Monthly Archives: February 2008

That Pesky Brazil Nut Effect

2 Replies

The Brazil Nut Effect is a type of equilibration process that granular systems with a distribution of particle sizes will undergo. It occurs with agitation and proceeds in such a manner as to result in a final state with the center of mass as low as possible. The equilibrated state results in the larger particles migrating towards the top and the smaller particles filling the void spaces down low. According to the above Wikipedia site, certain container shapes can suppress or enhance this effect.

In the merchant chemical business, suppliers strive to provide customers with the maximum quality that is feasible.  Some applications require high chemical purity and others require less purity. The trick is to pay for the purity that you need.  Excess purity is an unnecessary expense.

In many applications a chemical substance must be both chemically pure and of a certain specific physical form.  For applications where the solid must be blended to form a suspension, a slurry, or it must dissolve rapidly, a small particle size is often desirable. Particle size control and analysis is an art that many synthetic chemists can go through their entire careers and never encounter.

In the process of filtration, solids often compact along surfaces to afford flakes and angular chunks that may retain their shape until they reach the package. Lumps can arise from incomplete washing and drying and may be indicative of chemical inhomogeneity in the bulk material. 

Chemical products that are used in compounding for very exacting applications- catalysts, coatings, polymer compounding- may have specifications that require the absence of lumps in the bulk solid. Free flowing homogeneous powders can be prepared by milling or sieving or even spray drying. Compounds that are air, moisture, or light sensitive may not respond well to excessive handling. Before you accept business involving powdered products with bulk solid specs, you need to demonstrate that it is art that you can actually perform.

This is where a smart buyer is worth their weight in gold. Instead of having their own company take the burden of particle sizing, they make the vendor do it. And if the vendor fails, find another.

Where the Brazil Nut Effect seems to enter my life is when the product finally arrives at the customers facility.  If your nice powder had even a single hidden clump in it, you can bet that on arrival it has migrated to the surface to greet the frowning customer. I have received digital photographs of this from customers who wished to drive home the point. So, you just buck up and apologize as sweetly as you can manage and give them your FedEx number so they can send it back.

Send your Gluteal Scan to the FBI

Leave a reply

It is hard to believe with all of the “good” news lately that the US gvernment is on our side. The Bush II Y2009 budget proposal comes in at a stunning $3.1 Trillion against an estimated $2.5 Trillion in receipts.

The FBI wants to collect biometric data on US citizens. It wasn’t clear to me as to whether they want to collect this data as law abiding citizens go about their business at airports with iris scans and electronic fingerprints, or if they will limit the effort to people taken into custody.  In any case, the notion of our government collecting ever more data on its citizens should bring chills to everyone.  It is all about control. Once taken, never returned.

I, for one, would be only too happy to fax a photocopy of my biometric gluteal cleft to the FBI to post wherever it suits them. It shines like a mackerel in the moonlight. In fact, there is a protest movement I could get on board with- The Million Man Moon on Washington.

The Customs and Border Patrol agency has proposed the new “10 + 2” rule which should be a real delite to deal with. We’re already scrambling to figure out what the hell this means for the purchasing people.  Lots of detailed info will have to be timed properly to keep things moving through customs.  It’s going to be a big mess and the only benefit will be that the government will collect more duties.

Chinese Cyberwar and US Interests

6 Replies

An intelligence report posted by International Relations and Security Network (ISN) at the Center for Security Studies at ETH in Zurich reveals what appears to be a widening and systematic program of cyber attacks on US government data infrastructure by elements within the military organ of China.

Rachel Kesselman at ISN Security Watch writes-

According to a 2006 US Defense Department report, the Chinese People’s Liberation Army (PLA) began developing information warfare reserves and militia units in 2005, often incorporating them into broader exercises and training. The establishment of this elite Chinese unit is evident by a likely increase in sophisticated attacks on high-risk targets.

Reports in Chinese newspapers also suggest that the Chinese are actively attempting to establish a cybermilitia. A Time Magazine article entitled “Enemies at The Firewall” purports that the military has put forth a concerted effort to carry out nationwide recruiting campaigns in hopes of discovering the country’s most brilliant hackers. 

Like so many Americans, I live in a bubble. The extent and brazenness of the activity reported by ISN and other sources only serves to stimulate the paranoid cortex of my brain.

What seems likely is that most nations are engaged in systematic probing of the data resources of the upper tier states. Chinese enthusiasm for this activity may or may not be exceptional among the nuclear states. Certainly, computer spycraft is nothing new and that China practices it shouldn’t be a surprise.

Henry Kissinger once remarked that nation states do not have friends. They only act in parallel with states having similar interests. In this vein, we should not be lulled into thinking that China, or any other state for that matter, is our friend. China is certainly not our friend. The US is a fountain of wealth that they aim to tap through government backed market activity.

Economic idealogues in the US prattle on tirelessly about the virtues of the free market and the merits of regulatory deconstruction. But on the global scale, markets are unavoidably tied to regulatory constructs as a result of notions about security and dominance.

Just try to get a shipment of anything to China or to South Africa or into the USA. There is no free market. Every single aspect of a transaction is highly regulated or controlled by some apparatus that is highly controlled. Tariff codes, tariffs, shipping reglations, wire transfers, and customs clearance- the reality of a free market barely extends past the canopy of a fruitstand in a farmers market.

