化学“101计划”化学测量学实验课堂提升工作实践

化学测量学实验是教育部化学“101计划”12门核心课程之一,吸收融合了多门化学实验课、具有全新架构的实验课程体系。通过这门课的学习,学生将不但可以了解仪器原理,还能够利用先进的科学仪器进行物质结构、性质和性能的测量,甚至能够设计和搭建仪器。本文主要介绍化学测量学实验课堂提升工作实践,以期更好地促进教师课堂教学实践的交流与借鉴,切实提升国内化学学科的化学测量学实验的教学水平。

Towards Sustainable Grinding of Difficult-to-Cut Alloys-A Holistic Review and Trends

Grinding,a critical precision machining process for difficult-to-cut alloys,has undergone continual technological advancements to improve machining efficiency.However,the sustainability of this process is gaining heightened attention due to significant challenges associated with the substantial specific grinding energy and the extensive heat generated when working with difficult-to-cut alloys,renowned for their exceptional physical and mechanical properties.In response to these challenges,the widespread application of massive coolant in manufacturing industries to dissipate grinding heat has led to complex post-cleaning and disposal processes.This,in turn,has resulted in issues such as large energy consumption,a considerable carbon footprint,and concerns related to worker health and safety,which have become the main factors that restrict the development of grinding technology.This paper provides a holistic review of sustainability in grinding difficult-to-cut alloys,encompassing current trends and future directions.The examination extends to developing grinding technologies explicitly tailored for these alloys,comprehensively evaluating their sustainability performance.Additionally,the exploration delves into innovative sustainable technologies,such as heat pipe/oscillating heat pipe grinding wheels,minimum quantity lubrication,cryogenic cooling,and others.These groundbreaking technologies aim to reduce dependence on hazardous coolants,minimizing energy and resource consumption and carbon emissions associated with coolant-related or subsequent disposal processes.The essence of these technologies lies in their potential to revolutionize traditional grinding practices,presenting environmentally friendly alternatives.Finally,future development trends and research directions are put forward to pursue the current limitation of sustainable grinding for difficult-to-cut alloys.This paper can guide future research and development efforts toward more environmentally friendly grinding operations by understanding the current state of sustainable grinding and identifying emerging trends.

Recent Advances on Polyoxometalate-Based Ion-Conducting Electrolytes for Energy-Related Devices

Solid-state electrolytes have attracted considerable attention in new energyrelated devices due to their high safety and broad application platform.Polyoxometalates(POMs)are a kind of molecular-level cluster compounds with unique structures.In recent years,owing to their abundant physicochemical properties(including high ionic conductivity and reversible redox activity),POMs have shown great potential in becoming a new generation of solid-state electrolytes.In this review,an overview is investigated about how POMs have evolved as ion-conducting materials from basic research to novel solid-state electrolytes in energy devices.First,some expressive POM-based ion-conducting materials in recent years are introduced and classified,mainly inspecting their structural and functional relationship.After that,it is further focused on the application of these ionconducting electrolytes in the fields of proton exchange membranes,supercapacitors,and ion batteries.In addition,some properties of POMs(such as inherent dimension,capable of forming stable hydrogen bonds,and reversible bonding to water molecules)enable these functional POM-based electrolytes to be employed in innovative applications such as ion selection,humidity sensing,and smart materials.Finally,some fundamental recommendations are given on the current opportunities and challenges of POM-based ion-conducting electrolytes.

Effective depolymerization of alkali lignin using an attapulgite-Ce_(0.75)Zr_(0.25)O_(2)(ATP-CZO)-supported cobalt catalyst in ethanol/isopropanol media

Lignin is the world's greatest renewable aromatic biofeedstock,and it has promising applications in high value-added chemical products.Herein,N-Co/ATP-CZO was used as a catalyst for the depolymerization of alkali lignin in ethanol and isopropanol systems,and explored the effects of formic acid(FA)amount,reaction time,reaction temperature and other factors on the depolymerization of alkali lignin.Among them,formic acid serves as both catalytic and in situ-hydrogen donor.Ultimately,the highest yield of bio-oil(59.28%(mass)),including 30.05%(mass)of monomer,was obtained after a reaction of FA to alkali lignin mass ratio of 4 and 240°C for 8 h.Among the monomers,the yield of Guaiacol was the highest(5.94%(mass)),followed by 2-methoxy-4-methylphenol(5.74%(mass)).This study,the modification of attapulgite was carried out to reduce the acidity while enhancing the catalytic activity for depolymerization,and the selection of hydrogen donor was investigated.A feasible pathway for lignin depolymerization research was opened.

