Recent trends in chiral separations on immobilized polysaccharides CSPs

Polysaccharide CSPs are recognized widely in chiral chromatography but the introduction of immobilized phases (Chiralpak IA, Chiralpak IB and Chiralpak IC columns) is a remarkable achievement. The immobilized CSPs can be used with organic, normal and reversed phase modes; even with prohibited solvents too (tetrahydrofuran, chlorofom, dichloromethane, acetone, 1,4-dioxane, ethylacetate, and certain other ethers). Their susceptibilities to work with a wide range of solvents have increased the range of applications including chiral recognition mechanisms. Besides, these are also useful for monitoring the progress of stereo-specific reactions; normally need prohibited solvents. The present review describes the various aspects of commercial available immobilized chiral columns. Attempts have been made to discuss immobilized polysaccharides CSPs, immobilized vs coated CSPs, comparison of immobilized CSPs, method development, optimization, chiral recognition mechanism and applications. The chiral recognition capabilities of commercial columns were in the order of Chiralpak IA > Chiralpak IB > Chiralpak IC columns; but complimentary to each other. Of course, these CSPs are not fully developed and need more advancements and applications. Definitely, the future of immobilized CSPs is quite better. Hopefully, in the coming years they will be the choice of the chromatographers for chiral separations in liquid chromatography.     

Synthesis, characterization and antimicrobial investigation of mechanochemically processed silver doped ZnO nanoparticles

The application of nanomaterials has gained considerable momentum in various fields in recent years due to their high reactivity, excellent surface properties and quantum effects in the nanometer range. The properties of zinc oxide (ZnO) vary with its crystallite size or particle size and often nanocrystalline ZnO is seen to exhibit superior physical and chemical properties due to their higher surface area and modified electronic structure. ZnO nanoparticles are reported to exhibit strong bacterial inhibiting activity and silver (Ag) has been extensively used for its antimicrobial properties since ages. In this study, Ag doped ZnO nanoparticles were synthesized by mechanochemical processing in a high energy ball mill and investigated for antimicrobial activity. The nanocrystalline nature of zinc oxide was established by X-ray diffraction (XRD) studies. It is seen from the XRD data obtained from the samples, that crystallite size of the zinc oxide nanoparticles is seen to decrease with increasing Ag addition. Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) data also supported the nanoparticle formation during the synthesis. The doped nanoparticles were subjected to antimicrobial investigation and found that both increase in Ag content and decrease in particle size contributed significantly towards antimicrobial efficiency. It was also observed that Ag doped ZnO nanoparticles possess enhanced antimicrobial potential than that of virgin ZnO against the studied microorganisms of Escherichia coli and Staphylococcus aureus.     

Resolvability in circulant graphs

A set W of the vertices of a connected graph G is called a resolving set for G if for every two distinct vertices u, v ∈ V (G) there is a vertex w ∈ W such that d(u, w) ≠ d(v, w). A resolving set of minimum cardinality is called a metric basis for G and the number of vertices in a metric basis is called the metric dimension of G, denoted by dim(G). For a vertex u of G and a subset S of V (G), the distance between u and S is the number min s∈S d(u, s). A k-partition Π = {S 1 , S 2 , . . . , S k } of V (G) is called a resolving partition if for every two distinct vertices u, v ∈ V (G) there is a set S i in Π such that d(u, Si )≠ d(v, Si ). The minimum k for which there is a resolving k-partition of V (G) is called the partition dimension of G, denoted by pd(G). The circulant graph is a graph with vertex set Zn , an additive group of integers modulo n, and two vertices labeled i and j adjacent if and only if i-j (mod n) ∈ C , where CZn has the property that C =-C and 0 ■ C. The circulant graph is denoted by Xn, Δ where Δ = |C|. In this paper, we study the metric dimension of a family of circulant graphs Xn, 3 with connection set C = {1, n/2 , n-1} and prove that dim(Xn, 3 ) is independent of choice of n by showing that dim(Xn, 3 ) ={3 for all n ≡ 0 (mod 4), 4 for all n ≡ 2 (mod 4). We also study the partition dimension of a family of circulant graphs Xn,4 with connection set C = {±1, ±2} and prove that pd(Xn, 4 ) is independent of choice of n and show that pd(X5,4 ) = 5 and pd(Xn,4 ) ={3 for all odd n ≥ 9, 4 for all even n ≥ 6 and n = 7.     

