Novel liquid crystals with bulky terminal groups for ferroelectric displays in nanotechnology

The field of liquid crystals has become the focus of extensive research over the last century in terms of the design, synthesis and evaluation of novel materials, and the development of high technology applications, particularly displays. Virtually all current liquid crystal displays are based on the nematic phase, however, ferroelectric liquid crystal displays based on the chiral smectic C phase offers many advantages such as faster switching, higher resolution and contrast, bistability and wider angles of view. Although ferroelectric microdisplays are a commercial success, the technology is currently severely limited in their applicability because of problems in aligning the molecules in the ideal so-called bookshelf configuration. A wide range of novel materials has been designed, synthesized and evaluated. The main feature of the molecular design is the inclusion of a bulky group as part of a terminal chain, designed to cause a phase separation and preclude layer shrinkage on formation of the smectic C phase, and hence generate the desired bookshelf alignment. The synthesis was affected most efficiently using a range of synthetic methods, in particular low temperature lithiations and Suzuki coupling reactions. The materials were evaluated for structure and purity, and for mesomorphic and physical properties. The majority of the novel materials exhibit the smectic C phase over a wide temperature range, some compounds generate solely the smectic C phase whereas other additionally show the smectic A and nematic phases, and these results helps to establish patterns of how the mesomorphism relates to the structure of the bulky terminal group. Selected novel compounds were mixed with an established ferroelectric host mixture (KCHM211) to generate a range of novel ferroelectric host mixtures, which were doped with an established chiral dopant (BE8OF2N) to generate a range of novel ferroelectric mixtures, which were evaluated for their ferroelectric properties, namely tilt angle and spontaneous polarization. The results in terms of synthesis, mesomorphism and ferroelectric properties are discussed comparatively between novel compounds and known compounds

A novel inhibitor of SARS-CoV infection: Lactulose octasulfate interferes with ACE2-Spike protein binding

The ongoing challenge of managing coronaviruses, particularly SARS-CoV-2, necessitates the development of effective antiviral agents. This study introduces Lactulose octasulfate (LOS), a sulfated disaccharide, demonstrating significant antiviral activity against key coronaviruses including SARS-CoV-2, SARS-CoV, and MERS-CoV. We hypothesize LOS operates extracellularly, targeting the ACE2-S-protein axis, due to its low cellular permeability. Our investigation combines biolayer interferometry (BLI), isothermal titration calorimetry (ITC)-based experiments with in silico studies, revealing LOS's ability to reduce SARS-CoV-2's RBD's affinity for ACE2 in a dose-dependent manner, and bind tightly to ACE2 without inhibiting its enzymatic activity. Gaussian accelerated molecular dynamics simulations (GaMD) further supported these findings, illustrating LOS's potential as a broad-spectrum antiviral agent against current and future coronavirus strains, meriting in vivo and clinical exploration

Condition optimization of eco-friendly RP-HPLC and MCR methods via Box–Behnken design and six sigma approach for detecting antibiotic residues

Abstract A precise, Eco-friendly, and highly sensitive RP-HPLC method was employed using quality-by-design principles to concurrently identify cephalexin and cefixime residues in the manufacturing machines using a hypersil BDS C18 column (250 × 4.6 mm, 5 μm) at wavelength 254 nm. The Box–Behnken design was applied to obtain the best chromatographic conditions with the fewest possible trials. Three independent factors viz organic composition, flow rate, and pH were used to assess their effects on the responses' resolution and retention time. Overlay plot and desirability functions were implemented to predict responses of the high resolution and relatively short retention time using a mobile phase composed of acidic water: acetonitrile (85:15, v/v) at pH 4.5 adjusted by phosphoric acid with a flow rate of 2.0 mL/min. The spectral overlapping of the drugs was successfully resolved by the mean centering ratio (MCR) spectra approach at 261 nm and 298 nm for cephalexin and cefixime, respectively. Good linearity results were obtained for the suggested HPLC and MCR methods over the concentration range of (0.05–10 ppm) and (5–30 ppm) with a detection limit of 0.003, 0.004, 0.26, and 0.23 ppm, and quantitation limits of 0.008, 0.013, 0.79, and 0.68 ppm for cephalexin and cefixime, respectively, with a correlation coefficient of ≥ 0.9998 and good swab recovery results of 99–99.5%. A process capability index was accomplished for chemical and micro results, illustrating that both are extremely capable. The suggested method was effectively validated using ICH recommendations

