Atomically dispersed calcium as solid strong base catalyst with high activity and stability

Solid strong base catalysts are highly attractive for diverse reactions owing to their advantages of neglectable corrosion,facile separation,and environmental friendliness.However,their widespread applications are impeded by basic components aggregation and low stability.In this work,we fabricate single calcium atoms on graphene(denoted as Ca1/G)by use of a redox strategy for the first time,producing solid strong base catalyst with high activity and stability.The precursor Ca(NO_(3))_(2)is first reduced to CaO at 400℃ by the support graphene,forming CaO/G with conventional basic sites,and the subsequent reduction at 850℃results in the generation of Ca1/G with atomically dispersed Ca.Various characterizations reveal that Ca single atoms are anchored on graphene in tetra-coordination(Ca-C_(2)-N_(2))where N is in situ doped from Ca(NO_(3))_(2).The atomically dispersed Ca,along with their anchoring on the support,endow Ca1/G with high activity and stability toward the transesterification reaction of ethylene carbonate with methanol.The turnover frequency value reaches 128.0 h^(-1)on Ca1/G,which is much higher than the traditional counterpart CaO/G and various reported solid strong bases(2.9-46.2 h^(-1)).Moreover,the activity of Ca1/G is well maintained during 5 cycles,while 60%of activity is lost for the conventional analogue CaO/G due to the leaching of Ca.

SYNTHESIS OF DIARYL ETHERS THROUGH PHASE TRANSFER CATALYSIS WITH POTASSIUN FLUORIDE COATED ALUMINA AS A STRONG BASE

Seven diaryl ethers were synthesized with potassium fluoride coated alumina as a strong base and the addition of catalytic amount of PTC. The yield of diaryl ethers with addition of PTC was much higher than that without PTC.A discussion of the catalysis mechanism was given in this paper.

DIRECT TITRATION OF VERY WEAK ACIDS(BASES)IN AQUEOUS SOLUTION WITH STRONG BASES(ACIDS)USING VISUAL END-POINT INDICATION WITHOUT INDICATOR

This paper reports a new method of titration for very weak acids and bases using the appearance of incisions on oscillopolarogram to indicate the end-point.This method has the advantages of rapidity,simplicity,no indicator needed as well as good precision.

Rational fabrication of ordered porous solid strong bases by utilizing the inherent reducibility of metal-organic frameworks

Ordered porous solid strong bases(OPSSBs)have attracted great research interest due to the excellent performance as heterogeneous catalysts in various reactions.The main obstacle for fabricating OPSSBs is the requirement of high temperature to produce strong basicity on ordered porous materials.For example,the temperatures of 600-650℃ are required for the decomposition of base precursor NaNO_(3)to basic sites on mesoporous silica SBA-15 and zeolite Y.Such high decomposition temperatures are energy-intensive and harmful to the structure of supports.Herein,we report the fabrication of OPSSBs by utilizing the redox interaction between base precursor and low-valence metal centers(e.g.,Cr^(3+))in metal-organic frameworks(MOFs).The base precursor NaNO_(3)on MIL-101(Cr)can be converted to basic sites entirely at 300℃,which is quite lower than those of the conventional thermal conversion on SBA-15 and zeolite Y(600-650℃).The exploration on decomposition mechanism reveals that the valence change of Cr^(3+)to Cr^(6+)takes place during the conversion of NaNO_(3)to basic sites.In this way,MOFs-derived base catalysts have been synthesized successfully by the host-guest redox strategy and exhibit high catalytic activity in typical base-catalyzed reactions.

Rapid qualitative and quantitative analysis of strong aroma base liquor based on SPME-MS combined with chemometrics

To objectively classify and evaluate the strong aroma base liquors(SABLs)of different grades,solid-phase microextraction-mass spectrometry(SPME-MS)combined with chemometrics were used.Results showed that SPME-MS combined with a back-propagation artificial neural network(BPANN)method yielded almost the same recognition performance compared to linear discriminant analysis(LDA)in distinguishing different grades of SABL,with 84%recognition rate for the test set.Partial least squares(PLS),successive projection algorithm partial least squares(SPA-PLS)model,and competitive adaptive reweighed samplingpartial least squares(CARS-PLS)were established for the prediction of the four esters in the SABL.CARS-PLS model showed a greater advantage in the quantitative analysis of ethyl acetate,ethyl butyrate,ethyl caproate,and ethyl lactate.These results corroborated the hypothesis that SPME-MS combined with chemometrics can effectively achieve an accurate determination of different grades of SABL and prediction performance of esters.

Effect of Strong Basic Oxide（ Li2O,Na2O,K2O and BaO）on Property of CaO-Based Flux

It is found that strong basic oxides including Li2O,Na2O,K2O and BaO,which are used to replace a part of CaO in CaO-based fluxes,can lower the melting point and the viscosity and enhance the dephosphorizing ability. The mechanism was analysed and the addition of Li2O to CaO based fluxes was recommended.

