Ring Enlargement of Alkaloids

The procedure for the ring enlargement of N-heterocycles with the net result of CH2 insertion was successfully carried out with certain alkaloids such as tetrahydroberberine and strychnine.

Single atom Cu-N-C catalysts for the electro-reduction of CO_(2) to CO assessed by rotating ring-disc electrode

The electrochemical CO_(2) reduction reaction(CO_(2)RR) to controllable chemicals is considered as a promising pathway to store intermittent renewable energy. Herein, a set of catalysts based on copper-nitrogendoped carbon xerogel(Cu-N-C) are successfully developed varying the copper amount and the nature of the copper precursor, for the efficient CO_(2)RR. The electrocatalytic performance of Cu-N-C materials is assessed by a rotating ring-disc electrode(RRDE), technique still rarely explored for CO_(2)RR. For comparison, products are also characterized by online gas chromatography in a H-cell. The as-synthesized Cu-NC catalysts are found to be active and highly CO selective at low overpotentials(from -0.6 to -0.8 V vs.RHE) in 0.1 M KHCO_(3), while H_(2) from the competitive water reduction appears at larger overpotentials(-0.9 V vs. RHE). The optimum copper acetate-derived catalyst containing Cu-N_(4) moieties exhibits a CO_(2)-to-CO turnover frequency of 997 h^(-1) at -0.9 V vs. RHE with a H_(2)/CO ratio of 1.8. These results demonstrate that RRDE configuration can be used as a feasible approach for identifying electrolysis products from CO_(2)RR.

Preparation of a highly efficient Pt/USY catalyst for hydrogenation and selective ring-opening reaction of tetralin

Ultrastable Y zeolite（USY）-supported Pt catalyst was prepared by gas-bubbling-assisted membrane reduction. The influence of reaction conditions and the metal and acid sites of catalysts on the catalytic performance of catalyst in hydrogenation and selective ring opening of tetralin, 1,2,3,4-tetrahydronaphthalene（THN）, was studied. It was found that the optimal reaction conditions were at a temperature of 280 °C, hydrogen pressure of 4 MPa, liquid hourly space velocity of 2 h^-1 and H2/THN ratio of 750. Under these optimal conditions, a high conversion of almost 100% was achieved on the 0.3 Pt/USY catalyst. XRD patterns and TEM images revealed that Pt particles were highly dispersed on the USY, favorable to the hydrogenation reaction of tetralin. Ammonia temperature-programmed desorption and Py-IR results indicated that the introduction of Pt can reduce the acid sites of USY, particularly the strong acid sites of USY. Thus, the hydrocracking reaction can be suppressed.

Droplet digital polymerase chain reaction assay for methylated ring finger protein 180 in gastric cancer

BACKGROUND Gastric cancer(GC)is one of the most prevalent malignant tumors that endangers human health.Early diagnosis is essential for improving the prognosis and survival rate of GC patients.Ring finger protein 180(RNF180)is involved in the regulation of cell differentiation,proliferation,apoptosis,and tumorigenesis,and aberrant hypermethylation of CpG islands in the promoter is strongly associated with the occurrence and development of GC.Thus,methylated RNF180 can be used as a potential biomarker for GC diagnosis.AIM To use droplet digital polymerase chain reaction(ddPCR)to quantify the methylation level of the RN180 gene.A reproducible ddPCR assay to detect methylated RNF180 from trace DNA was designed and optimized.METHODS The primer and probe were designed and selected,the conversion time of bisulfite was optimized,the ddPCR system was adjusted by primer concentration,amplification temperature and amplification cycles,and the detection limit of ddPCR was determined.RESULTS The best conversion time for blood DNA was 2 h 10 min,and that for plasma DNA was 2 h 10 min and 2 h 30 min.The results of ddPCR were better when the amplification temperature was 56°C and the number of amplification cycles was 50.Primer concentrations showed little effect on the assay outcome.Therefore,the primer concentration could be adjusted according to the reaction system and DNA input.The assay required at least 0.1 ng of input DNA.CONCLUSION In summary,a ddPCR assay was established to detect methylated RNF180,which is expected to be a new diagnostic biomarker for GC.

