Search results for: strength resistance

Authors: Petros Gkotsis, Giorgos Stratidis, Manassis Mitrakas, Anastasios Zouboulis

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This study investigates the use of original and pre-polymerized iron (Fe) reagents compared to the commonly applied polyaluminum chloride (PACl) coagulant for surface water treatment. Applicable coagulants included both ferric chloride (FeCl₃) and ferric sulfate (Fe₂(SO₄)₃) and their pre-polymerized Fe reagents, such as polyferric sulfate (PFS) and polyferric chloride (PFCl). The efficiency of coagulants was evaluated by the removal of natural organic matter (NOM) and suspended solids (SS), which were determined in terms of reducing the UV absorption at 254 nm and turbidity, respectively. The residual metal concentration (Fe and Al) was also measured. Coagulants were added at five concentrations (1, 2, 3, 4 and 5 mg/L) and three pH values (7.0, 7.3 and 7.6). Experiments were conducted in a jar-test device, with two types of synthetic surface water (i.e., of high and low organic strength) which consisted of humic acid (HA) and kaolin at different concentrations (5 mg/L and 50 mg/L). After the coagulation/flocculation process, clean water was separated with filters of pore size 0.45 μm. Filtration was also conducted before the addition of coagulants in order to compare the ‘net’ effect of the coagulation/flocculation process on the examined parameters (UV at 254 nm, turbidity, and residual metal concentration). Results showed that the use of PACl resulted in the highest removal of humics for both types of surface water. For the surface water of high organic strength (humic acid-kaolin, 50 mg/L-50 mg/L), the highest removal of humics was observed at the highest coagulant dosage of 5 mg/L and at pH=7. On the contrary, turbidity was not significantly affected by the coagulant dosage. However, the use of PACl decreased turbidity the most, especially when the surface water of high organic strength was employed. As expected, the application of coagulation/flocculation prior to filtration improved NOM removal but slightly affected turbidity. Finally, the residual Fe concentration (0.01-0.1 mg/L) was much lower than the residual Al concentration (0.1-0.25 mg/L).

Keywords: coagulation/flocculation, iron and aluminum coagulants, metal salts, pre-polymerized coagulants, surface water treatment

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Authors: Vatsal Patel, Niraj Shah

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This paper presents the results of a laboratory study on the properties of binary blended High Performance cementitious systems containing blends of ordinary Portland cement (OPC), Porcelain Powder or Marble Powder blend proportions of 100:00, 95:05, 90:10, 85:15, 80:20 for OPC: Porcelain Powder/Marble Powder. Studies on the Engineering Properties of the cementitious concrete, namely compressive strength, flexural strength, sorptivity, rapid chloride penetration test and accelerated corrosion test have been performed and those of OPC concrete. The results show that the inclusion of Porcelain powder or Marble Powder as binary blended cement alters to a great degree the properties of the binder as well as the resulting concrete. In addition, the results show that the Porcelain powder with 85:15 proportions and Marble powder with 90:10 proportions as binary systems to produce high-performance concrete could potentially be used in the concrete construction industry particular in lowering down the volume of OPC used and lowering emission of CO2 produces during manufacturing of cement.

Keywords: accelerated corrosion, binary blended cementitious system, rapid chloride penetration, sorptivity

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Authors: S. Al-Enezi, J. Samuel, A. Al-Banna

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Polymer based membranes are one of the low-cost technologies available for the gas separation. Three major elements required for a commercial gas separating membrane are high permeability, high selectivity, and good mechanical strength. Poly(vinylidene fluoride) (PVDF) is a commercially available fluoropolymer and a widely used membrane material in gas separation devices since it possesses remarkable thermal, chemical stability, and excellent mechanical strength. The PVDF membrane was chemically modified by soaking in different ionic liquids and dried. The thermal behavior of modified membranes was investigated by differential scanning calorimetry (DSC), and thermogravimetry (TGA), and the results clearly show the best affinity between the ionic liquid and the polymer support. The porous structure of the PVDF membranes was clearly seen in the scanning electron microscopy (SEM) images. The CO₂ permeability of blended membranes was explored in comparison with the unmodified matrix. The ionic liquid immobilized in the hydrophobic PVDF support exhibited good performance for separations of CO₂/N₂. The improved permeability of modified membrane (PVDF-IL) is attributed to the high concentration of nitrogen rich imidazolium moieties.

Keywords: PVDF, polymer membrane, gas permeability, CO₂ separation, nanotubes

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Authors: O. A. Apampa, Y. A. Jimoh

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The paper reports the investigation of Corn Cob Ash as a chemical stabilizing agent for laterite soils. Corn cob feedstock was obtained from Maya, a rural community in the derived savannah agro-ecological zone of South-Western Nigeria and burnt to ashes of pozzolanic quality. Reddish brown silty clayey sand material characterized as AASHTO A-2-6(3) lateritic material was obtained from a borrow pit in Abeokuta and subjected to strength characterization tests according to BS 1377: 2000. The soil was subsequently mixed with CCA in varying percentages of 0-7.5% at 1.5% intervals. The influence of CCA stabilized soil was determined for the Atterberg limits, compaction characteristics, CBR and the unconfined compression strength. The tests were repeated on laterite cement-soil mixture in order to establish a basis for comparison. The result shows a similarity in the compaction characteristics of soil-cement and soil-CCA. With increasing addition of binder from 1.5% to 7.5%, Maximum Dry Density progressively declined while the OMC steadily increased. For the CBR, the maximum positive impact was observed at 1.5% CCA addition at a value of 85% compared to the control value of 65% for the cement stabilization, but declined steadily thereafter with increasing addition of CCA, while that of soil-cement continued to increase with increasing addition of cement beyond 1.5% though at a relatively slow rate. Similar behavior was observed in the UCS values for the soil-CCA mix, increasing from a control value of 0.4 MN/m2 to 1.0 MN/m2 at 1.5% CCA and declining thereafter, while that for soil-cement continued to increase with increasing cement addition, but at a slower rate. This paper demonstrates that CCA is effective for chemical stabilization of a typical Nigerian AASHTO A-2-6 lateritic soil at maximum stabilizer content limit of 1.5% and therefore recommends its use as a way of finding further application for agricultural waste products and achievement of environmental sustainability in line with the ideals of the millennium development goals because of the economic and technical feasibility of the processing of the cobs from corn.

