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Biological hydrogel is important in drug delivery system and tissue engineering. In this paper, we prepared a series of biological hydrogels with N,O-carboxymethyl chitosan (CS) and oxidized safflower and ligusticum wallichii polysaccharide-II (oxidized SLWP-II). Morphological analysis indicated the N,O-carboxymethyl CS/oxidized SLWP-II hydrogels (CSLHs) had porous interior structures, pore diameter ranged from tens to hundreds of micrometers. In vitro release test showed, with proportion of N,O-carboxymethyl CS to oxidized SLWP increasing from 1:1 to 1:3, cumulative release of bovine serum albumin decreased from 99 to 82%. In vitro cytotoxicity study showed that the developed hydrogels were not cytotoxic during one week of culturing with WI-38 cells, and they have a role in promoting cell proliferation. So the N,O-carboxymethyl CS/oxidized safflower and ligusticum wallichii polysaccharide-II hydrogels might have potential application in the drug delivery system and tissue engineering.
In this paper, we present an efficient rescaling scheme for computing the long-time dynamics of expanding interfaces. The idea is to design an adaptive time-space mapping such that in the new time scale, the interfaces evolves logarithmically fast at early growth stage and exponentially fast at later times. The new spatial scale guarantees the conservation of the area/volume enclosed by the interface. Compared with the original rescaling method in [J. Comput. Phys. 225(1) (2007) 554–567], this adaptive scheme dramatically improves the slow evolution at early times when the size of the interface is small. Our results show that the original three-week computation in [J. Comput. Phys. 225(1) (2007) 554–567] can be reproduced in about one day using the adaptive scheme. We then present the largest and most complicated Hele-Shaw simulation up to date.
The quench sensitivity of 45vol% SiCp/2024Al composites manufactured by squeezed casting method has been investigated by employing Jominy end quench test which was designed to simulate the one dimension cooling process of the composites. It can be found that the cooling rates decreased with the increase of the distance from the quenched end. The results indicated that the as-quenched and as-aged hardness exhibited a significant decrease with increasing the distance from the quenched end. The depths corresponding to 90% of maximum as-aged hardness were 30 mm. When the quench cooling rate was 23.5 °C/s, the hardness was the maximum. The variation of as-aged hardness with cooling rate was identical with the overall enthalpy involved in the precipitation of all metastable phases (S″ + θ″ + S′ + θ′). The SiCp/2024Al composites exhibited two sensitivity regimes: at slower cooling rates the quench sensitivity had been attributed to the formation of intermediate precipitates during cooling, while it was mildly quench sensitive at higher cooling rates.
The dislocation movements under the action of electric pulses (athermal effect) at cryogenic conditions were studied by ex situ transmission electron microscopy (TEM) observations and slip trace analysis innovatively. By applying electric pulses directly through aluminum TEM samples in a liquid nitrogen bath, plenty of non-octahedral-like dislocation glides generally forming at high temperatures (e.g., >453 K for aluminum) were observed at cryogenic temperatures (<130 K). Occurrence of the non-octahedral-like dislocation glides indicates a substantial increase in the degrees of freedom for dislocation glides, offering a new/complementary explanation for the acceleration effect of electric pulses on dislocation movements, especially in the sole athermal effect. In comparison, previous theories relied on extra driving force and/or increased dislocation mobility on the octahedral planes in a face-centered cubic metal. The athermal effects of electric pulse were discussed and the selective heating at the dislocation cores was proposed to account for non-octahedral-like dislocation glides.
In the present work, the effect of pre-ageing temperature and time variations on the mechanical properties and electrical conductivity of the Retrogression and re-aging (RRA) treated 7050 has been investigated. The results reveal that the electronic conductivity and hardness of RRA-treated samples are sensitive to the pre-ageing tempers. The RRA-treated samples with 120 °C/2 h pre-ageing +180 °C/2 h retrogression +120 °C/24 h re-ageing temper can be tailored toward a good combination of strength and elongation, while the electrical conductivity of re-ageing samples is also higher than that of 120 °C/24 h pre-ageing RRA-treated samples. With an intermediate pre-ageing temperature of 80 °C/24 h RRA-treated samples possess a higher re-aged electronic conductivity, while no significant differences can be found between hardness of 120 °C/2 h and 120 °C/24 h pre-ageing RRA-treated samples. The variation of hardness and electronic conductivity during retrogression depends on the pre-ageing tempers. For under-aged sample, the retrogression hardness appears a stage of hardness increasing followed by a further decrease in hardness results, owing to disappearance of dissolving stage of fine GP zone and η′ phase during pre-ageing.
