Confirmatory Test Results Research Articles

Perinatal outcomes following cell-free DNA screening in >32000 women: Clinical follow-up data from a single tertiary center.

Cell-free DNA (cfDNA) screening for aneuploidy was clinically introduced in 2011. We aim to focus on the follow-up information from a single tertiary center undergoing genome-wide cfDNA screening to evaluate this technology. A total of 32431 cases were retrospectively reviewed. The screening was performed using a BGI protocol, and the cfDNA results were analyzed together with the pregnancy outcomes, confirmatory testing results, and ultrasound findings. Of the 32431 cfDNA screening cases, successful follow-up was conducted in 287 (82.2%) cases with high-risk cfDNA results, 85 (94.4%) cases with copy number variation (CNV) and rare autosomal trisomy (RAT) results, and 26060 (81.5%) cases with low-risk cfDNA results. Among them, 234 with high-risk cfDNA results chose invasive testing, revealing 169 true positive cases. In cases with CNV and RAT results, 45 cases underwent invasive diagnosis, revealing six pathogenic CNVs and three uniparental disomies. In cases with low-risk cfDNA results, three false negative cases were confirmed. Cell-free DNA screening appears to be effective in detecting the common autosomal aneuploidies, but one-third of our cohort with high-risk results rejected confirmatory testing. Our data provide information on the clinical experience of large-scale whole-genome cfDNA screening that has global relevance for the implementation of this technology.

Multi response Optimization of Friction stir welding process parameters in dissimilar alloys using Grey relational analysis

A multi response optimization of friction stir welding parameters in dissimilar alloys using Taguchi based Grey relational analysis was studied in this investigation. The dissimilar nonferrous AA8011-H24 aluminium alloys and Ti3Al2.5V titanium alloys were friction stir welded under different process parameters, viz., rotational speed, tool pin profiles and welding speed on tensile strength, tensile elongation and joint efficiency have been optimized by applying multi response analysis. The grey relational grade is attained which correlates between the friction stir welding parameters and responses and the optimum level of welding parameters have been determined by grey analysis. The rotational speed is the most significant contributing parameter to decide the good quality of the welded joints followed welding speed and the tool pin profiles was found using analysis of variance. The confirmation test results showed that the grey relational grade was improved 0.059 with the predicted responses at the optimal conditions.

HIV serology signal-to-cutoff ratio as a rapid method to predict confirmation of HIV infection.

Early and rapid detection of patients with HIV is a key to preventing further transmission. The purpose of this study was to assess the ability of signal-to-cutoff (S/CO) ratio from initial screening fourth-generation HIV serology to predict subsequent confirmation of HIV. Patients with a first-time positive HIV serology (S/CO ratio ≥1) from 2012 to 2016 were included. Ratios were compared to the results of confirmatory testing. Predictive probabilities (PPs) of a positive confirmatory result were calculated based on a logistic regression model. A total of 45,138 HIV serology tests were performed; 250 patients met inclusion criteria, comprising 84 (34%) HIV negative patients, 136 (54%) chronic infections, and 30 (12%) acute infections. The PP of a confirmed positive result increased with higher S/CO ratios, with a PP of 100% for a S/CO of 55 (95% CI 95-100). This study enables a more informed discussion of the probability of HIV infection, based on HIV serology S/CO thresholds, prior to a confirmatory result.

Systematic neonatal screening for congenital Chagas disease in Northeast Brazil: prevalence of Trypanosoma cruzi infection in the Southern region of Sergipe.