Keywords: corn cob ash, pozzolan, cement, laterite, stabilizing agent, cation exchange capacity

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Authors: Ilham Zaidi, P. Sankara Sarma, Quazi Taufique Ahmed, V. Raman Kutty, Khalid Umer Khayyam, Gurpreet Singh, Abhishek Royal

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Introduction: Tuberculosis is a global public health emergency, but it is particularly acute in India, which has the world's highest tuberculosis burden. Due to overpopulation, lack of sanitation, malnutrition, low living standards, and poor socioeconomic status, among other factors, it is India's most common infectious disease. The long period of treatment is one of the main reasons for considering it as a public health emergency. Consequently, there is an increase in patient noncompliance, which leads to treatment failure, adverse treatment outcomes, and deaths. This could lead to the growth of anti-TB drug resistance. According to the WHO, approximately 558 thousand new cases of Multi-Drug Resistance Tuberculosis were diagnosed worldwide, with 8.5 percent developed Extensively Drug Resistance Tuberculosis. Methodology: This study is a program-based cross-sectional descriptive survey of adult tuberculosis patients enrolled in the Delhi-based Revised National Tuberculosis Program. The study setting was 27 NTEP districts of Delhi. (N=65,893) and Sample size- was 200; the sampling method which is used in the study was the systemic random sampling method. Results: Most of the demographic factors (age, gender, residence, and family type) were not significantly associated with adherence; marital status was found statistically significant with the treatment compliance. Hesitation while telling people about the disease and motivation to strictly follow drug schedule by healthcare workers were other factors where a significant association with drug adherence was observed. The study findings also suggest that provision of food, minimal financial and other moral support from family, counseling, discussion and politeness by healthcare providers might also facilitate adherence. Discussion and Conclusions: For TB treatment, adherence, age, sex, socioeconomic status, types of accommodations, malnutrition, and personal hygiene should all be considered; similar results were observed in previous studies. In the care of TB patients, DOTS services, health workers, and family support play a significant role. According to the country's National Strategic Plan, the Indian government has set a goal of eliminating tuberculosis by 2025 and patients' compliance with TB care and treatment adherence is very crucial to achieve this aim. A cohort study will be able to give a better understanding of factors associated with adherence since this study may have missed some defaulters who were absconding and could not be reached. Important Terms: RNTCP, NTEP, DOTS, DS-TB, DR-TB, RR-TB, MDR-TB, XDR-TB, Treatment failure, Treatment relapse, Treatment adherence.

Keywords: treatment adherence, treatment relapse, treatment failure, drug resistance tuberculosis

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Authors: Roxana Maria Angelescu, Doina Răducanu, Mariana Lucia Angelescu, Ion Cincă, Vasile Dănuţ Cojocaru, Cosmin Cotruț, Şerban Nicolae

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Titanium alloys are often used for biomedical applications as hard tissue replacements, such as: orthopedic implants, spinal fixation devices and dental implants. Their advantages are well known and demonstrated: excellent mechanical properties, biocompatibility and good corrosion resistance, but it is also known that the main disadvantage of the metallic materials is their tendency of corrosion in in-vivo environments. In 1987, titanium was found to be the only metallic biomaterial that osseointegrates. The aim of this study was to investigate the microstructure and the corrosion behavior of the Ti-20Nb-5Ta wt% alloy. In this case Nb stabilizes the β-Ti structure and Ta is a highly passivating metal. The as studied alloy was melt under argon protective atmosphere in a levitation induction melting furnace, type FIVE CELES - MP25, with a nominal power of 25 kW and a melting capacity of 30 cm3. The microstructure of the as studied alloy was analyzed by using the electronic microscope Tescan Vega II-XMU. The phase structure of the as studied alloy was determined, as well as the crystalline grain size (100-200µ). To determine the corrosion behavior of the as studied alloy, the technique used was the linear polarization, with the PARSTAT 4000 potentiostat, produced by Princeton Applied Research; potentiodynamic curves were obtained with the VeraStudio v.2.4.2 software.

Keywords: corrosion resistance, microstructure, titanium alloys

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Authors: U. Achutha Kini, S. S. Sharma, K. Jagannath, P. R. Prabhu, M. C. Gowri Shankar

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Aluminium matrix composites with alumina reinforcements give superior mechanical & physical properties. Their applications in several fields like automobile, aerospace, defense, sports, electronics, bio-medical and other industrial purposes are becoming essential for the last several decades. In the present work, fabrication of hybrid composite was done by Stir casting technique using Al 6061 as a matrix with alumina and silicon carbide (SiC) as reinforcement materials. The weight percentage of alumina is varied from 2 to 4% and the silicon carbide weight percentage is maintained constant at 2%. Hardness and wear tests are performed in the as cast and heat treated conditions. Age hardening treatment was performed on the specimen with solutionizing at 550°C, aging at two temperatures (150 and 200°C) for different time durations. Hardness distribution curves are drawn and peak hardness values are recorded. Hardness increase was very sensitive with respect to the decrease in aging temperature. There was an improvement in wear resistance of the peak aged material when aged at lower temperature. Also increase in weight percent of alumina, increases wear resistance at lower temperature but opposite behavior was seen when aged at higher temperature.

