Resistive Gas Sensors Based on 2D TMDs and MXenes.

ConspectusGas sensors are used in various applications to sense toxic gases, mainly for enhanced safety. Resistive sensors are particularly popular owing to their ability to detect trace amounts of gases, high stability, fast response times, and affordability. Semiconducting metal oxides are commonly employed in the fabrication of resistive gas sensors. However, these sensors often require high working temperatures, bringing about increased energy consumption and reduced selectivity. Furthermore, they do not have enough flexibility, and their performance is significantly decreased under bending, stretching, or twisting. To address these challenges, alternative materials capable of operating at lower temperatures with high flexibility are needed. Two-dimensional (2D) materials such as MXenes and transition-metal dichalcogenides (TMDs) offer high surface area and conductivity owing to their unique 2D structure, making them promising candidates for realization of resistive gas sensors. Nevertheless, their sensing performance in pristine form is typically weak and unacceptable, particularly in terms of response, selectivity, and recovery time (trec). To overcome these drawbacks, several strategies can be employed to enhance their sensing properties. Noble-metal decoration such as (Au, Pt, Pd, Rh, Ag) is a highly promising method, in which the catalytic effects of noble metals as well as formation of potential barriers with MXenes or TMDs eventually contribute to boosted response. Additionally, bimetallic noble metals such as Pt-Pd and Au/Pd with their synergistic properties can further improve sensor performance. Ion implantation is another feasible approach, involving doping of sensing materials with the desired concentration of dopants through control over the energy and dosage of the irradiation ions as well as creation of structural defects such as oxygen vacancies through high-energy ion-beam irradiation, contributing to enhanced sensing capabilities. The formation of core-shell structures is also effective, creating numerous interfaces between core and shell materials that optimize the sensing characteristics. However, the shell thickness needs to be carefully optimized to achieve the best sensing output. To reduce energy consumption, sensors can operate in a self-heating condition where an external voltage is applied to the electrodes, significantly lowering the power requirements. This enables sensors to function in energy-constrained environments, such as remote or low-energy areas. An important advantage of 2D MXenes and TMDs is their high mechanical flexibility. Unlike semiconducting metal oxides that lack mechanical flexibility, MXenes and TMDs can maintain their sensing performance even when integrated onto flexible substrates and subjected to bending, tilting, or stretching. This flexibility makes them ideal for fabricating flexible and portable gas sensors that rigid sensors cannot achieve.

Exogenously applied silver nanoparticles (AgNPs) differentially affect bacterial blight disease control in twenty-seven wheat cultivars.

The bacterial blight of wheat is an important global disease causing a significant decline in crop yield. Nanotechnology offers a potential solution for managing plant diseases. Therefore, this research aimed to investigate the effectiveness of silver nanoparticles (AgNPs) in controlling bacterial blight in 27 locally grown wheat cultivars. The study examined the impact of AgNPs at three distinct time points: 1, 3, and 5 days after the onset of the disease. Biochemical assay revealed that one day after applying the disease stress, the Inia cultivar had the highest amount of soluble protein (55.60 µg.g-1FW) content in the treatment without AgNPs. The Azadi cultivar, without AgNPs treatment, had the lowest amount of soluble protein content (15.71 µg.g-1FW). The Tabasi cultivar had the highest activity of the superoxide dismutase (SOD) (61.62 mM.g-1FW) with the combination treatment of AgNPs. On the other hand, the Karchia cultivar had the lowest SOD activity (0.6 mM.g-1FW) in the treatment of disease without AgNPs. Furthermore, three days after the application of stress, the Mahdavi cultivar had the highest amount of soluble protein content (54.16 µg.g-1FW) in the treatment of disease without AgNPs. The Niknejad cultivar had the highest activity of the SOD (74.15 mM.g-1FW) with the combined treatment of the disease without AgNPs. The Kavir cultivar had the lowest SOD activity (1.95 mM.g-1FW) and the lowest peroxidase (POX) activity (0.241 mM g-1FW min-1) in the treatment of the disease with AgNPs. Five days after exposure to stress, the Mahooti cultivar had the highest SOD activity (88.12 mM.g-1FW) with the combined treatment of the disease with AgNPs, and the Karchia cultivar had the lowest SOD activity (2.39 mM.g-1FW) in the treatment of the disease with AgNPs. Further, the results indicated that exposure to AgNPs could improve the antioxidant properties of wheat seeds in blight-infected and disease-free conditions in some cultivars.

