检索结果-南通市图书馆

Tagetones A and B, new cytotoxic monocyclic diterpenoids from flowers of Tagetes minuta

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Natural Medicines 2017年第7期15卷 546-549页

作者： Sabrin Ragab Mohamed Ibrahim gamal Abd Allah Mohamed Department of Pharmacognosy and Pharmaceutical Chemistry College of Pharmacy Taibah University Al-Madinah Al-Munawarah 30078 Saudi Arabia Department of Natural Products and Alternative Medicine Faculty of Pharmacy King Abdulaziz University Jeddah 21589 Saudi Arabia

Tagetones A(1) and B(2), two new monocyclic diterpenoids were isolated from the n-hexane fraction of fresh flowers of Tagetes minuta L.(Asteraceae). Their structures were established by multiple spectroscopic methods(IR, HR-ESI-MS, and 1D-, and 2D-NMR), in addition to comparison with literature data. Compound 1 showed cytotoxic activity towards MCF7 and A549 cancer cells with IC_(50) values being 4.68 and 4.24 μmol·L^(-1), respectively, compared to doxorubicin(IC_(50) 0.13 and 1.12 μmol·L^(-1), respectively). Compound 2 also exhibited significant activity against HCT116 cancer cells(IC_(50), 6.30 μmol·L^(-1)).

关键词： Tagetes minuta Asteraceae Monocyclic diterpenoids Tagetones Cytotoxic

linear and nonlinear fractional differential equation modified Riemann–Liouville derivatives exact solutions fractional auxiliary sub-equation expansion method Mittag–Leffler function method

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2016年第2期65卷 127-135页

作者： Emad A-B.Abdel-Salam gamal F.Hassan Department of Mathematics Faculty of Science Assiut University New Valley Branch E1-Kharja 72511 Egypt

In this paper, the fractional auxiliary sub-equation expansion method is proposed to solve nonlinear fractional differential equations. To illustrate the effectiveness of the method, we discuss the space-time fractional Kd V equation, the space-time fractional RLW equation, the space-time fractional Boussinesq equation, and the（3＋1）-spacetime fractional ZK equation. The solutions are expressed in terms of fractional hyperbolic and fractional trigonometric functions. These solutions are useful to understand the mechanisms of the complicated nonlinear physical phenomena and fractional differential equations. Among these solutions, some are found for the first time. The analytical solution of homogenous linear FDEs with constant coefficients are obtained by using the series and the Mittag–Leffler function methods. The obtained results recover the well-know solutions when α = 1.

关键词： Solutions to Class of Linear and Nonlinear Fractional Differential Equations

Change of the mode of failure by interface friction and width-to-height ratio of coal specimens

在线全文

学校读者我要写书评

暂无评论

Journal of Rock Mechanics and Geotechnical Engineering 2015年第3期7卷 256-265页

作者： gamal ras.ed Syd S.Peng Department of Mining Engineering West Virginia University

Bumps in coal mines have been recognized as a major hazard for many years. These sudden and violent failures around mine openings have compromised safety, ventilation and access to mine *** studies showed that the violence of coal specimen failure depends on both the interface friction and width-to-height（W/H） ratio of coal specimen. The mode of failure for a uniaxially loaded coal specimen or a coal pillar is a combination of both shear failure along the interface and compressive failure in the coal. The shear failure along the interface triggered the compressive failure in coal. The compressive failure of a coal specimen or a coal pillar can be controlled by changing its W/H ratio. As the W/H ratio increases, the ultimate strength increases. Hence, with a proper combination of interface friction and the W/H ratio of pillar or coal specimen, the mode of failure will change from sudden violent failure which is brittle failure to non-violent failure which is ductile failure. The main objective of this paper is to determine at what W/H ratio and interface friction the mode of failure changes from violent to non-violent. In this research, coal specimens of W/H ratio ranging from 1 to 10 were uniaxially tested under two interface frictions of 0.1 and 0.25, and the results are presented and discussed.

