Search

Flowering time of crops is critical for maximizing yield, quality and regional adaptability under target environments. In rice, Heading date 3a (Hd3a) and Rice Flowering Locus T 1 (RFT1) proteins are the key factors of flowering time regulation in the florigen activation complex. However, effects of hd3a and rft1 mutations on the flowering time under long-day conditions are not clear. In this study, we generated single and double mutants of Hd3a and RFT1 in japonica varieties Shen Nong 9816 (SN9816) background, termed hd3a-SNs, rft1-SNs and doub-SNs, by using CRISPR/Cas9 system. The flowering time of hd3a-SN mutants was similar to wild-type (WT); but mutations of RFT1 delayed flowering time by 11 to 14 days comparing to WT under nature long day (NLD) conditions. Double mutants of Hd3a and RFT1 (doub-SNs) exhibited an extremely late flowering phenotype, and they did not flower up to 365 days after regeneration under either NLD or short-day conditions. The leaf emergency rate of RFT1 mutants was similar to WT, suggesting that the late flowering phenotype of rft1-SNs was caused by delayed floral transition, but not by retarded growth. The expression of the key floral organ identity genes was significantly decreased in rft1-SN and doub-SN mutants, resulting in late flowering phenotypes. The expression profiles, evolution and haplotypes of Hd3a and RFT1 was also analyzed. Our studies provide insight into the potential utilization of Hd3a and RFT1 gene resources to improving growth period and regional adaptability in rice breeding. [ABSTRACT FROM AUTHOR]

The contact properties of the screw-nut pair play a decisive role in the wear rate and service life of ball screws. The difficulty of the ball contact loads directly detected has resulted in the development of many flexible contact models to predict what happens inside the ball screw during its working process. However, few contact models account for nut flexibility when axial load is applied. This article proposes a screw-nut pair contact model with the flexible screw and nut, which are modeled as elastic beams with axial deformations. The geometric relationship of the centers of the raceways and balls is used to describe the variation of the contact loads with the positions of the balls. Effects of the axial, transverse, and torsional deformations of the screw and nut and the geometric error of balls on centers of the raceways and balls are taken into account in the model. For the dynamic model of the feed system, the screw is considered a continuum rod, while the worktable and bearings are treated as lamped masses. The effect of the contact stiffness of the screw-nut pair on the axial and torsional vibration modes of the screw is investigated using a numerical simulation. Moreover, the influences of the worktable position on vibration modes of the feed systems are discussed for the screw with fixed-free and fixed–fixed support modes, respectively. The load-deformation and dynamic experiments are conducted to verify the effectiveness of the proposed models. [ABSTRACT FROM AUTHOR]

As an important atmospheric circulation system in the mid–high latitudes of East Asia, the Northeast China cold vortex (NCCV) substantially influences weather and climate in this region. So far, systematic assessment on the performance of numerical prediction of the NCCVs has not been carried out. Based on the Beijing Climate Centre (BCC) and the ECMWF model hindcast and forecast data that participated in the Sub-seasonal to Seasonal (S2S) Prediction Project, this study systematically examines the performance of both models in simulating and forecasting the NCCVs at the sub-seasonal timescale. The results demonstrate that the two models can effectively capture the seasonal variations in the intensity, active days, and spatial distribution of NCCVs; however, the duration of NCCVs is shorter and the intensity is weaker in the models than in the observations. Diagnostic analysis shows that the differences in the intensity and location of the East Asian subtropical westerly jet and the wave train pattern from North Atlantic to East Asia may be responsible for the deficient simulation of NCCV events in the S2S models. Nonetheless, in the deterministic forecasts, BCC and ECMWF provide skillful prediction on the anomalous numbers of NCCV days and intensity at a lead time of 4–5 (5–6) pentads, and the skill limit of the ensemble mean is 1–2 pentads longer than that of individual members. In the probabilistic forecasts of daily NCCV activities, BCC and ECMWF exhibit a forecasting skill of approximately 7 and 11 days, respectively; both models show seasonal dependency in the simulation performance and forecast skills of NCCV events, with better performance in winter than in summer. The results from this study provide helpful references for further improvement of the S2S prediction of NCCVs. [ABSTRACT FROM AUTHOR]

Rivet connection is one of the most important connection technologies. The main factors affecting the rivet-forming quality of riveted structures are squeezing force, squeezing velocity, and materials of rivets and plates, which significantly impact the damage and failure of riveted holes in riveted structures. This paper provides a detailed study of the rivet-forming quality of riveted structures under different dynamic loads. A theoretical analysis method for the nonlinear dynamic plastic behavior of riveted structures is proposed to predict and investigate the rivet-forming quality of riveted structures under different squeezing forces, velocities, and materials. The proposed theoretical analysis method for the rivet-forming quality of riveted structures is conducted using the explicit dynamics method. Furthermore, the nonlinear dynamic plasticity theory method and nonlinear explicit dynamics model calculation results of riveted structures are compared with measured and Ultra Plus field scanning electron microscope scanning values. The results confirm the accuracy of the nonlinear dynamic plasticity theory method for riveted structures. In addition, the effects of different squeezing forces, velocities, rivet material, and plate material properties on the rivet-forming quality of riveted structures are also studied. This paper proposes a theoretical analysis method for the rivet-forming quality of riveted structures, providing an optimal squeezing force and velocity for rivet hole damage and rivet failure under different rivet and plate materials. [ABSTRACT FROM AUTHOR]

