利用掩星弯曲角协方差变换法确定对流层顶

利用气象电离层与气候观测星座（The Constellation Observing System for Meteorology,Ionosphere,and Climate,COSMIC）任务提供的全球定位系统（Global Positioning System,GPS)无线电掩星观测数据,研究用弯曲角自然对数协方差变换确定对流层顶的方法.对该方法中尺度因子a值的选取原则进行了讨论,发现当a取35 km时,基本能过滤低对流层大气温度和湿度梯度引起的小尺度变化,最易确定对流层顶高度.〖JP2〗将采用该方法确定的对流层顶分别与相应的掩星温度廓线确定的温度最低点对流层顶（Cold Point Tropopause,CPT）和温度递减率对流层顶(Lapse Rate Tropopause,LRT)、以及无线电探空温度廓线确定的CPT和LRT进行了比对,结果表明:直接从弯曲角廓线出发,采用自然对数协方差变换法确定对流层顶是可行的;在某些高纬度地区,弯曲角自然对数协方差变换法比其它方法更加实用.     

丙酸杆菌素的发酵及其分离纯化的初步探究

本文以薛氏丙酸杆菌(Propionibacterium shermanii)发酵液为原料,以抑菌活性为指标,利用分离纯化技术提取发酵液中小分子丙酸杆菌素。丙酸杆菌素初步分离纯化确定的最佳脱盐条件为:上样量5 m L,流速0.5 m L/min,收集方式为手动收集,电导率达到1.5 ms/cm时停止收集;Superdex peptide最佳凝胶过滤条件为:上样量500μL,流速0.5 m L/min,深孔板固定体积收集,每孔收集体积200μL。最终得到一种分子量为698.9556 u的丙酸杆菌素,其单位抑菌活性为初始的6.8倍,抑菌活性得率为10.9%。酶解实验表明纯化后的丙酸杆菌素仍保留抑菌活性,且对胃蛋白酶敏感。      

粗制及精制蓝靛果花色苷的稳定性和抗氧化性研究

通过对蓝靛果花色苷的提取粗制品和纯化的精制品进行稳定性和体外抗氧化活性的比对实验,考察了p H、光照、温度、过氧化氢、糖等对蓝靛果花色苷稳定性的影响,并比较了其总还原力和清除DPPH自由基、羟自由基的抗氧化性能力。结果表明:在避光和p H为1、3的条件下,蓝靛果花色苷的保存率达85%以上,稳定性较好,且花色苷粗制品的稳定性优于精制品;随着处理温度的升高,花色苷的稳定性急剧下降,在50℃以下花色苷较稳定;在一定浓度范围内,葡萄糖、乳糖、蔗糖和淀粉对蓝靛果花色苷稳定性均具有增强作用,过氧化氢对花色苷有严重的破坏作用,且花色苷粗制品的耐氧化性明显强于精制品。此外,抗氧化性对比实验发现蓝靛果花色苷具有较强的还原能力,清除DPPH自由基、羟自由基的能力,通过比较花色苷粗制品及精制品的EC50值可知,这两种花色苷制品的总还原能力及清除羟自由基的能力略弱于同质量浓度的VC,但清除DPPH自由基的能力均强于同质量浓度的VC,且花色苷精制品的抗氧化能力明显强于粗制品。      

UV-C处理对双孢蘑菇采后品质的影响

本文以双孢蘑菇为材料,研究了不同剂量的短波紫外线（UV-C）对双孢蘑菇低温贮藏期间的失重率、硬度、颜色、可溶性固形物含量、细胞膜透性、PPO活力和微生物的影响。双孢蘑菇子实体先用0、0.3、0.6、0.9、1.2 k J/m2剂量的UV-C处理,随后放入4℃冷库存放16 d。结果表明:适当的短波辐照（0.6 k J/m2）处理可以抑制细胞膜透性的增加,延缓可溶性固形物含量的降低,在一定程度上延缓软化和褐变。对嗜冷菌、大肠杆菌、酵母和霉菌有显著性抑制作用。较大剂量（0.9、1.2 k J/m2）会对双孢蘑菇的表皮细胞产生伤害,使得细胞膜透性增加,导致可溶性固形物含量的降低,失重率增加以及褐变的加剧。      

