Alginate Lyases from Marine Bacteria: An Enzyme Ocean for Sustainable Future

The cell wall of brown algae contains alginate as a major constituent. This anionic polymer is a composite of β-d-mannuronate (M) and α-l-guluronate (G). Alginate can be degraded into oligosaccharides; both the polymer and its products exhibit antioxidative, antimicrobial, and immunomodulatory activities and, hence, find many commercial applications. Alginate is attacked by various enzymes, collectively termed alginate lyases, that degrade glycosidic bonds through β-elimination. Considering the abundance of brown algae in marine ecosystems, alginate is an important source of nutrients for marine organisms, and therefore, alginate lyases play a significant role in marine carbon recycling. Various marine microorganisms, particularly those that thrive in association with brown algae, have been reported as producers of alginate lyases. Conceivably, the marine-derived alginate lyases demonstrate salt tolerance, and many are activated in the presence of salts and, therefore, find applications in the food industry. Therefore, this review summarizes the structural and biochemical features of marine bacterial alginate lyases along with their applications. This comprehensive information can aid in the expansion of future prospects of alginate lyases.     

A Novel Distachionate from Breynia distachia Treats Inflammations by Modulating COX-2 and Inflammatory Cytokines in Rat Liver Tissue

Breynia distachia is a plant of genus Breynia belonging to family Phyllanthaceae. This study was conducted to isolate and examine the anti-inflammatory attributes of the roots of Breynia distachia. Methanol extract from roots were prepared by simple maceration. For phytochemical studies, isolation, purification, structure elucidation, metal analysis, total phenolic content, and solubility test were done by chromatographic and spectroscopic techniques. Anti-inflammatory activity was evaluated by cotton pallet edema model and carrageenan paw edema model, and antioxidant potential was evaluated by DPPH, FRAP, and ABTS antioxidants assays. Metal analysis of BD.Me revealed the presence of Na > Mg > K > Mn > Fe = Zn in respective order. Four phytochemicals such as gallic acid, quercetin, sinapic acid, and p-coumaric acid are found in Breynia distachia. Quercetin is present in relatively larger quantity, and shows antioxidant activity by reducing the ferric iron to ferrous iron. Novel distachionate shows high antioxidant activity in ABTS assay by reducing reactive oxygen species. Quantitative or qualitative analysis performed by HPLC indicates the ascending peaks or presence of secondary products (metabolites) respectively. Histopathology analysis of liver, spleen, heart, and kidney was done, revealing mild inflammations in spleen and liver, and no cytotoxicity in heart and kidney. Oral administration of BD.Me and ditachionate significantly inhibits the carrageenan and cotton pellet-induced paw edema in 1st and 2nd h with (ns = p > 0.05) than control. After 3rd, 4th, 5th, and 6th h, BD.Me and ditachionate showed inhibition of paw edema in a highly significant (*** = p < 0.001) manner as compared to control. In cotton-pellet edema model, distachionate shows a %inhibition of 57.3% at a dose level of 5 mg/kg. Docking values obtained from distachionate-COX-2 complex suggest a potent inhibitor evaluated for this protein. The distachionate shows effective anti-inflammatory activity. Methanol extracts of roots showed significant lipoxygenase inhibitory activity by IC₅₀ values of 155.7 ± 0.55 and 132.9 ± 0.33 μg/mL. Data from various in vitro and in vivo models suggest that novel distachionate isolated from Breynia distachia shows strong antioxidant and anti-inflammatory activities; it should be further studied for the exploration of its medicinal potential.     

Characteristics of Periodontal Tissues in Prosthetic Treatment with Fixed Dental Prostheses

The objective of the present study was to investigate the effects of various types of fixed prostheses on periodontal tissues and explore the association of gingival biotype and gum recession in relation to prosthesis types. The study participants (N = 95) were divided into three groups based on the type of dental prosthesis: Group-I: cobalt-chrome (Co-Cr) ceramic prosthesis fabricated by the conventional method (n = 35); Group-II: consisted of patients with Co-Cr ceramic prostheses fabricated by a computer-aided design and computer aided manufacturing (CAD/CAM) technique (n = 30); and Group-III: zirconia-based prostheses fabricated by the CAD/CAM technique (n = 30). Following the use of prostheses, periodontal examinations were performed using the Community Periodontal Index (CPI) and Modified Approximal Plaque Index (MAPI). In addition, the gingival biotype was examined using a probe transparency method. The Statistical Package for the Social Sciences (SPSS), Version 20 (IBM Company, Chicago, IL, USA), was used to analyze the results, and the significance level was set at p = 0.05. It showed the MAPI results after the use of prosthetic rehabilitation for 12 months of periodontitis in 87.9% ± 15.4 of patients in Group-I, in 80.6% ± 17.97 in those in Group-II, and in 62.5% ± 21.4 in those in Group-III (p < 0.01). The CPI index results indicated a high prevalence of periodontal disease in all groups. The number of people with healthy periodontium constituted 17.1% of patients in Group-I, 24.2% in Group-II, and 37.1% in Group-III. Our study concluded that prosthetic treatment with periodontal diseases showed better outcomes while using dental prostheses fabricated by the CAD/CAM technique compared to the conventionally fabricated dental prostheses. The thin gingival biotype is more often associated with gingival recession than the thick biotype.     

