传统SMB、Varicol和Partial-discard工艺分离纯化ECG和EGCG的比较研究

使用B型三带模拟移动床技术,以C18键合硅胶为固定相,乙醇与水(20︰80,V/V)为流动相,分别采取传统SMB工艺、Varicol工艺和Partial-discard工艺分离98%的茶多酚(TP98)。以得到高纯度和高回收率的ECG和EGCG为目标,分别优化柱配置、切换时间、进样流速、冲洗流速。结果表明,采用Varicol工艺能得到纯度为91.33%的ECG,回收率为91.41%;采用Partial-discard工艺能得到纯度为90.12%的EGCG,回收率为97.83%。相对于传统模拟移动床,Varicol工艺具有提高产品纯度和回收率的优点,Partial-discard工艺具有提高收集液浓度和产品纯度的优点。

Narrow-band imaging observation of colorectal lesions using NICE classification to avoid discarding significant lesions

AIM: To assess the risk of failing to detect diminutive and small colorectal cancers with the "resect and discard" policy.METHODS: Patients who received colonoscopy and polypectomy were recruited in the retrospective study. Probable histology of the polyps was predicted by six colonoscopists by the use of NICE classification. The incidence of diminutive and small colorectal cancersand their endoscopic features were assessed. RESULTS: In total, we found 681 cases of diminutive(1-5 mm) lesions in 402 patients and 197 cases of small(6-9 mm) lesions in 151 patients. Based on pathology of the diminutive and small polyps, 105 and 18 were non-neoplastic polyps, 557 and 154 were low-grade adenomas, 18 and 24 were high-grade adenomas or intramucosal/submucosal(SM) scanty invasive carcinomas, 1 and 1 were SM deeply invasive carcinoma, respectively. The endoscopic features of invasive cancer were classified as NICE type 3 endoscopically.CONCLUSION: The risk of failing to detect diminutive and small colorectal invasive cancer with the "resect and discard" strategy might be avoided through the use of narrow-band imaging observation with the NICE classification scheme and magnifying endoscopy.

Experimental evaluation of activated carbon derived from South Africa discard coal for natural gas storage

Lacking in literature is the use of discard coal to produce activated carbon and in its subsequent use in the storage of natural gas. In this study, the characterization and gas storage evaluation of a largely porous activated carbon with large surface area synthesized from discard coal were investigated. Discard coals are waste material generated from coal beneficiation process. In developing the activated carbon, chemical activation route with the use of KOH reagent was applied. The effects of KOH/discard coal weight ratio (1:1, 2.5:1, 4:1), temperature (400-800 ℃) and particle size (0.15-0.25 mm, 0.25-0.5 mm, 0.5-1 mm) on the adsorptive properties of the activated carbon were methodically evaluated and optimized using response surface methodology. The synthesized activated carbon was characterized using BET, SEM/EDS, and XRD. The results showed that for each activation process, the surface area and pore volume of the resulting activated carbon increased with increased temperature and KOH/discard coal weight ratio. The maximum surface area of 1826.41 m2/g, pore volume of 1.252 cm^3/g and pore size of 2.77 nm were obtained at carbonization temperature of 800 ℃ and KOH/discard coal weight ratio of 4:1. Methane and nitrogen adsorption data at high pressure were fitted to Toth isotherm model with a predictive accuracy of about 99%. Adsorption parameters using the Toth model provides useful information in the design of adsorbed natural gas storage system. According to the requirements of adsorbent desired for natural gas storage, it could be stated that the synthesized activated carbon could well be applied for natural gas storage.