普洱茶渥堆发酵过程中金属元素的变化研究

以三级晒青毛茶为原料,设置不同的翻堆次数,研究普洱茶渥堆发酵过程中金属元素的变化情况。结果表明:随着翻堆次数的增加,铁、锰呈螺旋式增加趋势,渥堆结束时,分别增加77%、13%;锌含量呈增加趋势,渥堆结束时增加33%,铜呈螺旋式降低趋势,渥堆结束时降低4%。重金属镉、铬呈螺旋式增加趋势,渥堆结束时,分别增加12%、16%,铅呈增加趋势,渥堆结束时增加18%,砷含量先减少后增加,渥堆结束时增加8%。稀土氧化物总量呈增加趋势,渥堆发酵结束后,稀土氧化物总量增加1.1倍。研究结果表明渥堆发酵过程中不同的翻堆次数,茶叶金属元素的变化较为明显,且不同发酵层的金属元素变化不同,为普洱茶渥堆发酵过程产品质量安全提供了一定技术支撑。      

The Role of Circular RNAs in the Physiology and Pathology of the Mammalian Ovary

Circular RNAs (circRNAs) are an abundant class of endogenous non-coding RNAs (ncRNAs) generated from exonic, intronic, or untranslated regions of protein-coding genes or intergenic regions. The diverse, stable, and specific expression patterns of circRNAs and their possible functions through cis/trans regulation and protein-coding mechanisms make circRNA a research hotspot in various biological and pathological processes. It also shows practical value as biomarkers, diagnostic indicators, and therapeutic targets. This review summarized the characteristics, classification, biogenesis and elimination, detection and confirmation, and functions of circRNAs. We focused on research advances circRNAs in the mammalian ovary under conditions including ovarian cancer, polycystic ovarian syndrome (PCOS), and maternal aging, as well as during reproductive status, including ovarian follicle development and atresia. The roles of circRNAs in high reproductive traits in domestic animals were also summarized. Finally, we outlined some obstructive factors and prospects to work with circRNA, aiming to provide insights into the functional research interests of circRNAs in the reproduction and gynecology areas.     

Identification and Functional Analysis of Key Autophosphorylation Residues of Arabidopsis Senescence Associated Receptor-like Kinase

Reversible protein phosphorylation mediated by protein kinases and phosphatases plays important roles in the regulation of leaf senescence. We previously reported that the senescence-associated leucine-rich repeat receptor-like kinase AtSARK autophosphorylates on both serine/threonine and tyrosine residues and functions as a positive regulator of Arabidopsis leaf senescence; the senescence-suppressed protein phosphatase SSPP interacts with and dephosphorylates the cytoplasmic domain of AtSARK, thereby negatively regulating leaf senescence. Here, 27 autophosphorylation residues of AtSARK were revealed by mass spectrometry analysis, and six of them, including two Ser, two Thr, and two Tyr residues, were further found to be important for the biological functions of AtSARK. All site-directed mutations of these six residues that resulted in decreased autophosphorylation level of AtSARK could significantly inhibit AtSARK-induced leaf senescence. In addition, mutations mimicking the dephosphorylation form of Ser384 (S384A) or the phosphorylation form of Tyr413 (Y413E) substantially reduced the interaction between AtSARK and SSPP. All results suggest that autophosphorylation of AtSARK is essential for its functions in promoting leaf senescence. The possible roles of S384 and Y413 residues in fine-tuning the interaction between AtSARK and SSPP are discussed herein.     

Array-level boosting method with spatial extended allocation to improve the accuracy of memristor based computing-in-memory chips

Memristor based computing-in-memory chips have shown the potentials to accelerate deep neural networks with high energy efficiency.Due to the inherent filament-...     

诱导气流对转载点雾化特性影响规律的数值模拟与试验

为了解决疏水性煤尘难润湿、微米级粉尘降尘率较低等难题,选取1-丁基-3-甲基咪唑氯盐([Bmim][Cl])、1-丁基-3-甲基咪唑四氟硼酸盐([Bmim][BF₄])、1-乙基-3-甲基咪唑四氟硼酸盐([Emim][BF₄])3种咪唑类离子液体,开展不同变质程度的煤尘表面润湿特性试验研究,分析不同阳、阴离子数的复配活性水溶液对煤尘润湿性能的影响规律。结果表明,阳离子[Emim]⁺和[Bmim]⁺能有效屏蔽阴离子[BF₄]^-、Cl^-之间的静电相互作用,促进阴离子在气—液界面之间的吸附和聚集,致使表面张力、接触角均随活性水溶液的离子液体质量分数的增大而逐渐降低;咪唑阳离子侧链上的H原子与煤中的—OH、—COOH等基团形成氢键,破坏了煤中原有氢键,提高了离子液体对煤的溶解能力,长焰煤的润湿效果最好,褐煤次之,焦煤最差;复配后的活性水溶液通过破坏煤中官能团增强了对煤结构的溶解能力,降低了水的表面张力并提高溶液的润湿能力,复配溶液实现了协同增润作用,可为开发新型润湿剂提供新的思路和方向。