Chagas disease is caused by the flagellate protozoan Trypanosoma cruzi, being one of the leading causes of morbidity and mortality in the Americas with an estimated six to seven million infected people worldwide. In Brazil, the improvement in vector control and blood donor screening has evidenced the important epidemiological role of congenital transmission of Chagas disease. A serological survey for Chagas disease was performed in 3,952 newborns in the southern region of Sergipe using paper filter disks of dried blood samples. The newborns were screened using the Sergipe State Neonatal Screening Program between July 2015 and July 2016, and 3,749 and 750 blood samples were obtained for the IgG enzyme-linked immunosorbent assay and indirect immunofluorescence assay, respectively. In addition, mothers of the children who presented initial reagent serology were examined. Among 3,749 blood samples, samples of two children were positive for the enzyme-linked immunosorbent assay; however, their confirmation test results were negative, suggesting passive transfer of the mother's antibody. One puerpera was identified with Chagas disease, with a prevalence of 0.02%. Congenital Chagas disease was not observed in newborns in the Southern region of Sergipe. However, Chagas disease was observed in women of reproductive age. Therefore, effective measurements for monitoring and systematic evaluation should be conducted. The Neonatal Screening Program proved to be an effective public health strategy for the prevention and control of Chagas disease.

Return of test results in Vietnam HIV sentinel surveillance: Implementation and preliminary results

ObjectiveTo describe the implementation and preliminary results of returning HIV test results to participants in Vietnam HIV sentinel surveillance.IntroductionKnowledge of one’s HIV serostatus helps improve quality of life for those who test positive and decreases the risk of HIV transmission. WHO recommends that all participants in HIV prevalence surveys be provided access to their test results, especially those who test HIV positive [1]. Anonymous Vietnam HIV sentinel surveillance (HSS), implemented since 1994, focuses on people who inject drugs (PWID), female sex workers (FSW), and men who have sex with men (MSM) [2]. According to national guidelines, the HIV testing algorithm for surveillance purposes was based on two tests whereas the diagnostic algorithm for individuals was based on three tests. Thus, surveillance test results could not be returned to participants [3] who were instead encouraged to learn their HIV serostatus by testing at public confirmatory testing sites.In 2015, a three-test strategy was applied as part of HSS so that test results could be returned to participants.MethodsIn 2015, return of HIV test results was implemented as a pilot in 16 HSS provinces. HSS participants were asked to identify which of the designated HIV testing and counselling centers (HTC) in the province was most convenient for them. Participants were then given appointment cards with an assigned survey ID to receive their test results at the chosen venue at a specific date and time. Specimens, with assigned survey IDs, were transferred to the respective HIV laboratory at the Province AIDS Center (PAC) for confirmatory testing. The same three-test algorithm was used for surveillance purposes as well as to return confirmatory test results to participants [3]. Final test results were classified as “positive”, “negative” or “indeterminate”. HIV confirmatory test results were made available at all designated HTC in the provinces within 10 days after blood collection; thus, if a participant presented at a location, date or time that differed from the appointment card, s/he could still receive the test result. In some settings in which provinces integrated HSS with either static or mobile HTC, three rapid tests were used at point-of-care so that same-day test results were available. In this case, participants received test results at the end of the specified time regardless of their infection status.At the HTC, individuals showed their appointment cards. The IDs were used to identify the correct test results which were then given verbally to participants by HTC counsellors. Test results were not returned by phone or email. Individuals who tested positive were immediately referred to HIV treatment and other available health/social services in the province.The proportion of participants who received their test results was calculated for each survey group and province.ResultsThe number of provinces that reported returning of HIV test results in 2015 and 2016 were 14 and 15, respectively. Overall, among 15,530 persons tested through HSS in 2015 and 2016, 7,354 persons returned to receive their test results. The proportion of participants who returned for test results varied by province and survey population (table 1). In some provinces where HSS was integrated with HTC, such as Hai Phong and Dong Thap, 100% of participants received their test results within a day [4].ConclusionsReturning HIV test results to HIV surveillance participants is feasible and beneficial in low-income countries like Vietnam. This enhancement facilitates participants learning their serostatus and contributes toward Vietnam’s achievement of HIV control [4]. Based on the pilot experiences, Vietnam Ministry of Health decided to extend test result notifications to all 20 HSS provinces in 2017.Key factors that contributed to the success of the activity were fast turnaround time, roles and level of commitment of PAC, and coordination between the survey and HTC. The returning rate in HSS 2015 and 2016 are promising but these could be improved further. Better coordination and commitment between the survey and HIV testing service are needed to further increase return rates so that HIV-positive individuals can learn their serostatus and be better linked to care and treatment services.