An Identity-Based Strong Designated Verifier Proxy Signature Scheme

In a strong designated verifier proxy signature scheme, a proxy signer can generate proxy signature on behalf of an original signer, but only the designated verifier can verify the validity of the proxy signature. In this paper, we first define the security requirements for strong designated verifier proxy signature schemes. And then we construct an identity-based strong designated verifier proxy signature scheme. We argue that the proposed scheme satisfies all of the security requirements.

Clinical Evaluation of an Oral Electrolyte Solution Formulated Based on Strong Ion Difference (SID) and Using Propionate as the Organic Anion in the Treatment of Neonatal Diarrheic Calves with Strong Ion Acidosis

Background: It is postulated that the concentrations of the major strong ions (Na, K, and Cl) in oral electrolyte solutions play a major role in clinical efficacy of these solutions for rehydration and corrections of metabolic acid base derangements. Objectives: The purpose of this study was to test prospectively the efficacy of an OES (OESexp) formulated based on concentration of strong ion difference (SID) and propionate in a group of calves with naturally occurring neonatal diarrhea and clinically detectable dehydration and acid base abnormalities. Animals: Ten client owned calves of varying breeds, 2 - 22 days old, presented to a veterinary teaching hospital with a history of naturally occurring acute undifferentiated diarrhea, progressive depression and dehydration for treatment. Methods: Clinical and laboratory parameters were measured pre and post two oral electrolyte treatments to assess efficacy of the experimental OES to correct clinical and clinico pathological parameters. For the clinical trial the calves served as their own controls. For control of safety of medication 4 normal calves were force fed 4 L of OESexp and followed over a 24 hour period. Results: All calves had severe diarrhea and metabolic acidosis. The metabolic acidosis observed in the plasma of these calves and reflected by pH, HCO3- SID and base deficit was corrected significantly towards reference ranges (p < 0.05) with two 2 L feedings 12 hours apart. Dehydration was significantly corrected and all calves were discharged 1 - 3 days post admission. Conclusion and Clinical Importance: The use of SID is a valid approach when formulating oral electrolytes solutions for use in calves with acute diarrhea and metabolic derangement. Sodium propionate is valid substitute for commonly used sodium base equivalents in North America in oral electrolyte solutions.

循证教育视域下新疆学校铸牢中华民族共同体意识教育研究:体系框架与推进路径

研究以循证教育为理论框架,旨在探讨新疆学校如何铸牢中华民族共同体意识。首先,对新疆学校铸牢中华民族共同体意识进行研究,探讨该地区学校在培养学生中华民族共同体意识方面的实践和问题。同时,关注基于循证的思想政治教育研究,以提供理论支持和指导。通过综合运用课程设计、师资培养、数据收集、学校文化建设、家校合作和持续改进等策略,推动中华民族共同体意识教育实践。为新疆学校铸牢中华民族共同体意识的教育提供了循证教育的视角和可行性路径,为相关思想政治教育和实践的发展提供了重要的参考依据。

近千米大直径穿强厚含水层降温管井钻孔设计

制冷降温是深部矿井热害防治的有效技术手段。以核桃峪矿井制冷降温系统建设工程为背景,针对降温管井钻孔深度大,穿过洛河组巨厚强含水层,长距离输送冷媒保冷等技术难题,在分析工程及水文地质条件基础上,确定管井钻孔两次开孔分段设计参数;通过调研管路保冷材料性能,提出复合钢管、静态空气、玻璃微珠增强水泥、钢基复合保温套管四种保冷方法条件下基岩段护壁管设计方案;综合考虑保冷效果、固井可靠性、施工难度等因素,优选工作管采用钢基复合保温套管;并根据套管受力计算,校验护壁管规格参数。工程实施效果表明,井上下降温管始末端温度损失约1℃,可以满足冷媒长距离输送冷量损失要求,对于类似工程具有借鉴价值。

