Oxide Gas Research Articles

Exogenous Sodium Nitroprusside Exhibits Multiple Positive Roles in Alleviating Cadmium Toxicity in Tobacco (Nicotiana tabacum L.).

As a donor of the gaseous signaling molecule nitric oxide (NO), sodium nitroprusside (SNP) has been shown to play a positive role in enhancing plant resistance to abiotic stress. However, its role in alleviating cadmium (Cd) toxicity in tobacco (Nicotiana tabacum L.) is not fully understood. This study found that Cd stress significantly inhibited tobacco growth. At the same time, 150 μM SNP was the most effective concentration in alleviating Cd toxicity in seedlings, restoring three stress tolerance indicators-MDA, H2O2, and proline-to control levels. Exogenous SNP mitigated Cd-induced oxidative stress by promoting the accumulation of non-enzymatic antioxidants (total phenolics and flavonoids) and activating key antioxidant enzymes (SOD, CAT, POD, APX, and GR) along with their gene expression. SNP also facilitated Cd accumulation in the root cell wall and prevented Cd translocation from roots to shoots. Additionally, SNP altered Cd's subcellular distribution, promoting its sequestration in vacuoles and cell walls, which may be related to the NO-mediated upregulation of the metallothionein gene NtMT2F and the phytochelatin gene NtPCS2. The addition of SNP significantly increased the proportion of Cd in less toxic chemical forms, with the residual Cd fraction in the Cd + SNP group reaching 7.30%, higher than the 4.86% in the Cd-only group. Furthermore, exogenous SNP counteracted Cd's inhibition of nitrate reductase (NR) activity, promoting endogenous NO production. This study systematically reveals the positive roles of exogenous SNP in mitigating Cd toxicity in tobacco, offering valuable insights for producing low-Cd tobacco.

Evaluation of the potential efficacy of the nitric oxide donor molsidomine for the treatment of schizophrenia.

Schizophrenia is a chronic devastating psychiatric disease characterized by a high recurrence rate. Pharmacological management of this disorder appears disappointing since it is associated with a lack of efficacy for negative symptoms and cognitive deficits, typical features of schizophrenia, and the presence of severe undesired side effects. Thus, novel molecules with high efficacy and low toxicity for the treatment of schizophrenia are urgently needed. The involvement of the gaseous molecule nitric oxide in the pathogenesis of schizophrenia is well documented since low concentrations of nitric oxide are associated with this psychiatric disease. Therefore, chemicals able to normalize nitric oxide levels, such as nitric oxide donors, might be useful for the management of this type of schizophrenia. Molsidomine is a nitric oxide donor and is under investigation as a novel antischizophrenia agent. The aim of this review is to critically evaluate the potential efficacy of this molecule for the treatment of schizophrenia.

Pillar[5]arene stabilized gold nanoparticles for the enhanced light-triggered nitric oxide release with antibacterial and antibiofilm activities

The reactivity of guests confined in well-defined host cavities act significantly different from that in bulk systems. In this work, pillar[5]arene not only works as a stabilizer for the fabrication of gold nanoparticles, but also act as an accelerator for the enhanced photo-triggered release of gaseous nitric oxide (NO) from encapsulated NO donor. The host–guest complex can dramatically improve the photoactivity of loaded guest molecule to generate antibacterial NO molecules through the confinement effect of pillar[5]arene cavity. The synergistic photo-triggered localized NO release and photo-thermal effect of host–guest complex demonstrated impressive antibacterial behaviors against Gram-negative bacterial strain Escherichia coli, Gram-positive bacterial strain Staphylococcus aureus and methicillin-resistant Staphylococcus aureus. Moreover, this biocompatible photo-responsive complex can also inhibit bacterial biofilm formation and disrupt the pre-existing biofilms.

