Subjects: Biology >> Ecology submitted time 2023-07-06
Abstract： Watershed biological information flow (WBIF) is defined as the path, processes and control of biological information transport, exchange, interaction and feedback among different spaces and systems along with watershed ecosystem processes, and could be partly described as the land-to-river and upstream-to-downstream bioinformation transportation (including organisms, nucleic acids, peptides and other biomarkers), which is driven by the hydrologic processes of watershed systems. The WBIF labels the transport of organic matter and energy. The WBIF integrates the ecological processes of environmental DNA (eDNA), including the origin, state, transport, and fate of eDNA, and makes it possible that the species composition in river system is monitored and assessed using eDNA. The WBIF estimation is the key for watershed ecosystem processes studying and riverine biodiversity monitoring. However, in practice, the parallel samples in each sampling site always are limited. And how parallel samples would impact WBIF estimation is unknown. Based on the principles of sampling survey, we hypothesized that parallel samples would not impact the accuracy of the WBIF estimation, but affect the precision of the WBIF estimation. Then, we transformed this hypothesis into a set of formulas and tested it with a series of analog computation. Results showed that the number of parallel samples (efficiency of detection) affected both the accuracy and precision of the WBIF estimation. The optimal WBIF estimation was less than the actual WBIF in any condition. Along with the increase of parallel samples (efficiency of detection), the optimal WBIF estimation gradually neared to the actual WBIF, the range of WBIF estimation gradually focused on the actual WBIF. In other words, more parallel samples (higher efficiency of detection) led higher accuracy and precision of the WBIF estimation. In addition, the actual WBIF affected both the accuracy and precision of the WBIF estimation too. Larger actual WBIF led higher accuracy and precision of the WBIF estimation. The relative relationship between the number of biological information types in upstream and downstream samples affected both the accuracy and precision of the WBIF estimation too. The accuracy and precision of WBIF estimation would be higher when the number of biological information types in upstream samples was more than those in downstream samples. So, we suggest that in the work of watershed ecosystem processes studying and riverine biodiversity monitoring, the relationship between parallel sample number and detection efficiency should be assessed, the suitable parallel sample number should be estimated based on the reliability target of WBIF estimation, the sampling program should be designed with suitable parallel samples, the WBIF should be estimated based on all parallel samples of each sampling site, at last the estimated results of WBIF should be re-evaluated according to the posterior probability of WBIF in different conditions. The current work provided the framework and methodology reference for the post-evaluation.
Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-31 Cooperative journals: 《中国腐蚀与防护学报》
Abstract： One oxidation-condensate immersion cyclic method was used to simulate muffler internal service environment under the long-distance driving conditions. The corrosion behavior of type 409, 429, 436, 439 and 441 stainless steels was investigated in the condensate solutions. The results show that the oxidation/corrosion product films on the surfaces of these five steels are mainly composed of Cr2O3 and Fe2O3. The alloying elements Cr and Mo play the most important role in the resistance of product films and charge transfer processes on steel surfaces. Pit depth decreases in order of 409, 439, 441, 429 and 436, but there is small depth difference between 439 and 441 as well as 429 and 436. Moreover, these five stainless steels show good pit resistance in the simulated processes of long-distance driving trips.
Subjects: Materials Science >> Materials Science (General) submitted time 2023-03-31 Cooperative journals: 《腐蚀科学与防护技术》
Abstract： The corrosion behavior of type 304 and 441 stainless steels was investigated in a simulated environment of diesel exhaust selective catalytic reduction (SCR) system by using a two step tests, i.e. first the steels were suffered from hot exhaust gas oxidation at 600 ℃ for 100 h and then immersed in a simulated condensates solution at 80 ℃ to reveal their electrochemical corrosion characteristics. The results indicate that, after oxidation at 600 ℃ in the exhaust gases with and without addition of urea respectively, 441 stainless steel shows passive corrosion state in the condensates solution, whereas 304 stainless steel is in active corrosion state. After polarization curve measurements, some pits formed on 441 stainless steel surface, and intergranular corrosion feature was observed on parts of 304 stainless steel surface. After the oxidation in hot exhaust gas with addition of urea, the aforementioned localized corrosion for both 304 and 441 stainless steels can be accelerated during the subsequent corrosion in the condensates solution.