Sustainable PVP-Capped Silver Nanoparticles as a Free-Standing Nanozyme Sensor for Visual and Spectrophotometric Detection of Hg²⁺ in Water Samples: A Green Analytical Method

In the proposed method, microwave-assist heating and AgNO3/trisodium citrate were used to create the polyvinylpyrrolidone-capped silver nanoparticles (PVP-AgNPs) sensor. This sensor had a peroxidase-like activity that could catalytically oxidize O-phenylenediamine (OPD, colourless) into 2,3-diaminophenazine (ox-OPD, greenish-yellow colour) in the presence of H2O2, otherwise, in the presence of Hg2+, this pass has been effectively inhibited. The degree of colour fading was directly correlated with Hg2+ concentration. These results indicated the selectivity of Hg2+ ions toward PVP-AgNPs after establishing the PVP-AgNPs/OPD/H2O2 system. This selectivity was proved by the negative results obtained from other mon-, di-, and trivalent ions such as Na+, K+, Ca2+, Mg2+, Ba2+, Co2+, Ni2+, Cd2+, and Cr3+, instead of Hg2+. Consequently, a reliable, selective, and eco-effective spectrophotometric approach was designed for the detection of Hg2+ in various types of water samples. LOD was extended to lower than 0.1 µM, and a fading in the obtained colour was shown by the naked eye at a concentration higher than 1.5 µM of Hg2+. The elemental details for preparing the used PVP-AgNPs, such as particle size, morphology, polydispersity index (PdI), and their UV-visible spectrum, were identified by SEM technique, TEM, UV-visible spectrophotometer, and zeta-sizer device. Thus, the peroxidase mimicking the activity of OPD/H2O2 was confirmed by a fluorescence technique. The greenness profile of this work was confirmed after applying a reported assessment tool

Sustainable PVP-Capped Silver Nanoparticles as a Free-Standing Nanozyme Sensor for Visual and Spectrophotometric Detection of Hg2+ in Water Samples: A Green Analytical Method

In the proposed method, microwave-assist heating and AgNO3/trisodium citrate were used to create the polyvinylpyrrolidone-capped silver nanoparticles (PVP-AgNPs) sensor. This sensor had a peroxidase-like activity that could catalytically oxidize O-phenylenediamine (OPD, colourless) into 2,3-diaminophenazine (ox-OPD, greenish-yellow colour) in the presence of H2O2, otherwise, in the presence of Hg2+, this pass has been effectively inhibited. The degree of colour fading was directly correlated with Hg2+ concentration. These results indicated the selectivity of Hg2+ ions toward PVP-AgNPs after establishing the PVP-AgNPs/OPD/H2O2 system. This selectivity was proved by the negative results obtained from other mon-, di-, and trivalent ions such as Na+, K+, Ca2+, Mg2+, Ba2+, Co2+, Ni2+, Cd2+, and Cr3+, instead of Hg2+. Consequently, a reliable, selective, and eco-effective spectrophotometric approach was designed for the detection of Hg2+ in various types of water samples. LOD was extended to lower than 0.1 µM, and a fading in the obtained colour was shown by the naked eye at a concentration higher than 1.5 µM of Hg2+. The elemental details for preparing the used PVP-AgNPs, such as particle size, morphology, polydispersity index (PdI), and their UV-visible spectrum, were identified by SEM technique, TEM, UV-visible spectrophotometer, and zeta-sizer device. Thus, the peroxidase mimicking the activity of OPD/H2O2 was confirmed by a fluorescence technique. The greenness profile of this work was confirmed after applying a reported assessment tool

