Search Results (124)

Background: Helicobacter pylori is associated with a wide range of gastroduodenal diseases, including chronic gastritis, peptic ulcer disease, and gastric cancer. Eradication efforts are challenged by increasing antimicrobial resistance rates, particularly in Southeast Asia. We sequenced the whole genomes of clinical H. pylori isolates from Southern Thailand to elucidate their resistance profiles, virulence determinants, and evolutionary relationships. Methods: Three clinical H. pylori isolates (004, 117, and 189) were subjected to whole-genome sequencing, phenotypic antimicrobial susceptibility testing, and comparative genomic analyses. Results: All strains exhibited high-level resistance to metronidazole. Additionally, H. pylori 117 was resistant to both amoxicillin and levofloxacin, classifying it as multidrug-resistant. Genomic analysis revealed mutations in rdxA, frxA, and rpoB, as well as in penicillin-binding protein genes (pbp2 and pbp3), supporting the phenotypic findings. While all isolates harboured clarithromycin resistance mutations (A2142G and A2143G in the 23S rRNA gene), they were phenotypically susceptible, highlighting a potential discordance that requires further investigation. Virulence gene profiling identified 115–118 conserved genes per strain, including cagA, vacA, oipA, babA, and flagellar, urease, and lipopolysaccharide biosynthesis genes. Phylogenetic analysis using core-genome single-nucleotide polymorphisms demonstrated that these strains formed a distinct Southern Thai monophyletic clade, suggesting localised clonal expansion driven by regional selective pressures. Conclusions: Region-specific surveillance strategies and treatment guidelines are urgently needed in Thailand. The combination of high-risk virulence genes and rising antimicrobial resistance in H. pylori strains necessitates tailored therapeutic approaches, the integration of genomic surveillance into clinical diagnostics, and expanded studies linking genotype to clinical outcomes in diverse populations. Full article

Background/Objectives: Helicobacter pylori (H. pylori) is a common gastric pathogen linked to gastritis, gastroduodenal ulcers, and gastric cancer. Rising antimicrobial resistance (AMR) poses challenges for effective treatment and has prompted the WHO to classify H. pylori as a high-priority pathogen. This study aimed to detect the prevalence of AMR genes in H. pylori-positive gastric samples from patients in Algarve, Portugal, where regional data is scarce. Methods: Eighteen H. pylori-positive gastric biopsy samples from patients undergoing upper gastrointestinal endoscopy were analyzed. PCR and sequencing were used to identify genes associated with resistance to amoxicillin (Pbp1A), metronidazole (rdxA, frxA), tetracycline (16S rRNA mutation) and clarithromycin (23S rRNA). Sequence identity and homologies were verified using tBLASTx and the Comprehensive Antibiotic Resistance Database (CARD). Results: Out of the 18 H. pylori-positive samples, 16 (88.9%) contained at least one AMR gene. The most frequent genes were rdxA (83.3%) and frxA (66.7%) for metronidazole resistance, and the 16S rRNA mutation (66.7%) for tetracycline. Resistance to amoxicillin and clarithromycin was detected in 27.8% and 16.7% of cases, respectively. Most samples (72.2%) had multiple resistance genes. A significantly strong association was found between female sex and the presence of the rdxA gene (p = 0.043). Conclusions: The study reveals a high prevalence of H. pylori resistance genes in Algarve, particularly against metronidazole and tetracycline. These findings highlight the need for local surveillance and tailored treatment strategies. Further research with larger populations is warranted to assess regional resistance patterns and improve eradication efforts. Full article