Subjects: Biology >> Ecology submitted time 2023-03-28
Abstract： Environmental DNA (eDNA) is DNA extracted from any type of environmental sample (e.g. water, soil, sediment, air, mixture, etc.), which is a DNA mixture originated from different species and individuals, distinguish from a pure DNA sample extracted from a particular organism. eDNA monitoring refers the processes that 1) extracting DNA sample from environmental sample, 2) using definite species-specific primers or meta-barcoding primers to amplify and sequence eDNA sample, 3) clustering the operational taxonomic units (OTUs) and identifying their taxa against reference databases, 4) calculating the relative abundance of each OTUs/ species and other biodiversity indexes, 5) analyzing the corresponding ecosystem structure, processes or function. According to eDNA monitoring, a definite species (or other taxonomic units) in the sampling site could be identified, and the biological information about species composition, community structure, ecosystem processes, ecological function of the research area could be collected. eDNA monitoring has been applied in monitoring and early warning definite species, investigating and assessing biodiversity, detecting and analyzing community structure and function, studying and quantifying ecosystem processes and so on. eDNA monitoring could work in any type of environmental scene where there is unidentified DNA trace, such as in terrestrial environment, aquatic environment, air environment, body surface, organism (inner) surface and so on. As an emerging tool for documenting species presence without direct observation, allowing for sensitive and efficient detection, easy-to-standardize sampling and analyzing approach, comprehensive taxonomic groups coverage, less reliant on taxonomic expertise and auditable by third-party researchers, eDNA monitoring would be a prospective general method for species monitoring, community function predicting and ecosystem processes analyzing in future. Moreover, the objective scope of eDNA monitoring covers all environmental conditions and all biological taxonomies. However, to realize the prospective application vision of eDNA monitoring, there are ten crucial links that need to be standardized at both general level and definite level. 1) Design of duplicated samples for a region with definite environment conditions. The number of duplicated samples could be generally identified just using species accumulation curves. 2) Design of sampling time for a region with definite environment conditions. The interval of sampling time could be generally identified by quantifying the degradation ratio or the retention time of the eDNA from different taxonomic organisms in definite environment conditions. 3) Design of sampling sites for a region with definite environment conditions. The distance of sampling sites could be generally identified by quantifying the effective transportation distance or the spatial heterogeneity of the eDNA from different taxonomic organisms in definite environment conditions. 4) Design of sampling method. For different study areas, objects and aims, there are different optimal sample types (water, soil, sediment or other samples). Don’t combine different duplicated samples, or some rare species would be omitted because of their too weak signals. 5) Pretreatment of samples. Pretreatment of samples mainly refers filtration of water samples. It’s suggested that filtering water samples should use finer millipore glass fiber filter. Don’t remove large particles by prefiltering water sample, or some species signals could be removed. 6) Storage of samples. It’s suggested that samples could be stored at -20 or -80 centigrade, except water samples. Water samples should be kept cool in ice bath and be filtered as soon as possible. 7) Choosing of primers. The primers of metabarcoding of the 16S rRNA gene are widely used for detecting bacteria and archaea. The primers of metabarcoding of the ITS and 18S rRNA genes are widely used for detecting fungi. The primers of metabarcoding of the mitochondrial CO1, 12S rRNA and Cyt b genes are widely used for detecting metazoan. Metagenome is another choice for identifying species. 8) Experiment processes of DNA extraction, amplifying, sequencing and analyzing. As the experiment processes are more and more tending to be processed by commercial biolabs, a set of general experimental parameters is needed. 9) Taxonomic identification of OTUs. Good reference databases, either comprehensive reference databases or local customizable reference databases, are required. 10) Post-evaluation of results. Post-evaluation of results mainly pays attention on whether the number of duplicated samples is sufficient, whether the frequency of sampling is suitable, whether the spatial distance between sampling sites is suitable, whether the taxonomic identification of OTUs is accurate. Until now, there is no theoretical difficulty in standardizing these ten crucial links. Now, the mainly work is the accumulation of datasets and knowledge. Some studies on supporting the standardization have been processed. Parts of standardizing works have been organized both at home and abroad. We expect that the accumulation of crucial datasets and knowledge on eDNA monitoring in hot regions could finish in future several years, and then the eDNA monitoring could be a general work, even a long term basic work in hot regions. As the eDNA monitoring could produce comprehensive and standard datasets, along with the long term basic work of eDNA monitoring realizing, the long time series datasets could be used to detect the biodiversity (especially hiddenbiodiversity) variations and study the dynamic and evolution of ecosystem structure, processes, function and health. Moreover, we expect a series of datasets with high quality, rigour, availability and transparency in future to support the open science and the data-intensive scientific discovery and ecosystem management.
