Physical Durability Research Articles

High-Performance and Durable Window-Type Air Filter Based on Embedded PVDF-TrFE Nanofibrous Membrane.

Fine inhalable particulate matter (PM2.5) is a harmful airborne pollutant, with serious repercussions to public health worldwide. To prevent the influx of PM2.5 into the indoor living and working space, we conceived the design of a "filtration window" that exhibits efficient PM2.5 filtration capabilities while having sufficient transparency and physical durability. In this work, we demonstrate the successful fabrication of a transparent (∼80%) PM2.5 filter based on nanofibrous poly(vinylidenefluoride-co-trifluoroethylene) (PVDF-TrFE), which captures PM2.5 by electrostatic mechanisms originating from the ferroelectric property of the copolymer. The embedded PVDF-TrFE-based nanofibrous filter exhibits a notable PM2.5 removal efficiency of 93%, which is on par with those of medical-grade face masks. Simultaneously, owing to its dense packing, the PVDF-TrFE nanofibrous filter is highly durable, allowing it to be cleaned with water for reuse, and withstands its structural integrity even under a wind flow of 15 m/s, altogether making it practically viable as a functional window unit.

Influence of rubber aggregates from the recycled tires on the physico-mechanical and durability properties of compressed earth blocks

To meet sustainable development goals, global policies are strongly oriented toward valorizing alternative resources such as local materials and waste from different sectors of activity. This study aims to evaluate the influence of adding rubber aggregates from used/recycled tires (GPU) on the physico-mechanical and durability properties of compressed earth bricks (CEB). The CEB were made with an earthen matrix containing 8% cement, and 0 to 2% mass of GPU. The CEB were cured under ambient conditions (30±5°C) for 28 days. The results showed a real improvement in physical and mechanical performance and durability indicators of CEB with increasing GPU content. The apparent density changed slightly from 1697 kg/m3 to 1733 kg/m3. Total water absorption decreased from 21% to 19% with a slight decrease in water-accessible porosity from 35.7% to 33.1%. The capillary absorption coefficient at 10 minutes also decreased from 14 g/cm2.min1/2 to 10 g/cm2.min1/2 The increase of 29% was noted on the compressive strength in the dry state ranging from 3.5 to 4.5 MPa and of 60% on the compressive strength in the wet state ranging from 1.1 MPa to 1.7 MPa. This resulted in the improvement of the structural efficiency coefficient by 27% ranging from 2080 to 2651 Pa.m3/kg. Abrasion resistance coefficient increased more than 50% ranging from 10.8 to 16.9 cm2/g. By comparing the results to the normative references, the CEB containing GPU can be classified as CEB usable in load-bearing walls in a dry environment and resistant to abrasion.

Cow Dung Biostabilized Earth Mortars: Reusability and Influence of Cow Dung Processing and Cow Diet

Historically, cow dung has been widely used as a biostabilizer in earth building, although the scientific research on this subject is still limited. The available research provides evidence of the positive effects of this bioaddition on earthen blocks and plasters, as it improves their physical and mechanical properties and durability in water contact. The present research does not aim to characterize biostabilized earthen mortars or to explain the interaction mechanisms between the earth and cow dung components, because this topic has already been investigated. Instead, it aims to investigate strategies to optimize the collection and processing of cow dung so as to optimize their effects when used in earth-plastering mortars, as well as considering the effects of using them fresh whole, dry whole, and dry ground (as a powder); the effects of two different volumetric proportions of cow dung addition, 20% and 40% (of the earth + added sand); the effects of 72 h (fermentation–humid curing) before molding the biostabilized mortar; the influence of the cow diet; and the potential of reusing cow dung stabilized mortars. The results show that as the freshness of the cow dung increases, the mortar’s durability increases under water immersion, as well as the mechanical and adhesive strength. Collecting cow dung fresh and drying (composting) it in a plastic container is more efficient than collecting cow dung that is already dry on the pasture. The cow diet and the use of dry (composted) cow dung, whole or ground into a powder, does not result in a significant difference. A 72 h period of humid curing fermentation increases the adhesive strength and durability under water. The proportion of 40% promotes better durability under water, but 20% offers greater mechanical and adhesive strength. Finally, cow dung addition does not reduce the reusability of the earth mortar. The new mortar obtained by remixing the mortar with water presents increased properties in comparison to the original reference mortar with no cow dung addition. Therefore, the contributions of this research are innovative and important, offering technical support in the area of biostabilized earth-plastering mortars. Furthermore, it is emphasized that cow dung addition can be optimized as an efficient traditional solution to increase the mechanical resistance, but especially to increase the durability of earth mortars when in contact with water. This effect is particularly important for communities lacking financial resources, but also reveals the possibility of using eco-efficient waste instead of binders obtained at high firing temperatures.