The internal hydrodynamic parameters of extrusion liquefier and bonding neck have an important influence on the forming quality of material extrusion additive manufacturing (MEAM) products. To investigate the relationship, theoretical research and experimental analysis are carried out on both the melt flow behavior (MFB) of the molten polylactic acid (PLA) inside the extrusion liquefier and the bonding neck. They are theoretically modelled based on Newton's power law equation and the viscous sintering phenomenon of the extrudate, respectively. The measurement on the melt pressure drop is then performed with a self-made equipment, and the bonding neck of the sample is observed and measured by scanning electron microscope (SEM). Through the comparison between the predicted and measured results, the proposed theoretical models are validated, and they can give reliable predictions in terms of MFB and bonding neck. The results also show that increasing the extrusion temperature and width will reduce the hydrodynamic parameters (pressure drop, shear stress and apparent viscosity), and increase the bonding neck size of the sample, and thereby improve the forming quality of MEAM products. While for the printing speed, the situation is to the contrary. [ABSTRACT FROM AUTHOR]

As an important component of high-end machine tools, the static and dynamic characteristics of the linear guideway directly affect the machining accuracy of the machine tools. However, most existing literature ignores the effect of the carriage flexibility on the static and dynamic characteristics of the linear guideway. Therefore, this paper proposed a five degree-of-freedom nonlinear dynamic model of the linear guideway considering the carriage flexibility, based on which the static and dynamic characteristics for the linear guideway can be obtained. Firstly, according to the coordinate transformation, the position of the groove centers when the carriage is a rigid body is determined. Next, the FE simulation is used to obtain the relation between the contact load and the carriage flexible deformation. Then, the final position of the groove centers considering the carriage flexibility is calculated, and a five degree-of-freedom nonlinear dynamic model of the linear guideway is established. Finally, the Newmark–Newton numerical algorithm is proposed to solve the nonlinear dynamic equation, and the proposed model is validated through experiments. Furthermore, the static and dynamic characteristics of the linear guideway under the effect of the carriage's rigidity and flexibility are discussed comparatively. [ABSTRACT FROM AUTHOR]

In the process of coal mining, the residual goaf will destroy the stress balance state of the overlying strata, which will result in a large number of fractures. The development of overburden fractures not only affects the movement of strata and the subsidence of surface, but also determines the dominant channel of gas, groundwater and other fluid migration. Therefore, this paper uses 3DEC software to simulate the temporal and spatial evolution of fractures in overlying strata during the mining of coal seam #15 in Pingshu Coal Mine, Qinshui Coalfield, and studies the fractal characteristics of mining overburden fissure development, then we use the drilling hole backwater method to verify the development height of mining-induced fractures. The results show that the overlying strata bend and collapse obviously with the advance of the working face. The development of overburden fractures shows very regular fractal characteristics, and the fractal dimension can be divided into four stages in time and two stages in space. The research results have guiding significance for mastering the law of overburden movement, accurately identifying groundwater and gas enrichment areas, and strengthening the prevention and control of mine water hazards and the effect of gas drainage. [ABSTRACT FROM AUTHOR]

Salt-sensitivity hypertension (SSHTN) is an independent predictor for cardiovascular mortality. VEGFC has been reported to be a protective role in SSHTN and hypertensive kidney injury. However, the underlying mechanisms remain largely unclear. The current study aimed to explore the protective effects and mechanisms of VEGFC against SSHTN and hypertensive nephropathy. Here, we reported that VEGFC attenuated high blood pressure as well as protected against renal inflammation and fibrosis in SSHTN mice. Moreover, VEGFC suppressed the activation of renal NLRP3 inflammasome in SSHTN mice. In vitro, we found VEGFC inhibited NLRP3 inflammasome activation, meanwhile, upregulated autophagy in high-salt-induced macrophages, while these effects were reversed by an autophagy inhibitor 3MA. Furthermore, in vivo, 3MA pretreatment weakened the protective effects of VEGFC on SSHTN and hypertensive nephropathy. Mechanistically, VEGF receptor 3 (VEGFR3) kinase domain activated AMPK by promoting the phosphorylation at Thr183 via binding to AMPK, thus enhancing autophagy activity in the context of high-salt-induced macrophages. These findings indicated that VEGFC inhibited NLRP3 inflammasome activation by promoting VEGFR3-AMPK-dependent autophagy pathway in high-salt-induced macrophages, which provided a mechanistic basis for the therapeutic target in SSHTN and hypertensive kidney injury. [ABSTRACT FROM AUTHOR]

Nanomedicine has become an important development direction of modern medicine, and provides a new way for cancer theranostics. To extend the superior physicochemical property of nanomedicine and enhance their role in cancer theranostics, various strategies have been proposed. Among them, the introduction of oxygen vacancies can enhance the separation of electron-hole pairs and improve the nanomaterials' catalytic activity, which is beneficial for cancer diagnosis and treatment. This review briefly summarized the formation mechanism and preparation methods of various oxygen vacancy nanomaterials. Then, the effect and application of various oxygen vacancy nanomaterials, such as iron, manganese, titanium, zinc, bismuth, tungsten, cerium, and molybdenum-based nanomaterials in enhancing cancer theranostics were highlighted. At last, the prospect and challenges of oxygen vacancy nanomaterials were discussed. This review provided an overview of the relevant information on oxygen vacancy in cancer theranostics, and further promoted the development of cancer nanomedicine. [ABSTRACT FROM AUTHOR]

