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We report a search for a dark photon using $14.9$~fb$^{-1}$ of $e^+e^-$ annihilation data taken at center-of-mass energies from 4.13 to 4.60~GeV with the BESIII detector operated at the BEPCII storage ring. The dark photon is assumed to be produced in the radiative annihilation process of $e^+e^-$ and to predominantly decay into light dark matter particles, which escape from the detector undetected. The mass range from 1.5 to 2.9~GeV is scanned for the dark photon candidate, and no significant signal is observed. The mass dependent upper limits at the 90$\%$ confidence level on the coupling strength parameter $\epsilon$ for a dark photon coupling with an ordinary photon vary between $1.6\times 10^{-3}$ and $5.7\times10^{-3}$., Comment: 8 pages, 3 figures

To avoid the loss of catalytic material powder, a loaded catalytic material of TiO2 with basalt fiber as the carrier (TiO2@BF) was synthesized by an improved sol–gel method. The TiO2@BF was doped with different contents of N, Fe and Zn elements and was used to degrade rhodamine B (RhB) under ultraviolet light. The physical characterization analysis indicated that the co-doping of the N, Fe and Zn elements had the effects of reducing grain size, increasing sample surface area, and narrowing the electronic band gap. The electronic band gap of nitrogen–iron–zinc co-doped TiO2@BF (N/Fe/Zn_TiO2@BF) was 2.80 eV, which was narrower than that of TiO2@BF (3.11 eV). The degradation efficiency of RhB with N/Fe/Zn_TiO2@BF as a photocatalyst was 4.3 times that of TiO2@BF and its photocatalytic reaction was a first-order kinetic reaction. Quenching experiments suggested that the reactive species mainly include photoinduced holes (h+), superoxide radicals (˙O2−) and hydroxyl radicals (˙OH). In brief, this study provides a prospective loaded catalytic material and routine for the degradation of organic contaminants in water by a photocatalytic process.

To compare the effectiveness and safety of robotic surgery with that of open operations for patients with cancers of the head and neck we made an electronic search of the CENTRAL, MEDLINE, EMBASE, CNKI, CBM, Opengray and Sciencepaper Online databases, and then made a manual search of specific online databases and the reference lists of relevant papers. Our most recent searches were made on 18 July 2018, and we included randomised controlled trials (RCT), case-control studies, cohort studies, and cross-sectional surveys in which robotic was compared with open surgery for cancer of the head and neck. Data from all the studies included were extracted by two independent workers. The risk ratio was chosen to measure dichotomous effects of treatment for prospective studies including RCT or cohort studies, while the odds ratio was chosen for case-control or cross-sectional studies. The weighted mean difference or standard mean difference was chosen to summarise continuous effects. A random-effects model was used for all data analyses. Thirteen studies were included: one RCT, nine cohort studies, and three cross-sectional studies. Robotic surgery was associated with fewer invaded resection margins, lower recurrence, less need for intraoperative tracheostomy, and less need and shorter duration of postoperative nasal feeding than open operations. Robotic surgery is a safe and feasible approach with remarkable superiority over open surgery for the treatment of cancers of the head and neck.

In-situ synthesized titanium borides reinforced Ti-6Al-4V composites with a tailored reinforcement architecture were successfully prepared by hot isostatic pressing (HIP) starting from a TiB2/Ti-6Al-4V powder system. The microstructure of the composite samples was investigated using X-ray diffraction (XRD) technique and scanning electron microscopy (SEM), and the mechanical properties were evaluated through room and high temperature tensile testing. It is found that during HIP the additive particles TiB2 have totally transformed into TiB needles, which tend to decorate at prior particle boundaries of the consolidated powder particles to form a network structure. With increasing TiB2 addition from 3 wt.% to 8 wt.%, the microstructural feature of the TiB network structure experiences the variations of discontinuous TiB reinforcement → quasi-continuous TiB reinforcement → continuous TiB reinforcement. The room temperature tensile properties of the composites are improved with increasing addition of TiB2 from 3 wt.% to 5 wt.%, but the tensile strength of the sample with 8 wt.% TiB2 drastically decreases. As to the high temperature properties, the titanium boride reinforced Ti-6Al-4V alloy composites can be an increased maximum service temperature by over 200 °C while retaining the same tensile strength accompanied with a suitable elongation. The strengthening mechanism is mainly attributed to the load-bearing transformation, grain refinement and dispersion strengthening.

