Plasma nitriding and duplex coating of biocompatible surfaces for low friction and wear resistant applications

The 316L austenitic stainless steels, Ti-6A1-4V and Ultrahigh molecular weight polyethylene (UHMWP) are very attractive and well known materials for diverse engineering applications due to their many superior properties. More specifically, these materials have acquired much attention in biomedical applications due to their excellent biocompatibility. However, the practical use of these materials are limited in many cases by the need to attain specific tribological (that means, low' friction and wear rate) and mechanical (that means, high hardness, high loadbearing capacity) properties. The long-term outcome of the total joint replacement is currently limited by the breakdown of the implant by wear processes. Therefore, much research has been carried out in this area to reduce the incidence of wear. The goal of this project was to enhance the mechanical and tribological properties of the biocompatible surface by the plasma nitriding and duplex coating process. The works consisted of three phases. In the first phase, in order to acquire a preliminary approximation of the different process parameters, finite volume and finite element methods have been employed to determine (i) the gas mixture pattern inside the sputtering chamber and (ii) the thermal stress inside the coating, with and without considering graded interlaycr respectively. In the second phase of the work, a new plasma nitriding process has been used using an existing carbon based coating system. Plasma nitriding was performed on biomaterials substrates where a Saddle field neutral fast atom beam source and an auxiliary heater was used for substrate heating. It has been observed that low temperature plasma nitriding of the stainless steel samples produced a precipitation and black layer free, hard, thick and load supporting nitridcd layer within a short processing time which was suitable for subsequent coating deposition as well. Plasma nitriding has also been carried out on Ti-6A1-4V and non-conductivc UHMWP biomaterials. In both cases plasma nitriding treatment increased the untreated substrate hardness and wear properties substantially. In the third phase o f the w'ork, the additional improvement of mechanical and tribological properties of the solid lubricant based coatings (MoS2 and DLC), a continuous and discontinuous duplex coating system has been investigated. The main focus has been on the improvement of the load bearing capacity of the coating-substratc system. For the first time a continuous duplex process is being introduced consisting of the plasma nitriding followed by in situ deposition of the DLC biomedical coating. The process has been successfully carried out in a single process chamber (PECVD based Saddle field neutral fast atom beam source) without any interlaycr or post nitriding treatment. Rockwell C indention results confirmed the improvement of the adhesion in the duplex treated coating samples compared to the non-duplex treated sample. Duplex treatment significantly increased the composite hardness and reduced the plastic deformation of the substrate. The Pin on disk tests showed that the duplex treatment increase the overall wear properties of the coating compared to the non-duplex coating. In addition, a discontinuous duplex treatment consisting of plasma nitriding and TiN+MoS, coatings with and without a graded interlaycr on the stainless steel substrate were investigated. Low-temperature plasma nitriding was performed with the newly developed process (Saddle field fast atom beam source) and coatings were deposited by closed-field unbalanced magnetron sputtering. Results showed that the graded interlaycr and plasma nitnding had a great influence on the load bearing and overall tribological properties of the coating-substratc system

Wavelet Based Performance Analysis of Image Compression

In this paper, our aim is to compare for the different wavelet-based image compression techniques. The effects of different wavelet functions filter orders, number of decompositions, image contents and compression ratios were examined. The results of the above techniques WDR, ASWDR, STW, SPIHT, EZW etc., were compared by using the parameters such as PSNR, MSE BPP values from the reconstructed image. These techniques are successfully tested by four different images

Identification of short-length oligonucleotides biomarker for canine species detection using mitochondrial cytochrome b gene