The attrition, physical and insecticidal durability of two dual active ingredient nets (Interceptor® G2 and Royal Guard®) in Benin, West Africa: results from a durability study embedded in a cluster randomised controlled trial.

Studies evaluating the attrition, physical and insecticidal durability of dual active ingredient (AI) insecticide-treated nets (ITNs) are essential for makingprogrammatic decisions regarding their deployment. We performed a prospective study embedded in a cluster randomised controlled trial (cRCT) to evaluate the attrition, fabric integrity and insecticidal durability of Interceptor® G2 (alpha-cypermethrin-chlorfenapyr) and Royal Guard® (alpha-cypermethrin-pyriproxyfen), compared to Interceptor® (alpha-cypermethrin) in Benin. A total of 2428 study nets in 1093 randomly selected households in five clusters per arm of the cRCT were monitored for ITN attrition and fabric integrity every 6-12months post-distribution. Householders were further surveyed to investigate non-study net use and their preference for ITN fabric types used in the study nets. A second cohort of 120 nets per ITN type were withdrawn every 12months and assessed for chemical content and insecticidal activity in laboratory bioassays. Alpha-cypermethrin bioefficacy was investigated using the susceptible Anopheles gambiae Kisumu strain, and chlorfenapyr and pyriproxyfen bioefficacy were investigated using the pyrethroid-resistant Anopheles coluzzii Akron strain. Net pieces were tested in WHO cone bioassays and tunnel tests for alpha-cypermethrin and in tunnel tests for chlorfenapyr; pyriproxyfen activity was assessed in cone bioassays as the reduction in fertility of blood-fed survivors using ovary dissection. Bioefficacy was expressed as the proportion of ITNs passing predetermined WHO criteria, namely knock-down ≥ 95% or 24/72h mortality ≥ 80% or reduction in fertility ≥ 50%. Overall ITN survivorship was 52% at 24months and fell to 15% at 36months. Median ITN survival time was lower with Royal Guard® relative to Interceptor® [1.6 vs 2.3years; hazard ratio (HR) 1.49, 95% confidence interval (CI) 1.36-1.66; p < 0.001] and Interceptor® G2 (1.6 vs 2.1years; HR 1.33, 95% CI 1.20-1.47; p < 0.001). Householders overwhelmingly preferred polyester nets over polyethylene nets (96%), and more Royal Guard® nets were replaced with spare polyester nets from previous campaigns. All Royal Guard® nets passed efficacy criteria for alpha-cypermethrin at all time points (100%) while ITN pass rates after 24months had fallen to < 40% for pyriproxyfen and chlorfenapyr. The chemical content analysis showed a higher loss rate of the non-pyrethroid insecticides relative to the pyrethroids in each dual ingredient AI ITN; 74% vs 47% for Royal Guard® and 85% vs 63% for Interceptor® G2 at 36months. The median ITN survival time for Interceptor® G2 (2.1years) and Royal Guard® (1.6years) in Benin is substantially lower than 3years. Royal Guard® nets were discarded more quickly by householders, partly due to their low preference for polyethylene nets. The insecticidal activity of the non-pyrethroid insecticides in both dual AI ITNs was short-lived compared to alpha-cypermethrin. The results corroborate the findings from the cRCT conducted in Benin.

Facile preparation of three-dimensional copper foam incorporated with Au/CuO nanorods as a durable, reusable and efficient SERS substrate

An exceptionally durable and recyclable three-dimensional copper foam (CF) modified CuO nanorods with Au nanostructures on its surface is noticeable for the application in surface-enhanced Raman scattering (SERS). The utilization of CF as a 3D frame substrate allowed for the advancement of its beneficial characteristics, such as an increased surface-active area resulting from its high porosity and superior chemical/physical stability. By thermally oxidizing CF at a temperature of 500 °C, CuO nanorods were fabricated directly onto CF to exploit its advantageous properties, such as its high surface-active area and photodegradation effect. Following that, Au nanostructures were deposited onto the surfaces of CuO nanorods via photoreduction. The purpose of incorporating Au nanostructures was to optimize the SERS phenomenon, since Au exhibits high SERS efficiency and excellent surface stability. The Au/CuO@CF SERS substrate demonstrated the capability to measure MB at a concentration of 0.1 nM. Meanwhile, the recyclability of the Au/CuO@CF was evaluated by subjecting it to UV irradiation three times while utilizing MB samples. Subsequently, the Au/CuO@CF substrate's physical durability was evaluated via sandpaper abrasion test. In addition to confirming the long-term usability, the Au/CuO@CF demonstrated its resilience by maintaining good measurement performance even after being subjected to ambient air for up to 25 days.

