Results Of Resistance Tests Research Articles

One simple design to improve the mass transfer of low Pt-loaded membrane electrode assembly to realize operation under low humidity

The low Pt-loaded cathode catalyst layer (CCL) design is critical for mass transfer in proton exchange membrane fuel cells (PEMFCs). Meanwhile, the drying of the CCL can lead to high voltage loss of membrane-electrode assemblies (MEAs) at low relative humidity (RH). Here, we use silica (SiO2) as a pore-forming agent to design CCL with a gradient pore structure. The oxygen transport resistance (OTR) test results show that the gas transport capacity of the CCL is significantly improved. According to the polarization curve at low RH, the gradient pore structure in CCL can improve the performance of the MEA. The accelerated stress test (AST) is conducted to explore the durability of these MEAs. The results show that the use of SiO2 to create pores in the CCL does not accelerate the loss of Pt. This optimization method can be practically applied to improve the performance under low RH.

The bactericidal effect of far-UVC on ESBL-producing Escherichia coli

Because extended-spectrum beta-lactamase (ESBL) infections can cause life-threatening disease and effective treatments need to be developed, we examined the bactericidal effect of far-ultraviolet C (far-UVC) light therapy on ESBL-producing Escherichia coli (E. coli). The bactericidal effect on 2 types of ESBL-producing E. coli was the same as that on the wild strain although the results of drug resistance tests varied among these strains. We believe that irradiation with far-UVC is effective in preventing infection by ESBL-producing E. coli in health care settings.

DECAY RESISTANCE OF PRESERVATIVE INJECTED POPLAR AND ITS PROCESS OF PREVENTING WHITE ROT FUNGI INFECTION

This study initiallyinvestigated decay resistance of preservative injected poplar and its infection mechanismof preventing white rot fungi. The living poplar was injected with different concentrations (0.0, 0.5, 1.0 and 1.5 wt.%) of alkaline copper quaternary (ACQ). Using thescanning electron microscopy, the process of preservative injected poplar wood preventing white rot fungi infection at different tree heights were examined. The decay resistance test results showed that the decay resistance of preservative injected poplar at different tree heights was significantly different. With the increase in tree height, the decay resistance decreased, and the higher the ACQ concentration, the better the decay resistance. The white rot fungi infested the poplar wood with the vessels as the breakthrough point, being spread to other cells through pits. The white rot fungi degraded wood cell walls by secreting enzymes and preferentially degraded the parenchyma cells.

Influence of natural zeolite on fresh properties, compressive strength, flexural strength, abrasion resistance, Cantabro-loss and microstructure of self-consolidating concrete

This study aimed to evaluate the effect of natural zeolite (NZ) on some fresh and hardened properties of self-consolidating concrete (SCC). For this purpose, eight mixtures containing 0, 5%, 10%, and 15% NZ as partial replacement of portland cement with two water to binder ratios (w/b) were studied. In order to evaluate the mechanical properties of concrete, compressive strength and four-point bending tests were performed at the ages of 7, 28, and 90 days. The abrasion resistance and Cantabro-loss tests were performed according to ASTM C779-A (procedure A-revolving discs) and ASTM C1747, respectively at the ages of 28 and 90 days. The results indicated that the HRWR demand of SCC mixtures increases with NZ content. However, the viscosity and stability of the mixtures were improved by NZ. Overall, the mechanical properties of SCC mixtures were improved by using NZ. The optimum rate of NZ was found to be 10%. Although the reduction of the w/b ratio had a more significant effect on improving the mechanical properties compared to using NZ, the reduction of the w/b ratio along with the partial replacement of cement with NZ enhanced this effect. In addition, regression analysis showed a strong correlation between the results of abrasion resistance and Cantabro-loss tests. The results of SEM analysis showed a significant reduction in the width, length and number of micro-cracks in the bulk binder paste and the ITZ of 10% NZ mixtures compared to the plain portland cement mixtures. High peak intensities of C-S-H gel and low intensities of ettringite were also observed by XRD analysis in the ITZ of NZ- containing concretes due to pozzolanic reaction.