Introduction: Stray dogs are still available in certain countries without any offered price and made it as a potential source for adulteration with costly meats for more benefit. Furthermore, human forensic evidences from crime scenes were often integrated with biomaterial of canine origin. Most of the DNA based assay for canine species detection used longer amplicon size (>150 bp) which are not suitable for highly degraded food or forensic sample analysis. Therefore, in this study for development of short length canine specific biomarker, mitochondrial cytochrome b (cytb) gene was targeted using simple PCR assay. Objective: Detection of canine species using short length DNA biomarker targeting cytb gene. Methods: The assay targeted a 100-bp fragment of cytochrome b gene using a pair of canine specific primers. The primers specificity were tested under Insilco, as well as in real PCR assay using dog and eight other species DNAs. The consensus 100 bp canine specific site along with cytb sequences of 14 species including dog and human were used for analysis of pair wise distances, construct dendogram and primers mismatch calculation. The stability of the biomarker was tested under commonly used cooking condition and extensive autoclaving state which was known for degradation of target DNA. The sensitivity of the assay was tested using binary admixture composed of dog and most consumed chicken DNA pool. Results & Discussion: The biomarker was 100% canine specific and successfully amplified 100 bp region of canine cytb gene specific target. It was highly stable and sensitive enough to detect as low as 0.1% (0.02 ng) of canine specific target from admixed DNAs. Conclusion: The primers provided the shortest DNA biomarker for canine species detection. The shortest amplicon length, high stability and sensitivity offered its potentiality for canine biomaterials determination from food as well as from degraded samples

Prevalence and Therapeutic Efficacy of Anthelmintic against Neoascaris vitulorum in Buffalo Populations from Sylhet District of Bangladesh

Background and Objectives: The epidemiological features of Neoascaris vitulorum infection in buffaloes are important to know their transmission and risk factors assessment as well treatment regimens. This study was conducted with the objectives of determining the prevalence of Neoascaris vitulorum infection in buffaloes in Sylhet district of Bangladesh and to evaluate the efficacy of anthelmintics against the parasite. Materials and Method: A total of 211 fecal samples were collected from buffaloes and examined for the detection of parasitic eggs during the period from July 2017 to June 2018. For the determination of therapeutic efficacy, animals were randomly divided into 6 groups (T0, Ti, T1, T2, T3, T4) where each group consisting of 3 buffaloes. The group T0 (negative control-non infected) and Ti (positive control-infected) were treated only with phosphate buffer saline (PBS). The other four infected groups were treated as T1 with albendazole, T2 with piperazine citrate, T3 with ivermectin and T4 with combination of tetramisole HCL and oxyclosanide. Before trials day 0 and after treatment of 7th, 14th, 21st and 28th days fecal samples examined using McMaster technique. Results: The overall prevalence was estimated 17.06% (36/211). The prevalence was higher among buffalo calves of below six months (39.28%) followed by 6 months to 1 year, 1 to 2 years and above 2 years as 25%, 22.5% and 7.20% respectively. The infection rate was high in females (20.0%) than males (13.18%). The parasite was more prevalent in rainy (21.42%) than summer (16.67%) and winter (14.29%) seasons. The EPG results revealed piperazine citrate was the most effective (100%) against Neoascaris vitulorum. The percent efficacies of other anthelmintic used in this study were albendazole, ivermectin and combination of tetramisole HCL and oxyclozanide as 95.49%, 86.20% and 95.58% respectively. Conclusion: The prevalence of Neoascaris vitulorum infection in buffalo at Sylhet district of Bangladesh was relatively high. The results revealed that piperazine citrate, tetramisole HCL and oxyclozanide combination are highly effective for the reduction of egg per gram (EPG) of Neoascaris vitulorum infection in buffalo. On the other hand ivermectin and albendazole were also around ninety percent effective respectively

A novel catalytic method for the synthesis of spherical aragonite nanoparticles from cockle shells

For the first time, we report here a novel top down catalytic approach for the synthesis of aragonite nanoparticles with spherical morphology from cockleshells. Cockle shell is a natural reservoir of aragonite which is a biogenic polymorph of calcium carbonate. Aragonite polymorph is widely used in the repair of fractured bone, development of advanced drug delivery systems, and tissue scaffolds. The method involves an easily performable and low-cost mechanical stirring of the micron-sized cockle shell powders in presence of a nontoxic biomineralization catalyst, dodecyl dimethyl betaine (BS-12). It produces spherical shaped aragonite nanoparticles of 35 ± 5 nm in diameter with a good reproducibility and without any additional impurities at room temperature. The findings were verified with a variable pressure scanning electron microscopy (VPSEM), energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM),Fourier transmission infrared spectroscopy (FT-IR), X-ray diffractometer (XRD), and thermogravimetric analyzer (TGA).The reproducibility, low-cost and simplicity of the method suggested its potential applications in large scale synthesis of aragonite nanoparticles with spherical morphology in an industrial set up