Study on reactions of gaseous P_2O_5 with Ca_3(PO_4)_2 and SiO_2 during a rotary kiln process for phosphoric acid production

In a rotary kiln process for phosphoric acid production,the reaction between gaseous phosphorus pentoxide(P_2O_5)and phosphate ore and silica contained in feed balls(the so-called P_2O_5"absorption")not only reduces phosphorous recovery but also generates a large amount of low melting-point side products.The products may give rise to formation of kiln ring,which interferes with kiln operation performance.In this study,the reactions of gaseous P_2O_5with solid calcium phosphate(Ca_3(PO_4)_2),silica(SiO_2)and their mixture,respectively,were investigated via combined chemical analysis and various characterizations comprised of X-ray diffraction(XRD),Fourier-transform infrared(FT-IR)spectroscopy,thermogravimetric analysis and differential scanning calorimeter(TG&DSC),and scanning electron microscopy and energy dispersive spectrometer(SEM&EDS).Attentions were focused on apparent morphology,phase transformation and thermal stability of the products of the P_2O_5"absorption"at different temperatures.The results show that the temperature significantly affected the"absorption".The reaction between pure Ca_3(PO_4)_2 and P_2O_5 occurred at 500°C.Calcium metaphosphate(Ca(PO_3)_2)was the primary product at the temperatures≤900°C with its melting point≤900°C while calcium pyrophosphate(Ca_2P_2O_7)was obtained over 1000°C,which has a melting point≤1200°C.The"absorption"by pure SiO_2 started at 800°C and the most significant reaction occurred at 1000°C with formation of silicon pyrophosphate(SiP_2O_7)product of melting point≤1000°C.Using mixed Ca_3(PO_4)_2and SiO_2as raw material,the"absorption"by Ca_3(PO_4)_2 was enhanced due to existence of silica.At 600–700°C,silica was inert to P_2O_5and thus formed a porous structure in the raw material,which accelerated diffusion of gaseous P_2O_5inside the mixture.At higher temperatures,the combined"absorption"by calcium phosphate and reaction between silicon dioxide and the"absorption"product calcium pyrophosphate,reinforced the"absorption"by the mixture.Besides,it was found that both Ca(PO_3)_2and SiP_2O_7were unstable at high temperatures and would decompose to Ca_2P_2O_7and SiO_2,respectively,at over 1000°C and 1100°C with the release of gaseous P_2O_5at the same time.

Formation of Hybrid Ring Structure of Cyanurate/Isocyanurate in the Reaction be-tween 2,4,6-Tris(4-Phenyl-Phenoxy)-1, 3,5-Triazine and Phenyl Glycidyl Ether

Reaction products of 2,4,6-tris(4-phenyl-phenoxy)-1,3,5-triazine derived from 4-phenylphenol cyanate ester and phenyl glycidyl ether were analyzed. In addition to an isocyanurate compound and an oxazolidone compound which were well known as reaction products of cyanate esters and epoxy resins, compounds with hybrid ring structure of cyanurate/isocyanurate were determined. Gibbs free energies of the compound having hybrid ring structure of cyanurate/isocyanurate with two isocyanurate moiety were found to be lower than that of the compound with cyanurate ring structure through calculations. Calculation data supported the existence of hybrid ring structure of cy-anurate/isocyanurate. It was revealed that isomerization from cyanurate to isocyanurate occurs via hybrid ring structure of cyanurate/isocyanurate in the reaction of aryl cyanurate and epoxy.

A New Approach to Inducing Silicon Tethered Ring-closing Metathesis Reactions

Ring-closing metathesis reactions involving diallyldiphenylsilane and diallyloxydiphenylsilane were successfully performed by using only 0 01 mol or even less of Grubbs' catalyst 1. The effects of reaction parameters, such as solvents, temperature and concentration of the catalyst are discussed.

Syntheses of 2- or 6-Substituted Chromones and Chromone Ring-opening Reaction in Polyphosphoric Acid

In an attempt to find new antitumor agents,a novel class of chromone compounds with a benzimidazole or a benzoxazole ring in positions 2 or 6 were synthesized via condensation in polyphosphoric acid(PPA) by using chromone acids as the starting materials. During the preparation process,it was found that PPA could cleave the chromone ring to produce a ring-opening compound(6). The molar ratio of the chromone compound(5) to the ring-opening compound(6) varied with the change of reaction temperature and time. Based on MTT protocol,the antitumor activity of each of the compounds obtained was evaluated against three human cancer cell lines: KB(oral epidermal),A2780(ovary) and Bel7402(liver). The IC_ 50 varied from 54.7 μmol/L to more than 180 μmol/L.

