Hierarchical pseudo-cubic hematite nanoparticle as formaldehyde sensor

To develop a low cost and scalable gas, sensor for the detection of toxic and flammable gases with fast response and high sensitivity is extremely important for monitoring environmental pollution. This work reports a facile method for preparing pseudo-cubic hierarchical α-Fe₂O₃ nanostructured materials as well as their implementation in gas sensor application. The α-Fe₂O₃ is developed using Fe(NO₃)₃ and ethylene glycol followed by a facile and one-step solvo-thermal reaction without subsequent heat treatment. The pseudo-cubic nanostructures were having an average edge length of 5–10 nm. The solvent played the role of ligand and synergistically affected olation and oxolation process along with dehydration to form final product. The sensor performance of α-Fe₂O₃ in the detection of toxic and flammable gases such as formaldehyde (HCHO), ethanol (C₂H₅OH), and carbon monoxide (CO) was evaluated. As-synthesized nanostructured hematite showed better sensing performance towards formaldehyde. The fabricated gas sensor showed temperature sensitivity sensing performance for the same gas. In addition, ethanol, formaldehyde vapours, and carbon monoxide gas-sensing properties were tested and the sensing performance of the synthesized material was found to be in the order of HCHO > C₂H₅OH > CO. This sensing performance is attributed to the large specific surface area of the pseudo-cubic nanoparticles.     

Microwave assisted hydrothermal synthesis of well-dispersed and thermally stable Ag@SnO2 core–shell nanocomposites for propane sensing applications

A simple microwave assisted hydrothermal precipitation (M–H) technique for the synthesis of Ag@SnO₂ core–shell structure nanoparticles (NPs) is reported. Ag NPs were synthesized via chemical reduction of metal salt followed by M–H deposition of tin dioxide shell for fabrication of monodispersed core–shell particles. The phase and morphology has been investigated by X-ray diffraction technique (XRD) and transmission electron microscopy (TEM) respectively. Ag@SnO₂ core–shell nanocomposites have shown distinct surface Plasmon spectrum in the range of 407–440 nm. The core–shell morphology is confirmed from the TEM images. XRD patterns have suggested the formation of silver and tin dioxide in the face-centered cubic and Cassiterite form respectively. Our investigations suggested that the formation of core–shell structure results in the enhanced thermal stability of the system. Synthesized material is used for the detection of propane gas. To understand the multi gas sensing ability and selectivity for detection of propane gas by Ag@SnO₂ core–shell materials based devices, Sinha–Tripathy soft-sensor model has been proposed.     

Effect of Sucrose on Fabrication of Ceramic Foams from Aqueous Slurries

Ceramic foams with porosity exceeding 90% were prepared by direct foaming and casting of aqueous suspensions containing cetyl trimethyl ammonium bromide (CTAB) as a foaming agent. Foaming of the suspensions, particularly with lower viscosity, was initially non-homogeneous but the foam appeared to homogenize with milling time. Addition of sucrose to ceramic suspensions resulted in lowering of the suspension viscosity, stabilized the foams by reducing drainage of the suspension, and minimized coalescence of bubbles leading to lower cell sizes in sintered foams. Ceramic foams prepared from sucrose based suspensions were strengthened to such an extent that foams with porosity above 90% could be machined in the green state.     

Design of a Low-Cost Thermal Dispersion Mass Air Flow (MAF) Sensor

There is a need for a low-cost sensor to be used in many practical applications, such as the control of the air–fuel ratio in combustion burners, which measures the mass flow rate of fluid. This paper focuses on the design, calibration, and testing of a mass flow sensor operating on the principle of thermal dispersion. The developed sensor implements a digital proportional-integral controller which regulates the body temperature of a heated element, recognized as a thermistor, located in the stream of the fluid flow to a constant difference with respect to the ambient air temperature. The power dissipated by this heated element was referenced to known mass flow rates of air to determine the relationship between the dissipated power and ambient temperature to the measured mass flow rate. The inclusion of air flow conditioners, which filtered unwanted debris and delivered a more laminar air flow, was imperative to the success of the design. The designed sensor was proven to measure the incoming mass air flow through a duct, in the presence of moderate disturbances in the intake air pipe and for a wide range of ambient air temperatures, with a maximum full-scale error of 5.5% and a range up to 80 kg/h.     

Standalone and ensemble-based machine learning techniques for particle Froude number prediction in a sewer system

Neural Computing and Applications - The hydraulic capacity of a channel is impacted due to sediment deposition in urban drainage and sewer system. As a result, the self-cleansing mechanism is a...     

Fortification by design: A rational approach to designing vitamin D delivery systems for foods and beverages

Over the past few decades, vitamin D deficiency has been recognized as a serious global public health challenge. The World Health Organization has recommended fortification of foods with vitamin D, but this is often challenging because of its low water solubility, poor chemical stability, and low bioavailability. Studies have shown that these challenges can be overcome by encapsulating vitamin D within well-designed delivery systems containing nanoscale or microscale particles. The characteristics of these particles, such as their composition, size, structure, interfacial properties, and charge, can be controlled to attain desired functionality for specific applications. Recently, there has been great interest in the design, production, and application of vitamin-D loaded delivery systems. Many of the delivery systems reported in the literature are unsuitable for widespread application due to the complexity and high costs of the processing operations required to fabricate them, or because they are incompatible with food matrices. In this article, the concept of “fortification by design” is introduced, which involves a systematic approach to the design, production, and testing of colloidal delivery systems for the encapsulation and fortification of oil-soluble vitamins, using vitamin D as a model. Initially, the challenges associated with the incorporation of vitamin D into foods and beverages are reviewed. The fortification by design concept is then described, which involves several steps: (i) selection of appropriate vitamin D form; (ii) selection of appropriate food matrix; (iii) identification of appropriate delivery system; (iv) identification of appropriate production method; (vii) establishment of appropriate testing procedures; and (viii) system optimization.     

Applications of polymeric adjuvants in studying autoimmune responses and vaccination against infectious diseases

Polymers as an adjuvant are capable of enhancing the vaccine potential against various infectious diseases and also are being used to study the actual autoimmune responses using self-antigen(s) without involving any major immune deviation. Several natural polysaccharides and their derivatives originating from microbes and plants have been tested for their adjuvant potential. Similarly, numerous synthetic polymers including polyelectrolytes, polyesters, polyanhydrides, non-ionic block copolymers and external stimuli responsive polymers have demonstrated adjuvant capacity using different antigens. Adjuvant potential of these polymers mainly depends on their solubility, molecular weight, degree of branching and the conformation of polymeric backbone. These polymers have the ability not only to activate humoral but also cellular immune responses in the host. The depot effect, which involves slow release of antigen over a long duration of time, using different forms (particulate, solution and gel) of polymers, and enhances the co-stimulatory signals for optimal immune activation, is the underlying principle of their adjuvant properties. Possibly, polymers may also interact and activate various toll-like receptors and inflammasomes, thus involving several innate immune system players in the ensuing immune response. Biocompatibility, biodegradability, easy production and purification, and non-toxic properties of most of the polymers make them attractive candidates for substituting conventional adjuvants that have undesirable effects in the host.