As natural agroecology deteriorates, controlled environment agriculture (CEA) systems become the backup support for coping with future resource consumption and potential food crises. Compared with natural agroecology, most of the environmental parameters of the CEA system rely on manual management. Such a system is dependent and fragile and prone to degradation, which includes harmful bacteria proliferation and productivity decline. Proper water management is significant for constructing a stabilized rhizosphere microenvironment. It has been proved that water is an efficient tool for changing the availability of nutrients, plant physiological processes, and microbial communities within. However, for CEA issues, relevant research is lacking at present. The article reviews the interactive mechanism between water management and rhizosphere microenvironments from the perspectives of physicochemical properties, physiological processes, and microbiology in CEA systems. We presented a synthesis of relevant research on water–root–microbes interplay, which aimed to provide detailed references to the conceptualization, research, diagnosis, and troubleshooting for CEA systems, and attempted to give suggestions for the construction of a high-tech artificial agricultural ecology.

Sichuan, a hilly area in southwestern China, is recommended as a bioethanol production base because of its abundant crop residue resources. However, removing the crop straw for bioethanol may negatively affect soil fertility and productivity due to the local purple soil vulnerability. To explore the impact of crop residue removal on soil fertility and productivity and meet the needs of sustainable agriculture, we conducted a crop residue removal experiment by measuring the soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) contents, and crop yield in the purple soil region in southwest China. Soil erosion was also simulated by Revised Universal Soil Loss Equation version 2 (RUSLE 2). The results showed that soil erosion increased with the increase of the straw removal rate. Compared with 0% removal treatment, the SOC content reduced at other removal rate treatments, especially for long-term residue removal. The effect of residue removal on soil TN and TP was not consistent within one year. After two years, residue removal greater than 25% caused a decrease in TN by 1.6–3.7%, and straw removal greater than 50% caused a TP decrease by 8.5–9.3%. More than 25% of the residue removed reduced maize and canola yields, and TN and TP content. However, all crop residue removal treatments resulted in SOC content reduction and soil erosion deterioration. In conclusion, crop residue removal was not recommended due to agricultural sustainability in Sichuan, China.

As the remote sensing technology develops, there are increasingly more kinds of remote sensing images available from different sensors. High-resolution remote sensing images are widely used in the detection of land cover/land change due to their plenty of characteristics of a specific feature in terms of spectrum, shape, and texture. Current studies regarding cultivated land resources that are the material basis for the human beings to survive and develop focus on the method to accurately obtain the quantity of cultivated land in a region and understand the conditions and the trend of change of the cultivated land. Pixel-based method and object-oriented method are the main methods to extract cultivated land in remote sensing field. Pixel-based method ignores high-level image information, while object-oriented method takes the image spot after image segmentation as the basic unit of information extraction, which can make full use of spectral features, spatial features, semantic features, and contextual features. Image segmentation is a key step of object-oriented method; the core problem is how to obtain the optimal segmentation scale. Traditional methods for determining the optimal segmentation scale of features (such as the homogeneity-heterogeneity method, the maximum area method, and the mean variance method), in which only the spectral and geometrical characteristics are considered, while the textural characteristics are neglected. Based on this, the Quickbird and unmanned aerial vehicle (UAV) images obtained in Xiyu Village, Pengzhou City, Sichuan Province, China, were selected as experimental objects, and the texture mean and spectral grayscale mean method (MANC method based on GLCM), which comprehensively considered the spectrum, shape, and texture features, was proposed to calculate the optimal segmentation scale of cultivated land in the study area. The error segment index (ESI) and centroids distance index (CDI) were adopted to evaluate image segmentation quality based on the method of area and position differences. The experimental results show that the MANC method based on GLCM can obtain higher segmentation precision than the traditional methods, and the segmentation results are in good agreement with the cultivated land boundary obtained by visual interpretation.

