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The results have been achieved by adjusting the structure to improve the performance of micro injection molded isotactic polypropylene products. Annealing was adopted to optimize the performance of isotactic polypropylene micro injection molded gears. It was found that the annealing temperature shows greater influence on the crystalline structure of the micro injection molded gears than annealing time. The layer mechanical properties were greatly improved after annealing, about 1.7-fold for modulus and 1.9-fold for hardness of the micro injection molded gears relative to the unannealed sample. This is due to the fact the state of molecular chain aggregation tends to be consistent after high temperature annealing in the micro injection molded isotactic polypropylene gear sample.

This paper focuses on land use as the primary variable for transit ridership estimation, with 100 000 points of interest (POIs) in Beijing being extracted from a digital map and classified into five categories according to main transit trip purposes. To better quantify the characteristics of the land surrounding a transit station and further assist sustainable zoning, a multi-level catchment area delineation method that includes pedestrian, traffic, and potential areas is applied. The built areas of different categories of POIs within various catchment areas are used to describe precise land use characteristics of 24 randomly selected transit stations in Beijing. A direct ridership model that involved land use characteristics is developed and combined with the ridership calculated using Beijing transit auto fare collection (AFC) data. Model validation with 10 other randomly selected stations meets initial expectations, indicating that the proposed model has the potential for use to provide a quantitative link between land use and travel demand.

Based on the different nucleation ability, different contents and proportions of the mixed nucleating agents were melt compounded with pure isotactic polypropylene resins employed in this work, selective ß nucleating agent was a compound of pimelic acid and calcium stearate, the a nucleating agent was a type of dibenzylidene sorbitol derivative. The competition attributed to the different type of interactions between a nucleating agent and isotactic polypropylene molecular chains during crystallization was investigated in this research. For a low content of the mixed nucleating agents used, a nucleation dominated the crystallization behavior of isotactic polypropylene, while with an increase of the content of the mixed nucleating agents, the situation was reversed and ß nucleation became dominant. In the ß dominated region, both of the molecular chain and segmental motions were various with different nucleating agent proportion. Thus, the content and proportion of the components of the nucleating agents were the critical factors in the competition during crystallization.

A general set of quantitative model assessment and analysis tools, termed high-dimensional model representations (HDMR), has been introduced recently for improving the efficiency of deducing high-dimensional input−output system behavior. HDMR is a particular family of representations where each term in the representation reflects the independent and cooperative contributions of the inputs upon the output. When data are randomly sampled, a RS (random sampling)-HDMR can be constructed. To reduce the sampling effort, different analytical basis functions, such as orthonormal polynomials, cubic B splines, and polynomials may be employed to approximate the RS-HDMR component functions. Only one set of random input−output samples is necessary to determine all the RS-HDMR component functions, and a few hundred samples may give a satisfactory approximation, regardless of the dimension of the input variable space. It is shown in an example that judicious use of orthonormal polynomials can provide a sampling saving of ~10³ in representing a system compared to employing a direct sampling technique. This paper discusses these practical approaches:  their formulas and accuracy along with an illustration from atmospheric modeling.

We are studying the molecular organization of protein arrays using two-dimensional streptavidin crystals bound to biotinylated lipid monolayers at the air−water interface. We constructed a mutant form of the streptavidin protein that successfully alters the molecular organization of the streptavidin crystals. Cocrystallization of streptavidin carrying this single targeted point mutation with wild-type streptavidin yields two-dimensional crystals displaying a chiral morphology with molecular coexistence, indicating a solid-phase transition. The phase coexistence and resulting morphologies are reminiscent of two-dimensional crystal behavior of wild-type streptavidin near its isoelectric point, and this analogy is discussed. These results demonstrate the potential to manipulate protein array formation through point mutagenesis and cocrystallization.

math5 is a murine orthologue of atonal, a bHLH proneural gene essential for the formation of photoreceptors and chordotonal organs in Drosophila. The expression of math5 coincides with the onset of retinal ganglion cell (RGC) differentiation. Targeted deletion of math5 blocks the initial differentiation of 80% of RGCs and results in an increase in differentiated amacrine cells. Furthermore, the absence of math5 abolishes the retinal expression of brn-3b and the formation of virtually all brn-3b-expressing RGCs. These results imply that math5 is a proneural gene essential for RGC differentiation and that math5 acts upstream to activate brn-3b-dependent differentiation processes in RGCs.

