Tensile failure(spalling or slabbing)often occurs on the sidewall of deep tunnel,which is closely related to the coupled stress state of deep rock mass under high pre-static load and dynamic disturbance.To reveal the ...Tensile failure(spalling or slabbing)often occurs on the sidewall of deep tunnel,which is closely related to the coupled stress state of deep rock mass under high pre-static load and dynamic disturbance.To reveal the mechanism of rock tensile failure caused by this coupled stress mode,the Brazilian disc tests were carried on red sandstone under high pre-static load induced by dynamic disturbance.Based on the pure static tensile fracture load of red sandstone specimen,two static load levels(80%and 90%of the pure static tensile fracture load)were selected as the initial high pre-static loading state,and then the dynamic disturbance load was applied until the rock specimen was destroyed.The dynamic disturbance loading mode adopted a sinusoidal wave(sine-wave)load,and the loading wave amplitude was 20%and 10%of the pure static tensile fracture load,respectively.The dynamic disturbance frequencies were set to 1,10,20,30,40,and 50 Hz.The results show that the tensile failure strength and peak displacement of red sandstone specimens under coupled load actions are lower than those under pure static tensile load,and both parameters decrease significantly with the increase of dynamic disturbance frequency.With the increase of dynamic disturbance frequency,the decrease range of tensile strength of red sandstone increased from 3.3%to 9.4%when the pre-static load level is 80%.While when the pre-static load level is 90%,the decrease range will increase from 7.4%to 11.6%.This weakening effect of tensile strength shows that the deep surrounding rock is more likely to fail under the coupled load actions of pre-static load and dynamic disturbance.In this tensile failure mechanism of the deep surrounding rock,the stress environment of deep sidewall rock determines that the failure mode of rock is a tensile failure,the pre-static load level dominates the tensile failure strength of surrounding rock,and dynamic disturbance promotes the strength-weakening effect and affects the weakening range.展开更多
The general contact problem of a disc squeezed between jaws of arbitrary curvature is considered employing Muskhelishvili’s complex potentials.Taking advantage of the general solution introduced,the closed-form expre...The general contact problem of a disc squeezed between jaws of arbitrary curvature is considered employing Muskhelishvili’s complex potentials.Taking advantage of the general solution introduced,the closed-form expressions for the stresses along strategic loci(loaded rim,loaded diameter,disc’s center)are obtained,in terms of the ratio r of the disc’s to the jaw’s curvature.Then,the effect of r(as well as that of the relative stiffness of the disc’s and jaw’s materials dictating the contact arc)on the stress distribution along these loci is explored.It is concluded that,for both smooth contact(zero friction)and contact with friction,the role of the jaw’s curvature is significant not only along the disc-jaw contact arc(as it could be expected),but also all along the loaded diameter.On the other hand,it is indicated that the stress field at the disc’s center is more or less insensitive to the jaw’s curvature assuming that r lies within the range(0,0.67)or in other words within the limits defined by the two standardized suggestions,i.e.that of American Society for Testing and Materials(ASTM)(plane loading platens with r ? 0)and that of International Society for Rock Mechanics(ISRM)(curved jaws with r ? 0.67).The upper limit of this range is a kind of compromise between the need to make the stress field at the disc’s center independent of the boundary conditions while keeping at the same time the contact angle large enough to reduce the stress concentration and the risk for premature fracture initiation far from the disc’s center.For jaws with radius of curvature exceeded by that suggested by ISRM,the stress field at the disc’s center is significantly influenced.Especially for jaws with radius approaching that of the disc,the stress field at the disc’s center is dramatically distorted rendering Hondros’ formula inapplicable and the test results erroneous.展开更多
