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Enantioselective iridium-catalyzed allylic substitution with a Reformatsky reagent: direct construction of β-stereogenic homoallylic esters

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Science China Chemistry 2024年

作者： Debasis Pal kirana D.Veeranna yuk.Fai Wong P.Andrew Evans Department of Chemistry Queen's University(Canada) Xiangya School of Pharmaceutical Sciences Central South University

The Reformatsky reagent derived from ethyl bromoacetate circumvents the challenge associated with the direct regio-and enantioselective iridium-catalyzed allylic alkylation with an unstabilized aliphatic ester enolate. Notably, this work represents the first example of using a Reformatsky reagent in a metal-allyl reaction, which permits the direct construction of enantioenriched β-stereogenic homoallylic esters without preactivation of the pronucleophile or post-reaction modification of the product(e.g., thermal decarboxylation of a 1,3-dicarbonyl). Moreover, the process allows the coupling of a broad range of sterically and electronically diverse electrophiles bearing aryl, heteroaryl and alkenyl derivatives, including the significantly more challenging alkyl-substituted allylic carbonates. The versatility of the ester product is exemplified by a series of functional group manipulations and the development of a concise and efficient enantioselective total synthesis of the natural product,(+)-descurainolide A. Finally, mechanistic studies indicate that the zinc enolate behaves as a soft nucleophile that undergoes outer-sphere alkylation.

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An omega result for supremum norms of Hecke-eigenforms in the level aspect

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Science China Mathematics 2010年第1期53卷 223-242页

作者： LAU yuk.kam Department of Mathematics The University of Hong KongPokfulam RoadHong KongChina

This note is to remark the large supremum norms of some Hecke-eigenforms of large squarefree levels and nebentypus of small conductors,based on the recent prominent progress by Soundararajan on the extreme central val... 详细信息

关键词： Hecke-eigenforms central values of L-functions

Effects of SARS-CoV-2 infection on incidence and treatment strategies of hepatocellular carcinoma in people with chronic liver disease

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World Journal of Hepatology 2024年第2期16卷 211-228页

作者： Lung-Yi Mak Matthew Shing Hin Chung Xue Li Francisco Tsz Tsun Lai Eric yuk.Fai Wan Celine Sze Ling Chui Franco Wing Tak Cheng Esther Wai Yin Chan Ching Lung Cheung Ivan Chi Ho Au Xi Xiong Wai-kay Seto Man-Fung Yuen Carlos king Ho Wong Ian Chi kei Wong Department of Medicine The University of Hong KongHong KongChina State key Laboratory of Liver Research The University of Hong KongHong KongChina Department of Pharmacology and Pharmacy The University of Hong KongHong KongChina Laboratory of Data Discovery for Health(D24H) Hong Kong Science and Technology ParkHong KongChina Department of Family Medicine and Primary Care The University of Hong KongHong KongChina School of Nursing The University of Hong KongHong KongChina School of Public Health The University of Hong KongHong KongChina Research Department of Practice and Policy University College LondonLondon WC1E 6BTUnited Kingdom Aston School of Pharmacy Aston UniversityBirmingham B47ETUnited Kingdom

BACkGROUND Chronic liver disease(CLD)was associated with adverse clinical outcomes among people with severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)*** To determine the effects of SARS-CoV-2 infection on the incidence and treatment strategy of hepatocellular carcinoma(HCC)among patients with *** A retrospective,territory-wide cohort of CLD patients was identified from an electronic health database in Hong *** with confirmed SARS-CoV-2 infection[coronavirus disease 2019(COVID-19)+CLD]between January 1,2020 and October 25,2022 were identified and matched 1:1 by propensity-score with those without(COVID-19-CLD).Each patient was followed up until death,outcome event,or November 15,*** outcome was incidence of *** outcomes included all-cause mortality,adverse hepatic outcomes,and different treatment strategies to HCC(curative,non-curative treatment,and palliative care).Analyses were further stratified by acute(within 20 d)and post-acute(21 d or beyond)phases of SARS-CoV-2 *** rate ratios(IRRs)were estimated by Poisson regression *** Of 193589 CLD patients(>95%non-cirrhotic)in the cohort,55163 patients with COVID-19+CLD and 55163 patients with COVID-19-CLD were included after 1:1 propensity-score *** 249-d median follow-up,COVID-19+CLD was not associated with increased risk of incident HCC(IRR:1.19,95%CI:0.99-1.42,P=0.06),but higher risks of receiving palliative care for HCC(IRR:1.60,95%CI:1.46-1.75,Pks of allcause mortality(acute:IRR:7.06,95%CI:5.78-8.63,Pk of HCC,they

