Evidence for activities inhibiting in trans initiation of DNA replication in extract prepared from irradiated cells

We have previously shown that replication in vitro of plasmids containing the Simian virus 40 (SV40) origin of replication is reduced when an extract of irradiated cells is used (Wang et al., Radiat. Res. 142, 169-175, 1995). We proposed that the observed reduction in the overall replication activity is due to a reduction in the efficiency of initiation events, and that it is caused by the induction or activation by ionizing radiation of a factor(s) that inhibits DNA replication in trans. Here, we extend these studies and provide evidence that the reduced replication activity of an extract prepared from irradiated cells is not the result of a nonspecific inactivation of proteins or of an increase in the requirement for SV40 large tumor antigen (TAg), the only noncellular protein required for in vitro DNA replication. Mixing experiments demonstrate the presence of a dominant inhibitory activity(ies) in the extract of irradiated cells that efficiently stalls replication in reactions assembled using extract of nonirradiated cells. The inhibitory activity is a stable, nondialyzable molecule. Studies of kinetics suggest that the inhibitory activity(ies) affects the initiation steps of DNA replication and acts, at least partly, by modifying TAg, the key initiation protein of SV40 ori DNA replication. It is likely that the same inhibitory activity(ies) regulates cellular DNA replication by modifying the cellular homologues of TAg. Purification and characterization of this inhibitory activity(ies) will contribute to our understanding of the mechanism developed by the cell to regulate DNA replication after exposure to ionizing radiation and will define a checkpoint operating in S phase. Genetic evidence for a checkpoint in S phase distinct from the checkpoints operating in G1 and G2 phase has been reported in yeast.     

Electron beam lithography using chemically-amplified resist: Resolution and profile control

The effect of post exposure bake and softbake conditions on the sensitivity of AZPN114 has been investigated experimentally. A bilayer system for undercut structures has been achieved using two layers of AZPN114 with different softbake temperatures. A single layer of AZPN114 has also been used to produce undercut and tailored resist profiles by two different multiple exposure strategies at different beam energies.     

Fracture toughness measurements on SiC/Al2O3 composite

Three test techniques are addressed for the measurements of plane strain critical stress intensity factors,K _IC, on monolithic Al₂O₃ and SiC-whisker/Al₂O₃ composite: a four-point test on chevron-notched bend bars; a four-point test on single edge-notched bend bars; and a fractometric test on chevron-notched short bars. The tests were performed on 99.80% Al₂O₃ and 30 vol % SiC whisker-reinforced Al₂O₃. Bend bar test techniques yielded more realistic stress intensity factors,K _IC, on the SiC-whisker/Al₂O₃ composite than the short-bar test results. Chevron-notched bend-bar tests yielded relatively higher critical stress intensity factors, on both Al₂O₃ and SiC/Al₂O₃, possibly due toR-curve effects, suggesting the use of stress intensity factor as a function of crack length instead of using the minimum value. Ambiguous results,K _IC, obtained from short-bar tests on SiC/Al₂O₃ composite, strongly suggests the need to run compliance calibration tests on ceramic composites to determine an appropriateK-factor.     

Heat loss factor of evacuated tubular receivers

Tubular receivers with an evacuated space between the absorber and concentric glass cover to suppress convection heat loss are employed as absorbers of linear concentrators in the intermediate temperature range. A knowledge of their heat loss factor is important for a study of the thermal performance of such solar concentrating systems. The heat loss factor of a collector can be calculated by solving the governing heat transfer equations or estimated from an empirical equation, if available. The governing equations must be solved simultaneously by iterations, but this is tedious and cumbersome. Although several correlations exist for determining the heat loss factor for flat-plate collectors and non-evacuated tubular absorbers of linear solar collectors, there is no available correlation for predicting the heat loss factor of evacuated receivers.

A correlation to calculate the heat loss factor (U_L) of evacuated tubular receivers as a function of variables involved (absorber temperature, emittance, diameter and wind loss coefficient) has been obtained. The correlation developed by a least square regression analysis predicts the heat loss factor to within ±1.5% of the value obtained by exact solution of the simultaneous equations in the following range of variables: wind loss coefficient, 10–60 W/m²°C; emittance, 0.1–0.95; and absorber temperature, 50–200°C.     

Spectral investigation and laser action in solid films of fluorene-dibenzothiophene-s,s-dioxide co-polymers

A systematic optical study of a series of 9,9–dyoctylefluorene-2,7-diyl-dibenzothiophene-s,-s-dioxide-3,7-diyl co-polymers p(F-S)y has been performed where S unit (-dibenzothiophene-s,sdioxide-3,7diyl) varied from 15 to 50 mol%. We have investigated optical absorption, steady state and time resolved photoluminescence spectroscopy at room temperature and at low temperature. The emission band for all of these materials is red shifted from that of poly(9,9-dioctylfluorene). Except for p(F-S)50 all our material show one phosphorescence band at low temperature. Dual phosphorescence is observed for p(F-S)50 that are originated from different monomer units. Drop cast film of p(F-S)50 shows amplified spontaneous emission (ASE) effect peaking at 2.66 eV with FWHM at 5 nm.     

