Experimental Study on Warpage Phenomenon of Wax Parts Manufactured by Fused Filament Fabrication.

Warpage is one of the prominent issues in Fused Filament Fabrication. The cause of this is the rapid cooling of the polymer during extrusion. The residual thermal stresses accumulated within the print part result in a shape distortion and subsequent detachment of the object from the print bed. In this study, both experimental and numerical approaches were used to identify the stresses due to thermal shrinking that occurs in soft polymers such as wax. A temperature sweep test was performed using a rotational rheometer to measure the magnitude of axial forces that are generated due to the thermal shrinking of a thin layer of 3D printable wax. The thermal stresses responsible for warpage were computed analytically and using the FEA. It was found that due to thermal processes, the stress magnitude can reach a value of 1.17 MPa. This value is enough to cause the plastic deformation in the wax part having a thin elongated shape. In addition, Taguchi's robust design has identified two major FFF parameters that impact the warpage in amorphous soft polymers. They are the printing speed and the print bed temperature. To achieve a low level of warpage, it is important to make sure that the layer deposition occurs at medium speeds and the print bed temperature is moderately high according to the findings of this study.

Relationship between antimicrobial peptides-induced cell membrane damage and bactericidal activity.

Most antimicrobial peptides (AMPs) act by killing bacterial cells. However, there is little information regarding the required interaction time between AMPs and bacterial cells to exert the bactericidal activity. One of the causes of the bactericidal activity is considered to be cell membrane damage, although little direct evidence is available. Here, we investigated the relationship between AMP-induced cell membrane damage in Escherichia coli and AMP-induced cell death at the single-cell level. Magainin 2, lactoferricin B, and PGLa were selected as the AMPs. First, we examined the interaction time (t) of AMPs with cells required to induce cell death using the single-cell analysis. The fraction of microcolonies containing only a single cell, Psingle (t), which indicates the fraction of dead cells, increased with time to reach ∼1 in a short time (≤5 min). Then, we examined the interaction between AMPs and single cells using confocal laser scanning microscopy in the presence of membrane-impermeable SYTOX green. Within a short time interaction, the fluorescence intensity of the cells due to SYTOX green increased, indicating that AMPs induced cell membrane damage through which the dye entered the cytoplasm. The fraction of cells in which SYTOX green entered the cytoplasm among all examined cells after the interaction time (t), Pentry (t), increased with time, reaching ∼1 in a short time (≤5 min). The values of Psingle (t) and Pentry (t) were similar at t ≥ 3 min for all AMPs. The bindings of AMPs to cells were largely reversible, whereas the AMP-induced cell membrane damages were largely irreversible because SYTOX green entered the cells after dilution of AMP concentration. Based on these results, we conclude that the rapid, substantial membrane permeabilization of cytoplasmic contents after a short interaction time with AMPs and the residual damage after dilution induce cell death.

Analysis of Crystallographic Structures and Properties of Silver Nanoparticles Synthesized Using PKL Extract and Nanoscale Characterization Techniques.

In this cutting-edge research era, silver nanoparticles impose a substantial impact because of their wide applicability in the field of engineering, science, and industry. Regarding the vast applications of silver nanoparticles, in this study, the crystallographic characteristics and nanostructures of silver nanoparticles extracted from natural resources have been studied. First, biosynthetic silver nanoparticles were synthesized using the Pathor Kuchi leaf (PKL) extract as a mediator, and their crystal structures and characteristics were analyzed by UV-visible absorption spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), and energy-dispersive X-ray (EDX) analysis. The average crystallite size of the synthesized silver nanoparticle was determined to be 20.26 nm, and also the lattice strain, intrinsic stress, and dislocation density were measured to be 2.19 × 10-3, 0.08235 GPa, and 3.062045 × 10-3/nm2, respectively. Further, the prepared sample of silver nanoparticles shows four peaks in the X-ray diffraction pattern, which correspond to the (111), (200), (220), and (311) face-centered cubic (FCC) crystalline planes. The outstanding finding of this work was that when the lattice parameters of the precursor were increased, the volume of the material did not considerably change, but the particle size decreased. Second, it was clearly demonstrated that this straightforward method is a clean, cost-effective, environmentally sustainable, nontoxic, and efficient route for the synthesis of silver nanoparticles (Ag NPs) using PKL leaf at ambient temperature, which also satisfies the green chemistry requirements. Finally, this study demonstrates the scope for the production of silver nanoparticles using low-cost natural resources.