Association Between Early Confirmatory Testing and the Adoption of Active Surveillance for Men With Favorable-risk Prostate Cancer

To examine the relationship between the use and results of early confirmatory testing and persistence on active surveillance (AS). We identified all men in the Michigan Urological Surgery Improvement Collaborative registry diagnosed with favorable-risk prostate cancer from June 2016 to June 2017. We next examined trends in the use of early confirmatory test(s), defined as repeat biopsy, prostate magnetic resonance imaging, or molecular classifiers obtained within 6 months of the initial cancer diagnosis, in patients with favorable-risk prostate cancer. We then compared the proportion of men remaining on AS 6 months after diagnosis according to reassuring vs nonreassuring results, also stratifying by age and Gleason score. Among 2529 patients, 32.7% underwent early confirmatory testing within 6 months of diagnosis. Its use increased from 25.4% in the second quarter of 2016 to 34.9% in the second quarter of 2017 (P = .025). Molecular classifiers were most frequently used (55%), followed by magnetic resonance imaging (34%) and repeat biopsy (11%). Sixty-four percent (n = 523) had a reassuring result. Rates of AS were higher for patients with early reassuring results; 82% remained on AS (n = 427) compared to 52% (n = 157) of those with nonreassuring results and 51% (n = 873) with no early confirmatory testing (P <.001). Rates of AS are higher among men with early reassuring results, supporting the clinical utility of these tests. Nonetheless, high rates of AS among patients with nonreassuring results underscore the complexity of shared decision-making in this setting.

Application of Genetic Algorithm Optimization Technique in TIG Welding of 15CDV6 Aerospace Steel

In this work, an attempt is made to identify the optimized parameter combinations in TIG (Tungsten Inert Gas) welding of 15CDV6 steel. 15CDV6 is a high strength low alloy steel which is widely used in aerospace industries. TIG welding was carried out on 15CDV6 steel with current, voltage, welding speed, shielding gas flow rate as input parameters. Tensile strength, hardness, and corrosion current density were measured as performance characteristics. Artificial Neural Network (ANN) was used as modeling technique for predicting the output parameters. Four different learning algorithms, viz. Batch Back Propagation (BBP), Quick Propagation (QP), Incremental Back Propagation (IBP), Legvenberg- Marquardt (LM) back propagation were used to train the model, and it was found that legvenberg- Marquardt (LM) as the best learning algorithm concerning the prediction accuracy. Genetic algorithm (GA) optimization technique was used to identify the optimized parameter combinations, and a confirmation test was carried out with GA predicted optimized parameters. The confirmation test results were in good agreement with GA results.

Modeling and optimization of face milling process parameters for AISI 4140 steel

In this study, the effect of cutting parameters such as the depth of cut, feed rate, cutting speed and the number of inserts on surface roughness were investigated in the milling of the AISI 4140 steel. The optimal control factors for surface quality were detected by using the Taguchi technique. Experimental trials were designed according to the Taguchi L18 (21x33) orthogonal array. The statistical effects of control factors on surface roughness have been established by using the analysis of variance (ANOVA). Optimal cutting parameters were obtained by using the S/N ratio values. The ANOVA results showed that the effective factors were the number of inserts and the feed rate on surface roughness. However, the depth of cut and the cutting speed showed an insignificant effect. Additionally, the First-order and Second-order regression analysis were conducted to estimate the performance characteristics of the experiment. The acquired regression equation results matched with the surface roughness measurement results. The optimal performance characteristics were obtained as a 0.5 mm depth of cut, 0.08 mm/rev feed rate, 325 m/min cutting speed and 1 number of inserts by using the Taguchi method. Additionally, the confirmation test results indicated that the Taguchi method was very prosperous in the optimization of the machining parameters to obtain the minimum surface roughness in the milling of the AISI 4140 steel.