Enhancing Sustainable Subgrade Engineering Using Soil Tuff for Modifying Iron Tailings Sand: A Comprehensive Engineering Performance and Sustainability Analysis

Soil tuff, an industrial solid waste, can serve as a sustainable alternative to cement for modifying iron tailings sand (ITS). To substantiate this claim, the physical properties, durability and microstructure of soil tuff and cement-modified ITSs were analyzed at different modifier dosages, compaction degrees and maintenance ages, with a comprehensive comparison in the perspective of sustainable built environments. The results indicate that the physical properties of soil tuff-modified ITS (STM-ITS) were significantly enhanced in subgrade engineering applications compared with cement-modified ITS (CM-ITS). In addition, compared with CM-ITS, the hydration products of STM-ITS possessed a smaller amount of Ca(OH)2 and were cemented with surrounding binding products, which resulted in fewer cracks. STM-ITS featured a more stable C–S–H gel than CM-ITS due to a lower Ca/Si ratio, contributing to its higher corrosion resistance. Notably, a sustainability analysis demonstrated that incorporating STM-ITS has physical properties comparable to those of CM-ITS and can be obtained at a significantly lower cost, CO2 emission, and energy consumption. Therefore, this study highlights the potential of soil tuff as a promising eco-friendly option for subgrade engineering, promoting waste usage, improving built environments, and contributing to carbon-neutrality goals. These findings have significant implications for the construction industry and the pursuit of sustainable development.

Anti-Frosting and Defrosting Fins with Hierarchical Interlocking Structure for Enhancing Energy Utilization Efficiency of Heat Exchanger.

Air conditioners, being an indispensable component of contemporary living, consume a significant amount of electricity every year. The accumulation of frost, dust, and water on the fins surface hinders the efficiency of the heat exchange process, thereby reducing the effectiveness of the air conditioning system. To address these limitations, this paper proposes a large-scale and cost-effective method combining compression molding, chemical etching, and spray coating to fabricate aluminum fins (HMNA) with hierarchical interlocking structures. The HMNA exhibits outstanding durability, passive and active anti-icing, anti-frosting and defrosting, and self-cleaning capabilities associated with the robust super-hydrophobicity. The hierarchical interlocking structure effectively enhances the physical and environmental durability of the HMNA. Most significantly, the frost time of the HMNA fins assembled heat exchanger is significantly delayed by ≈700% compared to the traditional Al fins heat exchanger, while the frost layer thickness is reduced by ≈75%. This greatly reduces the frequency with which the defrosting cycle is started, thus effectively improving the efficiency of the air conditioning system. The proposed method for economical and mass production of the HMNA fins can be an excellent candidate for the development of low energy consumption air conditioning system.

Physical performance, durability, and carbon emissions of recycled cement concrete and fully recycled concrete

This study introduces innovative concepts for closed-loop recycling waste concrete to produce fully recycled concrete (FRC). Multiple test methods and characterization techniques were used to evaluate the physical properties and durability of four types of concrete (normal concrete, recycled aggregate concrete, recycled cement concrete and FRC). The fresh density, compressive strength, ultrasonic characteristics, chloride resistance, water adsorption properties, carbonation behaviors, and microstructure characteristics of these concretes were investigated. The water absorption behavior of FRC can be divided into three stages, with the initial stage having a water absorption rate three times that of ordinary concrete. It was found that carbonation depth varied among different concrete types, influenced by binder quality, which can affect the porosity and mechanical properties. Overall, recycled cement concrete and FRC demonstrate considerable potential for reducing carbon emissions, with total emissions of 59.152 kgCO2/m3, representing an 85 % reduction compared to ordinary concrete.

