Search

In this study, we obtained a stable male sterile mutant abortive pollen 90 (ap90) from the mutant library of Zhonghui 8015 (wild-type, WT), an indica restorer line, induced by Ethyl Methy Sulfone (EMS). Compared to the WT, the ap90 mutant displayed no significant differences in plant height, plant type, tiller number, heading date and other agronomic traits, but the anthers were thinner, light creamy yellow and pollen grains were completely abortive. Semi-thin sections observation of anther development at different stages showed that the ap90 mutant carried an abnormal development process of anther wall cells. Namely, the tapetum cell degradation was obviously abnormal, the microspore cells could not form a normal pollen wall structure during mitosis and the starch filling process was blocked which eventually resulted in the degradation of microspores into threadlets and failure of anther dehiscence. Scanning electron microscopic (SEM) observations of the anther surface and pollen exine suggested that the anther epidermis of mutant ap90 were shrunk and covered by more compactly arranged cuticles. The shape of Ubisch distributed on the inner surface of anther locule were irregular, closely arranged and disordered. The pollen grains were shriveled and the sporopollenin on the pollen exine were abnormally arranged. Genetic analysis showed that the ap90 phenotype was controlled by a pair of recessive nuclear genes. Gene preliminary mapping located the mutation site into a 491.73 kb interval between RM21421 and RM21435 on the long arm of rice chromosome 7. Further Mut-Map sequencing analysis confirmed that there was a 37 bp deletion and a following single base substitution in the second exon region of LOC_Os07g22850 in the ap90 mutant, which resulted in the shifted coding sequence, prematurely terminated transcription and translation, leading to the entire abortive pollen and sterile spikelet in the ap90 mutant. Expression pattern analysis results demonstrated that the OSAP90 gene was specifically expressed in anthers and the OsAP90 protein was mainly located in the endoplasmic reticulum (ER). The qPCR results suggested that the relative expression level of many male sterility-related genes in the ap90 mutant was affected by the mutation site, which further proved that 0sAP90 played an important role during the formation of Ubisch and pollen wall in rice anther development. [ABSTRACT FROM AUTHOR]

A thermal conductive gasket was prepared by vinyl silicone oil as base material and low density thermal conductive ceramic powder. The compounding method and content of different types of thermal conductive ceramic powder, the viscosity of vinyl silicone oil, the amount of surface treatment agent and feeding sequence of thermal conductive powder were analyzed. The results show that the overall performance of the thermal conductive gasket prepared by boron nitride/spherical silicon powder is better than that by boron nitride/aluminum hydroxide. Vinyl silicone oil with a viscosity of 500 mPa-s can meet the requirements for mechanical properties of thermal conductive gaskets. When the amount of surface treatment agent is 0. 8 g, the powder is evenly dispersed in the gasket. In the preparation of the compounds, spherical silicon powder is added first to increase the viscosity of the system, then boron nitride is added after stirring for a while. The feeding process improves the dispersion of boron nitride and optimize the performance of thermal gasket. The thermal conductive gasket has been prepared with 4 g vinyl silicone oil as the base material, 85 g boron nitride and silicon micropowder(mass ratio of 1:5), crosslinking agent and catalyst as the thermally conductive filler. It has a density of 2. 0 g/cm and the thermal conductivity of 2. 0 W/( m - K), which can meet the requirements of low-density thermal gasket. [ABSTRACT FROM AUTHOR]