Construction and evaluation of an alcohol vapor chamber system

An increasing number of studies demonstrated that alcohol vapor chamber is an effective way to model physical signs of alcohol use disorders. Although researchers are developing different vapor chambers to study chronic alcohol exposure model worldwide, few studies build and modify their own vapor chambers in China.Here, we designed and established an alcohol vapor chamber system for small animals. We described a paradigm showing how to control and monitor alcohol concentration in whole system. The vapor chamber system with several advantages including accommodating up to ten standard mouse cages. Furthermore, the system was tested by evaluating the blood alcohol concentration and neuron injury in mice. Importantly, the alcohol withdrawal after vapor exposure caused motor coordination impairment, anxiolytic-and depression-like behavior. Finally, the Nmethyl-D-aspartate receptor(NMDAR)-mediated glutamatergic transmissions in the medial prefrontal cortex was changed after alcohol vapor exposure-induced behaviors. The frequency and amplitude of spontaneous excitatory postsynaptic currents between control and alcohol groups were not different, suggesting that alcohol exposureinduced behaviors are associated with the change in NMDAR response. Taken together, the new alcohol vapor chamber system was constructed, which would help to research the relationship between the stable alcohol exposure and withdrawal behaviors and to study chronic alcohol exposure-induced disorders in China.

Combined metabolic phenotypes and gene expression profiles revealed the formation of terpene and ester volatiles during white tea withering process

Withering is a critical process to form the unique aroma of high-quality white tea.To study the mechanism underlying aroma changes during the white withering,we herein conducted volatile metabolomics and transcriptomics of the young leaves from the'Fuding Dahaocha'tea cultivar.As the withering time extended,the content of major aroma components increased significantly,score of sensory evaluation and Owuor's flavor index(OFI)also increased.The aromatic substances that accumulated during white tea withering were mainly volatile terpenes and esters.Their change trends were largely consistent with the gene expression of theα-linolenic acid metabolic pathways,while the correlation between the trends in volatiles and the gene expression of the terpenoid biosynthesis pathways was more complex and induced by the jasmonic acid(JA)signaling pathway.Additionally,we also explored the regulation pattern of key genes in the signaling pathway by related transcription factors.Three coexpression networks strongly correlated to the variation of volatile component content during withering were identified by weighted gene coexpression network analysis(WGCNA).Our results provide a new perspective on the processing mechanism and quality improvement of white tea.

Clinical Study of Mesenchymal Stem Cell Treatment for Acute Respiratory Distress Syndrome Induced by Epidemic Influenza A(H7N9) Infection: A Hint for COVID-19 Treatment

2013年,H7N9病毒在哺乳动物宿主之间迅速传播,并具有人与人之间传播的风险。患者表现为重症肺炎、急性呼吸窘迫综合征(acute respiratory distress syndrome,ARDS)和呼吸衰竭。间充质干细胞(mesenchymal stem cell,MSC)移植在病毒性肺炎的治疗中有广阔的前景,并于2013年作为应急性治疗方法来治疗H7N9感染的ARDS。该研究在单中心开展,为开放式临床研究。根据自愿和知情同意的原则,17例H7N9感染的ARDS患者移植同种异体经血来源的MSC作为治疗组,44例H7N9感染的ARDS患者作为对照组。与对照组相比,MSC移植显著降低了ARDS病死率(MSC治疗组和对照组死亡率分别为17.6%和54.5%)。此外,在对4名MSC移植患者进行为期5年的随访中,未发现MSC移植产生有害影响。总体而言,该研究结果表明MSC移植显著提高了H7N9感染的ARDS的存活率,并为开展临床前和临床应用MSC治疗H7N9感染的ARDS的研究提供了理论基础。由于H7N9和新型冠状病毒肺炎(coronavirus disease 2019,COVID-19)临床表现相似(如ARDS和呼吸衰竭),并继发多器官功能障碍,因此基于MSC的疗法可能为COVID-19所致的ARDS患者获益。

