Biological synthesis of silver nanoparticles using Senna auriculata flower extract for antibacterial activities.

In this study, biological synthesis of silver nanoparticles (AgNPs) using Senna auriculata flower extract for antibacterial activities was reported. The silver spectra compared to the plant extract show a rightward shift in AgNP peaks, indicating successful nanoparticle formation. The absorption band at 302 nm and the disappearance or shift of other peaks further confirm the synthesis. X-ray diffraction (XRD) analysis reveals that the AgNPs synthesized with S. auriculata extract have an average crystallite size of 25 nm. Transmission electron microscopy (TEM) results exhibited a polydispersed, spherical shape with sizes ranging from 70 nm, in clear contrast to the electron microscope image that showed their spherical shape. When examining the selected area electron diffraction (SAED) image, a specific set of lattice planes was correlated with a specific spot. A histogram of AgNP particle size distribution can be seen. AgNPs were tested against four different strains of bacteria for their antibacterial effectiveness, including gram negative bacteria (Escherichia coli, Klebsiella pneumoniae, and Staphylococcus aureus), as well as gram positive bacteria (S. aureus, d. Bacillus subtilis), at various concentrations of AgNP. The results of in vitro experiments indicate that AgNPs containing S. auriculata flowers inhibit amylase well. At two concentrations, ~16.03% and ~70.99%, AgNPs inhibit the reaction at low and high concentrations, respectively.

A Novel Membrane-like 2D A'-MoS2 as Anode for Lithium- and Sodium-Ion Batteries.

Currently, new nanomaterials for high-capacity lithium-ion batteries (LIBs) and sodium- ion batteries (SIBs) are urgently needed. Materials combining porous structure (such as representatives of metal-organic frameworks) and the ability to operate both with lithium and sodium (such as transition-metal dichalcogenides) are of particular interest. Our work reports the computational modelling of a new A'-MoS2 structure and its application in LIBs and SIBs. The A'-MoS2 monolayer was dynamically stable and exhibited semiconducting properties with an indirect band gap of 0.74 eV. A large surface area, together with the presence of pores resulted in a high capacity of the A'-MoS2 equal to ~391 mAg-1 at maximum filling for both Li and Na atoms. High adsorption energies and small values of diffusion barriers indicate that the A'-MoS2 is promising in the application of anode material in LIBs and SIBs.

Fabrication and Characterization of Au-Decorated MCM-41 Mesoporous Spheres Using Laser-Ablation Technique.

This study reports the synthesis of Au-decorated MCM-41 mesoporous nanoparticles using a laser-ablation technique. It was observed that the number of Au attached to MCM-41 nanostructures was dependent on the amount of encapsulated Cationic surfactant (cetyl ammonium bromide (CTAB) volume. The chemical group of the prepared nanoparticles was analyzed by FT-IR spectroscopy, where different absorption peaks corresponding to Au and MCM-41 were observed. The observed band region was ∼1090, 966, 801, 2918, and 1847 cm-1 for different samples, clearly confirming the successful preparation of MCM-41 with CTAB and Au-decorated MCM-41 nanoparticles using environmentally friendly laser-ablation approach. The surface morphology of the prepared nanoparticles were performed using TEM techniques. The TEM analysis of the MCM-41 specimen showed silica spheres with an average size of around 200 nm. Furthermore, Raman spectroscopy was done to evaluate the chemical structure of the prepared nanoparticles. It was seen that the prepared Au NPs decorated the MCM-41 system facilitated strong Raman peaks of CTAB. In addition, eight distinct Raman peaks were observed in the presence of Au NPs. This new functionalized method using the laser-ablation approach for mesoporous nanoparticles will participate effectively in multiple applications, especially the encapsulated molecule sensing and detection.

Management of Latent Tuberculosis Infection in Saudi Arabia: Knowledge and Perceptions Among Healthcare Workers.

Background Tuberculosis (TB) continues to pose a serious threat to public health despite great efforts. For many years, management and screening for active TB cases have been the main focus of TB control programs. Latent TB is a stage where TB can be prevented and controlled. Therefore, designing a comprehensive TB control program that includes latent tuberculosis infection (LTBI) management diseases is needed to be implemented among the healthcare workers (HCWs) who have been found to be at a higher risk for active TB compared to the general population. The objective of the study The objective of the study is to assess the knowledge and perceptions of LTBI among HCWs. In addition to estimating the prevalence of LTBI among HCWs using closed-end questions in a self-administered questionnaire. Subjects and methods Through a cross-sectional study and non-random sampling technique, 324 (84%) healthcare workers who met the inclusion criteria completed and submitted the electronic questionnaire. Results Among all participants, the study reported a good knowledge about LTBI; however, a third of HCWs had poor knowledge about the difference between LTBI and active TB. Eighteen percent of participants were diagnosed with LTBI, and two-thirds accepted the treatment. Of all participants who started the treatment, 55% completed the treatment course. The compliance rate was high among young HCWs and physicians who had a short course of LTB treatment regimen.  Conclusion The study reported a low acceptance and completion rate of LTBI therapy among HCWs. Low knowledge about some clinical facts of LTBI, the long duration of treatment, and being the treatment optional in Saudi health institutes were all barriers to accepting and completing the treatment of LTBI. All of these factors need to be addressed to increase the compliance rate to LTBI treatment.

Novel Copper-Zinc-Manganese Ternary Metal Oxide Nanocomposite as Heterogeneous Catalyst for Glucose Sensor and Antibacterial Activity.

