苯甲酸、对甲苯胺、乙酰苯胺三组分分离实验教学设计

分离提纯是有机合成中关键的实验步骤,反应后处理这部分的工作内容要占到90%的工作量。为提高学生从混合物中分离目标化合物的实验技能,进一步锻炼学生综合运用萃取、蒸馏、重结晶等纯化实验操作,中南大学化学化工学院有机化学教学组在有机化学实验教学中安排了"三组分混合物分离"实验,面向的学生为医学临床五年制和八年制、化学化工学院的制药工程及应用化学专业。本文详细探讨了该实验的酸、碱分离两种教学方案,对先加酸分离得到的三个组分进行了1H NMR测试。从两个方案的实验教学效果来看,先加酸或先加碱对实验结果没有影响。

苯甲酸、对氨基苯甲酸乙酯、乙酰苯胺三组分分离实验教学设计

为锻炼学生综合运用萃取、蒸馏、重结晶等纯化实验操作,提高学生从混合物中分离并提纯目标化合物的实验技能,中南大学化学化工学院有机化学教学组在有机化学实验教学中安排了“三组分混合物的分离”实验,面向临床医学(五年制、八年制)、药学、生物科学等专业,以及化学化工学院所有专业。鉴于对甲苯胺有毒性,给做实验的学生、实验室教师和指导教师身体带来较大危害,产生的废水对环境也有相当的危害。同时,由于其熔点低,实验室教师每次都要准备冰块,不利于节能省电。尝试使用绿色无毒、熔点较高的对氨基苯甲酸乙酯替代对甲苯胺,可以很好地避免上述两个问题,我们在实验室反复多次做了先加酸或先加碱的两种分离方案后,在有机化学实验B的教学中进行了初步推广,取得了良好的教学效果。

有机化学实验操作失误引导创新——以正溴丁烷制备为例

用正丁醇、溴化钠和硫酸反应制备正溴丁烷是基础有机化学实验教学经常选用的实验,本文设计了以正丁醇、溴化钠和硫酸为原料,使用尾气吸收回流加热装置,先将其中任意两个加热至回流,再瞬间加入第三个原料,详细考察了不同原料加入顺序、不同回流反应时间对正溴丁烷的产率的影响。实验结果可为国内院校开设有机化学实验课程提供实践参考,并启发学生从实验失误中也可以引导实验创新。

Contrasting sources and enrichment mechanisms in lithium-rich salt lakes:A Li-H-O isotopic and geochemical study from northern Tibetan Plateau

Lithium(Li),a crucial mineral resource for modern high-tech industries,is notably abundant in the northern Tibetan Plateau,primarily within lithium-rich salt lakes.However,the exploration and development of these resources are hindered due to an incomplete understanding of their nature and origin.Here we present results from a comprehensive study on the hydrochemical parameters,whole-rock geochemistry,H-O isotopes,and Li concentrations in surface brine,river water,geothermal springs,and associated rocks from two representative lithium-enriched salt lakes,the Laguo Co(LGC)and Cangmu Co(CMC)in Tibet to understand the genetic mechanisms.Our water-salt balance calculations and H-O isotopic analysis reveal that Li in LGC and CMC primarily originates from the Suomei Zangbo(SMZB,~91%)and Donglong Zangbo(DLZB,~75%)rivers,respectively.It is estimated that the LGC and CMC took a minimum of 6.0 ka and 3.0 ka to accumulate their current lithium resources,respectively.The distinct geological characteristics reflect evolutionary differences between the two lakes,suggesting diverse lithium sources and enrichment processes.The high lithium ion concentration and light lithium isotope composition in the SMZB river waters indicate the genetic relationship with lithium-enriched geothermal springs in the Tibetan Plateau.Our results suggest that lithium in the LGC originates from lithium-enriched geothermal springs and is primarily supplied through the small-scale SMZB river.In contrast,the formation and evolution of CMC are influenced by the northern Lunggar rifts,receiving a prolonged and stable input from the DLZB,resulting in high lithium concentrations and isotopic values.The absence of lithium-enriched geothermal springs and the prevalence of silicate rocks in the CMC catchment suggest that lithium may be sourced from the weathering of silicate rocks,such as granitic pegmatite veins containing lithium-rich beryl,widely distributed in the upstream area of DLZB.The forward modeling approach,quantifying the contribution fractions of different reservoirs(atmospheric precipitation,silicate,carbonate,and evaporite),indicates that the distinct lithium concentrations in the mainstream(>1 mg/L)and tributaries(<0.1 mg/L)are positively correlated with the ratio of silicate contributions to carbonate contributions,suggesting that dissolved lithium in river waters primarily originates from the weathering and dissolution of silicate rocks.The distinct sources and enrichment mechanisms of lithium in these two salt lakes are attributed to various evolutionary processes,topographical features,hydrological factors,fundamental geological settings,and tectonic histories,despite their spatial proximity.Furthermore,our study highlights the significant role of rivers in the formation of young salt lakes,in addition to geothermal springs.

Fast mode decomposition for few-mode fiber based on lightweight neural network

In this paper,we present a fast mode decomposition method for few-mode fibers,utilizing a lightweight neural network called MobileNetV3-Light.This method can quickly and accurately predict the amplitude and phase information of different modes,enabling us to fully characterize the optical field without the need for expensive experimental equipment.We train the MobileNetV3-Light using simulated near-field optical field maps,and evaluate its performance using both simulated and reconstructed near-field optical field maps.To validate the effectiveness of this method,we conduct mode decomposition experiments on a few-mode fiber supporting six linear polarization(LP)modes(LP01,LP11e,LP11o,LP21e,LP21o,LP02).The results demonstrate a remarkable average correlation of 0.9995 between our simulated and reconstructed near-field lightfield maps.And the mode decomposition speed is about 6 ms per frame,indicating its powerful real-time processing capability.In addition,the proposed network model is compact,with a size of only 6.5 MB,making it well suited for deployment on portable mobile devices.