Study on properties of alkali activated titanium gypsum artificial aggregate concrete

Abstract In order to solve the problem of raw material shortage and solid waste disposal in the construction industry, titanium gypsum was used as raw material to prepare titanium gypsum artificial aggregate by alkali-activated cold bonding. The physical properties and microstructure of aggregates were studied, they were used to replace natural aggregates in unfired bricks. The unburned aggregate of ternary cementitious material system (titanium gypsum, cement, silica fume) was designed, and the best artificial aggregate ratio was selected by physical performance analysis, XRD and SEM analysis. The unburned bricks were prepared by replacing natural gravel with different replacement rates. The physical properties and durability were analyzed by physical test, dry and wet cycle test, and the best utilization method was sought. Main research contents and conclusions: (1) When the ratio of titanium gypsum: cement: silica fume = 7: 2: 1, NaOH: CaO = 1: 1 as the activator, the comprehensive performance of artificial aggregate is the best. According to XRD and SEM analysis, the main products in the titanium gypsum artificial aggregate system are C-S-H and AFt. (2) The compressive strength of the unburned brick prepared by titanium gypsum artificial aggregate completely replacing natural gravel reached 31.40 MPa, and the water absorption rate was 10.18 %. The unburned brick specimens with different substitution rates showed good dry-wet cycle resistance after 15 dry-wet cycles.

Physical and Mechanical Properties and Durability Characteristics of New Pultruded GFRP Bars with Thermoplastic Resin

Physical and Mechanical Properties and Durability Characteristics of New Pultruded GFRP Bars with Thermoplastic Resin

Durability of metal oxide nanostructures synthesized by hot water treatment

Metal oxide nanostructures (MONSTRs) have become popular in various fields. This study investigates the durability of MONSTRs synthesized through hot water treatment (HWT) using copper, aluminum, and zinc as the source metals of choice. The physical durability tests include pressure, scratch, and scotch tape adhesion tests, and chemical durability tests such as corrosion resistance tests, heat resistance, and solar exposure tests. Results showed that MONSTRs synthesized from HWT are highly durable under the tested conditions except for NaOH and HCl immersion tests for copper oxide and zinc oxide. The study concluded that HWT is a sustainable synthesis method for MONSTRs.Graphical

Influence of Nano-Silicon Dioxide in the Enhancement of Surface Structure of Public Filler and Properties of Recycled Mortar

This paper proposes a method of enhancing public filler (PF) with nano-SiO2 (NS) to prepare modified recycled aggregate mortar (RAM). The improvement effect of NS solution at different concentrations and immersion times on the macroscopic physical properties of recycled public fine aggregates (PFA) was investigated. Moreover, the effect of NS on the basic physical properties and durability of recycled mortar (RM) and the reinforcement mechanism of NS on recycled mortar was analyzed through various techniques. Results indicated that the modification effect of NS could remove loose cement mortar from the surface of PFA. It reacted with calcium hydroxide and calcite to generate nano-particles that could fill pores in PFA. The water absorption rate of PFA decreased to 9.3% when immersed in 2% NS solution for 72 h. There was no significant improvement in the mechanical properties of RM when the solution concentration and immersion time were increased. However, the compressive strength of RM prepared by modifying PFA with 2% NS was increased by about 21.9%, and the capillary water absorption and electric flux were reduced by 56.3% and 15.1%, respectively. Micro-analysis results showed that the volcanic ash effect of NS enabled it to react with Ca(OH)2 adhered to the surface of PFA, generating C-S-H and improving the interfacial bonding of PFA. Moreover, NS adsorbed on the surface of PFA dispersed into the freshly mixed cement slurry, which further enhanced the internal structure of PFA.

A Comprehensive Experimental Study on the Physical Performance and Durability of Bamboo Bio-Concrete

In recent decades, the building sector has been moving toward promoting renewable raw materials to reduce greenhouse gas emissions associated with construction materials. One of the most valuable alternatives is the use of large-volume fractions of vegetable aggregates, leading to the development of bio-based cement mixture. A review of the recent scientific literature has shown that traditional design rules cannot be applied to bio-based cement mixtures. In this context, this study summarizes the results of a comprehensive experimental campaign aimed at unveiling the influence of bamboo particles on the physical properties and durability indicators of Bamboo Bio-Concrete (BBC) designed by applying a recent methodology proposed by the authors. The mixtures were produced using bamboo particles at a volumetric fraction of 45% and 50%. Fundamental properties such as density, thermal conductivity, capillary water absorption, and drying shrinkage were measured. The results obtained herein highlight the lightweight (density lower than 786 kg/m3) and insulating properties (thermal conductivity within 0.32 to 0.52 W/mK) of the BBC. The capillary absorption ranged between 2.40 and 2.83 g/cm2, whereas the drying shrinkage ranged between 2500 and 5000 µε. These properties indicate the feasibility of using this material in various applications in the construction sector.

