Polymer-based materials have been motivated to be an alternative support system element in the mining/tunneling industry due to their logistic and geotechnical benefits.Thin spray-on liner(TSL),a term to define the ap...Polymer-based materials have been motivated to be an alternative support system element in the mining/tunneling industry due to their logistic and geotechnical benefits.Thin spray-on liner(TSL),a term to define the application of the material on the rock surface with a layer ranging from 2 mm to10 mm in thickness,shows some promising results.TSLs are mainly composed of plastic,polymer,or cement-based ingredients to a certain proportion.This study intends to reveal the time-dependent response of TSL specimens,cured throughout 500 d,under four constant stress levels for stable laboratory conditions.The results were correlated using two interrelated equations to predict the material’s service life(creep-rupture envelopes).The proposed correlations offered an insight into both the effective permanent support time and the strain amount at the liner failure.The time-dependent deformation of TSL,whose performance is highly responsive to creep behavior,was obtained so that the design engineers may use the findings to avoid the severe problems of material creep.Experimental data were also used to develop a Burgers(four-element)creep model.Since the liner has a nonlinear time-dependent behavior,creep models were built for each stress level separately.Subsequently,a generic equation was obtained using the nonlinear parametric dependencies.There is a good agreement between the proposed model and the experimental results.The proposed model can be used as a basis for future numerical studies related to the support behavior of aged surface support liners.展开更多
The manuscript titled "Vacuoles of Candida yeast behave as a specialized niche for Helicobacter pylori(H.pylori)" not only has not been prepared in a scientific manner but the methodology used was not adequa...The manuscript titled "Vacuoles of Candida yeast behave as a specialized niche for Helicobacter pylori(H.pylori)" not only has not been prepared in a scientific manner but the methodology used was not adequate, and therefore the conclusion reached was not correct. First of all, "yeast" is a broad terminology covering a great number of genera and species of unicellular micro-organisms. The authors should have defined the organism with its binary scientific name. This measure would allow experiment reproduction by the scientific community. Moreover, the criteria established by Robert Koch to identify a specific microorganism or pathogen was not adopted in the methodology used. Regarding the methodology applied, use of the chicken eggyolk(Ig Y) antibody and PCR of the apparently tainted yeast population to prove H. pylori existence in the yeast vacuoles might be main factors for their wrong conclusions. Bacterial tropism toward yeast extract is a known phenomenon, and yeast extract is one of the main ingredients in culture media. Their internalization through phagocytosis or similar pathways does not seem possible or practical because of the thick and cellulosic yeast wall. While the small size of yeast cells does not support their ability in harboring several H. pylori, other observations such as inefficiency of antifungal therapy as anti-Helicobacter therapy strongly reject the conclusion reached by the above-mentioned article.展开更多
Background:Hypertension is one of the leading causes of death in developed and developing countries that need urgent strategies to implement interventions.Appropriate lifestyle modification practices are the corner st...Background:Hypertension is one of the leading causes of death in developed and developing countries that need urgent strategies to implement interventions.Appropriate lifestyle modification practices are the corner stone of the prevention and control.Objective:To assess lifestyle modification practices and associated factors among hypertensive patients.Methods:A facility-based cross-sectional study was conducted among hypertensive patients from 1 April to 30 April 2019.Simple random sampling was used to select the study subjects.Data were entered to EpiData 3.1 and exported to Statistical Package for Social Sciences,version 25.0,for analysis.A binary logistic regression analysis was performed to determine predictors of lifestyle modifications among hypertensive patients.Results:The findings of this study revealed that the level of lifestyle modification practice was 79(39.5%).This finding is very low,and it has a significant effect on the management of hypertensive disorders and hypertension-related acute and chronic complications.Ethnicity,family history of hypertension,and knowledge about hypertension were identified as predictors of lifestyle modification practice.Conclusions:In this study,lifestyle modification practice is low(about 40%),but scientifically,almost all hypertensive patients on follow-up should practice lifestyle modification modalities.展开更多