Bacterial degradation of coal discard and geologically weathered coal

The biodegradation of coal discard is being intensively studied in South Africa in an effort to develop passive methods for the successful revegetation and rehabilitation of waste dumps, to mitigate pollution, and facilitate mine closure. Bacteria were isolated from slurries of coal tailings and diesel-contaminated soil, screened for coal biodegradation competence, characterized, and the colonization and degradation of coal discard and geologically weathered coal investigated using individual isolates and consortia. Ten novel coal-degrading bacterial strains were isolated and characterized, the gene sequences deposited with GenBank, and the (wild-type) strains deposited at Microbial Culture Collection, India. The results from the present work show that bituminous coal discard and geologically weathered coal is used by these isolates as carbon and energy source. Isolated strains and consortia colonized and degraded both coal substrates. Growth rate of the isolates is faster and stationery phase achieved sooner in minimal medium containing geologically weathered coal. This observation suggests that the oxygen-rich weathered coal is a more friable substrate and thus readily colonised and biodegraded. A reduction in mass of substrate is demonstrated for both individual isolates and consortia. The changes in pH and associated media colouration occurred concomitant with formation of humic acid-like (HS) and fulvic acid-like substances (FS) which is confirmed following analysis of these products by FT-IR spectroscopy. It is concluded that preferential metabolism of alkanes from the coal substrates provided the carbon and energy for bacterial growth and transformation of the substrates to HS and FS.

Sound Absorption Properties of Discarded Feathers/Ethylene Vinyl Acetate Copolymer Thermoplastic Composite Materials

The discarded feathers / ethylene vinyl acetate copolymer( EVA) thermoplastic composite materials was obtained with discarded feathers as reinforced material and EVA powders as matrix material by hot pressing method. Sound absorption properties were studied by changing mass ratio of discarded feathers and EVA,thickness of composite materials,hot pressing pressure and hot pressing temperature. It was found that the sound absorption properties of composite materials were good when the mass ratio of discarded feathers and EVA was 1: 1,thickness of composite materials was 30 mm,hot pressing pressure was 8 MPa,and hot pressing temperature was 80 ℃. Under the optimum conditions,the effect of composite density on sound absorption property was analyzed. In a certain range,the sound absorption property was enhanced with the decrease of the composite density.When the composite density was 0. 1g /cm^3, the maximum absorption coefficient was 0.96. Finally,the capillary theory was used to calculate the maximum sound absorption coefficient of discarded feathers / EVA thermoplastic composite materials. The good agreements of experimental results and calculated results proved the validity of the theoretical models.

Mathematical modeling of induction heating of discard substitution block for billet hot extrusion process

A magnetic and temperature field-coupled mathematical model is proposed to calculate the induction heating process of a discard substitution block for billet hot extrusion process. The mathematical model is validated by comparing simulation results with temperature measurements recorded during physical modeling. Based on systematical analysis of calculation results, a quantitative sawtooth induction power curve was proposed to realize the aim of achieving the best distributed temperature field in the block within the shortest induction time.

Bacterial leaching of discarded copper ores from Yongping, China

The elementary and phase analysis of discarded copper ores from Yongping of China has been performed. The experi- ments of extracting copper from the discarded copper ores were done with the mixed bacteria obtained through a series of enrichment, separation, domestication and combination tests. The results show that in the process of bioleaching, the pH value rises at first and drops gradually. The Eh value keeps rising along with the time and the appropriate Eh value varying between 750 and 800 mV will benefit the bioleaching copper. The high concentration of ferric ions is detrimental to the bioleaching copper. The results of bioleaching copper are good. That is, the copper recovery is 31.8% after 27 days.

How to Comprehensively Utilize the Discarded Fresh Tobacco Leaf ?

This paper aims to explore comprehensive utilization way of discarded fresh tobacco leaf. Based on modern tobacco demands on green,environmental protection and sustainable development,as well as actual situation of biogas production facility in some villages of local tobacco area,this paper selects Longwan Village of Fengshiyan Town as the experimental site and explores the rational way of discarded fresh tobacco leaf biogas fermentation. Results show that cutting and fermentation of discarded fresh tobacco leaf before adding into biogas digester is conductive to improving p H in fermentation process,reducing crust amount,and effectively improving biogas production amount and rate. The study can provide reference for effective processing and rational utilization of discarded fresh tobacco leaf.