Insights into depolymerization pathways and mechanism of alkali lignin over a Ni_(1.2)-ZrO_(2)/WO_(3)/γ-Al_(2)O_(3)catalyst

This study performed catalytic depolymerization of alkali lignin over Ni-based catalysts.Effects of different promoters(Zr and W),Ni loadings,reaction temperatures,and the addition of formic acid and catalyst on lignin conversion and products distribution were all investigated.The result showed that the highest oil yield(40.1%(mass))was obtained at 240℃over Ni_(1.2)/γ-Al_(2)O_(3) promoted by Zr and W species.Quantitative analysis indicates that Zr and W species prefer to lignin depolymerization while Ni active phase prefer to hydrodeoxygenation and hydrogenation.The interconversion of products derived from lignin depolymerization was determined by gas chromatography-mass spectrometer,which demonstrated that phenolic compounds were dominant products in all lignin derived bio-oils,wherein the proportion of vanillin was highest(65.7%)at 180℃,while that of alkyl guaiacols increased with the increase of temperature(from 12.45%at 180℃ to 66.67%at 240℃).Residual lignin obtained after lignin depolymerization was also investigated for detecting differences on functional groups,wherein the disappearing peaks at 1511 cm^(-1)(stretching of aromatic rings),1267,1215 and 1035 cm^(-1)(vibrations of guaiacyl and syringyl units)were detected by Fourier transform infrared spectrometry.Additionally,the higher O/C ratio measured by elemental analysis also confirmed that alkali lignin was depolymerized effectively under mild conditions.

Interannual variability of the spring Wyrtki Jet

Features of the interannual variability of the spring Wyrtki Jet in the tropical Indian Ocean are revealed using observation data and model output.The results show that the jet has signifi cant interannual variation,which has a signifi cant correlation with winter El Niño Modoki index(R=0.62).During spring after an El Niño(La Niña)Modoki event,the Wyrtki Jet has a positive(negative)anomaly,forced by a westerly(easterly)wind anomaly.The result of a linear-continuously stratifi ed model shows that the fi rst two baroclinic modes explain most of the interannual variability of the spring Wyrtki Jet(~70%)and the third to fi fth modes together account for approximately 30%.Surface wind anomalies in the tropical Indian Ocean are related to the Walker circulation anomaly associated with El Niño/La Niña Modoki.The interannual variability of the spring Wyrtki Jet has an evident impact on sea surface salinity transport before the onset phase of the summer monsoon in the Indian Ocean.

Eddy generation mechanism in the eastern South China Sea

Mesoscale eddy generation mechanisms in the eastern South China Sea(ESCS) are investigated using altimetry observations and solutions of a nonlinear, 1?-layer reduced-gravity model. We estimate the relative roles of the wind forcing in the interior South China Sea(SCS) and the remote forcing from the western tropical Pacific(WTP)in eddy generation in the ESCS. Model solutions show that the high-frequency wind in the interior SCS is the primary forcing for eddies, which explains about 54% of the mesoscale eddies generated in the ESCS. Signals from the WTP also play an important role. Wind-driven equatorial signals reach the west coast of Luzon Island through the Sibutu Passage and Mindoro Strait. The reflected Rossby waves from the west coast of Luzon Island propagate westward, become unstable, and turn into eddies. The signals driven by high-frequency wind from the WTP explain about 40% of the mesoscale eddies generated in the ESCS. The high-frequency wind forcing in both the SCS and the WTP is important for eddy generation in the ESCS.