Keywords: hybrid composite, hardness test, wear test, heat treatment, pin on disc wear testing machine

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Authors: Irena Vuković-Kwiatkowska, Halina Kaczmarek

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Poly (lactic acid) is well known polymer, often called green material because of its origin (renewable resources) and biodegradability. This biopolymer can be used in the packaging industry very often. Poor resistance to permeation of gases is the disadvantage of poly (lactic acid). The permeability of gases and vapor through the films applied for packages and bottles generally should be very low to prolong products shelf-life. We propose innovation method of PLA gas barrier modification using electromagnetic radiation in ultraviolet range. Poly (lactic acid) (PLA) and multifunctional acrylate monomers were mixed in different composition. Final films were obtained by photochemical reaction (photocrosslinking). We tested permeability to water vapor and carbon dioxide through these films. Also their resistance to UV radiation was also studied. The samples were conditioned in the activated sludge and in the natural soil to test their biodegradability. An innovative method of PLA modification allows to expand its usage, and can reduce the future costs of waste management what is the result of consuming such materials like PET and HDPE. Implementation of our material for packaging will contribute to the protection of the environment from the harmful effects of extremely difficult to biodegrade materials made from PET or other plastic

Keywords: interpenetrating polymer network, packaging films, photocrosslinking, polyacrylates dipentaerythritol pentaacrylate DPEPA, poly (lactic acid), polymer biodegradation

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Authors: P. Abachi, S. Karami, K. Purazrang

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The amorphous reinforcements (metallic glasses) can be considered as promising options for reinforcing light-weight aluminum and its alloys. By using the proper type of reinforcement, one can overcome to drawbacks such as interfacial de-cohesion and undesirable reactions which can be created at ceramic particle and metallic matrix interface. In this work, the Zr-based amorphous phase was produced via mechanical milling of elemental powders. Based on Miedema semi-empirical Model and diagrams for formation enthalpies and/or Gibbs free energies of Zr-Cu amorphous phase in comparison with the crystalline phase, the glass formability range was predicted. The composite was produced using the powder mixture of the aluminum and metallic glass and spark plasma sintering (SPS) at the temperature slightly above the glass transition Tg of the metallic glass particles. The selected temperature and rapid sintering route were suitable for consolidation of an aluminum matrix without crystallization of amorphous phase. To characterize amorphous phase formation, X-ray diffraction (XRD) phase analyses were performed on powder mixture after specified intervals of milling. The microstructure of the composite was studied by optical and scanning electron microscope (SEM). Uniaxial compression tests were carried out on composite specimens with the dimension of 4 mm long and a cross-section of 2 ˟ 2mm2. The micrographs indicated an appropriate reinforcement distribution in the metallic matrix. The comparison of stress–strain curves of the consolidated composite and the non-reinforced Al matrix alloy in compression showed that the enhancement of yield strength and mechanical strength are combined with an appreciable plastic strain at fracture. It can be concluded that metallic glasses (amorphous phases) are alternative reinforcement material for lightweight metal matrix composites capable of producing high strength and adequate ductility. However, this is in the expense of minor density increase.

Keywords: aluminum matrix composite, amorphous phase, mechanical alloying, spark plasma sintering

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Authors: Serap Durkut, A. Eser Elcin, Y. Murat Elcin

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Stimuli-sensitive polymeric hydrogels have received extensive attention in the biomedical field due to their sensitivity to physical and chemical stimuli (temperature, pH, ionic strength, light, etc.). This study describes the rheological properties of a novel thermoresponsive poly(N-vinylcaprolactam)-g-collagen hydrogel. In the study, we first synthesized a facile and novel synthetic carboxyl group-terminated thermo-responsive poly(N-vinylcaprolactam)-COOH (PNVCL-COOH) via free radical polymerization. Further, this compound was effectively grafted with native collagen, by utilizing the covalent bond between the carboxylic acid groups at the end of the chains and amine groups of the collagen using cross-linking agent (EDC/NHS), forming PNVCL-g-Col. Newly-formed hybrid hydrogel displayed novel properties, such as increased mechanical strength and thermoresponsive characteristics. PNVCL-g-Col showed low critical solution temperature (LCST) at 38ºC, which is very close to the body temperature. Rheological studies determine structural–mechanical properties of the materials and serve as a valuable tool for characterizing. The rheological properties of hydrogels are described in terms of two dynamic mechanical properties: the elastic modulus G′ (also known as dynamic rigidity) representing the reversible stored energy of the system, and the viscous modulus G″, representing the irreversible energy loss. In order to characterize the PNVCL-g-Col, the rheological properties were measured in terms of the function of temperature and time during phase transition. Below the LCST, favorable interactions allowed the dissolution of the polymer in water via hydrogen bonding. At temperatures above the LCST, PNVCL molecules within PNVCL-g-Col aggregated due to dehydration, causing the hydrogel structure to become dense. When the temperature reached ~36ºC, both the G′ and G″ values crossed over. This indicates that PNVCL-g-Col underwent a sol-gel transition, forming an elastic network. Following temperature plateau at 38ºC, near human body temperature the sample displayed stable elastic network characteristics. The G′ and G″ values of the PNVCL-g-Col solutions sharply increased at 6-9 minute interval, due to rapid transformation into gel-like state and formation of elastic networks. Copolymerization with collagen leads to an increase in G′, as collagen structure contains a flexible polymer chain, which bestows its elastic properties. Elasticity of the proposed structure correlates with the number of intermolecular cross-links in the hydrogel network, increasing viscosity. However, at 8 minutes, G′ and G″ values sharply decreased for pure collagen solutions due to the decomposition of the elastic and viscose network. Complex viscosity is related to the mechanical performance and resistance opposing deformation of the hydrogel. Complex viscosity of PNVCL-g-Col hydrogel was drastically changed with temperature and the mechanical performance of PNVCL-g-Col hydrogel network increased, exhibiting lesser deformation. Rheological assessment of the novel thermo-responsive PNVCL-g-Col hydrogel, exhibited that the network has stronger mechanical properties due to both permanent stable covalent bonds and physical interactions, such as hydrogen- and hydrophobic bonds depending on temperature.