A novel copper-zinc-manganese trimetal oxide nanocomposite was synthesized by the simple co-precipitation method for sensing glucose and methylene blue degradation. The absorption maximum was found by ultraviolet-visible spectroscopy (UV-Vis) analysis, and the bandgap was 4.32 eV. The formation of a bond between metal and oxygen was confirmed by Fourier Transform Infrared Spectroscopy (FT-IR) analysis. The average crystallite size was calculated as 17.31 nm by X-ray powder diffraction (XRD) analysis. The morphology was observed as spherical by scanning electron microscope (SEM) and high-resolution transmission electron microscopy (HR-TEM) analysis. The elemental composition was determined by Energy Dispersive X-ray Analysis (EDAX) analysis. The oxidation state of the metals present in the nanocomposites was confirmed by the X-ray photoelectron spectroscopy (XPS) analysis. The hydrodynamic diameter and zeta potential of the nanocomposite were 218 nm and -46.8 eV, respectively. The thermal stability of the nanocomposite was analyzed by thermogravimetry-differential scanning calorimetry (TG-DSC) analysis. The synthesized nanocomposite was evaluated for the electrochemical glucose sensor. The nanocomposite shows 87.47% of degradation ability against methylene blue dye at a 50 µM concentration. The trimetal oxide nanocomposite shows potent activity against Escherichia coli. In addition to that, the prepared nanocomposite shows strong antioxidant application where scavenging activity was observed to be 76.58 ± 0.30, 76.89 ± 0.44, 81.41 ± 30, 82.58 ± 0.32, and 84.36 ± 0.09 % at 31, 62, 125, 250, and 500 µg/mL, respectively. The results confirm the antioxidant potency of nanoparticles (NPs) was concentration dependent.

Recent Progress, Challenges, and Trends in Polymer-Based Sensors: A Review.

Polymers are long-chain, highly molecular weight molecules containing large numbers of repeating units within their backbone derived from the product of polymerization of monomeric units. The materials exhibit unique properties based on the types of bonds that exist within their structures. Among these, some behave as rubbers because of their excellent bending ability, lightweight nature, and shape memory. Moreover, their tunable chemical, structural, and electrical properties make them promising candidates for their use as sensing materials. Polymer-based sensors are highly utilized in the current scenario in the public health sector and environment control due to their rapid detection, small size, high sensitivity, and suitability in atmospheric conditions. Therefore, the aim of this review article is to highlight the current progress in polymer-based sensors. More importantly, this review provides general trends and challenges in sensor technology based on polymer materials.

Phyto Synthesis of Manganese-Doped Zinc Nanoparticles Using Carica papaya Leaves: Structural Properties and Its Evaluation for Catalytic, Antibacterial and Antioxidant Activities.

The current study aims to synthesize bimetal oxide nanoparticles (zinc and manganese ions) using the carica papaya leaf extract. The crystallite size of the nanoparticle from X-ray diffraction method was found to be 19.23 nm. The nanosheet morphology was established from Scanning Electron Microscopy. Energy-dispersive X-ray diffraction was used to determine the elemental content of the synthesized material. The atomic percentage of Mn and Zn was found to be 15.13 and 26.63. The weight percentage of Mn and Zn was found to be 7.08 and 10.40. From dynamic light scattering analysis, the hydrodynamic diameter and zeta potential was found to be 135.1 nm and -33.36 eV. The 1,1-diphenyl-2-picryl hydroxyl radical, hydroxyl radical, FRAP, and hydrogen peroxide scavenging tests were used to investigate the antioxidant activity of Mn-Zn NPs. Mn-Zn NPs have substantial antioxidant properties. The photocatalytic activity of the Mn-Zn NPs was assessed by their ability to degrade Erichrome black T (87.67%), methyl red dye (78.54%), and methyl orange dye (69.79%). Additionally, it had significant antimicrobial action S. typhi showed a higher zone of inhibition 14.3 ± 0.64 mm. Mn-Zn nanoparticles were utilized as a catalyst for p-nitrophenol reduction. The bimetal oxide Mn-Zn NPs synthesized using C. papaya leaf extract exhibited promising dye degradation activity in wastewater treatment. Thus, the aforementioned approach will be a novel, low cost and ecofriendly approach.

Atomically resolved structure of ligand-protected Au9 clusters on TiO2 nanosheets using aberration-corrected STEM.

Triphenylphosphine ligand-protected Au9 clusters deposited onto titania nanosheets show three different atomic configurations as observed by scanning transmission electron microscopy. The configurations observed are a 3-dimensional structure, corresponding to the previously proposed Au9 core of the clusters, and two pseudo-2-dimensional (pseudo-2D) structures, newly found by this work. With the help of density functional theory (DFT) calculations, the observed pseudo-2D structures are attributed to the low energy, de-ligated structures formed through interaction with the substrate. The combination of scanning transmission electron microscopy with DFT calculations thus allows identifying whether or not the deposited Au9 clusters have been de-ligated in the deposition process.

Phosphine-stabilised Au9 clusters interacting with titania and silica surfaces: the first evidence for the density of states signature of the support-immobilised cluster.

Chemically made, atomically precise phosphine-stabilized clusters Au9(PPh3)8(NO3)3 were deposited on titania and silica from solutions at various concentrations and the samples heated under vacuum to remove the ligands. Metastable induced electron spectroscopy was used to determine the density of states at the surface, and X-ray photoelectron spectroscopy for analysing the composition of the surface. It was found for the Au9 cluster deposited on titania that the ligands react with the titania substrate. Based on analysis using the singular value decomposition algorithm, the series of MIE spectra can be described as a linear combination of 3 base spectra that are assigned to the spectra of the substrate, the phosphine ligands on the substrate, and the Au clusters anchored to titania after removal of the ligands. On silica, the Au clusters show significant agglomeration after heat treatment and no interaction of the ligands with the substrate can be identified.