continuous flow process works better if the composition of the material is uniform. Making sure that every customer gets their fair share of quality, creamy milk is important for making happy customers. Second, if the fluid milk composition is variable over time, it is hard to guarantee that you will recover enough of the valuable cream you want to divert for other products yet produce consistent fluid milk. In milk processing, consistency is everything.
Homogenization of milk can be done in a couple of ways, but they all share the process of shearing a 2-phase liquid. A jet of milk can be aimed at a stationary plate. The shear in the fluid at impact can break up the fat globules into a smaller size to give a stable suspension. The more popular method is to apply shear by forcing the milk through very small openings at high pressure. Shearing a liquid is a stretching action on a parcel of the fat leading to dispersal of the fat globules into smaller droplets and better dispersion.
At some point milk producers discovered that there was a market for low fat milk. Producers were happy to expand into this market because it would bring diet-conscious customers back into consuming fluid milk. Milk was commoditized long ago so there are many competitors out there grasping for your dairy dollars. For producers, low fat milk is an opportunity to direct excess dairy fat into more profitable products while keeping the volume in fluid milk sales up. A steady flow of commodity product is always a good thing for a business.
In production, milk fat content is something that has to be carefully managed. X pounds of dairy fat come into the plant every day and X (minus losses) pounds go out as product. You want to produce as much high margin, high-fat product as possible but you must also stay competitive in the fluid milk business. Commodity fluid milk keeps stable cash flow and your valuable shelf space in the supermarkets.
When the tankers come in at 4:00 am you want to get a fat content for the accountants and the plant managers. We paid for raw milk on the basis of fat content and weight. The standard fat test method we used was a volumetric test called the Gerber method. We would combine a standard volume of milk with butanol and fairly concentrated sulfuric acid in a Babcock bottle and heat it. We would then spin it in a centrifuge to separate the fat layer from the acidic layer. The fat would rise into the calibrated neck of the flask where we would directly read off the value using a caliper. The butanol helped to clarify the fat layer.
On occasion the plant’s fat budget would get misaligned and milk fat (cream) would have to be tanked in from elsewhere.
The plant produced about 1 million small dairy creamer cups per month that are for a single portion of coffee. The creamer fat % was determined for the batch, not individually. Samples were, however, individually tested for bacteria and taste and taken every 15 minutes.
We produced sour cream using active cultures for fermentation. We packaged sour cream as well as several flavors of potato chip dip. Chip dip is just sour cream flavored with solid spices. It is interesting to note that active bacterial cultures can become infected and die from a virus called a bacteriophage or just “phage“. Having a phage rampaging through your fermentation and packaging operation is a serious problem. You must shut everything down, maybe dispose of your raw materials and the latest product lots, and then hit everything with bleach and scrubbing and then restart with close attention.
We produced whipping cream and half-and-half. The whipping cream was produced as a heavy whip with about 36 % fat. Half-and-half was around 12 % fat. These two products were sold as sterile products meaning that they were, unlike fluid milk, completely free of bacteria. More on that in a bit.
Pasteurization of milk was an important improvement that dramatically improved the shelf-life of dairy products as well as reducing the incidence of milk-borne infection. In times past, milk-born illness was a serious problem. Today it is only greatly attenuated, not eliminated. Milk is an excellent growth medium for microorganisms like bacteria, yeasts and molds. There is water, fats, proteins and sugars. The udders of a cow are low to the ground and back where the manure comes from. Contamination of the udders is a given. Good sanitation from the udders to the consumer must be in place at all times.
Back then, the word was that it took about 2000 bacteria per milliliter to cause an off-flavor. However I cannot verify this.
The trick to milk processing is to avoid contaminating it during manufacture and packaging. Bacteria, yeasts and mold spores are in the air and everywhere else. We assayed for general microbial contamination and specifically for E. coli. The general assay was for the general hygiene of the plant and raw milk. The E. coli testing was used to gauge the microbial contamination from the operators. Humans harbor coliforms naturally in the gut. We live with them in harmony. They crowd out pathogenic bacteria for us and in turn we feed them. However, if our personal hygiene habits are poor, coliforms will show up in the product. The hands are the usual source of contamination. It must be understood that not all coliforms are pathogenic. Occasionally a pathogenic strain shows up and spreads around, making people very sick or worse. Unfortunately, these bad strains are only discovered after people start getting sick. So, as a kind of canary in the coal mine, coliform tests are used to measure the processing hygiene of the process.