Keywords: poly(N-vinylcaprolactam)-g-collagen, thermoresponsive polymer, rheology, elastic modulus, stimuli-sensitive

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Authors: K. N. Ashna

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Lightweight fills are a viable alternative where weak soils such as soft clay, peat, and loose silt are encountered. Materials such as Expanded Polystyrene (EPS) geo-foam, plastics, tire wastes, rubber wastes have been used along with soil in order to obtain a lightweight fill. Out of these, Expanded Polystyrene (EPS) geo-foam has gained wide popularity in civil engineering over the past years due to its wide variety of applications. It is extremely lightweight, durable and is available in various densities to meet the strength requirements. It can be used as backfill behind retaining walls to reduce lateral load, as a fill over soft clay or weak soils to prevent the excessive settlements and to reduce seismic forces. Geo-foam is available in block form as well as beads form. In this project Expanded Polystyrene (EPS) beads of various diameters and varying densities were mixed along with sand to study their lightweight as well as strength properties. Four types of EPS beads were used 1mm, 2mm, 3-7 mm and a mix of 1-7 mm. In this project, EPS beads were varied at .25%, .5%, .75% and 1% by weight of sand. A water content of 10% by weight of sand was added to prevent segregation of the mixture. Unconsolidated Unconfined (UU) tri-axial test was conducted at 100kPa, 200 kPa and 300 kPa and angle of internal friction, and cohesion was obtained. Unit weight of the mix was obtained for a relative density of 65%. The results showed that by increasing the EPS content by weight, maximum deviator stress, unit weight, angle of internal friction and initial elastic modulus decreased. An optimum EPS bead content was arrived at by considering the strength as well as the unit weight. The stress-strain behaviour of the mix was found to be dependent on type of bead, bead content and density of the beads. Finally, regression equations were developed to predict the initial elastic modulus of the mix.

Keywords: expanded polystyrene beads, geofoam, lightweight fills, stress-strain behavior, triaxial test

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Authors: P. Raajeswari, S. M. Devatha, R. Pragatheeswari

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The edible packaging is a new trendsetter in the era of modern packaging. The researchers and food scientist recognise edible packaging as a useful alternative or addition to conventional packaging to reduce waste and to create novel applications for improving product stability. Starch was extracted from different sources that contains abundantly like potato, tapioca, rice, wheat, and corn. The starch based edible films and cutleries are developed as an alternative for conventional packages providing the nutritional benefit when consumed along with the food. The development of starch based edible films by the extraction of starch from various raw ingredients at lab scale level. The films are developed by the employment of plasticiser at different concentrations of 1.5ml and 2ml. The films developed using glycerol as a plasticiser in filmogenic solution to increase the flexibility and plasticity of film. It reduces intra and intermolecular forces in starch, and it increases the mobility of starch based edible films. The films developed are tested for its functional properties such as thickness, tensile strength, elongation at break, moisture permeability, moisture content, and puncture strength. The cutleries like spoons and cups are prepared by making dough and rolling the starch along with water. The overall results showed that starch based edible films absorbed less moisture, and they also contributed to the low moisture permeability with high tensile strength. Food colorants extracted from red onion peel, pumpkin, and red amaranth adds on the nutritive value, colour, and attraction when incorporated in edible cutleries, and it doesn’t influence the functional properties. Addition of a low quantity of glycerol in edible films and colour extraction from onion peel, pumpkin, and red amaranth enhances biodegradability and provides a good quantity of nutrients when consumed. Therefore, due to its multiple advantages, food starch can serve as the best response for eco-friendly industrial products aimed to replace single use plastics at low cost.

Keywords: edible films, edible cutleries, plasticizer, glycerol, starch, functional property

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Authors: R. Ziaie Moayed, M. Hossein Zade

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Out of all methods for ground improvement, stone column became more popular these days due to its simple construction and economic consideration. Installation of stone column especially in loose fine graded soil causes increasing in load bearing capacity and settlement reduction. Encased granular stone columns (EGCs) are commonly subjected to vertical load. However, they may also be subjected to significant amount of shear loading. In this study, three-dimensional finite element (FE) analyses were conducted to estimate the shear load capacity of EGCs in sandy soil. Two types of different cases, stone column and geosynthetic encased stone column were studied at different normal pressures varying from 15 kPa to 75 kPa. Also, the effect of diameter in two cases was considered. A close agreement between the experimental and numerical curves of shear stress - horizontal displacement trend line is observed. The obtained result showed that, by increasing the normal pressure and diameter of stone column, higher shear strength is mobilized by soil; however, in the case of encased stone column, increasing the diameter had more dominated effect in mobilized shear strength.

Keywords: encased stone column, laterally load, ordinary stone column, validation

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Authors: T. Boonkang, C. Santhaweesuk, N. Pianthong, P. Neeramon, A. Phimhlo, S. Bangphan

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The objective of this research was to apply metakaolin from northeast of Thailand as a binder in the casting process of rice polishing cylinder in replacement of the imported calcined magnesite cement and to reduce the production cost of the cylinder. Metakaolin was obtained from three different regions (Udon Thani, Nakhon Phanom, and Ubon Ratchathani). The design of experiment analysis using the MINITAB Release 14 based on the compressive strength and tensile strength testing was conducted. According to the analysis results, it was found that the optimal proportions were calcined magnesite cement: metakaolin from Udon Thani, Nakhon Phanom and Ubon Ratchathani equal to 63:37, 71:29, and 100:0, respectively. When used this formula to cast the cylinder and test the rice milling, it was found that the average broken rice percent was 32.52 and 38.29 for the cylinder contained the metakaolin from Udon Thani and Nakhon Phanom, respectively, which implied that the cylinder which contained the metakaolin from Udon Thani has higher efficiency than the cylinder which contained the metakaolin from Nakhon Phanom at 0.05 level of statistical significance. Whereas, the average wear rate of cylinder from both resources were 7.27 and 6.53 g/h, respectively.

Keywords: binder, casting, metakaolin, rice polishing cylinder

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Authors: Samera Salimpour Abkenar

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In traditional dyeing of natural fibers with natural dyes, metal salts are commonly used to increase color stability. This method always carries the risk of environmental pollution (contamination of arable soils and fresh groundwater) due to the release of dyeing effluents containing large amounts of metal. Therefore, researchers are always looking for new methods to obtain a green dyeing system. In this research, the use of the enzymatic dyeing method to prevent environmental pollution with metals and reduce production costs has been proposed. After degumming and bleaching, raw silk fabrics were dyed with natural dyes (Madder and Sumac) by three methods (pre-mordanting with a metal salt, one-step enzymatic dyeing, and two-step enzymatic dyeing). Results show that silk dyed with natural dyes by the enzymatic method has higher color strength and colorfastness than the pretreated with a metal salt. Also, the amount of remained dyes in the dyeing wastewater is significantly reduced by the enzymatic method. It is found that the enzymatic dyeing method leads to improvement of dye absorption, color strength, soft hand, no change in color shade, low production costs (due to low dyeing temperature), and a significant reduction in environmental pollution.

