Ni-doped ZnS nanoparticles are synthesized by simple hydrothermal process for the utilization in UV photodetectors. Surface morphology of the prepared samples is investigated through high resolution ...transmission electron microscopy (HRTEM), which reveals that the prepared nanoparticles are smaller than 20 nm. The well visualized selected area electron diffraction rings suggests the nanocrystalline nature of the prepared nanoparticles with (hkl) planes (111), (220) and (311). The structural analysis is done by x-ray diffraction (XRD) studies; which reveal the decrease in crystallite size with increase in Ni-doping concentration. The device performance of the photodetectors is tested under UV-A light (wavelength ≈365 nm) and found that the ability of the prepared devices increases with increase in Ni-doping concentration. This can be attributed to the enhanced surface to volume ratio and increase in charge carrier concentration. The adsorption-desorption of oxygen molecules on the nanoparticles' surface is considered to be the mechanism for UV photodetection.
•Synthesis of Ni-doped ZnS Nanoparticles.•Effect of Ni-doping on UV photodetection ability of ZnS nanoparticles.•Understanding UV photodetection mechanism through oxygen adsorption/desorption.
Most amino acid substitutions in a protein either lead to partial loss-of-function or are near neutral. Several studies have shown the existence of second-site mutations that can rescue defects ...caused by diverse loss-of-function mutations. Such global suppressor mutations are key drivers of protein evolution. However, the mechanisms responsible for such suppression remain poorly understood. To address this, we characterized multiple suppressor mutations both in isolation and in combination with inactive mutants. We examined six global suppressors of the bacterial toxin CcdB, the known M182T global suppressor of TEM-1 β-lactamase, the N239Y global suppressor of p53-DBD and three suppressors of the SARS-CoV-2 spike Receptor Binding Domain. When coupled to inactive mutants, they promote increased in-vivo solubilities as well as regain-of-function phenotypes. In the case of CcdB, where novel suppressors were isolated, we determined the crystal structures of three such suppressors to obtain insight into the specific molecular interactions responsible for the observed effects. While most individual suppressors result in small stability enhancements relative to wildtype, which can be combined to yield significant stability increments, thermodynamic stabilisation is neither necessary nor sufficient for suppressor action. Instead, in diverse systems, we observe that individual global suppressors greatly enhance the foldability of buried site mutants, primarily through increase in refolding rate parameters measured in vitro. In the crowded intracellular environment, mutations that slow down folding likely facilitate off-pathway aggregation. We suggest that suppressor mutations that accelerate refolding can counteract this, enhancing the yield of properly folded, functional protein in vivo.
Polypyrrole (PPy) nanomaterials have been synthesized with varying concentrations (10–40 mM) of anionic surfactant camphor sulphonic acid (CSA) using the chemical polymerization method, and then ...utilized for electromagnetic interference (EMI) shielding applications in the X-band of the microwave frequency range (8.2–12.4 GHz). An observable systematic change in the morphology of the prepared PPy has been noted, with highly aggregated globules transforming into fibular-like structures with an average diameter of approximately 80–120 nm as the CSA concentration increased. Raman and Fourier-transform infrared (FTIR) measurements indicate an increase in the relative intensities of the bipolaronic to polaronic bands, suggesting an improved conjugation of PPy with increasing CSA concentration. The electrical conductivity at room temperature has also been found to increase significantly, from 2.55 S/cm to 35.80 S/cm, as the concentration of CSA surfactant increased from 10 mM to 40 mM. Additionally, the shielding effectiveness (SE) for reflection (SE
R
), SE for absorption (SE
A
), and total SE (SE
T
) have been found to increase with increasing CSA concentration in PPy. The SE
T
values have been found exceeding 35 dB throughout the X-band of the microwave region in PPy nanomaterials with CSA concentrations ≥ 20 mM. It has been observed that CSA-directed polypyrrole exhibits high electrical conductivity, where the SE for absorption (SE
A
) dominates over the SE for reflection (SE
R
). This study suggests that the properties of PPy can be easily tailored for its potential utilization in the fabrication of various EMI shielding devices with improved performance.
