Test Strains Research Articles

The Relationship between Job Strain and Ischemic Heart Disease Mediated by Endothelial Dysfunction Markers and Imaging.

Background and Objectives: Job strain is a psychological, physical, and behavioral stress that occurs at the workplace. Job strain is associated with more than double the normal risk of coronary artery disease (CAD). The main aim of this study was to determine the association between job strain and the following parameters: high-sensitivity C-reactive protein (hs-CRP), the albumin urine excretion rate (AUER), and secondary-level testing. Materials and Methods: This study was a descriptive cross-sectional study conducted on patients who underwent cardiological assessment between October 2023 and February 2024 at the Promedicanon Cardiology Center. This study comprised 210 participants, with two groups: 105 chronic coronary syndromes (CCS) patients and 105 no-CCS patients. The baseline characteristics collected were age, gender, education, rural/urban environment, traditional CAD risk factors, hs-CRP, and AUER. The secondary-level testing included an electrocardiogram (ECG), echocardiography, and enhanced contrast computed tomography (ECCT). Psychological questionnaires comprised the tertiary-level testing, including the PHQ-9 depression questionnaire, and the satisfaction with work scale (SWWS) for job strain (Likert score). Results: The baseline characteristics were all significantly different between the groups (p < 0.05) except for total cholesterol. The hs-CRP level had a mean value of 0.4837 ± 0.19082 in the CCS group; for the no-CCS group, the hs-CRP mean value was 0.2289 ± 0.11009; p-value < 0.001. The AUER had a mean value of 42.770 ± 12.8658 for the CCS group and 26.432 ± 9.7338 for the no-CCS group; p-value < 0.001. For the associations between secondary-level testing and job strain: p < 0.001 for ST depression, negative T-waves, and q-waves; p = 0.415 for atrial fibrillation (AF); p = 0.018 for wall motion studies; p = 0.005 for ECCT. The association between job strain and AF had no statistical significance. The contractility of left ventricle walls and coronary calcification score were associated with job strain, with statistical significance. The p-value was 0.013 for the relationship between depression and the ECCT; for the association between depression and CCS status, the p-value was 0.021. Depression is usually diagnosed in job strain. The association between depression, and coronary calcification, as well as depression and CCS status had statistical significance. Conclusions: Job strain increased the hs-CRP level and AUER in both the CCS and no-CCS patients. The primary and secondary prevention of CHD could also include interventions to reduce job strain.

A panel of genotypically and phenotypically diverse clinical Acinetobacter baumannii strains for novel antibiotic development.

Acinetobacter baumannii is globally notorious, and in an effort to combat the spread of such pathogens, several emerging candidate therapies have already surfaced. However, the strains used to test these therapies vary across studies (the sources and numbers of test strains are varied and often very large, with little heterogeneity). The variation complicates the studies. Furthermore, the limited standardized resources of A. baumannii strains have greatly restricted the research on the physiology, pathogenicity, and antibiotic resistance. Therefore, it is crucial for the research community to acquire a standardized and heterogeneous panel of A. baumannii. Our study meticulously selected 45 diverse A. baumannii strains from a total of 2,197 clinical isolates collected from 64 different hospitals across 27 provinces in China, providing a scientific reference for the research community. This assistance will significantly facilitate scientific exchange in academic research.

Extracellular vesicles released by host epithelial cells during Pseudomonas aeruginosa infection function as homing beacons for neutrophils