Microplastics (MPs) and nanoplastics (NPs) can affect microbial abundance and activity, likely by damaging cell membrane components. While their effects on anaerobic digestion are known, less is understood about their impact on microbes involved in contaminant bioremediation. Chlorinated volatile organic contaminants (CVOCs) such as tetrachloroethene (PCE) and explosives like hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) are common in the environment, and their bioremediation is a promising cleanup strategy. This study examined how polystyrene (PS) and polyamide 6 (PA6) MPs and NPs influence CVOC and RDX biodegradation. PS particles did not inhibit the CVOC-degrading community SDC-9, but PA6 MPs impaired the reductive dechlorination of trichloroethene (TCE) to cis-1,2-dichloroethene (cis-DCE), causing a “cis-DCE stall” with no further conversion to vinyl chloride (VC) or ethene. Only 45% of TCE was dechlorinated to cis-DCE, and Dehalococcoides mccartyi abundance dropped 1000-fold in 35 days with PA6 MPs. In contrast, neither PA6 nor PS MPs and NPs affected RDX biotransformation. These results highlight the significant impact of PA6 MPs on CVOC biodegradation and the need to consider plastic pollution in environmental management. Full article

Helicobacter pylori antibiotic resistance data in Oman are limited yet crucial for effective treatment selection. The genetic diversity within H. pylori influences its pathogenicity and clinical outcomes. This study evaluates resistance patterns and genetic determinants to guide treatment strategies. This study assessed antibiotic susceptibility in 15 H. pylori isolates (from 169 clinical samples) from naïve and treatment-failed patients. Resistance to clarithromycin (CLA), amoxicillin (AMX), metronidazole (MTZ), tetracycline, rifampicin (RIF), and levofloxacin (LEV) was tested alongside genetic analysis of virulence and resistance-associated mutations by whole-genome sequencing (WGS). Among the 15 resistant isolates, 20% were resistant to one antibiotic, 33.3% to two, 20% to three, and 26.6% to four antibiotics. MTZ resistance was universal among single-drug resistant isolates (100%). AMX-MTZ dual resistance was present in 60%, while triple resistance (CLA-AMX-MTZ) was present in 66.7%. Quadruple resistance (CLA-AMX-MTZ-RIF) was present in 75%. WGS revealed 23S rRNA mutations in 33.3% of CLA-resistant strains and pbp-1 mutations in 66.6% of AMX-resistant strains. MTZ resistance was linked to rdxA/frxA mutations, while RIF and LEV resistance correlated with rpoB (65.7%) and gyrA (20%) mutations, respectively. The genotype–phenotype agreement was insignificant (p = 1). High mutation heterogeneity, virulence factors, and environmental influences contribute to resistance. Further studies on host–pathogen interactions are needed to understand resistance mechanisms. Full article

Modern energetic materials (EMs) have many different civil applications. One of their most promising applications in civil engineering is explosive hardening, which facilitates the fast and cost-effective improvement of mechanical properties in the treated material. In this work, we present the results of our investigation on the explosive hardening of S235JR Steel with PBX formulations containing silicone binders and 1,3,5-trinitro-1,3,5-triazinane (RDX). In terms of safety, the impact (5–15 J) and friction (240–360 N) sensitivity of the tested plastic-bonded explosives (PBXs) was verified, simultaneously with DSC tests, energy of activation calculations, and critical diameter measurement. The developed material, prepared with techniques similar to the anticipated working conditions, is characterized by a high detonation velocity (up to 7300 m/s), low sensitivity for mechanical factors (10 J, 288 N), and a small critical diameter (3.3 mm). The developed PBX based on a silicone binder demonstrated grain fragmentation, recrystallization, and an increase in the surface hardness of S235JR steel, which was confirmed with SEM, EBSD, microstructure analysis, and microhardness studies. Full article

Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) is a globally recognized energetic material that widely used in industrial, mining, and military fields. Like hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and other nitramine compounds, HMX has also been reported to exhibit neurotoxicity. However, the molecular mechanisms underlying the toxic effects of HMX remain poorly understood. Therefore, this study aims to investigate the neurotoxicity induced by HMX by adopting PC12 cells. The results show that HMX treatment decreased cell viability and upregulated the intracellular free calcium ions (Ca²⁺) in PC12 cells. Furthermore, HMX caused aggravated oxidative stress in PC12 cells, as evidenced by the upregulations of reactive oxygen species (ROS) and malondialdehyde (MDA). Intracellular biochemical assays demonstrated that HMX induced loss of mitochondrial membrane potential in PC12 cells. Notably, altered expression of brain-derived neurotrophic factor (BDNF) and ionotropic glutamate receptors (iGluRs), as well as an abnormal transcription profile, were also observed in PC12 cells treated by HMX. These findings suggest that HMX exerts toxic effects on PC12 cells, involved in oxidative stress, and disturbances in Ca²⁺ and BDNF, accompanied by aberrant iGluRs. Overall, the present study helps us better understand the health hazards associated with HMX and provides valuable insights for developing the health protection standards related to HMX exposure. Full article

This study investigates tandem queues with two service nodes. The consumer needs to obtain services at the following two nodes in this system: the IBM online sphere for artificial intelligence (AI) and the complex RDX mechanism. Before the second essential service (SES), by utilizing AI to validate the data in IBM WebSphere and insight, the first essential service (FES) begins with the RDX mechanism. If there are fewer customers than “a” after a service at node 1 is finished, the server departs for a subsequent assignment. As soon as the vacation value reached the threshold, the service began. After the service concludes at node 1, it moves on to node 2. In this study, the supplemental variable technique is used to determine the probability-generating function (PGF) at any given time. A numerical solution also yields certain features of the queueing system. Full article

The influence of the roughness of porcelain plates on the results of the friction sensitivity test of explosives was investigated. For this purpose, the roughness of selected batches of plates from several manufacturers (Julius Peters, OZM Research s.r.o., Deltima Precision s.r.o.) was determined. Subsequently, according to the standards EN 13631-3:2005 and STANAG 4487 JAIS (edition 2), friction sensitivity tests of PETN (Pentaerythritol Tetranitrate, penthrite) and RDX (Royal Demolition Explosive, hexogen) were carried out. No statistically significant correlation was established under the experimental conditions—although sanded plates had the lowest roughness (mean value 5.07 μm) and simultaneously gave the lowest sensitivity results (168 N for RDX and 80 N for PETN according to the EN 13631-3 while 216 N for RDX and 121 N for PETN according to the STANAG 4487), Julius Peters plates with a similar level of roughness (mean value 6.07 μm) did not reflect the pattern and results of the sensitivity tests that were surprisingly high (120 N for RDX and 64 N for PETN according to the EN 13631-3 while 182 N for RDX and 67 N for PETN according to the STANAG 4487). Due to these results, the human factor is indicated as a key factor in the obtained discrepancies; however, further research in this matter may be needed. Full article

Structural research teams face significant challenges when conducting studies with explosives, including the costs and inherent risks associated with field detonation tests. This study presents a replicable method for loading spherical and bare TNT-based cast explosive charges, offering reduced costs and minimal risks. Over eighty TNT and Composition B charges (comprising 60% RDX, 39% TNT, and 1% wax) were prepared using spherical molds made of thin aluminum, which are low-cost, off-the-shelf solutions. The charges were bare, meaning they lacked any casing, as the molds were designed to be easily removed after casting. The resulting charges were safer due to their smaller dimensions and the absence of hazardous metallic debris. Composition B charges demonstrated promising results, with their performance characterized through blast and thermochemical experiments. Comprehensive data are provided for Composition B charges, including TNT equivalence, pressures, velocity of detonation, DSC/TGA curves at four different heating rates, activation energy, peak decomposition temperatures, X-ray analysis, and statistics on masses and densities. A comparison between detonation and deflagration processes, captured in high-speed footage, is also presented. This explosive characterization is crucial for structural teams to precisely understand the blast loads produced, ensuring a clear and accurate knowledge of the forces acting on structures. Full article