Post-earthquake fire performance of fire door sets

This paper presents the results of an experimental cyclic and fire test program to investigate the fire performance of fire door sets after experiencing simulated earthquake damage. The earthquake damage mimics that of a 35-story tall residential benchmark building subject to design earthquake intensity level, inducing an inter-story drift of 57 mm. Three earthquake-damaged 90-min rated fire door sets were subject to displacement controlled quasi-static cyclic loading test at ambient temperature and then to standard fire resistance tests. Results of cyclic load tests at ambient temperature reveal severe distortion of the fire door frames and excessive gaps, notably at top corners. Results of the subsequent standard fire resistance tests show that the fire resistance of the damaged fire door sets decreased by as much as 70%. The reduction can be attributed to large gaps due to the distorted door geometry after seismic loading, substantial loosening of the door hinges and damaged intumescent seals around the door. Maximum gap measurement of 8 mm between the door and door frame is considered as the threshold above which the fire compartment is compromised, and fire door set replacement is necessary.

Weight Fraction Effect of Sugar Palm Fiber as Polypropylene-Elastomer Matrix Reinforcement on Fire Resistance of Hybrid Composite

Indonesia is one of the countries with abundant availability of palm fiber (Arenga pinnata), polypropylene (PP), elastomer. By utilizing these three types of materials, it is hoped that they can become new composite materials that have good physical properties and characteristics and are useful in engineering applications. PP and elastomer materials used in this study act as a composite matrix and are reinforced by palm fiber (Arenga pinnata). Composites are generally a new material by combining two or more different materials to produce a new material with better properties than the constituent material itself. This study aims to determine the value of the fire resistance of PP composites and elastomers with sugar palm fiber (Arenga pinnata) reinforcement with various weight fractions of 20 % (80:20), 30 % (70:30), and 40 % (60:40). Based on the fire resistance test results of hybrid polypropylene and elastomeric composites with sugar palm fiber reinforcement (Arenga pinnata) showed that the composite with a fraction of 20 % (80:20) had the lowest linear combustion rate of 0.128 mm/minute. In comparison, the composite with a weight fraction of 40 % (60:40) obtained the highest linear combustion rate of 0.202 mm/minute. For the weight loss rate test, the composite with a weight fraction of 20 % (80:20) got the highest result of 0.759 gram/minute, while the composite with a weight fraction of 40 % (60:40) got the lowest weight loss rate of 0.480 gram/minute.

Non-Pharmacological Treatments for Insulin Resistance: Effective Intervention of Plant-Based Diets-A Critical Review.

Plant-based diets are becoming increasingly popular. Vegetarian diets are better for the environment and exhibit health benefits. A correctly balanced plant-based diet is appropriate at every stage of life. Compared to omnivores, vegetarians consume more fruits and vegetables, more fibre, vitamins C and E, magnesium and less saturated fats. In general, they have better nutrition knowledge, and they are slimmer, healthier and live longer than omnivores. It also seems that following a plant-based diet prevents the onset of chronic diseases such as cardiovascular diseases, hypertension, type 2 diabetes, obesity and some cancers. Food intake has a key influence on insulin resistance. Consumption of calorie-rich and highly processed foods, meats and sweetened beverages is a characteristic element of Western diets. They promote and elevate insulin resistance and type 2 diabetes. In contrast, intake of pulses and exclusion of meats as well as animal products bring significant benefits to vegetarian diets. According to studies, vegetarians and vegans have better blood parameters, including better glucose, insulin, total cholesterol, and LDL cholesterol levels. Their homeostatic model assessment for insulin resistance (HOMA-IR) test results are also better. More plant-based foods and fewer animal foods in a diet result in lower insulin resistance and a lower risk of prediabetes and type 2 diabetes. The aim of the study was to investigate the effect of plant-based diets on insulin resistance. In this review, we focused on presenting the positive effects of vegetarian and vegan diets on insulin resistance while showing possible clinical applications of plant-based diets in the treatment and prevention of modern-age diseases. Current and reliable publications meeting the requirements of Evidence-Based Medicine (EBM) were taken into account in this review.

Virological and Immunological Outcomes of an Intensified Four-Drug versus a Standard Three-Drug Antiretroviral Regimen, Both Integrase Strand Transfer Inhibitor-Based, in Primary HIV Infection.