VOC Detection with Zinc Oxide Gas Sensors: A Review of Fabrication, Performance, and Emerging Applications

Energy‐efficient, high‐specificity gas sensors provide practical suitability for stability and response factors. The recognition of ignitable gases (methane (CH <sub>4</sub>), propane (C <sub>3</sub>H <sub>8</sub>), and hydrogen (H <sub>2</sub>) and harmful gases (carbon oxide (CO) and hydrogen sulfide (H <sub>2</sub>S)) in an enclosed and out‐of‐door space are essential to safeguard the human lives and infrastructural spaces. One of the crucial conductive‐type metal oxide semiconductor (MOS) gas sensors yielding wide applications is zinc oxide (ZnO). This study highlights the various types of ZnO gas sensors, their fabrication techniques, and specific vital characterizations. The devices based on MOS are utilized to sense various target gases through redox reactions. The variation in oxide surface with target gas interactions is transduced to a change of sensor conductance. This review also provides insight into integrating ZnO gas sensors with technologies such as materials engineering, the Internet of things and big data. Moreover, this review addresses ZnO gas sensors' challenges and future directions.

Theoretical Study of the Magnetic Mechanism of a Pca21 C4N3 Monolayer and the Regulation of Its Magnetism by Gas Adsorption.

For metal-free low-dimensional ferromagnetic materials, a hopeful candidate for next-generation spintronic devices, investigating their magnetic mechanisms and exploring effective ways to regulate their magnetic properties are crucial for advancing their applications. Our work systematically investigated the origin of magnetism of a graphitic carbon nitride (Pca21 C4N3) monolayer based on the analysis on the partial electronic density of states. The magnetic moment of the Pca21 C4N3 originates from the spin-split of the 2pz orbit from special carbon (C) atoms and 2p orbit from N atoms around the Fermi energy, which was caused by the lone pair electrons in nitrogen (N) atoms. Notably, the magnetic moment of the Pca21 C4N3 monolayer could be effectively adjusted by adsorbing nitric oxide (NO) or oxygen (O2) gas molecules. The single magnetic electron from the adsorbed NO pairs with the unpaired electron in the N atom from the substrate, forming a Nsub-Nad bond, which reduces the system's magnetic moment from 4.00 μB to 2.99 μB. Moreover, the NO adsorption decreases the both spin-down and spin-up bandgaps, causing an increase in photoelectrical response efficiency. As for the case of O2 physisorption, it greatly enhances the magnetic moment of the Pca21 C4N3 monolayer from 4.00 μB to 6.00 μB through ferromagnetic coupling. This method of gas adsorption for tuning magnetic moments is reversible, simple, and cost-effective. Our findings reveal the magnetic mechanism of Pca21 C4N3 and its tunable magnetic performance realized by chemisorbing or physisorbing magnetic gas molecules, providing crucial theoretical foundations for the development and utilization of low-dimensional magnetic materials.

Enhancing nitrous oxide chemiresistive sensing performance by reducing ionic Oxygen species adsorption in Gold functionalized Tungsten Trioxide nanofibers

Low-cost nitrous oxide (N2O) gas sensor is in great need to provide real-time information to various stakeholders. Herein, various gold functionalized tungsten trioxide nanofibers (Au-WO3 NFs) with different composition and crystallinity were synthesized by controlling electrospinning solutions and post heat treatment. These sensing materials were systematically exposed to various N2O concentrations at different operating temperatures (i.e., 250 to 450 °C). Among different samples, 1 at % gold functionalized WO3 nanofibers (1 at % Au-WO3 NF) annealed at 600 °C for 24 h shows the highest sensitivity (S = Ra/Ro) of 38.5 toward 100 ppm at 250 °C with experimentally determined limit of detection (LOD) at 2.5 ppm. Although recovery and recovery time improved, the sensitivity reduced with an increase in operating temperatures. The detailed sensing mechanism studies indicated that the high N2O sensing was achieved when there were limited adsorbed ionized oxygen species (e.g., O-). Moreover, N2O adsorption and desorption activation energy were estimated to be 0.13 and 0.87 eV where desorption was more strongly temperature dependent than adsorption.