Multi-cycle reconfigurable THz extraordinary optical transmission using chalcogenide metamaterials

Metamaterials composed of metallic antennae arrays are used as they possess extraordinary optical transmission(EOT)in the terahertz(THz)region,whereby a giant forward light propagation can be created using constructive interference of tunneling surface plasmonic waves.However,numerous applications of THz meta-devices demand an active manipula-tion of the THz beam in free space.Although some studies have been carried out to control the EOT for the THz region,few of these are based upon electrical modulation of the EOT phenomenon,and novel strategies are required for act-ively and dynamically reconfigurable EOT meta-devices.In this work,we experimentally present that the EOT resonance can be coupled to optically reconfigurable chalcogenide metamaterials which offers a reversible all-optical control of the THz light.A modulation efficiency of 88%in transmission at 0.85 THz is experimentally observed using the EOT metama-terials,which is composed of a gold(Au)circular aperture array sitting on a non-volatile chalcogenide phase change ma-terial(Ge2Sb2Te5)film.This comes up with a robust and ultrafast reconfigurable EOT over 20 times of switching,excited by a nanosecond pulsed laser.The measured data have a good agreement with finite-element-method numerical simula-tion.This work promises THz modulators with significant on/off ratios and fast speeds.

Interannual variability in the barrier layer and forcing mechanism in the eastern equatorial Indian Ocean and Bay of Bengal

Interannual variability(IAV)in the barrier layer thickness(BLT)and forcing mechanisms in the eastern equatorial Indian Ocean(EEIO)and Bay of Bengal(BoB)are examined using monthly Argo data sets during 2002–2017.The BLT during November–January(NDJ)in the EEIO shows strong IAV,which is associated with the Indian Ocean dipole mode(IOD),with the IOD leading the BLT by two months.During the negative IOD phase,the westerly wind anomalies driving the downwelling Kelvin waves increase the isothermal layer depth(ILD).Moreover,the variability in the mixed layer depth(MLD)is complex.Affected by the Wyrtki jet,the MLD presents negative anomalies west of 85°E and strong positive anomalies between 85°E and 93°E.Therefore,the BLT shows positive anomalies except between 86°E and 92°E in the EEIO.Additionally,the IAV in the BLT during December–February(DJF)in the BoB is also investigated.In the eastern and northeastern BoB,the IAV in the BLT is remotely forced by equatorial zonal wind stress anomalies associated with the El Ni?o-Southern Oscillation(ENSO).In the western BoB,the regional surface wind forcing-related ENSO modulates the BLT variations.

Ureteral reconstruction with decellularized small intestinal submucosa matrix for ureteral stricture: A preliminary report of two cases

Objective:To determine the feasibility of decellularized small intestinal submu-cosa(5IS)matrix in repairing ureteral strictures.Methods:Two patients with ureteral stenoses underwent ureteral reconstruction with SIS ma-trix at the Zhejiang Provincial Corps Hospital of Chinese People's Armed Forces between June 2014 and June 2016.The ureteral stenoses were repaired with a semi-tubular SIS matrix and the postoperative recoveries were observed.Results:Both operations were successfully completed.The average operative time was 90 min and the average length of hospital stay was 15 days.No fevers,incision infections,intestinal obstruction,graft rejection,or other serious complications were noted.After 2 months,ure-teroscopic examinations showed that the surfaces of the original patches were covered by mu-Cosa and there were no apparent stenoses in the lumens.The ureteral stents were replaced every 2 months postoperatively and removed 12 months postoperatively.No infections or uri-nary leakage occurred after removal of the stents.Intravenous urography was performed 6 and 12 months postoperatively.The results showed that the ureters were not obstructed and there was no apparent stenosis at the anastomosis sites.The average follow-up time was>12 months.Long-term follow-up is still ongoing,and computed tomography examin ations of the urinary tract have been conducted in the outpatient department of our hospital 1,3,and 6 months after removal of the double-J stents,suggesting the absence of hydronephrosis.The serum creatinine levels remained stable during the follow-up.Conclusion:SIS matrix reconstruction is a feasible method to repair ureters stenosis.

