Synergistic Effect of Starch on the Antibacterial Activity of Honey

Laid Boukraa,Karim Amara 한국식품영양과학회 2008 Journal of medicinal food Vol.11 No.1

The role of amylase present in honey in enhancing its antibacterial activity was evaluated in the presence andabsence of starch. Two strains of pathogenic bacteria have been used: Staphylococcus aureusand Escherichia coli. For S. au-reus, the minimum inhibitory concentration (MIC) for the three varieties of honey tested without starch was 11%, 24%, and29% (vol/vol), respectively. When starch was added with honey to the media the MIC obtained was 5%, 19%, and 25%(vol/vol), respectively. For E. coli, the MIC for the three varieties without starch was 23%, 28%, and 25% (vol/vol), respec-tively. When starch was added with honey to media, the MIC was 19%, 26%, and 23% (vol/vol), respectively. It is specu-lated that the amylase present in honey hydrolyzed the starch chains to randomly produce dextrin and maltose and that thisincreased the osmotic effect of the media, which consequently increased the antibacterial activity.

A Parametric Study on the Elastic Lateral-Torsional-Vertical Buckling Capacity of Horizontally Curved Twin I-Girder Systems Considering the Effect of Curvature and Girder Spacing

Lay Allen Nicolas,Albert Surla,Jong Sup Park,Kee Se Lee,Young Jong Kang 한국방재학회 2015 한국방재학회 학술발표대회논문집 Vol.14 No.-

This parametric study investigates the effect of significant parameters on the elastic global lateral torsional buckling capacity of horizontally curved twin I-girder systems. Included are the effect of curvature and the effect of girder spacing. Twin I-girder systems analyzed in this study are those which are interconnected by intermediate cross frames and are subjected to uniform moment. The finite element analysis software, ABAQUS, is used to model the horizontally curved twin I-girder system and conduct the buckling analysis. To see the significant effect of curvature and girder spacing, the results from the finite element analysis of horizontally curved twin I-girder systems are compared to the results of a closed form solution for straight twin I-girder systems. The findings of this parametric study will be shown using illustrative figures and tabulated data and conclusions are made.

Additive Action of Royal Jelly and Honey Against Staphylococcus aureus

Laid Boukraa,Abdellatif Niar,Hama Benbarek,Mokhtar Benhanifia 한국식품영양과학회 2008 Journal of medicinal food Vol.11 No.1

Four varieties of honey and one variety of freshly reaped royal jelly (RJ) were used to evaluate their additiveaction against Staphylococcus aureus(ATCC 29523). In a first step honey and RJ were used separately to determine theirminimum inhibitory concentration (MIC) against the tested strain. In a second step, lower concentrations of honey than theMIC were added to lower concentrations of RJ than the MIC and then incorporated into media to determine the minimum ad-ditive inhibitory concentration. When tested separately, the MIC of the four varieties of honey ranged between 20% and 21%(vol/vol), and that of RJ was 2% (vol/vol). When used jointly, all honey varieties had a more than 50% decrease in MIC with1% (vol/vol) RJ. A strong linear correlation was noted between the MIC decrease of all varieties of honey and RJ.

Green Air Transport System: An Overview of Issues, Strategies and Challenges

Lay Eng Teoh,Hooi Ling Khoo 대한토목학회 2016 KSCE Journal of Civil Engineering Vol.20 No.3

Globally, the environmental sustainability of air transport is receiving greater concern nowadays owing to its critical impact on climate change. This paper provides an overview of the environmental (green) issues in relation to aviation activities, focusing on aircraft emission and noise. The influential factors of the respective green issue (including aircraft characteristics and operations) as well as the relevant mitigation strategies, ranges from the technological innovation, operational strategy, fleet planning to the policies, rules and regulations are discussed accordingly. Besides, mathematical modeling, statistical analysis and survey which emerge to be the main methodologies adopted to alleviate the green issues are also discussed in detailed. Concisely, the literatures reveal that there is no single strategy or approach that can be implemented to ease the green issue. Thus, integrated effort and commitment from the relevant parties are required to yield a greener system. By identifying the literature gaps and also the potential rooms for improvement under uncertainty, it is anticipated that this paper could provide some useful insights to the relevant parties in charting the effective strategies to attain a green air transport system.