Lasia spinosa (L.) thw. attenuates chemically induced behavioral disorders in experimental and computational models.

Lasia spinosa (L.) Thw. (L. spinosa) is widely used as a folk remedy for different physical ailments, and its neurological effects have yet to be assessed. Phytochemicals status of L. spinosa was evaluated by GC-MS analysis. Membrane stabilization test, elevated plus maze (EPM) tests and hole board tests (HBT), tail suspension tests (TST) and thiopental sodium-induced sleeping tests (TISTT) were used to assess anti-inflammatory, anxiolytic and anti-depressant activity. Fourteen compounds have been recorded from GC-MS analysis. The LSCTF showed 68.66 ± 2.46% hemolysis protections (p < 0.05) at 500 µg/mL, whereas LSCHF and LSNHF demonstrated efficiency rates of 68.6 ± 1.46% and 52.46 ± 5.28%, respectively. During EPM tests, LSNHF and LSCTF significantly (p < 0.001) increased the time spent in the open arm (59.88 ± 0.65 s and 50.77 ± 0.67 s, respectively) at the dosages of 400 mg/kg. In HBT, samples exhibited dose-dependent anxiolytic activity. LSNHF and LSCTF showed a significant (p < 0.001) hole poking tendency and a high number of head dips (78.66 ± 1.05 and 65.17 ± 0.96, respectively) at the higher dose. In TST, at 400 mg/kg dose demonstrated significantly (p < 0.001) smaller amounts of time immobile, at 81.33 ± 1.67 s and 83.50 ± 1.90 s, respectively, compared to the control group. A consistent finding was also observed in TISTT. The computer-assisted studies on the identified compounds strongly support the aforementioned biological activities, indicating that L. spinosa has potential as a source of medication for treating neuropsychiatric and inflammatory diseases.

Influence of Mixing Order on the Synthesis of Geopolymer Concrete.

Geopolymers are high-performance, cost-effective materials made from industrial waste that ideally fit the needs of 3D printing technology used in construction. The novelty of the present work lies in the investigation of methods to mix geopolymer concrete from fly ash (FA) class F, ground granulated blast furnace slag (GGBS), and raw calcined kaolin clay (RCKC) to determine the mixing procedure which provides the best mechanical strength and structural integrity. The experimental results show that aluminosilicates with different reaction parameters when mixed one after another provide the optimal results while the geopolymer concrete possesses the highest compressive strength and the denser structure. The results demonstrated that the reactivity of GGBS, FA, and RCKC increased for different depolymerization speeds of the selected aluminosilicates. This research will provide results on how to improve the mixing order for geopolymer synthesis for 3D printing demands. The highest compressive strength and denser structure of geopolymer concrete is achieved when each type of aluminosilicate is mixed with an alkaline medium separately.

COVID-19 diagnostic methods in developing countries.