六元氮杂芳环构建方法及含能材料合成研究

综述了吡啶,哒嗪、嘧啶、吡嗪环、三嗪以及四嗪等六元氮杂芳环骨架构建方法,探讨了相应的六元氮杂芳环环化反应机理,概述了典型含能材料的物化与爆轰性能;重点从合成角度总结了缩合反应与环加成反应在构建六元氮杂芳环结构中的应用,讨论了在相应氮原子中心位点实现氮氧化或氮氨化反应的方式。其中,六元氮杂芳环氮氧化片段的引入主要包括两类途径:一是以氧化剂与氮杂芳环中氮原子中心发生反应,形成N-氧化物片段;另一类是利用环化反应,将相应的氮氧双键等结构转化为N-氧化物片段。附参考文献91篇。

富血小板血浆联合双极射频点阵治疗毛孔粗大的临床效果

目的观察富血小板血浆(PRP)联合双极射频点阵治疗毛孔粗大的临床效果。方法选择2022年5月至2023年5月武汉大学中南医院收治的90例毛孔粗大患者,以随机数字表法将其分为PRP组(30例,PRP治疗)、双极射频点阵组(30例,双极射频点阵治疗)、联合组(30例,PRP联合双极射频点阵治疗)。比较各组临床疗效;比较各组治疗前后皮肤检测仪特征、皮肤生理功能;记录三组不良反应发生情况。结果联合组疗效优于PRP组、双极射频点阵组(P<0.05)。治疗后,三组斑点、红色区、毛孔、皱纹、紫外线色斑、棕色斑、油脂、黑色素、红斑、经皮水分流失评分低于治疗前,且联合组低于PRP组、双极射频点阵组(P<0.05);治疗后,三组纹理、水分评分均高于治疗前,且联合组高于PRP组、双极射频点阵组(P<0.05)。联合组不良反应总发生率低于PRP组、双极射频点阵组(P<0.05)。结论PRP联合双极射频点阵治疗毛孔粗大效果显著,可改善皮肤整体特征,提升皮肤生理功能。

钯催化环加成反应构建中环化合物的研究进展

中环化合物(7—11元环)广泛存在于许多天然产物及药物等功能分子之中,这些分子因具有优异的生物活性及特殊的骨架结构等优点,展现出极其重要的药用价值,如常见的抗癌药物紫杉醇、抗菌药物Spiroxin A等。同时,这类化合物也对化学、医药以及材料等诸多领域产生了深远的影响。但受动力学和热力学因素影响,中环化合物的高效构建依然是一个严峻的挑战。在科研工作者们的不懈努力下,近年来发展出多个新型环加成反应催化体系,其中钯催化环加成反应凭借高效、高选择性和原子经济性等优点在该领域得到了迅猛发展。本文详细介绍了近五年国内外有关钯催化环加成反应构建中环化合物研究的最新进展,旨在为该领域的发展提供一定的帮助。

LCO高效加氢转化关键技术专用催化剂的开发与应用

面向解决催化裂化轻循环油(LCO)出路和富余柴油产能高值化利用的重大需求,以破解LCO加氢转化过程中芳环的加氢、环烷环的开环、烷基侧链的裂化和聚合结焦等关键反应对催化剂活性中心需求不一致的矛盾为切入点,通过创制新型催化材料、优化金属体系并改善制备方法等措施,开发了定向强化开环反应的柴油加氢改质催化剂RIC-3和兼具高开环与高断侧链性能的柴油加氢裂化专用催化剂RHC-100,构建了提高催化剂活性中心有效性、定向性和高效性的活性中心精细调控关键技术平台,形成了以RIC-3和RHC-100为核心、靶向调控多环芳烃加氢开环与裂化反应活性与选择性的催化剂族,可将劣质LCO转化为清洁柴油组分或高辛烷值汽油调合组分,为多环芳烃高效加氢转化技术的开发与应用提供技术支撑。