Comparison and optimization of PVD and CVD method on surface roughness and flank wear in hard-machining of DIN 1.2738 mold steel

PurposeThis paper aims to examine the performance of the machining parameters used in the hard-turning process of DIN 1.2738 mold steel and identify the optimum machining conditions.Design/methodology/approachExperiments were carried out via the Taguchi L18 orthogonal array. The evaluation of the experimental results was based on the signal/noise ratio. The effect levels of the control factors on the surface roughness and flank wear were specified with analysis of variance performed. Two different multiple regression analyses (linear and quadratic) were conducted for the experimental results. A higher correlation coefficient (R2) was obtained with the quadratic regression model, which showed values of 0.97 and 0.95 for Ra and Vb, respectively.FindingsThe experimental results indicated that generally better results were obtained with the TiAlN-coated tools, in respect to both surface roughness and flank wear. The Taguchi analysis found the optimum results for surface roughness to be with the cutting tools of coated carbide using physical vapor deposition (PVD), a cutting speed of 160 m/min and a feed rate of 0.1 mm/rev, and for flank wear, with cutting tools of coated carbide using PVD, a cutting speed of 80 m/min and a feed rate of 0.1 mm/rev. The results of calculations and confirmation tests for Ra were 0.595 and 0.570 µm, respectively, and for the Vb, 0.0244 and 0.0256 mm, respectively. Developed quadratic regression models demonstrated a very good relationship.Originality/valueOptimal parameters for both Ra and Vb were obtained with the TiAlN-coated tool using PVD. Finally, confirmation tests were performed and showed that the optimization had been successfully implemented.

Evaluation of a novel optical assay for rapid detection of methicillin-resistant Staphylococcus aureus in liquid culture

Valid detection of methicillin-resistant Staphylococcus aureus (MRSA) is a precondition for MRSA prevention measures. Most of the available MRSA screening tests are based either on the identification of colony material grown on solid agar media or on direct molecular approaches. The HB&L MRSA KIT (Alifax, Polverara, Italy) is designed to screen for MRSA in liquid cultures applying the light scattering technology. Here, the assay was evaluated with pure culture isolates from solid agar media on a representative subset of 29 MRSA and 171 methicillin-susceptible S. aureus clinical strains from a German multicenter study reflecting the ratio of MRSA to MSSA in Germany. Additionally, 53 mecA/mecC-MRSA comprising hospital-, community and livestock-associated MRSA as well as 20 clinical coagulase-negative staphylococci (CoNS) challenge strains were tested. Including the results of the assay-immanent confirmatory tests for positively tested strains, the sensitivity, specificity and the positive and negative predictive values were 100%. The methicillin-resistance was also correctly identified for all challenge strains.

Is it Feasible to Use an Oral-Fluid Based Rapid Test Facilitated by Frontline Workers to Improve HIV Screening of Pregnant Women in Indian Rural Settings?

Objectives: The importance of knowing HIV status is a key strategy for HIV response and effective treatment services. The present study aimed to assess feasibility of using oral- fluid based rapid HIV test aided by FrontlineHealth workers (FLWs) of pregnant women in rural districts of India. Methods: A feasibility study, using cross sectional design was carried-out in two rural districts of India. Overall, 900 pregnant women were screened using OraQuick® test, an oral-fluid based rapid HIV test facilitated by trained FLWs and subsequently, all participants were tested at in existing government center for confirmatory HIV testing. The data were collected from three aspects: i) the results of OraQuick® HIV test and confirmatory test ii) the perspectives of FLWs through in-depth interviews and iii) information on the acceptability of oral-fluid based HIV testing from 479 pregnant women, through a structured questionnaire. The descriptive statistics was used to analyse the quantitative data and thematic content analysis to analyse the qualitative in-depth interviews. Results: Of the 947 pregnant women who were offered HIV screening using OraQuick® saliva based test, 95% (n=900) accepted to undergo the test. Of the total 479 pregnant women interviewed, 91.2% liked the OraQuick® kit for HIV screening. The key motivators of accepting the test are easy procedure (43%), non-invasiveness (29%) and quick access to results (18%). Out of 900 pregnant women screened by OraQuick®, nine women were found to be HIV positive, which corresponded with confirmatory test results. Qualitative data provided insights into FLWs to understand their views regarding current situation on HIV testing and services available to the pregnant women. Conclusion: With an urgent need to improve access to HIV screening at the grass root level, an oral based HIV rapid testing mechanism can provide a plausible solution for improving early detection of HIV among pregnant women.