Polyaniline-Supported Nickel Oxide Flower for Efficient Nitrite Electrochemical Detection in Water

A modified electrode with conducting polymer (Polyaniline) and NiO nanoflowers was prepared to detect nitrite ions in drinking water. A simple method was used to prepare the NiO nanoflower (NiOnF). Several techniques characterized the as-prepared NiOnF to determine the chemical structure and surface morphology of the NiO, such as XRD, XPS, FT-IR, and TGA. The activity of the electrode toward nitrite sensing was investigated over a wide range of pH (i.e., 2 to 10). The amperometry method was used to determine the linear detection range and limit. Accordingly, the modified electrode GC/PANI/NiOnf showed a linear range of detection at 0.1–1 µM and 1–500 µM. At the same time, the limit of detection (LOD) was 9.7 and 64 nM for low and high concentrations, respectively. Furthermore, the kinetic characteristics of nitrite, such as diffusion and transport coefficients, were investigated in various media. Moreover, the charge transfer resistance was utilized for nitrite electrooxidation in different pH values by the electrochemical impedance technique (EIS). The anti-interfering criteria of the modified surfaces were utilized in the existence of many interfering cations in water (e.g., K+, Na+, Cu2+, Zn2+, Ba2+, Ca2+, Cr2+, Cd2+, Pd2+). A real sample of the Nile River was spiked with nitrite to study the activity of the electrode in a real case sample (response time ~4 s). The interaction between nitrite ions and NiO{100} surface was studied using DFT calculations as a function of adsorption energy

Ag/ZnO Thin Film Nanocomposite Membrane Prepared by Laser-Assisted Method for Catalytic Degradation of 4-Nitrophenol

Zinc oxide thin film (ZnO thin film) and a silver-doped zinc oxide nanocomposite thin film (Ag/ZnO thin film) were prepared by the technique of the pulsed laser deposition at 600 °C to be applicable as a portable catalytic material for the removal of 4-nitrophenol. The nanocomposite was prepared by making the deposition of the two targets (Zn and Ag), and it was analyzed by different techniques. According to the XRD pattern, the hexagonal wurtzite crystalline form of Ag-doped ZnO NPs suggested that the samples were polycrystalline. Additionally, the shifting of the diffraction peaks to the higher angles, which denotes that doping reduces the crystallite size, illustrated the typical effect of the dopant Ag nanostructure on the ZnO thin film, which has an ionic radius less than the host cation. From SEM images, Ag-doping drastically altered the morphological characteristics and reduced the aggregation. Additionally, its energy band gap decreased when Ag was incorporated. UV spectroscopy was then used to monitor the catalysis process, and Ag/ZnO thin films had a larger first-order rate constant of the catalytic reaction K than that of ZnO thin film. According to the catalytic experiment results, the Ag/ZnO thin film has remarkable potential for use in environmentally-favorable applications

The Synergistic Effects of Sonication and Microwave Processing on the Physicochemical Properties and Phytochemicals of Watermelon (Citrullus lanatus) Juice

In recent years, consumers have increasingly demanded nutritious, healthy, and fresh-like food products with high organoleptic quality. Watermelon is rich in water, which is 92% mandatory for body functioning, and contains several vitamins, amino acids, antioxidants, carotenoids, and lycopenes with various health benefits. The present study examines the combined effect of ultrasound (US) and microwave (MW) on the physico-chemical and phytochemicals of watermelon juice during storage (up to 120 days). Sonication was employed for different time intervals, particularly from 2 to 8 min at 20 kHz frequency and 525 W power, while microwave was applied at two different time intervals (1 min 50 s and 2 min) at 1000 W power and a frequency of 2450 MHz. The product was stored at 4 °C up to 120 days for further examination. Our results revealed that treatment T5 (10 min ultrasound & 1 min 50 s microwave) manifested the maximum cloud value (3.00), acidity (0.15%), vitamin C content (202.67 mg/100 mL), phenolics (852.57 mgGAE/100 mL), flavonoids (1970.9 µg CE/100 mL), and total antioxidant activity (8650.3 µg equivalent of ascorbic acid/mL of juice). Sonication in combination with microwave proved to be an efficient technique for increasing the antioxidant potential of watermelon juice. Thus, US and MW treatments may be incorporated for enhancing the phytochemical release and shelf life of watermelon juice

