bluuebunny/crossref_metadata_2025_split huggingface dataset:
N‐Heterocyclic Silylenes as Ligands in Transition Metal Carbonyl Chemistry: Nature of Their Bonding and Supposed Innocence
Authors: Krahfuß Mirjam J. , Nitsch Jörn , Bickelhaupt F. Matthias , Marder Todd B. , Radius Udo 
Published: March 2020

AbstractA study on the reactivity of the N‐heterocyclic silylene Dipp2NHSi (1,3‐bis(diisopropylphenyl)‐1,3‐diaza‐2‐silacyclopent‐4‐en‐2‐yliden) with the transition metal complexes [Ni(CO)4], [M(CO)6] (M=Cr, Mo, W), [Mn(CO)5(Br)] and [(η5‐C5H5)Fe(CO)2(I)] is reported. We demonstrate that N‐heterocyclic silylenes, the higher homologues of the now ubiquitous NHC ligands, show a remarkably different behavior in coordination chemistry compared to NHC ligands. Calculations on the electronic features of these ligands revealed significant differences in the frontier orbital region which lead to some peculiarities of the coordination chemistry of silylenes, as demonstrated by the synthesis of the dinuclear, NHSi‐bridged complex [{Ni(CO)2(μ‐Dipp2NHSi)}2] (2), complexes [M(CO)5(Dipp2NHSi)] (M=Cr 3, Mo 4, W 5), [Mn(CO)3(Dipp2NHSi)2(Br)] (9) and [(η5‐C5H5)Fe(CO)2(Dipp2NHSi‐I)] (10). DFT calculations on several model systems [Ni(L)], [Ni(CO)3(L)], and [W(CO)5(L)] (L=NHC, NHSi) reveal that carbenes are typically the much better donor ligands with a larger intrinsic strength of the metal–ligand bond. The decrease going from the carbene to the silylene ligand is mainly caused by favorable electrostatic contributions for the NHC ligand to the total bond strength, whereas the orbital interactions were often found to be higher for the silylene complexes. Furthermore, we have demonstrated that the contribution of σ‐ and π‐interaction depends significantly on the system under investigation. The σ‐interaction is often much weaker for the NHSi ligand compared to NHC but, interestingly, the π‐interaction prevails for many NHSi complexes. For the carbonyl complexes, the NHSi ligand is the better σ‐donor ligand, and contributions of π‐symmetry play only a minor role for the NHC and NHSi co‐ligands.
Variable‐Length Ester‐Based Staples for α‐Helical Peptides by Using A Double Thiol‐ene Reaction
Authors: Paterson Danielle L. , Flanagan Jack U. , Shepherd Peter R. , Harris Paul W. R. , Brimble Margaret A. 
Published: March 2020

AbstractA novel peptide stapling method effected by a double thiol‐ene reaction between two cysteine residues and a divinyl diester to access stapled peptides with enhanced cell permeability is reported. This diverse chemical tool kit provides facile access to stapled peptides with varying bridge lengths. Stapled Axin mimetics were synthesised by using this stapling method resulting in improved α‐helicity relative to the unstapled peptide. Cell penetrating stapled analogues of the SIGK peptide that targets the protein–protein interaction hotspot of Gβγ proteins were also synthesised that exhibited a moderate increase in α‐helicity and were cell permeable. This chemoselective peptide stapling method is highly amenable as a facile method to easily modify synthetic α‐helical peptides to target intracellular proteins.
Prebiotically Plausible Organocatalysts Enabling a Selective Photoredox α‐Alkylation of Aldehydes on the Early Earth
Authors: Closs Anna C. , Fuks Elina , Bechtel Maximilian , Trapp Oliver 
Published: March 2020

AbstractOrganocatalysis is a powerful approach to extend and (enantio‐) selectively modify molecular structures. Adapting this concept to the Early Earth scenario offers a promising solution to explain their evolution into a complex homochiral world. Herein, we present a class of imidazolidine‐4‐thione organocatalysts, easily accessible from simple molecules available on an Early Earth under highly plausible prebiotic reaction conditions. These imidazolidine‐4‐thiones are readily formed from mixtures of aldehydes or ketones in presence of ammonia, cyanides and hydrogen sulfide in high selectivity and distinct preference for individual compounds of the resulting catalyst library. These organocatalysts enable the enantioselective α‐alkylation of aldehydes under prebiotic conditions and show activities that correlate with the selectivity of their formation. Furthermore, the crystallization of single catalysts as conglomerates opens the pathway for symmetry breaking.
Development of Therapeutic Gramicidin S Analogues Bearing Plastic β,γ‐Diamino Acids
Authors: Guan Qinkun , Chen Kaisen , Chen Qiang , Hu Jianguo , Cheng Keguang , Hu Chengfei , Zhu Jibao , Jin Yi , Miclet Emeric , Alezra Valérie , Wan Yang 
Published: March 2020