The dry sliding behavior of three commercial friction materials(codenamed FM1,FM2,and FM3)tested against a Co‐free cermet coating produced by high‐velocity oxy‐fuel(HVOF)on gray cast‐iron discs is investigated.FM1...The dry sliding behavior of three commercial friction materials(codenamed FM1,FM2,and FM3)tested against a Co‐free cermet coating produced by high‐velocity oxy‐fuel(HVOF)on gray cast‐iron discs is investigated.FM1 is a conventional low‐metallic friction material,FM2 is developed for using against HVOF‐coated discs,and FM3 is a Cu‐free friction material with a low content of abrasives and a relatively high concentration of steel fibers.For the tribological evaluation,they are tested on a pin‐on‐disc(PoD)test rig against Co‐free HVOF‐coated discs,with particular attention to the running‐in stage,which is fundamental for the establishment of a friction layer between the two mating surfaces,i.e.,the pin and disc.The PoD tests are performed at room temperature(RT)and a high temperature(HT)of 300℃.At RT,all materials exhibit a long running‐in stage.At HT,no running‐in is observed in FM1 and FM2,whereas a shorter running‐in period,with respect to the RT case,is observed in FM3 followed by the attainment of a comparatively high coefficient of friction.At RT,the pin wear is mild in all cases but severe at HT.FM3 shows the lowest wear rate at both temperatures.Moreover,the coated disc shows no wear when sliding against the FM3 friction material.All the results are interpreted considering the microstructural characteristics of the friction layers formed on the sliding surfaces.The findings of the present study provide insights into reducing wear in braking system components and hence reducing environmental particulate matter emissions from their wear,through the use of disc coatings.展开更多
Dynamic tensile failure is a common phenomenon in deep rock practices,and thus accurately evaluating the dynamic tensile responses of rocks under triaxial pressures is of great significance.The Brazilian disc(BD)test ...Dynamic tensile failure is a common phenomenon in deep rock practices,and thus accurately evaluating the dynamic tensile responses of rocks under triaxial pressures is of great significance.The Brazilian disc(BD)test is the suggested method by the International Society for Rock Mechanics and Rock Engineering(ISRM)for measuring both the static and dynamic tensile strengths of rock-like materials.However,due to the overload phenomenon and the complex preloading conditions,the dynamic tensile strengths of rocks measured by the BD tests tend to be overestimated.To address this issue,the dynamic BD tensile strength(BTS)of Fangshan marble(FM)under different preloading conditions were measured through a triaxial split Hopkinson pressure bar(SHPB).The fracture onset in BD specimen was captured through a strain gage around the disc center.The discrepancy between the traditional tensile strength(TTS,determined by the peak load P_(f) of the BD specimen)and the nominal tensile strength(NTS,obtained from the load P_(i) when the diametral fracture commences in the tested BD specimen)was applied to quantitatively evaluating the overload phenomenon.The Griffith criterion was used to rectify the calculation of the tensile stress at the disc center under triaxial stress states.The results demonstrate that the overload ratio(s)increases with the loading rate(σ)and decreases with the hydrostatic pressure(σ_(s)).The TTS corrected by the Griffith criterion is independent of theσ_(s)due to the overload phenomenon,while the NTS corrected by the Griffith criterion is sensitive to both the andσ.Therefore,it is essential to modify the tensile stress in dynamic confined BD tests using both the overload correction and the Griffith criterion rectification to obtain the accurate dynamic BTS of rocks.展开更多
Objective:To screen the antibacterial activity of nine ethnoveterinary plants traditionally used for the treatment of mastitis,wound and gastrointestinal complications.Methods:Hydroalcoholic exctracts of medicinal pla...Objective:To screen the antibacterial activity of nine ethnoveterinary plants traditionally used for the treatment of mastitis,wound and gastrointestinal complications.Methods:Hydroalcoholic exctracts of medicinal plants namely,Achyranthes aspera(A.aspera) L.(Family Asparagaceae),Ficus caria(F.caria)(Family Moraceae).Malvi parviflora(M.parviflora)(Family Malvaceae),Vernonia species(V.species) docal name Alakit.Family Asteraceae),Solatium hastifolium(S.hastifolium)(Family Solanaceae),Calpurinia aurea(C.aurea)(Ait) Benth(Family Fabaceae),Nicotiana tabacum(N.tabacum) L.