第11届全国大学生化学实验邀请赛有机化学实验试题解析

介绍了第11届全国大学生化学实验邀请赛有机化学实验操作试题的命题思路,并对实验中存在的问题及成绩进行了分析。

Efficacy and mechanism of methyl salicylate in the enhancement of skin delivery of herbal medicines

Objective: To elucidate the molecular mechanism(s) by which methyl salicylate enhances the skin delivery of herbal ingredients with diverse lipophilicity.Methods: The toxicity of methyl salicylate on skin cell lines was evaluated using the MTT assay. The Franz diffusion cell method was used to measure the permeability enhancing activities of methyl salicylate for five herbal ingredients with a range of lipophilicities. The interaction between methyl salicylate and the stratum corneum(SC) was observed by using an infrared spectroscopy technique. Moreover, the solubilities and SC-vehicle partition coefficient were determined to monitor the impact of methyl salicylate on the drug thermodynamic activities and partition into the SC layer, respectively.Results: Compared with azone(1-dodecylazacycloheptan-2-one), methyl salicylate showed lower toxicity to skin cells in terms of the IC50 values. The in vitro skin permeation studies showed that methyl salicylate could greatly improve the cumulative amounts or steady state flux of the selected model drugs with the exception of osthole, which indicated that methyl salicylate was prone to promote the skin delivery of hydrophilic drugs. The Fourier transform infrared spectroscopy studies revealed that methyl salicylate mainly interacted with SC lipids, leading to the disruption of the orderly arrangement of the SC.In addition, methyl salicylate had no obvious effect on the drug thermodynamic activity and partition into the SC.Conclusion: Methyl salicylate could effectively promote the skin delivery of relatively hydrophilic ingredients in externally used traditional Chinese medicines(TCM) without obvious cytotoxicity.

Therapeutic Efficacy of Complex Decongestive Therapy in the Treatment of Elephantiasis of the Lower Extremities

Objective To evaluate the therapeutic efficacy of complex decongestive therapy in the treatment of elephantiasis of the lower extremities.Methods Seventeen patients with unilateral lower limb elephantiasis were included in the study(5 with primary lymphedema and 12 with secondary lymphedema).All patients were treated with one course(4 weeks)of complex decongestive therapy.Changes inextracellular fluid(ECF),BMI,circumferences,and skin properties including skin stiffness(SF),percent water content(PWC),and trans-epidermal water loss(TEWL)were measured before and after treatment.Results The“elephantiasis-like”appearance of the affected limb was greatly improved after treatment.The ECF,BMI,and circumferences were significantly decreased after treatment(P<0.001)with an average ECF of 2.97±1.82 L,BMI of 1.638±2.647 kg/m^2,and circumference of 6.58±2.79 cm.The values of PWC,TEWL,and SFwere 50.5%±10.6%,18.55±10.2 g/m^2 h,and 0.161±0.176 N,respectively,before treatment and 36.05%±7%,8.3±2.07 g/m^2h,and 0.086±0.038 N,respectively,after treatment,there by showing significant decreases(P<0.05).Conclusion Complex decongestive therapy is effective in the treatment of advanced stages of chronic lymphedema.

Li_(2)ZnTi_(3)O_(8)as the host–separator modifier with efficient polysulfides trapping and fast Li^(+)diffusion for lithium-sulfur batteries

The diffusion and loss of lithium polysulfides(LiPSs)in lithium-sulfur batteries(LSBs)reduce the sulfur utilization rate and the catalytic conversion efficiency of sulfur species,resulting in early battery failure.Li_(2)ZnTi_(3)O_(8)(LZTO),characterized by its stable spinel structure,exhibits high Li+conductivity and holds great potential as an effective adsorbent for LiPSs.This study proposes a collaborative design concept of LZTO host–separator modifier,which offers a complementary and matching approach in the cathode side,effectively addressing the challenges associated with dissolution and inadequate conversion of LiPSs.Density functional theory(DFT)calculation substantiates the pronounced chemical affinity of LZTO towards LiPSs.More importantly,the high efficiency ion transport channels are achieved in separator coating due to the presence of the LZTO particles.Furthermore,the catalytic efficacy of LZTO is validated through meticulous analysis of symmetric batteries and Tafel curves.Consequently,the LZTO host–separator modifier-based cell displays satisfactory rate capability(1449 and 1166 mAh·g^(−1)at 0.1 and 0.5 C)and an impressively capacity(606 mAh·g^(−1)after 500 cycles at 1 C).The coordinated strategy of host–separator modifier is supposed to have wide applications in LSBs.

