The magnetic recoverable ZnO/ZnFeO/diatomite (ZZFDT) composite was synthesized by hydrothermal-precipitation method. The structure, optical properties and magnetic properties of the composites were characterized by different analytical instruments. ZZFDT-1 is composed of cubic spinel, hexagonal wurtzite, tetrahedron structure. SEM and TEM showed that ZnO and ZnFeO particles were loaded onto the surface of diatomite, and the particle size was uniform. In addition, ZZFDT-1 is a typical mesoporous material with a specific surface area of 65.3 m/g and pore size of about 12 nm. The response range of ZZFDT-1 is extended to visible light, and the band gap is 1.5 eV. Moreover, the M-H hysteretic curves of ZZFDT-1 exhibited superparamagnetic properties. The photocatalytic activity of different samples was evaluated by the conversion rate of oxytetracycline (OTC) under visible light. ZZFDT-1 has the best photocatalytic activity and the conversion is up to 95%. Because of its magnetic nature, it can be easily separated from the solution. The results showed that the ZZFDT composite has good photocatalytic activity under visible light. After being reused six times, it still has good stability.

An amalgamation of microbiology, biocatalysis, recombinant molecular biology, and nanotechnology is crucial for groundbreaking innovation in developing nano-biomedicines and sensoristics. Enzyme-based nano-biosensor finds prospective applications in various sectors (environmental, pharmaceutical, food, biorefineries). These applications demand reliable catalytic efficiency and functionality of the enzyme under an extreme operational environment for a prolonged period. Over the last few years, bio-fabrication of nano-biosensors in conjunction with thermozymes from thermophilic microbes is being sought after as a viable design. Thermozymes are known for their robustness, are chemically resistant toward organic solvents, possess higher durability for constant use, catalytic ability, and stability at elevated temperatures. Additionally, several other attributes of thermozymes like substrate specificity, selectivity, and sensitivity make them desirable in developing a customized biosensor. In this review, crucial designing aspects of enzyme-based nano-biosensors like enzyme immobilization on an electrode surface, new materials derived from microbial sources (biopolymers based nanocomposites), improvisation measures for sensitivity, and selectivity have been addressed. It also covers microbial biosynthesis of nanomaterials used to develop sensoristic devices and its numerous applications such as wastewater treatment, biorefineries, and diagnostics. The knowledge will pave the way toward creating consistent eco-friendly, economically viable nanostructured-based technologies with broad applicability and exploitation for industrial use in the near future.

Sensors for rapid and reliable detection of biomolecules are crucial for clinical medical diagnoses. Here, a rapid, ultra-sensitive, magnetic-assisted biosensor based on resonance Raman scattering at MoS@FeO composite nanoflowers is presented. Raman shifts and X-ray photoelectron spectra indicated that the composite was formed via Fe-S covalent bonds. Convenient magnetic separations could be performed because of the superparamagnetic FeO nanoparticles. MoS E and A Raman peaks were used as probe signals for anti-interference immunoassays. The probe unit of the immunoassay also included goat anti-human IgG molecules that were used as the target analyte. Au substrates coupled with the goat anti-human IgG were used as capture units to form sandwich biosensors. Because of the magnetic enrichment, the detection limit was improved by three orders-of-magnitude and the detection time was reduced from 1.5 h to 1 min. Sandwich biosensors using MoS@FeO nanoflowers as Raman probes could be very promising sensors for proteins, antigens, and other immunogenic biopolymers, as well as for corpuscular viruses and cells.