In this study, we fabricated the novel Ag3PO4 modified tubular porous carbon nitride (Ag3PO4@TPCN12) photocatalyst and evaluated its photocatalytic activity under the visible light irradiation in the presence of peroxymonosulfate (PMS) through carbamazepine (CBZ) degradation in water. The apparent rate constant in Vis/10%Ag3PO4@TPCN12/PMS system (0.0927 min-1) exhibited great superiority over that in Vis/TPCN12/PMS (0.0227 min-1), Vis/Ag3PO4/PMS (0.0019 min-1), and even Vis/(Ag3PO4+TPCN12)/PMS (0.0646 min-1) systems. Importantly, a wide pH tolerance (3.0-9.0) was shown in Vis/10%Ag3PO4@TPCN12/PMS system. Multifarious reactive species involving SO4•−, HO•, 1O2, and photo-generated holes primarily responsible for the CBZ degradation were verified. The degradation pathways of CBZ were proposed, and the ecotoxicity of CBZ degradation products was assessed. In general, the Vis/10%Ag3PO4@TPCN12/PMS system was capable of high stability and benign resistance of water matrix, showing a hopeful practical application potential for organic compounds degradation in water.

To improve soil aggregation through proper fertilization is very important for enhancing soil quality and crop productivity. However, the response of soil aggregation varies with the fertilization practices. The objective of this study was to determine the effects of long-term application of inorganic fertilizer, straw and manure on water-stable aggregate distribution (>2 mm, 0.25–2.0 mm, 0.053–0.25 mm, and P + . Consequently, the straw incorporation promoted the formation of >2 mm macroaggregates significantly ( P P > 0.05). The SOC, GRSP and MBC played an important role in the formation and stabilization of 0.25–2.0 mm aggregates. Our results indicate that animal manure may degrade soil structure due to the high salt content but straw incorporation is a judicious practice for sustainable agriculture in the Vertisol.

In cold regions, the surface cover plays a pivotal role in understanding the soil water and energy balance during winter. Although the effects of other types of surface cover on soil freezing-thawing process have been studied for decades, the effects of ice cover derived from irrigation remain unclear. To estimate the effects of ice cover on soil water, heat, and solute movement, ice coverage and field observation data were collected for three winter periods from 2013 to 2016 in Inner Mongolia, China. The collected data was then analyzed using the principal component analysis (PCA) method. The dynamics of the water, heat, and solute transport were also investigated using in-situ plot experiments conducted in four lysimeters, which were controlled by manipulating the thickness of the ice cover. The thickness of the ice cover was controlled by the amount of water irrigation in the treatment plots, and no irrigation was performed in the control plot. The results of the field-scale survey and PCA indicated that the ice cover had positive effect on soil salinization control and moisture preservation after autumn irrigation (AI). An unique air space created during the ice formation might enhance the heat insulation effect of ice cover. Furthermore, the results of the in-situ plot experiment revealed that the freezing of the irrigated soil could be divided into the unstable freezing period (UFP) and stable freezing period (SFP) when considering the ice cover. During the UFP, the upward movement of the solute that was leached by the irrigation water was reduced as the development of the freezing front was hindered by the irrigation water. During the SFP, the penetration of the freezing front was further reduced by the combination of the ‘inherited’ thermal regime from the UFP and the input solar energy reduced by the remaining ice cover and air space, which decreased the water and solute transport. The study findings aid in achieving an improved understanding of ice cover on agricultural fields in cold regions, and have important implications for water conservation and salinization control.

This study compared the temperature decays characteristics of weak plumes and strong plumes along the downstream longitudinal direction under natural ventilation. Experiments were carried out in a small-scale model tunnel to investigate the influence of fire plumes at different ceiling- fire source heights on the temperature distribution beneath ceiling. It is found that, the decay rate of temperature beneath ceiling induced by weak plumes is lower than that of strong plumes. And a new correlation is proposed by introducing the characteristic plume radius to predict the temperature decay of ceiling jet along the downstream longitudinal direction. The proposed model can provide well prediction to the present work and previous related data.

The front velocity of transient ceiling becomes an important consideration for tunnel fire safety, which provide a prediction of travel time of ceiling jet. The previous model predictions of ceiling jet front velocity were developed in a natural ventilation tunnel. The effect of central mechanical exhaust system on the ceiling jet front velocity have not been revealed in the past. This work experimentally revealed smoke front velocity of ceiling jet in a tunnel under the effect of central mechanical exhaust system, and the relative location between fire source and central exhaust system were considered. It is found that, the relative direction of fire source and ceiling mechanical extraction opening has a great influence on the smoke front velocity of ceiling jet. Some previous models (Jones, Benjamin, and CFAST) all overestimate the smoke flow velocity of ceiling front; the predicted ceiling jet front velocity deduced by Jones and Benjamin have the maximum excessive deviation of about 60% and 98%, respectively, but the CFAST model is closer to the measurements with relatively higher front velocity. The Hinkley’s model can be well used to predict it with different central mechanical exhaust system.

