Meso-scale deformation and damage in thermally bonded nonwovens

Thermal bonding is the fastest and the cheapest technique for manufacturing nonwovens. Understanding mechanical behaviour of these materials, especially related to damage, can aid in design of products containing nonwoven parts. A finite element (FE) model incorporating mechanical properties related to damage such as maximum stress and strain at failure of fabric’s fibres would be a powerful design and optimisation tool. In this study, polypropylene-based thermally bonded nonwovens manufactured at optimal processing conditions were used as a model system. A damage behaviour of the nonwoven fabric is governed by its single-fibre properties, which are obtained by conducting tensile tests over a wide range of strain rates. The fibres for the tests were extracted from the nonwoven fabric in a way that a single bond point was attached at both ends of each fibre. Additionally, similar tests were performed on unprocessed fibres, which form the nonwoven. Those experiments not only provided insight into damage mechanisms of fibres in thermally bonded nonwovens but also demonstrated a significant drop in magnitudes of failure stress and respective strain in fibres due to the bonding process. A novel technique was introduced in this study to develop damage criteria based on the deformation and fracture behaviour of a single fibre in a thermally bonded nonwoven fabric. The damage behaviour of a fibrous network within the thermally bonded fabric was simulated with a FE model consisting of a number of fibres attached to two neighbouring bond points. Additionally, various arrangements of fibres’ orientation and material properties were implemented in the model to analyse the respective effects.     

Factorial Design Optimization of Solid-Phase Microextraction for High-Performance Liquid Chromatography−Ultraviolet Spectrometry Analysis of Polycyclic Aromatic Hydrocarbons in Cigarette Filter Tar

A simple and rapid procedure for the determination of polycyclic aromatic hydrocarbons (PAHs) in cigarette filter tar using solid-phase microextraction (SPME) was developed. The analysis was carried out using high-performance liquid chromatography equipped with an ultraviolet detector. The effects of the SPME experimental parameters on the extraction recovery were studied simultaneously using a central composite design (CCD) after a 2^6?2 fractional factorial experimental design. The SPME variables of interest were the extraction temperature, the extraction time, and the stirring speed, as well as the pH and the concentrations of NaCl (%, w/v) and acetonitrile (ACN). The optimal SPME conditions were as follows: an extraction temperature of 65°C, an extraction time of 50 min, a stirring speed of 800 rpm, 0% NaCl (w/v), 10% ACN in the sample, and a source pH of 8.0. The extraction calibration plots were linear over the range of 0.25?20 ng mL^?1 (r² > 0.9912) and the limits of detection (LODs) for the 6 PAHs studied were from 0.17–5.02 ng cigarette^?1. The relative standard deviation (RSD) ranged from 7.1–13.5% for intra-day variation and from 8.5–18.4% for inter-day variation. The performance of the proposed method was evaluated for extraction and determination PAHs in real samples (various brands of cigarettes). The total amounts of all of the studied PAHs found in the filter tar of the three brands of cigarettes were 320.2, 17.9, and 66.7 ng cigarette^?1, respectively.     

Application of superporous magnetic cationic cryogels for persistent chromate (toxic chromate and dichromate) uptake from aqueous environments

Poly((3‐Acrylamidopropyl)trimethylammonium chloride) (p(APTMACl)) cryogels were prepared with cryopolymerization technique and employed for the removal of toxic chromate and dichromate anions from aqueous media. The maximum adsorption capacities of 94 mg/g and 135 mg/g for chromate and dichromate anions, respectively, were determined with the application of the Langmuir isotherm. These values are very close to the experimental values of about 77 and 128 mg/g from 100 mL, 100 ppm chromate, and dichromate solutions using 0.03 g cryogel. The removal efficiency of chromate and dichromate anions were increased with the increase in the amount of cryogel and the removal percentage of chromate and dichromate toxic anions were estimated as 99.21 and 93.61%, respectively, for 0.15 g of p(APTMACl) cryogels used in 100 mL, 100 ppm chromate, and dichromate solutions. Furthermore, magnetic p(APTMACl) cryogels were also prepared and used in the removal of chromate and dichromate, and the maximum adsorption capacities were 30 mg/g and 40 mg/g, respectively. Additionally, the adsorption of these anions were investigated from different media such as drinking water, tap water, seawater, and creek water; and the maximum adsorption amounts in drinking water were 65.5 ± 15, and 125.5 ± 11 mg/g for chromate and dichromate anions, respectively. The reusability of p(APTMACl) cryogels for the removal of chromate and dichromate anions was also investigated, and it was found that the adsorption capacity for chromate anions decreased to 71.23 ± 4.3 from 97.37 ± 4.5 mg/g, whereas the adsorption capacity of dichromate anions only decreased to 123.69 ± 3.5 mg/g from 129.9 ± 7 mg/g at the end of five adsorption‐desorption cycles. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43438.     

The Scale Effect of Roughness on Hydrodynamic Contact Friction

Multistage abrasive finishing processes (grinding, polishing, honing, etc.) are commonly used to produce the geometrical properties of a surface to meet its technical functionalities in the operating characteristics of contacting parts in friction, relating to their durability and reliability (running-in performance, wear resistance, load-carrying capacity, etc.). Coarse abrasive grits followed progressively finer ones are used, which leads to a multiscale stratified surface texture.