关键词： Bump Burst Coal strength Violent failure Width-to-height(W/H) ratio Interface friction Stressestrain curve

Preliminary rib support requirements for solid coal ribs using a coal pillar rib rating(CPRR)

在线全文

学校读者我要写书评

暂无评论

International Journal of Mining Science and Technology 2021年第1期31卷 15-22页

作者： Khaled Mohamed Mark Van Dyke gamal ras.ed Morgan MSears Robert Kimutis National Institute for Occupational Safety and Health Pittsburgh Mining Research DivisionPittsburghPA 15236USA

Researchers from the National Institute for Occupational Safety and Health(NIOSH)are developing a coal pillar rib rating(CPRR)technique to measure the integrity of coal *** CPRR characterizes the rib composition and evaluates its impact on the inherent stability of the coal *** CPRR utilizes four parameters:rib homogeneity,bedding condition,face cleat orientation with respect to entry direction,and rib *** these parameters are measurable in the field.A rib data collecting procedure and a simple sheet to calculate the CPRR were *** developed CPRR can be used as a rib quality mapping tool in underground coal mines and to determine the potential of local rib instabilities and support requirements associated with overburden *** calculations were conducted for 22 surveyed solid coal ribs,mainly composed of coal *** on this study,the rib performance was classified into four categories.A preliminary minimum primary rib support density(PRSD)line was obtained from these surveyed *** sample cases are presented that illustrate the data collection form and CPRR calculations.

关键词： Coal rib stability Rib support design Coal pillar rib rating Rib quality mapping CPRR Coal classification

A silent network’s resounding success:how mutations of core metabolic genes confer antibiotic resistance

在线全文

学校读者我要写书评

暂无评论

Signal Transduction and Targeted Therapy 2021年第9期6卷 2601-2602页

作者： gamal Wareth Heinrich Neubauer Lisa D.Sprague Friedrich-Loeffler-Institut Institute of Bacterial Infection and ZoonosesJenaGermany Department of Bacteriology Mycology and ImmunologyFaculty of Veterinary MedicineBenha UniversityToukhEgypt

A largely underrated factor in antibiotic resistance is the role of metabolic *** a recent paper published in Science,Lopatkin et al.1 used different in vitro evolution protocols and extensive sequencing data analyses to demonstrate that metabolic mutations develop in response to antibiotic treatment in clinically relevant bacteria(Fig.1).

关键词： resistance network silent

Ensemble Machine Learning to Enhance Q8 Protein Secondary Structure Prediction

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Computers, Materials & Continua 2022年第11期73卷 3951-3967页

作者： Moheb R.Girgis Rofida M.gamal Enas Elgeldawi Computer Science Department Faculty of ScienceMinia University61519MiniaEgypt

Protein structure prediction is one of the most essential objectives practiced by theoretical chemistry and bioinformatics as it is of a vital importance in medicine,biotechnology and *** secondary structure prediction(PSSP)has a significant role in the prediction of protein tertiary structure,as it bridges the gap between the protein primary sequences and tertiary structure *** secondary structures are classified into two categories:3-state category and 8-state *** the 3 states and the 8 states of secondary structures from protein sequences are called the Q3 prediction and the Q8 prediction problems,*** 8 classes of secondary structures reveal more precise structural information for a variety of applications than the 3 classes of secondary structures,however,Q8 prediction has been found to be very challenging,that is why all previous work done in PSSP have focused on Q3 *** this paper,we develop an ensemble Machine Learning(ML)approach for Q8 PSSP to explore the performance of ensemble learning algorithms compared to that of individual ML algorithms in Q8 *** ensemble members considered for constructing the ensemble models are well known classifiers,namely SVM(Support Vector Machines),KNN(K-Nearest Neighbor),DT(Decision Tree),RF(Random Forest),and NB(Naïve Bayes),with two feature extraction techniques,namely LDA(Linear Discriminate Analysis)and PCA(Principal Component Analysis).Experiments have been conducted for evaluating the performance of single models and ensemble models,with PCA and LDA,in Q8 *** novelty of this paper lies in the introduction of ensemble learning in Q8 PSSP *** experimental results confirmed that ensemble ML models are more accurate than individual ML *** also indicated that features extracted by LDA are more effective than those extracted by PCA.