There exists interrelationship between attributes for multi-attribute group decision making (MAGDM) problems, so capturing correlation among the attributes is necessary. Hence, firstly, the q-rung orthopair fuzzy bi-direction Choquet integral average (q-ROFBDCIA) operator and the q-rung orthopair fuzzy bi-direction exponent Choquet integral geometric (q-ROFBDECIG) operator are introduced to solve decision-making problems (DMPs). These two operators not only define the weight of the attributes but also can depict the relationship between the attributes. Next, the properties and special cases of q-ROFBDCIA and q-ROFBDECIG are shown in detail. And maximizing deviation models to determine fuzzy measure (FM) of decision makers (DMs) and attributes are introduced. Finally, a MAGDM method is established to choose the optical alternative from several alternatives based on the introduced operators and an extended TOPSIS method. A real example is solved by the proposed MAGDM method to exemplify the practicality of the introduced methodology and analyze the superiority of established approach by comparison with other approaches. [ABSTRACT FROM AUTHOR]

The giant thermopower of ionic thermoelectric materials has attracted great attention for waste-heat recovery technologies. However, generating cyclic power by ionic thermoelectric modules remains challenging, since the ions cannot travel across the electrode interface. Here, we reported a reversible bipolar thermopower (+20.2 mV K−1 to −10.2 mV K−1) of the same composite by manipulating the interactions of ions and electrodes. Meanwhile, a promising ionic thermoelectric generator was proposed to achieve cyclic power generation under a constant heat course only by switching the external electrodes that can effectively realize the alternating dominated thermodiffusion of cations and anions. It eliminates the necessity to change the thermal contact between material and heat, nor does it require re-establish the temperature differences, which can favor improving the efficiency of the ionic thermoelectrics. Furthermore, the developed micro-thermal sensors demonstrated high sensitivity and responsivity in light detecting, presenting innovative impacts on exploring next-generation ionic thermoelectric devices. Generating continuous power by ionic thermoelectric material modules remains challenging. Here, the authors find the ionic thermoelectric material exhibiting bipolar thermopower property by manipulating the interactions between ions and electrodes. [ABSTRACT FROM AUTHOR]

Copyright of Advances in Atmospheric Sciences is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Multi-view clustering (MVC) can integrate the complementary information between different views to remarkably improve clustering performance. However, the existing methods suffer from the following drawbacks: (1) multi-view data are often lying on high-dimensional space and inevitably corrupted by noise and even outliers, which poses challenges for fully exploiting the intrinsic structure of views; (2) the non-convex objective functions prone to becoming stuck into bad local minima; and (3) the high-order structure information has been largely ignored, resulting in suboptimal solution. To alleviate these problems, this paper proposes a novel method, namely Self-paced Latent Embedding Space Learning (SLESL). Specifically, the views are projected into a latent embedding space to dimensional-reduce and clean the data, from simplicity to complexity in a self-paced manner. Meanwhile, multiple candidate graphs are learned in the latent space by using embedded self-expressiveness learning. After that, these graphs are stacked into a tensor to exploit the high-order structure information of views, such that a refined consensus affinity graph can be obtained for spectral clustering. The experimental results demonstrate the effectiveness of our proposed method. [ABSTRACT FROM AUTHOR]

Single nucleotide polymorphisms (SNPs) in metagenomics are used to quantify population structure, track strains and identify genetic determinants of microbial phenotypes. However, existing alignment-based approaches for metagenomic SNP detection require high-performance computing and enough read coverage to distinguish SNPs from sequencing errors. To address these issues, we developed the GenoTyper for Prokaryotes (GT-Pro), a suite of methods to catalog SNPs from genomes and use unique k-mers to rapidly genotype these SNPs from metagenomes. Compared to methods that use read alignment, GT-Pro is more accurate and two orders of magnitude faster. Using high-quality genomes, we constructed a catalog of 104 million SNPs in 909 human gut species and used unique k-mers targeting this catalog to characterize the global population structure of gut microbes from 7,459 samples. GT-Pro enables fast and memory-efficient metagenotyping of millions of SNPs on a personal computer. Alignment-free SNP calling from metagenomes reduces computational time by two orders of magnitude. [ABSTRACT FROM AUTHOR]

The contact state and stiffness of linear guide are affected by the complex external loads, and the vibrations in different directions are coupled with each other. However, existing dynamic models are inaccurate because they ignore displacement coupling and do not consider the position deviation of guide rail. This paper presents a five degree-of-freedom dynamic model for table system that incorporates the effects of the displacement coupling and position deviation of guide rail. The ball-to-groove contact model and position deviation model are established by using the Hertz contact theory and homogeneous coordinate transformation, respectively. Dynamic equations are solved by combining the Monte Carlo and Newmark methods to determine the displacements of table system, and the accuracy of proposed dynamic model is verified through experimental method. The results show that the vibrations of table system are coupled with each other, and the position deviation of guide rail only affects the vibration amplitudes in the region other than the resonance regions. Proposed model is thus suitable for improving the machining accuracy and stability of machine tools. [ABSTRACT FROM AUTHOR]