Sublayer design and ablation resistance of CVD-TaC alternate coatings with different crystallite morphologies for C/C composites

Tantalum carbon(TaC)alternate coatings with sublayers comprised of different crystallite morphologies were prepared on carbon/carbon composites by chemical vapor deposition.Their ablative behaviors and defending mechanisms were both investigated.The specimen with the sublayer composed of columnar crystals exhibited a better ablation resistance due to the toughness enhancement induced by the lami-nated structure.However,the mechanical denudation of the sample only containing acicular crystals and the coating spallation caused by superfluous gaseous products of the sample with the sublayer composed of nanocrystals both indicate their inferior anti-ablation properties.It is believed that the results will be helpful for the structural design and practical application of chemical vapor deposition(CVD)alternate coatings.

Therapeutic evaluation of lumbar tender point deep massage for chronic non-specific low back pain

OBJECTIVE:To observe the therapeutic effect of lumbar tender point deep tissue massage plus lumbar traction on chronic non-specific low back pain using change in pressure pain threshold,muscle hardness and pain intensity as indices.METHODS:We randomly divided 64 patients into a treatment group(32 cases) and a control group(32 cases).Two drop-outs occurred in each group.Patients in the treatment group received tender point deep tissue massage plus lumbar traction and patients in the control group received lumbar traction,alone.We used a tissue hardness meter/algometer and visual analog scale(VAS) to assess the pressure pain threshold,muscle hardness and pain intensity.RESULTS:Following treatment,we obtained the following results in the treatment and control groups,respectively:the pressure pain threshold difference was 1.5±0.8 and 1.1±0.7;the muscle hardness difference was 4.2±1.6 and 3.5±1.3;and the VAS score difference was 1.9±0.9 and 1.4±0.8.Compared to the control group,the treatment group had higher pressure pain threshold(t=2.09,P<0.05),and lower muscle hardness(t=2.05,P<0.05) and pain intensity(t=2.46,P<0.05).CONCLUSION:Lumbar tender point deep tissue massage combined with lumbar traction produced better improvement in pressure pain threshold,muscle hardness and pain intensity in patients with chronic non-specific low back pain than with lumbar traction alone.

Lacustrine Shale Oil Resource Potential of Es3L Sub-Member of Bonan Sag, Bohai Bay Basin, Eastern China

Following shale gas, shale oil has become another highlight in unconventional hydrocarbon exploration and development. A large amount of shale oil has been produced from a host of marine shale in North America in recent years. In China, lacustrine shale, as the main source rock of conventional oil and gas, should also have abundant oil retained in place. In this study, geochemical and geologic characteristics of lacustrine shale from Es3L sub-member in Bonan sag were characterized by using total organic carbon（TOC）, Rock-Eval pyrolysis, X-ray diffraction, and ？log R method. The results show that the Es3L sub-member shale have TOC contents ranging from 0.5 wt.% to 9.3 wt.%, with an average of 2.9 wt.%. The organic matter is predominantly Type I kerogen, with minor amounts of Type II1 kerogen. The temperature of maximum yield of pyrolysate（Tmax） values ranges from 424 to 447 ℃, with an average of 440 ℃, and vitrinite reflectance（Ro%） ranges from 0.7% to 0.9%, indicating most of shales are thermally mature. The dominant minerals of Es3L shale in Bonan sag are carbonates（including calcite and dolomite）, averaging 51.82 wt.%, and the second minerals are clay（mostly are montmorillonite-illite-mixed layer and illite） and quartz, averaging about 18 wt.%. Finally, its shale oil resources were evaluated by using the volumetric method, and the evaluation result shows that the shale oil resource is up to 5.94 billion tons, and mostly Class I resource. Therefore, the exploration of the lacustrine shale oil of Es3L in Bonan sag should be strengthened.

High efficiency ternary organic solar cells enabled by compatible dual-donor strategy with planar conjugated structures

Ternary organic solar cells(OSCs) have received extensive attention for improving the power conversion efficiency(PCE) of organic photovoltaics(OPVs). In this work, a novel donor material(ECTBD) consisting of benzodithiophene(BDT) central electron donor unit was developed and synthesized. The small molecular donor has the same central unit as PM6. The addition of ECTBD into PM6:Y6 system could improve the morphology of active blend layer. In addition, ECTBD showed good morphologically compatibility when blending with PM6:Y6 host, resulting in the improvement of fill factor and current density. As a result, the ternary devices based on PM6:ECTBD:Y6 ternary system achieved a highest PCE of 16.51% with fill factor of 76.24%, which was much higher than that of the binary devices(15.7%). Overall, this work provided an effective strategy to fabricate highly efficient ternary organic solar cells through design of the novel small molecular donor as the third component.

Ternary organic solar cells:Improved optical and morphological properties allow an enhanced efficiency

The power co nversion efficiency(PCE)of OFQx-T:PC_(71)BM blend films reaches 7.59%.On this basis,ternary organic solar cells(OSCs)were fabricated with ITIC or PTB7-Th as the third component.The ternary OSCs with 50 wt%ITIC in acceptors exhibits an enhanced efficiency,from 7.59%to 8.17%.Also,the PCE of ternary OSCs with 50 wt%PTB7-Th in donors achieves 8.72%,which is 13%higher than that of binary OSCs.The PCE improvement of two ternary OSCs is mainly due to the increase of short-circuit current density(J_(SC)),which can be attributed to the complementary absorption spectra and improved film morphology.This work suggests that the selection of an appropriate third component plays a critical role in improving the PCE of ternary OSCs.