The carboxyl- and amino-terminal ends of streptavidin are near the site of protein−protein contacts in two-dimensional streptavidin crystals. The role of these C- and N-terminal residues in determining the pH-dependent phase behavior of crystallization has been investigated with site-directed truncation mutants. Commercial streptavidin (consisting primarily of amino acids 14−136) and two recombinant streptavidin forms, spanning residues 13−136 and 13−139, have been crystallized at pH 4−7. The commercial 14−136 protein crystallizes in three distinct lattice symmetries, P1, P2, and C222, respectively, depending on pH. The 13−136 mutant also crystallizes in three distinct lattices, but with a shifted pH profile that is attributed to the N-terminal residue. The presence of amino acids 137−139 inhibits the growth of crystals with P1 symmetry at low pH. In addition, we observe a solid−solid phase transition in situ from the P2 to the P1 crystal forms for the 13−136 recombinant protein at pH 5.2. We also demonstrate the ability of Brewster angle microscopy to distinguish between different crystal forms if protein monolayer densities are sufficiently different.

The replication checkpoint (or 'S-M checkpoint') control prevents progression into mitosis when DNA replication is incomplete. Caffeine has been known for some time to have the capacity to override the S-M checkpoint in animal cells. We show here that caffeine also disrupts the S-M checkpoint in the fission yeast Schizosaccharomyces pombe. By contrast, no comparable effects of caffeine on the S. pombe DNA damage checkpoint were seen. S. pombe cells arrested in early S phase and then exposed to caffeine lost viability rapidly as they attempted to enter mitosis, which was accompanied by tyrosine dephosphorylation of Cdc2. Despite this, the caffeine-induced loss of viability was not blocked in a temperature-sensitive cdc2 mutant incubated at the restrictive temperature, although catastrophic mitosis was prevented under these conditions. This suggests that, in addition to S-M checkpoint control, a caffeine-sensitive function may be important for maintenance of cell viability during S phase arrest. The lethality of a combination of caffeine with the DNA replication inhibitor hydroxyurea was suppressed by overexpression of Cds1 or Chk1, protein kinases previously implicated in S-M checkpoint control and recovery from S phase arrest. In addition, the same combination of drugs was specifically tolerated in cells overexpressing either of two novel S. pombe genes isolated in a cDNA library screen. These findings should allow further molecular investigation of the regulation of S phase arrest, and may provide a useful system with which to identify novel drugs that specifically abrogate the checkpoint control.

We studied the molecular arrangement of two-dimensional streptavidin crystals at the air−water interface over a range of pH values. We quantified the varying amounts of coexisting P1, P2, and C222 crystals in the different morphologies observed at pH 4.5−6.5. Chiral, needlelike crystals at pH 4.5 consist of P1 crystals with frequent line defects. Larger chiral domains near pH 5 are essentially all P1 coexisting with a small amount of P2, whereas at slightly higher pH values (near pH 5.5), H-shaped domains contain 4 times as much P1 coexisting with a P2/C222 mixture. Morphologies intermediate to these shapes exhibit intermediate compositions. Between pH ~6−7, crystals all display a characteristic dendritic-X morphology, but arrangement at the molecular level is quite different compared with lower pH values. Crystals are mostly P2 in symmetry near pH 6, but at pH 7 and above, crystals have C222 symmetry. Coexistence of P2 and C222 crystals occurs at intermediate pH values. We determined the orientation and arrangement of streptavidin molecules in P1, P2, and C222 crystals relative to the directions exhibiting faster growth. The direction of faster growth in P1 crystals includes both interactions between biotin-free subunits and interactions between biotin-bound subunits. In the P2 arrangement, growth in the direction of intermolecular biotin-free subunits is preferred, whereas growth is faster along the biotin-bound direction of C222 crystals. We developed a model of the molecular arrangement for the observed solid-phase coexistence in these crystals.