Copyright of Advances in Atmospheric Sciences is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The understanding of centennial trends of extreme temperature has been impeded due to the lack of early-year observations. In this paper, we collect and digitize the daily temperature data set of Northeast China Yingkou meteorological station since 1904. After quality control and homogenization, we analyze the changes of mean and extreme temperature in the past 114 years. The results show that mean temperature (Tmean), maximum temperature (Tmax), and minimum temperature (Tmin) all have increasing trends during 1904–2017. The increase of Tmin is the most obvious with the rate of 0.34 °C/decade. The most significant warming occurs in spring and winter with the rate of Tmean reaching 0.32 °C/decade and 0.31 °C/decade, respectively. Most of the extreme temperature indices as defined using absolute and relative thresholds of Tmax and Tmin also show significant changes, with cold events witnessing a more significant downward trend. The change is similar to that reported for global land and China for the past six decades. It is also found that the extreme highest temperature (1958) and lowest temperature (1920) records all occurred in the first half of the whole period, and the change of extreme temperature indices before 1950 is different from that of the recent decades, in particular for diurnal temperature range (DTR), which shows an opposite trend in the two time periods. [ABSTRACT FROM AUTHOR]

Based on the ground surface temperature (GST) and snow surface temperature (SST) measurements during the period of adjustment from manual to automatic observation systems in China, the influence of observation methods on GST and its relationship with snow cover is analyzed. GST is corrected by SST, and the correction effect is evaluated. The results show that, during the parallel observation period, the winter GSTs from automatic observations are generally higher than those from manual observations, with the automatically observed national daily GST 1.18°C higher. The adjustment has a greater impact on GSTs at 0200, 0800, and 2000 Beijing Time (BT) than at 1400 BT, and it has the greatest impact in Northeast and Northwest China, with deviations of 5.24 and 2.09°C, respectively. The GST deviation is closely related to the snow depth and annual snow totals. The average daily GST deviation increases at the rate of 0.66°C per 1-cm increase of snow depth when it is < 15 cm, while it tends to be stable at around 10°C for snow depth over 15 cm. The GST deviation at a station is affected by its winter snow totals in Northeast and Northwest China, where the largest deviations are found where snow totals are all above 1000 cm. After the correction with SST, the mean deviation between the automatic and manual observations as well as the false trend can be effectively reduced. Following the correction, the mean deviation of daily GST decreases by 5.8°C, and its trend decreases from 1.87 to 0.65°C decade−1. [ABSTRACT FROM AUTHOR]

The gut of healthy human neonates is usually devoid of viruses at birth, but quickly becomes colonized, which—in some cases—leads to gastrointestinal disorders1–4. Here we show that the assembly of the viral community in neonates takes place in distinct steps. Fluorescent staining of virus-like particles purified from infant meconium or early stool samples shows few or no particles, but by one month of life particle numbers increase to 109 per gram, and these numbers seem to persist throughout life5–7. We investigated the origin of these viral populations using shotgun metagenomic sequencing of virus-enriched preparations and whole microbial communities, followed by targeted microbiological analyses. Results indicate that, early after birth, pioneer bacteria colonize the infant gut and by one month prophages induced from these bacteria provide the predominant population of virus-like particles. By four months of life, identifiable viruses that replicate in human cells become more prominent. Multiple human viruses were more abundant in stool samples from babies who were exclusively fed on formula milk compared with those fed partially or fully on breast milk, paralleling reports that breast milk can be protective against viral infections8–10. Bacteriophage populations also differed depending on whether or not the infant was breastfed. We show that the colonization of the infant gut is stepwise, first mainly by temperate bacteriophages induced from pioneer bacteria, and later by viruses that replicate in human cells; this second phase is modulated by breastfeeding. The infant gut is colonized first by temperate bacteriophages induced from pioneer bacteria and later by viruses that replicate in human cells, the populations of which are modulated by breastfeeding. [ABSTRACT FROM AUTHOR]

Amyloid aggregation of α-synuclein (α-syn) is closely associated with Parkinson's disease (PD) and other synucleinopathies. Several single amino-acid mutations (e.g. E46K) of α-syn have been identified causative to the early onset of familial PD. Here, we report the cryo-EM structure of an α-syn fibril formed by N-terminally acetylated E46K mutant α-syn (Ac-E46K). The fibril structure represents a distinct fold of α-syn, which demonstrates that the E46K mutation breaks the electrostatic interactions in the wild type (WT) α-syn fibril and thus triggers the rearrangement of the overall structure. Furthermore, we show that the Ac-E46K fibril is less resistant to harsh conditions and protease cleavage, and more prone to be fragmented with an enhanced seeding capability than that of the WT fibril. Our work provides a structural view to the severe pathology of the PD familial mutation E46K of α-syn and highlights the importance of electrostatic interactions in defining the fibril polymorphs. The E46K α-synuclein mutation causes familial Parkinson's disease. Here, the authors present the cryo-EM structure of N-terminally acetylated E46K α-synuclein fibrils and find that it is distinct from other known α-synuclein fibril structures. [ABSTRACT FROM AUTHOR]