COVID-19 has become one of the few leading causes of death and has evolved into a pandemic that disrupts everyone's routine, and balanced way of life worldwide, and will continue to do so. To bring an end to this pandemic, scientists had put their all effort into discovering the vaccine for SARS-CoV-2 infection. For their dedication, now, we have a handful of COVID-19 vaccines. Worldwide, millions of people are at risk due to the current pandemic of coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus 2). Despite the lack of clinically authorized antiviral medications and vaccines for COVID-19, clinical trials of many recognized antiviral agents, their combination, and vaccine development in patients with confirmed COVID-19 are still ongoing. This discovery gave us a chance to get immune to this disease worldwide and end the pandemic. However, the unexpected capacity of mutation of the SARS-CoV-2 virus makes it difficult, like the recent SAS-CoV-2 Omicron variant. Therefore, there is a great necessity to spread the vaccination programs and prevent the spread of this dreadful epidemic by identifying and isolating afflicted patients. Furthermore, several COVID-19 tests are thought to be expensive, time-consuming, and require the use of adequately qualified persons to be carried out efficiently. In addition, we also conversed about how the various COVID-19 testing methods can be implemented for the first time in a developing country and their cost-effectiveness, accuracy, human resources requirements, and laboratory facilities.

Microbiome data reveal significant differences in the bacterial diversity in freshwater rohu (Labeo rohita) across the supply chain in Dhaka, Bangladesh.

The present study aimed to characterize and compare the skin and gut microbial communities of rohu at various post-harvest stages of consumption using quantitative real-time polymerase chain reaction and 16S rRNA-based amplicon sequencing. Real-time PCR amplification detected higher copy numbers for coliform bacteria-Escherichia coli, Salmonella enterica and Shigella spp. in the marketed fish-compared to fresh and frozen samples. The 16S rRNA data revealed higher alpha diversity measurements in the skin of fish from different retail markets of Dhaka city. Beta ordination revealed distinct clustering of bacterial OTUs for the skin and gut samples from three different groups. At the phylum level, Proteobacteria was most abundant in all groups except the Fusobacteria in the control fish gut. Although Aeromonas was found ubiquitous in all types of samples, diverse bacterial genera were identified in the marketed fish samples. Nonetheless, low species richness was observed for the frozen fish. Most of the differentially abundant bacteria in the skin samples of marketed fish are opportunistic human pathogens enriched at different stages of postharvest handling and processing. Therefore, considering the microbial contamination in the aquatic environment in Bangladesh, post-harvest handling should be performed with proper methods and care to minimize bacterial transmission into fish.

Elemental Analysis of Basella alba, Spinacia oleracea, Abelmoschus esculentus (L.), Ipomoea aquatica, Colocasia esculenta, Amaranthus dubius, and Raphanus sativus Vegetables Using the PIXE Technique in a Saline Region of Bangladesh, Rampal Area.

Particle-induced X-ray emission (PIXE) method was used in this present research to identify the elements present in selected vegetable samples to show the possible influence in the metal absorption by the vegetables grown in a saline region of Rampal area of Munshiganj District, Bangladesh. The data acquisition setup is calibrated using a 2.5-MeV proton beam in the current ranges of 5nA to 15nA. The detector was used to measure the X-rays emitted during the irradiation. Data acquisition system MAESTRO-32 was used to measure the spectrum picks, and concentration calculation has been done by GUPIX/DAN-32 software. The purpose of this study is to determine the concentration of heavy and trace elements in these samples and to give current information on their safety for consumption. The result shows that K, Ca, and Fe have the highest concentrations, while lead exhibits the lowest but alarming rates compared to reference materials. The findings were likened to IAEA-V-10, IAEA-359, SRM 1515 (apple leaf), and SRM 1573a (tomato leaf). The outcomes of the present investigation demonstrate that these samples are not devoid of health risks in intake.

A Fuzzy Logic-Based Cost Modelling System for Recycling Carbon Fibre Reinforced Composites.