The use of demersal trawling discards as a food source for two scavenging seabird species:a case study of an eastern Mediterranean oligotrophic marine ecosystem

Background: The banning of fisheries discards by imposing an obligation to land unwanted catch constitutes a key point of the Common Fishery Policy reform proposed by the European Commission. The effect of such a ban on discards on top marine predators such as seabirds is largely unknown, especially in oligotrophic systems of the Medi?terranean. The current study investigates the presence of scavenging seabirds around fishing trawlers as well as the exploitation of discards produced by bottom trawlers in the eastern Ionian Sea.Methods: On?board observations were randomly conducted in May and December 2014, in order to record the presence and use of fishery discards by two common seabird species, namely, Scopoli's Shearwater(Calonectris diomedea) and the Yellow?legged Gull(Larus michahellis).Results: A total of 3400 seabirds were counted during May of which 2190 individuals were Scopoli's Shearwaters and 1210 were Yellow?legged Gulls. The latter species was the only scavenger observed during winter and in total, 768 individuals were counted. Differences in species abundance in the study area are related to breeding phenology and migratory movements. The number of seabirds attending bottom trawler operations during morning and afternoon hours showed no significant differences for both seabird species. Both scavenging seabirds extensively exploited fishery discards, which were mainly demersal fish, and consumed 70–80% of the total fishery discards biomass; how?ever, they appeared to avoid poisonous species and/or large?sized fish. Yellow?legged Gulls displayed kleptoparasitic behaviour on Scopoli's Shearwater during feeding experiments. The number of such incidents depended on the number of gulls around the fishing vessel, with more than 90% success rates.Conclusions: Considering the average annual biomass of discards estimations and the consumption rate found in this work, 106.1–117.9 t may be offered as a food subsidy to scavenging seabirds in the study area and should support a substantial part of local populations. Our results constitute baseline information on the annual amount of fishery discards and their exploitation rate by seabirds in the Ionian Sea, and suggest further work for a complete understand?ing of the potential impacts of the discards reform bill on seabirds.

THE STUDY OF SABOT-DISCARDING MECHANISM OF GAS-PROPELLED APDS

With the advantages of simpler structure, smaller disturbance and no self-hurt while discarding sabot, the gas-propelled amor-piercing projectile with discarding sabot (APDS) owns its promissing prospect. This paper has studied the gas-filling and ejecting characteristics between the gas chamber iir saber and the environment. A dynamical model describing the sabot-discarding process I?as been established The authors have also given the starling condition and the parting criterion of the parting motion during the sabot-discarding. The mellon of fire gas-propelled APDS has been carefully calculated. Finally, the effect of the gashole area has been analyzed not only on the pressure in the gas chamber near the barrel exit, but also on the sabot-discarding time and distance away from the barrel.

Economical Analysis and Optimization of Recovery Processing Policies about Discarded Product

On the foundation of analyzing the closed loop logistics chain of product with multi-lifecycle, the connotation of environmental value is set forth, recurring to such conceptions as supply chain and value chain.The plotting rules about disassembly tree are discussed in detail. The reachable matrix R of components' disassembly is introduced into distinguishing if disassembly is needed, in combination with disassembly-deciding vector X. Furthermore, the arithmetic of disassembly cost is put forward. And the cost-benefits of components'reusing, materials' recycling, safety disposing are dissertated based on the activity-based costing. Then the 0- 1 goal-programming model on product recovery processing is established, with components' demotion calculated.In addition, takinq the PC's recovery Drocessinq for example, we Dut it into application.