AbstractGramicidin S (GS), one of the most widely investigated antimicrobial peptides (AMPs), is known for its robust antimicrobial activity. However, it is restricted to topical application due to undesired hemolytic activity. With the aim of obtaining nontoxic GS analogues, we describe herein a molecular approach in which the native GS β‐turn region is replaced by synthetic β,γ‐diamino acids (β,γ‐DiAAs). Four β,γ‐DiAA diastereomers were employed to mimic the β‐turn structure to afford GS analogues GS3–6, which exhibit diminished hemolytic activity. A comparative structural study demonstrates that the (βR,γS)‐DiAA is the most‐stable β‐turn mimic. To further improve the therapeutic index (e. g., high antibacterial activity and low hemolytic activity) and to extend the molecular diversity, GS5 and GS6 were used as structural scaffolds to introduce additional hydrophobic or hydrophilic groups. We show that GS6K, GS6F and GS display comparable antibacterial activity, and GS6K and GS6F have significantly decreased toxicity. Moreover, antibacterial mechanism studies suggest that GS6K kills bacteria mainly through the disruption of the membrane.
A blockchain‐based traceable group loan system
Authors: Li Jinjiang , Zheng Zhihua , Li Zhi , Niu Ziyu , Qin Hong , Wang Hao 
Published: March 2020

SummaryDifficulties in financing and low utilization of funds are main financial problems that plague the development of small and medium‐sized enterprises. The key to solving this problem lies in opening up the social data circulation between enterprises. It is a good solution for enterprises with frequent data interactions to form groups. Using group loans, the borrowing enterprises could solve the funding difficulties and the loan enterprises could improve the utilization rate of funds. In this article, we construct a group loan system based on blockchain technology, which can promote the free flow of funds among enterprises in the group. We combine the blockchain with the trusted execution environment to realize the automatic determination of loan conditions and realize the automatic execution of smart contracts. We also use the linkable group signature technology to ensure the traceability of loan users while protecting the anonymity. In addition, we use homomorphic encryption technology to make the statement confidential and computable.
Volatility Study of Amino Acids by Knudsen Effusion with QCM Mass Loss Detection
Authors: Štejfa Vojtěch , Pokorný Václav , Miranda Carlos F. P. , Fernandes Óscar O. P. , Santos Luís M. N. B. F. 
Published: March 2020

AbstractThis work presents a new Knudsen effusion apparatus employing continuous monitoring of sample deposition using a quartz‐crystal microbalance sensor with internal calibration by gravimetric determination of the sample mass loss. The apparatus was tested with anthracene and 1,3,5‐triphenylbenzene and subsequently used for the study of sublimation behavior of several proteinogenic amino acids. Their low volatility and thermal instability strongly limit possibilities of studying their sublimation behavior and available literature data. The results presented in this work are unique in their temperature range and low uncertainty required for benchmarking theoretical studies of sublimation behavior of molecular crystals. The possibility of dimerization in the gas phase that would invalidate the effusion experiments is addressed and disproved by theoretical calculations. The enthalpy of sublimation of each amino acid is analyzed based on the contributions in two hypothetical sublimation paths involving the proton transfer in the solid and in the gas phase.
Corporate social responsibility, stakeholder engagement, and universities: New evidence from the Italian scenario
Authors: Aversano Natalia , Di Carlo Ferdinando , Sannino Giuseppe , Tartaglia Polcini Paolo , Lombardi Rosa 
Published: March 2020