Carbon Fibre Reinforced Polymers (CFRPs) are commonly used materials in manufacturing components and products in the automotive, aerospace, and wind energy industries generating thousands of tons of waste, thus creating a threat to the environment if not recycled. Therefore, it is important for both academia and industry to investigate various ways of recycling this material. However, there is an urgent need for a reliable cost predication system to assist in making informed decisions, planning sustainable treatment, and developing pricing strategies for different waste treatment scenarios. This research paper presents the development of a fuzzy logic-based system to perform cost estimation of recycling processes of the CFRP. The developed system has taken into consideration uncertainties such as the characteristics of End of Life (EoL) material including its size and weight, its origin and diversity of existing recycling methods, and quantity of recycling waste. Cost drivers were divided into categories such as dismantling, transportation, operation, and capital cost. The system was developed by creating 243 fuzzy rules and three levels of fuzzy sets. Moreover, an interactive user-friendly interface was developed to enable the user to use the system easily and efficiently. Finally, case study results were examined to compare the whole life recycling cost of four different recycling technologies in various scenarios of waste treatment. The developed fuzzy logic-based system has the capability in evaluating the cost structure of CFRP recycling techniques and take into consideration uncertainty factors. Hence, a major contribution of the developed system is its provision of the heuristic rules that aid the decision-making process for selecting a cost-effective recycling method. The visualisation facility of the developed system is also a useful tool in enabling potential users to forecast the cost of the CFRP recycling techniques upfront.

Translocation of the nonlabeled antimicrobial peptide PGLa across lipid bilayers and its entry into vesicle lumens without pore formation.

Fluorescent-probe-labeled peptides are used to study the interactions of peptides with cells and lipid vesicles but labeling peptides with fluorescent probes can significantly change these interactions. We recently developed a new method to detect the entry of nonlabeled peptides into the lumen of single giant unilamellar vesicles (GUVs). Here we applied this method to examine the interaction of the antimicrobial peptide PGLa with single GUVs to elucidate whether PGLa can enter the GUV lumen without pore formation. First, we examined the interaction of nonlabeled PGLa with single GUVs comprising dioleoylphosphatidylglycerol (DOPG) and dioleoylphosphatidylcholine (DOPC) (4/6) whose lumens contain the fluorescent probe AF647 and DOPG/DOPC (8/2)-large unilamellar vesicles encapsulating a high concentration of calcein. After a large lag period from starting the interaction with PGLa, the fluorescence intensity of the GUV lumen due to calcein (Icalcein) increased gradually without leakage of AF647, indicating that PGLa enters the GUV lumen without pore formation in the GUV membrane. The fraction of entry of PGLa increased with increasing PGLa concentration. Simultaneous measurement of the fractional area change of the GUV membrane (δ) and PGLa-induced increase in Icalcein showed that the entry of PGLa occurs only during the second increase in δ, indicating that PGLa enters the lumen during its translocation from the outer leaflet to the inner leaflet. The fraction of entry of PGLa without pore formation increased with increasing membrane tension. Based on these results, we discuss the elementary processes and the mechanism of the entry of PGLa into the GUV lumen.

Molecular detection and analysis of virulence genes in multi-drug resistant Escherichia coli from infected broilers.

Escherichia coli associated infections are major threats in poultry industry owing to severe economic losses each year. This study was conducted to identify E. coli isolates, to evaluate their antibiotic sensitivity and to find out their virulence patterns from infected broilers of Sylhet city in Bangladesh. Using polymerase chain reaction, a total 20 isolates were identified as E. coli from 11 chickens, exhibiting symptoms like colibacillosis and/or diarrhea. All isolates were positive for type-1 fimbrial adhesion (fimH), followed by putative avian hemolysin (hlyF) in 17 isolates; while none of the isolates was amplified with intimin (eaeA). Among 10 tested antibiotics, 100% of the isolates (n = 20) showed resistance to ampicillin, amoxicillin and tetra-cycline; but they were 100% sensitive to gentamicin. Organ specific correlations of antibiotic sensitivity were obtained among the isolates through principal component analysis (PCA) and Agglomerative Hierarchical Clustering (AHC). The 16S rRNA data of two multi-drug resistant isolates revealed closed clustering with clinical E. coli strains which could be indication of their zoonotic potential. In conclusion, the results depict higher prevalence of fimH and hlyF genes and drug resistance patterns of E. coli isolates from broilers in Sylhet city of Bangladesh.

Amplicon sequencing reveals significantly increased Vibrio abundance and associated gene functions in vibriosis-infected black tiger shrimp (Penaeus monodon).