Dynamic characteristics of nanoindentation in Ni:A molecular dynamics simulation study

In this work,three-dimensional molecular dynamics simulation is carried out to elucidate the nanoindentation behaviour of single crystal Ni.The substrate indenter system is modelled using hybrid interatomic potentials including the manybody potential(embedded atom method) and two-body Morse potential.The spherical indenter is chosen,and the simulation is performed for different loading rates from 10 m/s to 200 m/s.Results show that the maximum indentation load and hardness of the system increase with the increase of velocity.The effect of indenter size on the nanoindentation response is also analysed.It is found that the maximum indentation load is higher for the large indenter whereas the hardness is higher for the smaller indenter.Dynamic nanoindentation is carried out to investigate the behaviour of Ni substrate to multiple loading-unloading cycles.It is observed from the results that the increase in the number of loading unloading cycles reduces the maximum load and hardness of the Ni substrate.This is attributed to the decrease in recovery force due to defects and dislocations produced after each indentation cycle.     

A T‐shaped selenenyl halide

The title selenenyl halide complex, 3‐iodo‐2‐phenyl‐3H‐3‐selenaindazole, C₁₂H₉IN₂Se, has an almost planar conformation and a nearly ideal T‐shape for the Se(INC) moiety [Se—I 2.8122 (12), Se—C 1.881 (7) and Se—N2 2.051 (6) Å; C—Se—N 79.6 (3), C—Se—I 96.8 (2) and N—Se—I 176.17 (17)°]. This arrangement, together with the two selenium lone pairs, leads to a distorted trigonal‐bipyrimidal geometry about the Se atom. Intermolecular interactions are largely limited to stacking forces.     

Nigella sativa L. and COVID-19: A Glance at The Anti-COVID-19 Chemical Constituents,Clinical Trials,Inventions, and Patent Literature

COVID-19 has had an impact on human quality of life and economics. Scientists have been identifying remedies for its prevention and treatment from all possible sources, including plants. Nigella sativa L. (NS) is an important medicinal plant of Islamic value. This review highlights the anti-COVID-19 potential, clinical trials, inventions, and patent literature related to NS and its major chemical constituents, like thymoquinone. The literature was collected from different databases, including Pubmed, Espacenet, and Patentscope. The literature supports the efficacy of NS, NS oil (NSO), and its chemical constituents against COVID-19. The clinical data imply that NS and NSO can prevent and treat COVID-19 patients with a faster recovery rate. Several inventions comprising NS and NSO have been claimed in patent applications to prevent/treat COVID-19. The patent literature cites NS as an immunomodulator, antioxidant, anti-inflammatory, a source of anti-SARS-CoV-2 compounds, and a plant having protective effects on the lungs. The available facts indicate that NS, NSO, and its various compositions have all the attributes to be used as a promising remedy to prevent, manage, and treat COVID-19 among high-risk people as well as for the therapy of COVID-19 patients of all age groups as a monotherapy or a combination therapy. Many compositions of NS in combination with countless medicinal herbs and medicines are still unexplored. Accordingly, the authors foresee a bright scope in developing NS-based anti-COVID-19 composition for clinical use in the future.     