BackgroundPseudomonas aeruginosa (PA) is an opportunistic pathogen that can cause sight threatening infections in the eye and fatal infections in the cystic fibrosis airway. Extracellular vesicles (EVs) are released by host cells during infection and by the bacteria themselves; however, there are no studies on the composition and functional role of host-derived EVs during PA infection of the eye or lung. Here we investigated the composition and capacity of EVs released by PA infected epithelial cells to modulate innate immune responses in host cells.MethodsHuman telomerase immortalized corneal epithelial cells (hTCEpi) cells and human telomerase immortalized bronchial epithelial cells (HBECs) were treated with a standard invasive test strain of Pseudomonas aeruginosa, PAO1, for 6 h. Host derived EVs were isolated by qEV size exclusion chromatography. EV proteomic profiles during infection were compared using mass spectrometry and functional studies were carried out using hTCEpi cells, HBECs, differentiated neutrophil-like HL-60 cells, and primary human neutrophils isolated from peripheral blood.ResultsEVs released from PA infected corneal epithelial cells increased pro-inflammatory cytokine production in naïve corneal epithelial cells and induced neutrophil chemotaxis independent of cytokine production. The EVs released from PA infected bronchial epithelial cells were also chemotactic although they failed to induce cytokine secretion from naïve HBECs. At the proteomic level, EVs derived from PA infected corneal epithelial cells exhibited lower complexity compared to bronchial epithelial cells, with the latter having reduced protein expression compared to the non-infected control.ConclusionsThis is the first study to comprehensively profile EVs released by corneal and bronchial epithelial cells during Pseudomonas infection. Together, these findings show that EVs released by PA infected corneal and bronchial epithelial cells function as potent mediators of neutrophil migration, contributing to the exuberant neutrophil response that occurs during infection in these tissues.

Searching for Chemical Agents Suppressing Substrate Microbiota in White-Rot Fungi Large-Scale Cultivation.

Edible fungi are a valuable resource in the search for sustainable solutions to environmental pollution. Their ability to degrade organic pollutants, extract heavy metals, and restore ecological balance has a huge potential for bioremediation. They are also sustainable food resources. Edible fungi (basidiomycetes or fungi from other divisions) represent an underutilized resource in the field of bioremediation. By maximizing their unique capabilities, it is possible to develop innovative approaches for addressing environmental contamination. The aim of the present study was to find selective chemical agents suppressing the growth of microfungi and bacteria, but not suppressing white-rot fungi, in order to perform large-scale cultivation of white-rot fungi in natural unsterile substrates and use it for different purposes. One application could be the preparation of a matrix composed of wooden sleeper (contaminated with PAHs) and soil for further hazardous waste bioremediation using white-rot fungi. In vitro microbiological methods were applied, such as, firstly, compatibility tests between bacteria and white-rot fungi or microfungi, allowing us to evaluate the interaction between different organisms, and secondly, the addition of chemicals on the surface of a Petri dish with a test strain of microorganisms of white-rot fungi, allowing us to determine the impact of chemicals on the growth of organisms. This study shows that white-rot fungi are not compatible to grow with several rhizobacteria or bacteria isolated from soil and bioremediated waste. Therefore, the impact of several inorganic materials, such as lime (hydrated form), charcoal, dolomite powder, ash, gypsum, phosphogypsum, hydrogen peroxide, potassium permanganate, and sodium hydroxide, was evaluated on the growth of microfungi (sixteen strains), white-rot fungi (three strains), and bacteria (nine strains) in vitro. Charcoal, dolomite powder, gypsum, and phosphogypsum did not suppress the growth either of microfungi or of bacteria in the tested substrate, and even acted as promoters of their growth. The effects of the other agents tested were strain dependent. Potassium permanganate could be used for bacteria and Candida spp. growth suppression, but not for other microfungi. Lime showed promising results by suppressing the growth of microfungi and bacteria, but it also suppressed the growth of white-rot fungi. Hydrogen peroxide showed strong suppression of microfungi, and even had a bactericidal effect on some bacteria, but did not have an impact on white-rot fungi. The study highlights the practical utility of using hydrogen peroxide up to 3% as an effective biota-suppressing chemical agent prior to inoculating white-rot fungi in the large-scale bioremediation of polluted substrates, or in the large-scale cultivation for mushroom production as a foodstuff.

Secondary metabolites from Penicillium chrysogenum WX6 and their chemotaxonomic significance

A strain of Penicillium chrysogenum, isolated from a volcanic area, was subjected to chemical analysis, leading to the isolation of fifteen compounds. Six compounds were isolated for the first time from this species, including the benzophenone derivative 1, pencillixanthone A (5), a pair of trichodimerol derivatives (7, 8), 4-epipenicillone (9), and the small pyrone 14. Several of the compounds were tested for antimicrobial properties; among them, the secalonic acid derivative (5) had significant antibacterial activity against five test strains, while the trichodimerol derivatives (8 and 9) and the anthranilate derivative 15 were reported to be active against four strains (S. aureus, S. mutans, P. fluorescens, M. catarrhalis) for the first time. In addition, this is the first time that haenamindole's antibacterial activity has been reported. The chemotaxonomic significance of the isolated compounds is discussed.