Attributable to the rapid increase in human infection of Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the World Health Organization (WHO) has declared this disease outbreak as a pandemic. This outbreak can be tackled to some extent through proper management and early diagnosis. This work reports a biosensor based on vertical tunnel field-effect transistor (VTFET) developed for the detection of SARS-CoV-2 from the clinical samples through the analysis of its spike, envelope, and DNA proteins. Investigation of the sensitivity of the proposed sensor has been done by calculating the shift in drain current. The dielectric constant equivalent of the virus proteins is used to represent the hybridized biomolecules within the nanogaps. The sensitivity of this proposed sensor is found to be significantly high (order of 10) showing the viability of the device to be a superior sensor. Furthermore, the sensitivity analysis concerning DNA charge density is also performed. The effect of DNA charge density variation on the threshold voltage (V) and sensitivity have also been studied in this work. The proposed sensor is also investigated for its noise performance and observed the sensitivity with and without the effect of interface trap charges. Finally, the proposed sensor is benchmarked against the sensitivity of various FET-based biosensors already published earlier.

Studies on Mg substituted Zn-Cu ferrites with chemical formula of ZnCuMgFeO were synthesized by solid-state reaction technique. The structural phase of all the samples is characterized by XRD, show single phased cubic spinel structure. Density of the samples increases with the increase of Mg quantity. Average grain diameter decreases with increasing Mg content. All samples show soft ferromagnetic behavior as confirmed from the M-H hysteresis loop obtained from the VSM analysis. Thesaturation magnetization decreases with increasing Mg quantity. Increasing and decreasing trend of coercivity with the increase of Mg quantityis observed, which led to the slightly hard magnetic phase. The high frequencies create more effective for the ferrite grains of advanced conductivity and minor dielectric constant for all the samples but the AC electrical resistivity and dielectric constant are initiate to be more operational at lower frequencies. The variation of resistivity, dielectric constant with the Mg concentration is completely related to the porosity and bulk density.

In this study, using a thirsty plant extract and a simple hydrothermal method, a nano-probe was introduced to detect the phenobarbital based on fluorescence. Functional groups, particle size, surface morphology, and types of elements were identified using analysis such as FTIR, TEM, SEM, EDX, respectively. The excitation at 355 nm and emission intensity at 446 nm for nano-probe, the nano-probe shows that various parameters such as pH, temperature, and time were investigated for optimization conditions. After optimizing the factors affecting the sensor's response, a linear range between 0 and 750 µM with a detection limit of 5 µM was obtained. Then, the effect of interfering with other materials was investigated and finally, the ability of this sensor to measure the phenobarbital in real samples has been studied.

Recently the emissions of volatile organic compounds (VOCs) in the atmosphere have increased dramatically with rapid development of urbanization and industry. This led to a large decline in air quality around the world, which resulted in a heavy impact on human health. Therefore, new/cheap detection devices for VOCs are of high interest. Formaldehyde (FA) is a very toxic VOC, which damages the respiratory system even in the smallest doses and short exposure time. Zinc oxide (ZnO)/nickel oxide (NiO) heterostructures were synthesized using an economical route: firstly, NiO was prepared by liquid exfoliation technique and deposited by dip-coating on alumina ceramic transducers with two interdigital gold (Au) electrodes, followed by low-temperature hydrothermal growth of ZnO. The as-prepared sensors were characterized by atomic force microscopy (AFM), scanning electron microscopy (SEM-EDAX), and X-Ray fluorescence (XRF). The response/recovery of ZnO/NiO heterostructure-based microsensors for formaldehyde was investigated at room temperature, in agreement with modern sensing requirements. The sensor operating voltage was varied between 1.5 and 5.0 V direct current (DC), to achieve the best sensor performance.