The state health department was always very interested in coliform contamination. They would collect dairy products from the supermarket and test them for coliforms. A bad result would immediately cause the heat to be turned up on the plant managers. It was infrequent but taken very seriously. It usually pertained to cottage cheese. Cutting and collecting the curds was a manual operation, though the operators always wore gloves. The health department could embargo a plant’s output from the market for repeat offenses.
In common use is the HTST, High Temperature Short Time, method of pasteurization. HTST involves a short contact time of fluid milk with a moderately “high” temperature surface. This was done in a “press” which was a horizontal stack of alternating plates through which a heat transfer liquid and fluid milk would pass. The plates were compressed with a screw device holding them together under pressure- a press.
Be sure to understand that pasteurization does not equal sterilization. There is pasteurization and there is ultra-pasteurization. The first is an attenuation of the microbial load. The second refers to sterilization from ultra-high temperature, UHT, processing. In the case of American fluid milk, the kind that requires refrigeration, it is attenuated only. It is not sterile. This milk is usually good for 1 week past the expiration date if it has been constantly refrigerated. If it has been warmed to room temperature, then it is good for about 1 day, give or take. When a bacteria culture grows, the population rises slowly for a short time and then ramps into what is called the log phase (logarithmic growth). The population of bacteria grows via binary fission which is exponential growth. This situation leads to spoilage.
Milk and other dairy products that do not require refrigeration have been ultra-pasteurized by UHT. This is a bit delicate because too much contact time could lead to caramelization of the milk. These products should be sterile and an unopened container should have a long shelf-life at room temperature. Once the container is open and exposed to anything external it is subject to microbial growth.
The automated packaging equipment would spray in a small shot of concentrated hydrogen peroxide (~35 %) into the empty packages in an effort to cut down on microbial contamination just prior to the filling stage. Hydrogen peroxide is unstable in milk and decomposes quickly. Unfortunately, some bacteria have catalase which rapidly decomposes hydrogen peroxide into oxygen and water, thereby making them resistant to the sanitizing effect of the peroxide. Some bacteria, like Pseudomonas aeruginosa, are resistant to hydrogen peroxide.
On one occasion we encountered agar plates from a fluid milk sample that became green after the normal incubation. We had never seen this before. I opened a dish and took a whiff. It was fruity smelling. Since I had taken microbiology as an elective as an undergrad (chem major) I was aware that Pseudomonas aeruginosa was famous for its fruity smell, but cultures of it were blue. I performed a catalase test by pouring some hydrogen peroxide on the plate and the peroxide immediately began to fizz- positive result. This was consistent with P. aeruginosa. But why was the plate green? Well, when you have a bacterium that produces blue colonies in a yellow agar medium, you get green. Presto, we identified it. We dumped the lot and cleaned the equipment and never saw it again.
Our ultra-pasteurized products were sampled by taking packaged milk off the packaging line every 20 minutes and putting it into a 90 F hotbox for 48 hours. After the time was up we opened each container and put a sterilized loop into it and inoculated an agar plate. Then the containers were each tasted by the lab tech (me) for any off flavors. Most samples passed both the microbial and the taste testing. Usually there were several in the 4 or 5 milk crates that were bad. I’ve never been a big fan of milk when even it is cold, so this warm milk at the end of its shelf life was no picnic. We would open a carton, take a swig and hold it long enough to pick up the taste, then spit it into the sink, holding back the gag reflex all the while. We tended to do this rapidly to get it over with, but in doing so we would occasionally get a mouthful of sour milk with chunks or just whey. Both would be carbonated and tangy from fermentation and sometimes show stormy fermentation. It was gross and disgusting. Heavy whip that was clean would sometimes be surreptitiously churned into butter by a certain lab tech who was eventually caught and fired. He was handing it out to folks in his church. Management said it was a case of a dairy product of unknown quality leaving the plant. Yeah, Ok.
UHT fluid milk stored at room temperature is popular in Europe and a few other countries but not so much in the US. I guess we’re just squeamish about milk here. I know I am.
Our plant also produced cottage cheese. No big mystery here. We filled a rectangular vat with warmed skim milk and added a mixture of weak acids to it. I recall that the curdling acids was a mix of phosphoric and lactic acids. This method was known as “direct set.” After a short time the milk curdled with the white curd floating as a solid mass in the yellowish whey. The operators would use a multibladed knife the cut the curds into cube shaped chunks. Then the whey was discarded into the sanitary sewer and the curds were washed and loaded into a machine for packaging. Most cottage cheese was blended with a salted cream to give it a creamy texture. Some of the curds were packaged as “dry curds”.