Keywords: eco-friendly, natural dyes, silk, traditional dyeing

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Authors: Abhinav Srivastava, Hima Harode, Chandan Kumar Saha

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The principal ingredient of an optical fiber is quartz glass. The quality of the optical fiber decreases if impure foreign substances are attached to its preform surface. If residual strain inside a preform is significant, it cracks with a small impact during drawing or transporting. Furthermore, damages and unevenness on the surface of an optical fiber base material break the fiber during drawing. The present work signifies that chlorine pre-treatment enhances mechanical properties of the optical fiber glass. FTIR (Fourier-Transform Infrared Spectroscopy) results show that chlorine gas chemically modifies the structure of silica clad; chlorine is known to soften glass. Metallic impurities on the preform surface likely formed volatile metal chlorides due to chlorine pretreatment at elevated temperature. The chlorine also acts as a drying agent, and therefore the preform surface is anticipated to be water deficient and supposedly avoids particle adhesion on the glass surface. The Weibull analysis of long length tensile strength demarcates a substantial shift in its knee. The higher dynamic fatigue n-value also indicated surface crack healing.

Keywords: mechanical strength, optical fiber glass, FTIR, Weibull analysis

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Authors: Baba Hassane Ahmed Hisseini, Abdelkrim Bennabi, Rabah Hamzaoui, Lamis Makki, Gaetan Blanck

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Most of the clay soils are known as problematic soils due to their water content, which varies greatly over time. It is observed that they are used to be subject to shrinkage and swelling, thus causing a problem of stability on the structures of civil engineering construction work. They are often excavated and placed in a storage area giving rise to the opening of new quarries. This method has become obsolete today because to protect the environment, we are leading to think differently and opening the way to new research for the improvement of the performance of this type of clay soils to reuse them in the construction field. The solidification and stabilization technique is used to improve the properties of poor quality soils to transform them into materials with a suitable performance for a new use in the civil engineering field rather than to excavate them and store them in the discharge area. In our case, the polymerization method is used for bad clay soils classified as high plasticity soil class A4 according to the French standard NF P11-300, where classical treatment methods with cement or lime are not efficient. Our work concerns clay soil treatment study using raw materials as additives for solidification and stabilization. The geopolymers are synthesized by aluminosilicates materials like fly ash, metakaolin, or blast furnace slag and activated by alkaline solution based on sodium hydroxide (NaOH), sodium silicate (Na2SiO3) or a mixture of both of them. In this study, we present the mechanical properties of the soil clay (A4 type) evolution with geopolymerisation methods treatment. Various mix design of aluminosilicates materials and alkaline solutions were carried at different percentages and different curing times of 1, 7, and 28 days. The compressive strength of the untreated clayey soil could be increased from simple to triple. It is observed that the improvement of compressive strength is associated with a geopolymerization mechanism. The highest compressive strength was found with metakaolin at 28 days.

Keywords: treatment and valorization of clay-soil, solidification and stabilization, alkali-activation of co-product, geopolymerization

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Authors: Constanza Monterrubio-Solis, Jose Tomas Ibarra

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The fertile interdependence of social-ecological systems reveals itself in the interactions between native forests and seeds, home gardens, kitchens, foraging activities, local knowledge, and food practices, creating particular flavors and food meanings as part of cultural identities within territories. Resilience in local-food systems, from a relational perspective, can be understood as the balance between persistence and adaptability to change. Food growing, preparation, and consumption are constantly changing and adapting as expressions of agency of female and male indigenous peoples and peasants. This paper explores local food systems’ expressions of resilience in the la Araucanía region of Chile, namely: diversity, redundancy, buffer capacity, modularity, self-organization, governance, learning, equity, and decision-making. Applying ethnographic research methods (participant observation, focus groups, and semi-structured interviews), this work reflects on the experience developed through work with Mapuche women cultivating home gardens in the region since 2012; it looks to material and symbolic elements of resilience in the local indigenous food systems. Local food systems show indeed indicators of social-ecological resilience. The biocultural memory is expressed in affection to particular flavors and recipes, the cultural importance of seeds and reciprocity networks, as well as an accurate knowledge about the indicators of the seasons and weather, which have allowed local food systems to thrive with a strong cultural foundation. Furthermore, these elements turn into biocultural resistance in the face of the current institutional pressures for rural specialization, processes of cultural assimilation such as agroecosystems and diet homogenization, as well as structural threats towards the diversity and freedom of native seeds. Thus, the resilience-resistance dynamic shown by the social-ecological systems of the southern Andes is daily expressed in the local food systems and flavors and is key for diverse and culturally sound social-ecological health.

Keywords: biocultural heritage, indigenous food systems, social-ecological resilience, southern Andes

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Authors: Amine Rezzoug, Said Abdi, Nadjet Bouhelal, Ismail Daoud

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This paper investigates the application of metallic coatings on high fiber volume fraction carbon/epoxy polymer matrix composites. For the grip of the metallic layer, a method of modifying the surface of the composite by introducing a mixture of copper and steel powder (filler powders) which can reduce the impact of thermal spray particles. The powder was introduced to the surface at the time of the forming. Arc spray was used to project the zinc coating layer. The substrate was grit blasted to avoid poor adherence. The porosity, microstructure, and morphology of layers are characterized by optical microscopy, SEM and image analysis. The samples were studied also in terms of hardness and erosion resistance. This investigation did not reveal any visible evidence damage to the substrates. The hardness of zinc layer was about 25.94 MPa and the porosity was around (∼6.70%). The erosion test showed that the zinc coating improves the resistance to erosion. Based on the results obtained, we can conclude that thermal spraying allows the production of protective coating on PMC. Zinc coating has been identified as a compatible material with the substrate. The filler powders layer protects the substrate from the impact of hot particles and allows avoiding the rupture of brittle carbon fibers.