Zika Virus Testing and Outcomes during Pregnancy, Florida, USA, 2016.

Zika virus infection during pregnancy can lead to congenital Zika syndrome. Implementation of screening programs and interpretation of test results can be particularly challenging during ongoing local mosquitoborne transmission. We conducted a retrospective chart review of 2,327 pregnant women screened for Zika virus in Miami–Dade County, Florida, USA, during 2016. Of these, 86 had laboratory evidence of Zika virus infection; we describe 2 infants with probable congenital Zika syndrome. Delays in receipt of laboratory test results (median 42 days) occurred during the first month of local transmission. Odds of screening positive for Zika virus were higher for women without health insurance or who did not speak English. Our findings indicate the increase in screening for Zika virus can overwhelm hospital and public health systems, resulting in delayed receipt of results of screening and confirmatory tests and the potential to miss cases or delay diagnoses.

Experimentation on Tool Wear and Surface Roughness in AISI D2 Steel Turning with WC Insert

The Taguchi method, based on an orthogonal arrangement (L9, 33), the vari-ance analysis, the signal-to-noise ratios and the response surface methodol-ogy have been used to optimize maximum flank wear (VBmax) and surface roughness (Ra) of the cutting tool when turning a hardened steel AISI D2 (65 HRC) with PVD—TiAlN coated WC insert upon dry environment. By em-ploying regression models; cutting speed, cutting depth and feed rate, which optimize maximum flank wear and surface roughness were validated. Results of relation signal-to-noise ratios, showed that with cutting speed of 200 m/min, cutting depth of 0.2 mm and feed rate of 0.20 mm/rev, Ra is opti-mized. With cutting speed of 150 m/min, cutting depth of 0.4 mm and feed rate of 0.3 mm/rev, VBmax is optimized. Through the variance analysis it was concluded that the depth of cut was the main parameter that affected on the surface roughness; whereas, the feed rate was the most influential parameter on the flank wear. Confirmation test results showed that the Taguchi method was very successful in the optimization of machining parameters for mini-mum surface roughness and flank wear in the turning of the D2 steel.

Pemeriksaan Escherichia coli, Staphylococcus aureus dan Salmonella sp. pada Jamu Gendong yang Dijajakan di Kota Medan

This study aims to determine the presence of the bacterium Escherichia coli, Staphylococcus aureus and Salmonella sp. in carrying medicinal sold on the five areas in the city of Medan. This study was conducted descriptive of the results of bacterial contamination in carrying medicinal by the number of 20 samples of 5 herbalist carrying in different areas in the city of Medan. The sampling sites are the Menteng area, with a total population carrying medicinal sellers there are 5 people, Literacy area 5, area Tembung 4 people, Sunggal area 3 and area Sei Sekambing 3. Test results Staphylococcus aureus and Salmonella sp. at 5 locations showed negative results and the results of the Total Plate Count 102 at location A (Menteng), namely 3, location B (Traditional), namely 5, the location is C (Tembung) ie 4, the location of D (Sunggal) ie 8 and Area E (Sei Sikambing) is 5. the confirmation test results using BGLB media to determine the negative results (no gas formation) and media testing with Mac-Conkey to grow colonies of pink. On the positive Sunggal local herbal samples contaminated with bacteria coli and other microbial species are not found. This contamination as a result of the manufacturing process that is less attention to elements of sanitation and hygiene as well as the contamination of air at the time of sale and packaging.

Testing lupus anticoagulants in a real-life scenario - a retrospective cohort study.

