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Boron carbide (B4C) is an attractive material for numerous applications including vehicle armor, cutting tools, blasting nozzles, and abrasive powder, owing to its extreme hardness, high melting point, high Young’s modulus, and excellent thermoelectric properties. However, the application of B4C is limited by the high-temperature synthesis process. The present work aims to explore a low-temperature manufacturing process for synthesizing B4C with a small amount of free carbon. Poly(resorcinol borate) with an aromatic structure and high char yield was chosen as the aromatic polymeric precursor. A combination of Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy and Raman spectroscopy was performed to investigate the influences of the reaction temperature and holding time on the changes in the precursor microstructure. The results indicate that the rod-like structure of crystalline B4C is successfully synthesized at 600 °C, and the free carbon can be reduced to about 0.8 wt% in the final product. This is because the pyrolysis temperature controlled the carbon content of the B4C, which led to an enlarged contact domain between B2O3 and carbon, and a relatively low-temperature synthesis of B4C.
Auto-alignment is a basic technique for high-power laser systems. Special techniques have been developed for laser systems because of their differing structures. This paper describes a new sensor for auto-alignment in a laser system, which can also serve as a reference in certain applications. The authors prove that all of the beam transfer information (position and pointing) can theoretically be monitored and recorded by the sensor. Furthermore, auto-alignment with a single lens sensor is demonstrated on a simple beam line, and the results indicate that effective auto-alignment is achieved.
Scabies is a parasitic disease caused by the ectoparasite Sarcoptes scabiei, affecting different mammalian species, including rabbits, worldwide. In the present study, we cloned and expressed a novel inorganic pyrophosphatase, Ssc-PYP-1, from S. scabiei var. cuniculi. Immunofluorescence staining showed that native Ssc-PYP-1 was localized in the tegument around the mouthparts and the entire legs, as well as in the cuticle of the mites. Interestingly, obvious staining was also observed on the fecal pellets of mites and in the integument of the mites. Based on its good immunoreactivity, an indirect enzyme-linked immunosorbent assay (ELISA) using recombinant Ssc-PYP-1 (rSsc-PYP-1) as the capture antigen was developed to diagnose sarcoptic mange in naturally infected rabbits; the assay had a sensitivity of 92·0% and specificity of 93·6%. Finally, using the rSsc-PYP-1-ELISA, the Ssc-PYP-1 antibody from 10 experimentally infected rabbits could be detected from 1 week post-infection. This is the first report of S. scabiei inorganic pyrophosphatase and the protein could serve as a potential serodiagnostic candidate for sarcoptic mange in rabbits.
Recent studies have indicated that widespread wastage of glaciers in western China has occurred since the late 1970s. By using digitized glacier outlines derived from the 1970 inventory and Landsat satellite data from 1990/91 to 2001, we obtained area changes of about 278 glaciers with a total area of 2711.57 km2 in the heavily glaciated west Kunlun Shan (WKS) in the northern Tibetan Plateau (TP). Results indicate that the prevailing characteristic of glacier variation is ice wastage, and glacier area decreased by 10 km2 (0.4% of the total 1970 area) between 1970 and 2001. Both the south and north slopes of the WKS presented shrinkage during 1970–2001, but whereas on the north slope a slight enlargement of ice extent during 1970–90 was followed by a reduction of 0.2% during 1990–2001, on the south slope the glacier area decreased by 1.2% during 1970–91, with a small increment of 0.6% during 1991–2001. Comparisons with other glaciated mountainous regions in western China show that glaciers in the research area have experienced less retreat. Based on records from the Guliya ice core, we believe that an increase in air temperature was the main forcing factor for glacier shrinkage during 1970–2001.
Previous studies have supported the theory that there is a positive association between ferritin and carotid atherosclerosis in Western people. Diet plays an important role in determining serum ferritin concentration. Asian dietary patterns are different from Western dietary patterns, implying that there may be a difference in the association of ferritin with carotid atherosclerosis between Asian and Western people. However, few studies focus on the association between ferritin and carotid atherosclerosis among Asians. The aim of this study was to investigate how serum ferritin levels are associated with carotid atherosclerosis in an Asian adult population. A cross-sectional assessment was performed in 8302 adults in Tianjin, China. Carotid intima-media thickness (IMT) and plaques were assessed using ultrasonography, and serum ferritin was measured using the protein chip-chemiluminescence method. Multiple logistic regression analysis was used to examine the association between quartiles of serum ferritin concentration and carotid atherosclerosis. In the present study, the overall prevalence of IMT and carotid plaques in participants is 29·2 and 22·7 %, respectively. In women, after adjustments for potentially confounding factors, the OR of IMT and carotid plaques by increasing serum ferritin quartiles were 1·00, 1·39 (95 % CI 0·98–1·99), 1·39 (95 % CI 0·99–1·97), 1·81 (95 % CI 1·30–2·55) (Pfor trend<0·001) and 1·00, 1·24 (95 % CI 0·89–1·73), 1·18 (95 % CI 0·85–1·65), 1·59 (95 % CI 1·15–2·20) (Pfor trend<0·01), respectively. However, no association was found between serum ferritin and carotid atherosclerosis in men. The study demonstrated that increased serum ferritin levels are independently associated with IMT and carotid plaques in Asian women but not in Asian men.