Resistive gas sensors for the detection of NH3gas based on 2D WS2, WSe2, MoS2, and MoSe2: a review.

Transition metal dichalcogenides (TMDs) with a two-dimensional (2D) structure and semiconducting features are highly favorable for the production of NH3gas sensors. Among the TMD family, WS2, WSe2, MoS2, and MoSe2exhibit high conductivity and a high surface area, along with high availability, reasons for which they are favored in gas-sensing studies. In this review, we have discussed the structure, synthesis, and NH3sensing characteristics of pristine, decorated, doped, and composite-based WS2, WSe2, MoS2, and MoSe2gas sensors. Both experimental and theoretical studies are considered. Furthermore, both room temperature and higher temperature gas sensors are discussed. We also emphasized the gas-sensing mechanism. Thus, this review provides a reference for researchers working in the field of 2D TMD gas sensors.

Selecting the Best Gastric Anatomical Place for Biopsy to Detect Helicobacter Pylori in Iranian Morbid Obese Patients.

Background: Obesity and Helicobacter pylori (H. pylori) infection are public health problems in the world and Iran. This study aimed to indicate the anatomical place with the most accurate results for H. pylori. According to gastric mapping, this study will be able to evaluate the prevalence of H. pylori based on the pathology of gastric mapping and the accuracy of the antral rapid urease test (RUT) based on endoscopic findings. Methods: In this cross-sectional study, upper digestive endoscopy and gastric pathology were studied in 196 obese patients candidates for bariatric surgery. Statistical analyses were performed using a t-test and Chi-square/fisher's exact test to compare the groups. Sensitivity, specificity, accuracy, positive predictive value (PPV), negative predictive value (NPV), positive likelihood ratio (PLR), negative likelihood ratio (NLR), and odds ratio (OR) were used to compare RUT and pathological H. pylori test of each of the six areas of the stomach. We set a positive test of the pathology of 6 regions of the stomach as our gold standard (in this study). Results: The most common area of the stomach for pathological findings of H. pylori were incisura (116, 59.2%), greater curvature of the antrum (115, 58.3%), lesser curvature of the antrum (113, 57.7%), lesser curvature of the corpus (112, 57.1%), greater curvature of the corpus (111, 56.6%) and cardia (103, 52.6%). The prevalence of H. pylori was 58.2% (114 cases) and 61.2% (120 cases) with RUT and gastric pathology, respectively. Mild, moderate, and severe infection of H. pylori in cardia (58, 29.6%), greater and lesser curvature of the antrum (61, 31.1%), and greater curvature of the antrum (37, 18.9%) had the highest percentages of incidence comparing to other sites of the stomach, respectively. The most sensitive area for pathologic biopsy was incisura (96.6%, 95% confidence interval: 91.7, 98.7). Conclusion: According to the highest sensitivity, PLR, NPV, and pathological findings of H. pylori in accordance with the lowest NLR in the incisura compared with other parts of the stomach, it is highly recommended to take the biopsy from the incisura instead of other anatomical places of stomach for detecting H. pylori specifically if our strategy is taking only one biopsy.

Gas sensing properties of hematite nanoparticles synthesized via different techniques.

The synthesis techniques used for metal oxide semiconductors strongly influence their chemical, physical and gas sensing characteristics. In this context, hematite (α-Fe2O3) nanoparticles (NPs) were synthesized using two different techniques, namely, sol-gel (named HSG) and Pechini sol-gel (named HPSG). The average crystallite size and surface area were 15 nm and 76 m2 g-1 and 20 nm and 57 m2 g-1 for HPSG and HSG, respectively. Morphological studies showed that the HSG material was composed of ellipsoid-shaped particles, while the HPSG material had peanut-shaped particles with open pores and channels. The comparison between the sensing performances of HPSG and HSG toward ethanol indicated HPSG to be a better sensing material for ethanol detection. The HPSG sensor exhibited a response of 12 toward 500 ppm ethanol at 250 °C, a fast response time of 5 s and excellent selectivity. The enhanced characteristics were mainly related to the peculiar morphology with a porous nature, which led to more gas adsorption and diffusion. In addition to shape influence, the size of NPs also has an effect on the gas sensing performance. In fact, a decrease in the crystallite size led to an increase in the surface area of the material where the gas molecule-sensing layer interaction took place. The increase in the surface area created more interaction sites, and thus the sensitivity was improved. From these results, the HPSG sensor can be regarded as a promising candidate for ethanol detection.