Aims: Seagrass beds occur globally and are substantial blue carbon sinks, yet factors that affect sediment organic carbon (SOC) sequestration are poorly characterized. We investigated the influences of eutrophication on SOC sequestration capacity in a mixed seagrass bed dominated by Thalassia hemprichii and Enhalus acoroides.Methods: We surveyed a tropical seagrass bed in the South China Sea along fish farming-induced gradients of nutrients to assess the variability of SOC content and composition in 30-cm-long sediment cores.Results: No significant difference was observed for the SOC content and stock between the two species. Significantly higher microbial biomass carbon and SOC density were observed at the surface 3 cm layer under E. acoroides, and the longer roots of E. acoroides enhanced the seagrass contribution to the SOC near the root tip. SOC had a statistically lower concentration in the sediment layers where the seagrass roots primarily thrive close to fish farming, but greater exchangeable organic carbon was found in all the sediment layers as they approached fish farming. Nutrient enrichment markedly induced a larger ratio of labile C pools in almost all sediment layers. The mean SOC stock in the seagrass bed in Xincun Bay was 6.80 ± 1.03 Mg C/ha, and it showed insignificant variation along the nutrient gradient.Conclusions: Eutrophication may indirectly reduce the SOC sequestration capacity in the seagrass bed by enhancing labile organic carbon with a shorter resident time, and measures should be taken to reduce nutrient input into the seagrass bed to enhance its carbon sink. [ABSTRACT FROM AUTHOR]

Streptococcusthermophilus is one of the economically most representatives of lactic acid bacteria, which is widely used as a starter to produce fermented milk products. In this study, 22 S. thermophilus strains were isolated from 26 fermented milk samples. Most isolates showed the ability to ferment a broad range of carbohydrates. Interestingly, eight strains are galactose positive, which is a desirable property in various industrial dairy fermentations. Four different nucleotide sequences were found in the galR-galK intergenic regions. The 16S-23S intergenic spacer region sequences of most isolates were determined as ITS-St-II type, which are related with protease positive and fast acidification. CS18 presented excellent technological performances, and showed potential as a promising starter candidate. To gain a comprehensive view of stress response mechanisms of strains, the distribution of all the two-component systems (TCSs) in strains were investigated. TCS analysis indicated that the nucleotide sequence of TCSs have obvious differences in different strains. And the strains with the special nucleotide sequences of TCS have distinctive traits. Therefore, it was speculated that there is a certain connection between the traits’ difference and the TCS difference of strains. [ABSTRACT FROM AUTHOR]

Based on summer precipitation hindcasts for 1991-2013 produced by the Beijing Climate Center Climate System Model (BCC_CSM), the relationship between precipitation prediction error in northeastern China (NEC) and global sea surface temperature is analyzed, and dynamic-analogue prediction is carried out to improve the summer precipitation prediction skill of BCC_CSM, through taking care of model historical analogue prediction error in the real-time output. Seven correction schemes such as the systematic bias correction, pure statistical correction, dynamic-analogue correction, and so on, are designed and compared. Independent hindcast results show that the 5-yr average anomaly correlation coefficient (ACC) of summer precipitation is respectively improved from -0.13/0.15 to 0.16/0.24 for 2009-13/1991-95 when using the equally weighted dynamic-analogue correction in the BCC_CSM prediction, which takes the arithmetical mean of the correction based on regional average error and that on grid point error. In addition, probabilistic prediction using the results from the multiple correction schemes is also performed and it leads to further improved 5-yr average prediction accuracy. [ABSTRACT FROM AUTHOR]

Seagrass leaf litters are an important source of sediment organic carbon (SOC). However, the mechanisms of seagrass leaf litter decomposition influencing SOC composition and the key transformation processes remain unknown. We performed a laboratory chamber experiment to compare the labile organic carbon (OC) composition and the enzyme activities governing SOC transformation between the seagrass group (seagrass leaf litter addition) and the control group. The results showed that the seagrass leaf litter decomposition significantly elevated the salt-extractable carbon (SEC) content and the SEC/SOC. Additionally, the levels of invertase, polyphenol oxidase, and cellulase in the seagrass leaf litters addition group were generally higher than in the control group, which could elevate recalcitrant OC decomposition. Following 24 days incubation, addition of seagrass leaf litter increased the amount of CO2 released, but decreased the SOC content. Therefore, seagrass leaf litter decomposition leached abundant dissolved OC, which enhanced the activity and transformation of SOC. [ABSTRACT FROM AUTHOR]

This paper presents an experimental investigation of the performance of a system combining a low-temperature water wall radiant heating system and phase change energy storage technology with an active solar system. This system uses a thermal storage wall that is designed with multilayer thermal storage plates. The heat storage material is expanded graphite that absorbs a mixture of capric acid and lauric acid. An experiment is performed to study the actual effect. The following are studied under winter conditions: (1) the temperature of the radiation wall surface, (2) the melting status of the thermal storage material in the internal plate, (3) the density of the heat flux, and (4) the temperature distribution of the indoor space. The results reveal that the room temperature is controlled between 16 and 20 °C, and the thermal storage wall meets the heating and temperature requirements. The following are also studied under summer conditions: (1) the internal relationship between the indoor temperature distribution and the heat transfer within the regenerative plates during the day and (2) the relationship between the outlet air temperature and inlet air temperature in the thermal storage wall in cooling mode at night. The results indicate that the indoor temperature is approximately 27 °C, which satisfies the summer air-conditioning requirements. [ABSTRACT FROM AUTHOR]