Objective To investigate the role of cerebrospinal fluid (CSF) and serum procalcitonin (PCT) in diagnosis of post - neurosurgical bacterial meningitis/ventriculitis (PNBM/BV) in patients with aneurysmal subarachnoid hemorrhage (aSAH). Methods A prospective observational study was conducted, and 53 patients with suspected bacterial meningitis after craniotomy were selected from June 2018 to June 2019 in Department of Neurosurgical Intensive Care Unit in Xuanwu Hospital of Capital Medical University. The patients were divided into PNBM/BM group (25 cases) and non-PNBM/BV group (NPNBM/BV, 28 cases). CSF cells count, white blood cell count (WBC), protein quantity and glucose, blood glucose and CSF/blood glucose ratio, and CSF and serum PCT were measured. Pearson correlation analysis and partial correlation analysis were used to explore the correlation between CSF PCT and CSF and serum indicators. The receiver operating characteristic curve (ROC curve) and calculate the area under the curve (AUC) were drawn, and the sensitivity and specificity of CSF and serum PCT in the diagnosis of PNBM/BV were calculated. Results CSF WBC (P = 0.011), protein quantity (P = 0.030), PCT (P = 0.000) and serum PCT (P = 0.010) in PNBM/BV group were higher than those in non-PNBM/BV group, while CSF glucose (P = 0.000) and CSF/serum glucose ratio (P = 0.000) in PNBM/BV group were lower than those in non-PNBM/BV group. Correlation analysis showed that PCT in CSF was positively correlated with serum PCT (r = 0.421, P = 0.002) and CSF WBC (r = 0.394, P = 0.004), but negatively correlated with CSF glucose (r = - 0.327, P = 0.018). The ROC curve showed the AUC of CSF PCT in the diagnosis of PNBM/BV was 0.835 (95%CI: 0.710-0.960, P = 0.000), the sensitivity was 88%, the specificity was 82.10%, the positive predictive value was 81.48% (22/27), the negative predictive value was 88.46% (23/26), and the diagnostic cutoff value was 0.331 ng/ml. The ROC curve showed the AUC of serum PCT for the diagnosis of PNBM/ BV was 0.720 (95% CI: 0.580-0.860, P = 0.000), the sensitivity was 64%, the specificity was 75%, the positive predictive value was 69.57% (16/23), the negative predictive value was 70% (21/30), and the diagnostic cutoff value was 0.501 ng/ml. Conclusions Detection of CSF and serum PCT has important clinical application value in the diagnosis of PNBM/BV after aSAH. [ABSTRACT FROM AUTHOR]

A two-component silicone gel for the power battery case was prepared by a high" and low-viscosity vinyl silicone oil, a hydrogen-ended silicone oil and a hydrogen-sided silicone oil as the raw materials. The effects of the amount of vinyl silicone oil with low viscosity, hydrogen "terminated silicone oil and the active hydrogen content of the hydrogen-sided silicone oil on the properties of the silica gel were discussed. Results show that the silica gel has the excellent performance when the vinyl silicone oil (low-viscosity) is 12%, the hydrogen-terminated silicone oil is 2. 0%, and the hydrogen-ended silicone oil is 0. 36%. The silicone gel prepared meets the requirements of air-tightness of the power battery case, IPX8 waterproof performance, and UL94 V-0 flame retardancy. It also ensures the power battery case be automatically constructed and easy to repair r and can be repeatedly disaasembled and reworked. [ABSTRACT FROM AUTHOR]

The qualitative and quantitative analyses of the wear resistance and thermal endurance of QSn5 ~7-0. 2 ~0. 4 copper alloy block were performed with stepwise-loading method under the circumferences of grease lubrication and dry friction, respectively. The wear resistance was evaluated by measuring the test block's average volume abrasion ratio while the adhesion resistance, namely thermal endurance, was assessed by monitoring the test block's temperature variation in real time. The results reveal that the wear resistance of this kind of material, especially the adhesion resistance, is excellent and its permissible operating temperature is relatively high. The friction coefficient between the test block and the cylindrical ring is smaller and its temperature rise is lower, its wear resistance is exponentially improved and its thermal endurance is preferable under grease lubricating condition. [ABSTRACT FROM AUTHOR]

The article discusses a study on the development of polymerase chain reaction (PCR) for detection of goat poxvirus (GPV) in affected cells and pock samples of fowlpox.

Collaborative filtering is a widely used technique in current recommendation systems.It leverages the similarity between different users or items to retrieve interactive information between users and items and recommends new items for target users.In recent years,graph learning has gradually become an emerging recommendation paradigm due to its excellent perfor-mance and scalability in graph representation learning.This paper systematically reviews the most recent research on recommendation field from the perspective of graph learning.First,we provide a taxonomy that groups the current recommendation scenarios into two categories according to the data type used,including recommendation systems based on interactive information that leverage user-item interaction data as the main data source and auxiliary information-enhanced recommendation systems that incorporate social information associated with users and items as well as the knowledge graph information.Then,we review the main approaches,fundamental algorithms and critical difficulties of current recommendation models from the perspectives of random walk,graph representation learning and graph neural networks.Finally,we summarize the main challenges of graph learning methods in the field of recommendation system and outline the possible future research directions.

A blind linear receiver for multi-antenna impulse radio ultra-wideband（UWB）communication systems was proposed.Without the need of channel information,specific properties of the received data imposed by the precoded space-time block codes（STBC）could be exploited to estimate the coefficients of the receiver,which subsequently recovered the transmitted symbols.Simulations show that,with the increasing of the data block for estimation,the performance of the blind receiver approaches that of the coherent one.