关键词： SARS-CoV-2 infection Chronic liver disease Long COVID Post-COVID-19 syndrome Cirrhosis Hepatocellular carcinoma

Coefficients of symmetric square L-functions

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Science China Mathematics 2010年第9期53卷 2317-2328页

作者： LAU yuk.kam Department of Mathematics The University of Hong Kong

Let λsym2f(n) be the n-th coefficient in the Dirichlet series of the symmetric square L-function associated with a holomorphic primitive cusp form *** prove Ω± results for λsym2f(n) and evaluate the number of posi... 详细信息

关键词： Fourier coefficients of modular forms B-free numbers

Impacts of wetting-drying cycles on short-term carbon and nitrogen dynamics in Amynthas earthworm casts

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Pedosphere 2021年第3期31卷 423-432页

作者： Michelle Man Suet LAW Derrick yuk.Fo LAI Department of Geography and Resource Management The Chinese University of Hong KongShatinNew TerritoriesHong Kong SARChina Department of Biology Hong Kong Baptist UniversityKowloon TongKowloonHong Kong SARChina Centre for Environmental Policy and Resource Management The Chinese University of Hong KongShatinNew TerritoriesHong Kong SARChina

Effects of earthworm casts on soil nutrient dynamics and their responses to changing moisture availability in subtropical ecosystems remain poorly *** study aimed to examine short-term carbon(C)and nitrogen(N)dynamics and their interactions with wetting-drying cycles in three different structural forms(i.e.,granular,globular,and heap-like)of Amynthas earthworm *** rates of C and N mineralization in the earthworm casts were examined under two different wetting-drying cycles(i.e.,2-d and 4-d wetting intervals)using a rainfall simulation *** three simulated rainfall events,subsamples of the earthworm casts were further incubated for 4 d for the determination of CO2 and N2O *** results of this study indicated that the impacts of wetting-drying cycles on the short-term C and N dynamics were highly variable among the three cast forms,but wetting-drying cycles significantly reduced the cumulative CO2 and N2O fluxes by 62%-83%and 57%-85%,respectively,when compared to the control without being subjected to any rainfall *** C mineralization rates in different cast forms were affected by the amount of organic substrates and N content in casts,which were associated with the food preference and selection of ***,the cumulative N2O fluxes did not differ among the three cast *** wetting and drying of casts not only enhanced aggregate stability by promoting bonds between the cast particles,but also inhibited microbial survival and growth during the prolonged drying period,which together hindered decomposition and *** findings demonstrated that the interactions between the structural forms,aggregate dynamics,and C and N cycling in the earthworm casts were highly complex.

关键词： aggregate stability Cand N cycling earthworm activity earthworm casting greenhouse gas flux mineralization organic matter rainfall simulation

SIMAP500: A novel risk score to identify recipients at higher risk of hepatocellular carcinoma recurrence following liver transplantation

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World Journal of Transplantation 2024年第3期14卷 132-143页

作者： Amr Alnagar Nekisa Zakeri konstantinos koilias Rosemary E Faulkes Rachel Brown Owen Cain M Thamara P R Perera keith J Roberts Rebeca Sanabria-Mateos David C Bartlett yuk.Ting Ma Shivan Sivakumar Shishir Shetty Tahir Shah Bobby V M Dasari Department of HBP and Liver Transplantation Surgery Queen Elizabeth HospitalUniversity Hospitals BirminghamBirmingham B152GWUnited Kingdom Centre for Liver Research Institute of Biomedical ResearchBirmingham B152TTUnited Kingdom Department of Hepatology Queen Elizabeth HospitalUniversity Hospitals BirminghamBirmingham B152GWUnited Kingdom Department of Pathology University Hospitals Birmingham NHS Foundation TrustBirmingham B152GWUnited Kingdom Department of Oncology Queen Elizabeth HospitalUniversity Hospitals of BirminghamBirmingham B152GWUnited Kingdom