A consecutive centrifugal method was developed to concentrate enteric viruses from water. Using five selected human enteric viruses, the recovery rates were evaluated and compared with results from NanoCeram filtration methods. The highest recovery rate was achieved for coxsackievirus (78.11 %, 42.97-101.39), and the lowest rate was for adenovirus (32.84 %, 19.68-66.20). In comparison with NanoCeram disc filtration with beef-extract flocculation (BE), the recovery rate was increased for all viruses. The rate of increase varied from a low of 8.24 % (astroviruses) to a high of 24.22 % (noroviruses). The NanoCeram filtration with BE was further modified by NaPP buffer plus one-step centrifugation using a Centricon plus-70 device. The modified method further increased the concentrations of viruses in the sample. Virus concentration was increased to 19.45 ± 7.19-fold for rotavirus, 19.40 ± 6.54-fold for norovirus, 16.10 ± 7.61-fold for coxsackievirus, 12.80 ± 3.00-fold for astrovirus and 11.97 ± 6.94-fold for adenovirus compared to the NanoCeram filtration with BE. Subsequent cell culture showed that the infectivity of the viruses was not altered by any of the three methods. Three methods will provide testing labs with choices for cost-effective approaches to concentrate viruses from water. [ABSTRACT FROM AUTHOR]

This paper aims at studying theoretically synchronization of two exciters in a nonlinear vibrating system (NVS), in which the behavior of NVS is mainly reflected at nonlinear restoring forces of springs with piecewise linear characters. The differential motion equations of two rigid frames in the horizontal direction are combined into their relative motion equation. Based on the asymptotic method, the nonlinear stiffness of springs is linearized equivalently as a function of the amplitude of the relative motion. Using Lagrange's equations, the differential motion equations of the total system are deduced. The criterion of synchronization for two exciters in the analytical form is derived, by the average method. According to the principle that the stable solution of the synchronous states corresponds to a minimum point of Hamilton's average action amplitude of the system, the criterion of stability of the synchronous states is achieved analytically. States of the system versus the operating frequency under consideration of multiple resonant types are presented. For the synchronous vibrating machines with two rigid frames used in engineering, the condition of the minimum of excitation to foundation is discussed, as well as the ideal working regions of the vibrating machines. [ABSTRACT FROM AUTHOR]

The experiment was conducted to investigate the effect of high dietary copper on catecholamine concentration and dopamine-β-hydroxylase (DβH) activity in hypothalami and midbrains of growing pigs. Forty-five crossbred weanling pigs with an average body weight of 7.5 kg were randomly assigned to three groups of 15 each to receive a control diet containing 10 mg/kg Cu (diet A) and diets containing 125 (diet B) or 250 (diet C) mg Cu/kg DM for 45 days. Compared to the control, Cu supplementation at both 125 and 250 mg Cu/kg DM increased average daily gain (ADG), average daily feed intake (ADFI), and feed efficiency. High dietary copper increased midbrain and hypothalami dopamine (DA) and norepinephrine (NE) concentrations and midbrain dopamine-β-hydroxylase activity. However, increasing dietary Cu had no effect on hypothalami dopamine-β-hydroxylase activity. [ABSTRACT FROM AUTHOR]

This paper is a continuation of the previous work by means of numeric and experiment. The coupling characteristics of two exciters are described briefly. Numerical analyses corresponding to the previous theoretical results are given. Here the response curve of the frequency-amplitude reflects distinctly the hardening nonlinear characteristic of the system. The key factors of implementing synchronization and ensuring stability are weighed up by the possibilities of synchronization and stability, respectively. Three types of phase relationships of the system in the steady state are discussed, as well as the load torque of two motors. It is shown that the greater and stable response of the relative motion can be achieved in the sub-resonant or near sub-resonant state, for two identical exciters. In this case the phase difference of two exciters is stabilized in the vicinity of zero, and the relative motion of two rigid frames is the opposite phase. The above facts are exactly the desires in engineering. An experiment is carried out, and several satisfactory experimental results are obtained for different resonant types, which are in approximate or good agreement with the numerical results. By comparison with theory, numeric and experiment, the feasibility and validity of the theory method used are examined and verified. [ABSTRACT FROM AUTHOR]

This paper studies self-synchronization and stability of a dual-motor driven vibration system with a two-stage vibration isolation frame. Oscillation amplitude of the material box large enough can be ensured on the vibration system in order to screen materials. Reduction of the dynamic load transmitted to the foundation can also be achieved for the vibration system. A Lagrange equation is used to set up the motion differential equations of the system, and a dimensionless coupled equation of the eccentric rotors is obtained using a method of modified average small parameter. According to the existence condition of zero solution in the dimensionless coupled equation of the eccentric rotors, the precondition for commencing self-synchronization motion is achieved. The stability condition of self-synchronization is obtained based on the Routh-Hurwitz criterion. The theoretical analysis is validated by simulations and experiments. [ABSTRACT FROM AUTHOR]