Physical and insecticidal durability of Interceptor®, Interceptor® G2, and PermaNet® 3.0 insecticide-treated nets in Burkina Faso: results of durability monitoring in three sites from 2019 to 2022

BackgroundNational Malaria Programmes (NMPs) monitor the durability of insecticide-treated nets (ITNs) to inform procurement and replacement decisions. This is crucial for new dual active ingredients (AI) ITNs, for which less data is available. Pyrethroid-only ITN (Interceptor®) and dual AI (Interceptor® G2, and PermaNet® 3.0) ITNs were assessed across three health districts over 36 months in southern Burkina Faso to estimate median ITN survival, insecticidal efficacy, and to identify factors contributing to field ITN longevity.MethodsDurability was monitored through a prospective study of a cohort of nets distributed during the 2019 mass campaign. Three health districts were selected for their similar pyrethroid-resistance, environmental, epidemiological, and population profiles. Households were recruited after the mass campaign, with annual household questionnaire follow-ups over three years. Each round, ITNs were withdrawn for bioassays and chemical residue testing. Key measures were the percentage of cohort ITNs in serviceable condition, insecticidal effectiveness, and chemical residue content against target dose. Cox proportional hazard models were used to identify determinants influencing ITN survival.ResultsAt endline, the median useful life was 3.2 (95% CI 2.5–4.0) years for PermaNet® 3.0 ITNs in Orodara, 2.6 (95% CI 1.9–3.2) years for Interceptor® G2 ITNs in Banfora and 2.4 (95% CI 1.9–2.9) years for Interceptor® ITNs in Gaoua. Factors associated with ITN survival included cohort ITNs from Orodara (adjusted hazard ratio (aHR) = 0.58, p = 0.026), households seeing less rodents (aHR = 0.66, p = 0.005), female-headed households (aHR = 0.66, p = 0.044), exposure to social behavior change (SBC) messages (aHR = 0.52, ≤ 0.001) and folding nets when not in use (aHR = 0.47, p < 0.001). At endline, PermaNet® 3.0 ITN recorded 24-h mortality of 26% against resistant mosquitos on roof panels, with an 84% reduction in PBO content. Interceptor® G2 ITN 72-h mortality was 51%, with a 67% reduction in chlorfenapyr content. Interceptor® ITN 24-h mortality was 71%, with an 84% reduction in alpha-cypermethrin content.ConclusionOnly PermaNet® 3.0 ITNs surpassed the standard three-year survival threshold. Identified protective factors should inform SBC messaging. Significant decreases in chemical content and resulting impact on bioefficacy warrant more research in other countries to better understand dual AI ITN insecticidal performance.

Evaluation of Sensory Characteristics of Rubber Tree (Hevea Brasiliensis) Sawdust and Leaves as Alternative Biofuels

In the face of rising fuel costs and environmental concerns, the need for alternate energy sources is growing. Charcoal, generated from animal and vegetable sources, has emerged as a viable alternative fuel. Briquetting, which compresses organic materials into compact briquettes, offers an environmentally responsible solution for waste management and energy production in the Philippines. Basilan, noted for its agricultural methods, generates a substantial amount of agricultural waste, including rubberwood sawdust (RBS) and Rubber Tree Leaves which is perfect for briquette production due to its lignocellulose content. Charcoal briquettes, made of charcoal fines and binder, are an economical, smokeless, and long-lasting fuel option which may poses sustainable solution as the conventional method of charcoal manufacture, which involves tree felling, poses ecological concerns. This exploratory experimental design study investigates the viability and possibility of utilizing biocharcoal from dried leaves of rubber trees and rubberwood sawdust (Hevea brasiliensis) as an environmentally benign and cost-effective option. This study intends to create a sustainable cooking fuel alternative to standard charcoal by reusing agricultural trash. The study aims to developed briquettes and assesses their physical characteristics such durability, efficiency, kindling time, burning time, and heating quality to three identified evaluators. Overall, the positive responses from those who were interviewed shed light on the promising potential of rubber sawdust charcoal briquettes (x̄=4.8 (liked very much)) and rubber tree leaves (x̄=4.23 (liked very much)) as a viable and environmentally friendly energy source for applications involving heating and cooking. Due to limited laboratory apparatuses, researchers recommended for a further evaluation of the developed briquettes such doing proximate analysis (e.g. measuring the moisture and ash content) established strong data to support the existing data.