(Family Solanaceae),Ziziphus spina-christi(Z.spina-christi)(Family Rhamnaceae).Croton macroslachys(C.macrostachys)(Family Fuphorhiaceae).were screened against clinical bacterial isolates of veterinary importance from October 2007 to April2009.The antibacterial activity was tested using disc diffusion at two concentrations(200 mg/mL and 100 mg/mL) and broth dilution methods using 70%methanol macerated leal extracts.Results:With the exception ol S.hastifolium all plant extracts exhibited antibacterial activity.Among the medicinal plants tested C.aurea.C.macrostachyus,A.aspera,N.tabacum and vcrnonia species(Alakit) showed the most promising antimicrobial properties.Conclusions:It can be concluded that many of the tested plants have antibacterial activity and supports the traditional usage of the plants for mastitis,wound and gastrointestinal complications treatment.Further studies into their toxicity and phytochemistry is advocated.展开更多
Background: Detection of Methicillin Resistant Staphylococcus aureus may vary in phenotypic and genotypic methods. Objective: The aim of this present study was to validate the oxacillin screen agar test for the detect...Background: Detection of Methicillin Resistant Staphylococcus aureus may vary in phenotypic and genotypic methods. Objective: The aim of this present study was to validate the oxacillin screen agar test for the detection of methicillin-resistant Staphylococcus aureus isolated from clinical specimens. Methodology: This cross-sectional study was planned to carry out in the Department of Microbiology and Immunology at Bangabandhu Sheikh Mujib Medical University, Dhaka from January, 2010 to December, 2010 for a period of one (01) year. Different clinical specimens were collected from the patients presented with infections at anybody sites. Isolation and identification of Staphylococcus aureus (S. aureus) were performed by staining, culture and biochemical tests. Oxacillin screen agar test was performed to detect the methicillin-resistant Staphylococcus aureus. PCR was performed for detection of the mecA gene for MRSA. Result: Out of the 22 suspected MRSA isolates 19 were mecA positive by PCR. The sensitivity and specificity of oxacillin screen agar were 100.0% (95% CI 82.3 to 100.0%) and 33.3% (95% CI 24.0 to 90.6%) respectively. The positive predictive value and negative predictive value of oxacillin screen agar test were 90.5% (95% CI 81.0 to 95.5%) and 100.0% (95% CI 20.6 to 100.0%) respectively. The accuracy of the oxacillin screen agar test was 90.9% (95% CI 71.7 to 96.3%). Conclusion: In conclusion oxacillin screen agar test has high sensitivity with low specificity for the detection of MRSA.展开更多
Increasing operating speed of modern passenger railway vehicles leads to higher thermal load onthe braking system. Organic composite brake pads are poor thermal conductors, hence frictionalheat is absorbed mainly by t...Increasing operating speed of modern passenger railway vehicles leads to higher thermal load onthe braking system. Organic composite brake pads are poor thermal conductors, hence frictionalheat is absorbed mainly by the disc. In this study three brake pad types were tested on thedynamometer. Metallic fibres, steel and copper, were introduced to the formulation of twomaterials. The third was a non-metallic material - a reference case. Dynamometer test comprisedemergency brake applications to determine the frictional characteristics of the materials andconstant-power drag braking to analyse the effect of metal fibres on temperature evolution,measured by six thermocouples embedded in the brake disc. Mean friction coefficient is analysedand discussed. It is concluded that conductive fibre in the friction material formulation mayinfluence its tribological characteristics. Despite high thermal conductivity, metal fibres in theconcentration tested in this study, did not reduce temperature of the brake disc.展开更多