For a long time the plant would send the whey from the cottage cheese process down the sanitary sewer. Then one day we were given a very large sewer bill. It had jumped from $2,000 to about $26,000 per month. You could hear a clattering noise from all of the bricks the accountants were shi**ing. The giant invoice was for all of the biological oxygen demand (BOD) that our whey was actually consuming at the sewage treatment plant. The folks at the treatment plant had been noticing that the BOD of the sewage going into the plant had been swinging around but couldn’t figure it out. Then one day they noticed that the problem popped up when they saw cheese curds floating in with the waste. They connected the curds and presented us with a hefty bill for the plant capacity we were consuming by dumping whey down the drain. Soon thereafter we sold the whey to hog farmers. Whey has a few percent of protein content. The farmers were happy but we never heard what the pigs thought.
Finally, we had a juice packaging operation. We produced orange juice and a small portioned flavored beverage that went by some childish name. We bought orange juice concentrate in 55 gallon drums and would just dump it into a mixing vat and dilute it to spec. Easy peasy. It would then go to packaging in the isolated juice room. Same with the other beverage. I think we had more contamination issues with the juice than anything else. The juice was especially prone to going off from yeasts and molds. There was usually gas generated that would bulge the containers. This became a serious shelf-life issue when it happened. Instead of bleach they cleaned the juice room with quaternary ammonium based cleaning agents (“quats”). I think we mistakenly thought that the contamination came from us. It could have been spores riding along with the concentrate. We never tested for that.
We had a large, chilled warehouse held at 38 F for storing product. We also had a cold box at -40 F for warehousing ice cream from another plant. The plant was also a distribution center. The chiller plant used ammonia. When it needed maintenance, it was critical to get a reefer guy who would work on ammonia systems. Not everyone will do this.
I learned a bunch and grew from doing this work. I don’t think I’ll go back though.
While cockeyed optimists are working toward a new age of electric vehicles in the glare of an admiring public, I find myself standing off to the side mired in skepticism. What are the long-term consequences of large-scale electrification of transportation?
The industrial revolution as we in the west see it began as early as 1760 and continues through today. Outwardly it bears some resemblance to an expanding foam. A foam consists of a large number of conjoined bubbles, each representing some economic activity in the form of a product or service. A business or product hits the market and commonly grows along a sigmoidal curve. Over time across the world the mass of growing bubbles expand collectively as the population grows and technology advances. Bubbles initiate, grow and sometimes collapse or merge as consolidation and new generations of technology come along and obsolescence takes its toll.
The generation of great wealth often builds from the initiation of a bubble. The invention of the steam engine, the Bessemer process for the production of steel, the introduction of kerosene replacing whale oil, the Haber process for the production of ammonia and explosives, and thousands of other fundamental innovations to the industrial economy played part in the growing the present mass of economic bubbles worldwide.
After years of simmering on the back burner, electric automobile demand has finally taken off with help from Tesla’s electric cars. Today, electric vehicles are part of a bubble that is still in the early days of growth. The early speculators in the field stand the best chance of winning big market share. A major contribution to this development is the recent availability of cheap, energy dense lithium-ion batteries.
Of all of the metals in the periodic table, lithium is the lightest and has the greatest standard Li+/Li reduction potential at -3.045 volts. The large electrode potential and the high specific energy capacity of Lithium (3.86 Ah/gram) makes lithium an ideal anode material. Recall from basic high school electricity that DC power = volts x amps. Higher voltage and/or higher amperage gives higher power (energy per second). Of all the metals, lithium has the highest reduction potential (volts).
Rechargeable lithium batteries have high mass and volume energy density which is a distinct advantage for powering portable devices including vehicles. Progress in the development of lithium-ion batteries was worth a Nobel Prize in 2019 for John B. Goodenough, M. Stanley Whittingham and Akira Yoshino.
All of this happy talk of a lithium-powered rechargeable future should be cause for celebration, right? New deposits of lithium are being discovered and exploited worldwide. But cobalt? Not so much. Alternatives to LiCoO2 batteries are being explored enthusiastically with some emphasis on alternatives to cobalt. But, the clock is ticking. The more infrastructure and sales being built around cobalt-containing batteries, the harder it will become for alternatives to come into use.