Non-staining resistance to dyes and odors of synthetic leathers composed of polyurethane resins with different glass transition temperatures

The objective of this study was to develop a highly durable synthetic leather with excellent resistance to light discoloration and deterioration without the use of fluorine or silicon and a surface that is resistant to dyes and odors. Environment-friendly biomass feedstock was used as the reaction component. Firstly, polyurethane (PU) resins with varying glass transition temperatures ( Tg) were synthesized. Subsequently, these were used as surface treatment agents for synthetic leather, and the relationship between the non-staining performance of the PU resin and the Tg values was discussed. In addition, the physical durability over time was investigated. The non-staining performance of the synthetic leather surface against dyed clothing and the odor of ammonia evidently depended on the Tg of the PU resin used as the surface treatment agent. The Tg range that is the most convenient for practical purposes, and the related best light discoloration and degradation resistance and bending resistance, were confirmed, and serve as indicators that the material can be used as a highly durable interior material.

Rock Sources for Gravestones at the Islamic Cemetery of Rawansar: A Geological Perspective

Stone has played a crucial role in human history, serving both geological and stratigraphical purposes. Throughout the ages, it has been an essential material, providing raw resources for various applications. From prehistoric lithic tools to architectural elements, stone has significantly impacted our development. In cemeteries, stone has taken on a major role due to its physical resistance and durability. Different communities have considered and traded stones for tombs and graves, recognizing their value in memorialization. In recent years, the importance of stone materials has grown, particularly for grave inscriptions. Today, numerous varieties of stone are used in cemeteries, and the practice of stone trading and selection has expanded for tombstone purposes. An illustration of this transfer and import of stone can be observed in the Islamic cemetery of Ravansar. This cemetery, which is the focus of this article, is primarily composed of geological rocks and indigenous materials, such as limestone from the Bisetoun Formation. However, stones used in the Islamic cemetery of Ravansar, dating back nearly a century, are made of green sandstones specifically sourced from surrounding areas. In a study examining the geological potential for trade routes supplying stone to the Islamic cemetery of Ravansar, researchers have reviewed the available evidence, including social and ethnographic factors. This analysis has been approved and serves as a testament to the historical and cultural significance of stone in our society.

Evaluation of the Physical Durability of Merdeka Basketball Club Athletes

ABSTRAK Penelitian ini dilakukan untuk mengetahui bagaimana daya tahan yang dimiliki oleh di Atlet Basket putra pada club Merdeka di Rejang Lebong. Penelitian yang dilakukan menggunakan metode deskriptif kuantitatif. Alat pengumpulan data pada penelitian ini adalah multistage fitness test. Subjek dari penelitian adalah Atlet Putra yang yang menjadi Anggota Club Merdeka di Rejang Lebong yakni berjumlah sebanyak 15 orang atlet basket putra club merdeka. Analisis data yang digunakan yaitu analisis deskriptif dengan teknik persentase, dan tes yang digunakan yaitu berupa multistafe fitness test atau bleep test. Berdasarkan hasil dari penelitian yang sudah dilakukan didapatkan bahwa daya tahan fisik yang dimiliki oleh Atlet Basket Club Merdeka di Rejang Lebong 7 orang atlet dalam kategori cukup dengan persentase 47%, sedangkan 6 orang dalam kategori baik dengan persentase 40% dan 2 orang atlet dalam kategori sangat baik dengan persentase 13%. Dengan hasil tersebut berdasarkan norma standarisasi, dapat disimpulkan bahwa kemampuan vo2max atlet basket putra club merdeka di Rejang Lebong dinyatakan dalam kategori cukup, baik, dan sangat baik. Kata Kunci : ABSTRACT This research was conducted to find out the endurance of male basketball athletes at the Merdeka club in Rejang Lebong. The research was conducted using quantitative descriptive methods. The data collection tool in this research is the multistage fitness test. The subjects of the research were male athletes who were members of the Merdeka Club in Rejang Lebong, namely 15 men's basketball athletes from the Merdeka Club. The data analysis used is descriptive analysis using percentage techniques, and the test used is a multistafe fitness test or bleep test. Based on the results of research that has been carried out, it was found that the in very good category, the abdominal muscle strength of female athletes was in physical endurance of the Merdeka Basketball Club athletes in Rejang Lebong is 7 athletes in the fair category with a percentage of 47%, while 6 people are in the good categ ory with a percentage of 40% and 2 athletes are in the very category good with a percentage of 13%. With these results based on standardization norms, it can be concluded that the vo2max ability of men's basketball athletes at the Independent Club in Rejang Lebong is stated in the categories of fair, good and very good. Keywords: Baskerball, Endurance, MFT