Interaction between Steinernema feltiae SC125 and Metarhizium anisopliae sensu lato 9236 for control of the Guatemalan potato moth

ABSTRACT The Guatemalan potato moth (Tecia solanivora) is one of the most destructive pests affecting potatoes in Colombia. Our objective was to evaluate the susceptibility of T. solanivora to a combination of entomopathogenic nematodes and entomopathogenic fungi, to study the interactions of these two agents under laboratory conditions. We evaluated the mortality of fourth instar larvae against 200 Infective Juveniles (IJs) per larva of ten strains of entomopathogenic nematodes, and 104–108 conidia per larva of Beauveria bassiana sensu lato Bb9205 and Metarhizium anisopliae sensu lato Ma9236. We found that Steinernema feltiae SC125 caused a mortality rate of 98.2% with an LC50 of 33 IJs/larva. M. anisopliae sensu lato Ma9236 achieved a mortality rate of 88.8% with an LC50 of 6.9 × 105 conidia/larva. We selected these strains for the interaction tests. We determined that the interaction test results were statistically additive regardless of any difference in application times of the entomopathogens and despite the observation of signs of infection in the hosts from both the nematode and the fungus. Despite not having found synergistic interactions between the evaluated control agents, these laboratory tests suggest a possible strategy of combining entomopathogenic nematode and fungi for biological management of the guatemalan moth T. solanivora in potato crops.

Cofitness network connectivity determines a fuzzy essential zone in open bacterial pangenome.

Most in silico evolutionary studies commonly assumed that core genes are essential for cellular function, while accessory genes are dispensable, particularly in nutrient-rich environments. However, this assumption is seldom tested genetically within the pangenome context. In this study, we conducted a robust pangenomic Tn-seq analysis of fitness genes in a nutrient-rich medium for Sinorhizobium strains with a canonical open pangenome. To evaluate the robustness of fitness category assignment, Tn-seq data for three independent mutant libraries per strain were analyzed by three methods, which indicates that the Hidden Markov Model (HMM)-based method is most robust to variations between mutant libraries and not sensitive to data size, outperforming the Bayesian and Monte Carlo simulation-based methods. Consequently, the HMM method was used to classify the fitness category. Fitness genes, categorized as essential (ES), advantage (GA), and disadvantage (GD) genes for growth, are enriched in core genes, while nonessential genes (NE) are over-represented in accessory genes. Accessory ES/GA genes showed a lower fitness effect than core ES/GA genes. Connectivity degrees in the cofitness network decrease in the order of ES, GD, and GA/NE. In addition to accessory genes, 1599 out of 3284 core genes display differential essentiality across test strains. Within the pangenome core, both shared quasi-essential (ES and GA) and strain-dependent fitness genes are enriched in similar functional categories. Our analysis demonstrates a considerable fuzzy essential zone determined by cofitness connectivity degrees in Sinorhizobium pangenome and highlights the power of the cofitness network in understanding the genetic basis of ever-increasing prokaryotic pangenome data.

Mechanical strength change and coal damage analysis of frozen saturated bitumite after cryogenic freezing