Constructing electron-blocking grain boundaries in garnet to suppress lithium dendrite growth

Li_(7)La_(3)Zr_(2)O_(12)(LLZO)is considered as a promising solid-state electrolyte due to its high ionic conductivity,wide electrochemical window,and excellent electrochemical stability.However,its application in solid-state lithium metal batteries(SSLMBs)is impeded by the growth of lithium dendrites in LLZO due to some reasons such as its high electronic conductivity.In this study,lithium fluoride(LiF)was introduced into Ta-doped LLZO(LLZTO)to modify its grain boundaries to enhance the performance of SSLMBs.A nanoscale LiF layer was uniformly coated on the LLZTO grains,creating a threedimensional continuous electron-blocking network at the grain boundaries.Benefiting from the electronic insulator LiF and the special structure of the modified LLZTO,the symmetric cells based on LLZO achieved a high critical current density(CCD)of 1.1 mA·cm^(-2)(in capacity-constant mode)and maintained stability over 2000 h at 0.3 mA·cm^(-2).Moreover,the full cells combined with a LiFePO_(4)(LFP)cathode,demonstrated excellent cycling performance,retaining 97.1% of capacity retention after 500 cycles at 0.5 C.Therefore,this work provides a facile and effective approach for preparing a modified electrolyte suitable for high-performance SSLMBs.

How graph convolutions amplify popularity bias for recommendation?

Graphconvolutional networks(GCNs)have become prevalent in recommender system(RS)due to their superiority in modeling collaborative patterns.Although improving the overall accuracy,GCNs unfortunately amplify popularity bias-tail items are less likely to be recommended.This effect prevents the GCN-based RS from making precise and fair recommendations,decreasing the effectiveness of recommender systems in the long run.In this paper,we investigate how graph convolutions amplify the popularity bias in RS.Through theoretical analyses,we identify two fundamental factors:(1)with graph convolution(i.e.,neighborhood aggregation),popular items exert larger influence than tail items on neighbor users,making the users move towards popular items in the representation space;(2)after multiple times of graph convolution,popular items would affect more high-order neighbors and become more influential.The two points make popular items get closer to almost users and thus being recommended more frequently.To rectify this,we propose to estimate the amplified effect of popular nodes on each node's representation,and intervene the effect after each graph convolution.Specifically,we adopt clustering to discover highly-influential nodes and estimate the amplification effect of each node,then remove the effect from the node embeddings at each graph convolution layer.Our method is simple and generic-it can be used in the inference stage to correct existing models rather than training a new model from scratch,and can be applied to various GCN models.We demonstrate our method on two representative GCN backbones LightGCN and UltraGCN,verifying its ability in improving the recommendations of tail items without sacrificing the performance of popular items.Codes are open-sourced^(1)).

A Novel Poly(3-hexylthiophene) Engineered Interface for Electrochemical Monitoring of Ascorbic Acid During the Occurrence of Glutamate-Induced Brain Cytotoxic Edemas

Although neuroelectrochemical sensing technology offers unique benefits for neuroscience research,its application is limited by substantial interference in complex brain environments while ensuring biosafety requirements.In this study,we introduced poly(3-hexylthiophene)(P3HT)and nitrogen-doped multiwalled carbon nanotubes(N-MWCNTs)to construct a composite membrane-modified carbon fiber microelectrode(CFME/P3HT-N-MWCNTs)for ascorbic acid(AA)detection.The microelectrode presented good linearity,selectivity,stability,antifouling,and biocompatibility and exhibited great performance for application in neuroelectrochemical sensing.Subsequently,we applied CFME/P3HT-N-MWCNTs to monitor AA release from in vitro nerve cells,ex vivo brain slices,and in vivo living rat brains and determined that glutamate can induce cell edema and AA release.We also found that glutamate activated the N-methyl-d-aspartic acid receptor,which enhanced Na^(+) and Cl^(−) inflow to induce osmotic stress,resulting in cytotoxic edema and ultimately AA release.This study is the first to observe the process of glutamate-induced brain cytotoxic edema with AA release and to reveal the mechanism.Our work can benefit the application of P3HT in in vivo implant microelectrode construction to monitor neurochemicals,understand the molecular basis of nervous system diseases,and discover certain biomarkers of brain diseases.