Topoisomerases catalyse changes in the topological state of DNA and are required for many aspects of DNA metabolism. While the functions of topoisomerases I and II in eukaryotes are well established, the role of topoisomerase III remains poorly defined. We have identified a gene in the fission yeast Schizosaccharomyces pombe, designated top3 (+), which shows significant sequence similarity to genes encoding topoisomerase III enzymes in other eukaryotic species. In common with murine TOP3 alpha, but in contrast to Saccharomyces cerevisiae TOP3, the S.pombe top3 (+)gene is essential for long-term cell viability. Fission yeast haploid spores containing a disrupted top3 (+)gene germinate successfully, but then undergo only a limited number of cell divisions. Analysis of these top3 mutants revealed evidence of aberrant mitotic chromosome segregation, including the 'cut' phenotype, where septation is completed prior to nuclear division. Consistent with the existence of an intimate association (originally identified in S.cerevisiae ) between topoisomerase III and DNA helicases of the RecQ family, deletion of the rqh1 (+)gene encoding the only known RecQ helicase in S.pombe suppresses lethality in top3 mutants. This conservation of genetic interaction between two widely diverged yeasts suggests that the RecQ family helicases encoded by the Bloom's and Werner's syndrome genes are likely to act in concert with topoisomerase III isozymes in human cells. Our data are consistent with a model in which the association of a RecQ helicase and topoisomerase III is important for facilitating decatenation of late stage replicons to permit faithful chromosome segregation during anaphase.

Many applications motivate investigations of the physical factors governing protein assembly in two dimensions, including two-dimensional (2D) protein crystallization for complex structural analyses and the development of technologies such as biosensors and engineered biomaterials. In addition, 2D macromolecular ordering is of fundamental interest in the areas of phase behavior and complex fluids. Our work involves the growth of 2D streptavidin crystals to examine protein self-assembly at an interface. Streptavidin molecules bound to a biotinylated lipid monolayer self-assemble into ordered arrangements, creating 2D crystals with distinct macroscopic morphologies and lattice configurations. In this paper, we highlight previous work examining the effects of intermolecular interactions on molecular organization and macroscopic properties in ordered protein arrays. We also describe our recent progress using streptavidin mutants to study specific protein−protein interactions and their effects on crystal properties. We show that specific changes in intermolecular interactions give alternate morphological, crystallographic, and thermodynamic properties in ordered monolayers. We introduce an additional growth direction in a crystal with oblique P1 symmetry by engineering extra hydrogen bonds. These extra interactions kinetically trap the crystal in a less-ordered paracrystalline state; however, a solid−solid phase transition to the more-ordered, thermodynamically favored form occurs over time. Removal of this interaction enables molecules to directly form the more-ordered P1 configuration. The introduction of repulsive forces at this site inhibits P1-crystal formation such that crystals with P2 symmetry grow at conditions normally resulting in P1 crystals. Our results confirm that macrosopic and microscopic changes in 2D crystalline properties can be elicited by selectively altering specific intermolecular interactions. Such specific engineered alterations are useful in producing desired crystals and to further our understanding of protein interactions and assembly.