In this study, vibratory synchronization transmission (VST) of two exciters is investigated in a super-resonant vibrating system to save energy. First, the frequency capture equation of two exciters (FCETE) is deduced by the average method of small parameters. The criterion of VST being the equivalent effective residual torque of motor with power supply should be smaller or equal to the frequency capture torque of the system by setting the disturbance parameters of angular velocities in FCETE to zero. The stability criterion of synchronous states is derived by complying with the generalized Lyapunov equations. Lastly, experiment and computing simulation on VST are conducted. The VST regime of two exciters is discussed in detail from coupling characteristic, current change, visual picture, phase relation, and direct verification of parameters, respectively by comparison and analyses of corresponding data. Results indicate that the key factor in VST implementation is the torque of frequency capture, which serves as the 'vehicle' in transferring energy. Thus, the distance between rotational centre of each exciter and mass centre of the rigid frame should be far enough to enhance the ability of VST and ensure energy saving. The theory, experiment, and computing simulation prove that the theoretical approach used in this study is useful and feasible. [ABSTRACT FROM AUTHOR]

Metamorphic GaInAs/AlInAs buffers with a total mismatch of 2 % with respect to GaAs have been grown by metal organic chemical vapor deposition on GaAs substrates with miscuts of 2°, 7° and 15° toward (111)A. The buffer grown on 2° miscut substrate exhibits a dislocation pile-up formation which increases the threading dislocation density greatly. However, using 7° and 15° off substrates eliminates the dislocation pile-up and decreases the dislocation density by an order of magnitude compared with that on the 2° substrate miscut, and the best crystalline quality of buffer is obtained on the 15° substrate miscut. Experimental results show that the buffers grown on the 7° and 15° miscut substrate exhibit shallower trenches on the surface and a weaker strain field in the InGaAs cap layers, and these help to suppress the occurrence of dislocation pile-up, leading to a lower threading dislocation density. [ABSTRACT FROM AUTHOR]

A dynamic model of a multi-shaft helical geared rotor system is presented. Rotating shafts of the system are modeled as Timoshenko beams. A general three-dimensional dynamic model of helical gear pairs with geometric eccentricity is developed for the gear mesh and bearing flexibility is included in the model as well. The transmission error and gear geometric eccentricity are simulated as excitations. Eigenvalue solution and the modal summation technique are used to predict the natural frequencies and forced responses of the system. Then two geared rotor system models are presented for validation of the gear dynamic model. It is demonstrated that the gear mesh model is effective for general geared rotor systems, spur and helical gears, one-stage and multi-stage systems. Finally, forced responses of an example system are analyzed to demonstrate the influences of the helical gear geometric eccentricity and the coupling between gear geometric eccentricity and rotor mass unbalance. [ABSTRACT FROM AUTHOR]

Based on 1961-2005 observed winter precipitation data in Northeast China, the temporal and spatial variations of snow concentration degree (SCD) and snow concentration period (SCP), together with the circulation characteristics when there is a higher SCD, are computed and analyzed. Results show that SCD in Northeast China presents a yearly rising tendency and SCP decreases obviously. In terms of decadal variation, there is a 12-year periodic variation in PCP, and since the mid-1970s there has been an 8-year short periodic variation. As to spatial variation, SCD in winter of Northeast China has increased gradually from the eastern part to the western, and the minimum value of SCD occurs in the east of Jilin Province, while the high value center is observed in the central part of the province. For the whole Northeast China, the variation tendencies are consistent in the eastern and central parts, where SCD presents a rising tendency and SCP shows a decreasing tendency. SCD in the southwestern and northern parts has a slight rising tendency, with SCD in the southwestern part having the slightest increasing tendency, and SCP in the northern part showing the slightest decreasing tendency. When a high SCD value is observed, the whole region is controlled by the East Asian deep trough at 500 hPa, and the trough becomes deeper in the western part, while a high pressure, which is easily formed and intensified in the eastern part, makes the East Asian deep trough move eastward slowly. Upper-level jet stream and low-level jet stream co-exist, and the former is stronger and takes more of a southwestward position than the latter. The high value zone of water vapor transport over the Pacific is intensified obviously, and the extent also increases. Northeast China is influenced by the water vapor transported to the northwest along the north of the high value center. [ABSTRACT FROM AUTHOR]

This paper presents a design method for Class-E power amplifiers based on the analysis of the load impedance in the frequency domain. The analytical expressions of the design parameters are derived as functions of the duty ratio D and angular frequency ω of the gate driven voltage of the switch. According to the analysis, for an optimal Class-E amplifier that meets both the zero-voltage switching (ZVS) and the zero-derivative switching (ZDS) conditions, the increase of the duty ratio D results in the decrease of the DC input resistance, and this consequently increases the input power and decreases the total efficiency. Two design procedures for different design purposes are discussed under three cases with different duty ratios, i.e. D = 0.25, 0.5 and 0.75. The simulation and experimental results of these cases agree well with the theoretical ones. [ABSTRACT FROM AUTHOR]

In the average method of modified small parameters, the synchronization of two coupled exciters is converted to a problem on the existence and stability of zero solutions for the average differential equations of small parameters over the average period of two exciters. To implement frequency capture, the torque of frequency capture should be greater than or equal to the absolute value of the difference between the residual electromagnetic torques of the two motors. Because each exciter is involved in the motion of the vibrating system it has excited, its relative moment of inertia is reduced. The reduction is proportional to half its coefficient of cosine effect of phase angles ( CCEPA). Because one of the exciters is involved in the motion excited by the other, a coupled moment of inertia exists for the two exciters. The stability of the synchronization of the two exciters is affected by the reduction of their relative moments of inertia and their moment of coupling inertia. For the synchronization to be stable, two conditions must be satisfied: (1) the non-dimensional relative moments of inertia of the two exciters are all greater than zero, and (2) four times the product of their non-dimensional relative moments is greater than the square of the coefficient of coupled cosine effect ( CCCPA). The stability of synchronization depends solely on the ratios of the masses of the two exciters to the mass of the vibrating system and the ratio of the distance between one exciter and the centroid of the rigid frame to the equivalent rotating radius of the vibrating system about its centroid of the rigid frame, and is independent of the parameters of the two induction motors. [ABSTRACT FROM AUTHOR]