In this study, titanium borides reinforced Ti-6Al-4V composites have been successfully prepared by hot isostatic pressing (HIPing). The microstructure of the as-fabricated samples was investigated using X-ray diffraction technique, secondary electron microscopy and electron backscatter diffraction and the mechanical properties evaluated through micro-hardness and wear resistance measurements together with nano-indentation. It was found that during HIPing the additive particles TiB2 have transformed into TiB needles which tend to decorate at prior particle boundaries of the consolidated powder particles to form a network structure. Under the same HIPing condition, the needles became increasingly coarser and agglomerated with increased addition of TiB2. The micro-hardness of the synthesized materials increased with increased volume fraction of TiB. Nano-indentation measurement demonstrates that the TiB network structure shows much higher nanohardness than the surrounding matrix regions. The friction coefficient of the synthesized composites decreased continuously with increased volume fraction of TiB, indicating improved wear resistance. High resolution transmission electron microscopy analysis on wear debris revealed the formation of a series of oxides suggesting that chemical reaction between alloy elements and oxygen in air may have happened. It is thus believed that the wearing of the current samples is a result of both friction and chemical reaction.

The development of precision agriculture demands high accuracy and efficiency of cultivated land information extraction. As a new means of monitoring the ground in recent years, unmanned aerial vehicle (UAV) low-height remote sensing technique, which is flexible, efficient with low cost and with high resolution, is widely applied to investing various resources. Based on this, a novel extraction method for cultivated land information based on Deep Convolutional Neural Network and Transfer Learning (DTCLE) was proposed. First, linear features (roads and ridges etc.) were excluded based on Deep Convolutional Neural Network (DCNN). Next, feature extraction method learned from DCNN was used to cultivated land information extraction by introducing transfer learning mechanism. Last, cultivated land information extraction results were completed by the DTCLE and eCognition for cultivated land information extraction (ECLE). The location of the Pengzhou County and Guanghan County, Sichuan Province were selected for the experimental purpose. The experimental results showed that the overall precision for the experimental image 1, 2 and 3 (of extracting cultivated land) with the DTCLE method was 91.7%, 88.1% and 88.2% respectively, and the overall precision of ECLE is 90.7%, 90.5% and 87.0%, respectively. Accuracy of DTCLE was equivalent to that of ECLE, and also outperformed ECLE in terms of integrity and continuity.

Microvascular coupler devices have gained wide acceptance as an alternative to the traditional hand-sewn technique in reconstructive surgery. However, no study has directly compared the efficacy of the coupler and hand-sewn techniques in arterial anastomosis during head and neck reconstruction surgery. A total of 123 patients who underwent surgery performed by a single surgeon between 2016 and 2018 were included in this retrospective study. The patients were divided into the coupler group and the hand-sewn group according to the technique of arterial anastomosis used. Patients in the coupler group underwent a special procedure including arterial bifurcation to enlarge the recipient artery diameter. Of the 123 free flap surgeries performed, 56 were done using a coupler and 67 with the standard suture technique. One flap in the coupler group failed due to simultaneous arterial and venous thromboses. One flap in the hand-sewn group was lost due to venous compromise. The overall flap survival rate was 98.4% (n=121). There was a significant decrease in anastomotic time when a coupler was used (P

Diamond-like carbon (DLC) films were deposited on the nitrile butadiene rubber substrates by magnetron sputtering. The effects of the Ar sputtering pressure (SP) on the surface topography, structure, wettability and tribological performance of the DLC films were investigated. The DLC films' morphology as a function of SP was studied by atomic force microscopy, and their structural properties were investigated using Raman spectroscopy and FTIR. The Raman results revealed that a high SP contribute to forming sp3 bonds. The surface energy was calculated by the Owens-Wendt-Rabel-Kaelble method, and it peaked at a SP of 1.4 Pa. Tribological tests were performed using a ball-on-disc tribometry at a fixed load of 0.3 N under ambient conditions, which revealed that the tribological characteristics of DLC films can be tuned by varying the SP. The results showed that the DLC films prepared under 1.4 Pa SP exhibited enhanced triboperformance, based on a stable coefficient of friction lower than 0.25 during the whole test, which was very promising for practical tribological applications.