Antibiotic resistance in Helicobacter pylori is increasing rapidly and emerging as a major factor in treatment failure. We aimed to identify genetic mutations associated with resistance to clarithromycin (23S rRNA peptidyl transferase), fluoroquinolones (gyrA), and metronidazole (rdxA), and to explore their mechanisms of action through molecular modeling. H. pylori detection and the molecular characterization of genes were conducted directly on gastric biopsies by real-time PCR followed by nucleotide sequencing. A 3D model was used to evaluate molecular interactions between the antibiotics and respective target proteins. H. pylori was identified in 66.7% of 33 patients. An analysis of 23SrRNA revealed novel mutations that, by in silico analysis, do not appear to contribute to clarithromycin resistance. In gyrA, mutations in amino acid residues 87 and 91 had an incidence of 27%, and the in silico analysis revealed that these positions are relevant in the binding and resistance to fluoroquinolones. It is also reported for other mutations, some of which are never described. All rdxA mutations were missense, with R16H, M56V, H97T, G98S, A118T, V123T, and R131K predicted by in silico analysis to impact metronidazole resistance. Monitoring H. pylori gene mutations is crucial for tailoring effective antibiotic therapies. Our study advances personalized medicine by introducing novel methods to detect resistance-related mutations and uncovering the molecular mechanisms driving this resistance. Full article

Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), a typical representative of energetic materials, is widely applied in military and industrial fields with its high energy density and excellent detonation performances. However, when used as a raw material for propellants and rocket propellants, RDX poses certain safety concerns due to its high sensitivity to external stimuli such as electrostatic discharge, impact, and friction, which limits its further application. Herein, to reduce the RDX electrostatic spark and mechanical sensitivities and improve safety performances, a conductive polymer of poly(3,4-ethylene-dioxythiophene)–poly(styrenesulfonate) (PEDOT:PSS) was introduced into the energetic material system based on a simple suction filtration method. RDX-based energetic composites with varying PEDOT:PSS mass fractions were prepared by both micron-sized RDX and nanosized RDX. The RDX-based energetic composites were characterized, and their response characteristics and performances were tested and compared. The results demonstrated that the conductive interfaces constructed by PEDOT:PSS on the RDX surface significantly reduced the electrostatic spark and mechanical sensitivity. The electrostatic spark sensitivity of μ-RDX-based energetic composites decreased by 40%, while the impact sensitivity and friction sensitivity decreased by 76.47% and 50%, respectively. Compared to micron-sized RDX-based energetic composites, the nano-sized RDX-based energetic composites desensitization effect on electrostatic spark sensitivity was more pronounced. For n-RDX-based energetic composites, the electrostatic spark sensitivity decreased by 66.4%. Furthermore, the assembly and desensitization mechanism of the RDX-based energetic composites were thoroughly investigated. This study not only provides a simple and reliable assembly method for the safe application of RDX but also offers corresponding data and experimental support for future research, which is of significant importance for the application of energetic materials. Full article

Helicobacter pylori infects at least half the population worldwide, and its highly diverse genomic content correlates with its geographic distribution because of its prolonged relationship with humans. The extremely low infection prevalence alongside low inflammation severity observed in some countries might be caused by strains with low virulence potential. Therefore, this study aimed to investigate whole-genome analysis datasets of Sri Lankan H. pylori strains. H. pylori strains were isolated from biopsy specimens and underwent whole-genome sequencing to investigate their antibiotic resistance and virulence potential. The prevalence of H. pylori infection in Sri Lanka is extremely low (1.7% in a previous study), and only six H. pylori strains were successfully isolated from bacterial culture. Antibiotic resistance analysis showed a high prevalence of metronidazole resistance (83.3%, five out of six strains), and investigation of the related genes showed truncation of the rdxA and frxA genes and single-nucleotide polymorphisms in the rdxA, frxA, ribF, omp11, and fur genes. Most virulence genes of the 144 assessed were present, except for the cag pathogenicity island (cagPAI) (absent in four out of six strains), babA/B/C, and tlpB genes. An incomplete type 4 secretion system (tfs) was found in three strains. A pan-genome analysis with non-Sri Lankan H. pylori strains showed that the htpX gene was found only in Sri Lankan strains (p-corrected = 0.0008). A phylogenetic analysis showed that the Sri Lankan strains clustered with strains from hpAsia2 and hpEurope. This comparative genomic study shows that H. pylori strains with low virulence potential are present in countries with a low prevalence of infection and disease severity, indicating a strain-type geographical pattern. The tailored guidelines for screening and treatment strategy for each region are necessary to obtain effective and efficient eradication. Full article