Photocatalytic Performance Improvement by Doping Ag on ZnO/MWCNTs Nanocomposite Prepared with Pulsed Laser Ablation Method Based Photocatalysts Degrading Rhodamine B Organic Pollutant Dye

ZnO/MWCNTs nanocomposite has significant potential in photocatalytic and environmental treatment. Unfortunately, its photocatalytic efficacy is not high enough due to its poor light absorbance and quick recombination of photo-generated carriers, which might be improved by incorporation with noble metal nanoparticles. Herein, Ag-doped ZnO/MWCNTs nanocomposite was prepared using a pulsed laser ablation approach in the liquid media and examined as a degradable catalyst for Rhodamine B. (RhB). Different techniques were used to confirm the formation of the nanostructured materials (ZnO and Ag) and the complete interaction between them and MWCNTs. X-ray diffraction pattern revealed the hexagonal wurtzite crystal structure of ZnO and Ag. Additionally, UV-visible absorption spectrum was used to study the change throughout the shift in the transition energies, which affected the photocatalytic degradation. Furthermore, the morphological investigation by a scanning electron microscope showed the successful embedding and decoration of ZnO and Ag on the outer surface of CNTs. Moreover, the oxidation state of the formed final nanocomposite was investigated via an X-ray photoelectron spectrometer. After that, the photocatalytic degradations of RhB were tested using the prepared catalysts. The results showed that utilizing Ag significantly impacted the photo degradation of RhB by lowering the charge carrier recombination, leading to 95% photocatalytic degradation after 12 min. The enhanced photocatalytic performance of the produced nanocomposite was attributed to the role of the Ag dopant in generating more active oxygen species. Moreover, the impacts of the catalyst amount, pH level, and contact time were discussed

Utilization of Corncob as an Immobilization Matrix for a Xylanolytic Yeast Strain

Immobilization of microbial cells for the production of industrially important enzymes has been reported to offer the advantages of recyclability, higher yields and cost effectiveness. The search for an appropriate matrix that is affordable and easy to prepare is a significant topic in microbial biotechnology. Here, an abundant type of agro-industrial waste—corncob—was utilized as an immobilization matrix for the production of xylanase from an indigenous yeast strain, Saccharomyces cerevisiae MK-157. This is the first report describing xylanase production from immobilized S. cerevisiae. To render the corncob matrix more porous, alkaline pretreatment was undertaken and yeast cells were immobilized on the matrix by cultivating at 30 °C for 48 h in Sabouraud dextrose broth. After incubation, the immobilized matrix was transferred to mineral salt medium containing 1% xylan and incubated at 30 °C for 24 h. Xylanase production was determined in cell-free culture supernatant and the matrix was recycled for up to seven cycles. Moreover, xylanase-mediated saccharification was carried out using sugarcane bagasse as a substrate and the release of reducing sugars was monitored. The results showed that the immobilized yeast produced 4.97 IU mL−1 xylanase in the first production cycle, indicating a >tenfold increase compared to the free cells. Xylanase production further increased to its maximum levels (9.23 IU mL−1) in the fourth production cycle. Nonetheless, the cells retained 100% productivity for up to seven cycles. The volumetric and specific productivity of xylanase were also the highest in the fourth cycle. Scanning electron microscopy images revealed the rough surface of the untreated corncob, which became more porous after alkaline pretreatment. Immobilized yeast cells were also visible on the corncob pieces. The saccharification of a natural resource—sugarcane bagasse—using xylanase preparation yielded 26 mg L−1 of reducing sugars. Therefore, it can be concluded that yeast strains can yield sufficient quantities of xylanase, allowing possible biotechnological applications. Moreover, corncob can serve as a cost-effective matrix for industrially important yeast strains