The changes in mechanical strength and damage analysis of bitumite under the action of liquid nitrogen (LN2) freezing are critical issues that need to be addressed in the application of LN2 in coal seam permeability enhancement. Using an MTS testing machine, strain gauges, and ultrasonic detection instruments, experiments were conducted to obtain stress-strain curves and ultrasonic time-domain images of coal samples after single freezing and cyclic freeze-thaw processes. These data were analyzed to understand the mechanical performance and internal fracture evolution of coal samples subjected to ultra-low temperatures of LN2. The experimental results indicate that: (1) the uniaxial compressive strength and elastic modulus of coal samples subjected to a single LN2 freeze are positively correlated with the freezing time from 0 to 50 min, and negatively correlated with the freezing time from 50 to 180 min. (2) The uniaxial compressive strength and elastic modulus of coal samples subjected to cyclic freezing and thawing with LN2 decrease as the number of freeze-thaw cycles increases. (3) The Poisson's ratio of coal samples subjected to single freezing and cyclic freezing-thawing is negatively correlated with the absolute freezing time. Additionally, the decrease in Poisson's ratio is greater in coal samples subjected to cyclic freezing-thawing compared to those subjected to single freezing. (4) As the absolute freezing time increases, the ultrasonic waveforms of the coal samples begin to become disordered, which is manifested by a decrease in amplitude and a delay in the arrival time of the first wave. Under ultra-low temperature conditions, LN2 can deteriorate the mechanical properties of coal samples, with the degree of deterioration being greater under cyclic freezing-thawing than single freezing. This study can provide theoretical guidance for increasing the permeability of coal seams.

A trans-acting sRNA SaaS targeting hilD, cheA and csgA to inhibit biofilm formation of S. Enteritidis

IntroductionSalmonella Enteritidis has brought great harm to public health, animal production and food safety worldwide. The biofilm formed by Salmonella Enteritidis plays a critical role in microbial cross-contamination. Small non-coding RNAs (sRNAs) have been demonstrated to be responsible for regulating the formation of biofilm. The sRNA SaaS has been identified previously, that promotes pathogenicity by regulating invasion and virulence factors. However, whether the SaaS is implicated in regulating biofilm formation in abiotic surfaces remains unclear. ObjectivesThis study aimed to clarify the effect of SaaS in Salmonella Enteritidis and explore the modulatory mechanism on the biofilm formation. MethodsMotility characteristics and total biomass of biofilm of test strains were investigated by the phenotypes in three soft agar plates and crystal violet staining in polystyrene microplates. Studies of microscopic structure and extracellular polymeric substances (EPS) of biofilm on solid surfaces were carried out using confocal laser scanning microscope (CLSM) and Raman spectra. Transcriptomics and proteomics were applied to analyze the changes of gene expression and EPS component. The RNA-protein pull-down and promoter–reporter β-galactosidase activity assays were employed to analyze RNA binding proteins and identify target mRNAs, respectively. ResultsSaaS inhibits biofilm formation by repressing the adhesion potential and the secretion of EPS components. Integration of transcriptomics and proteomics analysis revealed that SaaS strengthened the expression of the flagellar synthesis system and downregulated the expression of curli amyloid fibers. Furthermore, RNA-protein pull-down interactome datasets indicated that SaaS binds to Hfq (an RNA molecular chaperone protein, known as a host factor for phage Qbeta RNA replication) uniquely among 193 candidate proteins, and promoter–reporter β-galactosidase activity assay confirmed target mRNAs including hilD, cheA, and csgA. ConclusionSaaS inhibits the properties of bacterial mobility, perturbs the secretion of EPS, and contributes to the inhibition of biofilm formation by interacting with target mRNA (hilD, cheA, and csgA) through the Hfq-mediated pathway.

Inverted amino acids reduce the adhesion and biofilm biomass of early oral colonizers.

Early colonizers adhere to the dental surface and facilitate the initial adhesion of secondary colonizers to form oral biofilms, which may cause oral infections. This study aimed to determine the antimicrobial, anti-adhesion and antibiofilm potency of inverted amino acids on early colonizer streptococci and their mixed species. The following test strains were used: Streptococcus gordonii (American Type Culture Collection (ATCC) 35105); Streptococcus mitis (ATCC 49456); Streptococcus oralis (ATCC 10557); Streptococcus salivarius (ATCC 7073); and Streptococcus sanguinis (ATCC BAA-1455). The concentration-dependent antimicrobial potency of d-alanine (d-ala), d-arginine (d-arg), d-leucine (d-leu), d-methionine (d-met), and d-tryptophan (d-try) was determined using the Clinical and Laboratory Standards Institute (CLSI) broth microdilution method with AlamarBlue modification. The adhesion of primary colonizers in the presence of 25-mM d-amino acids (dAAs) was assessed using the colony forming unit (CFU) assay. The CFU assay was conducted on 24-h flow cell bacterial biofilm models after exposure to 25-mM inverted dAAs. No minimum inhibitory concentration (MIC) point was detected at any concentration tested. The minimum bactericidal concentration (MBC) point was not observed. The adhesion of S. mitis, S. oralis and mixed species was reduced by all tested dAAs. No adverse effects were observed on S. gordonii with any of the tested dAAs. The biofilm biomass of test strains under flow conditions was significantly reduced after a 5-min exposure to all tested dAAs at 25-mM concentration. D-amino acids did not inhibit bacterial growth and did not show bactericidal or bacteriostatic effects on test strains at any concentration tested (ranging from 6.25 mM to 100 mM). However, dAAs effectively inhibit the adhesion of early colonizers, thereby preventing the formation of oral biofilm.