2D nanomaterials for realization of flexible and wearable gas sensors: A review.

Gas sensors are extensively employed for monitoring and detection of hazardous gases and vapors. Many of them are produced on rigid substrates, but flexible and wearable gas sensors are needed for intriguing usage including the internet of things (IoT) and medical devices. The materials with the greatest potential for the fabrication of flexible and wearable gas sensing devices are two-dimensional (2D) semiconducting nanomaterials, which consist of graphene and its substitutes, transition metal dichalcogenides, and MXenes. These types of materials have good mechanical flexibility, high charge carrier mobility, a large area of surface, an abundance of defects and dangling bonds, and, in certain instances adequate transparency and ease of synthesis. In this review, we have addressed the different 2D nonmaterial properties for gas sensing in the context of fabrication of flexible/wearable gas sensors. We have discussed the sensing performance of flexible/wearable gas sensors in various forms such as pristine, composite and noble metal decorated. We believe that content of this review paper is greatly useful for the researchers working in the research area of fabrication of flexible/wearable gas sensors.

Targeted delivery of interleukin-12 plasmid into HepG2 cells through folic acid conjugated graphene oxide nanocarrier.

Successful gene therapy relies on carriers to transfer genetic materials with high efficiency and low toxicity in a targeted manner. To enhance targeted cell binding and uptake, we developed and synthesized a new gene delivery vector based on graphene oxide (GO) modified by branched polyethyleneimine (BPEI) and folic acid (FA). The GO-PEI-FA nanocarriers exhibit lower toxicity compared to unmodified PEI, as well as having the potential to efficiently condense and protect pDNA. Interestingly, increasing the polymer content in the polyplex formulation improved plasmid transfer ability. Substituting graphene oxide for PEI at an N/P ratio of 10 in the HepG2 and THP1 cell lines improved hIL-12 expression by up to approximately eightfold compared to simple PEI, which is twice as high as GO-PEI-FA in Hek293 at the same N/P ratio. Therefore, the GO-PEI-FA described in this study may serve as a targeting nanocarrier for the delivery of the hIL-12 plasmid into cells overexpressing folic acid receptors, such as those found in hepatocellular carcinoma.

Promising influences of hesperidin and hesperetin against diabetes and its complications: a systematic review of molecular, cellular, and metabolic effects.

Hesperidin and hesperetin, two flavonoids with potential therapeutic value, have been extensively studied in the context of diabetes management. The main objective of this research is to ascertain their potential as therapeutic options for managing diabetes and its complications. The present study utilized a systematic review methodology and comprehensively explored relevant literature from databases, including PubMed, Scopus, and Web of Science, from inception until July 2023. The review summarized the outcomes related to the molecular, cellular, and metabolic effects of hesperidin and hesperetin in diabetes and its complications. Hesperetin exhibits a potential treatment for preventing diabetes and its associated complications through modulation of inflammatory cytokine release and expression via the pathway of signaling through Toll-like receptor/Myeloid differentiation factor 88/Nuclear factor-kappa B. Hesperidin shows promise as a biomolecule for treating diabetic neuropathy, primarily through activation of nuclear factor erythroid 2-related factor 2 (Nrf-2), as an antioxidant-response element signaling, leading to neuroprotective effects. Both compounds demonstrated the ability to normalize blood glucose levels and reduce serum and liver lipid levels, making them potential candidates for managing hypoglycemia and hypolipidemia in diabetes. Hesperidin also showed potential benefits against diabetic nephropathy by suppressing transforming growth factor-ß1-integrin-linked kinase-Akt signaling and enhancing renal function. Furthermore, hesperidin's antioxidant, anti-inflammatory, and anti-depressant effects in diabetic conditions expanded its potential therapeutic applications. This systematic review provides substantial evidence supporting the consideration of hesperidin and hesperetin for diabetes and its complications. It offers exciting possibilities for developing novel, cost-effective treatment options to enhance diabetes management and patient outcomes.