Remnant explosive devices are a deadly nuisance to both military personnel and civilians. Traditional mine detection and clearing is dangerous, time-consuming, and expensive. And routine production and testing of explosives can create groundwater contamination issues. Remote detection methods could be rapidly deployed in vegetated areas containing explosives as they are known to cause stress in vegetation that is detectable with hyperspectral sensors. Hyperspectral imagery was employed in a mesocosm study comparing stress from a natural source (drought) to that of plants exposed to two different concentrations of Royal Demolition Explosive (RDX; 250 mg kg⁻¹, 500 mg kg⁻¹). Classification was accomplished with the machine learning algorithms Support Vector Machine (SVM), Random Forest (RF), and Least Discriminant Analysis (LDA). Leaf-level plant data assisted in validating plant stress induced by the presence of explosives and was detectable. Vegetation indices (VIs) have historically been used for dimension reduction due to computational limitations; however, we measured improvements in model precision, recall, and accuracy when using the complete range of available wavelengths. In fact, almost all models applied to spectral data outperformed their index counterparts. While challenges exist in scaling research efforts from the greenhouse to the field (i.e., weather, solar lighting conditions, altitude when imaging from a UAV, runoff containment, etc.), this experiment is promising for subsequent research efforts at greater scale and complexity aimed at detecting emerging contaminants. Full article

Background: The detection of explosives in crime scene investigations is critical for forensic science. This study explores the application of laser desorption (LD) ion mobility spectrometry (IMS) as a novel method for this purpose utilising a new IMS prototype developed by MaSaTECH. Methods: The LD sampling technique employs a laser diode module to vaporise explosive traces on surfaces, allowing immediate analysis by IMS without sample preparation. Chemometric approaches, including multivariate data analysis, were utilised for data processing and interpretation, including pre-processing of raw IMS plasmagrams and various pattern recognition techniques, such as linear discriminant analysis (LDA) and support vector machines (SVMs). Results: The IMS prototype was validated through experiments with pure explosives (TNT, RDX, PETN) and explosive products (SEMTEX 1A, C4) on different materials. The study found that the pre-processing method significantly impacts classification accuracy, with the PCA-LDA model demonstrating the best performance for real-world applications. Conclusions: The LD-IMS prototype, coupled with effective chemometric techniques, presents a promising methodology for the detection of explosives in forensic investigations, enhancing the reliability of field applications. Full article

The reactive molecular dynamics method was employed to examine the thermal decomposition process of aluminized hydride (AlH₃) containing explosive nanoparticles with a core–shell structure under high temperature. The core was composed of the explosives RDX, HMX, and CL-20, while the shell was composed of AlH₃. It was demonstrated that the CL-20@AlH₃ NPs decomposed at a faster rate than the other NPs, and elevated temperatures could accelerate the initial decomposition of the explosive molecules. The incorporation of aluminized hydride shells did not change the initial decomposition mechanism of the three explosives. The yields of the main products (NO, NO₂, N₂, H₂O, H₂, and CO₂) were investigated. There was a large number of solid aluminized clusters produced during the decomposition, mainly Al_mO_n and Al_mC_n clusters, together with Al_mN_n clusters dispersed in the Al_mO_n clusters. Full article