UNAIDS

Microchemical or ultramicrochemical techniques are used extensively ia chemical studies of actinide elements (16). If extremely small volumes are used, microgram or lesser quantities of material can give relatively high concentrations in solution. Balances of sufficient sensitivity have been developed for quantitative measurements with these minute quantities of material. Since the amounts of material involved are too small to be seen with the unaided eye, the actual chemical work is usually done on the mechanical stage of a microscope, where all of the essential apparatus is in view. Compounds prepared on such a small scale are often identified by x-ray crystallographic methods. 

Vibrofluidizatlon It is possible to fluidize a bed mechanically by imposing vibration to throw the particles upward cychcaUy. This enables the bed to operate with either no gas upward velocity or reduced gas flow. Entrainment can also be greatly reduced compared to unaided fluidization. The technique is used commercially in drying and other applications [Mujumdar and Erdesz, Drying Tech., 6, 255-274 (1988)], and chemical reaction applications are possible. See Sec. 12 for more on diying applications of vibrofluidization. 

Inspection. After the final adhesive cure cycle, the bonded assembly is removed from the tool and inspected. The first and most cursory inspection is a simple visual check. Major problems such as crushed core and significantly mis-located details can be seen with the unaided eye. A lack of continuous adhesive squeeze-out ( flash or spew ) around the periphery of details can be indicative of insufficient adhesive and subsequent voids. 

Silt and clay are fine-grained soils in which individual particle size cannot be readily distinguished with the unaided eye. Some classification systems distinguish these particles by size, other systems use plasticity to classify these particles. 

The standard unit normally used for measuring dust particles is the micron (pm one-thousandth of a millimeter). The smallest particle visible to the unaided eye is between 50 and 100 pm and the most dangerous sizes are between 0.2 and 5 pm. Particles larger than this are usually unable to penetrate the lung defenses and smaller ones settle out too slowly. Some dusts can be both toxic and fibrous (e.g. asbestos) and are therefore harmful even outside these parameters. It may therefore be assumed that dusts which are visible (i.e. between 50 and 100 pm), are quite safe. However, this is not the case, as dust clouds never consist solely of particles of one size. Analysis would show percentages of all sizes, and it is for this reason that special care is needed in measuring dust clouds and concentrations. 

The 2nd law, which can be stated in a number of different ways, expresses the fact that heat can only be transformed into work when it flows from a higher to a lower temperature. Clausius, stated the 2nd law as follows It is impossible for a self-acting machine, unaided by an external agency, to convey heat from a lower to a higher temperature . 

The flow patterns of agitated liquid have been studied extensively (Al, B11, F6, K5, M6, N2, R12, V5), usually by photographic methods. Apparently no work has been reported on bubble-flow patterns and relative velocities in agitated gas-liquid dispersions. Some simple pictures have been presented that only show the same details that may be seen with the unaided eye (Bll, F6, Y4). 

Some mixtures have component particles that are so large we can see them with an optical microscope or even the unaided eye (Fig. G.l). Such a patchwork... 

In a light microscope, the particle must be magnified to a size at least as large as the resolving power of the unaided human eye. The resolving power of microscope equals 1 /d, with... 

Micro-organisms (Figure 1), bacteria, moulds and yeasts, collectively known as fungi, are minute living entities, too small to be seen with the unaided eye. 

UNAIDS/WHO (2007). AIDS epidemic update December 2007. UNAIDS/ 07.27E. ISBN 92 9 173621 8. 

Then he turned away and vaulted onto his horse unaided, as he always did, though he was small and ill-made, and took the road to Stony Stratford. My only comfort was that as I mounted, unarmed and set about with many well-armed men, I looked at the sky, the clouds, and toward the west. I hope it will not rain, I said to my captors. 

Unaided human vision fails to see objects less than about 100 p, (0.004 or 1/254 inch) in diameter or to perceive as separate objects... 

United Nations program on HIV/AIDS (UNAIDS), AIDS epidemic update 2008, December, 2008, available from www.UNAIDS.org. 

There are more than 40 million people living with HIV worldwide (http // www.unaids.org/en/HIV data/), the etiologic cause of the acquired immune... 

Figure 24, presented originally by Belton (1995), illustrates the enormous range in distance scales that can be probed using various magnetic resonance spectroscopy and imaging techniques. Approximate distance ranges for molecular, microscopic, and macroscopic regions are provided for perspective on the left side of Figure 24. The criterion used for the demarcation between macroscopic and microscopic regions was based on the size of objects that are no longer visible with the naked or unaided eye, i.e., less than 40 xm (Hills, 1998).

The interpretation of reactions catalysed by metal halides was complicated and confused further by the formation of 7t-complexes between these catalysts and olefins, and the unfortunate fact that many of these complexes formed from aromatic olefins have a colour which to the unaided eye is indistinguishable from that of the triphenylmethyl and related cations. There is no evidence that these complexes are catalytic, and quite a lot that they are not. 

---