To investigate the effect of different feeding patterns on the occurrence of diseases among infants.
Data on socio-economic status, feeding patterns before 6 months (exclusive breast-feeding (EBF); mixed feeding with breast milk and formula (MBF); exclusive formula-feeding (EFF)) and illness of infants were collected via face-to-face interviews. The proportions of infants who had ever been ill or hospitalized and their potential influence factors were investigated.
Eight large cities in China.
Infants (n 1654) aged 0–11·9 months were recruited from hospitals.
For infants aged 0–2·9 months, the percentage who had been ill was 19·2 %, 24·1 % and 26·3 % among the EBF, MBF and EFF groups, respectively. For those aged 3–5·9 and 6–11·9 months, the corresponding percentages were 41·6 %, 45·6 % and 51·0 %, and 67·0 %, 73·4 % and 67·7 %. Respiratory disease was the most common reported illness and cause of hospitalization. The risks of having (total) illness, diarrhoea and respiratory disease increased significantly with age, but not allergic disease. Compared with EBF, MBF and EFF infants had significantly higher risks of having illnesses except for allergic disease, and feeding patterns were not related to hospitalization. Low birth weight, middle family income and low level of mother’s education also increased the risk of illness.
A protective effect of EBF against total illness in urban Chinese infants was found. An increasing trend with age was observed among the percentages of infants who had been ill or had diarrhoea or respiratory disease, but not allergic disease.
The Chinese black honey bee is a distinct honey bee subspecies distributed in the Xinjiang, Heilongjiang and Jilin Provinces of China. We conducted a study to investigate the genetic origin and the parasite/pathogen profile on Chinese black honeybees. The phylogenetic analysis indicated that Chinese black honeybees were two distinct groups: one group of bees formed a distinct clade that was most similar to Apis mellifera mellifera and the other group was a hybrid of the subspecies, Apis mellifera carnica, Apis mellifera anatolica and Apis mellifera caucasica. This suggests that the beekeeping practices might have promoted gene flow between different subspecies. Screening for pathogens and parasites showed that Varroa destructor and viruses were detected at low prevalence in Chinese black honeybees, compared with Italian bees. Further, a population of pure breeding black honeybees, A. m. mellifera, displayed a high degree of resistance to Varroa. No Varroa mites or Deformed wing virus could be detected in any examined bee colonies. This finding suggests that a population of pure breeding Chinese black honeybees possess some natural resistance to Varroa and indicated the need or importance for the conservation of the black honeybees in China.
Hydroxytyrosol (HT) is a major polyphenolic compound found in olive oil with reported anti-cancer and anti-inflammatory activities. However, the neuroprotective effect of HT on type 2 diabetes remains unknown. In the present study, db/db mice and SH-SY-5Y neuroblastoma cells were used to evaluate the neuroprotective effects of HT. After 8 weeks of HT administration at doses of 10 and 50 mg/kg, expression levels of the mitochondrial respiratory chain complexes I/II/IV and the activity of complex I were significantly elevated in the brain of db/db mice. Likewise, targets of the antioxidative transcription factor nuclear factor erythroid 2 related factor 2 including p62 (sequestosome-1), haeme oxygenase 1 (HO-1), and superoxide dismutases 1 and 2 increased, and protein oxidation significantly decreased. HT treatment was also found to activate AMP-activated protein kinase (AMPK), sirtuin 1 and PPARγ coactivator-1α, which constitute an energy-sensing protein network known to regulate mitochondrial function and oxidative stress responses. Meanwhile, neuronal survival indicated by neuron marker expression levels including activity-regulated cytoskeleton-associated protein, N-methyl-d-aspartate receptor and nerve growth factor was significantly improved by HT administration. Additionally, in a high glucose-induced neuronal cell damage model, HT effectively increased mitochondrial complex IV and HO-1 expression through activating AMPK pathway, followed by the prevention of high glucose-induced production of reactive oxygen species and declines of cell viability and VO2 capacity. Our observations suggest that HT improves mitochondrial function and reduces oxidative stress potentially through activation of the AMPK pathway in the brain of db/db mice.