A sequential treatment strategy by copper ion-doped nanofiber dressing for highly efficient biofilm combating and rapid wound healing

Copper ions are considered as a promising alternative to combat infected wound and accelerate wound healing. However, exhibiting good antibiofilm activity meanwhile minimizing cell toxicity remains a great challenge. To address this issue, we provide a sequential treatment strategy to combat biofilm infected wound with low copper ion (Cu2+) release (as low as 1.2 μg·mL−1). Polydopamine (PDA) adherent copper ion complex is constructed on thermoplastic polyurethane (TPU) to develop the Cu2+@PTPU nanofibers. With the application of Cu2+@PTPU wound dressing, nitric oxide (NO) gas is released by catalyzing endogenous donor, thereby rapidly eliminating more than 90 % biofilm biomass. Subsequent moderate photothermal treatment (∼47℃) significantly enhanced bactericidal effect by deconstructing bacteria membrane. As a result, the biofilm infection was eradicated in only ∼ 6h, significantly more effective than existing methods (∼24 h). Additionally, Cu2+@PTPU dressing not only exhibits excellent cell compatibility, but also promotes wound healing. In vivo study demonstrates that it reduces the level of inflammatory responses by 104 % and increases angiogenesis capacity by 115 %, compared with untreated group, thereby narrowing the wound site area by 72 % at day 14 after treatment. Overall, the Cu2+@PTPU dressing and sequential treatment strategy provide quick, safe, yet efficacious biofilm combating outcomes and facilitates rapid wound healing.

Bee microbiomes in a changing climate: Investigating the effects of temperature on solitary bee life history and health.

Climate change is rapidly warming thermal environments, an important abiotic stimulus governing interactions between microbial symbionts and their hosts. Increasing evidence suggests that solitary bees rely on pollen provision microbes for successful development. However, the effects of heat stress on provision microbiota and the resulting consequences for larval health and development remain to be examined. We performed an in vitro study to investigate the effects of the thermal environment on provision microbiome composition and measured fitness outcomes for Osmia lignaria larvae. While pollen sterilisation removed bacteria from microbe-rich provisions, larval survivorship did not significantly differ between bees reared on microbe-rich (unmanipulated) diets and provisions treated with ethylene oxide (EO) gas. In contrast to previous research in solitary bees, larvae reared on EO-treated provisions weighed more and had higher total fat content, with temperature moderating the degree of difference. As anticipated, we observed a negative relationship between the duration of larval development and temperature. Our results indicated that an intact provision microbiota may not always improve bee fitness and that bee-microbe interactions during larval development may contribute to the size-shrinking effect observed for cavity-nesting bees under warming conditions.

A nanoporous nickel–iron alloy seamlessly anchored into hierarchical porous nickel for efficient and extremely stable water splitting

The development of a robust, low-cost electrode for electrochemical water splitting is a challenging, but essential task for realizing hydrogen production under industrial conditions. Here, we seamlessly anchor nanoporous nickel–iron into a hierarchical porous nickel foam (npNi–Fe/HPNF) by a designed gaseous oxidation–reduction engineering for a commercial nickel foam. The three-dimensional hierarchical porous structure considerably enhances the specific surface area of the electrode, yielding abundant electrocatalytic sites that promote the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Moreover, owing to its mechanically robust, seamlessly anchored architecture, and remarkable superhydrophilicity/superaerophobicity, the electrolyzer composed of self-standing npNi–Fe/HPNF and its electro-activation derivative displays a current density of 10 mA cm−2 at 1.54 V, ultralong durability of more than 2000 h at 500 mA cm−2 in a 1 M KOH electrolyte, and high performance of 2 V at 1 A cm−2 in a quasi-industrial environment (5 M KOH and 70 °C), outperforming most alkaline electrolyzers based on state-of-the-art electrodes. Exceptional electrochemical performance and the ability to be prepared at a large scale (2500 cm2) make npNi–Fe/HPNF a promising candidate for industrial water splitting applications.

Selecting an optimal sorghum cultivar can improve nitrogen availability and wheat yield in crop rotation.