Surface sediment samples collected from the north-eastern Mediterranean were analysed for their geochemical and sedimentological properties. The sediment texture of the studied area represents a wide variety of sedime...Surface sediment samples collected from the north-eastern Mediterranean were analysed for their geochemical and sedimentological properties. The sediment texture of the studied area represents a wide variety of sediment types (extending from sandy gravel to mud) and is characterized by relatively high mud content with varying silt and clay fractions. Due to the rich presence of biogenic materials, several coarse-grained sediment patches displaying high CaCO3 content occur. The organic carbon content of the sediments mainly reflects the standard Mediterranean production of organic matter. There are some exceptional areas in coastal zones which result from pollution by perennial river discharge.展开更多
Cell-substrate interactions play a crucial role in the design of better biomaterials and integration ofimplants with the tissues. Adhesion is the binding process of the cells to the substrate through interactionsbetwe...Cell-substrate interactions play a crucial role in the design of better biomaterials and integration ofimplants with the tissues. Adhesion is the binding process of the cells to the substrate through interactionsbetween the surface molecules of the cell membrane and the substrate. There are severalfactors that affect cell adhesion including substrate surface chemistry, topography, and stiffness. Thesefactors physically and chemically guide and influence the adhesion strength, spreading, shape and fate ofthe cell. Recently, technological advances enabled us to precisely engineer the geometry and chemistry ofsubstrate surfaces enabling the control of the interaction cells with the substrate. Some of the mostcommonly used surface engineering methods for eliciting the desired cellular responses on biomaterialsare photolithography, electron beam lithography, microcontact printing, and microfluidics. Thesemethods allow production of nano- and micron level substrate features that can control cell adhesion,migration, differentiation, shape of the cells and the nuclei as well as measurement of the forces involvedin such activities. This review aims to summarize the current techniques and associate these techniqueswith cellular responses in order to emphasize the effect of chemistry, dimensions, density and design ofsurface patterns on cell-substrate interactions. We conclude with future projections in the field of cellsubstrateinteractions in the hope of providing an outlook for the future studies.展开更多
The ultrastructure of the bone provides a unique mechanical strength against compressive, torsional andtensional stresses. An elastin-like recombinamer (ELR) with a nucleation sequence for hydroxyapatitewas incorporat...The ultrastructure of the bone provides a unique mechanical strength against compressive, torsional andtensional stresses. An elastin-like recombinamer (ELR) with a nucleation sequence for hydroxyapatitewas incorporated into films prepared from a collagen-silk fibroin blend carrying microchannel patternsto stimulate anisotropic osteogenesis. SEM and fluorescence microscopy showed the alignment ofadipose-derived stem cells (ADSCs) and the human osteoblasts (HOBs) on the ridges and in the groovesof microchannel patterned collagen-fibroin-ELR blend films. The Young's modulus and the ultimatetensile strength (UTS) of untreated films were 0.58 ± 0.13 MPa and 0.18 ± 0.05 MPa, respectively. After 28days of cell culture, ADSC seeded film had a Young's modulus of 1.21 ± 0.42 MPa and UTS of0.32 ± 0.15 MPa which were about 3 fold higher than HOB seeded films. The difference in Young'smodulus was statistically significant (p: 0.02). ADSCs attached, proliferated and mineralized better thanthe HOBs. In the light of these results, ADSCs served as a better cell source than HOBs for bone tissueengineering of collagen-fibroin-ELR based constructs used in this study. We have thus shown theenhancement in the tensile mechanical properties of the bone tissue engineered scaffolds by usingADSCs.展开更多
The Cu-In-Zn-Se thin film was synthesized by changing the contribution of In in chalcopyrite CulnSe2 with Zn. The XRD spectra of the films showed the characteristic diffraction peaks in a good agreement with the quate...The Cu-In-Zn-Se thin film was synthesized by changing the contribution of In in chalcopyrite CulnSe2 with Zn. The XRD spectra of the films showed the characteristic diffraction peaks in a good agreement with the quaternary Cu-In-Zn-Se compound. They were in the polycrystalline nature without any post-thermal process, and the main orientation was found to be in the (112) direction with tetragonal crystalline structure. With increasing annealing temperature, the peak intensities in preferred orientation became more pronounced and grain sizes were in increasing behavior from 6.0 to 25.0 nm. The samples had almost the same atomic composition of Cu0.sIn0.sZnSe2. However, EDS results of the deposited films indicated that there was Se re-evaporation and/or segregation with the annealing in the structure of the film. According to the optical analysis, the transmittance values of the films increased with the annealing temperature. The absorption coefficient of the films was calculated as around 105 cm-1 in the visible region. Moreover, optical band gap values were found to be changing in between 2.12 and 2.28 eV depending on annealing temperature. The temperature-dependent dark- and photo-conductivity measurements were carried out to investigate the electrical characteristics of the films.展开更多