AbstractThis paper aims at analyzing the connection among the corporate social responsibility (CSR), stakeholder engagement and universities, proposing the analysis of universities' financial reporting to draft their third mission and social impact. Particularly, our analysis is based on the sensitivity demonstrated by the Italian public universities in terms of transparency on issues of social responsibility with reference to the heritage assets' reporting and disclosure. We used a qualitative methodology, adopting the content analysis to collect data from the financial reporting of all Italian public universities. Our findings show as heritage assets represent the strategic area for the assessment of the third mission and social impact by the Italian universities even if the level of their disclosure seems low. Evidence of our paper is directed to support the academic community, practitioners, and policymakers proposing a new theoretical and practical advance of the CSR and stakeholders engagement' studies.
The Permissibility of Deception in Riskier Research
Authors: Wendler David 
Published: March 2020

ABSTRACTThe use of deception is typically prohibited in studies that pose greater than minimal risk overall. This approach prevents researchers from using deception to conceal significant risks or to deceive participants about the purpose, potential benefits, or other aspects of a study that are relevant to deciding whether to accept such risks. Yet this approach also mistakenly blocks appropriate research. In particular, it keeps researchers from using deception in studies that pose greater than minimal risk, even when participants are informed accurately about the risks and other aspects of the study that are relevant to deciding whether to participate. Rather than prohibiting deception when the overall study poses greater than minimal risk, policies should prohibit deception when the aspect of the study about which participants are deceived poses greater than minimal risk.
Study on the structural forms of the key strata in the overburden of a stope during periodic weighting and the reasonable working resistance of the support
Authors: Zhu Cheng , Yuan Yong , Yuan Chao‐feng , Liu Fu‐quan , Chen Zhong‐shun , Wang Sheng‐zhi 
Published: March 2020

AbstractMany mines often passively select supports with a higher yield load to avoid the occurrence of support crushing and roof falling during periodic weighting. This method is not conducive to improving production efficiency or reducing mining costs, but it can ensure safe mining. An effective method for overcoming these problems is to determine the reasonable working resistance of the support according to the structural forms of the key strata in the overburden of the stope during periodic weighting. In this paper, comprehensive theoretical analysis, numerical simulation, and field observation were applied to study the discrimination of the key stratum structure (KSS) during periodic weighting and the calculation method of the support load. First, the KSS that affects the periodic weighting of the stope was classified. The “twice discrimination method” was proposed for determining the breaking form of the key strata and the articulated form of the broken blocks. On this basis, the spacing condition that determines whether adjacent key strata interact was analyzed. The discriminant conditions for synergistic breaking between the first subordinate key stratum (SKS1) and the upper key stratum were derived for the cases in which the SKS1 periodically breaks in the form of a cantilever beam, a voussoir beam, and a step beam. These conditions provide the basis for distinguishing the KSS in the overburden of the stope. In addition, mechanical models of the roof structure during periodic weighting were established, and general formulas for calculating the support loads of stopes with a single‐key‐stratum influence structure and a multikey‐stratum influence structure were presented. Finally, five fully mechanized coal faces with various mining conditions in China were considered for engineering verification. The results of this study demonstrate that the proposed method for determining the reasonable working resistance of the support is consistent with the field practice. The research results can provide a reference for roof control and support selection of stopes.
Role of platelet infiltration as independent prognostic marker for gastric adenocarcinomas
Authors: Wang Jing , Zhang Miao , Zhou Ting , Zhao Shengmei , Su Zhenguo , Liu Xiangdong 
Published: March 2020

AbstractBackgroundIn recent years, the relationship between malignant tumors and platelets has been paid more attention. The increase of platelets is an independent risk factor for the poor prognosis of some malignant tumors.MethodsThis study retrospectively analyzed the clinical and pathological data of 114 patients with initial gastric cancer from August 2005 to August 2018 in Shandong Provincial Hospital. Single‐factor and multifactor survival analysis were used to evaluate the effect of platelet elevation on postoperative survival. The gastric cancer tissues of the Jinan Central Hospital and its matched paracancerous tissues were collected. The expression of platelets in tissues was detected by immunofluorescence technique. Different numbers of platelets were co‐cultured with MKN‐45 cells, CCK‐8 assay and transwell assay were performed, and the expression of epithelial‐mesenchymal transition‐related proteins was detected.ResultsPlatelet count was independent factors affecting prognosis. The stratified analysis showed that there was a statistically significant difference in the 5‐year survival rate between the platelet‐increase group and the normal platelet group in the TNM stages I‐II. The expression of platelets in gastric cancer tissues was higher than that in adjacent tissues. The results of CCK‐8 and transwell showed that platelets significantly enhanced the proliferation and metastasis capability of MKN‐45 cells in a concentration‐dependent manner. After co‐culture, the expression level of E‐cadherin protein in MKN‐45 cells decreased, and the protein expression levels of N‐cadherin, vimentin, and VEGFA increased.ConclusionPlatelet elevation is closely related to the occurrence, development, and metastasis of gastric cancer, and platelet count can be used as a prognostic indicator for malignant tumors.
Uses of cyclohexan‐1,3‐dione for the synthesis of tetrahydrochromeno[3,4‐c]chromen derivatives with anti‐tumor activities
Authors: Mohareb Rafat M. , Megally Abdo Nadia Y. , Gamaan Marwa S. 
Published: March 2020

