Molecular detection of Brucella melitensis in sheep and goat milk in Iran

Purpose: To detect Brucella melitensis in the milk of reared sheep and goats from Isfahan and Shahrekord regions, Iran. Methods: A total of 225 milk samples (sheep = 125; goat = 100) were collected from Isfahan and Shahrekord regions, Central Iran. Polymerase chain reaction (PCR) was used to detect the presence of B. melitensis in the milk following standard procedures. Results: From 225 milk samples, 20 (8.9 %) were positive for B. melitensis. Out of 125 sheep milk, 12 (9.6 %) had B. melitensis, and of these, 8 (66.6 %) were milk collected from Shahrekord and 4 (33.3 %) from Isfahan region. On the other hand, out of 100 goat milk samples, 18 (18 %) were positive for B. melitensis, out of which 10 (55.5 %) were from Shahrekord and 8 (44.4 %) from Isfahan. Conclusion: The findings show that B. melitensis is present in a significant proportion of caprine and ovine milk in a section of Iran.

Determinantes da fraude financeira : a relação entre os aspectos de racionalidade e a desonestidade

Dissertação (mestrado)—Universidade de Brasília, Universidade Federal da Paraíba, Universidade Federal do Rio Grande do Norte, Programa Multiinstitucional e Inter-regional de Pós-Graduação em Ciências Contábeis, 2016.

Understanding temperature and contact pressure in hot stamped channels

This paper investigates the temperature and contact pressure conditions in hot stamped channels of boron steel. Hot stamping has been used for many years to produce high strength structural auto-motive components. The high tensile strengths achievable by hot stamping is beneficial where the intrusion during a vehicle crash is not desirable – e.g. for the vehicle occupant compartment. How-ever, the high blank temperatures and high temperature cycling causes a large amount of wear in the tooling. These conditions have led to high tool failures and die maintenance costs. Thus, un-derstanding the main causes of wear behaviour in the hot stamping process is of high interest to hot stampers.
To this aim, a generic 2D thermo-mechanical finite element model of a hat-shaped crash formed hot stamped component was developed (based on the authors previous hot stamp model), and a modified phase transformation model based on Scheil’s additive principle has been applied. The model was created in the finite element software ABAQUS Standard V6.13, including convection and radiation when the component was transferred from furnace to the tool as well as the air-cooling process. A USDFLD subroutine was used to model the phase transformation and a HET-VAL subroutine was used to model the latent heat. Contact heat conductance was a function of the pressure.
The authors have used techniques from their previous work on tool wear estimation for cold stamping to estimate the contact pressure on the tooling, and the amount of sliding that occurs over the tooling, and the corresponding tooling temperature. This data provides a unique data set to understand the wear on the tooling, and will eventually lead to a model for estimating tooling life.

The crash behaviour of hot stamped components – the effect of tailoring conditions

It is known that tailoring a hot stamping part, to achieve locally graded properties, can improve the crash behavior. Depending on the role of the structural part (carrying either bending or axial crash load), the best position for the local regions with lower strength and higher ductility can be different. The distribution of these local regions and their mechanical properties affects the crash behavior of the part in each loading case and therefore can be effectively designed to improve the crash performance. To investigate these effects and examine the improvement possibilities, a numerical thermalmechanical-metallurgical model of a hot stamping process and a representative side impact crash model were created and analysed. The hot stamping model was used to predict the consequent phase fractions and mechanical properties of tailored hot stamping parts produced with different tailoring scenarios. In the metallurgical model, a modified phase transformation model based on Scheil’s additive principle was incorporated. The geometry and mesh of the stamped part was exported to a crash numerical model with a 3-point bending configuration. A constitutive model was used to define the plastic behavior of the stamped part corresponding to different hardness values. Various possibilities in locally positioning the high strength or high ductility zones of material were examined. The results show that the positioning of the soft zones has a more significant effect on the crash performance than the variation in their mechanical properties of these soft zones.

Investigation on the effect of cutting fluid pressure on surface quality measurement in high speed thread milling of brass alloy (C3600) and aluminium alloy (5083)

The quality of a machined finish plays a major role in the performance of milling operations, good surface quality can significantly improve fatigue strength, corrosion resistance, or creep behaviour as well as surface friction. In this study, the effect of cutting parameters and cutting fluid pressure on the quality measurement of the surface of the crest for threads milled during high speed milling operations has been scrutinised. Cutting fluid pressure, feed rate and spindle speed were the input parameters whilst minimising surface roughness on the crest of the thread was the target. The experimental study was designed using the Taguchi L32 array. Analysing and modelling the effective parameters were carried out using both a multi-layer perceptron (MLP) and radial basis function (RBF) artificial neural networks (ANNs). These were shown to be highly adept for such tasks. In this paper, the analysis of surface roughness at the crest of the thread in high speed thread milling using a high accuracy optical profile-meter is an original contribution to the literature. The experimental results demonstrated that the surface quality in the crest of the thread was improved by increasing cutting speed, feed rate ranging 0.41-0.45 m/min and cutting fluid pressure ranging 2-3.5 bars. These outcomes characterised the ANN as a promising application for surface profile modelling in precision machining.