<b><span style="font-family:Verdana;">Aim: </span></b><span style="font-family:""><span style="font-family:Verdana;">The objective of this study w...<b><span style="font-family:Verdana;">Aim: </span></b><span style="font-family:""><span style="font-family:Verdana;">The objective of this study was to isolate, identify, and explore the </span><i><span style="font-family:Verdana;">in</span></i><span style="font-family:Verdana;">-</span><i><span style="font-family:Verdana;">vitro</span></i><span style="font-family:Verdana;"> antifungal susceptibility pattern of dermatophytes isolated from clinica</span><span style="font-family:Verdana;">lly suspected cases of dermatophytosis (tinea infections) attending th</span><span style="font-family:Verdana;">e Dermatology Department at J.S.S Hospital. </span><b><span style="font-family:Verdana;">Methods: </span></b><span style="font-family:Verdana;">This study was conducted at JSS Medical College and Hospital from December 2016 to December 2017. Clinical samples (e.g., skin scrapings and hair stumps) were collected under asep</span><span style="font-family:Verdana;">tic precautions. The identification of dermatophytes was perfor</span><span style="font-family:Verdana;">med</span><span style="font-family:Verdana;"> through microscopic examination using 10%, 20% & 40% potassium hydroxide (KOH) and culture on Sabouraud dextrose agar (SDA), SDAac, PDA and Dermatophyte test medium (DTM). All dermatophytes isolates were subjected to antifungal susceptibility testing using the agar-base</span><span style="font-family:Verdana;">d disk diffusion (ABDD) and E-test method against Terbinafine, Itraconazole, Fluconazole, and Griseofulvin. Data were analyzed by using Chi square test. </span><b><span style="font-family:Verdana;">Results: </span></b><span style="font-family:Verdana;">A 100 samples were studied, 46% tinea corporis, 2%tinea cruris, 9% tinea pedis, 5% tin</span><span><span style="font-family:Verdana;">ea faciei. The dermatophytes isolated were </span><i><span style="font-family:Verdana;">Trichophyton rubrum</span></i><span style="font-family:Verdana;"> 1</span></span><span style="font-family:Verdana;">1 (35%), </span><i><span style="font-family:Verdana;">Trichophyton mentagrophyte</span></i><span style="font-family:Verdana;"> 8 (25%), </span><i><span style="font-family:Verdana;">Trichophyton tonsurans</span></i><span style="font-family:Verdana;"> 5 (16%), Microsporum gypseum 3</span></span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">(10%), </span><i><span style="font-family:Verdana;">Trichophyton verrucosum</span></i><span style="font-family:Verdana;"> 2 (6%), </span><i><span style="font-family:Verdana;">Trichophyton violaceum</span></i><span style="font-family:Verdana;"> 1</span></span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">(3%) and </span><i><span style="font-family:Verdana;">Microsporum audouinii</span></i><span style="font-family:Verdana;"> 1 (3%). Out of 31 dermatophytes 17 were sensitive to all four antifungal agents within the range of FLC (2</span></span><span style="font-family:""> </span><span style="font-family:Verdana;">-</span><span style="font-family:""> </span><span style="font-family:Verdana;">6</span><span style="font-family:""> </span><span style="font-family:Verdana;">mcg/ml), ITR (0.125</span><span style="font-family:""> </span><span style="font-family:Verdana;">-</span><span style="font-family:""> </span><span style="font-family:Verdana;">2), TER (0.125</span><span style="font-family:""> </span><span style="font-family:Verdana;">-</span><span style="font-family:""> </span><span style="font-family:Verdana;">2), and GRI (0.125</span><span style="font-family:""> </span><span style="font-family:Verdana;">-</span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">2), 5 isolates were resistant in which 2 were resistant to FLC (64.256 mcg/ml), 2 isolates were resistant to TER 2 (32.38 mcg/ml), 1 isolate was resistant to both GRI and TER (16.32 mcg/ml) and 9 isolates were within the intermediate range. </span><b><span style="font-family:Verdana;">Conclusion: </span></b><span style="font-family:Verdana;">Every patient with a tinea infection should be properly studied for a mycological examination and should be treated accordingly. Dermatophyte test medium is more useful as an identification medium in the isolation of dermatophytes. The ABDD method appears to be a simple, cost-effective, and promising method for the evaluation of antifungal susceptibility of dermatophytes. E-test method is the most sensitive method due to the fact that quantitative MICs can be obtained directly from the E-strip. However, the E-test method is expensive and difficult in defining the precise borders of the inhibition zones in dermatophytes</span></span><span style="font-family:Verdana;">.展开更多