School-Based Counseling in Singapore

Lay See Yeo,Boon-ooi Lee 한국상담학회 2014 Journal of Asia Pacific counseling Vol.4 No.2

School-based counseling in Singapore, a city-state in Southeast Asia, had its nascent beginnings in the 1960s. Over the years, it has steadily evolved to become a credible and accessible mainstay of school mental health support that is increasingly relevant and sensitive to the social and emotional needs of students in the education system. This article provides an overview of the key milestones in the development of school-based counseling in Singapore. It also describes the roles assumed by school counselors and discusses the current concerns and challenges they face. It concludes by presenting the aspirations of school counselors and charting future directions.

Sahara Honey Shows Higher Potency Against Pseudomonas aeruginosa Compared to North Algerian Types of Honey

Laid Boukraa,Abdellatif Niar 한국식품영양과학회 2007 Journal of medicinal food Vol.10 No.4

Six varieties of honey from different regions in Algeria were used to determine their potency againstPseudomonas aeruginosa. Four varieties originated from northern Algeria, and two from the Sahara. Three types of mediawere used. On nutrient agar the minimum inhibitory concentration (MIC) of the four northern varieties ranged between 30%(vol/vol) and 31% (vol/vol), while the MIC of the Sahara varieties was 11% (vol/vol) and 14% (vol/vol). On King A agar theMIC of the four northern varieties ranged from 25% (vol/vol) to 31% (vol/vol), whereas the MIC of the two varieties of Sa-hara honey was 12% (vol/vol) and 15% (vol/vol). On nutrient broth the MIC of the northern varieties ranged from 10%(vol/vol) to 21% (vol/vol), whereas the MIC of the two varieties of Sahara honey was 9% (vol/vol). The botanic flora of Sa-hara is known in Algeria for its medicinal uses, and thus the higher potency of the Sahara honey is most probably due to an-tibacterial substances in its plant derivates. These findings suggest that Sahara honey could be used for managing wounds andburns, which are mostly infected by P. aeruginosa.

Evaluation of anti-inflammatory effect of traditional medicinal plants, Gynura segetum

Lay-Jing Seow,Hooi-Kheng Beh,Amirin Sadikun,Mohd. Zaini Asmawi 셀메드 세포교정의약학회 2014 TANG Vol.4 No.1

Gynura segetum, family Asteraceae is a cultivated species and can be found growing in the tropical regions of Indonesia and Malaysia. The plant is known for its use for the treatment of cancer, inflammation, diabetes, hypertension and skin afflictions. In the current study, anti-inflammatory effect of Gynura segetum leaf has been investigated. The present study investigated the in vivo anti-inflammatory effect of Gynura segetum leaf by using hen’s egg test-chorioallantoic membrane (HET-CAM) assay. Different solvent extract of Gynura segetum leaf were tested, the most active methanol extract was further fractionated and tested. Among the extracts tested, the methanol extract showed a significant good anti-inflammatory effect (76.8% inhibition at 50 µg/disc) on the HET-CAM assay as compared with the anti-inflammatory drug indomethacin (82.1% inhibition). However, the fractionated sample exhibited a significantly lower activity in comparison to crude methanol extract. The results demonstrated that Gynura segetum leaf displayed remarkable anti-inflammatory effects, which support the folkloric uses of this plant for treatment of inflammation.

Inelastic Buckling Capacity of Beams Considering Load Height Effect, Stepped Flanges, and Compact or Noncompact Sections

Lay Allen Nicolas,박종섭 한국강구조학회 2016 International Journal of Steel Structures Vol.16 No.4

This study aims to investigate the effects of load height, stepped beam configuration and section compactness on the inelastic lateral buckling strength of doubly and singly stepped I-beams. To study the effects of load height, the loads are situated at three points: at the center of the top flange, at the shear center and at the center of the bottom flange. To check for the effect of stepped beam configuration, beams were stepped either at both top and bottom flanges or at top flange only. Meanwhile, to investigate the effects of section compactness, two sections are analyzed: one section with compact flanges and web and another section with non-compact flanges and a compact web. The loadings are limited to those having an inflection point of zero. To also check the effect of steps, stepped parameters α, β and γ are varied. The buckling strengths of the beams investigated are obtained by conducting nonlinear analysis using the finite element program, ABAQUS. In conducting the nonlinear analysis, the residual stresses and geometric imperfections are taken into consideration to clearly simulate the inelastic behavior of the beams. The results of the analysis would then determine if the location of the loads, configuration of stepped flanges and compactness of flanges have significant effect on the inelastic buckling strength of the stepped beams.