The paper proposes an analytical approach to investigate the synchronization of the two coupled exciters in a vibrating system of spatial motion. Introducing the disturbance parameters for average angular velocity of two exciters, we deduce the non-dimensional coupling equations of angular velocities of two exciters, in which the inertia coupling matrix is symmetric and the stiffness coupling matrix is antisymmetric in a non-resonant vibrating system. The analysis of the coupling dynamic characteristic shows that the coupled cosine effect of the phase angles will cause the torque acting on two motors to limit the increase of phase difference between two exciters as well as sustain its symmetry of two exciters during the running process. It physically explains the peculiarity of self-synchronization of two exciters. The cosine effect of phase angles of the vibrations excited by each exciter will decrease its moment of inertia. The residual moment of inertia of each exciter represents its relative moment of inertia. The stability condition of synchronization of two exciters is that the relative non-dimensional moments of inertia of two exciters are all greater than zero and four times their product is greater than the square of their coefficient of coupled cosine effect of phase angles, which is equivalent to that the inertia coupling matrix is positive definite and all its elements are positive. The numeric results show that the structure of the vibrating system can ensure the stability condition of synchronous operation. [ABSTRACT FROM AUTHOR]

A new mechanism is proposed to implement the synchronization of the four unbalanced rotors in a vibrating system, which consists of a main rigid frame (MRF) and two accessorial rigid frames (ARF). An analytical approach is developed to study the coupling dynamic characteristics of the four unbalanced rotors, which converts the problem of synchronization of the four unbalanced rotors into the existence and the stability of zero solutions for the non-dimensional differential equations of the angular velocity disturbance parameters (NDDEDP). The stability of zero solutions of the NDDEDP is decomposed into that of its generalized system and a system of the three first order differential equations for the disturbance parameters of the phase differences. The coupling dynamic characteristic of the four unbalanced rotors includes the inertia coupling, the stiffness coupling of angular velocity and the load torque coupling. The non-dimensional inertia coupling matrix is symmetric, the non-dimensional matrix of the stiffness coupling of angular velocity is antisymmetric and its diagonal elements are all negative. Hence, the general system of the NDDEDP automatically satisfies the generalized Lyapunov equations when the non-dimensional inertia coupling matrix is positive definite and its elements are all positive. Using Routh-Hurwitz criterion the condition of stability of differential equations for the disturbance parameters of the phase differences is obtained. The load torque coupling makes the vibrating system have the dynamic characteristic of selecting motions and self-synchronization of the four unbalanced rotors arises from the dynamic characteristic of selecting motion of the vibrating system. When the two coefficients of coupling cosine effect of phase angles are all greater than 0 and the three indexes of synchronization are all far greater than 1, the vibrating system can implement an elliptical motion of the main rigid frame required in engineering. Numeric results show that the structural parameters of the proposed mechanism can guarantee the non-dimensional inertia matrix to be always positive definite. Computer simulation is carried out to verify the results of the theoretical investigation. [ABSTRACT FROM AUTHOR]

The dynamic model of a self-synchronous vibrating machine is established. Through the dynamic analysis of the self-synchronous vibrating machine with two motors, the simulation program is run based on the dynamic model of self-synchronous vibrating machine and the mathematical model of an induction motor. Simulation results show that the machine is in a poor synchronous state. The method to control the phase difference of the two eccentric rotors is then analyzed, and the self-synchronous vibrating machine is optimization designed. The simulation demonstrates that the self-synchronous vibration machine achieves speed synchronization and phase synchronization. The results verify the effectiveness of the optimization design. [ABSTRACT FROM AUTHOR]

The spontaneous self-assembly of multicellular ensembles into living materials with synergistic structure and function remains a considerable challenge in biotechnology and synthetic biology. Here, we exploit the aqueous two-phase separation of dextran-in-PEG emulsion micro-droplets for the capture, spatial organization and immobilization of algal cells or algal/bacterial cell communities to produce discrete multicellular spheroids capable of both aerobic (oxygen producing) and hypoxic (hydrogen producing) photosynthesis in daylight under air. We show that localized oxygen depletion results in hydrogen production from the core of the algal microscale reactor, and demonstrate that enhanced levels of hydrogen evolution can be achieved synergistically by spontaneously enclosing the photosynthetic cells within a shell of bacterial cells undergoing aerobic respiration. Our results highlight a promising droplet-based environmentally benign approach to dispersible photosynthetic microbial micro-reactors comprising segregated cellular micro-niches with dual functionality, and provide a step towards photobiological hydrogen production under aerobic conditions. The development of techniques capable of orchestrating the assembly of living cells into multicellular ensembles with synergistic and function is challenge. Here, the authors construct algal or algal/bacterial cells-based core shell-like structure based on aqueous two-phase system for synergic photosynthetic H2 production. [ABSTRACT FROM AUTHOR]