In this work, the failure mechanism of four high-strength valve springs were investigated. It shows that the premature fatigue failure of valve spring can be attributed to the presence of an intergranular surface crack formed by the environment-assisted cracking (EAC) mechanism. The surface cracks significantly reduces the fatigue strength to a level of 320–350 MPa, which is much lower than the designed stress (720 MPa). Detailed analysis reveal that the reduced shot peening effect caused by the soft and brittle PbO adhesion contributes to the occurrence of EAC. Furthermore, it suggests that the nucleation and propagation of EAC crack controls the failure process.

Flash floods are among the most dangerous natural disasters. As climate change and urbanization advance, an increasing number of people are at risk of flash floods. The application of remote sensing and geographic information system (GIS) technologies in the study of flash floods has increased significantly over the last 20 years. In this paper, more than 200 articles published in the last 20 years are summarized and analyzed. First, a visualization analysis of the literature is performed, including a keyword co-occurrence analysis, time zone chart analysis, keyword burst analysis, and literature co-citation analysis. Then, the application of remote sensing and GIS technologies to flash flood disasters is analyzed in terms of aspects such as flash flood forecasting, flash flood disaster impact assessments, flash flood susceptibility analyses, flash flood risk assessments, and the identification of flash flood disaster risk areas. Finally, the current research status is summarized, and the orientation of future research is also discussed.

A series of experiments were carried out in a model-scale tunnel [72 m (length) × 1.5 m (width) × 1.3 m (height)] to investigate the buoyant flow stratification behaviors in a tunnel fire with complexity of combination of longitudinal ventilation and ceiling extraction, which had not been studied before. The horizontal traveling velocity and vertical temperature profile were measured. The buoyant flow stratification conditions were visualized by a laser-sheet, as well as determined objectively by the vertical temperature profile measured. Buoyancy and inertial force are the two important factors influencing the buoyancy stratification. The interaction between them can be expressed by the Froude number or Richardson number. It was found that the buoyant stratification pattern was divided into three regimes. At regime I (Ri > 2.0 or Fr 0.8), a strong mixing existed between the upper buoyant flow and the lower air flow, that the buoyant flow stratification became unstable.

This paper investigates experimentally the effect of cross-wind on near-wall buoyant turbulent diffusion flame length and tilt, which has not been quantified in the literatures. Comprehensive experiments are conducted in a wind tunnel [66 m (Length) × 1.5 m (Width) × 1.3 m (Height)] employing a 5 cm square gaseous fuel sand box burner as fire source. Two different fire source positions are considered: at the middle of the two side wall (middle flame) or close to the side wall (near-wall burning) of the wind tunnel. The cross-wind speeds are ranged in 0–1.6 m/s. It was found that the mean flame length of near-wall burning is significantly higher than that of middle flame (free burning) for a given source heat release rate and cross-wind speed. However, for both burning conditions, the flame length firstly decrease, then increase and finally decrease again with increase in cross-wind speed. Non-dimensional correlations are proposed for the increasing regime of flame length against the Froude number ( Fr ), with two different coefficients suggested for these two burning conditions, respectively. The flame tilt angle is relatively smaller of near-wall burning than that of free burning for a given source heat release rate and cross-wind speed. The evolutions of the tangent values of the flame tilt angle are correlated non-dimensionally against a previously proposed global parameter including both heat release rate and cross-wind speed, accounting for the competition of the inertial force of the cross-wind with the buoyancy force of the fire source. The measured data are shown to be well correlated, with two different coefficients found for the two burning conditions, respectively.