IntroductionLupus anticoagulant (LAC) testing is challenging. Most data are derived from a well-controlled study environment with potential alterations to daily routines. The aim of this retrospective cohort study was to assess the capacity of various LAC screening tests and derived mixing tests to predict a positive result in subsequent confirmation tests in a large cohort of patients.Materials and methodsIn 5832 individuals, we retrospectively evaluated the accuracy of the aPTT-A, aPTT-LAscreen, aPTT-FS and dRVVTscreen and of their derived mixing tests in detecting a positive confirmation test result within the same blood specimen. The group differences, degree of correlation and the predictive accuracy of LAC coagulation tests were analysed using the Mann-Whitney U test, the Spearman-rank-correlation and by area under the receiver operating characteristic curve (ROC-AUC) analysis. ROC-AUCs were compared with the Venkatraman´s permutation test.ResultsThe pre-test probability of patients with clinically suspected LAC was 36% in patients without factor deficiency or anticoagulation therapy. The aPTT-LAscreen showed the best diagnostic accuracy with a ROC-AUC of 0.84 (95% CI: 0.82 – 0.86). No clear advantage of the dRVVT-derived mixing test was detectable when compared to the dRVVTscreen (P = 0.829). Usage of the index of circulating anticoagulant (ICA) did not improve the diagnostic power of respective mixing tests.ConclusionsAmong the parameters evaluated, aPTT-LAscreen and derived mixing test parameters were the most accurate tests. In our study cohort, neither other mixing test nor the ICA presented any further advantage in LAC diagnostics.

Optimization of fused deposition modeling process parameters using a fuzzy inference system coupled with Taguchi philosophy

Fused deposition modeling (FDM) is an additive manufacturing technique used to fabricate intricate parts in 3D, within the shortest possible time without using tools, dies, fixtures, or human intervention. This article empirically reports the effects of the process parameters, i.e., the layer thickness, raster angle, raster width, air gap, part orientation, and their interactions on the accuracy of the length, width, and thickness, of acrylonitrile-butadiene-styrene (ABSP 400) parts fabricated using the FDM technique. It was found that contraction prevailed along the direction of the length and width, whereas the thickness increased from the desired value of the fabricated part. Optimum parameter settings to minimize the responses, such as the change in length, width, and thickness of the test specimen, have been determined using Taguchi’s parameter design. Because Taguchi’s philosophy fails to obtain uniform optimal factor settings for each response, in this study, a fuzzy inference system combined with the Taguchi philosophy has been adopted to generate a single response from three responses, to reach the specific target values with the overall optimum factor level settings. Further, Taguchi and artificial neural network predictive models are also presented in this study for an accuracy evaluation within the dimensions of the FDM fabricated parts, subjected to various operating conditions. The predicted values obtained from both models are in good agreement with the values from the experiment data, with mean absolute percentage errors of 3.16 and 0.15, respectively. Finally, the confirmatory test results showed an improvement in the multi-response performance index of 0.454 when using the optimal FDM parameters over the initial values.

Modelling and application of response surface optimization to optimize cutting parameters for minimizing cutting forces and surface roughness in high-speed, ball-end milling of Al2014-T6

In this research study, empirical mathematical models for cutting forces and surface roughness have been developed to investigate the effect of axial depth of cut, feed, radial depth of cut and cutting speed in high-speed ball-end milling of Al2014-T6. Ball-end milling experiments have been planned using central composite design based on response surface methodology. The mathematical models have been established and tested for adequacy. A full quadratic model has been adopted for modelling. It has been found that axial depth of cut is the most dominant cutting parameter for the tangential and axial cutting forces, accounting for 49.38 and 47.12% contributions, respectively. Radial depth of cut is the most dominant parameter for radial force and contributes 69.94% for it. Results also revealed that force components decrease with increase in cutting speed. There is very small variation in cutting force components in the cutting speed range of 75–150 m/min at lower values of axial and radial depth of cut. Surface roughness is effected by cutting speed largely followed by feed. Multi-objective optimization has been performed using composite desirability to optimize the cutting parameters for minimum surface roughness and cutting forces simultaneously. Confirmation tests have been conducted using optimal set of cutting parameters. The results of confirmation tests are very close to the predicted results.

The characteristics of screening and confirmatory test results for HIV in Xi'an, China.

