Microprecipitation

An electron microscopy study by Mullen et al. (1989) showed that Cd2+, Cu2+ and La3+ accumulated on the cell surface of Bacillus cereus, B. subtilis, E. coli and Pseudomonas aeruginosa as needle-like, crystalline precipitates, while Ag+ precipitated as discrete colloidal aggregates at the cell surface and occasionally in the cytoplasm. The needle-like and hexagonal precipitates were also found for the biosorption of Ni2+ on the cell surface of P. fluorescens 4F39 at pH 9 and it was suggested as a microprecipitation process that followed on ion exchange (Lopez et al. 2000). 

Aggregates are microprecipitates of tens to thousands of polymer molecules which can be invisible to the naked eye or appear as a faint cloudiness in the solution. They form when a poor solvent such as methanol is added to a molecularly dispersed solution of the polymer in a good solvent, such as toluene or THF, or vice versa. Since aggregates are the first stage of a solid precipitate, they are also useful as model materials of the solid bulk state polymers and are amenable to study by many solution techniques such as solution-state UV and CD spectroscopy. Chiral molecules... 

TEM examination of GaN crystals by Liliental-Weber et al [27] determined that one of the polar surfaces of high pressure solution-grown GaN crystals (especially for the smaller ones) is often atomically flat (2-3 monolayer step heights present) and that the crystal under this surface is practically free of extended defects. On the opposite surface, a number of extended defects like stacking faults, dislocation loops and Ga microprecipitates were observed. The relative thickness of the defect-containing part usually consists of 10% of the entire thickness of the platelet. 

A microchemist is a man who does microanalysis or microsynthesis. He studies microreactions in microtest-tubes. He collects microprecipitates on microfilters and weighs them on a microbalance, or makes microtitrations... 

Ceftazidime formed microprecipitates when it was mixed with vancomycin (209). 

Ciprofloxacin 0.3% ophthalmic drops can cause microprecipitates of pure ciprofloxacin in the corneal epithelium (17). In four corneal transplantation patients treated preoperatively with ciprofloxacin 0.3% ophthalmic drops, there were microprecipitates associated with damaged corneal epithelium in two patients another developed a macroprecipitate in a corneal ulcer (18). The crystalline precipitates were pure ciprofloxacin. 

Eiferman RA, Snyder JP, Nordquist RE. Ciprofloxacin microprecipitates and macroprecipitates in the human corneal epithelium. J Cataract Refract Surg 2001 27(10) 1701-2. 

Colour tests are also given by Fulton [106]. Precipitation tests are given by references [107-14 inc.], microprecipitation tests by references [5, 114-20 inc.], and other methods of detection and identification of codeine by references [121-42 inc.]. 

Colour tests are also given by Fulton [48]. Precipitation tests [49-53] and microprecipitation tests [54] have also been devised. 

Sequence modifications which increase the isoelectric point of insulin from 5.4 toward neutrality led to analogs which form microprecipitates and have extended duration of action (29, 75). Following this concept, addition of... 

Microprecipitation and High shear (NANOEDGE ) Nanopure XP technology... 

For this reason, float-zoned silicon intended for the fabrication of semiconductor power devices is often specified -to contain low carbon concentration, e.g., less than 1 ppma. Carbon has been reported to play a role in the heterogeneous nucleation of oxide precipi-tates (37-40). In principle, carbon nucleation of oxide microprecipitates could be used to advan-tage in designing IC processes. In practice, however, the nonuniformity of the carbon distribution renders this an impractical approach. Thus in order to avoid uncontrolled variations in the oxide precipitation, low-carbon silicon is often specified for processes which use intrinsic gettering. 

Weaver, R.M., Hochella, M.R. and Ilton, E.S., Dynamic processes occurring at the Cr , -manganite (y-MnOOH) interface Simultaneous adsorption, microprecipitation, oxidafion/reduction and dissolution, Geochim. Cosmochim. Acta, 66,4119, 2002. 

L/TC < 0.6), and labile microprecipitation occurs when A d,/T exceeds 1.6. In 10 g/dl mixtures, the microprecipitates initially range in size from 500 to 20000 A and later coalesce to form a buoyant macroscopic precipitate phase. In 3... 

Separation and concentration from the bulk matrix are accomplished by combinations of precipitation, ion exchange, solvent extraction, electrodeposition, or microprecipitation techniques appropriate to produce a sample for the detection instrument [26,31-35]. 

J. E. Kipp, J. C. T. Wong, M. J. Doty and C. L. Rebbeck, Microprecipitation method for preparing submicron suspensions. United States Patent 6,607,784, Baxter International Inc. (Deerfield, IL) (2003). 

---