Vibriosis caused by luminous Vibrio species is one of the biggest challenges to shrimp industry in Bangladesh. This study aimed to characterize whole microbial communities from Vibrio-infected black tiger shrimp (Penaeus monodon) using 16S rRNA-based amplicon sequencing. A total of 36 disease-free and infected shrimp were collected from six different hatcheries in Bagerhat, Bangladesh. A final pool of 12 samples (n = 6) was created by homogenization of the hepatopancreas samples from three shrimps collected from each hatchery for the same group. The amplicon sequencing data revealed significant (p < .05) decrease of alpha diversity measurements and subsequent effects (p < .05) on the hepatopancreas microbiota in the infected group, compared to control shrimp. Proteobateria and Aeromonas were the most dominant bacteria at phylum and genus level in both groups and identified as core microbiota in the community. Two bacterial groups at phyla level and eight at genus level were found associated with the alteration of hepatopancreas microbial communities and associated gene functions in vibriosis-infected shrimp, revealed by differential abundance and KEGG pathway analysis. The overwhelming abundance of Citroibacter, Shewanella and Candidatus lineages in vibriosis-infected shrimp needs further investigations.

Biological Evaluation, DFT Calculations and Molecular Docking Studies on the Antidepressant and Cytotoxicity Activities of Cycas pectinata Buch.-Ham. Compounds.

Cycas pectinata Buch.-Ham. is commonly used in folk medicine against various disorders. The present study investigated the antidepressant and cytotoxicity activity of methanol extract of C. pectinata (MECP) along with quantitative phytochemical analysis by GC-MS method. Here, the GC-MS study of MECP presented 41 compounds, among which most were fatty acids, esters, terpenoids and oximes. The antidepressant activity was assessed by the forced swimming test (FST) and tail suspension test (TST) models. In contrast, MECP (200 and 400 mg/kg) exhibited a significant and dose-dependent manner reduction in immobility comparable with fluoxetine (10 mg/kg) and phenelzine (20 mg/kg). MECP showed a weak toxicity level in the brine shrimp lethality bioassay (ED50: 358.65 µg/mL) comparable to the standard drug vincristine sulfate (ED50: 2.39 µg/mL). Three compounds from the GC-MS study were subjected to density functional theory (DFT) calculations, where only cyclopentadecanone oxime showed positive and negative active binding sites. Cyclopentadecanone oxime also showed a good binding interaction in suppressing depression disorders by blocking monoamine oxidase and serotonin receptors with better pharmacokinetic and toxicological properties. Overall, the MECP exhibited a significant antidepressant activity with moderate toxicity, which required further advance studies to identify the mechanism.

Molecular characterization and interactome analysis of aerolysin (aer) gene from fish pathogen Aeromonas veronii: The pathogenicity inferred from sequence divergence and linked to histidine kinase (cheA).

Aerolysin (aer) is one of the most important and abundant virulence factors in the infection of fish by Aeromonas veronii. A comprehensive study on the molecular characterization and pathogenicity of the aer gene from 34 A. veronii isolates from diseased carp and catfish was carried out and its interactome was analysed to observe the functional correlations between aer and other proteins within the A. veronii network. The PCR-based amplification of aer from the 34 isolates of A. veronii showed more aer-positive isolates from catfish with a high pathogenic potential in the in vivo challenge test than the carp fish. The analysis of aer gene sequence from challenged fish revealed significant sequence divergence according to the types and geographical distribution of the fish. The networking analysis of aer from the model A. veronii B565 revealed histidine kinase (cheA) as the most functional interacting partner. The study of the interaction between aer from the experimental A. veronii and cheA demonstrated that the A chain of cheA plays a more important role than the corresponding B chain during contact, and a linker sequence of 15 residues controlled the entire interaction process. Therefore, cheA could be an excellent drug target for controlling A. veronii infection of fish.