Investigation on decomposition behavior of austenite under continuous cooling in vanadium microalloyed steel (30MSV6)

In the present study, investigations are focused on microstructural evolution and the resulting hardness during continuous cooling transformation (CCT) in a commercial vanadium microalloyed steel (30MSV6). Furthermore, the effects of cooling rate and austenite grain size (AGS) on CCT behavior of the steel have been studied by employing high-resolution dilatometry. Quantitative metallography accompanied with scanning electron microscopy (SEM) has efficiently confirmed the dilatometric measurements of transformation kinetics and austenite decomposition products. A semi-empirical model has been proposed for prediction of microstructural development during austenite decomposition of the steel and the resultant hardness. The model consists of 8 sub-models including ferrite transformation start temperature, ferrite growth, pearlite start temperature, pearlite growth, bainite start temperature, bainite growth, martensite start temperature and hardness. The transformed fractions of ferrite, pearlite and bainite have been described using semi-empirical Johnson-Mehl-Avrami-Kolmogorov (JMAK) approach in combination with Scheil's equation of additivity. The JMAK rate parameter for bainite has been formulated using a diffusion-controlled model. Predictions of the proposed model were found to be in close agreement with the experimental measurements.

Wet-spinning of multifunctional graphene fibers using graphene oxide liquid crystals

The recent discovery of liquid crystalline (LC) behavior of graphene oxide (GO) dispersions in various organic, and aqueous media brings added control to the assembly of larger structures using the chemical process approach.[1-3] The LC state can be used to direct the ordered assembly of nanocomponents in macroscopic structures via simple methods like wet-spinning. [3] Here, we developed a scaleable fabrication route to produce graphene fibers via a facile continuoes wetspinning methode. We develop solid understanding in the required criteria to correlate processability with LC behavior, aspect ratio and the dispersion concentration to provide a viable platform for spinning of LC GO. We demonstrate a striking result that highlits the importance of GO sheet size and polydispersity in generating wetspinnable LC GO dispersions from very low spinning dope concentrations (as low as 0.075 wt. %). The new knowledge gained through rheological investigations provides a sound explanation as to why continuous spinning of binder-free GO fibers is enabled by the LC behavior at this very low concentration.

Online stretching of directly electrospun nanofiber yarns

Nanofiber yarns are important building blocks for making three-dimensional nanostructures, e.g. through a knitting or weaving process, with better mechanical properties than nanofiber nonwovens and well-controlled fibrous construction. However, it still remains challenging to produce quality nanofiber yarns in a sufficient rate. In this study, we have proven that online stretching during electrospinning of nanofiber yarns can considerably improve fiber alignment and molecular orientation within the yarn and increase yarn tensile strength, but reduce fiber/yarn diameters. By compensating twist during online stretching, the device can prepare nanofiber yarns with different stretch levels, but maintaining the same twist multiplier. This allows us to examine the effect of stretching on fiber and yarn morphology. It was interesting to find that on increasing the stretching ratio from 0% to 95%, the yarn diameter reduced from 135.1 ± 20.3 μm to 46.2 ± 10.2 μm, and the fiber diameter reduced from 998 ± 141 nm to 631 ± 98 nm, whereas the yarn tensile strength increased from 48.2 ± 5.6 MPa to 127.7 ± 5.4 MPa. Such an advanced yarn electrospinning technique can produce nanofiber yarn with an overall yarn production rate as high as 10 m min−1. This may be useful for production of nanofiber yarns for various applications.

IncSPADE: an incremental sequential pattern mining algorithm based on SPADE property

In this paper we propose Incremental Sequential PAttern Discovery using Equivalence classes (IncSPADE) algorithm to mine the dynamic database without the requirement of re-scanning the database again. In order to evaluate this algorithm, we conducted the experiments against three different artificial datasets. The result shows that IncSPADE outperformed the benchmarked algorithm called SPADE up to 20%.

Novel feature of nano-titanium dioxide on textiles: antifelting and antibacterial wool

In this study, the antifelting and antibacterial features of wool samples treated with nanoparticles of titanium dioxide (TiO2) were evaluated. To examine the antifelting properties of the treated samples, the fabric shrinkage after washing was determined. The antimicrobial activity was assessed through the calculation of bacterial reduction against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) bacteria. TiO 2 was stabilized on the wool fabric surface by means of carboxylic acids, including citric acid (CA) and butane tetracarboxylic acid (BTCA). Both oxidized samples with potassium permanganate and nonoxidized wool fabrics were used in this study. The relations between both the TiO2 and carboxylic acid concentrations in the impregnated bath and the antifelting and antibacterial properties are discussed. With increasing concentration in the impregnated bath, the amount of TiO2 nanoparticles on the surface of the wool increased; subsequently, lower shrinkage and higher antibacterial properties were obtained. The existence of TiO2 nanoparticles on the surface of the treated samples was proven with scanning electron microscopy images and energy-dispersive spectrometry.