环氧大豆油多元醇的制备及性能

环氧大豆油(ESO)与生物质小分子山梨醇在催化剂HBF4的作用下发生开环反应制备环氧大豆油多元醇(ESOP)。通过红外光谱确定了ESOP的结构,探究了反应时间、山梨醇与油环氧基团摩尔比、催化剂用量对开环转化率、羟值和黏度的影响,得到制备ESOP的最优工艺条件:反应温度65℃,反应时间4.5 h,山梨醇与油环氧基团摩尔比1∶1,催化剂用量为反应物总质量的1.0%,此条件下ESOP羟值可达184.45 mg/g,开环转化率达到58.8%,黏度3.8 Pa·s,相对分子质量分布适中。流变分析结果表明,ESOP为假塑性流体并且拥有良好的流变性能,热重分析结果表明ESOP的热稳定性优于ESO。

加氢裂化精制段芳烃饱和深度对断侧链和开环反应的影响

通过调节加氢裂化精制段工艺条件参数得到不同芳烃饱和率的精制油,按照烃分子的环结构数目进行分类和数据处理,并结合反应热力学数据研究了芳烃饱和深度对精制段的断侧链和开环反应的影响。结果表明:加氢裂化精制段的断侧链反应以一环烃为主,且芳烃饱和率提高,烷基苯环π键向烷基环己烷σ键的转化,使得反应物形成正碳离子的稳定性降低,这可能是导致断侧链反应平衡常数变小和反应速率变慢的主要原因;低芳烃饱和率下,含硫化合物(噻吩类)等环状烃分子加氢脱除是开环反应的主体,随着芳烃饱和率提高,四环及以上环状烃分子发生开环反应转化为低环数环状烃,而三环及以下环状烃主要发生芳烃饱和反应转化为相同环数的环烷烃。

供-受体环丙烷二酯与苯胺的开环反应

γ-氨基丁酸是许多具有生物活性的化合物的重要结构单元,发展新颖简单的合成这类化合物的方法来具有重要意义。本文以供-受体环丙烷二酯和苯胺为原料,Yb(OTf)_(3)为催化剂,四氢呋喃(THF)为溶剂,30℃下反应4.5 h,以67%~93%收率合成了17个γ-芳氨基-γ-苯基丁酸酯。该合成方法具有反应条件温和和底物普适性广的优点,可用于γ-芳氨基-γ-苯基丁酸酯类化合物的便捷合成。

宫腔镜下子宫内膜息肉切除术联合曼月乐(Mirena)环放置对子宫内膜息肉术后不良反应和复发率的影响

目的探讨宫腔镜下子宫内膜息肉切除术(Trans-Cervical Resection of Polyps,TCRP)联合曼月乐(Mirena)环放置对子宫内膜息肉术后不良反应和复发率的影响。方法方便选取2019年1月—2022年12月在福州经济技术开发区医院收治的102例子宫内膜息肉患者为研究对象,采用随机数表法分为两组,每组51例,均接受TCRP治疗。术后,研究组放置曼月乐环,对照组给予地屈孕酮片,比较两组术前、术后6个月的子宫内膜厚度、月经量、雌孕激素代谢指标、简明女性性功能指数各维度评分,以及不良反应发生情况和复发情况。结果术后6个月,两组子宫内膜厚度、月经失血图评分及腺体、间质雌激素受体、孕激素受体较术前均降低,且研究组低于对照组,差异有统计学意义(P均<0.05)。研究组术后6个月的性生活质量高于对照组,差异有统计学意义(P<0.05)。研究组复发率(1.96%)低于对照组(13.73%),差异有统计学意义(χ^(2)=4.883,P<0.05)。结论TCRP治疗后,放置曼月乐环可减少子宫内膜厚度,改善机体的月经和雌孕激素代谢情况,提高性生活质量和预后质量。

The genetic load for hereditary hearing impairment in Chinese population and its clinical implication