Targeting of Virulence Factors and Plasmid Profiling of Klebsiella pneumoniae Causing Urinary Tract Infection in Sylhet City of Bangladesh

ABSTRACT Studies were conducted to characterize Klebsiella pneumoniae isolates from urinary tract infection (UTI) patients in Sylhet city of Bangladesh. At the same time, all isolates were screened for some common virulence genes and four significant isolates were searched for plasmid number and sizes by mini alkaline-lysis method. Among five tested isolates from female UTI patients, gyrase subunit B2 (gyrb2) amplified in all isolates, lipase and nuclease detected in three isolates and serine protease amplifies in two isolates and gave the expected band of 1130 bp, 517 bp, 1055 bp and 211 bp respectively. Two of four isolates showed 9.82 kb plasmid band on agarose gel. Isolates bearing 9.82 kb plasmid were found to be resistant to multiple commercial antibiotics. At the same time all isolates were screened for in-vitro plate assay for proteolytic, lypolytic and hemolytic activity. Isolates with positive plasmid and more than one virulent gene with gyrB2 showed positive result in in-vitro culture plate with clear zone of proteolysis, hemolysis or lipolysis. This study will be helpful for further study in finding correlation or pattern of virulence properties for K. pneumoniae associated UTI in Bangladesh.

Anti-inflammatory, anti-diarrheal, thrombolytic and cytotoxic activities of an ornamental medicinal plant: Persicaria orientalis.

BACKGROUND: Persicaria orientalis, an ornamental medicinal plant, has been used in traditional medicine for the treatment of various diseases. Although the plant is reported to have some important pharmacological effects, many medicinal values remain unidentified. Our objective was to evaluate the anti-inflammatory, anti-diarrheal, thrombolytic, and cytotoxic properties of the methanol extract of P. orientalis leaves (Po-MeOH). METHODS: Anti-inflammatory activity was measured by the inhibition of hypotonicity-induced human red blood cell hemolysis and albumin denaturation technique in vitro of Po-MeOH. Diarrheal episodes were examined in mice with castor oil-induced diarrhea. The clot lysis and brine shrimp lethality bioassay in vitro were used to evaluate the thrombolytic and cytotoxic activities of the plant extract, respectively. RESULTS: Using in vitro anti-inflammatory models, the results demonstrated that Po-MeOH at the five different dose ranges from 31.25 to 500 µg/mL significantly (p<0.05) protected (0.98%-50.71%) the erythrocyte membrane against lysis induced by hypotonic medium solution and protein denaturation (38.27%-79.22%) of bovine albumin, respectively. The extract exhibited a significant reduction of severity (75.17%) of castor oil-induced diarrhea in mice at the highest dose of 400 mg/kg compared to loperamide (82.06%) at 5 mg/kg. Po-MeOH also showed 33.14% clot lytic activity in the thrombolytic test and cytotoxicity with LC50 value 58.91 µg/mL in the brine shrimp bioassay. CONCLUSIONS: These findings suggest that Po-MeOH has significant anti-inflammatory and anti-diarrheal effects along with moderate thrombolytic and lower cytotoxic properties that may warrant the further exploration.

Design of potential siRNA molecules for T antigen gene silencing of Merkel Cell Polyomavirus.

Merkel cell carcinoma (MCC) is the most aggressive skin cancer. Recently, it was demonstrated that human Merkel cell polyomavirus (MCV) is clonally integrated in 80% of MCC tumors. Genetic studies of MCV have shown that T antigen protein is responsible for replication of genome and play a foremost role in viral infection. Therefore, T antigen protein may be used as suitable target for disease diagnosis. Viral activity can be restrained through RNA interference (RNAi) technology, an influential method for post transcriptional gene silencing in a sequence specific manner. In current study four effective siRNA molecules for silencing of MCV were rationally designed and validated using computational methods, which may lead to knockdown the activity of virus. Thus, this approach may provide an insight for the chemical synthesis of antiviral RNA molecule for the treatment of MCC at genome level.