A binary transition metal oxide containing nickel and iron (NiFeO) and hybridization of this nanomaterial with reduced graphene oxide (rGO) are synthesized by the hydrothermal method. X-ray diffraction (XRD) and Raman spectroscopy confirm the successful synthesis of these materials. Also, scanning electron microscope (SEM) and transmission electron microscope (TEM) images illustrated the particle morphology with the particle size of 20 nm. The synthesized material is then examined as a sensor on the surface of the glassy carbon electrode to detect a very small amount of rutin. Some electrochemical tests such as cyclic voltammetry, differential pulse voltammetry (DPV), and impedance spectroscopy indicate the remarkable accuracy of this sensor and its operation in a relatively wide range of concentrations of rutin (100 nM-100 µM). The accuracy of the proposed electrochemical sensors is approximately 100 nM in 0.1 M PBS, (pH = 3) which is relatively impressive and can be reported. Also, the stability rate after 100 DPV was about 95 %, which is a considerable and relatively excellent value. Considering the very good results, it seems that the NiFeO-rGO can be considered as a new proposal in the development of accurate and inexpensive electrochemical sensors.

Liquid-solid triboelectric nanogenerators (L-S TENGs) can generate corresponding electrical signal responses through the contact separation of droplets and dielectrics and have a wide range of applications in energy harvesting and self-powered sensing. However, the contact between the droplet and the electret will cause the contact L-S TENG's performance degradation or even failure. Here we report a noncontact triboelectric nanogenerator (NCLS-TENG) that can effectively sense droplet stimuli without contact with droplets and convert them into electrical energy or corresponding electrical signals. Since there is no contact between the droplet and the dielectric, it can continuously and stably generate a signal output. To verify the feasibility of NCLS-TENG, we demonstrate the modified murphy's dropper as a smart infusion monitoring system. The smart infusion monitoring system can effectively identify information such as the type, concentration, and frequency of droplets. NCLS-TENG show great potential in smart medical, smart wearable and other fields.

Novel chemi-resistive gas sensors with strong detection capabilities operating at room temperature are desirable owing to their extended cycle life, high stability, and low power consumption. The current study focuses on detecting NH at room temperature using lower gas concentrations. The co-precipitation technique was employed to produce pure and Al-doped ZnO nanoparticles, which were calcined at 300 °C for three hours. The effect of aluminium (Al) doping on the structural, morphological, optical, and gas-sensing abilities was investigated and reported. The presence of aluminium was confirmed by XRD, EDX, and FTIR spectroscopy. Additionally, to assess the various characteristics of Al-doped ZnO nanoparticles, scanning electron microscopy (SEM), ultraviolet-visible diffuse reflectance spectroscopy (UV-DRS), atomic force microscopy (AFM), and Brunauer-Emmett-Teller (BET) techniques were used. The crystallite size increased from 14.82 to 17.49 nm in the XRD analysis; the SEM pictures showed a flower-like morphology; and the energy gap decreased from 3.240 to 3.210 eV when Al doping was raised from 1 wt% to 4 wt%. AFM studies revealed topographical information with significant roughness in the range of 230-43 nm. BET analysis showed a mesoporous nature with surface areas varying from 25.274 to 14.755 m/g and pore diameters ranging from 8.34 to 7.00 nm. The sensing capacities of pure and Al-doped ZnO nanoparticles towards methanol (CHOH), toluene (CH), ethanol (CHOH), and ammonia (NH) were investigated at room temperature. The one-wt% Al-doped ZnO sensor demonstrated an ultrafast response and recovery times at one ppm compared to other AZO-based sensors towards NH.