Cerebral Palsy risk factors associated with pregnancy and delivery

Objective: To identify and analyze the risk factors associated with pregnancy and delivery that contribute to the development of cerebral palsy in children. Material and Methods: To better understand what factors lead to cerebral palsy in children, a cross-sectional study was conducted at the CRP pediatric hospital in Savar, Dhaka. The study's sample size of 56 was reached by a convenience sample of mothers of children with cerebral palsy. In-person interviews were conducted utilizing a survey instrument translated into Bengali or the native tongue and then pilot tested. Excel and SPSS were used for statistical analysis. Informed consent and confidentiality were ensured under ethical guidelines. Results: The data shows past socioeconomic variables. Population age distribution: 37.50% 29–35. 88.1% were Muslim. 59% rural residential areas. 35.70% SSC education.  85.7% had two or more children, 45.6% under three. 55% were males, 45% female. 41% of pregnancies had issues, and 24.9% of women underwent abortions. Normal births were 51.80% and cesarean sections 48.20%. Post-birth statistics included crying immediately (34%), yellowish eyes (50%), fever with seizures (61%), head injuries (48%), and birth hypoxia (38%). 35.70% were born at home, 30.40% in hospitals (17.90% public, 16.10% private). Figure 3 showed hypertension (20%), diabetes (16%), and anemia (23%). Age, religion, education, number of children, past abortions, delivery method, and birthplace were correlated. Diabetes, hypertension, anemia, and birthplace were unrelated. Conclusion: Awareness of cerebral palsy is poor despite its prevalence. In developed country physiotherapy is considered as an important treatment for cerebral palsy children. Quantitative research was used to survey pediatric patients and identify risk variables in this study. Factors shared by many were old age, illiteracy, and origins in rural areas. Risk recognition and mitigation must be prioritized

Screening of commercial meat products from supermarket chains for feline derivatives using SP-PCR-RLFP and lab-on-a-chip

Determination of feline meat in food products is an important issue for social, health, economic and religious concern. Hence this paper documented the application of species specific polymerase chain reaction-restriction fragment length polymorphism (SP-PCR-RFLP) assay targeting a short-fragments (69 bp) of mitochondrial cytochrome b (cytb) gene to screen feline meat in commercial meat products using lab-on-a-chip. The SP-PCR assay proved its specificity theoretically and experimentally while testing with different common animal, aquatic and plant species of DNA. The feline specific (69 bp, 43- and 26-bp) characteristic molecular DNA pattern was observed by SP-PCR and RFLP analysis. For assay performance, it was tested in three different types of commercial dummy meat products such as frankfurters, nuggets and meatballs and digested with AluI-restriction enzyme. The highest sensitivity of the assay using lab-on-a-chip was as low as 0.1 pg or 0.01 % (w/w) in commercial dummy meat products. We have also applied this assay to screen three important commercial meat products of six different brand from six supermarket chains located at three different states of Malaysia. Thus total 378 samples were tested to validate the specificity, sensitivity, stability of the assay and utilization of it for commercial meat product screening

Development of canine biomarker based detection and quantification assays for determining food adulteration and halal authentication / Md. Mahfujur Rahman