Tailoring the optical and magnetic properties of La-BaM hexaferrites by Ni substitution

We investigate the impact of Ni insertion on the structural,optical,and magnetic properties of Ba_0.8La_0.2Fe_12-xNi_xO₁₉hexaferrites(Ni substituted La-BaM hexaferrites).Samples were prepared using the conventional co-precipitation method and sintered at 1000℃for 4 hours to assist the crystallization process.An analysis of the structure of the samples was carried out using an x-ray diffraction(XRD)spectrometer.The M-type hexagonal structure of all the samples was confirmed using XRD spectra.The lattice parameters a and c were found to be in the ranges of 5.8925±0.001 nm–5.8952±0.001 nm and 23.2123±0.001 nm–23.2219±0.001 nm,respectively.The M-type hexagonal nature of the prepared samples was also indicated by the presence of corresponding FT-IR bands and Raman modes in the FT-IR and Raman spectra,respectively.EDX results confirmed the successful synthesis of the samples according to the required stoichiometric ratio.A UV-vis spectrometer was used to record the absorption spectra of the prepared samples in the wavelength range of 200 nm–1100 nm.The optical energy bandgap of the samples was found to be in the range of 1.21 eV–3.39 eV.The M–H loops of the samples were measured at room temperature at an applied magnetic field range of 0 kOe–60 kOe.A high saturation magnetization of 99.92 emu/g was recorded in the sample with x=0 at a microwave operating frequency of 22.2 GHz.This high value of saturation magnetization is due to the substitution of La3+ions at the spin-up(12k,2a,and 2b)sites.The Ni substitution is proven to be a potential candidate for the tuning of the optical and magnetic parameters of M-type hexaferrites.Therefore,we suggest that the prepared samples are suitable for use in magneto-optic applications.     

Antioxidant Activity Evaluation of FlexirubinType Pigment from Chryseobacterium artocarpi CECT 8497 and Related Docking Study

The current research is focused on studying the biological efficacy of flexirubin, a pigment extracted from Chryseobacterium artocarpi CECT 8497.Different methods such as DPPH, H₂O_2, NO^•, O₂^•−, ^•OH, lipid peroxidation inhibition by FTC and TBA, ferric reducing and ferrous chelating activity were carried out to evaluate the antioxidant activity of flexirubin. Molecular docking was also carried out, seeking the molecular interactions of flexirubin and a standard antioxidant compound with SOD enzyme to figure out the possible flexirubin activity mechanism. The new findings revealed that the highest level of flexirubin exhibited similar antioxidant activity as that of the standard compound according to the H₂O₂, ^•OH, O₂^•−, FTC and TBA methods. On the other hand, flexirubin at the highest level has shown lower antioxidant activity than the positive control according to the DPPH and NO• and even much lower when measured by the FRAP method. Molecular docking showed that the interaction of flexirubin was in the binding cavity of the SOD enzyme and did not affect its metal-binding site. These results revealed that flexirubin has antioxidant properties and can be a useful therapeutic compound in preventing or treating free radical-related diseases.     

A tandem ionic liquid-based dispersive microextraction method using in-syringe air-assisted vesicle system for rapid determination of lead and cadmium in artificial sweat extract of facial cosmetic products

In the present study an innovative tandem ionic liquid-based dispersive microextraction method using an in-syringe air-assisted vesicle system was developed to determine the ultra-trace levels of lead (Pb^II) and cadmium (Cd^II) ions in synthetic sweat extract of branded and nonbranded facial cosmetic products. This method is based on injecting 2-amino-3-sulfhydrylpropanoic acid (l -cysteine) (as an eco-friendly chelating agent), hexafluorophosphate ion [PF₆⁻] (as an ion pair agent) and 1-hexyl-3-methylimidazolium hexafluorophosphate [HMIM] [PF₆] (as an acceptor phase) into the synthetic sweat extract of facial cosmetic products (branded and nonbranded). The acceleration of the dispersion process was carried out by rapid pressure in the syringe through the back-and-forth movement of plunger. The sediment phase was removed following centrifugation, and then hydrophobic complexes of analyte were back-extracted into HNO₃ and finally injected into a flame atomic absorption spectrometer. Several factors were systematically optimized. The validity of the methodology was tested by analyzing spiked known standards of both metals in a real sample. The proposed method was applied to the artificial sweat extracts of face makeup products, indicating how much toxic metals from different cosmetics are directly absorbed into skin.