Investigating the Effect of Process Parameter on the Properties of Rf Sputtered pSi Thin Film by Taguchi and ANOVA Analysis

Silicon - Boron doped pSi was deposited on Si substrate in the RF magnetron sputtering system by varying three process parameters, namely-sputtering power, working pressure, and Ar gas flow rate....     

Ecofriendly Synthesis of Silver Nanoparticles by Terrabacter humi sp. nov. and Their Antibacterial Application against Antibiotic-Resistant Pathogens

It is essential to develop and discover alternative eco-friendly antibacterial agents due to the emergence of multi-drug-resistant microorganisms. In this study, we isolated and characterized a novel bacterium named Terrabacter humi MAHUQ-38^T, utilized for the eco-friendly synthesis of silver nanoparticles (AgNPs) and the synthesized AgNPs were used to control multi-drug-resistant microorganisms. The novel strain was Gram stain positive, strictly aerobic, milky white colored, rod shaped and non-motile. The optimal growth temperature, pH and NaCl concentration were 30 °C, 6.5 and 0%, respectively. Based on 16S rRNA gene sequence, strain MAHUQ-38^T belongs to the genus Terrabacter and is most closely related to several Terrabacter type strains (98.2%–98.8%). Terrabacter humi MAHUQ-38^T had a genome of 5,156,829 bp long (19 contigs) with 4555 protein-coding genes, 48 tRNA and 5 rRNA genes. The culture supernatant of strain MAHUQ-38^T was used for the eco-friendly and facile synthesis of AgNPs. The transmission electron microscopy (TEM) image showed the spherical shape of AgNPs with a size of 6 to 24 nm, and the Fourier transform infrared (FTIR) analysis revealed the functional groups responsible for the synthesis of AgNPs. The synthesized AgNPs exhibited strong anti-bacterial activity against multi-drug-resistant pathogens, Escherichia coli and Pseudomonas aeruginosa. Minimal inhibitory/bactericidal concentrations against E. coli and P. aeruginosa were 6.25/50 and 12.5/50 μg/mL, respectively. The AgNPs altered the cell morphology and damaged the cell membrane of pathogens. This study encourages the use of Terrabacter humi for the ecofriendly synthesis of AgNPs to control multi-drug-resistant microorganisms.     

An electrochemical microfluidic platform for human P450 drug metabolism profiling

This paper is the first report of a P450-electrode in a microfluidic format. A 30 μL microfluidic cell was made in poly(methyl methacrylate) containing the inlet, outlet, and reaction chamber with two electrode strips, one of which contains the human cytochrome P450 3A4 covalently bound to gold via a 6-hexanethiol and 7-mercaptoheptanoic acid (1:1) self-assembled monolayer. The electrochemical response of the P450-electrode in the microfluidic cell was tested using four drugs that are known substrates of P450 3A4: quinidine, nifedipine, alosetron and ondansetron. Titration experiments allowed the electrochemical measurements of K(M) for the four drugs, with values of 2.9, 29.1, 113.4, and 114.1 mM, respectively. The K(M) values are found to be in good agreement and correctly ranked with respect to the published literature on human liver microsomes and baculosomes: [ondansetron ≈ alosetron > nifedipine > quinidine]. The results presented in this paper represent a step forward for a rapid evaluation of the interaction of P450 and drug, requiring small volumes of new chemical entities to be tested.     

Computerized tolerance techniques

The intense global competition to produce quality product at low cost has led many industrial nations to consider mechanical tolerances as a key factor to bring about cost savings as well as be competitive. In the last two decades, not enough research work has been done in the area of tolerance techniques. In this paper, a comprehensive summary of the state of the art and the projection of future trends in tolerance techniques is presented to help make a decision concerning the improvement techniques today and to aid in guiding research for the future. This paper reviews the status of theory and practice about how manufacturing and assembly processes are characterized for relating tolerances to process or production cost. The specification of tolerancing on the dimension of the manufactured part has a significant impact on the final production cost. Tight tolerances can result in excessive process cost, while loose tolerances may lead to increased waste and assembly problems. This paper systematically reviews the state of art by classifying the papers written so far into three categories. The categories are tolerance chain technique, tolerances based on analysis and synthesis, and tolerances based on cost-tolerance algorithms and design methods. Future areas of research and the unresolved issues have been presented that will serve as a guiding light for the researcher to investigate and bring about the solution in future.