Subjects: Astronomy >> Astrophysical processes submitted time 2020-06-09 Cooperative journals: 《天文研究与技术》
Abstract：500米口径球面射电望远镜FAST已投入科学运行，漂移扫描巡天采集数据量已超过1PB，预计每年新增至少5PB。现有数据处理软件如PRESTO、SIGPROC等已无法满足PB量级数据的快速处理要求。提出了一种基于PRESTO的分布式并行计算方法，整合利用数据库技术和异地异构计算资源，构建了一套命名Craber的计算加速系统。整体系统由FAST早期科学数据中心与国家天文台团队共同设计和实现。启用Craber子网计算集群D中55个计算节点，应用Parkes多波束巡天数据集和FAST漂移扫描数据验证了系统流程和搜索数据库。单个100MB Parkes巡天数据文件平均耗时36秒，单个128MB FAST巡天数据文件平均耗时22秒。该系统目前已实际参与FAST数据处理并产生数十颗脉冲星发现，有效帮助FAST加速数据处理和扩大新样本数量。
Subjects: Astronomy >> Astrophysical processes submitted time 2019-04-17 Cooperative journals: 《天文研究与技术》
Abstract： 对新疆天文台(XAO)南山一米大视场天文望远镜（NOWT）观测的历史数据，我们进行细致的数据挖掘，发现了百余颗变源。数据处理pipeline为XAO时域巡天数据处理包，该处理包同时考虑了测光系统内部权重和相关性，并结合快速混合算法编写的。除去已知的变源，我们发现了很多新的变源。对新变源证认的过程中，我们将结果与LAMOST、GCVS、VSX、Gaia DR2等星表进行了交叉。在讨论部分，我们对各星表的使用情况给出了说明。对于新源最后发现绝大部分是食双星，少部分是脉动变星，并有一颗表现相对复杂的变源。
Subjects: Biology >> Botany >> Applied botany submitted time 2019-01-30 Cooperative journals: 《广西植物》
Abstract：杂交带是研究物种形成及进化的天然实验室，为探究棱果沙棘自然杂交带三种沙棘的生理生态适应性，在光照充足的 7 月中旬分别测定了该区域三种沙棘雌、雄株的光合特性及相关环境因子的日变化，以期为杂交带的维持机制提供理论依据。结果表明：同种沙棘雌、雄株间光合日变化规律基本一致；不同沙棘光合特性的日变化规律差异主要表现在：中国沙棘（Hippophae rhamnoides ssp. sinensis）Pn 日变化呈明显的双峰曲线，峰值出现在 PAR 和Ta 相对较高的 10:00 和 14:00，最高达到 19.53±5.35 μmol·m-2·s-1，棱果沙棘（Hippophae goniocarpa）和肋果沙棘（Hippophae neurocarpa ssp. neurocarpa）Pn 日变化均呈近双峰曲线，在 PAR 和 Ta 相对较低的 8:00 和 16:00 有较高的值，最高值分别为 13.43±3.43 和 15.27±2.43μmol·m-2·s-1；三种沙棘 WUE 与 Pn 的日变化规律一致，但中国沙棘具有最高的 WUE，达到6.72±0.95 μmol·mmol-1，棱果沙棘和肋果沙棘的 WUE 日变化最高分别为 4.03±1.08 和4.93±0.86 μmol·mmol-1；三种沙棘 Tr、Gs、Ci 和 Ls 的日变化规律相似，其中 Gs 均在 10:00后一致下降，在 12:00 左右均出现不同程度的气孔关闭的现象，这也是其发生光合午休的主要原因之一；杂交带三种沙棘光合特性日变化差异主要表现在中国沙棘和其它两种沙棘之间，而杂交种棱果沙棘与亲本种肋果沙棘的变化规律基本一致，其 Pn 与 WUE 可能受到了Ta、PAR 和 RH 等环境因子的影响。
Subjects: Biology >> Zoology submitted time 2018-12-25 Cooperative journals: 《动物营养学报》