准噶尔盆地中部永进油田超深井井壁稳定钻井液技术

永进油田位于准噶尔盆地中部Ⅲ区块,储层为侏罗系西山窑组,油气埋藏深,地质构造复杂。前期勘探中采用四开制井身结构,随后调整为三开制,二开及以下地层钻进过程中复杂情况频发,井壁稳定性差,钻完井时效低,且前期已完钻井储层污染严重,制约了永进油田勘探与开发进程。为此,基于对该区超深井钻井液技术难点的分析,制定了相应的稳定井壁技术对策,据此针对二开长裸眼井段,研选聚胺强抑制钻井液体系;针对三开复杂地层,研选合成基强封堵钻井液体系。两种钻井液体系经过评价实验与现场应用,均获良好结果。评价实验结果表明,两种钻井液体系均具备较强的抑制性能、封堵性能,针对三开复杂地层的合成基强封堵钻井液体系兼具储层保护性能。两种钻井液体系在永进油田9口井的现场试验应用结果表明:(1)两种钻井液体系辅以现场施工工艺,所形成的超深井井壁稳定钻井液技术切实可行,能够保证应用井在二开长裸眼井段及三开复杂地层钻进过程中井壁稳定,起下钻通畅,中完及完井作业顺利;(2)对比前期完钻的8口井,应用超深井井壁稳定钻井液技术顺利完钻的9口井,井身质量明显提高,钻井、完井时效显著提升(平均钻井周期缩短69.61%,平均完井周期缩短65.29%,平均机械钻速提高80.88%),取得了良好的优快钻井效果;(3)钻井液对储层的污染性小,取得了良好的储层保护效果,应用井完井试油获得稳定高产工业油气流,首次实现了对永进油田油气储量的有效动用。结论认为,井壁稳定钻井液技术在永进油田超深井钻井中的成功应用,为该区块的后续勘探开发提供了有力保障,对其他区块超深井或存在井壁失稳问题井的钻井液技术研究亦有参考意义。

强封堵防塌型水基钻井液体系室内制备及其应用

选取目标区块进行了储层水化行为特性分析,提出了一种强封堵防塌型高性能水基钻井液体系。优选了封堵剂、降滤失剂、抑制剂与润滑剂为关键处理剂,对其流变性、封堵性、抑制性、润滑性、抗温性以及井壁稳定性进行了实验评价,并进行了现场应用测试。结果显示:基浆、3.0%磺化沥青及5%碳酸钙三者组合可实现体系滤失量最低,3%SAP+6%PAH+0.5%HB降滤失效果最佳,6%PEG和5%FH6为抑制剂与润滑剂。配制的水基钻井液体系滤失量几乎为0,页岩滚动回收率为96.99%,可以很好地起到井壁防塌稳定的效用,综合性能与油基钻井液体系相差不大。现场应用测试过程中高温高压失水量低至3.9 mL,钻井固相质量分数仅为5.29%,极压润滑系数显著低于非测试井,验证了该水基钻井液体系的实用性。

强碱性阴离子交换树脂从粗钨酸铵溶液中分离钼的研究

研究了采用ZGA351大孔强碱性阴离子交换树脂从粗钨酸铵溶液中吸附分离钼的工艺方法,考察了树脂型号、料液硫含量、料液陈化时间、料液陈化温度、料液pH值、吸附流速、吸附温度对树脂吸附分离钼效果的影响。结果表明:使用100 mL ZGA351树脂进行动态吸附试验,在料液硫含量为理论量1.1倍、料液陈化时间48 h、料液陈化温度40℃、料液pH值10.0、吸附流速15 mL/h、吸附温度40℃的最优条件下,料液钨损失率仅为0.54%,树脂钼穿透容量为107.77 g/L_(湿树脂),相比目前工业生产应用的HBDM-1树脂钼穿透容量提高了3.15倍。另外,重复试验稳定性良好,ZGA351树脂吸附后得到的纯钨酸铵溶液平均钼钨比为0.88×10^(-4),满足工业生产APT产品用纯钨酸铵溶液钼钨比小于2×10^(-4)的需求。综合而言,采用强碱性阴离子交换树脂从粗钨酸铵溶液中分离钼具有钼穿透容量高、钨损失率低、钨钼分离效率高等优势,为工业化应用提供了一种有效技术参考。

渝西区块龙马溪组强封堵油基钻井液技术研究

渝西区块龙马溪组在水平段钻进过程中因井壁失稳而导致的卡钻、憋顶驱、测井困难等复杂情况频发,研究发现,造成此现象的主要原因是该区块龙马溪组地层微纳米孔、缝发育和钻井液封堵性能不足。因此,在强化现场钻井液封堵性能的基础上优选了钻井液主要处理剂,构建了适用于该区块龙马溪组强封堵油基钻井液体系,室内测试结果表明,经过220 nm和450 nm微孔滤膜时未发生滤失,且综合性能均优于普通钻井液。现场应用表明,龙马溪组水平段钻进过程中未出现井壁失稳问题,与同平台采用常规封堵技术的已钻井相比,平均机械钻速提高8.81 m/h,水平段钻井周期缩短2.79 d,铂金靶体钻遇率100%,创渝西区块深层页岩气井5项钻井指标纪录,强封堵油基钻井液技术能满足该区块钻井工程需要。

“双减”背景下江西高师院校书法教育强基提升策略研究

随着“双减”政策的实施,我国基础教育正面临着深刻的变革。在此背景下,江西高师书法教育迎来了新的挑战与机遇。通过调研江西省师范类高校书法教育现状和统计、分析相关数据后发现:“双减”背景下,师范类高校在书法师资、课程、资源等方面存在不足之处,要从整合与优化课程资源、开展丰富多彩的课后活动、整合信息化教学手段等方面进行改进。

