We report the temperature-dependent photoluminescence (PL) properties of polymeric graphite-like carbon nitride (g-C3N4) and a methodology for the determination of quantum efficiency along with the ...activation energy. The PL is shown to originate from three different pathways of transitions: σ*–LP, π*–LP, and π*−π, respectively. The overall activation energy is found to be ∼73.58 meV which is much lower than the exciton binding energy reported theoretically but ideal for highly sensitive wide-range temperature sensing. The quantum yield derived from the PL data is 23.3%, whereas the absolute quantum yield is 5.3%. We propose that the temperature-dependent PL can be exploited for the evaluation of the temperature dependency of quantum yield as well as for temperature sensing. Our analysis further indicates that g-C3N4 is well-suited for wide-range temperature sensing.
A self-powered, broad band and ultrafast photodetector based on n+-InGaN/AlN/n-Si(111) heterostructure is demonstrated. Si-doped (n+ type) InGaN epilayer was grown by plasma-assisted molecular beam ...epitaxy on a 100 nm thick AlN template on an n-type Si(111) substrate. The n+-InGaN/AlN/n-Si(111) devices exhibit excellent self-powered photoresponse under UV–visible (300–800 nm) light illumination. The maximum response of this self-powered photodetector is observed at 580 nm for low-intensity irradiance (0.1 mW/cm2), owing to the deep donor states present near the InGaN/AlN interface. It shows a responsivity of 9.64 A/W with rise and fall times of 19.9 and 21.4 μs, respectively. A relation between the open circuit voltage and the responsivity has been realized.
Abstract
We, for the first time, provide the experimental demonstration on the band gap engineering of layered hexagonal SnSe
2
nanostructured thin films by varying the thickness. For 50 nm thick ...film, the band gap is ~2.04 eV similar to that of monolayer, whereas the band gap is approximately ~1.2 eV similar to that of bulk for the 1200 nm thick film. The variation of the band gap is consistent with the the theoretically predicted layer-dependent band gap of SnSe
2
. Interestingly, the 400–1200 nm thick films were sensitiveto 1064 nm laser iradiation and the sensitivity increases almost exponentiallly with thickness, while films with 50–140 nm thick are insensitive which is due to the fact that the band gap of thinner films is greater than the energy corresponding to 1064 nm. Over all, our results establish the possibility of engineering the band gap of SnSe
2
layered structures by simply controlling the thickness of the film to absorb a wide range of electromagnetic radiation from infra-red to visible range.
For millennia, people have cut and joined different plant tissues together through a process known as grafting. By creating a chimeric organism, desirable properties from two plants combine to ...enhance disease resistance, abiotic stress tolerance, vigour or facilitate the asexual propagation of plants. In addition, grafting has been extremely informative in science for studying and identifying the long-distance movement of molecules. Despite its increasing use in horticulture and science, how plants undertake the process of grafting remains elusive. Here, we discuss specifically the role of eight major plant hormones during the wound healing and vascular formation process, two phenomena involved in grafting. We furthermore present the roles of these hormones during graft formation and highlight knowledge gaps and future areas of interest for the field of grafting biology.
Consumers are increasingly interested in nutritious, safe and healthy muscle food products with reduced salt and fat that benefit their well-being. Hence, food processors are constantly in search of ...natural bioactive ingredients that offer health benefits beyond their nutritive values without affecting the quality of the products. Mushrooms are considered as next-generation healthy food components. Owing to their low content of fat, high-quality proteins, dietary fibre and the presence of nutraceuticals, they are ideally preferred in formulation of low-caloric functional foods. There is a growing trend to fortify muscle food with edible mushrooms to harness their goodness in terms of nutritive, bioactive and therapeutic values. The incorporation of mushrooms in muscle foods assumes significance, as it is favourably accepted by consumers because of its fibrous structure that mimics the texture with meat analogues offering unique taste and umami flavour. This review outlines the current knowledge in the literature about the nutritional richness, functional bioactive compounds and medicinal values of mushrooms offering various health benefits. Furthermore, the effects of functional ingredients of mushrooms in improving the quality and sensory attributes of nutritionally superior and next-generation healthier muscle food products are also highlighted in this paper.
Reactive Oxygen Species （ROS） are continuously produced as a result of aerobic metabolism or in response to biotic and abiotic stresses. ROS are not only toxic by-products of aerobic metabolism, but ...are also signalling molecules involved in several developmental processes in all organisms. Previous studies have clearly shown that an oxidative burst often takes place at the site of attempted invasion during the early stages of most plant-pathogen interac- tions. Moreover, a second ROS production can be observed during certain types of plant-pathogen interactions, which triggers hyper- sensitive cell death （HR）. This second ROS wave seems absent during symbiotic interactions. This difference between these two responses is thought to play an important signalling role leading to the establishment of plant defense. In order to cope with the deleterious effects of ROS, plants are fitted with a large panel of enzymatic and non-enzymatic antioxidant mechanisms. Thus,increasing numbers of publications report the characterisation of ROS producing and scavenging systems from plants and from microorganisms during interactions. In this review, we present the current knowledge on the ROS signals and their role during plant-microorganism interactions.