In this article, a numerical model of elastohydrodynamic (EHD) contact coupled to a multiscale surface texture model was developed that allows tracking the scale effect of surface features and their interactions on friction performance and lubricant flow under hydrodynamic lubrication conditions. Because the simulation model has as an input the surface topography and to overcome the variability in surface finish formation, textured surfaces at different stages of the finishing process were simulated (virtual texturing method). Surface topography can be decomposed into two principal components: superficial roughness and valleys. Superficial roughness was modeled using a fractal model and a scaling factor was introduced to model valley patterns. The results show the relationship between friction and surface scales.     

SUPERCRITICAL-DIOXANE EXTRACTION OF TUNCBILEK LIGNITE

ABSTRACT

After preextraction with ethanol-benzene (1:2) in a Soxhlet apparatus Tunçbilek lignite was extracted with dioxane at 330°C in an autoclave at different pressures and for different exposure times. The extracts were fractionated and many of the compounds they contain were identified by gas chromatography/mass spectrometry. The formation and yields of these compounds are discussed in terms of the structure of the parent fuel and the mechanism of extraction.     

Assessment of extensive countrywide electrical power quality measurements through a database architecture

This paper describes countrywide electrical power quality (PQ) assessments of the Turkish Electricity Transmission System through a genuine PQ database. The database stores the output of mobile PQ measurement systems which are established at 172 transformer substations of the transmission system. At 601 measurement points in these substations, which are potentially critical in terms of PQ, measurements are carried out by the mobile systems for a period of 1 week. PQ parameters defined in the IEC-61000-4-30 standard in addition to power values are calculated from acquired raw data by the mobile-monitoring system and the resulting data are transferred to the PQ database. The database, based on a novel PQ data model, enables its users to take PQ snapshots of the transmission system countrywide and can be accessed through several interfaces including a visual query interface, a natural language interface, and a map interface. The overall PQ status of the measured points, representing the characteristics of the transmission system, is assessed through these interfaces and problematic points are determined while deriving important conclusions about the transmission system’s PQ behavior. Moreover, several novel PQ assessment methods are proposed and their applications on the PQ data are demonstrated especially through the map interface.     

Selected Microbiological Properties of Kashar Cheese Samples Preserved with Potassium Sorbate

Kashar cheese, traditionally produced, is a popular dairy product in Turkey. Kashar cheese—a hard cheese—is frequently contaminated with mould. Potassium sorbate can be used for preservation of Kashar cheese. In this article, the effect of potassium sorbate on the microbiological characteristics of Kashar cheese was studied. It was found that the microbial counts at stored at 4 ± 0.1°C for 12 and 24 hours were not different from that of fresh milk samples. The means of total aerobic mesophilic bacteria (TAMB), lactic acid bacteria (LAB), coliforms, Staphylococcus aureus, proteolytic microorganisms, lipolytic bacteria, psychrotrophic bacteria and yeast-moulds in the cheese samples were determined as 4.3 × 10⁷, 2.1 × 10⁵, 3.5 × 10, 1.2 × 10, 4.5 × 10⁵, 5.6 × 10⁴, 1.7 × 10³, and 4.8 × 10⁴ cfu/g, respectively. The addition of potassium sorbate to Kashar cheese decreased the coliform and yeast-mould counts. The yeast and mould counts of cheese samples with added dry potassium sorbate were lower than that of fluid potassium sorbate.     

Acute On‐Chip HIV Detection Through Label‐Free Electrical Sensing of Viral Nano‐Lysate

Development of portable biosensors has broad applications in environmental monitoring, clinical diagnosis, public health, and homeland security. There is an unmet need for pathogen detection at the point‐of‐care (POC) using a fast, sensitive, inexpensive, and easy‐to‐use method that does not require complex infrastructure and well‐trained technicians. For instance, detection of Human Immunodeficiency Virus (HIV‐1) at acute infection stage has been challenging, since current antibody‐based POC technologies are not effective due to low concentration of antibodies. In this study, we demonstrated for the first time a label‐free electrical sensing method that can detect lysed viruses, i.e. viral nano‐lysate, through impedance analysis, offering an alternative technology to the antibody‐based methods such as dipsticks and Enzyme‐linked Immunosorbent Assay (ELISA). The presented method is a broadly applicable platform technology that can potentially be adapted to detect multiple pathogens utilizing impedance spectroscopy for other infectious diseases including herpes, influenza, hepatitis, pox, malaria, and tuberculosis. The presented method offers a rapid and portable tool that can be used as a detection technology at the POC in resource‐constrained settings, as well as hospital and primary care settings.     

Bimetallic nickel-based nanocatalysts for hydrogen generation from aqueous hydrazine borane: Investigation of iron,cobalt and palladium as the second metal

Herein we present and discuss the catalytic activity results of nickel-based bimetallic nanoparticles towards the two-step dehydrogenation of hydrazine borane N₂H₄BH₃. Cobalt, iron and palladium were chosen as the second metal, and a series of Ni_1−xM_x nanocatalysts were prepared by surfactant-aided co-reduction method. The challenge was to find a nanocatalyst that is active in the decomposition of the N₂H₄ moiety of hydrazine borane. Of the 14 Ni_1−xM_x combinations, the best results were achieved with Ni_0.7Fe_0.3 and Ni_0.7Pd_0.3. At 50 °C, 3.9 and 4.3 mol H₂ + N₂ per mole of N₂H₄BH₃ were measured, indicating an activity in the decomposition of the N₂H₄ moiety. Then, both nanocatalysts were characterized by XRD, SEM, EDX, TEM, SAED and XPS. Finally, the differences in catalytic activity were discussed in terms of electronic and geometric effects.