Constructing Adsorption Site-Enhanced Vo-BiOCl/rGO Heterostructures for Efficient Response to NO2/NH3 Gases at Room Temperature.

Real-time detection of harmful gases at room temperature has become a serious problem in public health and environmental monitoring. Two-dimensional materials with semiconductor properties BiOCl is a promising gas-sensitive material due to its large specific surface area and adjustable band gap as well as outstanding safety characteristics. However, limited by the weak gas adsorption sites and sluggish charge-transfer ability, the performance of BiOCl could not be fully exploited. Oxygen vacancy (Vo) engineering can introduce lattice defects, thereby significantly increasing the local charge density and enhancing the adsorption of gases, which is an effective strategy to enhance the gas-sensing performance. In this work, we composite BiOCl with a vacancy (Vo-BiOCl) and reduced graphene oxide (rGO) to construct a Vo-BiOCl/rGO heterostructure with enhanced gas adsorption sites. Experimental and theoretical calculations show that Vo can enhance the adsorption of gases and the introduction of rGO forms a high-quality heterostructure with BiOCl, which can effectively reduce the band gap of BiOCl and promote electron transfer, thereby improving the sensitivity of the sensor. Benefiting from above, Vo-BiOCl/rGO achieves the ability to detect low concentrations of NO2/NH3 at room temperature, with high sensitivity (55% at 1 ppm of NO2 and -28% at 1 ppm of NH3), fast response time (40 s at 1 ppm of NO2 and 2 s at 1 ppm of NH3), good stability (over 150 days), and fully recoverable gas sensitivity.

A Novel PMVK Variant Associated with Familial Porokeratosis.

BACKGROUND: Porokeratosis is a rare chronic progressive hypokeratotic skin disease, possibly related to the mevalonate pathway. Variations in four enzymes, including phosphomevalonate kinase (PMVK) may alter this pathway, ultimately leading to porokeratosis. OBJECTIVES: The aim of the study was to identify the causative gene variant of porokeratosis in a Chinese family and investigate its population frequency and pathogenicity. METHOD: In this study, Sanger sequencing was used to identify the gene variant causative of porokeratosis; its population frequency was investigated by polymerase chain reaction-restriction fragment length polymorphism in 4 patients and three normal individuals as well as in 100 normal unrelated controls; finally, the pathogenicity of the mutation and the associated structural changes were predicted. RESULTS: We identified a novel heterozygous missense variant, c.207G>T (p. Lys69Asn) in the PMVK gene. This variant was found in all patients but not in the normal individuals in this family or in the 100 controls. In silico analysis indicated that the variant was pathogenic; p.Lys69Asn changed the length of the α-helix and the hydrogen bond pattern compared with the wild-type protein. CONCLUSIONS: The novel variant c.207G>T (p. Lys69Asn) in the PMVK gene was the causative variant in this porokeratosis family. This finding provides further evidence for the genetic basis of this disease.

Transcriptome and Physiological Analysis of Rootstock Types and Silicon Affecting Cold Tolerance of Cucumber Seedlings.

Cucumbers grafted on rootstocks with different de-blooming capacity show varying levels of cold tolerance. The content of fruit bloom correlates with its silicon-metabolizing capacity, and rootstock grafting can alter not only the cold tolerance but also the silicon-metabolizing capacity of the scion. The molecular mechanisms responsible for resistance due to rootstocks and silicon and the pathway that affects cold tolerance, however, remain poorly understood. Therefore, we performed physiological and transcriptome analysis to clarify how rootstock types and silicon affect cold tolerance in cucumber seedlings. Then, we randomly selected eight differentially expressed genes (DEGs) for quantitative real time PCR (qRT-PCR) analysis to proof the reliability of the transcriptome data. The results showed that silicon can enhance the cold tolerance of cucumbers by boosting the phenylpropanoid metabolism, and rootstock grafting can boost the active oxygen scavenging ability and synthesis level of hormones in cucumbers and maintain the stability of the membrane structure to enhance cold tolerance. The difference in cold tolerance between the two rootstocks is because the cold-tolerant one has stronger metabolic and sharp signal transduction ability and can maintain the stability of photosynthesis, thereby contributing to the stability of the cellular system and enhancing tolerance to cold.

SnS2 Quantum Dot-Based Optoelectronic Flexible Sensors for Ultrasensitive Detection of NO2 Down to 1 ppb.

Transition-metal dichalcogenides (TMDs) have gained intense interest for their outstanding optoelectronic and electrochemical characteristics, utilized in versatile applications such as gas sensors and photodetectors. However, TMD-based chemiresistors suffer from poor sensitivity at ppb-level detection, and the experimental detection limit fails to reach 1 ppb. Herein, SnS2 QD/graphene nanoheterostructures as functional flexible sensors are fabricated for NO2 gas and light detection at room temperature. The semiconductor type of the nanohybrids can be shifted between p-type and n-type by adjusting the proportion of the components, both of which exhibit excellent gas-sensing properties. The ppb-level NO2 detection is realized even under room temperature with superior sensitivity (860% to 125 ppb), fast response (114 s), and recovery (166 s). It also demonstrates ultrahigh sensitivity and broadband photodetection in the visible region. The photoresponsivity can reach upto 2.08 × 103 A/W under blue light illumination and under room temperature. Especially, the influence of light illumination of different wavelengths and intensities on gas-sensing performance is studied. Red light (1 mW/cm2) greatly enhances the sensitivity up to 5.1 folds, and the device performs obvious response to NO2 at concentrations as low as 1 ppb. Ab initio density functional theory calculation and band theories are applied to explain the interaction of the components and the effect of the light excitation inducing charge carriers on gas-sensing equilibrium.

High Sensitivity, Humidity-Independent, Flexible NO2 and NH3 Gas Sensors Based on SnS2 Hybrid Functional Graphene Ink.

Here, a high sensitivity gas sensing ink based on sulfonated rGO (S-rGO) decorated with SnS2 is synthesized for room temperature NO2 and NH3 detection. This sensing ink demonstrated an excellent sensitivity to ppb-level NO2 (17% response to 125 ppb) and sub-ppm-level NH3 (11% response to 1 ppm). The unique absorption properties of SnS2 improve the sensitivity of S-rGO 4.2 and 55 times to NO2 and NH3, respectively. Besides, the superhydrophobicity of the SnS2 endows the sensor with exceptional immunity to high relative humidity (RH). Furthermore, the sensors exhibit negligible degradation to NO2 and less than 15% degradation to NH3 in a wide range of RH from 30 (ambient humidity) to 90%. More importantly, the obtained full-written ink can be applied to common substrates, such as glass, clothes, and paper, and maintain excellent performance after being bent and twisted by 180°.