For the first time, the influence of Cerium (Ce) on the structural, microstructural, Fourier infrared spectroscopy, and LPG sensing behaviour of CoCrCeO (CoCrCe) is described in this study. The solution combustion technique was used to create the CoCrCe samples. All samples were sintered for 3 h at 600 °C to achieve a pure crystalline nature free of impurities. The production of cubic spinel structures with typical crystallite sizes smaller than 16 nm is confirmed by X-ray diffraction. Because compressive lattice strain is created when Ce ions are replaced by Cr ions, we discovered reducing the lattice parameter. Further samples were analysed using the FTIR technique to learn about the octahedral and tetrahedral stretching bands, which confirmed the ferrite structure was free of impurities. Scanning Electron microscopy was used to examine the samples' microstructures. All of the samples were determined to be very porous. Elemental analysis was performed using energy dissipative spectra, which confirmed the presence of all elements in the samples. 2-mol% Ce has the best gas sensing characteristics of any Ce concentration. Furthermore, the thin film based on CoCrCeO may be employed as a chemiresistive gas sensor to detect LPG (10-1000 ppb) at room temperature. On LPG exposure, the constructed gas sensor demonstrates greater gas sensitivity in the order of 98% at 500 ppb, with higher stability, rapid response, and recovery time in the order of 60 s and 75 s, respectively. This study reports for the first time on the creation of an LPG gas sensor device that operates at room temperature and has high sensitivity. Because of their high gas sensitivity, rapid reaction and recovery times, and long-term stability, these material gas sensors might be ideal materials for the manufacture of gas sensors devices for the detection of LPG low concentration (ppb level).

The morphology-controlled synthesis of nanostructured photocatalysts by an environmentally friendly and low-cost method provides a feasible way to realize practical applications of photocatalysts. Herein, BiWO (BWO) nanophotocatalysts with mulberry shape, sheet-like, and round-cake morphologies have been successfully synthesized through a highly facile solvothermal process by simply adjusting the solvothermal temperature or utilizing selective addition of ethylene glycol as an orientation agent without using strong acids and bases and/or hazardous chemicals. The ratio of ethylene glycol and glacial acetic acid can affect the morphology and oxygen vacancy content of BWO, thereby influencing the photocatalytic performance. The photocatalytic activity of the as-prepared samples was evaluated by degradation of rhodamine B (RhB) and tetracycline under visible-light irradiation. The results indicated that all the BWO samples exhibited morphology-associated photocatalytic activity, and the sheet-like structure of BWO obtained via solvothermal treatment at 120 °C with ethylene glycol and glacial acetic acid ratio of 1:3 achieved the maximum specific surface area and possessed abundant oxygen vacancies, exhibiting outstanding photocatalytic activity for degradation of RhB and tetracycline. The degradation rate of RhB reached 100% within 20 min. To the best of our knowledge, this value is one of the most remarkable values for pristine BWO photocatalysts. Radical capture experiments demonstrated that hydroxyl radicals (·OH) play major roles compared with electrons (e) and holes (h) in the photocatalytic degradation process. A possible mechanism for the photocatalytic degradation of pollutants was proposed to better understand the reaction process. We believe that the more economical, efficient and greener methodology can provide guidance to develop highly efficient photocatalysts with favourable morphology and structure.

In this study, a facile synthesis of fluorescence carbon dots (CDs) from local oak apple (O-CDs) in the mountainous region of was performed through hydrothermal treatment. The characterization of O-CDs was carried out by SEM, TEM, FTIR, EDX, Mapping, lain scan, and AFM, respectively. In addition, the fluorescence of CDs was quenched by efavirenz with a linear concentration of 10 to 450 μM, associated with the limit of detection of 3 μM. Subsequently, the CDs were successfully applied for efavirenz probing in blood plasma environment.

Semiconductor ZnO aerogels were synthesized by a sol-gel process with different concentrations (2.5-7.5 wt.%) of Al (n-type) or Na (p-type) and dried under supercritical CO. The materials were calcined at 500 °C to remove the organic content and to crystallize the ZnO. The microstructure of the ZnO-based aerogels comprises a porous structure with hexagonal and platelet-shaped interconnected particles. The bandgap of the aerogels doped with Al decreased significantly compared to pure, undoped ZnO aerogels, while their specific surface area increased. For the electrical characterization of the ZnO-Na/ZnO-Al junctions, the doped ZnO aerogels were deposited on commercial glass substrates coated with indium tin oxide (ITO) by drop casting method. The I-V curves of the p-n homojuntions revealed a characteristic diode rectifying behavior.