In recent decades, in silico absorption, distribution, metabolism, excretion (ADME), and toxicity (T) modelling as a tool for rational drug design has received considerable attention from pharmaceutical scientists, and various ADME/T-related prediction models have been reported. The high-throughput and low-cost nature of these models permits a more streamlined drug development process in which the identification of hits or their structural optimization can be guided based on a parallel investigation of bioavailability and safety, along with activity. However, the effectiveness of these tools is highly dependent on their capacity to cope with needs at different stages, e.g. their use in candidate selection has been limited due to their lack of the required predictability. For some events or endpoints involving more complex mechanisms, the current in silico approaches still need further improvement. In this review, we will briefly introduce the development of in silico models for some physicochemical parameters, ADME properties and toxicity evaluation, with an emphasis on the modelling approaches thereof, their application in drug discovery, and the potential merits or deficiencies of these models. Finally, the outlook for future ADME/T modelling based on big data analysis and systems sciences will be discussed.
We have examined the structure of plastic deformation zones ahead of the tips of microcracks in Zr-based bulk metallic glass Zr57Ti5Cu20Ni8Al10. We have used an axially aligned dark field transmission electron microscopy technique, with the objective aperture placed to form images using electrons from several different areas of the diffraction patterns. We also compared Fourier transforms of the high resolution transmission electron microscopy images of deformed and undeformed regions to extract additional structural information. The plastic zones produce enhanced low-angle scattering of electrons and an apparent broadening of the amorphous halo, suggesting increased disorder and the presence of voids in the deformed zones. These results are consistent with an increased degree of atomic-scale disorder and enhanced free volume in highly deformed regions, which may provide a partial explanation of the manner in which plastic deformation occurs in metallic glasses.
Many types of procedures have been developed for testing of the chemical durability of nuclear waste forms. These procedures differ from each other in critical aspects, such as duration, replenishment or non-replenishment of the leachates, and S/V ratio. As a result, different answers to basic questions, such as how waste-form leachability depends on its chemical composition, are obtained when different test methods are used. Furthermore, the possibility that some glasses may exhibit a leach rate excursion within the test period causes the composition dependence to be an even more sensitive function of test duration and of leachant replenishment. These factors also complicate the use of test data for the prediction of long-term waste form behavior.
In situ X-raydiffraction measurements on almandine, (Fe0.86Mg0.07Mn0.07)3Al2Si3O12, were performed using a heating diamond-anvil cell instrument with synchrotron radiation at Beijing Synchrotron Radiation Facilityup to 27.7 GPa and 533 K. The pressure-volume-temperature data were fitted to a third-order Birch-Murnaghan equation of state. The isothermal bulk modulus of K0 = 177±2 GPa, a temperature derivative of the bulk modulus of (∂K/∂T)P= –0.032±0.016 GPaK–1 and a thermal expansion coefficient (α0) of (3.1±0.7)×10–5 K–1 were obtained. This is the first time that the temperature derivative of the bulk modulus of almandine has been determined at high pressure and high temperature. Combining these results with previous results, the compositional dependence of the bulk modulus, thermal expansion, and temperature derivative of the bulk modulus are discussed.
Nine prepubertal gilts (JunMu No. 1) were randomly allocated into three groups (n=3) and fed with a high-energy diet (Group H), a low-energy diet (Group L), or a moderate-energy diet (Group M) for 14 days. Free access to water was provided throughout the research period. Ovaries and uteri were collected after the energy treatments, and processed for determination of the absolute quantities of insulin-like growth factor receptor (IGF-1R) and epidermal growth factor receptor (EGFR) mRNA, using real-time polymerase chain reaction (PCR). The expression of IGF-1R and EGFR mRNA in ovaries and uteri was significantly ranked as: Group H>Group M>Group L (P<0.05). This result suggests that high energy intake markedly enhanced the ovarian and uterine expression of IGF-1R and EGFR in prepubertal gilts, whereas insufficient energy intake markedly inhibited such expression. IGF-1R and EGFR may be involved in mediating the effects of energy intake on the development of the reproductive system in prepubertal gilts.