Polyaniline (PAni) thin film has been synthesized using chemical oxidation route to be used as highly sensitive and selective ammonia (NH
3
) sensors. In situ dip-coating chemical polymerization ...method has been used to grow PAni thin films on glass substrates. The morphological and structural properties of deposited thin film have been examined by scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy and Fourier-transform infrared (FTIR) spectroscopy techniques. Raman and FTIR analysis confirm the successful growth of PAni with long-chain conjugation, whereas SEM micrograph reveals the growth of nanofibrous structured polyaniline. An amorphous structure of the prepared polyaniline with perpendicular periodicity of the conjugated polymer chains has been observed through XRD analysis. The ammonia gas sensing properties, in terms of change in electrical resistance, of the prepared thin film sensor have been investigated at room temperature for different concentrations (25–150 ppm) of ammonia. The deposited film has sensitivity as high as 245% and selectivity (%) of ~ 67% towards ammonia gas (at 150 ppm). The gas sensing response of the deposited film is found to be increased with increasing concentration of ammonia and the observed behaviour is well corroborated with modified Freundlich’s sensitivity versus chemical concentration relation. The effect of humidity on the sensing response and other parameters associated with the figure of merits of sensor like response time, recovery time, selectivity, stability etc. have also been studied. The compensation of charge carriers, i.e. polarons and bipolarons, under the electron donating ammonia gas is considered to be the mechanism of gas sensing for the deposited PAni film. The synthesized PAni thin film sensor with low cost, high sensitivity, selectivity and durability can be utilized for the development of industrial ammonia sensor.
Surface modification through electrical discharge machining (EDM) results in many advantages, such as improved surface hardness, enhanced wear resistance, and better micro-structuring. During ...EDM-based surface modification, either the eroding tool electrode or a powder-mixed dielectric can be utilized to add material onto the machined surface of the workpiece. The current study looks at the surface modification of H13 die steel using EDM in a dielectric medium mixed with graphite powder. The experiments were carried out using a Taguchi experimental design. In this work, peak current, pulse-on time, and powder concentration are taken into consideration as input factors. Tool wear rate (TWR), material removal rate (MRR), and the microhardness of the surface of the machined specimen are taken as output parameters. The machined surface’s microhardness was found to have improved by 159%. The results of X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDS) analysis and changes in MRR and TWR due to the powder-mixed dielectric are also discussed in detail.
•Sintering temperature greatly influence the electrical properties of BaBi4Ti4O15.•Optimum sintering condition identified for high resistivity, density and piezoelectric properties.•Influence of dc ...conductivity on dielectric dispersion has been analyzed.•Analysis with Lorentz type relation describes well the diffuseness and polarization process.•Frequency dependent peaks in ac conductivity near Tm imply relaxor-like behavior.
Barium bismuth titanate (BaBi4Ti4O15) ceramics prepared by conventional solid-state reaction method have been characterized, and influence of sintering temperature is shown to greatly affect the electrical properties. Formation of a single phase composition with orthorhombic structure and a randomly oriented plate-like microstructure is confirmed. Raman spectroscopy reveals broad over-damped low frequency modes indicating structural disorder. Room temperature dielectric response in the low frequency range (10−2–10Hz) reveals the influence of dc conductivity on dielectric dispersion. Analysis in terms of Lorentz type relation describes well the diffuseness in the dielectric data, and indicates only one polarization process in the system. The well fitting of frequency dependent maximum temperature (Tm) in ε′(T) to the non-linear Vogel–Fulcher equation and a similar trend in temperature dependent ac conductivity imply a relaxor-like nature of the material. Sintering at 1050°C for 5h is found to be favorable and yields ceramics with high density, high resistivity (4.6×1012Ωcm), low dielectric loss (tanδ∼0.05), remnant polarization (Pr=3.63μC/cm2) and a high piezoelectric charge coefficient, d33=24pC/N.