Avalanche phenomenon uses critical pump power to produce extreme nonlinear behavior from small disturbances, and has gradually become known. Here, it is reported that the strong green up-conversion emission produced in NaBi(WO) phosphor by the positive feedback enhancement of the energy transfer process. The power dependence indicates that the photon avalanche process has occurred. Contrary to other up-conversion mechanisms, photon avalanche (PA) is a bifurcation phenomenon: avalanches occur above the critical excitation power. The experimental results are analyzed using the rate equation model. The high-response photon avalanche process produced by Yb and Ho ions is discussed in detail. The results show that PA can not only improve the brightness and efficiency of up-conversion, but also has a wider range of applications than traditional up-conversion materials, especially in the detection material of temperature sensor plays an important role.

Nowadays, hydrogels have been attracted a lot of interest due to their immense potential in different fields such as biomedicine and biotechnology. Biodegradable and biocompatible pH-sensitive chitosan-grafted polyacrylic acid (CTS-g-PAA) hydrogel was synthesized by grafting an acrylic acid monomer onto chitosan at the presence of methylene bisacrylamide as a cross-linking agent and ammonium persulphate as an initiator. FT-IR spectroscopy and scanning electron microscopy (SEM) were used to analyze the properties of the obtained hydrogel. The synthesized hydrogel is suitable for the delivery of many hydrophilic drugs or species. Using a multi-walled carbon nanotube modified-glassy carbon electrode (CNT-GCE), the loading and release conditions of Nile Blue (NB) as an electroactive compound were evaluated utilizing the differential pulse voltammetry (DPV) and cyclic voltammetry (CV). The effect of various parameters on the electrochemical signal of NB was investigated, and the optimal conditions for the efficient performance of hydrogel to delivery of NB were obtained. The electrocatalytic current values show linear dependence to NB concentration in the range of 0.098 - 0.971 μM while the detection limit of this electrochemical platform was 12.3 nM. The unique proposed hydrogel with the electroactive NB has a broad range of possible applications in biosensors for signal enhancement and bioanalysis.

In this work, various Cu, Ni, Ag-microalloyed Sn-5Sb/Cu joints, ordinary Sn-5Sb/Cu joints, and low-melting-point Sn-3Ag-0.5Cu (SAC305)/Cu (used for comparison) were prepared, focusing on the influence of Cu, Ni, and Ag on the microstructure evolution, interfacial IMC growth, and microhardness of Sn-5Sb/Cu joint under long-time isothermal aging process. Results showed that the microstructure of microalloyed joints consisted of β-Sn matrix, SbSn, and (Cu, Ni)Sn and AgSn compounds. (Cu, Ni)Sn compounds generated a coarsening effect in the aging microalloyed joints, yet its coarsening speed is significantly lower than the ordinary Sn-5Sb/Cu. Meanwhile, the total IMC layer thickness increased with the rising aging time. A single fine dendritic (Cu, Ni)Sn IMC at the interface of microalloyed joint was observed and evolved into a larger scallop or layer-like duplex IMCs ((Cu, Ni)Sn + CuSn) after the aging. Considering the combined effect of Cu, Ni, and Ag, the microalloyed joints exhibited the improved microstructure relative to ordinary counterparts and low-melting-point SAC305 materials, significantly inhibiting the interfacial IMC growth, especially CuSn. The CuSn IMC thickness and diffusion coefficient in the Sn-5Sb-0.5Cu-0.1Ni-0.5Ag/Cu joint were 0.71-2.81 μm and 0.96 × 10 μm·s, respectively. Besides, the precipitation strengthening mechanism triggered by the microalloyed elements was extremely obvious and the soldering and aging joints revealed superior microhardness values of 20-35 HV. This could effectively improve the application range of Sn-5Sb-based materials in higher-temperature package conditions such as third-generation semiconductors.