The Chinese Area Positioning System (CAPS) is a regional satellite navigation system; its space segment consists of some Geostationary Earth Orbit (GEO) satellites and 2∼3 Inclined Geo-Synchronous Orbit (IGSO) satellites. Only a few satellites are needed to provide good area coverage and hence it is an ideal space segment for a regional navigation system. A time transfer mode is used to transmit navigation signals, so no high-precision atomic clocks are required onboard the satellites; all of the transferred navigation signals are generated by the same atomic clock at the master control station on the ground. By using virtual clock technology, the time of emission of signals from the ground control station is transformed to the time of transfer of signals at the phase centre of the satellite antenna; thus the impact of ephemeris errors of satellite on positioning accuracy is greatly decreased, enabling the CAPS to have the capability of wide area augmentation. A novel technology of orbit determination, called Paired Observation Combination for Both Stations (POCBS), proposed by the National Time Service Centre, is used in CAPS. The generation and measurement of ranging signals for the orbit survey are carried out in the ground station and the instrument errors are corrected in real-time. The determination of the clock offset is completely independent of the determination of satellite orbit, so the error of the clock offset has no impact on orbit determination. Therefore, a very high precision of satellite orbits, better than 4·2 cm (1 drms) can be obtained by the stations under regional distribution.
Bifunctional electrocatalytic films were prepared employing a layer-by-layer assembly approach. The cation, metalloporphyrin (MP), and the anion, potassium tetrachloroaurate (KAuCl4) were alternatively assembled on glass or indium-doped tin oxide (ITO) supports. The assembled AuCl4- ions were then converted to gold nanoparticles (Aun) under the exposure to ultraviolet light. Film growth at each adsorption step was monitored by UV-Vis absorption spectroscopy and cyclic voltammetry (CV). The formation of gold nanoparticles was characterized by UV-Vis absorption spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM). Bifunctional electrocatalytic activity of the film was demonstrated in the oxidative detection of nitric oxide (NO) over Aun and the reductive detection of oxygen (O2) over Co(II)P in the same CV scan.
Four kinds of YBa2Cu2Ox (YBCO) superconducting powders with different particle sizes, shapes and different amounts of twins have been prepared in this work. The density, grain sizes, XRD of phase composition, configuration of twins of the ceramics have been investigated. The relation between the characteristics of YBCO powders and the microstructure, current density of the bulk materials are also discussed. In contrast to the YBCO powder prepared by solid state method, the YBCO powders through the improved coprecipitat ion approach have less impurities, smaller particle size and much more amounts of twins, as well as the sintered pellets show a higher density, an orthorhombic single phase, and moreover, the pellets have finer grain boundaries and well developed twins. As a result these samples exhibit current densities (about 1500 A/cm2) higher than those prepared by solid state method. Using BaOx instead of BaCO3 as the starting material, a more dense bulk YBCO ceramics with orthorhombic single phase and Jc (about 1,000 A/cm2) can have also been fabricated by solid state mat hod.
For low-temperature firing of Pb0.94Sr0.06(Ni1/2W1/2)0.02(Mn1/3Nb2/3)0.07(Zr0.51Ti0.49)0.91O3 (PNW–PMN–PZT) system, BiFeO3 is selected as the sintering agent. In this study, the effects of BiFeO3 addition and sintering temperature on the microstructures and piezoelectric properties of the ceramics were investigated in detail. The ceramic with 10 mol% BiFeO3 sintered at 950 °C possesses optimal microstructure and piezoelectric properties. However, with the increase of sintering temperature the lower relative density, abnormal grain growth, and secondary phase accumulated at grain boundaries are observed, which deteriorates the piezoelectric properties. For the ceramics with different BiFeO3 addition sintered at 950 °C, the densification process and the grain growth are improved by suitable BiFeO3, while the morphotropic phase boundary (MPB) moving to the Ti-rich direction and the shrinkage of crystal cell occur. However, extra BiFeO3 inhabits the grain growth and introduces more cavities into the materials. Because of the microstructural changes that accompany the addition of BiFeO3 and the resulting decrease in sintering temperature, the maximum values of the piezoelectric properties are attained. By doping with 10 mol% BiFeO3, the sintering temperature of the PNW–PMN–PZT system can be lowered successfully from 1200 to 950 °C, while the excellent electric properties are kept.