Sorghum (Sorghum bicolor L. Moench) is a cereal crop known for its biological nitrification inhibition (BNI) capacity, a plant-mediated activity limiting nitrification pathway. The use of BNI-producing plants represents an environmentally friendly and cost-effective approach to reduce nitrogen (N) losses, such as nitrate (NO3 -) leaching and nitrous oxide (N2O) gas emissions. The present study aimed to test the effectiveness of different S. bicolor cultivars in rotation to retain ammonium (NH4 +) in soils and promote N availability for the subsequent wheat crop. A two-year field rotation was established with four sorghum cultivars followed by winter wheat (Triticum aestivum L.). Urea alone or combined with the urease inhibitor N-(n-butyl) thiophosphoric triamide was applied to promote a NH4 +-based fertilization regimes. AddingN-(n-butyl) thiophosphoric triamide maintained higher soil NH4 + content and reduced ammonia-oxidizing bacteria population during sorghum cultivation. However, the benefits of the inhibitor on sorghum growth were cultivar-dependent. Notably, the further reduction in ammonia-oxidizing bacteria abundance for sorghum Voyenn and the increased soil NH4 + content for Vilomene suggested a BNI potential for these cultivars. Importantly, the Vilomene precedent enhanced wheat yield for both fertilization regimes. Overall, the present study confirms that sorghum is a suitable catch crop and emphasizes the importance of selecting the proper sorghum cultivar to maximize the yield of the target wheat crop, at the same time as minimizing N losses. Furthermore, developing combined strategies with selected sorghum cultivars and the application of urease inhibitors enables to enhance sorghum productivity as forage, achieving added value to the rotation. © 2024 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

High Performance H2S Sensor Based on Ordered Fe2O3/Ti3C2 Nanostructure at Room Temperature.

The utilization of a heterogeneous nanojunction design has shown significant enhancements in the gas sensing capabilities of traditional metal oxide gas sensors. In this study, a novel room temperature H2S gas sensor employing Fe2O3 functionalized Ti3C2 MXene as the sensing material has been developed. This sensor exhibits a broad detection range (0.01-500 ppm), low detection limit (10 ppb), and rapid response/recovery times (10 s/15 s), making it ideal for ppb-level H2S detection. The exceptional gas sensitivity of Fe2O3/Ti3C2 composite to H2S can be attributed to several key factors. First, the unique layered frame structure of Fe2O3/Ti3C2 significantly amplifies the surface area of the hybrid material, enhancing the absorption and diffusion capabilities of H2S molecules. Second, the abundance of functional groups (-O, -OH, and -F) on the surface of Ti3C2 MXene nanosheets provides additional active sites for H2S adsorption, The density functional theory calculation confirms that the adsorption energy of the Fe2O3/Ti3C2 composite for H2S (-2.93 eV) is significantly lower than that of pure Fe2O3 (-2.37 eV) and Ti3C2 (-0.2 eV). Lastly, the remarkable metal conductivity of Ti3C2 MXene ensures efficient electron transfer, thereby enhancing overall sensing performance.

Resistance of Boron Nitride Nanotubes to Radiation-Induced Oxidation.

We present unprecedented results on the damage thresholds and pathways for boron nitride nanotubes (BNNT) under the influence of energetic electrons in an oxidative gas environment, using an environmental aberration-corrected electron microscope over a range of oxygen pressures. We observe a damage cascade process that resists damage until a higher electron dose, compared with carbon nanotubes, initiating at defect-free BNNT sidewalls and proceeding through the conversion from crystalline nanotubes to amorphous boron nitride (BN), resisting oxidation throughout. We compare with prior results on the oxidation of carbon nanotubes and present a model that attributes the onset of damage in both cases to a physisorbed oxygen layer that reduces the threshold for damage onset. Surprisingly, increased temperatures offer protection against damage, as do electron dose rates that significantly exceed the oxygen dose rates, and our model attributes both effects to a physisorbed oxygen population.

A Portable Electronic Nose Coupled with Deep Learning for Enhanced Detection and Differentiation of Local Thai Craft Spirits

In this study, our primary focus is the biomimetic design and rigorous evaluation of an economically viable and portable ‘e-nose’ system, tailored for the precise detection of a broad range of volatile organic compounds (VOCs) in local Thai craft spirits. This e-nose system is innovatively equipped with cost-efficient metal oxide gas sensors and a temperature/humidity sensor, ensuring comprehensive and accurate sensing. A custom-designed real-time data acquisition system is integrated, featuring gas flow control, humidity filters, dual sensing/reference chambers, an analog-to-digital converter, and seamless data integration with a laptop. Deep learning, utilizing a multilayer perceptron (MLP), is employed to achieve highly effective classification of local Thai craft spirits, demonstrated by a perfect classification accuracy of 100% in experimental studies. This work underscores the significant potential of biomimetic principles in advancing cost-effective, portable, and analytically precise e-nose systems, offering valuable insights into future applications of advanced gas sensor technology in food, biomedical, and environmental monitoring and safety.