Screening of plant growth-promoting rhizobacteria helps alleviate the joint toxicity of PVC+Cd pollution in sorghum plants

Combined microplastic and heavy metal pollution (CM-HP) has become a popular research topic due to the ability of these pollutants to have complex interactions. Plant growth-promoting rhizobacteria (PGPR) are widely used to alleviate stress from heavy metal pollution in plants. However, the effects and mechanisms by which these bacteria interact under CM-HP have not been extensively studied. In this study, we isolated and screened PGPR from CM-HP soils and analyzed the effects of these PGPR on sorghum growth and Cd accumulation under combined PVC+Cd pollution through pot experiments. The results showed that the length and biomass of sorghum plants grown in PVC+Cd contaminated soil were significantly lower than those grown in soils contaminated with Cd alone, revealing an enhancement in toxicity when the two contaminants were mixed. Seven isolated and screened PGPR strains effectively alleviated stress due to PVC+Cd contamination, which resulted in a significant enhancement in sorghum biomass. PGPR mitigated the decrease in soil available potassium, available phosphorus and alkali-hydrolyzable nitrogen content caused by combined PVC+Cd pollution and increased the contents of these soil nutrients. Soil treatment with combined PVC+Cd pollution and PGPR inoculation can affect rhizosphere bacterial communities and change the composition of dominant populations, such as Proteobacteria, Firmicutes, and Actinobacteria. PICRUSt2 functional profile prediction revealed that combined PVC+Cd pollution and PGPR inoculation affected nitrogen fixation, nitrification, denitrification, organic phosphorus mineralization, inorganic phosphorus solubilization and the composition and abundance of genes related the N and P cycles. The Mantel test showed that functional strain abundance, the diversity index and N and P cycling-related genes were affected by test strain inoculation and were significant factors affecting sorghum growth, Cd content and accumulation. This study revealed that soil inoculation with isolated and screened PGPR can affect the soil inorganic nutrient content and bacterial community composition, thereby alleviating the stress caused by CM-HP and providing a theoretical basis and data support for the remediation of CM-HP.

The impact of chewing force simulation on stress distribution of implant retained mandibular overdenture with locator attachment system having matrix of PEEK versus nylon insert

The current study investigates the impact of chewing force simulation on stress strain distribution of Mandibular overdentures retained with locator attachment system having matrix of PEEK versus nylon insert. Twenty completely edentulous mandibular digitally printed models were fabricated with beds for two implants, which had been inserted in the estimated canine positions with two grooves mesial and distal at each implant site for the attachment of the strain gauges for each model. Nova loc group NLG with ten implant assisted mandibular complete overdentures were fabricated over ten printed models with nova loc attachments while locator group LG had ten implant assisted mandibular complete overdentures over ten printed models with locator attachments of same retaining force and geometric height. Bilateral vertical load was applied with a universal testing machine and strain induced to the implants was measured around the two implants medially and distally in each group using strain gauges pre &amp; post one year simulated functional aging. Student t test was used for comparing the two types of attachments while paired t test was used for comparison of strain induced to the implants after one year of functional aging, with probability level p &lt; 0.05 is considered statistically significant. Individual statistical analysis of the data revealed increase in the number of measured strains for both attachments which was statistically significant for locator. Comparing the two groups, significant increase for the locator attachment after one year simulated functional aging was detected compared to nova loc. Within the limitations of this study, one year simulated functional aging seems to cause disturbance in the load conveyed to the supporting structures of mandibular implant assisted overdenture retained with locator in contrast to nova loc that showed more resistance to aging process, thus nova loc attachment transmit less stresses than locator attachment to the surrounding implants supporting structures specially after time of service related to its combined materials superior physical properties.