Objective To understand the genetic load in the Chinese population for improvement in diagnosis, prevention and rehabilitation of deafness. Methods DNA samples, immortalized cell lines as well as detailed clinical and audiometric data were collected through a national genetic resources collecting network. Two conventional genetic approaches were used in the studies. Linkage analysis in X chromosome and autosomes with microsatellite markers were performed in large families for gene mapping and positional cloning of novel genes. Candidate gene approach was used for screening the mtDNA 12SrRNA, GJB2 and SLC26A4 mutations in population -based samples. Results A total of 2,572 Chinese hearing loss families or sporadic cases were characterized in the reported studies, including seven X-linked, one Y-linked, 28 large and multiplex autosomal dominant hearing loss families, 607 simplex autosomal recessive hereditary hearing loss families, 100 mitochondrial inheritance families, 147 GJB2 induced hearing loss cases, 230 cases with enlarged vestibular aqueduct (EVA) syndrome, 169 sporadic cases with auditory neuropathy, and 1,283 sporadic sensorineural hearing loss cases. Through linkage analysis or sequence analysis, two X-linked families were found transmitting two novel mutations in the POU3F4 gene, while another X -linked family was mapped onto a novel locus, nominated as AUNX1 (auditory neuropathy, X-linked locus 1). The only Y-linked family was mapped onto the DFNY1 locus(Y-linked locus 1, DFNY1). Eight of the 28 autosomal dominant families were linked to various autosomal loci. In population genetics studies, 2,567 familial cases and sporadic patients were subjected to mutation screening for three common hearing loss genes: mtDNA 12S rRNA 1555G, GJB2 and SLC26A4. The auditory neuropathy cases in our samples were screened for OTOF gene mutations. Conclusions These data show that the Chinese population has a genetic load on hereditary hearing loss. Establishing personalized surveillance and prevention models for hearing loss based on genetic research will provide the opportunity to decrease the prevalence of deafness in the Chinese population.

Epoxidation of Styrene-Isoprene-Styrene Block Copolymer and Research on Its Reaction Mechanism

Styrene-isoprene-styrene（SIS） block copolymer was modified into epoxidized styrene-isoprene-styrene（ESIS） block copolymer with performic acid generated in situ from hydrogen peroxide and formic acid.The structure and property of ESIS were characterized by Fourier transform infrared（FT-IR） spectroscopy,gel permeation chromatography（GPC）,thermogravimetric/differential thermogravimetric（TG/DTG）,melt flow rate（MFR） and dynamic mechanical analysis（DMA）,and the reaction mechanism in the process of epoxidation was analyzed.The results showed that C=C double bonds of 1,4-structure were more active than that of 3,4-structure in polyisoprene chains.With epoxidation reaction proceeding,the whole tendency of molecular weight increased and molecular weight distribution widened,and MFR firstly increased and latterly decreased.The heat resistance of ESIS was superior to that of SIS.When SIS was changed into ESIS with 15.3% of mass fraction of epoxide groups,Tg of polyisoprene chains increased from-45.3 ℃ to 10.9 ℃.In the earlier period of epoxidation,some molecular chains ruptured and new substances with low molecular weight formed.However,in the latter period,crosslinking reaction between molecular chains which was initiated by epoxide groups or C=C double bonds occurred and crosslinked insoluble substances came into being.

RING OPENING POLYMERIZATION OF GLYCOLIDE

The influence of reaction temperature,reaction time, system pressure and catalysts on the re-duced viscosity(ηsp/C)and shear viscosity（ηa）of polyglycollic acid（PGA）is given in thispaper.The adequate polymerization condition of glycolide is selected according to the conditionalexperiments.The heat of polymerization and the activation energy at different conversion levelsare also measured by DSC.

Applications of Cyclometalation Five-Membered Ring Products and Intermediates as Catalytic Agents

The five-membered ring products and intermediates of cyclometalation reactions are very easily synthesized via donation from a hetero atom to a metal atom, which leads to the very high functionality of the product. This functionality is caused by the donation of the hetero atom and various types of metal atoms, halogen atom and other ligands such as alkanes, alkenes, alkynes, Cp, Cp*, aryl groups and heterocyclic compounds. These products have three types of catalytic applications: cyclometalation five-membered ring products as catalysts, cyclometalation five-membered ring intermediates as catalyst agents and cyclometalation five-membered ring intermediates with unconventional substrates and as catalyst actions. Because of the high functionality of these products, the applications of them have been increasing not only as the metathesis in the first and second generations of Hoveyda-Grubbs catalysts but also as in chiral reactions, cross-coupling reactions and polymerization reactions. The above cyclometalation products have been utilized for the production in many industrial fields such as pharmaceuticals, OLEDs, carbon dioxide utilizations, dye-sensitizer solar cells and sensors. We expect that these products would be used for the development of further new industrial products.