Abstract：本试验以活体肉仔鸡为研究对象，以静脉注射方式外源导入促肾上腺皮质激素释放因子（CRF），分析肉仔鸡采食量的变化和下丘脑、肠道中食欲调控相关基因的表达情况，对CRF在肉仔鸡食欲调控中的作用进行探究。选取体重相近的1日龄雄性爱拔益加（AA）肉仔鸡20只，7日龄时随机分为2个组，每组10只鸡，单笼单饲。试验组肉仔鸡于10日龄08:00翅静脉注射1 000.0 μg/kg BW的CRF，对照组同时注射等量的生理盐水。注射2 h后，统计采食量，10日龄10:00进行屠宰取样，利用实时荧光定量PCR（RT-PCR）检测下丘脑、十二指肠、空肠和回肠中食欲相关基因胃饥饿素、促肾上腺皮质激素释放因子受体（CRFR）1、CRFR2、生长激素促分泌素受体-1α(GHSR-1α)mRNA相对表达量。结果表明，与对照组相比，静脉注射CRF显著降低了肉仔鸡采食量（P<0.05）；显著提高了肉仔鸡下丘脑中胃饥饿素和CRFR1 mRNA相对表达量（P<0.05），而下丘脑中CRFR2和GHSR-1α mRNA相对表达量无显著变化（P＞0.05）；显著提高了肉仔鸡十二指肠、空肠和回肠中CRFR1、CRFR2和GHSR-1α mRNA相对表达量（P<0.05），显著降低了十二指肠胃饥饿素mRNA相对表达量（P<0.05），而在空肠和回肠中胃饥饿素mRNA相对表达量无显著变化（P＞0.05）。由此可见，静脉注射CRF能降低肉仔鸡采食量，诱导中枢胃饥饿素的基因表达，下丘脑CRFR1、胃饥饿素以及肠道CRFR1、CRFR2、GHSR-1a基因表达上调导致的食欲抑制可能是造成采食量下降的原因。
Subjects: Biology >> Zoology submitted time 2018-12-25 Cooperative journals: 《动物营养学报》
Abstract：为揭示应激导致家禽肝脏代谢异常的机理，本研究探查了糖皮质激素——地塞米松（DEX）对鸡胚肝细胞脂肪和胆汁酸代谢相关基因表达的影响。选取19胚龄的无特定病原体(SPF)鸡蛋，原代培养鸡胚肝细胞（37 ℃、5% CO2），用0（对照）、200、500、1 000 nmol/L的地塞米松分别处理24 h。结果表明：与对照组相比，高剂量（500、1 000 nmol/L）地塞米松处理显著降低了脂肪代谢相关基因——脂肪酸转运蛋白1（FATP-1）、固醇调节元件结合蛋白-1C（SREBP-1C）、载脂蛋白B100（APOB100）、肝脏X受体（LXR）以及胆汁酸摄取相关基因Na+/牛磺胆盐共转运体（NTCP）的mRNA相对表达水平（P＜0.05），显著提高了胆汁酸排出相关基因——胆盐输出泵（BSEP）的mRNA相对表达水平（P＜0.05）；低剂量（200 nmol/L）地塞米松处理显著提高胆汁酸合成相关基因——胆固醇7-羟化酶（CYP7A1）和法尼酯X受体（FXR）的mRNA相对表达水平（P＜0.05），同时，SREBP-1C的mRNA相对表达水平显著降低（P＜0.05），BSEP的mRNA相对表达水平显著上升（P＜0.05）。由此表明，高剂量糖皮质激素对鸡胚肝细胞的脂肪合成、转运和胆汁酸的摄取具有抑制作用；低剂量糖皮质激素可以促进胆汁酸的合成和排出，部分反应具有剂量依赖性。
Subjects: Biology >> Zoology submitted time 2018-12-25 Cooperative journals: 《动物营养学报》
Abstract：本试验旨在探讨不同泌乳阶段的高产与低产奶牛血清营养状况指标与抗氧化指标的变化规律，并建立血清营养状况指标与抗氧化指标的多元线性回归模型。采用2×6（产奶量：高产≥35 kg/d和低产＜35 kg/d；泌乳阶段：围产前期、围产后期、泌乳前期、泌乳中期、泌乳后期和干奶期）双因素完全随机试验设计，将240头体重[（550±10） kg]、胎次[（2.08±0.47）胎]、体况（3.0～3.5分）、饲养管理相似的荷斯坦奶牛随机分为12组，每组20头。结果显示：高产奶牛血清β-羟丁酸（β-HB）、维生素A（VA）含量及过氧化氢酶（CAT）活性显著高于低产奶牛（P≤0.05）。奶牛围产前期的血清维生素E（VE）、锌（Zn）含量及硫氧还蛋白还原酶（TrxR）活性较低，总超氧化物歧化酶（T-SOD）、谷胱甘肽过氧化物酶（GSH-Px）、CAT活性较高；围产后期的血清葡萄糖（GLU）、VA、VE、硒（Se）含量及T-SOD、GSH-Px活性较低，游离脂肪酸（NEFA）、β-HB、丙二醛（MDA）含量及CAT活性较高；泌乳前期的血清GLU、VA、Se、铜（Cu）含量及总抗氧化能力（T-AOC）、T-SOD、GSH-Px、CAT活性较低，MDA含量较高；泌乳中期的Se含量较低，Zn含量较高；泌乳后期的血清Se、Zn、MDA含量较低，GLU含量与TrxR活性较高；干奶期的血清NEFA、Zn含量较低，GLU含量及GSH-Px活性较高。