Poisonous and harmful smoke is one of the most important factors in the life-threatening in tunnel fires. In the event of fire, the effective control of fire growth and smoke sinking is crucial for personnel security in tunnel. The aim of this work is to study the smoke thermal stratification with ceiling extraction in a longitudinal ventilated tunnel. A series of experiments were carried out in a 1/6 scale model tunnel [72 m (length) × 1.5 m (width) × 1.3 m (height)]. Four thermocouple trees are used to measure vertical temperature profile. The heat release rate, ceiling extraction velocity and longitudinal forced air flow velocity were considered. It was found that: (a) the smoke temperature below the tunnel ceiling decreased and the thermal stratification stability reduced with the increasing of ceiling extraction velocity; (b) the measured temperatures ratios ΔTcf/ΔTh versus ΔTcf/ΔTavg with and without ceiling extraction are in good agreement with Nyman and Ingason’s work; (c) with the coupling effect of ceiling extraction and longitudinal forced air flow, a modified Froude number was proposed to describe the influence of ceiling extraction, and the relation between the smoke thermal stratification and the modified Froude number agree well with Nyman and Ingason’s model.

This paper investigates experimentally the thermal buoyant smoke back-layering flow length beneath the tunnel ceiling with combination ceiling extraction and longitudinal ventilation, especially focusing on the condition that the ceiling extraction is employed at upstream side of the fire source, which has not previously been reported. Experiments are conducted in a model tunnel. A square gas burner was used to simulate the fire source, whose side dimension is 0.3 m. The heat release rates (HRRs) of fire source were 30 kW, 40 kW and 50 kW. Ceiling extraction opening with circular outlet of 0.3 m diameter was located at 1 m upstream from the fire source. Six different longitudinal ventilation velocities with six different ceiling extraction flow velocity were considered. Thermocouples are employed to measure the longitudinal temperature profile of the thermal smoke flow beneath the tunnel ceiling, to determine the upstream back-layering flow length. It was found that the upstream back-layering flow length increases with increase in heat release rate, meanwhile decreases with increase in longitudinal ventilation velocity or ceiling extraction velocity. A new non-dimensional factor was proposed to predict the thermal smoke back-layering flow length, which is shown to be in good agreement with the experimental results.

This paper reveals effect of smoke exhaust openings arrangement on the smoke spread performance in the tunnel fire of semi-transverse smoke extraction mode. Results show that the smoke back-layering can be significantly affected by the upstream openings arrangement in tunnel fires. As the more exhaust openings added to upstream, the smoke back-layering length becomes stronger and smoke spread rate remarkably increase. Moreover, the maximum smoke temperature above the fire source also remarkably increase due to combined effect of longitudinal air flow and the amount of smoke exhaust increased in upstream from the fire. Consequently, the fire risk to the blocked occupants and the tunnel structure increase in upstream. This research can contribute to the design of fire safety facilities and management of fire emergency in tunnels with similar conditions.

This paper reports a new global relation developed to characterize burning behavior of acetone pool fire under crosswind ranged from 0 to 2.5 m/s with incremental change of about 0.5 m/s. With the increase of the cross air flow speed, results show that the enhancement rate of the mass burning rate relative smaller pool fires was higher than relative larger pool fires. And the overall mass burning rate of the pool fire increases linearly with the cross air flow speed from 0 to 0.5 m/s, the mass burning rate increase with the increase of cross air flow speed. Then it began to drop a bit slightly. Finally, the mass burning rate gradually increased as the cross wind speed increases from 1.5 to 2.5 m/s. A global correlation by introducing the diffusive transfer B number, with wind speed and pool dimension aspect ratio accounted for, is then developed for the mass burning rate of square acetone pool fires. The mean flame length of acetone pool fires is well correlated linearly with Froude number. And the tangent values of flame tilt angle with cross air flow can be correlated well by previous model.

Reference evapotranspiration (ET0) is the key factor for hydrologic water balance, irrigation scheduling, and water resources planning. Based on Food and Agriculture Organization (FAO) Penman–Monteith method and the climate variables of 57 meteorological stations from 1960 to 2010 in southwest China, the spatial and temporal distributions of ET0 were analyzed by using Mann–Kendall test and Sen’s slope estimator. Sensitivity coefficient was used to analyze the sensitivities of ET0 to four climate variables, and the key climate variables attributed to ET0 change were determined. Result showed that there was a slight downward trend of ET0 from 1960 to 2010 and spatially increasing trend from northeast to southwest in annual time scale. Results also showed that ET0 had relatively higher sensitivity to wind speed and mean air temperature, and wind speed was the dominant variable for change of ET0 in southwest China. The inverse relationship between increasing air temperature and decreasing evaporation, “evaporation paradox,” existed in southwest China, and the negative contribution of wind speed to the changes of ET0 offset the positive contribution of air temperature.