基金Projects(42077244,41877272,41472269)supported by the National Natural Science Foundation of ChinaProject(2242020R10023)supported by the Fundamental Research Funds for the Central Universities of Southeast University,China。
文摘Tensile failure(spalling or slabbing)often occurs on the sidewall of deep tunnel,which is closely related to the coupled stress state of deep rock mass under high pre-static load and dynamic disturbance.To reveal the mechanism of rock tensile failure caused by this coupled stress mode,the Brazilian disc tests were carried on red sandstone under high pre-static load induced by dynamic disturbance.Based on the pure static tensile fracture load of red sandstone specimen,two static load levels(80%and 90%of the pure static tensile fracture load)were selected as the initial high pre-static loading state,and then the dynamic disturbance load was applied until the rock specimen was destroyed.The dynamic disturbance loading mode adopted a sinusoidal wave(sine-wave)load,and the loading wave amplitude was 20%and 10%of the pure static tensile fracture load,respectively.The dynamic disturbance frequencies were set to 1,10,20,30,40,and 50 Hz.The results show that the tensile failure strength and peak displacement of red sandstone specimens under coupled load actions are lower than those under pure static tensile load,and both parameters decrease significantly with the increase of dynamic disturbance frequency.With the increase of dynamic disturbance frequency,the decrease range of tensile strength of red sandstone increased from 3.3%to 9.4%when the pre-static load level is 80%.While when the pre-static load level is 90%,the decrease range will increase from 7.4%to 11.6%.This weakening effect of tensile strength shows that the deep surrounding rock is more likely to fail under the coupled load actions of pre-static load and dynamic disturbance.In this tensile failure mechanism of the deep surrounding rock,the stress environment of deep sidewall rock determines that the failure mode of rock is a tensile failure,the pre-static load level dominates the tensile failure strength of surrounding rock,and dynamic disturbance promotes the strength-weakening effect and affects the weakening range.
基金co-financed by the EU(European Social Fund-ESF)Greek National Funds through the Operational Program "Education and Lifelong Learning" of the National Strategic Reference Framework(NSRF)-ResearchFunding Program:THALES:Reinforcement of the interdisciplinary and/or inter-institutional research and innovation
文摘The general contact problem of a disc squeezed between jaws of arbitrary curvature is considered employing Muskhelishvili’s complex potentials.Taking advantage of the general solution introduced,the closed-form expressions for the stresses along strategic loci(loaded rim,loaded diameter,disc’s center)are obtained,in terms of the ratio r of the disc’s to the jaw’s curvature.Then,the effect of r(as well as that of the relative stiffness of the disc’s and jaw’s materials dictating the contact arc)on the stress distribution along these loci is explored.It is concluded that,for both smooth contact(zero friction)and contact with friction,the role of the jaw’s curvature is significant not only along the disc-jaw contact arc(as it could be expected),but also all along the loaded diameter.On the other hand,it is indicated that the stress field at the disc’s center is more or less insensitive to the jaw’s curvature assuming that r lies within the range(0,0.67)or in other words within the limits defined by the two standardized suggestions,i.e.that of American Society for Testing and Materials(ASTM)(plane loading platens with r ? 0)and that of International Society for Rock Mechanics(ISRM)(curved jaws with r ? 0.67).The upper limit of this range is a kind of compromise between the need to make the stress field at the disc’s center independent of the boundary conditions while keeping at the same time the contact angle large enough to reduce the stress concentration and the risk for premature fracture initiation far from the disc’s center.For jaws with radius of curvature exceeded by that suggested by ISRM,the stress field at the disc’s center is significantly influenced.Especially for jaws with radius approaching that of the disc,the stress field at the disc’s center is dramatically distorted rendering Hondros’ formula inapplicable and the test results erroneous.