泌乳阶段与产奶量对奶牛血清Se、Zn含量及T-AOC与GSH-Px、TrxR活性的影响存在显著的互作效应（P＜0.05）。多元回归分析结果表明，在围产后期和泌乳前期，血清抗氧化指标MDA含量与血清营养状况指标NEFA及β-HB含量呈显著正相关（P≤0.05），与VA、VE、Se、Zn、Cu含量呈显著负相关（P≤0.05），而血清其他抗氧化指标T-AOC以及T-SOD、GSH-Px活性与上述血清营养状况指标间的多元回归关系正好与MDA含量相反。综上，泌乳阶段对奶牛血清营养状况指标与抗氧化指标有显著影响，在围产后期与泌乳前期，血清营养状况指标NEFA、β-HB、VA、VE、Se、Zn、Cu含量与抗氧化指标T-AOC及T-SOD、GSH-Px活性和MDA含量间呈显著的多元线性回归关系。
Subjects: Environmental Sciences, Resource Sciences >> Basic Disciplines of Environmental Science and Technology submitted time 2018-11-08 Cooperative journals: 《干旱区研究》
Abstract：依据安康气象局安康站1953—2015年逐日降水量和太阳黑子逐年相对数，利用Mann-Kendall突变检验、Morlet小波分析等方法，对安康地区近63 a降水变化特征及其与太阳黑子相对数关系进行了分析。结果显示：近63 a安康地区年降水量以及夏季降水整体呈增加趋势，增加量分别为 0.99 mm·a-1、1.65 mm·a-1，春季、秋季和冬季降水整体呈下降趋势，减少量分别为0.26 mm·a-1、0.35 mm·a-1、0.06 mm·a-1，降水集中分布在夏季和秋季。年降水距平极值与太阳黑子相对数峰谷值主要存在0~3 a滞后；近63 a安康地区年降水有显著3 a和28 a的变化周期，与太阳黑子相对数的9 a变化周期存在一定差异。
Subjects: Computer Science >> Integration Theory of Computer Science submitted time 2018-04-12 Cooperative journals: 《计算机应用研究》
Abstract： Laser-based ICP-SLAM cannot run directly in the robot operating system, and there is no efficient carrying of computer resources when implementing the algorithm on PC, resulting in waste of resources, while reducing the flexibility of mobile robot system. Build robot operating system on the embedded system, transplant the ICP-SLAM algorithm of the MRPT library into the system, optimize and fixthe CPU occupancy rate of the algorithm, test the function of SLAM by the mobile robot based on the LIDAR. The results show that the grid map thatrobot operating system generated have met the requirements of robot autonomous navigation, and theeffect of SLAM is more intuitive, besides, the system is more flexible, greatly reducecost and hardware configuration requirements. Proved that the optimized algorithm is closer to the practical requirements.