Theoretical buckling analysis of inhomogeneous plates under various thermal gradients and boundary conditions

Laid Lekouara,Belgacem Mamen,Abdelhakim Bouhadra,Abderahmane Menasria,Kouider Halim Benrahou,Abdelouahed Tounsi,Mohammed A. Al-Osta 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.86 No.4

This study investigates the theoretical thermal buckling analyses of thick porous rectangular functionally graded (FG) plates with different geometrical boundary conditions resting on a Winkler-Pasternak elastic foundation using a new higherorder shear deformation theory (HSDT). This new theory has only four unknowns and involves indeterminate integral variables in which no shear correction factor is required. The variation of material properties across the plate’s thickness is considered continuous and varied following a simple power law as a function of volume fractions of the constituents. The effect of porosity with two different types of distribution is also included. The current formulation considers the Von Karman nonlinearity, and the stability equations are developed using the virtual works principle. The thermal gradients are involved and assumed to change across the FG plate’s thickness according to nonlinear, linear, and uniform distributions. The accuracy of the newly proposed theory has been validated by comparing the present results with the results obtained from the previously published theories. The effects of porosity, boundary conditions, foundation parameters, power index, plate aspect ratio, and side-to-thickness ratio on the critical buckling temperature are studied and discussed in detail.

Key amino acid residues conferring enhanced enzyme activity at cold temperatures in an Antarctic polyextremophilic β-galactosidase

Laye, Victoria J.,Karan, Ram,Kim, Jong-Myoung,Pecher, Wolf T.,DasSarma, Priya,DasSarma, Shiladitya National Academy of Sciences 2017 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.114 No.47

<P><B>Significance</B></P><P>Combining comparative genomics, mutagenesis, kinetic analysis, and molecular modeling provides a powerful way to explore and understand the structure and function of proteins under extreme and potentially astrobiological conditions. Alignment of closely related cold-active and mesophilic β-galactosidase enzymes from halophilic Archaea, followed by mutagenesis and kinetic analysis, demonstrates the importance of specific amino acid residues in temperature-dependent catalytic activity, while molecular modeling provides a structural framework for their mechanism of action. Such an interdisciplinary approach shows how a very small fraction of conserved residues that are divergent from mesophilic homologs are key to enhancing catalytic activity at cold temperatures and underscores the power of combining genomics and genetics with biochemistry and structural biology for understanding polyextremophilic enzyme function.</P><P>The Antarctic microorganism <I>Halorubrum lacusprofundi</I> harbors a model polyextremophilic β-galactosidase that functions in cold, hypersaline conditions. Six amino acid residues potentially important for cold activity were identified by comparative genomics and substituted with evolutionarily conserved residues (N251D, A263S, I299L, F387L, I476V, and V482L) in closely related homologs from mesophilic haloarchaea. Using a homology model, four residues (N251, A263, I299, and F387) were located in the TIM barrel around the active site in domain A, and two residues (I476 and V482) were within coiled or β-sheet regions in domain B distant to the active site. Site-directed mutagenesis was performed by partial gene synthesis, and enzymes were overproduced from the cold-inducible <I>csp</I>D2 promoter in the genetically tractable Haloarchaeon, <I>Halobacterium</I> sp. NRC-1. Purified enzymes were characterized by steady-state kinetic analysis at temperatures from 0 to 25 °C using the chromogenic substrate <I>o</I>-nitrophenyl-β-galactoside. All substitutions resulted in altered temperature activity profiles compared with wild type, with five of the six clearly exhibiting reduced catalytic efficiency (<I>k</I><SUB>cat</SUB>/<I>K</I><SUB>m</SUB>) at colder temperatures and/or higher efficiency at warmer temperatures. These results could be accounted for by temperature-dependent changes in both <I>K</I><SUB>m</SUB> and <I>k</I><SUB>cat</SUB> (three substitutions) or either <I>K</I><SUB>m</SUB> or <I>k</I><SUB>cat</SUB> (one substitution each). The effects were correlated with perturbation of charge, hydrogen bonding, or packing, likely affecting the temperature-dependent flexibility and function of the enzyme. Our interdisciplinary approach, incorporating comparative genomics, mutagenesis, enzyme kinetics, and modeling, has shown that divergence of a very small number of amino acid residues can account for the cold temperature function of a polyextremophilic enzyme.</P>