The authentication of food product is an important issue to safeguard consumer rights, religious belief, and health and fair-trade economy. Proper labeling of food products allows consumers to make a well-informed purchase decision, commensurations his religious faith, health requirement and of course his personal budget. “Halal” logo on food products reflects both the ingredients and processing steps of the products confirm the Shariah Principles of Islam for hygienic foods. Since halal foods serve the health and religious requirements, their appeal is huge even to the non-Muslim customers. The huge turnover (US$700 billion/ annum) and expanding demands of halal food products testify their widespread popularity throughout the world. The specialized processing, stringent supply chain and safety standard of halal foods have made them costlier to their non-halal counterparts and consequently halal branded products have been targeted for fraud labeling for years. Dog meat consumption is forbidden in Islam and it has been a less discussed issue for fraudulent mixing in halal foods. However, report has been published for the consumption of dog meats by Vietnamese and Myanmarian workers in Malaysia. Dog meat consumptions are also common in South Korea, China and Vietnam. Additionally, the widespread availability of stray dogs without any offered prices in many countries has made it as a highly potential adulterant in halal foods. In literature, five polymerase chain reactions (PCR) assays have been proposed for the detection of dog meats. However, most of the documented assays have targeted longer DNA fragment (≥213 bp) and none of them have tested under complex food matrices. Longer DNA fragments frequently break down during food processing, causing false negative detection in the final assay. To overcome the potential limitations of the existing assays, we have developed short DNA fragment based conventional PCR, PCR-RFLP and real-time PCR assays targeting a 100-bp site of mitochondrial cytochrome b gene. The specificity of the assays were tested using DNA extracted from dog and common meat providing land, aquatic, bird and plant species. The assay stability was tested under different food processing conditions, including boiling, autoclaving and oven heating under pure, admixed and commercial food matrices and was found to be highly stable. The developed conventional PCR assay successfully detected 0.1% to 0.2% (w/w) canine meat from admixed and commercial samples, reflecting its stability and sensitivity under complex matrices. PCR products were authenticated by digesting the product with AluI restriction enzyme which generated 51-, 30- and 19-bp fragments. The digested fragments were successfully separated using Experion Bioanalyzer kit. The sensitivity of the PCR-RFLP assay was 0.0001-ng canine DNA under pure and 0.01% (w/w) canine meat spiked in chicken and beef burger formulations. Finally, a TaqMan probe real-time PCR assay was developed and it was found highly stable and sensitive both under pure and complex matrices. The developed real time-PCR assay successfully detected 0.01% (w/w, 0.002 ng DNA) canine meat spiked in commercial chicken nuggets. A total of six halal branded food products obtained from different Malaysian outlets were screen and no canine adulteration was detected

Impact of training and development on employee performance of a knit garment factory in Bangladesh

Nothing gets done without workers, not even machinery, materials or even money; human resource is the most important asset of any organization. A human being is dynamic; thus employee training and development are vital for maintaining workers on track with the current competitive environment. Employee performance is a key element and the base for improving an organization’s overall success.This thesis aims to examine the effects of training and development on employee performance in a knit garments factory in Bangladesh. The thesis aims to understand the perception of training and development among the employees of the company and the critical factor that influences their performance. For that, questionnaires were distributed among the company's one hundred employees, of which sixty-five responses were collected and analysed. The outcome of the thesis provided an understanding of the effect of training practices in the company and the performance of the employees in terms of problem-solving, facilitation in high workload, workplace safety, and sustainable development. The results are of great importance as they provide empirical evidence which can be used to design strategy to boost the employees’ performance and improve workplace satisfaction

Impact Prediction of Online Education During COVID-19 Using Machine Learning: A Case Study

The transition from traditional to online education is challenging and has many obstacles in various situations. Due to the Covid-19 situation, we use digital blended education from the traditional system. However, in some cases, it can harm our student’s academic performance. In this research, we aim to identify the factors that impact the student’s academic performance in online education. On the other hand, this study also finds the student Cumulative Grade Point Average (CGPA) fluctuation using machine learning classifiers. To achieve this, we survey to gather data perspective of Bangladesh private university, and this data allows us to analyze and classify using machine learning techniques such as Logistic Regression (LR), K-Nearest Neighbor (KNN), Support Vector Machine (SVM), Gaussian Naive Bayes (GNB), Decision Tree (DT), and Random Forest (RF). This study finds Random Forest (RF) outperforms the other state-of-art classifiers