The optimal therapeutic approach for primary HIV infection (PHI) is still debated. We aimed to compare the viroimmunological response to a four- versus a three-drug regimen, both INSTI-based, in patients with PHI. This was a monocentric, prospective, observational study including all patients diagnosed with PHI from December 2014 to April 2018. Antiretroviral therapy (ART) was started, before genotype resistance test results, with tenofovir/emtricitabine and either raltegravir plus boosted darunavir or dolutegravir. Cumulative probability of virological suppression [VS] (HIV-1 RNA< 40 cp/mL), low-level HIV-1 DNA [LL-HIVDNA] (HIV-1 DNA < 200 copies/106PBMC), and CD4/CD8 ratio ≥1 were estimated using Kaplan–Meier curves. Factors associated with the achievement of VS, LL-HIVDNA, and CD4/CD8 ≥ 1 were assessed by a Cox regression model. We enrolled 144 patients (95.8% male, median age 34 years): 110 (76%) started a four-drug-based therapy, and 34 (24%) a three-drug regimen. Both treatment groups showed a comparable high probability of achieving VS and a similar probability of reaching LL-HIVDNA and a CD4/CD8 ratio ≥1 after 48 weeks from ART initiation. Higher baseline HIV-1 RNA and HIV-1 DNA levels lowered the chance of VS, whereas a better preserved immunocompetence increased that chance. Not statistically significant factors associated with LL-HIVDNA achievement were found, whereas a higher baseline CD4/CD8 ratio predicted the achievement of immune recovery. In PHI patients, the rapid initiation of either an intensified four-drug or a standard three-drug INSTI-based regimen showed comparable responses in terms of VS, viral reservoir size, and immunological recovery.

Investigation on improving corrosion resistance of rare earth pyrosilicates by high-entropy design with RE-doping

To combine the advantages of the thermal expansion coefficient and excellent corrosion resistance to calcium-magnesium-alumino-silicate (CMAS), two types of high-entropy pyrosilicates ((Yb0.2Y0.2Lu0.2Ho0.2Er0.2)2Si2O7 and (Yb0.25Lu0.25Ho0.25Er0.25)2Si2O7) and two single-component pyrosilicates (Yb2Si2O7 and Lu2Si2O7) were prepared by the solid-phase method. CMAS corrosion resistance test results showed that the high-entropy pyrosilicates that form a stable β phase could precipitate apatite (Ca2RE8(SiO4)6O2) more easily than Yb2Si2O7 and Lu2Si2O7 during the corrosion process to protect the block from CMAS. The results provide a theoretical basis for the selection of rare earth elements in high-entropy pyrosilicate according to the radius of different rare earth cation.

Comparable Results of Helicobacter pylori Antibiotic Resistance Testing of Stools vs Gastric Biopsies Using Next-Generation Sequencing

Comparable Results of Helicobacter pylori Antibiotic Resistance Testing of Stools vs Gastric Biopsies Using Next-Generation Sequencing

Influence of Preheating Temperature on Structural and Mechanical Properties of a Laser-Welded MMC Cobalt Based Coating Reinforced by TiC and PCD Particles.

This article presents research on the structural and mechanical properties of an innovative metal matrix composite (MMC) coating designed for use in conditions of intense metal-mineral abrasive wear. The layer, which is intended to protect the working surface of drilling tools used in the oil and natural gas extraction sector, was padded using the multi-run technique on a sheet made of AISI 4715 low-alloy structural steel by Laser Direct Metal Deposition (LDMD) using a high-power fiber laser (FL). An innovative cobalt alloy matrix powder with a ceramic reinforcement of crushed titanium carbide (TiC) and tungsten-coated synthetic polycrystalline diamond (PCD) was used as the surfacing material. The influence of the preheating temperature of the base material on the susceptibility to cracking and abrasive wear of the composite coating was assessed. The structural properties of the coating were characterized by using methods such as optical microscopy, scanning electron microscopy (SEM), energy dispersion spectroscopy (EDS), transmission electron microscopy (TEM) and X-ray diffraction analysis (XRD). The mechanical properties of the hardfaced coating were assessed on the basis of the results of a metal-mineral abrasive wear resistance test, hardness measurement, and the observation of the abrasion area with a scanning laser microscope. The results of laboratory tests showed a slight dissolution of the tungsten coating protecting the synthetic PCD particles and the transfer of its components into the metallic matrix of the composite. Moreover, it was proved that an increase in the preheating temperature of the base material prior to welding has a positive effect on reducing the susceptibility of the coating to cracking, reducing the porosity of the metal deposit and increasing the resistance to abrasive wear.