Acetylene inhibition of N2O reduction to N2is traditionally used to estimate denitrification. Although NO is also produced in the denitrification process, the effect of C2H2on NO production in denitrification has not previously been examined, mainly because C2H2interferes with chemiluminescent analysis of NO. We used a gas‐flow system to study the effect of C2H2on NO and N2O production in soil columns under denitrifying conditions and developed a method to avoid C2H2interference of NO analysis. Nitric oxide, N2O, and C2H2were measured in NO−3‐amended Brookston clay loam (fine‐loamy, mixed, mesic Typic Argiaquoll) and Fox sandy loam (fine‐loamy over sandy or sandy‐skeletal, mixed, mesic Typic Hapludalf) with various moisture contents with and without added glucose during 50‐h anaerobic incubations. In glucose‐amended Brookston soil with ≈8% C2H2added to the N2carrier gas, net NO production rates were increasingly inhibited after the first 24 h, and by 50 h were only 2 to 7% of the rates obtained in the absence of C2H2. Without glucose amendment and with C2H2, net NO production rates decreased by 24 to 62% in the Brookston soil. In the Fox soil inhibition occurred almost immediately on C2H2addition and net NO production during 50 h was reduced by 36 to 62% with glucose amendment, and by 65 to 76% without glucose amendment. In most cases, net N2O production rates were decreased by C2H2due to the decrease in production of its precursor, NO, and in some cases, increased due to inhibition of N2O reduction to N2. Our data suggest that the C2H2inhibition method may underestimate total denitrification rates under low water contents or high levels of C substrate.

1. The effect of simultaneous application of chronic muscle stimulation and salbutamol on the expression of mRNAs and proteins normally expressed by fast‐ or slow‐twitch fibres was followed and the effects of changes in protein expression on mechanical performance were evaluated. Chronic low‐frequency stimulation increased the myosin heavy chain (HC)‐I level in the canine latissimus dorsi muscle and simultaneous administration of salbutamol partially blocked this change. Associated with the increase in HC‐I level was a decrease in the velocity of shortening at zero load, VMAX. The change in VMAX was partially blocked by salbutamol. 2. Chronic low‐frequency stimulation increased the levels of slow‐twitch cardiac isoform sarco‐/endoplasmic reticulum Ca(2+)‐ATPase (SERCA2a) and phospholamban mRNA, and SERCA2a and phospholamban protein expression. These changes were associated with an increase in time‐to‐peak tension and a decrease in fusion frequency. Simultaneous administration of salbutamol blocked these changes in protein expression and muscle mechanics. Chronic stimulation of latissimus dorsi decreased the levels of the fast‐twitch isoform of sarco‐/endoplasmic reticulum Ca(2+)‐ATPase (SERCA1a) and increased SERCA2a protein expression and decreased calcium uptake rate by muscle homogenates. These changes were blocked by salbutamol. 3. The loss of latissimus dorsi muscle weight by chronic stimulation was partially blocked by salbutamol.

1. Salbutamol, a beta 2‐agonist, increased the weight of the canine latissimus dorsi muscle. It also increased fusion frequency, and decreased time‐to‐peak tension, half‐relaxation time, and total contraction time. These changes in twitch times and fusion frequency were associated with changes in the levels of proteins expressed in slow‐ and fast‐twitch fibres. Salbutamol decreased the levels of the slow‐twitch cardiac isoform of sarco‐/endoplasmic reticulum Ca(2+)‐ATPase (SERCA2a) and phospholamban proteins, and increased the level of the fast‐twitch isoform of sarco‐/endoplasmic reticulum Ca(2+)‐ATPase (SERCA1a). 2. Changes in the levels of SERCA proteins, particularly SERCA1a, could account for most of the increases in calcium uptake rate observed in homogenates of muscles from the salbutamol‐treated animals and could partially account for the changes in half‐relaxation rates and other twitch times. 3. Changes in the levels of SERCA1a, SERCA2a and phospholamban protein did not always follow changes in the levels of their corresponding mRNAs. Divergence depended upon the SERCA isoform and muscle. The muscles studied were latissimus dorsi and vastus intermedius. 4. Salbutamol did not change the level of myosin heavy chain (HC)‐I isoforms in either muscle, suggesting that it did not increase the proportion of slow‐twitch fibres in these muscles. It did increase the level of HC‐IIx and decrease the level of HC‐IIa isoforms in the latissimus dorsi. Salbutamol did not produce these effects in the vastus intermedius. It is of particular interest that salbutamol changed the relative levels of SERCA proteins in the latissimus dorsi muscle without producing significant change in the level of HC‐I isoform.