Keywords: arc spray, coating, composite, erosion

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Authors: Seyed Abolhasan Naeini, Eisa Aliagahei

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Today, the use of geosynthetic materials in geotechnical activities is increasing significantly. One of the main uses of these materials is to increase the compressive strength of clay reinforced by geotextile layers. In the present study, the effect of clay reinforcement by geotextile layers in increasing the compressive strength of clay has been investigated using modeling in ABAQUS 6.11.3 software. For this purpose, the modified Drager Prager model has been chosen to simulate the stress-strain behavior of soil layers and the linear elastic model for the geotextile layer. Unreinforced samples and reinforced samples are modeled by geotextile layers (1, 2 and 3 geotextile layers) by software. In order to validate the results, an article in the same field was used and the numerical modeling results were calibrated with the laboratory results. Based on the obtained results, the software has a suitable capability for modeling and the results of the numerical model overlap with the laboratory results to a very acceptable extent, by increasing the number of geotextile layers, the error between the results of the laboratory sample and the software model increases. The highest amount of error is related to the sample reinforced with three layers of geotextile and is 7.3%.

Keywords: Abaqus, cap model, clay, geotextile layer, reinforced soil

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Authors: Feng-Tsai Weng, Rick Wang, Yan-Cong Liao

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Passivation is a kind of surface treatment for material to reinforce the corrosion resistance specially the stainless alloy. Passive film, is to getting more potential compared to their status before passivation. An oxidation film can be formed on the surface of stainless steel, which has a strong corrosion resistance ability after passivation treatment. In this research, a new passivation technology is proposed for a special stainless alloy which contains a 12-14% Chromium. This method includes the A-A-A (alkaline-acid-alkaline) process basically, which was developed by Carpenter that can neutralize trapped acid. Besides, a corrosion resistant coating layer was obtained by immersing the parts in a water bath of mineral oil at high temperature. Salt spray test ASTM B368 was conducted to investigated performance of corrosion resistant of the passivated stainless steel alloy parts. Results show much better corrosion resistant that followed a coating process after A-A-A Passivation process, than only using A-A-A process. The passivation time is with more than 380 hours of salt spray test ASTM B368, which is equal to 3000 hours of Salt spray test ASTM B117. Proposed passivation method of stainless steel can be completed in about 3 hours.

Keywords: passivation, alkaline-acid-alkaline, stainless steel, salt spray test

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Authors: Chenyu Huang, Minrong Cui, Hua Fang, Luqing Zhang, Yunlong Yu

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The emergence and spread of antibiotic resistance genes (ARGs) have become a pressing issue in global agricultural production. However, understanding how these ARGs spread across different spatial scales, especially when exposed to both pesticides and antibiotics, has remained a challenge. Here, metagenomic assembly and binning methodologies were used to determine the mechanism of ARG propagation within soil-lettuce systems exposed to both fungicides and antibiotics. The results of our study showed that the presence of fungicide and antibiotic stresses had a significant impact on certain bacterial communities. Notably, we observed that ARGs were primarily transferred from the soil to the plant through plasmids. The selective pressure exerted by fungicides and antibiotics contributed to an increase in unique ARGs present on lettuce leaves. Moreover, ARGs located on chromosomes and plasmids followed different transmission patterns. The presence of diverse selective pressures, a result of compound treatments involving antibiotics and fungicides, amplifies this phenomenon. Consequently, there is a higher probability of bacteria developing multi-antibiotic resistance under the combined pressure of fungicides and antibiotics. In summary, our findings highlight that combined fungicide and antibiotic treatments are more likely to drive the acquisition of ARGs within the soil-plant system and may increase the risk of human ingestion.

Keywords: soil-lettuce system, fungicide, antibiotic, ARG, transmission

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Authors: Lakhya Jyoti Basumatary, M. J. Davidson

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Tailor Welded Blanks (TWBs) have established themselves to be a revolutionary and foremost integral part of the automotive and aerospace industries. Metals sheets with varied thickness, strength and coatings are welded together to form TWBs through friction stir welding and laser welding prior to stamping operations. The formability of the TWBs completely varies from those of conventional blanks due to the diverse strength levels of individual sheets which are made to deform under the same forming load uniformly throughout causing unequal and unsatisfactory deformation in the blank. Limiting Dome Height(LDH) test helps predicting the formability of each blanks and assists in determining the appropriate TWB. Finite Element Simulation of LDH test for both base material and TWBs was performed and analysed for both before and after the solution heat treatment. The comparison and validation of simulation results are done with the experimental data and correlated accordingly. The formability of solution heat treated TWBs had enhanced than those of blanks made from non-heat treated TWBs.

Keywords: tailor welded blanks, friction stir welding, limiting dome height test, finite element simulation

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Authors: L. Mouzai, M. Bouhadef

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Raindrops and overland flow both are erosive parameters but they do not act by the same way. The overland flow alone tends to shear the soil horizontally and concentrates into rills. In the presence of rain, the soil particles are removed from the soil surface in the form of a uniform sheet layer. In addition to this, raindrops falling on the flow roughen the water and soil surface depending on the flow depth, and retard the velocity, therefore influence shear velocity and Manning’s factor. To investigate this part, agricultural sandy soil, rainfall simulator and a laboratory soil tray of 0.2x1x3 m were the base of this work. Five overland flow depths of 0; 3.28; 4.28; 5.16; 5.60; 5.80 mm were generated under a rainfall intensity of 217.2 mm/h. Sediment concentration control is based on the proportionality of depth/microtopography. The soil loose is directly related to the presence of rain splash on thin sheet flow. The effect of shear velocity on sediment concentration is limited by the value of 5.28 cm/s. In addition to this, the rain splash reduces the soil roughness by breaking the soil crests. The rainfall intensity is the major factor influencing depth and soil erosion. In the presence of rainfall, the shear velocity of the flow is due to two simultaneous effects. The first, which is horizontal, comes from the flow and the second, vertical, is due to the raindrops.