I believe that the US should cast off this free market puritanism and act in a manner so as to protect its economic interests. Yes, we’d like to keep as free a market as possible. But American culture, not government, has to be the locus of change. American culture should de-emphasize its fascination with pure wealth and look askance at the sterile detachment many influential businessmen have with regard to their profit motive. We want to be profitable. But we do not want to hand over the keys to our technological toolshed for a quick buck. If we cannot afford to manufacture here, there should be an expectation that we try to innovate around the economic barriers rather than just resort to abandonment.

We should be wary about using the language of friendship with China. This nation has its own sense of where it is headed and has become quite refractory to admonitions and paternalistic brow beatings by the US and others.  It has its own momentum and will do what is in its best interest. Americans should do what is in their best interest as well. That is, avoid trading the farm to foreign interests who have much more discipline with their attention span. 

America’s Achilles heel seems to be the inability to be patient and plan for results over the long term. We live in a NOW culture. Advances in computer technology has only engorged our expectation that we can and should have everything now. The mortgage and credit crises are only the latest examples of this.

American culture has gotten fat and lazy. Our rotund wastelines are only the exterior. Within our culture is a kind of bacchanalian sloth that has drifted like a fog into our collective yard party. Everyone is too busy eating and drinking to notice that the greed-heads have set the house on fire.

Beatles in Space

1 Reply

NASA has announced that it will broadcast a 4 minute digital data stream toward the direction of Polaris, the North Star. The broadcast will originate from the Deep Space Network and will feature the Beatles song “Across the Universe“. 

Again, NASA has neglected to solicit my advice. I would have suggested “I am the Walrus“.

Imagine an you’re alien sitting in a remote antenna site with headphones over your ear stalks when all of a sudden Day Tripper appears over the background noise. [I like the dancers- it’s just so 60’s]

Of course, when the signal is received on planet Pffthklct-3 many centuries from now, someone some sentient mollusk will have to clean up the signal and reduce it to audio to get the full effect of music. Doppler effect arising from relative motions between earth and “them” would affect the tempo, perhaps in comical ways.  It would be tragic if hopeful listeners in the depths of space mistook it as a kind of Encyclopedia Galactica and henceforth tried to decrypt it while looking for some kind of blueprint of advanced technology a la Carl Sagan’s fictional piece “Contact”.

Though an audience is a long shot, it seems a fitting tribute to the Beatles and to NASA.

Analytical Life Without NMR

Leave a reply

We synthetikkers live in the gilded age of NMR. This analytical method is so fast and so rich in quantitative and structural details that we may forget what it’s like to produce materials that aren’t amenable to NMR rigged for liquid samples and H, C, F, B, Si, and P.

I’ve been busy making metal oxides and various complexes for sale that lend themselves to a very short list of analytical methods. When you make compounds for sale you have a responsibility to provide an unambiguous assay of purity for the lot.  Compounds that are poorly soluble, paramagnetic, or lack NMR active nuclei can be problematic for NMR assay in a production setting. Yeah yeah, I know- get a solid state NMR. Well, we don’t have one and it ain’t gonna happen in my lifetime. Meanwhile, I have 200 g of new product that needs to get certed and into inventory.

Lately I have been taking cues from catalog company web-sites and exploring other methodologies. Complexometric titrations for metals assay, AA, gravimetric AgX for halides, Karl Fischer for water, Loss On Drying (LOD) for volatiles (water, solvents), combustion analysis (C, H, & N), Glow Discharge MS (the Big Hammer) for refractory metal oxides, XRD for anything that could be in the xtal database, melting points, TGA, and I’m turning back to FTIR. 

I haven’t been using FTIR in a quantitative way, just looking for a “Conforms to Structure” result. But nonetheless, in the preparation of new compounds for the product list it is a life saver. I can convince myself that the desired ligands are there and use other methods to try to quantitate their wt %.

I always feel better if we can come up with 3 methods that corroborate the composition. You don’t always have to come up with methods that are on the specification either. It is reasonable to report results on a Certificate of Analysis that are “Report Only” and show general conformance rather than some percentage quantity.  Examples might be appearance, color, or even an NMR spectrum.

I have only recently begun to use XRD and am a mere novice in its intracies. I have sent solid solutions where components that I knew to be there were not detectable. I have also sent samples that came back with % compositions of several xtal phases. For characterization of production lots, it has utility in the detection of certain components. Amorphous phases and random, solid solutions are a blind spot for the method. On the other hand, there is ca one half million compounds in the database so it can detect xtal phases down to ~ 1%.

I have learned an expensive lesson in regard to ICP MS. The method is quite blind or unreliable with certain elements. Sulfur and halides in particular. A sample can be loaded with sulfur (often as sulfate) and the assay will come back with a wildly low value. An ICPMS assay of rare earth metal oxides can support a claim for 99.99 % total rare earth oxides. A GDMS of the same sample may show that it is 99.8x % in metals and even lower if you include halides, sulfur, and phosphorus. 

To be fair to purveyors of ICP MS, it is quite sensitive but standards at the lower limit of detection may not be available. Sub ppm numbers without an explanation of conditions and error are to be taken with skepticism.  Everything looks like a dogs lunch once you get down to the sub ppm level.