To assess the feasibility of a quarterly antibiotic cycling program at two community hospitals and to evaluate its safety and impact on antibiotic use, expenditures, and resistance.
Nonrandomized, longitudinal cohort study.
Two community hospitals, one teaching and one non-teaching.
Adult medical and surgical inpatients requiring empiric antibiotic therapy.
We developed and implemented a treatment protocol for the empiric therapy of common infections. Between July 2000 and June 2002, antibiotics were cycled quarterly; quinolones, beta-lactam–inhibitor combinations, and cephalosporins were used. Protocol adherence, adverse drug events, nosocomial infections, antibiotic use and expenditures, resistance among clinical isolates, and length of stay were assessed during eight quarters.
Physicians adhered to the protocol for more than 96% of 2,494 eligible patients. No increases in nosocomial infections or adverse drug events were attributed to the cycling protocol. Antibiotic acquisition costs increased 31%; there was a 14.7% increase in antibiotic use. Length of stay declined by 1 day. Quarterly variability in the prevalence of vancomycin-resistant enterococci and ceftazidime resistance among combined gram-negative organisms were noted.
Implementation of an antibiotic cycling program is feasible in a community hospital setting. No adverse safety concerns were identified. Antibiotic cycling was more expensive, partly due to an increase in antibiotic use to optimize initial empiric therapy. Quarterly antibiogram patterns suggested that antibiotic cycling may have impacted resistance, although the small number of isolates precluded statistical analysis. Further assessment of this approach is necessary to determine its relationship to antimicrobial resistance.
The degradation of the steppe ecosystem in Xilingol League in the Inner Mongolia Autonomous Region of China could only be reversed if the intensity of use were reduced, but there have been no studies of how this might be achieved. An investigation of the relationship between Xilingol Biosphere Reserve (XBR) and Xilinhot City explored how greater urbanization might aid restoration of degraded steppe. Experimental data indicate that 72% of the lands have been degraded since 1947, and the relationship between Xilinhot City and the XBR has been reciprocal. The XBR can provide materials such as food, water and a healthy environment for Xilinhot City and Baiyinxile Town, and the high pasture pressure can be reduced by urbanization. The cities could host a substantially greater population in a smaller area than at present, which would in turn reduce pressure on the land. Thus, conservation of the XBR, particularly the core zones, could be ensured through an urban model, which could also provide development opportunities for people moving into conurbations.
Consider the sixth Painlevé equation
$\alpha ,\beta ,\gamma$
are complex parameters. We prove the necessary and sufficient conditions for the existence of rational solutions of equation
in term of special relations among the parameters. The number of distinct rational solutions in each case is exactly one or two or infinite. And each of them may be generated by means of transformation group found by Okamoto  and Bäcklund transformations found by Fokas and Yortsos . A list of rational solutions is included in the appendix. For the sake of completeness, we collected all the corresponding results of other five Painlevé equations
below, which have been investigated by many authors –.
The current-voltage (I-V) characteristics and time-dependence photoconductivity of the undoped and B-doped diamond films (DF's) before and after annealing were investigated. The boron and hydrogen concentration in diamond films were measured by means of nuclear reaction analysis (NRA) and the elastic-recoil detection (ERD) technique, respectively. The results show that induced boron atoms and hydrogen atoms affect the electrical and photocoaductive properties of diamond films. During the annealing process, B concentration kept even, but H content decreased. For undoped diamond films, the escaping of H atoms has great effects on the electrical characteristics, but for B-doped samples, this effect decreases with the increase of B concentration.
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