Biodegradation and antimicrobial capability-induced heavy metal resistance of the marine-derived actinomycetes Nocardia harenae JJB5 and Amycolatopsis marina JJB11.

Currently, heavy metal-resistant (HMR) marine actinomycetes have attracted much attention worldwide due to their unique capabilities. In this study, 27 marine-derived actinomycetes were isolated from coastal beaches in the Arabian Gulf of Al-Jubail in Saudi Arabia and screened for resistance to 100 mg/L of the heavy metals Cd2+, Cr6+, Cu2+, Fe2+, Pb2+, and Ni2+ using different assay techniques. Six isolates were selected as HMRs, of which two isolates, JJB5 and JJB11, exhibited the highest maximum tolerance concentrations (200- > 300 mg/L). Both isolates were the highest among six-HMR screened for their biodegradation potential of plastics low-density polyethylene, polystyrene, and polyvinyl chloride, recording the highest weight loss (15 ± 1.22 - 65 ± 1.2%) in their thin films. They also showed the highest biodegradability of the pesticides acetamiprid, chlordane, hexachlorocyclohexane, indoxacarb and lindane, indicating promising removal capacities (95.70-100%) for acetamiprid and indoxacarb using HPLC analysis. Additionally, the cell-free filtrate (CFF) of both isolates displayed the highest antimicrobial activity among the six-HMR screened against a variety of microbial test strains, recording the highest inhibition zone diameters (13.76 ± 0.66 - 26.0 ± 1.13 mm). GC‒MS analyses of the ethyl acetate extract of their CFFs revealed the presence of diverse chemical compounds with a multitude of remarkable biological activities. Based on their spore morphology and wall-chemotype, they were assigned to the nocardioform-actinomycetes. Furthermore, their phenotypic characteristics, together with 16S rRNA gene sequencing (OR121525-OR121526), revealed them as Nocardia harenae JJB5 and Amycolatopsis marina JJB11. Our results suggest that marine HMR actinomycetes are promising candidates for various biotechnological applications.

Effect of limited proteolysis and CaCl2 on the rheology, microstructure and in vitro digestibility of pea protein-carboxymethyl cellulose mixed gel

Limited proteolysis, CaCl2 and carboxymethyl cellulose (CMC) have individually demonstrated ability to increase the gel strength of laboratory-extracted plant proteins. However, the syneresis effects of their combination on the gelling capacity of commercial plant protein remains unclear. This was investigated by measuring the rheological property, microstructure and protein–protein interactions of gels formed from Alcalase hydrolyzed or intact pea proteins in the presence of 0.1 % CMC and 0–25 mM CaCl2. Sodium dodecyl-sulfate polyacrylamide gel electrophoresis (SDS-PAGE) showed the molecular weight of pea protein in the mixture were < 15 kDa after hydrolysis. The hydrolysates showed higher intrinsic fluorescence intensity and lower surface hydrophobicity than the intact proteins. Rheology showed that the storage modulus (G') of hydrolyzed pea protein (PPH)-based gels sightly decreased compared to those of native proteins. 5–15 mM CaCl2 increased the G’ for both PP and PPH-based gels and decreased the strain in the creep-recovery test. Scanning electron microscopy (SEM) showed the presence of smaller protein aggregates in the PPH-based gels compared to PP gels and the gel network became denser, and more compact and heterogenous in the presence of 15 and 25 mM CaCl2. The gel dissociation assay revealed that hydrophobic interactions and hydrogen bonds were the dominant forces to maintain the gel structure. In vitro digestion showed that the soluble protein content in PPH-based gels was 10 ∼ 30 % higher compared to those of the PP counterpart. CaCl2 addition reduced protein digestibility with a concentration dependent behavior. The results obtained show contrasting effects of limited proteolysis and CaCl2 on the gelling capacity and digestibility of commercial pea proteins. These findings offer practical guidelines for developing pea protein-based food products with a balanced texture and protein nutrition through formulation and enzymatic pre-treatment.