Subjects: Medicine, Pharmacy >> Preclinical Medicine submitted time 2017-12-07 Cooperative journals: 《南方医科大学学报》
Abstract： Objective To establish a two-step pretargeting approach to lymphoma radioimmunoimaging in mice using biotinynaled CD45 monoclonal antibody (McAb) and 188 Re-avidin in a tumor-bearing mouse model. Methods Six Nod-Scid mice bearing lymphoma cell xenograft were randomized to receive either an intravenous injection of 50 μg/200 μL biotinyled CD45 McAb followed 24 h later by an intraperitoneal injection of 3.7 MBq (50 μg/100 μL) 188Re-avidin (two-step pretargeting group), or a single intravenous injection of 3.7 MBq (100 μg/100 μL) 188Re-CD45 McAb (control group). SPECT was performed at 0.5, 1, 6 and 23 h post-injection to characterize 188Re isotope biodistribution. At 24 h pos-injection, the mice were sacrificed for measurement of radioactivity uptake in the tumor and normal tissues and calculation of the tumor-to-non-tumor (T/NT) ratios. Results SPECT showed that the two-step pretargeting method resulted in a low radioactivity in the blood pool during the imaging and a concentrated radioactivity in the liver and spleen. The transplanted tumor began to be displayed at 1 h post-injection and was clearly displayed at 1-6 h; the images were clear even at 23 h. With the two-step pretargeting method, the radioactive uptake at 24 h post-injection were (1.34±0.52)%, (6.77±2.32)%, and (2.81±1.25)% in the tumor, kidney and liver, respectively, with low radioactivity levels in other organs and high tumor/blood and tumor/muscle ratios (4.28±0.82 and 8.00± 0.88, respectively). In the control group, SPECT revealed intense radioactivity in the liver, spleen, and kidneys with obscure display of the tumor; at 20 h, the radioactivity in the blood pool remained high but that in the tumor was low, and the tumor/ blood and tumor/muscle ratios at 24 h were only 0.58±0.06 and 3.21±0.24, respectively. Conclusion Compared with 188Re-CD45 McAb, the two-step pretargeting approach exhibits a good specificity in targeting lymphoma with an increased T/NT ratio in mice and allows early tumor display at 1 h post-injection.
Subjects: Materials Science >> Materials Science (General) submitted time 2016-11-14 Cooperative journals: 《中国腐蚀与防护学报》
Abstract：钛基尺寸稳定性阳极(DSA)在三价铬电镀中的应用已有很多研究，但在六价铬电镀工艺中鲜有研究。本文通过霍尔槽电解，电化学特性，和长期稳定性测试的方法研究DSA(IrO2, Ta2O5)、DSA(IrO2, Pt)阳极和铅锡合金阳极在电镀铬溶液中的性能，并进行对比分析。结果显示钛基DSA阳极真实活性比表面远远大于其几何表面；在镀铬溶液中表现出较低的析氧电位和较好的电催化活性，尤其是DSA(IrO2, Pt)阳极在高电流密度下表现出更好的电催化活性；但是由于溶液中的F-添加剂侵蚀Ti基体使得Ti基涂层阳极在镀铬溶液中的稳定性和寿命均比PbSn合金阳极短。
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