The aldo-keto reductase 1C3 (AKR1C3) isoform plays a vital role in the biosynthesis of androgens and is considered an attractive target in prostate cancer (PCa). No AKR1C3-targeted agent has to date ...been approved for clinical use. Flufenamic acid and indomethacine are non-steroidal anti-inflammatory drugs known to inhibit AKR1C3 in a non-selective manner as COX off-target effects are also observed. Recently, we employed a scaffold hopping approach to design a new class of potent and selective AKR1C3 inhibitors based on a N-substituted hydroxylated triazole pharmacophore. Following a similar strategy, we designed a new series focused around an acidic hydroxybenzoisoxazole moiety, which was rationalised to mimic the benzoic acid role in the flufenamic scaffold. Through iterative rounds of drug design, synthesis and biological evaluation, several compounds were discovered to target AKR1C3 in a selective manner. The most promising compound of series (6) was found to be highly selective (up to 450-fold) for AKR1C3 over the 1C2 isoform with minimal COX1 and COX2 off-target effects. Other inhibitors were obtained modulating the best example of hydroxylated triazoles we previously presented. In cell-based assays, the most promising compounds of both series reduced the cell proliferation, prostate specific antigen (PSA) and testosterone production in AKR1C3-expressing 22RV1 prostate cancer cells and showed synergistic effect when assayed in combination with abiraterone and enzalutamide. Structure determination of AKR1C3 co-crystallized with one representative compound from each of the two series clearly identified both compounds in the androstenedione binding site, hence supporting the biochemical data.
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•New AKR1C3 inhibitors were obtained using hydroxybenzoisoxazoles scaffolds.•X-ray was used for experimentally identify the binding mode in the AKR1C3 active site.•Seven compounds were assayed for AKR1C3 selectivity and cell-based activities.•Cpd 6 was found more then 460 time more selective on C3 compared to C2 AKR1 isoform.
Many pathogenic bacteria utilise sialic acids as an energy source or use them as an external coating to evade immune detection. As such, bacteria that colonise sialylated environments deploy specific ...transporters to mediate import of scavenged sialic acids. Here, we report a substrate-bound 1.95 Å resolution structure and subsequent characterisation of SiaT, a sialic acid transporter from Proteus mirabilis. SiaT is a secondary active transporter of the sodium solute symporter (SSS) family, which use Na
gradients to drive the uptake of extracellular substrates. SiaT adopts the LeuT-fold and is in an outward-open conformation in complex with the sialic acid N-acetylneuraminic acid and two Na
ions. One Na
binds to the conserved Na2 site, while the second Na
binds to a new position, termed Na3, which is conserved in many SSS family members. Functional and molecular dynamics studies validate the substrate-binding site and demonstrate that both Na
sites regulate N-acetylneuraminic acid transport.
Fabrication of n-TiO
2
/p-Si heterojunction devices for the fast solar-blind self-powered ultraviolet photodetectors has been reported. To produce these devices, n-type TiO
2
thin films of thickness ...50 nm and 200 nm have been deposited by radiofrequency magnetron sputtering technique on p-type silicon substrates. X-ray diffraction (XRD) studies reveal the growth of anatase phase of TiO
2
and the scanning electron microscopy (SEM) studies confirm the deposition of rod-like nanostructures of TiO
2
of length about 10 μm and diameter 1 μm. The current-voltage (I-V) characteristics of the prepared heterojunction devices demonstrate the non-ohmic diode like behavior. The obtained values of ideality factor from I-V characteristics for both the devices are greater than 2, which suggest a trap states assisted space charge limited current (SCLC) conduction of charge transport. The I-V characteristics recorded under the illumination of UV-A radiations (λ ≈ 365 nm), demonstrate the photo-diode like behavior of the fabricated devices. The transient photoresponse of the fabricated devices of thickness 50 nm and 200 nm of TiO
2
films, recorded under zero bias conditions are as high as ~795% and 180% respectively. The response and recovery times less than unity suggest the fast photodetection ability of the fabricated devices for the next generation photodetectors.
Differential Equation (DE) of fractional-order specifically gives clear view of fractional-order systems. Since genuine processes are typically or most anticipated to be fractional, employing ...fractional-order’s concept might be results to take us closer to the actual world. A lot of recent publications concentrate on employing fractional-order dynamics is to describe actual physical processes. In this paper, fractional calculus is applied in the field of control systems. Fractional-order controller also known as FOC has been proposed in numerous studies. The fundamental benefit of a FOC is that it gives the control mechanism of greater flexibility of time and frequency responses, enabling better and more reliable functioning of the system. The industrialization of fractional-order control has practical benefits of better solutions for control problems. The industrial controller has the requirement of different gains and orders of fractionalorder controllers. The selectable improved design is proposed, and an optimal and efficient controller is suggested with fractional-order approach. The results show that the best controller is selected from different controllers for water tank and bio-reactor systems. It is found in the results that the Mod FPID controller has the least overshoot of 4.31% and the fastest settling time of 76.5 s for water tank system and fractional-order controller (PID)
n
is selected for bio-reactor control systems.
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