Study on the catch,bycatch and discard of Chinese pelagic longline fisheries in the Atlantic Ocean

Catch,bycatch and discard information is important for the assessment and management of fisheries.Using Chinese pelagic tuna longline observer data from 2010 to 2018,we studied the catch composition in the Chinese pelagic tuna longline fisheries in Atlantic targeting bigeye tuna(Thunnus obesus)and bluefin tuna(Thunnus thynnus),and analyzed the survival status and discard rates of common bycatch species.A total of 55 species,including tunas,billfishes,sharks,sea turtles,cetaceans,seabirds,and other pelagic species,were observed.The results indicated that the catch composition of the Chinese pelagic tuna longline fishery targeting bigeye tuna was significantly different from that targeting bluefin tuna.The annual discard rates of common species decreased over this period.Discard rate by length and discard mortality for common species were varied among species.This is the first study to estimate catch,bycatch,and discard using Chinese pelagic tuna longline observer data in the Atlantic Ocean,which is important for the management of Chinese tuna longline fisheries in Atlantic Ocean.

锂电池回收产出的碳酸锂制备单水氢氧化锂工艺分析与探讨

锂元素的回收是电池回收工艺中的关键步骤,目前一般采用湿法浸出技术将有价元素从锂电池黑粉中转移到溶液中,然后经过除杂净化得到精制的硫酸锂溶液,加入碳酸钠制备成工业级碳酸锂或者碳酸锂粗品,再经精制除杂得到碳酸锂产品返回电池生产过程。随着氢氧化锂市场需求的提高,如何将碳酸锂经济高效地转化为氢氧化锂也成为重要环节。针对电池回收产生的工业级碳酸锂转化为氢氧化锂的工艺过程,详细分析了不同工艺路线的原料选择、工艺过程、产品及副产品产出以及能源消耗等关键因素,通过对比不同工艺路线的优劣势,总结出不同企业状态适用的工艺路线,旨在为优化生产流程、提高回收产业链附加值提供有价值的参考。研究结果将有助于指导电池回收企业在选择氢氧化锂生产工艺时作出决策,同时也为盐湖提锂和矿石提锂产生的碳酸锂生产氢氧化锂提供借鉴。

直径<10 mm结直肠息肉发生高危腺瘤的风险因素分析

目的探讨直径<10 mm结直肠息肉发生高危腺瘤的相关风险因素。方法选取2019年10月至2021年3月解放军总医院第一医学中心和解放军总医院海南医院接受结肠镜检查的患者作为研究对象。根据腺瘤数量和病理特征,将患者分为高危腺瘤组和非高危腺瘤组。分析高危腺瘤发生的风险因素。结果本研究共1267例患者纳入统计分析,其中高危腺瘤组341例(26.9%),非高危腺瘤组926例(73.1%)。高危腺瘤组的年龄(45~<75岁)、男性、饮酒史、吸烟史、频繁食用腌制食品、高盐饮食、慢性病史、结直肠息肉史及最大息肉直径(>5~<10 mm)占比高于非高危腺瘤组(P<0.05)。年龄(45~<75岁)、男性、高盐饮食、偶发肛门坠胀、慢性病史,及最大息肉直径(>5~<10 mm)为高危腺瘤发生的危险因素(OR>1,P<0.05)。结论年龄(45~<75岁)、男性、高盐饮食、偶发肛门坠胀、慢性病史,及最大息肉直径(>5~<10 mm)是直径<10 mm结直肠息肉高危腺瘤发生的影响因素,为内镜医师评估风险及有针对性应用“切除和丢弃策略”提供了基础。

预选抛废技术发展现状

随着我国矿产资源的不断开发与利用,天然高品位矿石资源逐步减少,低品位矿石成为目前我国矿产资源的主要来源,因此,预选抛废成为一个必要的选矿环节。重点阐述了人工拣选抛废、光电选抛废、磁选抛废、重选抛废以及浮选抛废五种抛废技术,并介绍了不同技术在预选抛废时使用的设备和工作原理,指出了各种预选抛废技术的优缺点,为预选抛废技术能进一步工业应用提供了一定借鉴意义。

