REVIEW | doi:10.20944/preprints202004.0419.v2
Subject: Life Sciences, Biochemistry Keywords: Trichuris trichiura; polymerase chain reaction; bead-beating; DNA extraction; Systematic review
Online: 19 April 2021 (11:54:06 CEST)
Objectives: This meta-analysis was designed to assess the effect of addition of a bead-beating step during DNA extraction to effectively isolate Trichuris trichura DNA for quantitative Polymerase Chain Reaction (qPCR)-based diagnosis. Abstract was reported according to PRISMA-DTA abstract checklist. Methods: Eligibility criteria: qPCR-based molecular studies comparing the inclusion of bead-beating step during the DNA extraction from stool samples with extraction without the step were included in the analysis. Information sources: Studies using real patient samples in community settings were included. PubMed and Google search engine were searched in December 2019. Risk of bias and applicability: Risk of bias and applicability were assessed using QUADAS-2 checklist. Synthesis of results: Odds ratio for individual studies were combined to estimate Random Effects Model odds ratio. Additional literature were searched to discuss biochemical nature of helminth eggs. Results:Included studies: A total of six independent sub-studies were gathered from two published original articles. Division of the two major studies into six sub-studies was indispensable due to natures of the study carried. 128 of total 192 samples (in all studies) were positive for Trichiuris trichiura when bead-beating was used during DNA extraction compared to 108/192 when bead-beating was excluded. Combined odds ratio was 1.66 (95% CI: 1.059 to 2.602). Biochemical nature of helminth eggs was discussed. Discussions: Strengths and limitations: Though only two article were included in the study, six exclusive individual sub-studies were analyzed. Inherent differences in the background prevalence of helminth in study population could impact sensitivity of qPCR. Interpretation: It was found that the inclusion of the bead-beating step during DNA extraction significantly increased the sensitivity of the test.
ARTICLE | doi:10.20944/preprints201801.0133.v1
Subject: Materials Science, Biomaterials Keywords: testosterone; cellulose bead; chitosan; coating; zinc ion; freeze drying; adsorbent
Online: 16 January 2018 (05:04:16 CET)
Immobilized metal ion affinity adsorbents have been widely used in separation technique to purify proteins. Due to the leakage of metal ion from the adsorbents, there is no metal ion affinity adsorbent for hemoperfusion has been applied to clinical trial. In this study, in order to prevent the leakage of Zn2+ loaded from cellulose beads based adsorbent, improve its stability and adsorption capacity for testosterone, Freeze-drying method was used to enhance the porosity of cellulose beads, improve the surface area of the cellulose beads and adsorption capacity for testosterone. Chitosan was used to coat the adsorbents for preventing the leakage of Zn2+ loaded and improve the adsorbent’s stability. Moreover, the factors affecting adsorption ability and some components in plasma were also investigated. The results indicate the adsorption ability of the adsorbent can be significantly improved by freeze-drying. After the adsorbent was coated with 0.02% chitosan solution, the highest adsorption percentage reached 48%. During adsorption, the Zn2+ concentration in plasma did not rise. In addition, the adsorption percentage for total proteins was below 15%. The results may be caused by the pore size and surface area of the adsorbent enlarged via freeze-drying, and the chitosan solution went into the pores and coated the outer and inner surface of the adsorbent. The adsorbent has a potential clinical application to remove testosterone in patients with recurrent and metastatic prostate cancer.
ARTICLE | doi:10.20944/preprints201806.0311.v1
Subject: Engineering, Industrial & Manufacturing Engineering Keywords: laser; welding; LBW; model; microstructure; bead seam; wobble strategy; Inconel 718
Online: 20 June 2018 (05:12:19 CEST)
A numerical model was developed for predicting the bead geometry and microstructure in Laser Beam Welding of 2 mm thickness Inconel 718 sheets. The experiments were carried out with a 1 kW maximum power fiber laser coupled with a galvanometric scanner. Wobble strategy was employed for sweeping 1 mm wide circular areas for creating the weld seams and a specific tooling was manufactured for supplying protective Argon gas during the welding process. The numerical model takes into account both the laser beam absorption and the melt-pool fluid movement along the bead section, resulting in a weld geometry that depends on the process input parameters, such as feed rate and laser power. The microstructure of the beads was also estimated based on the cooling rate of the material. Features as bead upper and bottom final shapes, weld penetration and dendritic arm spacing were numerically and experimentally analyzed and discussed. The results given by the numerical analysis agree with the tests, making the model a robust predictive tool.
ARTICLE | doi:10.20944/preprints202006.0004.v1
Subject: Engineering, Mechanical Engineering Keywords: artificial sand plant; stone crusher; screen unit and sand unit; beating phenomenon; vibration measurement and reduction
Online: 2 June 2020 (09:35:03 CEST)
Due to limitation of natural sand from rivers and seas, artificial sand production from large stones or rocks is being increased. However, this sand manufacturing process is dangerous and causes several social problems such as high level of unwanted vibrations or noises. This study investigates vibration characteristics of sand and screen units in artificial sand production plant whose actuating operation is multiple with several different exciting frequencies. As a first step, vibration levels are measured at the sand and screen unit positions using accelerometers in time and frequency domains. The measurement is carried out at two different conditions: activating sand unit only and operating entire facilities such as stone crusher. Vibration signals acquired from several locations of the sand and screen units of the plant are collected and analyzed from waveforms and spectrums of the signals. It is identified that the vibration acceleration level of the screen unit is higher than that of the sand unit. In addition, it is found from the acceleration signals measured at plant office and shipping control center those places are far away from the plant location that the beating phenomenon is occurred by close driving frequencies for several sand units. In this work, the vibration caused from the beating is significantly reduced by adjusting the driving frequencies for the sand units so that they are sufficiently scattered to avoid the beating.