Microstructure and wear behavior of AlCrTiNbMo high-entropy alloy coating prepared by electron beam cladding on Ti600 substrate

High-entropy alloys have been widely studied as a new and excellent material in the field of surface protection. To improve the low surface hardness and wear resistance of Ti600 alloy, AlCrTiNbMo high-entropy alloy (HEA) coating was prepared by electron beam cladding. The phase structure and microstructure showed the presence of two BCC solid solution phases A2 and B2 within HEA coating. Laves phase Ti3Al and intermetallic compound Mo3Al8 were also present in the coating. The results of hardness and wear resistance tests showed that the microhardness of coating is 813.5 HV0.2，while substrate is 370.7 HV0.2. The mass loss of coating is only 1.02 mg after wear test, while the mass loss of Ti600 is 38.81 mg. There are cracks and delaminations on the worn surface of Ti600, and wear mechanism is a mixture of micro-ploughing and micro-cutting. The worn surface of HEA coating contains only shear surface traces, and the wear mechanism is micro-cutting. The width and depth of grooves on the worn surface of HEA coating are nearly 10 times that of Ti600 substrate. AlCrTiNbMo HEA coating can be used as an excellent wear-resistant coating with wide application prospect.

In-situ intercalation of montmorillonite/urushiol titanium polymer nanocomposite for anti-corrosion and anti-aging of epoxy coatings

Metal corrosion leads to serious losses. Herein, we developed a new anti-corrosion coating from natural raw materials, montmorillonite (MMT) and urushiol. In-situ polymerization was used to synthesize urushiol titanium polymer intercalated montmorillonite (UTPOMMT), and the UTPOMMT was then added to epoxy resin (EP) to obtain composite coatings (UTPOMMT/EP). This approach of incorporating urushiol titanium polymer in the MMT increased the spacing between MMT layers, and as a result, the layers were more peelable in the epoxy resin and more compactly packed, thereby increasing the barrier properties of the coating. The results of corrosion resistance test showed that the amount of UTPOMMT added to the EP had a significant effect on the anti-corrosion performance of the composite coatings. Among the prepared composites with different loadings, the composite coating containing 5 wt% of UTPOMMT had the best corrosion resistance and salt spray resistance. Compared to the pure epoxy resin, the 5 wt% UTPOMMT composite had the lowest Icorr value (3.29 × 10−10 A·cm−2), the highest the protection efficiency (97.5%), and the longest salt spray resistance time (1032 h). In addition, the results of UV accelerated aging tests showed that the UTPOMMT/PE composite coatings had excellent aging resistance, and the composite coating prepared with 5 wt% UTPOMMT also had the longest aging resistance time of 720 h. Due to the synergistic effects of the montmorillonite and urushiol titanium polymer, the prepared UTPOMMT/EP composites had effective anti-corrosion and anti-aging properties and could be used as a framework for significantly extending the service life of anti-corrosion coatings.

Development of ATO as an alternative catalyst support for PEM fuel cells

Proton exchange membrane (PEM) fuel cells demonstrated to be feasible energy converters that convert chemical energy of fuels to electrical energy. The technology has proven to be competitive with conventional energy converters such as batteries and internal combustion engines. However; several challenges influence the commercialization of this technology which includes high costs, durability, and stability, which are contributed by the PEM fuel cell catalysts. Currently, the carbon-supported platinum electro-catalyst is being used. Unfortunately, carbon supports are not stable enough for fuel cell durability due to carbon corrosion on the cathode. Therefore it is necessary to replace carbon support materials to improve the durability of PEM fuel cells. In this study, antimony doped tin oxide (ATO) metal oxides are synthesized as alternative platinum catalyst support via co-precipitation with different antimony doping levels of 5, 7, and 10 %. The preliminary results of the acid resistance test show that the support is relatively acid-resistant with minor loss of dopant in acidic conditions. Surface area measurements, XRD, TEM, ICP characterization will be performed on the ATO before and after the addition of 40 wt. % of Pt particles. The mass and specific activity measurements for oxygen reduction reaction (ORR) and durability via ex-situ thin-fil rotating disc electrode (RDE) of Pt/ATO catalyst and the traditionally used Pt/C catalyst will be compared.