Mechanical behaviour studies were conducted on Nicalon SiC/calcium aluminosilicate (CAS) composites. Tensile tests were carried out to study the stress-strain behaviour, as well as to identify the failure mechanisms, of unidirectional and cross-ply SiC/CAS composites. The evolution of the various damage modes and the synergistic effects among them were investigated. The effect of the 90° ply thickness on the damage modes was also determined. The composite stiffness reduction during damage evolution was evaluated. A tensile test specimen was designed for glass and glass-ceramic composites to avoid end-tab shear failure and expensive machining as well as to reduce the effect of bending due to misalignment. The results of this work provide insight into the stress-strain behaviour and damage mechanisms of continuous fibre-reinforced ceramic composites which can be very valuable in design with these materials.

Nitric oxide reacts with C2H2at ambient temperature under aerobic conditions with relatively large quantities of O2present. We used a gas‐flow system at 20°C to determine the extent, if any, of reaction of NO with C2H2under nearly anaerobic conditions with addition of trace (<500 µL L−1) quantities of O2, and to determine whether the process could account for the apparent C2H2inhibition of NO production in soil. Results showed that reaction occurred only when critical trace quantities of O2were present. For example, if [NO] was in the range 0.5 to 2.5 µL L−1, which is typical of concentrations in our soil studies, approximately 200 to 300 µL O2L−1was required before measurable NO loss was observed. The reaction was first order with respect to NO and variable order, becoming zero order, with respect to O2when [O2] exceeded ≈400 µL L−1and maximum NO depletion rates (≈0.01–0.06 µL L−1s−1) were obtained. The effect of C2H2on NO production with addition of O2(≈20–730 µL L−1) in Brookston clay loam (fine‐loamy, mixed, mesic Typic Argiaquoll) and Fox sandy loam (fine‐loamy over sandy or sandy‐skeletal, mixed, mesic Typic Hapludalf) under conditions similar to the gas‐phase studies was also investigated. Depletion of NO in the presence of C2H2vs. [O2] followed the same pattern with similar rates as the gasphase process. A simplified C2H2‐catalyzed scheme for the oxidation of NO to NO2provides a plausible, partial explanation for these results. Since NO depletion requires only trace amounts of O2, the results suggest that in many previous studies involving assays of NO or N2O production based on C2H2inhibition, significant gas‐phase reaction may have occurred leading to serious errors of interpretation.

Since cover crops and intercrops are increasingly used to reduce soil erosion and N loss and provide efficient N utilization, it is important to evaluate the consequences of crop residue to N cycling processes. The objectives of this study were to determine effects of incorporating hairy vetch (HV, Vicia villosaRoth subsp. villosa), red clover (RC, Trifolium pratenseL.), annual ryegrass (ARG, Lolium multiflorumLam.), reed canarygrass (RCG, Phalaris arundinaceaL.), and corn (Zea maysL.) residues on denitrification, dissimilatory NO−3reduction, and N mineralization‐immobilization in a Brookston clay loam (fine‐loamy, mixed, mesic Typic Argiaquoll). A gas flow system was used with 5 or 10 g residue kg−1amended soil. With only anaerobic incubation, all residues stimulated denitrification about equally with net NO and N2O production rates two to three times greater than in the control soil. Ammonium accumulation over the 48‐h anaerobic period was 5 to 11 mg N kg−1. When a 5‐d aerobic incubation preceeded the anaerobic phase, losses of NO + N2O amounted to 5 to 17 times that in the control soil during the anaerobic phase. These losses were: 59.4, 47.1, 25.1, 24.4, 17.6, and 3.5 mg N kg−1for HV, RC, ARG, RCG, corn, and the control, respectively. Mineralization in the HV treatment occurred from the third to the fifth day of the aerobic incubation and NH+4continued to increase during the subsequent 2‐d anaerobic period, reaching 58.4 mg NH+4‐N kg−1. Nitrite accumulated during the anaerobic phase in all treatments, with 46 and 49 mg N kg−1for ARG and HV, respectively, during with the 2‐d aerobic/2‐d anaerobic incubation. With the 5‐d aerobic/2‐d anaerobic incubation, NO−2levels were lower in all but the ARG treatment.