Highly porous materials, with large surface area and accessible space, variable chemical compositions, and porosity at different length scales, have captivated the attention of researchers in recent ...years as an important family of functional materials. Here, we report a novel approach to grow porous metal oxides (PMOs) by sequential elemental dealloying in which a highly mobile element gets dealloyed first under the thermal treatment (annealing) and facilitates the formation of PMOs. Subsequently, a chemiresistive sensor based on porous SnO2 was fabricated for humidity sensing at room temperature which shows a high sensitivity of 348 in a fully humid >99% relative humidity (RH) atmosphere with an accuracy of 1% RH change. In addition, the sensor is highly durable and reproducible. Eventually, the chemiresistive sensor has been exploited for electronic listening toward speaking, whistling, and breath monitoring. Overall, the results advocate the fabrication of PMOs and the development of resistive humidity sensors for electronic listening as well as for biomedical applications.
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•Un-doped and nitrogen-doped carbon nanotubes (NCNTs) were synthesized by one-step pyrolysis.•Zinc oxide (ZnO) thin films were deposited on glass and p-Si substrates by ...sputtering.•Linear (MSM) and non-linear (p-n juntion) devices were fabricated.•Responsivity of MSM device was improved ∼607-fold after deposition of NCNTs and PEDOT:PSS due to charge carrier transfer.•The p-n junction device showed a responsivity increment of ∼15-fold after NCNTs deposition in comparison to bare film.
Zinc oxide (ZnO) has been widely explored for UV detection despite its high exciton binding energy that can inhibit its photoresponse due to high probability of recombination. Here, we describe an approach that suppresses recombination and enhances the photoresponse via engineering of photo-induced charge transfer (PCT) in a linear MSM device Ag/ZnO/Ag and a non-linear p-Si/ZnO junction device. ZnO film when coated with carbon nanotubes (CNTs)/ nitrogen-doped CNTs (NCNTs) facilitates electron transfer and when coated with Poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS) facilitates hole transfer, which inhibits recombination, increasing its photocurrent between 275–400 nm. This is one of the interesting approaches to enhance the photoresponse of a material. The extent of PCT depends on the amount of CNTs/NCNTs and PEDOT:PSS. Photocurrent was found to increase by ∼362-fold and ∼607-fold for 365 nm wavelength when NCNTs and NCNTs along with PEDOT:PSS were used as the recombination inhibitor on ZnO thin film, respectively. The responsivity was found to be 153 mA/W and 10.5 A/W, respectively for the coated Ag/ZnO/Ag linear and p-Si/ZnO non-linear device configurations, under 365 nm illumination. The enhancement is ∼15-fold for the non-linear devices. Overall, this work paves the way for an elegant and inexpensive means to hugely enhance photoresponse via engineering the photo-induced charge transfer in linear and non-linear devices. Furthermore, in addition to the photocurrent, the dark current and hence, the conductivity can be engineered via the approach discussed here.
We report the fabrication of a robust graphene reinforced composite coating with excellent corrosion resistance by aqueous cathodic electrophoretic deposition (EPD). At optimum EPD conditions, a ...coating thickness of around 40nm is obtained at 10V and deposition time of 30s. The surface morphological characterization are carried out by scanning electron microscopy which clearly shows reduced graphene oxide (rGO) with sizes ranging from 1 to 2μm uniformly coated on the copper sheet. The composite coating is shown to significantly increase the resistance of the metal to electrochemical degradation. Tafel analysis confirms that the corrosion rate exhibited by composite coating is an order of magnitude lower than that of bare copper. It is expected that this simple EPD technique for producing a graphene-reinforced composite coating can open a new avenue especially for marine engineering materials where resistance to salt water is of paramount importance.
We have developed a fast and highly sensitive chemiresistive sensor based on the nanocomposite of polysaccharide (guar gum) and gold nanoparticles for the room temperature detection of ammonia in the ...range of 0.1 parts-per-quadrillion (ppq) to 75 000 parts-per-million (ppm). Sensor response, selectivity, and stability studies reveal excellent sensing of the nanocomposite. The room temperature operation under ambient conditions and the wide range sensing indicates that the composites can be explored for environmental as well as biomedical applications. We have for the first time quantified the ammonia level released from the urine and blood serum of human beings using the resisitive sensor. The urine ammonia level was found to be ∼24 000 ppm and is higher for patients with renal problems. This demonstrated the utility of the sensor for health monitoring.
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