水火风光多能互补系统联合调度问题两层优化建模方法研究

为解决水火风光多能互补发电系统联合优化复杂问题,提出了一种水火风光多能互补系统联合调度问题两层优化建模和求解方法,上层以余荷均方差和期望均值最小为目标函数对水风光清洁能源打捆进行联合优化,下层以成本经济指标最小为目标函数对火电适配余荷进行优化。以江西省典型春秋季、夏季和冬季江西省的电网负荷以及风电、光电的出力过程为研究对象进行实例分析,采用研究团队提出的DPSA-POA和智能算法混合优化方法进行模型求解,验证了本文所提两层优化建模和求解方法的有效性。并发现了风光可弃情境相比风光完全消纳情景虽然在火电出力上有所提高,但在整体运行费用上有所降低。在以春秋季江西省的电网负荷和风电、光电的出力过程为研究对象进行的实例分析结果显示,火电出力总和提升了5.79%,多能互补系统整体运行费用减少了4.97%;在以夏季江西省的电网负荷和风电、光电的出力过程为研究对象进行的实例分析结果显示,火电出力总和提升了0.32%,多能互补系统整体运行费用减少了1.95%;在以冬季江西省的电网负荷和风电、光电的出力过程为研究对象进行的实例分析结果显示,火电出力总和提升了10.70%,多能互补系统整体运行费用减少了6.78%。该方法为求解水火风光多能互补联合优化复杂问题提供了一种新的思路。

基于YOLOv7网络的废弃塑料瓶颜色智能分选系统研究

由于分拣环境中塑料瓶形状、颜色多样,人工提取的特征往往存在着主观性,可能丢失重要的信息或特征之间的复杂关系,从而导致塑料瓶分类效果差等问题,研究提出了一种基于卷积神经网络的废弃塑料瓶颜色分选系统。收集了市面上常见的塑料瓶,使用工业相机采集图像,使用labelimg进行人工标注制作数据集,通过数据增强来增扩数据集,提高训练模型的鲁棒性。利用YOLOv7卷积神经网络模型进行颜色分类的检测识别,使用喷阀筛选目标颜色的塑料瓶。实验表明,实时检测准确率高达95.7%,具有高度自动化和智能化水平,在回收行业中具有较高的应用价值。

卡瓣数量对尾翼脱壳穿甲弹脱壳过程影响分析

为研究尾翼稳定脱壳穿甲弹(APFSDS)脱壳过程中弹托与弹体之间流场相互作用特性,本文采用FLUENT流体力学计算软件,基于6DOF动网格技术,建立了尾翼稳定脱壳穿甲弹弹托分离三维流场的数值仿真模型,对卡瓣在气动力作用和重力作用下的分离过程进行了模拟,仿真得到了不同时刻卡瓣分离流场以及卡瓣、弹体气动系数随时间变化曲线,并研究了卡瓣数量对分离过程的影响。研究结果表明,在分离初始阶段,弹托前端旋转气流的快速变化会导致弹体阻力突增,弹托阻力突降;中间分离阶段,弹托前脱体激波和弹体的相互作用会导致弹体气动力的波动变化;在弱耦合阶段,卡瓣激波与弹体激波在弹尾处的交汇,会使弹体阻力系数下降。随着弹托卡瓣数量的增加,弹托分离时间减少,弹体气动系数波动程度和弹体气动冲量系数呈减小趋势;4卡瓣弹托在弹托分离过程中对弹体的干扰程度最小。

废弃烟叶分段式提取制备特色烟用香料

采用废弃烟叶为原料,利用常温提取、二次加热提取对烟叶进行分段式提取,得到2种不同的烟叶提取物,并利用气相色谱-质谱(GC-MS)进行化合物成分分析。经常温提取后的烟叶提取物中鉴定出了亚麻酸乙酯、苯甲醇、棕榈酸乙酯等化合物;二次加热后提取其烟草中的特征成分依然存在,但缺少一些醇类、酸类及酯类成分,提取得到更多的烟碱成分。利用2种工艺对废弃烟叶进行分段式提取,得到不同的烟叶提取物,使得提取物具备不同的评吸效果,有助于提高废弃烟叶的差异化利用。