Assessment of the effect of using immunomodulatory drugs for emergency prevention of experimental plague caused by a virulent strain of the main subspecies Yersinia pestis

Introduction. Immunomodulatory drugs (IMD) have great potential to increase the nonspecific reactivity of the organism in a set of measures for emergency prevention of plague. The purpose of the work is to evaluate the protective effectiveness of the use of IMD of different groups in experiments on modeling infection with a highly virulent strain of the plague microbe. Materials and methods. IMD (rIFN-γ — recombinant interferon-gamma, PO — azoximer bromide, synthetic immunomodulatory oligopeptides O1, O2, O3) was administered to white mice and guinea pigs subcutaneously thrice by the schedule 3 days, 1 day, and 1 hour prior the infection with a virulent test strain of plague Yersinia pestis 231 (708) at dose from 1 to 625 CFU. In addition, the effect of IMD on the production of IFN-γ and interleukin-10 was investigated in white mice before infection. Results. The study of the effect of IMD on the survival of unvaccinated biomodels made it possible to establish that only rIFN-γ and PO increase the survival of two types of laboratory animals by 20–50% and significantly increase the LD50. All tested IMD contribute to an increase in the average life expectancy of biomodels by at least one day. An increase in spontaneous and mitogen-induced cytokine production was found only in white mice receiving rIFN-γ and PO, which correlates with animal survival rates. Conclusion. The obtained data indicate the effectiveness of the use of IMD, especially rIFN-γ and PO in protecting the macroorganisms from infection with Y. pestis, which determines the prospects for research on the further improvement of emergency prevention of plague.

Dynamic tensile behaviour of 7A04-T6 aluminium alloy at elevated temperatures

As typical light engineering metals, aluminium alloys are widely employed in modern manufacturing and construction sectors. Among them, 7A04-T6 high-strength aluminium alloy (AA7A04-T6), alloying with Zn, Mg and Cu and manufactured via the T6 temper process, is a good alternative to steel in construction and is now attractive to engineers and researchers. The structural members made from 7A04-T6 High-strength aluminium alloy are also vulnerable to a variety of accidental actions, such as impact and blast which expose the AA7A04-T6 material to both high strain rates and elevated temperature. To date, investigations into the mechanical properties of AA7A04-T6 material under the loading conditions with strain rates and temperatures coupled are still limited. Dynamic tensile tests were conducted under the rate-temperature coupling test conditions in this work, to study the influence of strain rate and temperature on the stress-strain response of AA7A04-T6 material. The ranges of the test strain rate and temperature were from 0.001 s−1 to 102 s−1 and from 20 ℃ to 200 ℃, respectively. Based on the classical Johnson-Cook model and Cowper-Symonds model, a modified model was proposed for AA7A04-T6 material and good agreement is achieved in the comparison between the predictions and the measured stress-strain curves, which could facilitate the relevant fine analysis and resilient design in the future.

Inhomogeneity and anisotropy of Al-Zn-Mg-Cu alloy manufactured by wire arc additive manufacturing: microstructure, mechanical properties, stress corrosion cracking susceptibility

ABSTRACT In this study, Al-Zn-Mg-Cu alloy components were prepared using wire arc additive manufacturing (WAAM). Through multi-scale characterisation technology, performance testing and slow strain rate tensile (SSRT) testing, the microstructure, mechanical properties and stress corrosion cracking (SCC) susceptibility of WAAM Al-Zn-Mg-Cu components were studied, revealing the generation mechanism of inhomogeneity and anisotropy. The results show that with the increase of WAAM thermal cycles, the matrix precipitates (MPs), grain boundary precipitates (GBPs) and precipitation-free zones (PFZ) evolve in different paths and increase to varying degrees, resulting in performance decrease and increase in stress corrosion susceptibility, so the inhomogeneity is mainly attributed to differences in precipitated phases. The Inter-layer inclined to the scanning direction and the Inner-layer inclined to the building direction led to anisotropy in tensile strength and SCC behaviour, so the anisotropy is mainly attributed to the grain orientation and fracture mode.