高校“强基计划”选拔中的“体智结合”——基于36所高校“强基计划”体测项目的比较与分析

研究目的:研究36所高校“强基计划”招生简章中的体育加试内容设置及分值占比,为高校“强基计划”选拔中的“体智结合”提供帮助。研究方法:采用文献资料法、数理统计法对36所高校的招生简章、体测项目设置以及评分标准进行比较与分析。研究结果:无故不参加体育加试及体育加试不合格的学生不予录取或取消相关资格的学校有24所;条件相同(文化考试总成绩)下优先录取体育加试成绩优秀的为9所。各校体测项目设置与《国家学生体质健康标准》基本一致(选取其中几项),部分高校还选取了《普通人群体育锻炼标准》中相应的内容;各校体测项目的评分标准与《国家学生体质健康标准》高三群体基本一致;少部分高校由院校自主设置评分标准;调查发现还有35所高校未选取耐力跑作为体测项目;仅8所高校体测项目在4项以上;大部分高校选取身体机能和身体形态以及速度、爆发力等作为体测项目。研究结论:人才选拔应“强基先固本”,健康的体魄应作为高校选拔的必要和前提条件。建议:注重基本体质、体能检测,注重基本运动技术技能加试,注重中学与大学体测项目的衔接,体测项目设置个性化。

基于傅立叶变换中红外光谱技术的浓香型基酒快速检测

为在线监测浓香型白酒酿造过程中不同馏分的质量情况,以摘酒工艺过程中的基酒为研究对象,利用傅立叶变换中红外光谱结合偏最小二乘法建立了基酒中乙醇、乙酸乙酯、丁酸乙酯、己酸乙酯、乳酸乙酯、乙酸、己酸、丁酸8种化合物的快速检测模型。酒精度、乙酸乙酯、乳酸乙酯预测模型的决定系数R2为0.99,己酸乙酯分析模型的R2为0.95,丁酸乙酯、乙酸、己酸检测模型的R2约为0.90,丁酸模型的R2为0.79。8种化合物的红外光谱预测结果与化学值均有良好的线性相关性,并且化合物含量范围越宽,含量分布越均匀,模型的拟合度越好。不同季节温差大会引起基酒红外吸收光谱波动,导致模型检测准确性降低,通过温度补偿全局校正的方法建立的检测模型解决了这一问题,为实现在线自动化摘酒提供了一种可行性方案。

基底原状土置换在超限回填边坡中的运用分析

贵州山区工程建设用地紧张,场地高填深挖现象普遍。以贵州省某县城一弃土场为例,研究分析了坡脚强支护和基底原土置换在超限回填边坡中的应用。通过经济、技术、工期和弃土能力等方面的对比分析,超限回填边坡采用基底原土置换的方案,具有技术可靠、性价比高、工期短等优点,是一种相对科学可行的方案。

面向不平衡数据集的浓香型白酒基酒等级分类研究

为解决基于气相色谱-质谱联用(GC-MS)仪采集的浓香型白酒基酒等级分类中样本不均衡导致分类模型性能下降的问题,提出了一种面向不平衡数据集的浓香型白酒基酒分类研究。该方法首先采用合成少数类过采样技术(SMOTE)对浓香型基酒样品中少数类样本进行扩充,改善样本的不均衡性;然后结合稀疏主成分分析(SPCA)对GC-MS图谱数据进行降维;最后使用深度森林(DF)分类器建立浓香型白酒基酒分类识别模型。结果表明,使用SMOTE算法对基酒数据集进行平衡之后能够有效提高模型分类准确率,所建立的浓香型基酒分类模型正确率达到96.61%,该分类模型的建立对基酒等级分类能起到一定的指导和借鉴作用。

安页2-3HF井强封堵油基钻井液技术研究与应用

针对正安区块页岩气开发过程中龙马溪组井壁失稳频发、掉块严重、卡钻频繁等问题,通过对龙马溪组地层岩性特征研究及井壁失稳机制分析,确定了强化封堵性是研发和改进正安区块油基钻井液技术的关键点。通过关键处理剂中乳化剂和封堵剂的研究,形成了强封堵油基钻井液体系配方,并对其进行性能评价。结果表明:该钻井液具有良好的即时和长效封堵性能,能够有效抑制岩屑的水化分散和膨胀缩径,具有良好的抗岩屑污染能力,岩屑量在20%以内可保持整体性能基本稳定,综合性能远远优于常规油基钻井液,满足正安区块井壁稳定需求。同时,将强封堵油基钻井液在安页2-3HF井现场试用,与已钻邻井相比,三开井段未出现井壁失稳情况,提升了钻井效率,为该区块钻井液优化改进提供了一定的参考。