A new method for labeling oligonucleotides was developed to obtain high specific activity of radioactive probes. In an oligonucleotide molecule, two sequences were designed. One sequence, the 5', contains 19 nucleotides and serves as a template for probe synthesis. The second sequence, 3', contains a consensus sequence which forms a Pst I site after forming a complementary strand with the primer. In the presence of E. coli DNA polymerase I (Klenow fragment), α-32P dNTP and other dNTPs, a radioactive labeled oligonucleotide was synthesized by the primer extension method. After Pst I digestion, the probe was different from its template in length by 4 bp and could be separated from each other on urea-polyacrylamide gel electrophoresis (PAGE). A radioactive 01ionucleotide probe with extremely high specific activity up to 1010 dpm/μg could be obtained by the use of this method. The oligonucleotide probes have been used for the detection of the Hb E mutation in this report.

The paper presents three novel distribution-feeder models to simplify complicated distribution-system calculations. These equivalent models are developed to simulate the total series voltage drop at the end of the given feeder accurately, the total copper loss of the given feeder accurately, and a hybrid to simulate both voltage drop and feeder loss accurately. In addition, all of the proposed models are bidirectional. This means that power infeed can be at either end and the model is accurate. In contrast, unidirectional models previously developed are accurate only when power infeed is at the end specified by the model. This feature is important for a modern power-distribution system in which the power infeed of the switched feeder may change from one end to the other during service restoration or feeder reconfiguration. These bidirectional feeder models are illustrated by examples and applied to an actual feeder. The simulation results show that it is possible to reduce many complex feeders to simple equivalent models in the study of feeder-voltage profiles and losses with negligible error, even if the power infeeds of the given feeders are changed.

During early cleavages of Sicyonia ingentis embryos, mitotic spindle orientations differ between blastomeres and change in a predictable manner with each successive mitosis. From 2nd through 7th cleavages, spindles orient at a 90 degrees angle with respect to the spindle of the parent blastomere. Thus, spindle orientation is parallel to the cleavage plane that formed the blastomere. To determine if specific spindle orientations were intrinsic properties of individual blastomeres, we altered blastomere associations and asked how mitotic spindle orientation was affected in successive cleavages using laser scanning confocal microscopy. Linear embryos were constructed by dissociating 4-cell embryos and recombining the blastomeres in a linear array. The ensuing cleavage (3rd embryonic cleavage) of these linear embryos was parallel to the long axis of the embryo, resulting in four parallel pairs of blastomeres which lay in a common plane that was parallel to the substratum. The 4th cleavage produced a linear embryo with the 16 blastomeres arranged in four parallel quartets. Then, in preparation for 5th cleavage, spindles oriented at a 45 degrees angle (not parallel as in normal development) with respect to the previous cleavage plane. When 8-cell linear embryos were separated into linear half-embryos, subsequent spindle orientations were not like those observed for intact 8-cell linear embryos, but rather regressed to the orientation seen in 4-cell linear embryos. We suggest that the reorientation of mitotic spindles during early cleavage of S. ingentis is neither an intrinsic property nor age dependent, but rather is cell contact related. Further, these results in conjunction with observations of non-manipulated embryos suggest that spindle poles (centrosomes) avoid cytoplasmic regions adjacent to where there is cell-cell contact during early development.