基金This study was funded by the European Union’s Horizon 2020 Research and Innovation Programme under grant agreement(No.636592(LOWBRASYS project)).
文摘The dry sliding behavior of three commercial friction materials(codenamed FM1,FM2,and FM3)tested against a Co‐free cermet coating produced by high‐velocity oxy‐fuel(HVOF)on gray cast‐iron discs is investigated.FM1 is a conventional low‐metallic friction material,FM2 is developed for using against HVOF‐coated discs,and FM3 is a Cu‐free friction material with a low content of abrasives and a relatively high concentration of steel fibers.For the tribological evaluation,they are tested on a pin‐on‐disc(PoD)test rig against Co‐free HVOF‐coated discs,with particular attention to the running‐in stage,which is fundamental for the establishment of a friction layer between the two mating surfaces,i.e.,the pin and disc.The PoD tests are performed at room temperature(RT)and a high temperature(HT)of 300℃.At RT,all materials exhibit a long running‐in stage.At HT,no running‐in is observed in FM1 and FM2,whereas a shorter running‐in period,with respect to the RT case,is observed in FM3 followed by the attainment of a comparatively high coefficient of friction.At RT,the pin wear is mild in all cases but severe at HT.FM3 shows the lowest wear rate at both temperatures.Moreover,the coated disc shows no wear when sliding against the FM3 friction material.All the results are interpreted considering the microstructural characteristics of the friction layers formed on the sliding surfaces.The findings of the present study provide insights into reducing wear in braking system components and hence reducing environmental particulate matter emissions from their wear,through the use of disc coatings.
基金We acknowledge the funding support from the National Natural Science Foundation of China(Grant Nos.42141010,51879184 and 12172253).
文摘Dynamic tensile failure is a common phenomenon in deep rock practices,and thus accurately evaluating the dynamic tensile responses of rocks under triaxial pressures is of great significance.The Brazilian disc(BD)test is the suggested method by the International Society for Rock Mechanics and Rock Engineering(ISRM)for measuring both the static and dynamic tensile strengths of rock-like materials.However,due to the overload phenomenon and the complex preloading conditions,the dynamic tensile strengths of rocks measured by the BD tests tend to be overestimated.To address this issue,the dynamic BD tensile strength(BTS)of Fangshan marble(FM)under different preloading conditions were measured through a triaxial split Hopkinson pressure bar(SHPB).The fracture onset in BD specimen was captured through a strain gage around the disc center.The discrepancy between the traditional tensile strength(TTS,determined by the peak load P_(f) of the BD specimen)and the nominal tensile strength(NTS,obtained from the load P_(i) when the diametral fracture commences in the tested BD specimen)was applied to quantitatively evaluating the overload phenomenon.The Griffith criterion was used to rectify the calculation of the tensile stress at the disc center under triaxial stress states.The results demonstrate that the overload ratio(s)increases with the loading rate(σ)and decreases with the hydrostatic pressure(σ_(s)).The TTS corrected by the Griffith criterion is independent of theσ_(s)due to the overload phenomenon,while the NTS corrected by the Griffith criterion is sensitive to both the andσ.Therefore,it is essential to modify the tensile stress in dynamic confined BD tests using both the overload correction and the Griffith criterion rectification to obtain the accurate dynamic BTS of rocks.