基金the Scientific and Technological Research Council of Turkey,TUBITAK(Grant No.115M581)for financial support。
文摘Polymer-based materials have been motivated to be an alternative support system element in the mining/tunneling industry due to their logistic and geotechnical benefits.Thin spray-on liner(TSL),a term to define the application of the material on the rock surface with a layer ranging from 2 mm to10 mm in thickness,shows some promising results.TSLs are mainly composed of plastic,polymer,or cement-based ingredients to a certain proportion.This study intends to reveal the time-dependent response of TSL specimens,cured throughout 500 d,under four constant stress levels for stable laboratory conditions.The results were correlated using two interrelated equations to predict the material’s service life(creep-rupture envelopes).The proposed correlations offered an insight into both the effective permanent support time and the strain amount at the liner failure.The time-dependent deformation of TSL,whose performance is highly responsive to creep behavior,was obtained so that the design engineers may use the findings to avoid the severe problems of material creep.Experimental data were also used to develop a Burgers(four-element)creep model.Since the liner has a nonlinear time-dependent behavior,creep models were built for each stress level separately.Subsequently,a generic equation was obtained using the nonlinear parametric dependencies.There is a good agreement between the proposed model and the experimental results.The proposed model can be used as a basis for future numerical studies related to the support behavior of aged surface support liners.
文摘The manuscript titled "Vacuoles of Candida yeast behave as a specialized niche for Helicobacter pylori(H.pylori)" not only has not been prepared in a scientific manner but the methodology used was not adequate, and therefore the conclusion reached was not correct. First of all, "yeast" is a broad terminology covering a great number of genera and species of unicellular micro-organisms. The authors should have defined the organism with its binary scientific name. This measure would allow experiment reproduction by the scientific community. Moreover, the criteria established by Robert Koch to identify a specific microorganism or pathogen was not adopted in the methodology used. Regarding the methodology applied, use of the chicken eggyolk(Ig Y) antibody and PCR of the apparently tainted yeast population to prove H. pylori existence in the yeast vacuoles might be main factors for their wrong conclusions. Bacterial tropism toward yeast extract is a known phenomenon, and yeast extract is one of the main ingredients in culture media. Their internalization through phagocytosis or similar pathways does not seem possible or practical because of the thick and cellulosic yeast wall. While the small size of yeast cells does not support their ability in harboring several H. pylori, other observations such as inefficiency of antifungal therapy as anti-Helicobacter therapy strongly reject the conclusion reached by the above-mentioned article.
文摘Background:Hypertension is one of the leading causes of death in developed and developing countries that need urgent strategies to implement interventions.Appropriate lifestyle modification practices are the corner stone of the prevention and control.Objective:To assess lifestyle modification practices and associated factors among hypertensive patients.Methods:A facility-based cross-sectional study was conducted among hypertensive patients from 1 April to 30 April 2019.Simple random sampling was used to select the study subjects.Data were entered to EpiData 3.1 and exported to Statistical Package for Social Sciences,version 25.0,for analysis.A binary logistic regression analysis was performed to determine predictors of lifestyle modifications among hypertensive patients.Results:The findings of this study revealed that the level of lifestyle modification practice was 79(39.5%).This finding is very low,and it has a significant effect on the management of hypertensive disorders and hypertension-related acute and chronic complications.Ethnicity,family history of hypertension,and knowledge about hypertension were identified as predictors of lifestyle modification practice.Conclusions:In this study,lifestyle modification practice is low(about 40%),but scientifically,almost all hypertensive patients on follow-up should practice lifestyle modification modalities.
基金partly supported by UNEP and the Turkish Scientific and Technical Research Council(TUBITAK).
文摘Surface sediment samples collected from the north-eastern Mediterranean were analysed for their geochemical and sedimentological properties. The sediment texture of the studied area represents a wide variety of sediment types (extending from sandy gravel to mud) and is characterized by relatively high mud content with varying silt and clay fractions. Due to the rich presence of biogenic materials, several coarse-grained sediment patches displaying high CaCO3 content occur. The organic carbon content of the sediments mainly reflects the standard Mediterranean production of organic matter. There are some exceptional areas in coastal zones which result from pollution by perennial river discharge.