We have synthesized and investigated the magnetic properties of the layered oxyselenides Sr 2 Co 1 − x Mn x O 2 Cu 2 − δ Se 2 (0 ⩽ x ⩽ 1). They crystallize in an unusual intergrowth structure with Cu 2 Se 2 and (Co,Mn)O 2 layers separated by Sr ions. The refinement of the X-ray diffraction data reveals an increase in the copper-deficiency when Co is substituted by Mn, which is caused by oxidization of Mn 2+ ions. The antiferromagnetic (AFM) transition temperature ( T N ) shifts to lower temperature and the dominant in plane interaction changes from AFM to ferromagnetic (FM) with Mn doping. The coexistence of AFM order and SG state is observed for compositions with 0.25 ⩽ x ⩽ 0.5.

This study was conducted to evaluate the effects of yeast culture (YC) supplementation on the growth performance, apparent nutrient digestibility and caecal microflora of broiler chickens. A total of 360 one-day-old Arbor Acres broiler chickens were randomly assigned to six dietary treatments containing 0.2%, 0.4%, 0.6%, 0.8% and 1% YC. The experiment lasted for 42 days. Diet and faecal samples were collected for analysis of dry matter, crude protein, ether extract, calcium and phosphorus. Caecal microbiota on days 21 and 42 were measured using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and real-time PCR. Dietary supplementation with YC did not affect feed intake. On day 42, the 0.8% YC group showed optimal growth and feed efficiency, as well as higher levels of apparent digestibility of ether extract, calcium and phosphorus. On day 21, both 0.8% and 1% YC groups exhibited a significant increase in Ruminococcus , Propionibacterium clostridiales , and Bifidobacterium density. The density of Bacteroides in the YC groups was significantly higher than that of the control group. On day 42, the densities of Bacteroides , Sphingomonas and Bifidobacterium were higher in the 0.8% YC group, whereas a significant decrease was observed in the number of Enterobacteriaceae . These results serve as evidence that dietary supplementation with 0.8% YC not only moderately optimized the feed efficiency and the apparent digestibility of ether extract, calcium and phosphorus, but also positively influenced the caecal bacterial density and diversity in broiler chickens. Keywords: Arbor Acres broiler, caecal microflora, yeast culture supplementation

Layered manganese oxyselenide Sr 2 F 2 Mn 2 Se 2 O was predicted from the stacking of the fluorite type block [Sr 2 F 2 ] 2+ alternating regularly with the anti-CuO 2 -type Mn 2 O square planar layer and successfully synthesized using solid state reaction under vacuum. The compound crystallizes in the layered tetragonal structure with I4/mmm space group and shows a semiconducting behavior. The large discrepancy between activation energy for conductivity, E ρ = 205 meV, and thermopower, E S = 41.7 meV, indicates its polaronic transport type. The compound has strong frustrated magnetic correlation, which gives rise to low-dimensional short-range ordering at high temperature with a small-angle canted antiferromagnetic (AFM) spin lattice. Furthermore, a short-range to long-range AFM phase transition is observed at about 141 K, in accord with the small heat capacity anomaly.

We grew pure 1T/2H-TaS2 single crystals via the chemical vapor transport (CVT) method and introduced defects into the samples by quenching. We systematically investigated the influence of defects on charge–density–wave (CDW) and superconductivity (SC) in 1T and 2H-TaS2. The defects can induce SC to 1T-TaS2 system, and inhibit the commensurate CDW (CCDW) and Mott insulator phase, the superconducting transition temperature ( T c Onset ) is about 2.5 K and the zero resistivity temperature ( T c zero ) is about 0.7 K. For 2H-TaS2, the defects nearly have no effect on CDW, while T c Onset is increased to about 2.7 K. The magnetization hysteresis loops show typical type-II superconductor behaviors for both 1T and 2H-TaS2 systems.

The multi-temperature refrigerated trucks which can transport a variety of goods at the same time, meet the requirement of production and marketing mode of “small production/big market” for Chinese agricultural products. In this paper, the multi-temperature refrigerated trucks with sidewall air duct and bottom return rail were selected to simulate the effect of air outlet locations and wind speed on the flow field of the carriage. The layout of the air outlet location and the wind speed was optimized accordingly.