基金Ethiopian Ministry of Science and Technology research and development grant FVS/11/2008
文摘Objective:To screen the antibacterial activity of nine ethnoveterinary plants traditionally used for the treatment of mastitis,wound and gastrointestinal complications.Methods:Hydroalcoholic exctracts of medicinal plants namely,Achyranthes aspera(A.aspera) L.(Family Asparagaceae),Ficus caria(F.caria)(Family Moraceae).Malvi parviflora(M.parviflora)(Family Malvaceae),Vernonia species(V.species) docal name Alakit.Family Asteraceae),Solatium hastifolium(S.hastifolium)(Family Solanaceae),Calpurinia aurea(C.aurea)(Ait) Benth(Family Fabaceae),Nicotiana tabacum(N.tabacum) L.(Family Solanaceae),Ziziphus spina-christi(Z.spina-christi)(Family Rhamnaceae).Croton macroslachys(C.macrostachys)(Family Fuphorhiaceae).were screened against clinical bacterial isolates of veterinary importance from October 2007 to April2009.The antibacterial activity was tested using disc diffusion at two concentrations(200 mg/mL and 100 mg/mL) and broth dilution methods using 70%methanol macerated leal extracts.Results:With the exception ol S.hastifolium all plant extracts exhibited antibacterial activity.Among the medicinal plants tested C.aurea.C.macrostachyus,A.aspera,N.tabacum and vcrnonia species(Alakit) showed the most promising antimicrobial properties.Conclusions:It can be concluded that many of the tested plants have antibacterial activity and supports the traditional usage of the plants for mastitis,wound and gastrointestinal complications treatment.Further studies into their toxicity and phytochemistry is advocated.
文摘Background: Detection of Methicillin Resistant Staphylococcus aureus may vary in phenotypic and genotypic methods. Objective: The aim of this present study was to validate the oxacillin screen agar test for the detection of methicillin-resistant Staphylococcus aureus isolated from clinical specimens. Methodology: This cross-sectional study was planned to carry out in the Department of Microbiology and Immunology at Bangabandhu Sheikh Mujib Medical University, Dhaka from January, 2010 to December, 2010 for a period of one (01) year. Different clinical specimens were collected from the patients presented with infections at anybody sites. Isolation and identification of Staphylococcus aureus (S. aureus) were performed by staining, culture and biochemical tests. Oxacillin screen agar test was performed to detect the methicillin-resistant Staphylococcus aureus. PCR was performed for detection of the mecA gene for MRSA. Result: Out of the 22 suspected MRSA isolates 19 were mecA positive by PCR. The sensitivity and specificity of oxacillin screen agar were 100.0% (95% CI 82.3 to 100.0%) and 33.3% (95% CI 24.0 to 90.6%) respectively. The positive predictive value and negative predictive value of oxacillin screen agar test were 90.5% (95% CI 81.0 to 95.5%) and 100.0% (95% CI 20.6 to 100.0%) respectively. The accuracy of the oxacillin screen agar test was 90.9% (95% CI 71.7 to 96.3%). Conclusion: In conclusion oxacillin screen agar test has high sensitivity with low specificity for the detection of MRSA.
基金supported by the National Science Centre of Poland (Research project No. 2017/27/B/ST8/01249)
文摘Increasing operating speed of modern passenger railway vehicles leads to higher thermal load onthe braking system. Organic composite brake pads are poor thermal conductors, hence frictionalheat is absorbed mainly by the disc. In this study three brake pad types were tested on thedynamometer. Metallic fibres, steel and copper, were introduced to the formulation of twomaterials. The third was a non-metallic material - a reference case. Dynamometer test comprisedemergency brake applications to determine the frictional characteristics of the materials andconstant-power drag braking to analyse the effect of metal fibres on temperature evolution,measured by six thermocouples embedded in the brake disc. Mean friction coefficient is analysedand discussed. It is concluded that conductive fibre in the friction material formulation mayinfluence its tribological characteristics. Despite high thermal conductivity, metal fibres in theconcentration tested in this study, did not reduce temperature of the brake disc.