文摘Cell-substrate interactions play a crucial role in the design of better biomaterials and integration ofimplants with the tissues. Adhesion is the binding process of the cells to the substrate through interactionsbetween the surface molecules of the cell membrane and the substrate. There are severalfactors that affect cell adhesion including substrate surface chemistry, topography, and stiffness. Thesefactors physically and chemically guide and influence the adhesion strength, spreading, shape and fate ofthe cell. Recently, technological advances enabled us to precisely engineer the geometry and chemistry ofsubstrate surfaces enabling the control of the interaction cells with the substrate. Some of the mostcommonly used surface engineering methods for eliciting the desired cellular responses on biomaterialsare photolithography, electron beam lithography, microcontact printing, and microfluidics. Thesemethods allow production of nano- and micron level substrate features that can control cell adhesion,migration, differentiation, shape of the cells and the nuclei as well as measurement of the forces involvedin such activities. This review aims to summarize the current techniques and associate these techniqueswith cellular responses in order to emphasize the effect of chemistry, dimensions, density and design ofsurface patterns on cell-substrate interactions. We conclude with future projections in the field of cellsubstrateinteractions in the hope of providing an outlook for the future studies.
基金The authors would like to thank METU(BAP-07.02.2013.101)for the financial support of the study by E.S.the Scientific and Technological Research Council of Turkey(TUBITAK)for the scholarship to E.S.through BIDEB 2211C+1 种基金We are grateful to Ministry of Development of Turkey for funding BIOMATEN through Grant DPT2011K120350J.C.R.C.acknowledges the funding from the EC(HEALTH-F4-2011-278557,PITN-GA-2012-317306,MSCA-ITN-2014-642687 and NMP-2014-646075),MINECO(MAT2013-42473-R and MAT2015-68901R)and JCyL(VA244U13,VA313U14 and VA015U16).
文摘The ultrastructure of the bone provides a unique mechanical strength against compressive, torsional andtensional stresses. An elastin-like recombinamer (ELR) with a nucleation sequence for hydroxyapatitewas incorporated into films prepared from a collagen-silk fibroin blend carrying microchannel patternsto stimulate anisotropic osteogenesis. SEM and fluorescence microscopy showed the alignment ofadipose-derived stem cells (ADSCs) and the human osteoblasts (HOBs) on the ridges and in the groovesof microchannel patterned collagen-fibroin-ELR blend films. The Young's modulus and the ultimatetensile strength (UTS) of untreated films were 0.58 ± 0.13 MPa and 0.18 ± 0.05 MPa, respectively. After 28days of cell culture, ADSC seeded film had a Young's modulus of 1.21 ± 0.42 MPa and UTS of0.32 ± 0.15 MPa which were about 3 fold higher than HOB seeded films. The difference in Young'smodulus was statistically significant (p: 0.02). ADSCs attached, proliferated and mineralized better thanthe HOBs. In the light of these results, ADSCs served as a better cell source than HOBs for bone tissueengineering of collagen-fibroin-ELR based constructs used in this study. We have thus shown theenhancement in the tensile mechanical properties of the bone tissue engineered scaffolds by usingADSCs.
文摘The Cu-In-Zn-Se thin film was synthesized by changing the contribution of In in chalcopyrite CulnSe2 with Zn. The XRD spectra of the films showed the characteristic diffraction peaks in a good agreement with the quaternary Cu-In-Zn-Se compound. They were in the polycrystalline nature without any post-thermal process, and the main orientation was found to be in the (112) direction with tetragonal crystalline structure. With increasing annealing temperature, the peak intensities in preferred orientation became more pronounced and grain sizes were in increasing behavior from 6.0 to 25.0 nm. The samples had almost the same atomic composition of Cu0.sIn0.sZnSe2. However, EDS results of the deposited films indicated that there was Se re-evaporation and/or segregation with the annealing in the structure of the film. According to the optical analysis, the transmittance values of the films increased with the annealing temperature. The absorption coefficient of the films was calculated as around 105 cm-1 in the visible region. Moreover, optical band gap values were found to be changing in between 2.12 and 2.28 eV depending on annealing temperature. The temperature-dependent dark- and photo-conductivity measurements were carried out to investigate the electrical characteristics of the films.