The effect of anti-foam agents on the ultrafiltration of a protease solution

Polydimethylsiloxane and polypropylene glycol-based anti-foam agents adversely influence the ultrafiltration rate of a protease solution with polysulfon membranes. Four propietary agents have been compared, of which Rhodosil 426 R (ex Rhone Poulenc, France), an emulsion of polydimethylsiloxane, proved to have the least influence. With this agent, the relative filtration flux of a protease solution decreased by a factor of two for concentrations of anti-foam agent higher than 0.25 cm³/dm³. A simple, quasisteady-state model developed on the basis of data obtained from total recycle experiments with this anti-foam agent, well predicted the temporal variation of protease concentration during batch ultrafiltration experiments with and without Rhodosil 426 R.List of Symbols A _uf m² total membrane area - C _af dm³/m³ concentration of anti-foam agent - C _af,0 dm³/m³ initial concentration of anti-foam agent in the feed solution - C _e kg/m³ protease powder concentration - C _e,0 kg/m³ initial protease powder concentration in the feed solution - J m³/s ultrafiltration rate - J _w m³/m²s water flow for a clean membrane under processing conditions - R _af rejection coefficient for anti-foam agent - R _e rejection coefficient for protein - RF % relative filtration rate - t s filtration time - V m³ concentrate volume - V ₀ m³ volume to be concentrated - V _t m³ end volume     

STORAGE AND GERMINATION OF CHARA OOSPORES

Germination tests were conducted on 39 collections of Chara oospores stored under 4 different conditions for periods of approximately 4 yr. In general, storage of dried oospores at low temperatures (3 C) provided the most satisfactory means for long-term preservation of viable disseminules. Oospore germination zuas higher in light than in darkness. Effects of temperature and substrate upon germination were explored briefly.     

The molecular and metabolic program by which white adipocytes adapt to cool physiologic temperatures

Although visceral adipocytes located within the body’s central core are maintained at approximately 37°C, adipocytes within bone marrow, subcutaneous, and dermal depots are found primarily within the peripheral shell and generally exist at cooler temperatures. Responses of brown and beige/brite adipocytes to cold stress are well studied; however, comparatively little is known about mechanisms by which white adipocytes adapt to temperatures below 37°C. Here, we report that adaptation of cultured adipocytes to 31°C, the temperature at which distal marrow adipose tissues and subcutaneous adipose tissues often reside, increases anabolic and catabolic lipid metabolism, and elevates oxygen consumption. Cool adipocytes rely less on glucose and more on pyruvate, glutamine, and, especially, fatty acids as energy sources. Exposure of cultured adipocytes and gluteal white adipose tissue (WAT) to cool temperatures activates a shared program of gene expression. Cool temperatures induce stearoyl-CoA desaturase-1 (SCD1) expression and monounsaturated lipid levels in cultured adipocytes and distal bone marrow adipose tissues (BMATs), and SCD1 activity is required for acquisition of maximal oxygen consumption at 31°C.

Adipocytes in bone marrow, subcutaneous and dermal sites generally exist at temperatures below 37°C. This study identifies the molecular and metabolic program that adapts white adipocytes to these cooler environments.     

The evolution within us

The B-cell immune response is a remarkable evolutionary system found in jawed vertebrates. B-cell receptors, the membrane-bound form of antibodies, are capable of evolving high affinity to almost any foreign protein. High germline diversity and rapid evolution upon encounter with antigen explain the general adaptability of B-cell populations, but the dynamics of repertoires are less well understood. These dynamics are scientifically and clinically important. After highlighting the remarkable characteristics of naive and experienced B-cell repertoires, especially biased usage of genes encoding the B-cell receptors, we contrast methods of sequence analysis and their attempts to explain patterns of B-cell evolution. These phylogenetic approaches are currently unlinked to explicit models of B-cell competition, which analyse repertoire evolution at the level of phenotype, the affinities and specificities to particular antigenic sites. The models, in turn, suggest how chance, infection history and other factors contribute to different patterns of immunodominance and protection between people. Challenges in rational vaccine design, specifically vaccines to induce broadly neutralizing antibodies to HIV, underscore critical gaps in our understanding of B cells'' evolutionary and ecological dynamics.     