Photo induced silver on nano titanium dioxide as an enhanced antimicrobial agent for wool

In this study an effective nanocomposite antimicrobial agent for wool fabric was introduced. The silver loaded nano TiO(2) as a nanocomposite was prepared through UV irradiation in an ultrasonic bath. The nanocomposite was stabilized on the wool fabric surface by using citric acid as a friendly cross-linking agent. The treated wool fabrics indicated an antimicrobial activity against both Staphylococcus aureus and Escherichia coli bacteria. Increasing the concentration of Ag/TiO(2) nanocomposite led to an improvement in antibacterial activities of the treated fabrics. Also increasing the amount of citric acid improved the adsorption of Ag/TiO(2) on the wool fabric surface leading to enhance antibacterial activity. The EDS spectrum, SEM images, and XRD patterns was studied to confirm the presence of existence of nanocomposite on the fabric surface. The role of both cross-linking agent and nanocomposite concentrations on the results was investigated using response surface methodology (RSM).

A survey on mechanisms and critical parameters on solidification of selective laser melting during fabrication of Ti-6Al-4V prosthetic acetabular cup

Additive Manufacturing (AM) includes a range of approaches that correlate with computer aided design (CAD) and manufacturing by fabrication via precise layers and is a promising method for the production of medical tools. In this study, different aspects and mechanisms of solidification for curved surfaces based on equilibrium at curved interfaces, Monge patch, interfacial and Gibbs energy will be discussed. Also, the effect of capillarity, geometry, substrate temperature, cooling rate and scanning parameters in the solidification of a prosthetic acetabular cup (PAC) using selective laser melting (SLM) is analysed. The contributions of this work are analysing solidification and effective factors in this process to produce parts with a higher quality and mechanical properties such as strength, strain, porosity, relative density and hardness. Results indicate that due to the surface to volume (S/V) ratio, and the increasing effect of the radius on Monge patch, thermal stresses and surface forces are more prevalent on outer surfaces. Moreover, solidification and mechanical properties are related to capillarity, geometry, substrate temperature, cooling rate, scanning power and speed. The results also indicate the interaction of solute diffusion and heat transfer with interatomic forces in large S/V ratio and at small scales tend to improve solidification.

An improved static model for tool deflection in machining of Ti–6Al–4V acetabular shell produced by selective laser melting

Tool deflection during milling operation leads to dimensional error, decreasing surface quality and increasing rejection rate. In this study, tool deflection during the milling of the inner surfaces of Ti–6Al–4V prosthetic acetabular shell produced by selective laser melting (SLM) was modelled. The first purpose of this research is to provide a general static cutting tool deflection model for ball nose cutters where deviation of machine components and tool holder are so small as to be considered negligible. This is because the values of machine component and tool holder deflection were lower than standard tolerances (10 μm) and found to be lower than 1/15 of tool deflection. The second and third objectives of this work involve calculating contact surfaces by determining workpiece and tool geometry and choosing second moment of inertia using a novel cross section method (CSM). Static models for three quasi-analytical methods (QAM) that are simple cantilever beam model (SCBM), two-section model (TWSM) and our three section model (THSM) are presented. THSM showed high accuracy which was validated by 3D finite element method (FEM3D) and experimental measurements. The accuracy of tool deflection calculation using THSM by computing, shank, flute and ball head deflection and also utilizing CSM to determine second moment of inertia showed notable improvements.

Evolution of 3D printed soft actuators

Developing soft actuators and sensors by means of 3D printing has become an exciting research area. Compared to conventional methods, 3D printing enables rapid prototyping, custom design, and single-step fabrication of actuators and sensors that have complex structure and high resolution. While 3D printed sensors have been widely reviewed in the literature, 3D printed actuators, on the other hand, have not been adequately reviewed thus far. This paper presents a comprehensive review of the existing 3D printed actuators. First, the common processes used in 3D printing of actuators are reviewed. Next, the existing mechanisms used for stimulating the printed actuators are described. In addition, the materials used to print the actuators are compared. Then, the applications of the printed actuators including soft-manipulation of tissues and organs in biomedicine and fragile agricultural products, regenerative design, smart valves, microfluidic systems, electromechanical switches, smart textiles, and minimally invasive surgical instruments are explained. After that, the reviewed 3D printed actuators are discussed in terms of their advantages and disadvantages considering power density, elasticity, strain, stress, operation voltage, weight, size, response time, controllability, and biocompatibility. Finally, the future directions of 3D printed actuators are discussed.