Dissociation of the nuclear WWOX/TRAF2 switch renders UV/cold shock-mediated nuclear bubbling cell death at low temperatures

BackgroundNormal cells express functional tumor suppressor WW domain-containing oxidoreductase (WWOX), designated WWOXf. UV irradiation induces WWOXf cells to undergo bubbling cell death (BCD) — an event due to the accumulation of nuclear nitric oxide (NO) gas that forcefully pushes the nuclear and cell membranes to form one or two bubbles at room temperature (22 °C) and below. In contrast, when WWOX-deficient or -dysfunctional (WWOXd) cells are exposed to UV and/or cold shock, the cells undergo nuclear pop-out explosion death (POD). We aimed to determine the morphological and biochemical changes in WWOXf cells during BCD versus apoptosis.MethodsWWOXf and WWOXd cells were exposed to UV followed by measuring BCD or POD by time-lapse microscopy and/or time-lapse holographic microscopy at 4, 22, or 37 °C to visualize morphological changes. Live cell stains were used to measure the kinetics of nitric oxide (NO) production and Ca2+ influx. Extent of cell death was measured by uptake of propidium iodide and by internucleosomal DNA fragmentation using agarose gel electrophoresis.ResultsWWOXf cells were exposed to UV and then cold shock, or cold shock and then UV, and cultured at 4, 10, and 22 °C, respectively. Initially, UV induced calcium influx and NO production, which led to nuclear bubbling and final death. Cold shock pretreatment completely suppressed UV-mediated bubbling at 37 °C, so the UV/cold shock-treated cells underwent apoptosis. Without cold shock, UV only induced bubbling at all temperatures, whereas the efficiency of bubbling at 37 °C was reduced by greater than 50%. Morphologically, the WWOXf cell height or thickness was significantly increased during cell division or apoptosis, but the event did not occur in BCD. In comparison, when WWOXd cancer cells received UV or UV/cold shock, these cells underwent NO-independent POD. UV/cold shock effectively downregulated the expression of many proteins such as the housekeeping α-tubulin (> 70%) and β-actin (< 50%), and cortactin (> 70%) in WWOXf COS7 cells. UV/cold shock induced relocation of α-tubulin to the nucleus and nuclear bubbles in damaged cells. UV induced co-translocation of the WWOX/TRAF2 complex to the nuclei, in which the prosurvival TRAF2 blocked the proapoptotic WWOX via its zinc finger domain. Without WWOX, TRAF2 did not relocate to the nuclei. Cold shock caused the dissociation of the WWOX/TRAF2 complex in the nucleus needed for BCD. In contrast, the formation of the WWOX/TRAF2 complex, plus p53, was strengthened at 37 °C required for apoptosis.ConclusionsThe temperature-sensitive nuclear WWOX/TRAF2 complex acts as a molecular switch, whose dissociation favors BCD at low temperatures, and the association supports apoptosis at 37 °C in UV-treated WWOXf cells.

Cold Exposure Therapy Sensitizes Nanodrug-Mediated Radioimmunotherapy of Breast Cancer.

Cold exposure (CE) therapy can quickly induce tumor starvation by brown adipose tissue (BAT) thermogenesis. Exploring the combined antitumor mechanism of CE and traditional therapies (such as radiotherapy (RT)) is exciting and promising. In this study, we investigated the effect of CE in combination with nitric oxide (NO) gas therapy on sensitizing tumors to RT and promoting tumor radio-immunotherapy. We first constructed a liposome (SL) loaded with the NO prodrug S-nitroso-N-acetylpenicillamine (SNAP). When SL is injected, the glutathione (GSH) within the tumor region promotes the release of NO from SNAP. Subsequently, the superoxide anion produced by RT reacts with NO to generate peroxynitrite (ONOO-), which has strong oxidative properties and induces cell death. Meanwhile, the mice were exposed to a CE environment of 4 °C. CE-mediated BAT thermogenesis induced tumor starvation, which led to a decrease in ATP and GSH content within the tumor as well as an improvement in the hypoxic microenvironment and a decrease in myeloid-derived suppressor cells. All of the above have promoted the effectiveness of RT and activated the systemic antitumor immunity. In the bilateral tumor experiment, treatment of the primary tumor inhibited the growth of the distant tumor and promoted the infiltration of CD8+ T cells into the tumor. These findings reveal that the synergy of CE, NO gas therapy, and RT could confer high effective anticancer effects, providing possibilities in personalized cancer treatment.