ObjectivesIndividuals with recent or acute HIV infection are more infectious than those with established infection. Our objective was to analyze the characteristics of detection among HIV infections in Xi'an.MethodsA 4th-generation kit (Architect HIV Ag/Ab Combo) and three 3rd-generationEIA kits (WanTai, XinChuang and Livzon) were used for HIV screening. Overall, 665 individuals were identified as positive and were tested by western blotting (WB). The characteristics of the screening and confirmatory tests were analyzed, including the band patterns, the early detection performance and the false-positive rates.ResultsIn total, 561 of the 665 patients were confirmed as having HIV-1 infection, and no HIV-2 specific band was observed. Among these 561 WB-positive cases, reactivity to greater than or equal to 9 antigens was the most commonly observed pattern (83.18%), and the absence of reactivity to p17, p31 and gp41 was detected in 6.44%, 5.9% and 2.86% of the cases, respectively. Two cases were positive by the 4th-generation assay but negative by the 3rd-generation assay for HIV screening and had seroconversion. The false-positive rate of the Architect HIV Ag/Ab Combo (22.01%) was significantly higher than those of WanTai (9.88%), XinChuang (10.87%) and Livzon (8.93%), p<0.05.ConclusionHIV infection in Xi'an is mainly caused by HIV-1, and individuals are rarely identified at the early phase. Although the false-positive rate of the 4th-generation assay was higher than that of the 3rd-generation assay, it is still recommended for use as the initial HIV screening test for high-risk individuals. In Xi’an, a 3rd-generation assay for screening could be considered.

Multiobjective optimization of in situ process parameters in preparation of Al-4.5%Cu–TiC MMC using a grey relation based teaching–learning-based optimization algorithm

In modern in situ composite fabrication processes, the selection of optimal process parameters is greatly important for the preparation of best quality metal matrix composite. For achieving high-quality composite, an efficient optimization technique is essential. The present study explores the potential of a new robust algorithm named teaching–learning-based optimization algorithm for in situ process parameter optimization problems in fabrication of Al-4.5%Cu–TiC metal matrix composite fabricated by stir casting technique. Optimization process is carried out for optimizing the in situ processing parameters i.e. pouring temperature, stirring speed, reaction time for achieving better mechanical properties, i.e. better microhardness, toughness, and ultimate tensile strength. Taguchi’s L25 orthogonal array design of experiment was used for performing the experiments. Grey relational analysis is used for the conversion of the multiobjective function into a single objective function, which is being used as the objective function in the teaching–learning-based optimization algorithm. Confirmation test results show that the developed teaching–learning-based optimization model is a very efficient and robust approach for engineering materials process parameter optimization problems.

Evaluation of single and simultaneous thorium and uranium sorption from water systems by an electrospun PVA/SA/PEO/HZSM5 nanofiber

Abstract The performance of poly vinyl alcohol/sodium alginate/poly(ethylene oxide)/HZSM5 (PVA/SA/PEO/HZSM5) nanofiber adsorbent synthesized by electrospinning method for sorption of Th(IV) and U(VI) ions from aqueous systems was investigated in a batch system. The predicted optimum sorption conditions were determined as HZSM5 content of 10 wt%, adsorbent dosage of 1 g/L and initial pH 5.5 by response surface methodology (RSM). The results of experimental confirmation test showed that the predicted model agreed reasonably well with the experimental data. The prepared nanofiber adsorbents were characterized by SEM, FTIR, TGA, BET and BJH analyses. Also, the effects of contact time, initial concentration and temperature were evaluated. The kinetic data of metal ions were well described by the double-exponential model. The maximum sorption capacity of Th(IV) and U(VI) ions were estimated to be 274.6 and 144.7 mg/g, respectively in the single system. Thermodynamic modeling indicated that the nature of both Th(IV) and U(VI) sorption was endothermic and spontaneous and was favored at higher temperature. In binary system, the sorption capacity decreased with increasing another metal ion concentration. The combined effect of metal ions onto the nanofiber was found to be antagonistic. The selectivity order of metal ions sorption onto the adsorbent was Th(IV) > U(VI).