Keywords: flow resistance, laboratory experiments, rainfall simulator, sediment concentration, shear velocity, soil erosion

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Authors: Maedeh Gharazi

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Adults with age 50 and older will include more than 70% of the diabetic populace by the year 2025. More established patients with diabetes are more inclined to have concurrent ceaseless conditions like hypertension, dyslipidemia, and cardiovascular sickness that may affect their nutritious necessities. The issue of achievement and support of an ideal body weight in elderly diabetic persons may not be as direct as in other age gatherings, and the risk-benefit ratio may be diverse too. Albeit expanded predominance of overweight and weight in the elderly adds to insulin resistance and hyperglycemia, more seasoned tenants of long haul care offices who experience the ill effects of diabetes have a tendency to be underweight. Both may mean insufficient nutritional status and lead to expanded grimness and mortality. The attendant problems of appetite changes, palatability of food, dietary restrictions, loneliness, and depression may influence the sort and amount of food devoured by elderly persons. Organized screening devices may recognize nutrition related issues that warrant proof based mediations. Despite the fact that glucose control and health concerns are essential calculates diet change in the more established populace, different contemplations incorporate personal satisfaction and individual inclinations. Redoing of nutritious rules to the needs of the more seasoned diabetic patient bodes well.

Keywords: diabetes, nutritious necessities, insulin resistance, glucose control

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Authors: Mikael M. Johansson, Peter Stenvall, Leif Karlsson, Joel Andersson

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Sandvik Sanicro 25, UNS S31035, is an advanced high temperature austenitic stainless steel that potentially can be used in super-heaters and reheaters in the next generation of advanced ultra-super critical power plants. The material possesses both high creep strength and good corrosion resistance at temperatures up to 700°C. Its high temperature properties are positioned between other commercially available high temperature austenitic stainless steels and nickel-based alloys. It is, however, well known that an austenitic solidification mode combined with a fully austenitic microstructure exacerbate susceptibility towards hot cracking. The problem increases even more for thick walled material in multipass welding and could compromise the integrity of the welded component. Varestraint weldability testing is commonly used to evaluate susceptibility towards hot cracking of materials. In this paper, Varestraint test results are evaluated for base material of both UNS S31035 steel and are compared to those of the well-known and well-characterized UNS S31008 grade. The more creep resistant alloy, UNS S31035, is metallurgically more complicated than the UNS S31008 grade and has additions of several alloying elements to improve its high temperature properties. It benefits from both solid solution hardening as well as precipitation hardening. This investigation therefore attempts, based on the Varestraint weldability test, to understand if there are any differences in cracking mechanisms between these two grades due to the additional alloying elements used in UNS S31035. Results from Varestraint testing and crack type investigations will be presented and discussed in some detail. It is shown that hot cracking susceptibility of the UNS S31035 steel is only slightly higher than that of UNS S31008 despite the more complicated metallurgy. Weldability of the two alloys is therefore judged to be comparable making the newer alloy well suited also for critical applications.

Keywords: austenitic stainless steel, hot cracking susceptibility, UNS S31035, UNS S31008, varestraint weldability testing

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Authors: Richa Sinha, Mohammad Irfan Javed, Sanjay Singh

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Introduction: Good antimicrobial prescribing reduces length of stay in hospital, risk of adverse events, antimicrobial resistance, and unnecessary hospital expenditure. The aim of this prospective audit was to identify any problems with antimicrobial prescribing including documentation of the relevant aspects as well as appropriateness of antibiotics use. The audit was conducted on the surgical wards in a teaching hospital in the UK. Methods: Standards included the indication, duration, choice, and prescription of antibiotic should be in line with current Regional Guidelines and should be clearly documented on the prescription chart. There should be an entry in each patients’ medical record of the diagnosis and indication for each acute antibiotic prescription issued. All prescriptions should clearly document the route, frequency and dose of antibiotic. Data collection was done for 2 weeks in the month of March 2014. A proforma including all the questions above was completed for all the patients. The results were analysed using Excel. Results: 35 patients in total were selected for the audit. 85.7% of patients had indication of antibiotic documented on the prescription chart and 68.5% of patients had indication documented in the notes. The antibiotic used was in line with hospital guidelines in 45.7% of patients, however, in a further 28.5% of patients the reason for the antibiotic prescription was microbiology approved. Therefore, in total 74.2% of patients had been prescribed appropriate antibiotics. The duration of antibiotic was documented in 68.6% of patients and the antibiotic was reviewed in 37.1% of patients. The dose, frequency and route was documented clearly in 100% of patients. Conclusion: Overall, prescribing can be improved on the surgical wards in this hospital. Only 37.1% of patients had clear documentation of a review of antibiotics. It may be that antibiotics have been reviewed but this should be clearly highlighted on the prescription chart or the notes. Failure to review antibiotics can lead to poor patient care and antimicrobial resistance and therefore it is important to address this. It is also important to address the appropriateness of antibiotics as inappropriate antibiotic prescription can lead to failure of treatment as well as antimicrobial resistance. The good points from the audit was that all patients had clear documentation of dose, route and frequency which is extremely important in the administration of antibiotics. Recommendations from this audit included to emphasize good antimicrobial prescribing at induction (twice yearly), an antimicrobial handbook for junior doctors, and re-audit in 6 months time.

Keywords: prescribing, antimicrobial, indication, duration

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Authors: Touhami Tahenni

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Excessively wide cracks are harmful to the serviceability of reinforced concrete (RC) beams and may lead to durability problems in the longer term. They also reduce the rigidity of RC sections, rendering the tensile concrete ineffective structurally. To reduce the negative effects of cracks, steel fibers are added to concrete mixes in the same manner as aggregates. In the present work, steel fibers reinforced concrete (SFRC) beams, made of normal strength and high strength concretes, were tested in a four-point bending test using a digital image correlation technique. The beams had different volume fractions of fibres and different aspect ratios (fiber length/fiber diameter). The evaluation of flexural cracking widths was determined using Gom-Aramis software. The experimental crack widths were compared with theoretical values predicted by the technical document of Rilem TC 162-TDF. The model proposed in this document seems to be the only one that considers the efficiency of steel fibres in restraining the crack widths. However, the model of Rilem takes into account only the aspect ratio of steel fibres to predict the crack width of SFRC beams. It has been reported in several pieces of research that the contribution of steel fibres to the limitation of flexural cracking widths is based on three essential parameters namely, the volume fraction, the orientation and the aspect ratio of fibres. Referring to the literature on the flexural cracking behavior of SFRC beams and the experimental observations of the present work, a correction of the Rilem model by the introduction of these parameters in the formula is proposed. The crack widths predicted by the new empirical model were compared with the experimental results and assessed against other test data on SFRC beams taken from the literature. The modified Rilem model gives better results and is found more satisfactory in predicting the crack widths of fibres concrete.