Among many chemical compounds synthesized for third-generation photovoltaic applications, quinoline derivatives have recently gained popularity. This work reviews the latest developments in the quinoline derivatives (metal complexes) for applications in the photovoltaic cells. Their properties for photovoltaic applications are detailed: absorption spectra, energy levels, and other achievements presented by the authors. We have also outlined various methods for testing the compounds for application. Finally, we present the implementation of quinoline derivatives in photovoltaic cells. Their architecture and design are described, and also, the performance for polymer solar cells and dye-synthesized solar cells was highlighted. We have described their performance and characteristics. We have also pointed out other, non-photovoltaic applications for quinoline derivatives. It has been demonstrated and described that quinoline derivatives are good materials for the emission layer of organic light-emitting diodes (OLEDs) and are also used in transistors. The compounds are also being considered as materials for biomedical applications.

In this work, we examined the double metal below ferroelectric layer FET that is double metal below negative capacitance field-effect transistor (DM-below-NCFET) for biosensing application and change in nanocavity gap with biomolecules as protein, (cholesterol oxidase), streptavidin, and uricase. For measuring the electrical characteristic and neutral biosensing such as threshold voltage, switching ratio () of the device which is higher than one without molecules by 1.52 times, sensitivity of protein enhanced by 1.11 over without biomolecule, limit of detection of protein is higher by 1.012 times over without molecule, shift in potential have been researched for cavity length 10 nm. The biosensor indicated improved sensitivity for biomolecules with the rise in their dielectric parameter. Moreover, modulation of the length of the gap of cavity was too examined, exposing that its increment (from 8 to 12 nm) altogether upgraded the sensitivity of the proposed biosensor. Visual TCAD (Technology Computer-Aided Design) software is used for simulating all results. In general, the consequences of this examination represent that such DM-below-NCFET biosensors can display extreme sensitivity (1.11) at small drain voltage (0.4 V), empowering their utilization for biosensor applications to analyze different infections which involve low power, extreme density, and enhanced speed.

Various nanoparticles have been developed for bio-applications. However, nanocomposites particles, (NCPs) with effective and ability to sensing cholesterol, are still needed. Herein, we present new cholesterol and pH-responsive NCPs as sensor particles to promote sensitivity. The traditional method of mixing and grinding was used to fabricate the oxides of magnesium and manganese MgO-MnO NCPs with different mixing ratios. Structural properties, detection of cholesterol, and pH sensitivity were examined. Results propped the high efficiency of MgO-MnO NCPs compared with individual oxides (MgO and MnO), low response time, while the analytical results confirmed the homogeneous structure of MgO-MnO NCPs. Particle size distribution results for NCPs were within 16.4 to 100 nm, which makes it promising in medical and bio-applications.

With the increasing miniaturization and power of optoelectronic devices, direct bonding of optical substrates like semiconductors and ceramics to metal heat sinks using low melting-point solder has gained significant interest. In this study, we demonstrated the bonding of glass to copper using Sn-58 wt% Bi solder (SB solder) doped with a small amount of rare earth (RE) elements. The RE elements act as active agents that facilitate the bonding to glasses without glass metallization. By optimizing the bonding parameters, such as reflow temperature and time, and employing an inert gas atmosphere to prevent solder or RE oxidation, we successfully achieved the highest shear strength in glass-copper solder joints using SB-RE solder, without the need for ultrasonic-assisted soldering (UAS). These results demonstrate the potential of using RE-containing solder for bonding unmetallized glass and ceramics in optoelectronic devices with metals at low soldering temperatures (< 200 °C). Furthermore, analysis of the shear strength and failure morphology of solder joints revealed only small degradation, primarily originating from the bulk solder region rather than the solder-glass interface, after both thermal aging (100 h) and cycling tests (100 cycles). The establishment of low-melting point RE-containing solders opens the possibility of direct jointing ceramic optoelectronic substrates to metal heat sinks for more efficient heat dissipation. In the meantime, our work also suggests that further optimization studies are necessary to explore its performance under more extreme working conditions.