Performance Engineered Concrete Mixtures: Implementation at an Interstate Rigid Pavement Project

Performance engineered concrete mixtures (PEM) include optimized mixture designs which, paired with advanced quality assurance methods, provide substantially improved durability, economy, and sustainability. One agency challenge to implementation of PEM has been engagement of contractors and other industry stakeholders in field deployment. In this case, an agency, North Carolina Department of Transportation (NCDOT), US, found a willing contractor partner to support an initial concrete paving PEM implementation project. The collaborative effort supported both agency PEM implementation initiatives and provided benefits to the contractor. PEM tests included the Box Test, Super Air Meter (SAM), and surface resistivity, as “shadow tests.” The contractor found the Box Test useful for mixture development and evaluation of modifications during the project. The SAM and resistivity meter were readily implemented into standard quality control (QC) testing without additional QC staff. SAM tests were performed over the course of the project, but the data was variable, and additional training is needed to support improved results. Surface resistivity test results indicated the contractor improved concrete consistency over the two project phases, and the concrete should provide good durability performance. The contractor intends to implement PEM tests for QC on future projects to help improve pavement quality. The agency found surface resistivity tests for acceptance easy to perform. For mixtures containing fly ash, research is needed to identify a 28-day surface resistivity target that generally correlates to a 56-day or 90-day resistivity that predicts good durability performance. This experience reinforced that collaboration between agency, industry, and academia will support advancement of PEM initiatives.

Prevalence of HIV-1 transmitted drug resistance and its impact on the effectiveness of antiretroviral therapy - Minas Gerais state, Brazil / Prevalência de resistência transmitida do HIV-1 e seu impacto na efetividade da terapia antirretroviral – Minas Gerais, Brasil

The transmission and occurrence of resistance associated mutations (RAMs) are among the challenges for a successful HIV Treatment. Therefore, continuous HIV drug resistance surveillance of prevalence and incidence is recommended. The objective this study was to analyze the prevalence and impact of transmitted drug resistance (TDR) on the first-line ART effectiveness. This is a retrospective observational study that evaluated HIV-1-infected treatment-naïve individuals with pre-antiretroviral therapy (ART) genotype resistance test results, between 2014 and 2015, in Minas Gerais state’s, Brazil. The ART effectiveness was compared in individual with and without TDR, considering viral load (VL) 50 copies/mL at the 12 and 24-month endpoint. Reverse transcriptase and protease sequences were genotyped by Sanger sequencing. A total of 170 individuals were selected. HIV-1 subtype B was highly prevalent (63.5%) and prevalence of TDR was 14.1%. That included 62.5% RAMs associated with non-nucleoside reverse-transcriptase inhibitors (NNRTIs), 29.2% with nucleos(t)ide transcriptase inhibitors (NRTIs) and 25% with protease inhibitors (PIs). The overall ART effectiveness measured at 12 and 24 months was, respectively: 91.0% and 93.4% between individuals without TDR; 88.2% and 93.3% in individuals with TDR. Among the individuals starting first-line ART with less than three active drugs (16/24), seven individuals achieved VL 50 copies/mL in the presence of K103N mutation and receiving efavirenz-containing ART. Moderate prevalence of TDR was observed in this study, although observed that some NNRTI TDR, did not impact on the effectiveness of efavirenz-based regimens, without major differences on the effectiveness of first-line ART between the groups with or without TDR.

