Studies on syntheses and permeabilities of special polymer membranes: 30. Ultrafiltration and dialysis characteristics of cellulose nitrate-poly(vinyl pyrrolidone) polymer blend membranes

The ultrafiltration and dialysis characteristics of the semipermeable polymer blend membranes obtained from cellulose nitrate, poly(vinyl pyrrolidone), and N,N-dimethyl formamide were investigated under various conditions. The water content fraction and the ultrafiltration rate were dependent on the poly(vinyl pyrrolidone) content in the membranes, and the strengths were governed by the cellulose nitrate content in the polymer blend. If the pore radius in the membranes, calculated according to the Hagen-Poiseuilli equation for capillary model, was identical, the water content in each membrane was not identical. It was found that urea molecules broke very weak hydrogen bonds of the bound water in the membrane, but sodium chloride did not, also, the diffusion of urea through the membrane was more rapid than that of sodium chloride. The ratio of the membrane diffusion coefficient to the ultrafiltration rate was explained qualitatively by the capillary model, however, when the bound water in the water content fraction was considered, this ratio showed better agreement with the model.     

Mutational analysis of structure--activity relationships in human tumor necrosis factor-alpha

To determine the region of human tumor necrosis factor-alpha(TNF-), essential for cytotoxic activity against mouse L-M cells,single amino-acid-substituted TNF- mutant proteins (muteins)were produced in Escherichia coli by protein engineering techniques.An expression plasmid for TNF- was mutagenized by passage throughan E.coli mutD5 mutator strain and by oligonucleotide-directedmutagenesis. Approximately 100 single amino-acid-substitutedTNF- muteins were produced and assayed for cytotoxic activity.The cytotoxic activities of purified TNF- muteins, e.g. TNF-31T,-32Y, -82D, -85H, -115L, -141Y, -144K and -146E, were < 1%of that of parent TNF-. These results indicate that the integrityof at least four distinct regions of the TNF- molecule is requiredfor full biological activity. These regions are designated asfollows: region I, from position 30 to 32; region II, from position82 to 89; region III, from position 115 to 117; region FV, fromposition 141 to 146. In addition, TNF-141Y could not completelycompete with parent TNF- for binding to the receptor. This demonstratesthat region IV, and at least aspartk acid at position 141, mustbe involved in the TNF receptor binding site.     

Photo-induced radicals in glucose and cellobiose

Photo-induced radicals in glucose and cellobiose, the model compounds of cellulose molecule, were studied by ESR spectrometry. Very poor formation of radicals in glucose as compared to those in cellobiose was observed. However, a spectrum showing a singlet line was easily produced by the use of light involving shorter wavelengths. It was estimated to be due to the radical formed at the reducing C₁ position of glucose molecule. By paper chromatography, the photo-irradiated cellobiose was confirmed to split into glucose through scission of glucosidic bonds in the molecule. The ESR spectrum of the acid-hydrolyzed cellulose similar to that of the unhydrolyzed sample was a seven-line spectrum, but the relative signal intensity was here markedly low. This phenomenon seems to be caused by the reduction of amorphous portion in the samples due to acid hydrolysis. It was concluded that the glucosidic bonds in cellobiose and cellulose molecules are very active toward light and play an important role in the radical formation in photo-irradiated samples.     

Correlations of Hepatic Hemodynamics,Liver Function,and Fibrosis Markers in Nonalcoholic Fatty Liver Disease: Comparison with Chronic Hepatitis Related to Hepatitis C Virus

The progression of chronic liver disease differs by etiology. The aim of this study was to elucidate the difference in disease progression between chronic hepatitis C (CHC) and nonalcoholic fatty liver disease (NAFLD) by means of fibrosis markers, liver function, and hepatic tissue blood flow (TBF). Xenon computed tomography (Xe-CT) was performed in 139 patients with NAFLD and 152 patients with CHC (including liver cirrhosis (LC)). The cutoff values for fibrosis markers were compared between NAFLD and CHC, and correlations between hepatic TBF and liver function tests were examined at each fibrosis stage. The cutoff values for detection of the advanced fibrosis stage were lower in NAFLD than in CHC. Although portal venous TBF (PVTBF) correlated with liver function tests, PVTBF in initial LC caused by nonalcoholic steatohepatitis (NASH-LC) was significantly lower than that in hepatitis C virus (C-LC) (p = 0.014). Conversely, the liver function tests in NASH-LC were higher than those in C-LC (p < 0.05). It is important to recognize the difference between NAFLD and CHC. We concluded that changes in hepatic blood flow occurred during the earliest stage of hepatic fibrosis in patients with NAFLD; therefore, patients with NAFLD need to be followed carefully.     