Design, Manufacturing, and Analysis of Periodic Three-Dimensional Cellular Materials for Energy Absorption Applications: A Critical Review.

Cellular materials offer industries the ability to close gaps in the material selection design space with properties not otherwise achievable by bulk, monolithic counterparts. Their superior specific strength, stiffness, and energy absorption, as well as their multi-functionality, makes them desirable for a wide range of applications. The objective of this paper is to compile and present a review of the open literature focusing on the energy absorption of periodic three-dimensional cellular materials. The review begins with the methodical cataloging of qualitative and quantitative elements from 100 papers in the available literature and then provides readers with a thorough overview of the state of this research field, discussing areas such as parent material(s), manufacturing methods, cell topologies, cross-section shapes for truss topologies, analysis methods, loading types, and test strain rates. Based on these collected data, areas of great and limited research are identified and future avenues of interest are suggested for the continued maturation and growth of this field, such as the development of a consistent naming and classification system for topologies; the creation of test standards considering additive manufacturing processes; further investigation of non-uniform and non-cylindrical struts on the performance of truss lattices; and further investigation into the performance of lattice materials under the impact of non-flat surfaces and projectiles. Finally, the numerical energy absorption (by mass and by volume) data of 76 papers are presented across multiple property selection charts, highlighting various materials, manufacturing methods, and topology groups. While there are noticeable differences at certain densities, the graphs show that the categorical differences within those groups have large overlap in terms of energy absorption performance and can be referenced to identify areas for further investigation and to help in the preliminary design process by researchers and industry professionals alike.

Evaluation of the Genotoxicity of Almond Hull: Implications for Its Use as a Novel Food Ingredient.

Almond hull, a substantial byproduct comprising more than half of almond fresh weight, has recently gained attention due to its functionality and sustainability benefits. Despite heightened interest, information regarding its toxicity remains limited. In order to assess its genotoxic potential, we conducted Good Laboratory Practice-compliant in vitro and in vivo studies following Organization for Economic Co-operation and Development (OECD) guidelines. No evidence of toxicity or mutagenicity was observed in a bacterial reverse mutation assay using five tester strains, evaluating almond hull at concentrations up to 5 mg/plate, with or without metabolic activation. Almond hull did not induce chromosome structural damage in a chromosome aberration assay using Chinese hamster ovary cells, nor did it cause any spermatogonial chromosomal aberration in tested male BALB/c mice. To evaluate its ability to induce DNA damage in rodents, a combined micronucleus assay was conducted in KM mice of both sexes. Almond hull was administered at doses of 1250, 2500, and 5000 mg/kg/day via gavage once daily for 2 days. No adverse effects of almond hull were observed in the micronucleus assay. Our results indicate no evidence of the genotoxic potential of almond hull administered up to the maximum concentrations of 5 g/kg, as recommended by OECD guidelines.

Phenotypic microarray characterization of hemolytic and non-hemolytic strains of Listeria monocytogenes

Limited information is available on the phenotypic characteristics of Listeriamonocytogenes that may affect its virulence of L.monocytogenes. The study focused on comparing the differences between two strains of L. monocytogenes, one hemolytic (LLO+) and one non-hemolytic (tLLO). Using Phenotype Microarray (PM) technology, carbon, nitrogen, and phosphorus-sulfur source utilization by the strains was performed and the KEGG pathway involvement in substrate utilization was analyzed. Of the 285 substrates screened, the results suggested that d-gluconic acid and l-serine may play a role in L. monocytogenes hemolytic activity towards LLO production by generating pyruvate as an intermediate and amino acid biosynthesis, which may play an important role in virulence protein translation. d-gluconic acid and l-serine showed no effect on the tLLO strain in PM analysis and validation tests. Notably, the scope of this study was limited to these two strains of L. monocytogenes. While these findings provide valuable insights into the metabolic differences between hemolytic and non-hemolytic strains, further research is necessary to expand this understanding to a broader range of strains and explore additional factors that may influence LLO functionality.