AbstractCyclohexan‐1,3‐dione (1) was used as the key starting material, which reacted with salicylaldehyde (2) and either malononitrile (3a) or ethyl cyanoacetate (3b) in ethanol containing a catalytic amount of triethylamine to give the 3,4,7,12b‐tetrahydrochromeno[3,4‐c]chromen‐1‐one derivatives 5a,b. The latter compounds underwent Gewald's thiophene synthesis through the reaction with either malononitrile or ethyl cyanoacetate to give compounds 6a‐d, respectively. On the other hand, compound 5a was used for the synthesis of annulated chromeno[3,4‐c]chromen derivatives through its reaction with different chemical reagents. The synthesized compounds were evaluated against the six cancer cell lines A549, HT‐29, MKN‐45, U87MG, SMMC‐7721, and H460 using the standard MTT assay in vitro, with foretinib as the positive control, many compounds expressed high inhibitions. The most active compounds 5b, 6b, 6d, 7, 9b, 11a, 11b, 13, 17, 18b, 20b, 21b, 21e, and 21f were selected for inhibition of five tyrosine kinases and some selected compounds for Pim‐1 kinase inhibition. The results showed that compounds 6b, 6d, 11a, 13, 17, 20b, and 21e were the most potent compounds with the tyrosine kinases and compounds 6d, 11a, 20b, and 21e were the most potent inhibitors of Pim‐1 kinase.
Predicting the Outcome of Transcatheter Arterial Embolization Therapy for Unresectable Hepatocellular Carcinoma Based on Radiomics of Preoperative Multiparameter MRI
Authors: Sun Yuejun , Bai Honglin , Xia Wei , Wang Dong , Zhou Bo , Zhao Xingyu , Yang Guowei , Xu Ligang , Zhang Wei , Liu Pingping , Xu Jiacheng , Meng Siyu , Liu Rong , Gao Xin 
Published: March 2020

BackgroundIn unresectable hepatocellular carcinoma (HCC), methods to predict patients at increased risk of progression are required.PurposeTo investigate the feasibility of radiomics model in predicting early progression of unresectable HCC after transcatheter arterial chemoembolization (TACE) therapy using preoperative multiparametric magnetic resonance imaging (MP‐MRI).Study TypeRetrospective.PopulationA total of 84 patients with BCLC B stage HCC from one medical center. According to the modified response evaluation criteria in solid tumors, patients who progressed at 6 months after TACE therapy were assigned as the progressive disease (PD) group (n = 32). Patients whose MRI was performed on four devices were divided into a training cohort (n = 67). Patients whose MRI was performed on other than the previous four devices were used as the testing set (n = 17).Field Strength/Sequence3.0T, 1.5T axial T2‐weighted imaging (T2WI), diffusion‐weighted imaging (DWI, b = 0, 500 s/mm2), and apparent diffusion coefficient (ADC)AssessmentPD was confirmed via imaging studies with MRI. Risk factors, including age, alpha fetoprotein (AFP), size, and radiomic‐related features of PD were assessed. In addition, the discrimination ability of each radiomics signature was tested on an independent testing set.Statistical TestsThe area under the receiver‐operator characteristic (ROC) curve (AUC) was used to evaluate the predictive accuracy of the radiomic signature in both the training and testing sets. The results indicated that the MP‐MRI model achieved the greatest benefit.ResultsIn the testing set, the model based on DWI features presented an AUC of (b = 0, 0.786; b = 500, 0.729), followed by T2WI features (0.729) and ADC (0.714). The AUC of the MP‐MRI signature was increased to 0.800 compared to any single MRI signature. The multivariate logistic analysis identified the radiomics signature as independent parameters of PD, while clinical information such as age, AFP, size, etc., had no significance in the PD group.Data ConclusionPreoperative MP‐MRI has the potential to predict the outcome of TACE therapy for unresectable HCC. In addition, these image features may be complementary to the current staging systems of HCC patients.Level of Evidence2.Technical Efficacy Stage3. J. Magn. Reson. Imaging 2020;52:1083–1090.
COVID‐19 epidemic: Disease characteristics in children
Authors: She Jiatong , Liu Lanqin , Liu Wenjun 
Published: March 2020