Towards bespoke gas permeability by functionally graded structures in laser-based powder bed fusion of metals

Permeable, media transporting, components are an integral part in numerous technical applications. In gas turbines combustors, for example, gaseous oxidizer and fuel are transported separately into the burner, where they are injected and mixed, and subsequently combusted. The mixture homogeneity strongly affects the combustion performance and emissions formation and is, amongst other, determined by the spatial distribution of fuel injection ports. In this context, porous media provide the limiting case for a spatial distribution of media-injecting pores, yet is typically associated with a high pressure drop that yields a loss in efficiency. In this study, possibilities of achieving gas permeability in additively manufactured porous structures are investigated. The objective is to selectively functionalize the permeable layers for gaseous media supply with low pressure loss and, when needed, enable a targeted mixing of different gas streams. For this purpose, a laser-based powder bed fusion process (PBF-LB/M) was used in this study. It offers the opportunity to manufacture varying porosities inside complex monolithic metal parts. To produce the porous structures and to achieve gas permeability, the effect of scan rotation angle, hatch distance, build-up direction and length of the porous specimen is investigated. Due to the high temperatures present in combustion systems, the present work utilizes Inconel 718 material. The AM gas permeable specimen are experimentally characterized by means of surface topography, micro X-ray computed tomography (µXRCT) as well as flow and pressure loss test. The results show, that the AM process parameter provide effective control parameters to adjust the permeability. The strongest effect originates from the hatch distance for a given build-up direction. Depending on the scan rotation, the flow transitions from a turbulent pipe flow to a Darcy flow as present in conventional porous media. A structured alignment and connectivity of pores can be realized as evident in the µXRCT results, surface topography and the flow measurements. Residual powder, powder adhering to the pore walls and stochastic closure of pores or channels lead to deviations and need to be considered when designing respective parts. Nonetheless, the results further show that a directional dependence of the permeability and the build-up direction can be realized and controlled. Consequently, when considering the AM build-strategy in the design of components, this directed permeability can be functionalized in the generation of gas transporting and gas mixing layers separately by adjusting the AM processing parameter.

A Janus WSi2P2As2 monolayer: A promising material for detecting NO2 with excellent sensitivity, selectivity, reversibility, and humidity resistance

Realizing highly sensitive, selective, humidity-resistant, and reversible detection of hazardous gas molecules with low detection limit in the air environment at room temperature is essential. Herein, we predict a novel two-dimensional Janus WSi2P2As2 material and propose a NO2 gas sensor with excellent response, selectivity, humidity resistance, and reversibility based on WSi2P2As2, by employing density functional theory, statistical thermodynamic modeling, and the non-equilibrium Green’s function approach. The Janus WSi2P2As2 monolayer is a stable semiconductor with a direct band gap of 0.85 eV and an intrinsic out-of-plane dipole moment. We study the sensing properties of the Janus WSi2P2As2 monolayer towards several typical toxic gases (NO, NO2, NH3, SO2, and H2S). All the gas molecules are physically adsorbed on the surface. Different adsorption energies and electronic structures are found for the top- and bottom-surface adsorptions due to the intrinsic dipole of the Janus WSi2P2As2. The experimental viability is characterized by the adsorption density and the recovery time. The statistical estimation of the adsorption density shows that the oxide gases can be adsorbed practically even at ultra-low concentration of part per billion (ppb) at room temperature. The rapid natural desorption of these toxic gases at 300 K indicates the recyclability of the WSi2P2As2 material. Furthermore, we evaluate the sensing performance of the WSi2P2As2-based gas sensor by the conductance change. The sensor exhibits ultra-response of 374 % and excellent selectivity towards NO2 molecules. Importantly, the sensor remains operating with high performance in the humid environment and air environment. These results demonstrate that the Janus WSi2P2As2 is a promising gas-sensing material for the NO2 detection.