文摘<b><span style="font-family:Verdana;">Aim: </span></b><span style="font-family:""><span style="font-family:Verdana;">The objective of this study was to isolate, identify, and explore the </span><i><span style="font-family:Verdana;">in</span></i><span style="font-family:Verdana;">-</span><i><span style="font-family:Verdana;">vitro</span></i><span style="font-family:Verdana;"> antifungal susceptibility pattern of dermatophytes isolated from clinica</span><span style="font-family:Verdana;">lly suspected cases of dermatophytosis (tinea infections) attending th</span><span style="font-family:Verdana;">e Dermatology Department at J.S.S Hospital. </span><b><span style="font-family:Verdana;">Methods: </span></b><span style="font-family:Verdana;">This study was conducted at JSS Medical College and Hospital from December 2016 to December 2017. Clinical samples (e.g., skin scrapings and hair stumps) were collected under asep</span><span style="font-family:Verdana;">tic precautions. The identification of dermatophytes was perfor</span><span style="font-family:Verdana;">med</span><span style="font-family:Verdana;"> through microscopic examination using 10%, 20% & 40% potassium hydroxide (KOH) and culture on Sabouraud dextrose agar (SDA), SDAac, PDA and Dermatophyte test medium (DTM). All dermatophytes isolates were subjected to antifungal susceptibility testing using the agar-base</span><span style="font-family:Verdana;">d disk diffusion (ABDD) and E-test method against Terbinafine, Itraconazole, Fluconazole, and Griseofulvin. Data were analyzed by using Chi square test. </span><b><span style="font-family:Verdana;">Results: </span></b><span style="font-family:Verdana;">A 100 samples were studied, 46% tinea corporis, 2%tinea cruris, 9% tinea pedis, 5% tin</span><span><span style="font-family:Verdana;">ea faciei. The dermatophytes isolated were </span><i><span style="font-family:Verdana;">Trichophyton rubrum</span></i><span style="font-family:Verdana;"> 1</span></span><span style="font-family:Verdana;">1 (35%), </span><i><span style="font-family:Verdana;">Trichophyton mentagrophyte</span></i><span style="font-family:Verdana;"> 8 (25%), </span><i><span style="font-family:Verdana;">Trichophyton tonsurans</span></i><span style="font-family:Verdana;"> 5 (16%), Microsporum gypseum 3</span></span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">(10%), </span><i><span style="font-family:Verdana;">Trichophyton verrucosum</span></i><span style="font-family:Verdana;"> 2 (6%), </span><i><span style="font-family:Verdana;">Trichophyton violaceum</span></i><span style="font-family:Verdana;"> 1</span></span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">(3%) and </span><i><span style="font-family:Verdana;">Microsporum audouinii</span></i><span style="font-family:Verdana;"> 1 (3%). Out of 31 dermatophytes 17 were sensitive to all four antifungal agents within the range of FLC (2</span></span><span style="font-family:""> </span><span style="font-family:Verdana;">-</span><span style="font-family:""> </span><span style="font-family:Verdana;">6</span><span style="font-family:""> </span><span style="font-family:Verdana;">mcg/ml), ITR (0.125</span><span style="font-family:""> </span><span style="font-family:Verdana;">-</span><span style="font-family:""> </span><span style="font-family:Verdana;">2), TER (0.125</span><span style="font-family:""> </span><span style="font-family:Verdana;">-</span><span style="font-family:""> </span><span style="font-family:Verdana;">2), and GRI (0.125</span><span style="font-family:""> </span><span style="font-family:Verdana;">-</span><span style="font-family:""> </span><span style="font-family:""><span style="font-family:Verdana;">2), 5 isolates were resistant in which 2 were resistant to FLC (64.256 mcg/ml), 2 isolates were resistant to TER 2 (32.38 mcg/ml), 1 isolate was resistant to both GRI and TER (16.32 mcg/ml) and 9 isolates were within the intermediate range. </span><b><span style="font-family:Verdana;">Conclusion: </span></b><span style="font-family:Verdana;">Every patient with a tinea infection should be properly studied for a mycological examination and should be treated accordingly. Dermatophyte test medium is more useful as an identification medium in the isolation of dermatophytes. The ABDD method appears to be a simple, cost-effective, and promising method for the evaluation of antifungal susceptibility of dermatophytes. E-test method is the most sensitive method due to the fact that quantitative MICs can be obtained directly from the E-strip. However, the E-test method is expensive and difficult in defining the precise borders of the inhibition zones in dermatophytes</span></span><span style="font-family:Verdana;">.