Evaluation of Gayo coffee germplasm on Hypothenemus hampei (Coleoptera: Curculionidae) resistances

The Gayo Experimental Station (GES) germplasm has the most complete collection of Arabica coffee in the world. The utilization of these collections to search coffee berry borer (CBB) resistant lines has not been carried out. This study aimed to evaluate 17 germplasm lines/varieties of Arabica coffee in GES against CBB resistance. Observation of CBB infestation level in the field was conducted at GES, Bener Meriah, Aceh. Each line used 10 trees and randomly selected 4 branches. Then the number of CBB-infested and healthy cherries were counted. At harvest time, were taken from each line 100 cherries randomly. Parameters observed were cherry weight, discus diameters, and cherries infested. Genetical resistance tests carried out at the plant protection laboratory of IIBCRI, Sukabumi, West Java. The parameter observed was the number of cherries infested. The results showed that CBB infestation level in germplasm was very low, caused by environmental factors that are not suitable for CBB development. There was a positive correlation between cherry discus diameters and CBB infestation rate. The results of genetic resistance testing in the laboratory showed that all of the evaluated Gayo arabica coffee lines/varieties showed a lightly susceptible response to CBB.

Fire Resistance of Aluminum-Glass Partitions with a Parallel Structure of Intumescent Layers

Aim: The aim of the article is to verify the fire resistance of aluminum-glass construction partitions with a parallel structure. The paper presents the results of tests in a fire chamber of a selected partition, a leading national manufacturer of aluminum-glass systems. The results of the fire tests were used to validate a simple parallel model of the reliability of non-renewable systems. Introduction: Fire-retardant properties of partitions made of glass and aluminum profiles determine their ability to stop the spread of fire by clos - ing the fire in separate zones. Fire resistance of such partitions is measured according to various criteria, in particular the requirements concern: stability R (glass does not break), tightness E, radiation limitation W and insulation I. The tightness requirement E means that the partition effectively protects the fire compartment against flames, smoke and hot gases. The insulating postulate I means that the average temperature of glass and the profiles on the surface of the partition on the protected side does not exceed the contractual value during the nominal duration of the fire. The measure of fire resistance of a partition is time t, expressed in minutes, in which the structure of an aluminum-glass partition meets one or more of the criteria listed. Methodology: The experimental database consists of the results of routine fire resistance tests of system building partitions obtained in the certification process of selected facade systems. Interpretation of the obtained results of laboratory tests was based on simple models of reliability of non-renewable systems. Conclusions: The graphs of average temperature increase on the outer surface of the tested glass are the same in each case in terms of quality and quantity. Up to about 70% of the nominal fire resistance, the temperature increase is linear, followed by a non-linear phase according to a concave curve. The course of the temperature-rise curves on the outer surface of aluminum profiles is qualitatively different. The graphs are non-linear, convex from the beginning of heating, with the inflection point reached after about 20 minutes of the test. The obtained results may indicate that the multi-chamber structure of aluminum profiles does not ensure a parallel reliability structure, because the object has a quasi-parallel structure. The presented results of the temperature-rise curves and their reliability interpretation require confirmation in further laboratory tests of aluminum-glass partitions with a different structure of panes and profiles. Keywords: glass, partitions, laboratory tests, fire resistance, reliability Type of article: case study

Experimental and Simulation Research of Belt Extrusion Process Based on Simplified Chip Model

The projectile extrusion process is an extremely important part of the initial trajectory of the artillery launch. The differentiation of the extrusion process brings about the stability problem of the extrusion process, which directly affects the stability and safety of the artillery, ballistic and projectile launching process. sex. Since the simplified chip intrusion resistance model does not pay attention to the projectile movement process and the formation process of the elastic belt groove, and only studies the change law of the intrusion resistance, the model is relatively simple and the parameters are easy to determine. In this paper, a quasi-static test device for the extrusion process of the elastic belt is established. The model is calibrated with the simplified chip resistance model with the intrusion process. Finally, the model is used to calculate the resistance along the process of a large-caliber howitzer projectile extrusion process, and it is compared with the embedded resistance test results of a large-caliber howitzer., the results show that in the whole process of extrusion, the relative error between the calculated value of the total extrusion resistance and the experimental value is basically below 10%, and the maximum relative error is 10.98%, which verifies the accuracy of the model.

Design of an impact absorbing green composite

The goal of this study is to build impact-absorbing bio-composite panels from bio-resin and denim wastes that can help solid waste management. Within this scope, composite structures with different layer numbers are produced using waste denim fabric and epoxy:AESO (70:30) matrix material. The panels produced in different number of layers are subjected to physical (density and fiber weight ratio) and mechanical (drop-weight resistance) tests. The drop impact resistance test results show the increasing number of layers in the composite structure improves the impact resistance.