Airborne ultrafine particle concentrations and brain cancer incidence in Canada’s two largest cities

BackgroundMalignant brain tumours are rare, but are important to study because survival rates are low and few modifiable risk factors have been identified. Existing evidence suggests that outdoor ultrafine particles (UFPs) (particulate matter < 100 nm, sometimes referred to as nanoparticles) can deposit in the brain and could encourage initiation and progression of cancerous tumours, but epidemiological data are limited. MethodsHigh-resolution estimates of outdoor UFP concentrations and size were linked to residential locations of approximately 1.5 million people in Montreal and Toronto, Canada from 2001 to 2015. Cox proportional hazards models were used to estimate associations between annual average outdoor UFPs and malignant brain tumour incidence while adjusting for potential confounding factors including other outdoor air pollutants. FindingsIn total, 1400 incident brain tumour cases occurred during follow-up. Consistent positive associations were observed between long-term exposures to outdoor UFPs and brain tumour incidence with increased risk ranging from 10.5% (95% CI: −1.4, 24.0%) to 15.3% (95% CI: 0.4, 32.5%) per 10,000 particle/cm3 increase. Long-term exposures to oxidant gases, black carbon, or fine particulate matter (PM2.5) were not associated with increased brain tumour incidence. InterpretationOur results suggest that long-term exposures to outdoor UFPs are associated with an increased risk of developing malignant brain tumours. On an absolute scale, the magnitude of this risk translates into approximately 24 additional cases per year per 10,000 particle/cm3 increase in annual average outdoor UFPs in a hypothetical city of 3-million people. FundingCanadian Institutes of Health Research (CIHR) Foundation Grant and The United States Health Effects Institute (HEI).

Observation on Switching Properties of WO3-Based H2 Sensor Regulated by Temperature and Gas Concentration.

Transition metal oxide semiconductors have great potential for use in H2 sensors, but in recent years, the strange phenomena about gas-sensitive performance associated with their special properties have been more widely discussed in research. In some cases, the resistance of transition metal oxide gas sensors will emerge with some changes contrary to their intrinsic semiconductor characteristics, especially in gas sensor research of WO3. Based on the hydrothermal synthesis of WO3, our work focuses on the abnormal change of tungsten oxide resistance to different gases at low temperature (80-200 °C) and high temperature (above 200 °C). Through in situ FT-IR and in situ XPS, combined with density functional theory calculations, a new reasonable explanation of WO3 is proposed for the abnormal resistance change caused by temperature and the strange response due to gas concentration. The occurrence of these findings can be attributed to the synergistic effect resulting from the presence of two contributing factors. One of them is attributed to the alteration in the surface valence state of WO3 induced by gas, resulting in the reduction of W6+. The other one is due to the reaction between gas and adsorbed oxygen on the surface of WO3. This work presents a novel and rational concept for addressing the reaction mechanism between gas and transition metal oxide semiconductors, thereby paving the way for the development of highly efficient gas sensors based on transition metal oxide semiconductors.

Portable and Hand-Held Ammonia Gas Sensor Enables Noninvasive Prediagnosis of Helicobacter pylori Infection.

Disease diagnosis of Helicobacter pylori (Hp) through human exhaled breath analysis has attracted considerable attention. However, conventional methods, such as carbon 13 (13C) breath test and infrared spectrometers, are facing the challenge of achieving portability and reliability synchronously. Herein, we report a portable and hand-held Hp analyzer using a bimetallic PtRu@SnO2-based gas sensor for the prediagnosis of Hp infection, which is based on detecting ammonia (NH3) as a potential biomarker in exhaled breath. Owing to the surface functionalization through highly catalytically active bimetallic PtRu nanoparticles (NPs) prepared by a photochemical reduction strategy, the PtRu@SnO2-based sensor exhibits high sensitivity and selectivity toward trace-level (200 ppb) NH3 even at high-humidity surroundings (80% RH). Consequently, the designed portable and hand-held Hp analyzer makes the accurate determination of NH3 at 800 ppb in exhaled breath. The tuning of energy band structure and electrical characteristics and the catalytic modulation of NH3 oxidation by PtRu NPs are proposed to be the reasons behind the enhanced NH3 gas-sensing performance, as confirmed by in situ analysis using an online MKS MultiGas 2030 FTIR gas analyzer. This work paves the way for the prediagnosis of Hp infection using a metal oxide gas sensor.