Keywords: stee fibres, reinforced concrete, flexural cracking, tensile strength, crack width

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Authors: Weiliang Gong, Lissa Gomes, Lucile Raymond, Hui Xu, Werner Lutze, Ian L. Pegg

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Alkali-activated materials, particularly geopolymers, have attracted much interest in academia. Commercial applications are on the rise, as well. Geopolymers are produced typically by a reaction of one or two aluminosilicates with an alkaline solution at room temperature. Fly ash is an important aluminosilicate source. However, using low-Ca fly ash, the byproduct of burning hard or black coal reacts and sets slowly at room temperature. The development of mechanical durability, e.g., compressive strength, is slow as well. The use of fly ashes with relatively high contents ( > 6%) of unburned carbon, i.e., high loss on ignition (LOI), is particularly disadvantageous as well. This paper will show to what extent these impediments can be mitigated by mixing the fly ash with one or two more aluminosilicate sources. The fly ash used here is generated at the Orlando power plant (Florida, USA). It is low in Ca ( < 1.5% CaO) and has a high LOI of > 6%. The additional aluminosilicate sources are metakaolin and blast furnace slag. Binary fly ash-metakaolin and ternary fly ash-metakaolin-slag geopolymers were prepared. Properties of geopolymer pastes before and after setting have been measured. Fresh mixtures of aluminosilicates with an alkaline solution were studied by Vicat needle penetration, rheology, and isothermal calorimetry up to initial setting and beyond. The hardened geopolymers were investigated by SEM/EDS and the compressive strength was measured. Initial setting (fluid to solid transition) was indicated by a rapid increase in yield stress and plastic viscosity. The rheological times of setting were always smaller than the Vicat times of setting. Both times of setting decreased with increasing replacement of fly ash with blast furnace slag in a ternary fly ash-metakaolin-slag geopolymer system. As expected, setting with only Orlando fly ash was the slowest. Replacing 20% fly ash with metakaolin shortened the set time. Replacing increasing fractions of fly ash in the binary system by blast furnace slag (up to 30%) shortened the time of setting even further. The 28-day compressive strength increased drastically from < 20 MPa to 90 MPa. The most interesting finding relates to the calorimetric measurements. The use of two or three aluminosilicates generated significantly more heat (20 to 65%) than the calculated from the weighted sum of the individual aluminosilicates. This synergetic heat contributes or may be responsible for most of the increase of compressive strength of our binary and ternary geopolymers. The synergetic heat effect may be also related to increased incorporation of calcium in sodium aluminosilicate hydrate to form a hybrid (N,C)A-S-H) gel. The time of setting will be correlated with heat release and maximum heat flow.

Keywords: alkali-activated materials, binary and ternary geopolymers, blends of fly ash, metakaolin and blast furnace slag, rheology, synergetic heats

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Authors: Cedillo Ortiz Cesar Isaac, Marañón-Ruiz Virginia-Francisca, Lozano-Alvarez Juan Antonio, Jáuregui-Rincón Juan, Roger Chiu Zarate

Abstract:

Introduction: The contamination of water with the azo-dye is a problem worldwide as although wastewater contaminate is treated in a municipal sewage system, still contain a considerable amount of dyes. In the present, there are different processes denominated tertiary method in which it is possible to lower the concentration of the dye. One of these methods is by adsorption onto various materials which can be organic or inorganic materials. The xanthan is a biomaterial as removal agents to decrease the dye content in aqueous solution. The Zimm-Bragg model described the experimental isotherms obtained when this biopolymer was used in the removal of textile dyes. Nevertheless, it was not established if a possible correlation between dye structure and removal efficiency exists. In this sense, the principal objective of this report is to propose a qualitative relationship between the structure of three azo-dyes (Congo Red (CR), Methyl Red (MR) and Methyl Orange (MO)) and their removal efficiency from aqueous environment when xanthan are used as dye sequestering agents. Methods: The dyes were subjected to different pH and ionic strength values to obtain the conditions of maximum dye removal. Afterward, these conditions were used to perform the adsorption isotherm as was reported in the previous study in our group. The Zimm-Bragg model was used to describe the experimental data and the parameters of nucleation (Ku) and cooperativity (U) were obtained by optimization using the R statistical software. The spectra from UV-Visible (aqueous solution), Infrared absorption and Raman spectroscopies (dry samples) were obtained from the biopolymer-dye complex. Results: The removal percent with xanthan in each dye are as follows: with CR had 99.98 % when the pH is 12 and ionic strength is 10.12, with MR had 84.79 % when the pH is 9.5 and ionic strength is 43 and finally the MO had 30 % in pH 4 and 72. It can be seen that when xanthan is used to remove the dyes, exists a lower dependence between structure and removal efficiency. This may be due to the different tendency to form aggregates of each dye. This aggregation capacity and the charge of each dye resulting from the pH and ionic strength values of aqueous solutions are key factors in the dye removal. The experimental isotherm of MR was only that adequately described by Zimm-Bragg model. Because with the CR had the 100 % of remove thus is very difficult obtain de experimental isotherm and finally MO had results fluctuating and therefore was impossible get the accurate data. Conclusions: The study of the removal of three dyes with xanthan as dye sequestering agents suggests that aggregation capacity of dyes and the charge resulting from structural characteristics such as molecular weight and functional groups have a relationship with the removal efficiency. Acknowledgements: We are gratefully acknowledged support for this project by Consejo Nacional de Ciencia y Tecnología, México (CONACyT, Grant No. 632694.)

Keywords: adsorption, azo dyes, xanthan gum, Zimm Bragg theory

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