BACkGROUND Recurrence of hepatocellular carcinoma(HCC)following liver transplantation(LT)has a devastating influence on recipients’survival;however,the risk of recur-rence is not routinely *** stratification is vital with a long LT waiting time,as that could influence the recurrence despite strict listing *** This study aims to identify predictors of recurrence and develop a novel risk pre-diction score to forecast HCC recurrence following *** A retrospective review of LT for HCC recipients at University Hospitals Bir-mingham between July 2011 and February *** and multivariate analyses were performed to identify recurrence predictors,based on which the novel SIMAP500(satellite nodules,increase in size,microvascular invasion,AFP>500,poor differentiation)risk score was *** 234 LTs for HCC were performed with a median follow-up of 5.3 *** developed in 25 patients(10.7%).On univariate analyses,RETREAT score>3,α-fetoprotein(AFP)at listing 100-500 and>500,bridging,increased tumour size between imaging at the listing time and explant histology,increase in the size of viable tumour between listing and explant,presence of satellite nodules,micro-and macrovascular invasion on explant and poor differentiation of tumours were significantly associated with recurrence,based on which,the SIMAP500 risk score is *** SIMAP500 demonstrated an excellent predictive ability(c-index=0.803)and outper-formed the RETREAT score(c-index=0.73).SIMAP500 is indicative of the time to disease *** SIMAP500 risk score identifies the LT recipients at risk of HCC *** stratification allows patient-centric post-transplant surveillance *** validation of the score is recommended.

关键词： Liver transplantation Hepatocellular carcinoma Recurrence Survival

Food quality and safety in Singapore:microbiology aspects

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Food Quality and Safety 2017年第2期1卷 101-105页

作者： Ye Htut Zwe Hyun Gyun yuk Food Science&Technology Programme Department of ChemistryNational University of Singapore3 Science Drive 3Singapore 117543 Department of Food Science and Technology Korea National University of Transportation61 Daehak-roJeungpyeong-gunChungbukRepublic of Korea27909

BACkGROUND:Singapore’s status as a first world island city-state which relies chiefly on food imports to meet the demand for consumption presents unique challenges in terms of microbial food safety and *** the efforts of the Ministry of Health in Singapore,in conjunction with the Agri-Food&Veterinary Authority of Singapore and the National Environment Agency actively collaborate together to promote safety in Singapore,foodborne diseases are still a major public health ***:The aim of the review was to summarize the various foodborne diseases reported in Singapore in the past few years as well as to give an account of all the currently available microbiological findings indicating safety and quality of poultry,vegetables,fruits,and seafood sold in Singapore.

关键词： Singapore Food safety Food quality Foodborne disease

On the first negative Hecke eigenvalue of an automorphic representation of GL_(2)(A_(Q))

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Science China Mathematics 2021年第11期64卷 2381-2394页

作者： yuk.kam Lau Ming Ho Ng Hengcai Tang Yingnan Wang Department of Mathematics The University of Hong KongHong KongChina Department of Mathematics The Chinese University of Hong KongHong KongChina Institute of Modern Mathematics School of Mathematics and StatisticsHenan UniversityKaifeng 475004China Shenzhen key Laboratory of Advanced Machine Learning and Applications College of Mathematics and StatisticsShenzhen UniversityShenzhen 518060China

Letπbe a self-dual irreducible cuspidal automorphic representation of GL_(2)(A_(Q))with trivial central *** Hecke eigenvalue λπ(n)is a real multiplicative function in *** show that λπ(n)<0 for some n< 详细信息

关键词： automorphic representation Hecke eigenvalue Maass cusp form sign change

Tough and tunable adhesion of hydrogels:experiments and models

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Acta Mechanica Sinica 2017年第3期33卷 543-554页

作者： Teng Zhang Hyunwoo yuk.Shaoting Lin German A.Parada Xuanhe Zhao Department of Mechanical and Aerospace Engineering Syracuse University Soft Active Materials Laboratory Department of Mechanical Engineering Massachusetts Institute of Technology Department of Civil and Environmental Engineering Massachusetts Institute of Technology

As polymer networks infiltrated with water, hydrogels are major constituents of animal and plant bodies and have diverse engineering applications. While natural hydrogels can robustly adhere to other biological materials, such as bonding of tendons and cartilage on bones and adhesive plaques of mussels, it is challenging to achieve such tough adhesions between synthetic hydrogels and engineering materials. Recent experiments show that chemically anchoring long-chain polymer networks of tough synthetic hydrogels on solid surfaces create adhesions tougher than their natural counterparts, but the underlying mechanism has not been well understood. It is also challenging to tune systematically the adhesion of hydrogels on solids. Here, we provide a quantitative understanding of the mechanism for tough adhesions of hydrogels on solid materials via a combination of experiments, theory, and numerical simulations. Using a coupled cohesive-zone and Mullins-effect model validated by experiments, we reveal the interplays of intrinsic work of adhesion, interfacial strength, and energy dissipation in bulk hydrogels in order to achieve tough adhesions. We further show that hydrogel adhesion can be systematically tuned by tailoring the hydrogel geometry and silanization time of solid substrates, corresponding to the control of energy dissipation zone and intrinsic work of adhesion, respectively. The current work further provides a theoretical foundation for rational design of future biocompatible and underwater adhesives.

关键词： Adhesion Hydrogels Soft materials Mullins effect