Physical durability and insecticidal activity of long-lasting insecticidal nets in Cruzeiro do Sul, Brazil

Vector control is one of the principal strategies used for reducing malaria transmission. Long-lasting insecticidal bed nets (LLINs) are a key tool used to protect populations at risk of malaria, since they provide both physical and chemical barriers to prevent human-vector contact. This study aimed to assess the physical durability and insecticidal efficacy of LLINs distributed in Cruzeiro do Sul (CZS), Brazil, after 4 years of use. A total of 3000 LLINs (PermaNet 2.0) were distributed in high malaria risk areas of CZS in 2007. After 4 years of use, 27 ‘rectangular’ LLINs and 28 ‘conical’ LLINs were randomly selected for analysis. The evaluation of physical integrity was based on counting the number of holes and measuring their size and location on the nets. Insecticidal efficacy was evaluated by cone bioassays, and the amount of residual insecticide remaining on the surface of the LLINs was estimated using a colorimetric method. After 4 years of use, physical damage was highly prevalent on the rectangular LLINs, with a total of 473 holes detected across the 27 nets. The upper portion of the side panels sustained the greatest damage in rectangular LLINs. The overall mosquito mortality by cone bioassay was < 80% in 25/27 rectangular LLINs, with panel A (at the end of the rectangular bednet) presenting the highest mortality (54%). The overall mean insecticide concentration was 0.5 µg/sample, with the bednet roof containing the highest average concentration (0.61 µg/sample). On the conical LLINs, 547 holes were detected, with the bottom areas sustaining the greatest damage. The cone bioassay mortality was < 80% in 26/28 of the conical LLINs. The mean insecticide concentration was 0.3 µg/sample. After 4 years of use, the insecticidal efficacy of the LLINs was diminished to below acceptable thresholds.

Effect of chloride binding and sulfate ion attack on the chloride diffusion in calcium sulfoaluminate-based material under seawater environment

The diffusion of chloride ions in reinforced concrete under the seawater environment will affect the physical or mechanical properties and durability. Sulfate ions also influence the diffusion of chloride ions by generating expansion products through physical and chemical reactions. Further research on the effects of chloride binding and sulfate ion attack on chloride ion diffusion will deepen the understanding of concrete failure mechanism. In this paper, a quaternary blend based on calcium sulfoaluminate (CSA) cement was prepared and laboratory immersion tests were conducted in artificial seawater with varying salt concentrations. Initially, chloride ion concentration measurements and XRD tests were conducted at different corrosion ages and salt concentrations. Subsequently, the chloride binding properties of CSA-based materials was quantified through the analysis of chloride ion concentration and the phases of hydration products. Meanwhile, the corrosive effect of sulfate ions on chloride ion diffusion was determined corresponds to the content of expansive hydration products. Furthermore, numerical simulations were employed to evaluate the impact of sulfate ion corrosion, chloride binding, and their combined effects on chloride ion diffusion, and the results were compared with free chloride ion concentration (Cf). The results indicate that the total chloride ion concentration (Ct) exhibits a linear relationship with increasing salt concentrations of seawater in CSA-based materials. Meanwhile, the bound chloride ion concentration (Cb) follows a logarithmic growth pattern. The chloride binding rate experiences a linear decline with the increase of chloride ion concentration in the artificial seawater. Additionally, the relationship between Cf and Cb or Ct can be described using different isothermal adsorption models for the CSA-based materials. Among these models, the Langmuir model is suitable for characterizing the relationship between Cf and Cb, while the Freundlich model is suitable for describing the relationship between Cf and Ct. Furthermore, it is noteworthy that sulfate ion attack and chloride binding exert nearly equivalent effects on the diffusion of chloride ions in CSA-based materials at short corrosion age and low chloride ion concentration. However, the corrosive impact of sulfate ions gradually evolves into the dominant factor in the progression of corrosion over time and the increase in seawater salt concentration.