关键词： Protein secondary structure prediction(PSSP) Q3 prediction Q8 prediction ensemble machine leaning boosting bagging

Jellyfish-inspired alginate composite hydrogel filter prepared by macro-micro double bionic strategy for efficient water purification

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Frontiers of Environmental Science & Engineering 2024年第4期18卷 141-157页

作者： Huiting Peng Yan Chen Jiaopan Lin Chelsea Benally Mohamed gamal El-Din Junkai Gao School of Naval Architecture and Marinetime Zhejiang Ocean UniversityZhoushan 316022China Department of Civil and Environmental Engineering University of AlbertaEdmontonAB T6G 1H9Canada

Recently,research on hydrogel materials with a porous structure and superior water absorption capabilities significantly ***,the hydrogel under gravity-driven separation conditions often exhibit an unstable pore structure,poor mechanical properties,and limited *** this end,this work presents a novel approach that combines a macro-micro double bionic strategy with a triple crosslinking method to develop a multifunctional alginate composite hydrogel filter(2%-SA-κCG-PVA-Ca^(2+),2%-SKP-Ca^(2+)for short)with a stable pore structure and superior mechanical properties,which possessed an umbrella-shaped structure resembling that of *** 2%-SKPCa^(2+)filter was synthesized using polyvinyl alcohol(PVA)as a stable structure-directing agent,and sodium alginate(SA)andκ-carrageenan(κ-CG)as polymer *** distinctive umbrellashaped hydrogel of 2%-SKP-Ca^(2+)filter,formed through the triple crosslinking method,overcomes the limitations of unstable pore structure and poor durability seen in hydrogels prepared by traditional crosslinking ***,the utilization of the 2%-SKP-Ca^(2+)filter in water treatment demonstrates its good selective permeability,excellent resistance to fouling,and extended longevity,which enables it to simultaneously achieve the multifunctional water purification and the coating of multi-substrate anti-fouling ***,not only does this research provide an efficient,multifunctional,highly pollution-resistant preparation method for designing a new filter,but it also confirms the application prospect of the macro-micro dual bionic strategy developed in this study in complex water treatment.

关键词： Triple crosslinking method Alginate Umbrella-shaped Jellyfish Water purification

Turbulent flame image classification using Convolutional Neural Networks

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Energy and AI 2022年第4期10卷 87-94页

作者： Rathziel Roncancio Aly El gamal Jay P.Gore School of Mechanical Engineering Purdue UniversityWest LafayetteIN47907USA School of Electrical and Computer Engineering Purdue UniversityWest LafayetteIN 47907USA

Pockets of unburned material in turbulent premixed flames burning CHs,air,and CO_(2) were studied using OH Planar Laser-Induced Fuorescence(PLIF)images to improve current *** flames are ubiquitous in most natural gas air combustors running gas turbines with dry exhaust gas recirculation(EGR)for land-based power *** improvements continue in the charactenization and understanding of turbulent flames with EGR particularly for transient events like ignition and *** and/or islands of unburned material within bumed and unburned turbulent media are some of the features of these *** features reduce the heat release rates and increase the carbon monoxide and hydrocarbons *** present work involves Convolutional Neural Networks(CNN)based dassification of PIF images containing unburned pockets in three turbulent flames with 0%,5%,and 10%CO_(2).The CNN model was constructed using three convolutional layers and two fully connected layers using dropout and weight *** of 94.2%,92.3%and 89.2%were registered for the three flames,*** present approach represents significant computational time savings with respect to conventional image processing methods.

关键词： CNN Flame Neural network Turbulent

Efficacy and Safety of Daclatasvir in Hepatitis C: An Overview

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Clinical and Translational Hepatology 2016年第4期4卷 336-344页

作者： Nesrine gamal Stefano Gitto Pietro Andreone Department of Medical and Surgical Sciences University of Bologna Bologna Italy

Hepatitis C virus (HCV) infection is a growing public health concern,with 184 million people infected *** the past decade,interferon has been the backbone of HCV treatment,even though it remains far from *** latest development of the new direct antivirals has drastically changed the treatment approach for chronic hepatitis C (CHC).Inhibitors of the HCV NS5A region have garnered remarkable interest among treating physicians,due to their high potency and favourable safety *** particular,treatment with daclatasvir (DCV) has yielded high rates of vriologic response in patients infected with genotype (Gt) 1 and Gt 3,when used in combination with other antivirals of a different class,such as *** few data are available for DCV treatment of the other Gts,the results in patients with Gt 2 and Gt 4 infection appear promising,as do those for unique patient ***5A-resistant viral variants can pre-exist or emerge after treatment failure for the HCV NS5A ***,DCV-resistant viral variants continue to be sensitive to interferon and other classes of antivirals such as NS3/4A and NS5B ***,we aimed to provide an overview of the current knowledge about DCV in the treatment of CHC.

关键词： Daclatasvir NS5A inhibitor Hepatitis C Direct antivirals New antiviral therapy