Fear of crime among Arab Americans in a culture of fear

As the minority group frequently at the centre of public fear in the post-9/11 era, Arab Americans’ own sentiment toward, and concerns with, crime, has eluded scholarly attention. This study investigated their fear of crime net of five empirically validated fear of crime theoretical models. Face-to-face interviews with a random sample of Arab and non-Arab households in Metro-Detroit, Michigan indicated that net of all controls, Arab Americans experienced significantly higher levels of fear concerning both general and bias crimes than non-Arab Americans. The greater fear among Arab Americans calls for policy and practice change, and moving from perceiving Arab Americans as a major “source” of fear, to “carriers” of fear who are in need of more attention, care, and assistance.     

The effect of spontaneous mutations on competitive ability

Understanding the impact of spontaneous mutations on fitness has many theoretical and practical applications in biology. Although mutational effects on individual morphological or life‐history characters have been measured in several classic genetic model systems, there are few estimates of the rate of decline due to mutation for complex fitness traits. Here, we estimate the effects of mutation on competitive ability, an important complex fitness trait, in a model system for ecological and evolutionary genomics, Daphnia. Competition assays were performed to compare fitness between mutation‐accumulation (MA) lines and control lines from eight different genotypes from two populations of Daphnia pulicaria after 30 and 65 generations of mutation accumulation. Our results show a fitness decline among MA lines relative to controls as expected, but highlight the influence of genomic background on this effect. In addition, in some assays, MA lines outperform controls providing insight into the frequency of beneficial mutations.     

Temporal and spatial trends in allozyme frequencies in house fly populations,Musca domestica L.

Summary Allelic and genotypic frequencies were sampled from a single age class of the common house fly, Musca domestica L., at five farms on six dates from July 6 to October 12, 1982. Allozymes at six loci were resolved with vertical polyacrylamide gel electrophoresis. No consistent departures from random mating were detected. No consistent linkage disequilibrium was observed. Allele frequencies at the farms changed in independent and unpredictable ways. Gene frequencies at the five farms were initially divergent, converged in midsummer, and then progressively diverged. The divergence occured in mid-August when fly populations were large. Variation in gene frequencies at adjacent farms accounted for a large proportion of the variance in allele frequencies among all farms. These observations are consistent with the hypothesis that allele frequencies in young adult flies reflected the habitat in which they matured as larvae.Journal Paper No. 11718 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa, Project No. 2411     

Non-aqueous Electrode Processing and Construction of Lithium-ion Coin Cells

Research into new and improved materials to be utilized in lithium-ion batteries (LIB) necessitates an experimental counterpart to any computational analysis. Testing of lithium-ion batteries in an academic setting has taken on several forms, but at the most basic level lies the coin cell construction. In traditional LIB electrode preparation, a multi-phase slurry composed of active material, binder, and conductive additive is cast out onto a substrate. An electrode disc can then be punched from the dried sheet and used in the construction of a coin cell for electrochemical evaluation. Utilization of the potential of the active material in a battery is critically dependent on the microstructure of the electrode, as an appropriate distribution of the primary components are crucial to ensuring optimal electrical conductivity, porosity, and tortuosity, such that electrochemical and transport interaction is optimized. Processing steps ranging from the combination of dry powder, wet mixing, and drying can all critically affect multi-phase interactions that influence the microstructure formation. Electrochemical probing necessitates the construction of electrodes and coin cells with the utmost care and precision. This paper aims at providing a step-by-step guide of non-aqueous electrode processing and coin cell construction for lithium-ion batteries within an academic setting and with emphasis on deciphering the influence of drying and calendaring.