AbstractIn mid‐December 2019, a disease caused by infection with severe acute respiratory syndrome coronavirus‐2, which began in Wuhan, China, has spread throughout the country and many countries around the world. The number of children with coronavirus disease‐2019 (COVID‐19) has also increased significantly. Although information regarding the epidemiology of COVID‐19 in children has accumulated, relevant comprehensive reports are lacking. The present article reviews the epidemiological characteristics of COVID‐19 in children.
Occult HCV and occult HBV coinfection in Iranian human immunodeficiency virus‐infected individuals
Authors: Jamshidi Sogol , Bokharaei‐Salim Farah , Esghaei Maryam , Bastani Mohammad‐Navid , Garshasbi Saba , Chavoshpour Sara , Dehghani‐Dehej Farzaneh , Fakhim Shahin , Khanaliha Khadijeh 
Published: March 2020

AbstractThe presence of hepatitis C virus (HCV) genome in liver biopsy or peripheral blood mononuclear cell (PBMC) specimens in the absence of detectable HCV‐RNA in plasma of the people with or without anti‐HCV antibodies has defined as occult HCV infection (OCI), whereas occult hepatitis B virus infection (OBI) is detection of hepatitis B virus (HBV) genome in the absence of traceable hepatitis B surface antigen in the plasma samples of patients. The purpose of this study is to determine the presence of OBI and OCI in human immunodeficiency virus (HIV)‐infected individuals. In this cross‐sectional research, 190 Iranian HIV‐infected individuals were enrolled from September 2015 to February 2019. All participants were tested regarding various serological markers for HCV and HBV infections. Viral RNA and DNA were extracted from plasma and PBMC specimens, and the presence of HCV‐RNA in plasma and PBMC samples was tested using reverse transcriptase‐nested polymerase chain reaction (PCR), HBV viral load was determined in plasma samples using COBAS TaqMan 48 Kit, and also the presence of the HBV‐DNA in PBMC samples was tested by real‐time PCR. In this study, the prevalence of OBI and OCI in HIV‐infected individuals was 3.1% and 11.4%, respectively. The genotypes of HCV in the patients with OCI were as follows: 57.1% were infected with subtype 3a, 35.7% were infected with subtype 1a, and 7.1% was infected with subtype 1b. It is noteworthy that in this study, two patients (1.1%) had OCI/OBI coinfections. The present study revealed that 1.1% of Iranian HIV‐infected individuals had OBI and OCI at the same time. Therefore, it seems that designing prospective surveys to determine the presence of this coinfection in HIV‐infected individuals is informative.
Analysis of heart injury laboratory parameters in 273 COVID‐19 patients in one hospital in Wuhan, China
Authors: Han Huan , Xie Linlin , Liu Rui , Yang Jie , Liu Fang , Wu Kailang , Chen Lang , Hou Wei , Feng Yong , Zhu Chengliang 
Published: March 2020

AbstractAn outbreak of severe acute respiratory syndrome novel coronavirus (SARS‐CoV‐2) epidemic spreads rapidly worldwide. SARS‐CoV‐2 infection caused mildly to seriously and fatally respiratory, enteric, cardiovascular, and neurological diseases. In this study, we detected and analyzed the main laboratory indicators related to heart injury, creatine kinase isoenzyme‐MB (CK‐MB), myohemoglobin (MYO), cardiac troponin I (ultra‐TnI), and N‐terminal pro‐brain natriuretic peptide (NT‐proBNP), in 273 patients with COVID‐19 and investigated the correlation between heart injury and severity of the disease. It was found that higher concentration in venous blood of CK‐MB, MYO, ultra‐TnI, and NT‐proBNP were associated with the severity and case fatality rate of COVID‐19. Careful monitoring of the myocardiac enzyme profiles is of great importance in reducing the complications and mortality in patients with COVID‐19.