Finishing characteristics of brittle materials by ELID-lap grinding using metal-resin bonded wheels

ELID-lap grinding is a method of constant pressure grinding which utilizes an electrically conductive wheel and the electrolytic in-process dressing (ELID) method. This method has the advantage of using micro grain-wheels above #10 000 and also, through simple modification, can be used on existing lap machines. To find the characteristics of metal-resin bonded wheels developed for ELID-lap grinding, experiments on the grinding of brittle materials were performed using wheels with a variety of grain diameters. The wheels used in the experiments were #8000, #120 000 and #3 000 000 metal-resin bonded diamond wheels (#8000 MRB-D, #120 000 MRB-D and #3 000 000 MRB-D wheels). The workpieces were silicon and glass. The results of the experiments showed that stable grinding can be achieved with the #8000 to #3 000 000 MRB-D wheels. With the #3 000 000 MRB-D wheel, very smooth surface finishes were obtained for both silicon (PV 2.8 nm) and glass (PV 2.5 nm). Atomic Force Microscope (AFM) and Scanning Electron Microscope (SEM) observations indicated these surfaces to be very smooth in the order of several nanometers, obtained by mechanical removal using an ultrafine wheel.     

Effect of water on vapor phase photografting on cellulose and its derivatives

Effect of water on vapor phase photografting on cellulose was investigated at 60°C. An activated grafting of methyl methacrylate by water contained in the sample was observed in the experiment. The effect of water was commonly recorded irrespective of the type of cellulose derivatives such as cellulose acetate (degree of substitution, DS = 0.18 and 0.33), cellulose nitrate (DS = 0.35 and 0.75), and carboxymethl cellulose (DS = 0.19 and 0.74). Organic solvents can also be used in place of water, indicating that the percent grafting decreases in the order, water > methanol > acetone > cyclohexane. From ESR studies, water in the sample was found to contribute to the decay of cellulose radicals rather than to the radical formation. The decay was accelerated by organic solvents, and the magnitude of the effect was in the order, water ≈ methanol > acetone > cyclohexane. Based on the above investigation, it was presumed that water contained in the sample cannot contribute directly to the formation of cellulose radicals which may initiate grafting, but mostly promotes the penetration of monomer into cellulose fibers. Such penetration could lead cellulose radicals to an effective initiation of grafting.     

Sterols,methylsterols, and triterpene alcohols in threeTheaceae and some other vegetable oils

The unsaponifiables from threeTheaceae (Camellia japonica L.,Camellia Sasanqua Thunb., andThea sinensis L.) oils and alfalfa, garden balsam, and spinach seed oils and shea fat were separated into four fractions: sterols, 4-methylsterols, triterpene alcohols, and less polar compounds by thin layer chromatography. While the sterol fraction was the major one for the unsaponifiables from alfalfa and spinach seed oils, the triterpene alcohol fraction was predominant for the unsaponifiables from all other oils. The sterol, 4-methylsterol, and triterpene alcohol fractions were analyzed by gas chromatography. All the sterol fractions were alike in their compositions, consisting exclusively of Δ⁷-sterols, such as α-spinasterol and Δ⁷-stigmastenol as predominant components together with Δ⁷-avenasterol and 24-methylcholest-7-enol. Obtusifoliol, gramisterol (occasionally accompanied with cycloeucalenol), and citrostadienol, together with several other unidentified components, were found in the 4-methylsterol fractions from all of the oils except shea fat. The 4-methylsterol fraction from shea fat showed a characteristic composition containing a large proportion of unidentified components which had relative retention time greater than that of citrostadienol, while no citrostadienol was detected. β-Amyrin, lupeol, and butyospermol were major components of the triterpene alcohol fractions from most of the oils, but the fraction from spinach seed oil contained cycloartenol and 24-methylene-cycloartanol as predominant components. There is a close similarity in the compositions of unsaponifiables (sterols, 4-methylsterols, and triterpene alcohols) of the threeTheaceae oils. Two sterols, α-spinasterol and Δ⁷-stigmastenol, and five triterpene alcohols were isolated from tea seed oil. Moreover, five unidentified components beside parkeol, butyrospermol, α-amyrin, and lupeol were isolated from the triterpene alcohol fraction of shea fat.     

Short- and long-term strength characteristics of particulate-filled cast epoxy resin

Particulate-filled thermosetting composites are widely used, yet little systematic work has been done on their long-term strength characteristics. In this study short-term tensile, flexural, and impact tests as well as tensile creep-rupture tests were made for unfilled and filled epoxy to clarify the effects of filler size, filler content, and temperature. Fillers used were silica, alumina particles, and glass beads. Test temperatures were varied from 25 to 110°C. As a result of short-term testing, it was found that the Petch relation held between strength and filler size if brittle fracture occurred, while a strength and filler size if brittle fracture occurred, while a strengthening effect existed when ductile fracture occurred. On creeprupture testing, a strengthening is observed with filler size and content for silica and glass beads. The Arrhenius plot of rupture time for various filler sizes and contents converges to a characteristic point corresponding to the glass transition temperature of the material. Using this relation, a modified Larson-Miller master rupture curve is proposed which can predict the long-term strength of particulate-filled thermosetting composites as functions of rupture time, temperature, filler size, and content.