One of the consequences of increasing demand for lithium in the energy marketplace is the effect on the price and availability of industrial lithium chemicals. In particular, organolithium products. The chemical industry is already seeing sharp price increases for these materials. For those in the organic chemicals domain like pharmaceuticals and organic specialty chemicals, common alkyllithium products like methyllithium and butyllithium are driven by lithium prices and are already seeing steep price increases.
Is it just background inflation or is burgeoning lithium demand driving it? Both I’d say. Potentially worse is the effect on manufacturers of organolithium products. Will they stay in the organolithium business, at least in the US, or switch to energy-related products? It is my guess that there will always be suppliers for organolithium demand in chemical processing.
A concern with increasing lithium demand has to do with recycling of lithium and perhaps cobalt. Hopefully there are people working on this with an eye to scale up soon. A rechargeable battery contains a dog’s lunch of chemical substances, not all of which may be economically recoverable to specification for reuse. In general, chemical processes can be devised to recover and purify components. But, the costs of achieving the desired specification may price it out of the market. With lithium recovery, in general the lithium in a recovery process must be taken to the point where it is an actual raw material for battery use and meets the specifications. Mines often produce lithium carbonate or lithium hydroxide as their output. Li2CO3 is convenient because it precipitates from aqueous mixtures. It must also be price competitive with “virgin” lithium raw materials as well.
Lithium ranks 33rd in terrestrial abundance and less than that in cosmic abundance. Unlike some other elements like iron, lithium nuclei formed are rapidly destroyed in stars throughout their life cycle. Lithium nuclei are just too delicate to survive stellar interiors. The big bang is thought to have produced a small amount of primordial lithium-7. Most lithium seems to form during spallation reactions when galactic cosmic rays collide with interstellar carbon, nitrogen and oxygen (CNO) nuclei and are split apart from high energy collisions yielding lithium, beryllium and boron- LiBeB. All three elements of LiBeB are cosmically scarce as shown on the chart below.
Lithium is found chiefly in two forms geologically. One is in granite pegmatite formations such as the pyroxene mineral spodumene, or lithium aluminum inosilicate, LiAl(SiO3)2. This lithium mineral is obtained through hard rock mining in a few locations globally, chiefly Australia.
Source: “A Preliminary Deposit Model for Lithium Brines,” Dwight Bradley, LeeAnn Munk, Hillary Jochens, Scott Hynek, and Keith Labay, US Geological Survey, Open-File Report 2013–1006, https://pubs.usgs.gov/of/2013/1006/OF13-1006.pdf
Chemical Definition: Salt; an ionic compound; A salt consists of the positive ion (cation) of a base and the negative ion (anion) of an acid. The word “salt” is a large category of substances, but for maximum confusion it also refers to a specific compound, NaCl or common table salt. In this post the word refers to the category of ionic compounds.
The other source category is lithium-enriched brines. The US Geological Survey has proposed a geological model for brine or salt deposition. According to Bradley, et al.,
“All producing lithium brine deposits share a number of first-order characteristics: (1) arid climate; (2) closed basin containing a laya or salar; (3) tectonically driven subsidence; (4) associated igneous or geothermal activity; (5) suitable lithium source-rocks; 6) one or more adequate aquifers; and (7) sufficient time to concentrate a brine.”
Lithium and other soluble metal species are extracted from underground source rock by hot, high pressure hydrothermal fluids and eventually end up in subsurface, in underwater brine pools or on the surface as a salt lake or a salt flat or salar. These deposits commonly accumulate in isolated locations that have prevented drainage. An excellent summary of salt deposits can be found here.
Critical to any kind of mineral mining is the definition of an economic deposit. The size of an economic deposit varies with the market value of the mineral, meaning that as the value per ton of ore increases, the extent of the economic deposit may increase to include less concentrated ore. If you want to invest in a mine, it is good to understand this. A good opportunity may vanish if the market price of the mineral or metal drops below the profit objectives. Hopefully this happens before investment dollars are spent digging dirt.
Lithium mining seems to be a reasonably safe investment given the anticipated demand growth unless страшный товарищ путины invasion of Ukraine lets the nuclear genie out of the bottle.
Just for fun, there is an old joke about the definition of a mine-
Mine; noun, a hole in the ground with a liar standing at the top.
Lamentations on Chemistry 