The RNA-dependent RNA polymerase (RdRp) gene of Bombyx mori cypovirus 1 (BmCPV-1) (China strain) was cloned in three fragments using step-by-step reverse transcriptase-polymerase chain reaction (RT-PCR). The whole RdRp gene of 3691 bp was sequenced (GenBank accession number: AY496445). Vector pET-28b(+) was used to construct the expression vector pET28b–RdRp which was expressed in Escherichia coli BL21 (DE3) induced with isopropyl β-d-thiogalactoside (IPTG). The molecular weight of the expression product was about 138 Da. The primary antibody employed was rabbit antibody against BmCPV–RdRp recombinant protein and the secondary antibody was 15 nm immunogold-labelled goat anti-rabbit IgG. Immunogold was mostly bound to the virions which were dispersed in a virus generation matrix and polyhedron in the columnar cells of the midgut of the silkworms, and the average marking ratio was about 35%. This result demonstrated that BmCPV–RdRp complexes are indeed located at the BmCPV capsid.
There are four known species of Isoetes (Family Isoetaceae) from China: I. hypsophila, I. sinensis and I. yunguiensis on the mainland, and I. taiwanensis on Taiwan. In a 4-year study we documented the distribution and habitat characteristics of all four species and evaluated their conservation status using IUCN criteria. All four species are facing a high risk of extinction and should be categorized as Critically Endangered on the IUCN Red List. Habitat degradation and loss, water pollution and eutrophication, competitive exclusion, and human disturbance are the main factors causing the decline and extirpation of Isoetes. Only I. taiwanensis is protected in situ in Yangmingshan National Park on Taiwan. None of the species or habitats of Isoetes on mainland China are presently protected, although all species have been designated by the government as State Key Protected Wild Plants. Our results suggest that conservation strategies should be implemented urgently, particularly on the mainland.
Ribonuclease P (RNase P) catalyzes the 5′
maturation of precursor tRNA transcripts and, in bacteria,
is composed of a catalytic RNA and a protein. We investigated
the oligomerization state and the shape of the RNA alone
and the holoenzyme of Bacillus subtilis RNase
P in the absence of substrate by synchrotron small-angle
X-ray scattering and affinity retention. The B. subtilis
RNase P RNA alone is a monomer; however, the scattering
profile changes upon the addition of monovalent ions, possibly
suggesting different interdomain angles. To our surprise,
the X-ray scattering data combined with the affinity retention
results indicate that the holoenzyme contains two RNase
P RNA and two RNase P protein molecules. We propose a structural
model of the holoenzyme with a symmetrical arrangement
of the two RNA subunits, consistent with the X-ray scattering
results. This (P RNA)2(P protein)2
complex likely binds substrate differently than the conventional
(P RNA)1(P protein)1 complex; therefore,
the function of the B. subtilis RNase P holoenzyme
may be more diverse than previously thought. These revisions
to our knowledge of the RNase P holoenzyme suggest a more
versatile role for proteins in ribonucleoprotein complexes.
By integrating the truncated complex scalar gravitational motion equations for an anelastic, rotating, slightly elliptical Earth, the complex frequency dependent Earth transfer functions are computed directly. Unlike the conventional method, the effects of both oceanic loads and tidal currents are included via outer surface boundary conditions, all of which are expanded to second order in ellipticity. A modified ellipticity profile in second order accuracy for the non-hydrostatic Earth is obtained from Clairaut’s equation and the PREM Earth model by adjusting both the ellipticity of the core-mantle boundary and the global dynamical ellipticity to modern observations. The effects of different Earth models, anelastic models, and ocean models are computed and compared. The atmospheric contributions to prograde annual, retrograde annual and retrograde semiannual nutation are also included as oceanic effects. Finally, a complete new nutation series of more than 340 periods, including in-phase and out-of-phase parts of longitude and obliquity terms, for a more realistic Earth, is obtained and compared with other available nutation series and observations.
The tolerance of the oocyte plasma membrane (oolemma) to electrical pulses (TEP) was investigated for oocytes, zygotes, and embryos at the early and late 2-cell stage. The oocyte survival rate after two electrical pulses (1.4KV/cm for 640μs each) was used as an indicator of the TEP of the oolemma. Survival rate of mid-pronuclear zygotes (94.3%±2.3%) was significantly (p < 0.05) higher than that of recently ovulated (2.1%±1.9%) and in vivo aged (25.1%±2.6%) oocytes; survival rate of in vivo aged oocytes was also significantly higher than that of recently ovulated oocytes. Soon after fertilisation, the survival rate of the oocytes markedly increased, up to 94% at the mid-pronuclear stage. Survival ratedropped thereafter. These results suggest that the characteristics of the oocyte plasma membrane (oolemma) change after fertilisation.
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