Evaluation of 222Rn and 226Ra concentrations in cement and limestone of Sheikh Buddin Hill,Pezu, Pakistan using different techniques

Lucky Cement Factory, Pezu is using limestone of Sheikh Buddin Hills as a raw material in cement. Workers of the factory have direct and general public have indirect exposure to radiological hazard due to natural radionuclides present in limestone. To address the radiological hazards, limestone, mixed (limestone+clay) and cement samples were evaluate for concentrations of ²²²Rn and ²²⁶Ra using CR-39, RAD7 and HPGe detectors. Maximum mean values of ²²²Rn using CR-39 and RAD7 detectors were found 1447 ± 198 and 1416 ± 74 Bq.m^?3 in cement samples and minimum were found in 536 ± 122 and 525 ± 45 Bq.m^?3 limestone samples, respectively. Maximum mean value of radon exhalation rate of 12.28 ± 1.68 Bq.m^?2 h^?1 in cement samples was found below the world average value of 57.6 Bq.m^?2 h^?1. Maximum mean values of ²²⁶Ra measured by CR-39 and HPGe detectors were found 24.25 ± 3.35 and 23.6 ± 0.70 Bq.kg^?1 in cement samples and minimum were found in 8.98 ± 2.02 and 9.19 ± 0.40 Bq.kg^?1 limestone samples, respectively. A positive correlations (R² = 0.9714) using CR-39 and RAD7 detectors and (R² = 0.9573) using CR-39 and HPGe detectors were obtained for the concentrations of ²²²Rn and ²²⁶Ra, respectively. Maximum mean value of annual effective dose of 347.78 ± 47.58 µSv.y^?1 in cement samples was found below the world average value of 1100 µSv.y^?1.     

Defect‐Free Mixed‐Matrix Membranes with Hydrophilic Metal‐Organic Polyhedra for Efficient Carbon Dioxide Separation

Defect‐free mixed‐matrix membranes (MMMs) were prepared by incorporating hydrophilic metal‐organic polyhedra (MOPs) into cross‐linked polyethylene oxide (XLPEO) for efficient CO₂ separation. Hydrophilic MOPs with triethylene glycol pendant groups, which were assembled by 5‐tri(ethylene glycol) monomethyl ether isophthalic acid and Cu^II ions, were uniformly dispersed in XLPEO without particle agglomeration. Compared to conventional neat XLPEO, the homogenous dispersion of EG₃‐MOPs in XLPEO enhanced CO₂ permeability of MMMs. Upon increasing the amount of EG₃‐MOPs, the membrane performance such as CO₂/N₂ selectivity was steadily improved because of unsaturated Cu^II sites at paddle‐wheel units, which was confirmed by Cu K‐edge XANES and TPD analysis. Therefore, such defect‐free MMMs with unsaturated metal sites would contribute to enhance CO₂ separation performance.     

Modulating Cation Migration and Deposition with Xylitol Additive and Oriented Reconstruction of Hydrogen Bonds for Stable Zinc Anodes

Highly reversible plating/stripping in aqueous electrolytes is one of the critical processes determining the performance of Zn-ion batteries, but it is severely impeded by the parasitic side reaction and dendrite growth. Herein, a novel electrolyte engineering strategy is first proposed based on the usage of 100 mM xylitol additive, which inhibits hydrogen evolution reaction and accelerates cations migration by expelling active H₂O molecules and weakening electrostatic interaction through oriented reconstruction of hydrogen bonds. Concomitantly, xylitol molecules are preferentially adsorbed by Zn surface, which provides a shielding buffer layer to retard the sedimentation and suppress the planar diffusion of Zn²⁺ ions. Zn²⁺ transference number and cycling lifespan of Zn ∥ Zn cells have been significantly elevated, overwhelmingly larger than bare ZnSO₄. The cell coupled with a NaV₃O₈ cathode still behaves much better than the additive-free device in terms of capacity retention.     

Communication: Thermal rectification in liquids by manipulating the solid-liquid interface

Thermal rectification, the origin of which lies in modifying the thermal resistance in a nonlinear manner, could significantly improve the thermal management of a wide range of nano-devices (both electronic and thermoelectric), thereby improving their efficiencies. Since rectification requires a material to be inhomogeneous, it has been typically associated with solids. However, the structure of solids is relatively difficult to manipulate, which makes the tuning of thermal rectification devices challenging. Since liquids are more amenable to tuning, this could open up new applications for thermal rectification. We use molecular dynamics simulations to demonstrate thermal rectification using liquid water. This is accomplished by creating an inhomogeneous water phase, either by changing the morphology of the surface in contact with the liquid or by imposing an arbitrary external force, which in practice could be through an electric or magnetic field. Our system consists of a bulk fluid that is confined in a reservoir that is bounded by two walls, one hot and the other cold. The interfacial (Kapitza) thermal resistance at the solid-fluid interface and the density gradient of the bulk fluid both influence the magnitude of the thermal rectification. However, we find that the role of the interfacial resistance is more prominent than the application of an external force on the bulk fluid.     

Magnetohydrodynamic peristaltic flow of a hyperbolic tangent fluid in a vertical asymmetric channel with heat transfer

In the present paper we discuss the magnetohydrodynamic (MHD) peristaltic flow of a hyperbolic tangent fluid model in a vertical asymmetric channel under a zero Reynolds number and long wavelength approximation. Exact solution of the temperature equation in the absence of dissipation term has been computed and the analytical ex- pression for stream function and axial pressure gradient are established. The flow is analyzed in a wave frame of reference moving with the velocity of wave. The expression for pressure rise has been computed numerically. The physical features of pertinent parameters are analyzed by plotting graphs and discussed in detail.     

Peristaltic flow of a couple stress fluid under the effect of induced magnetic field in an asymmetric channel

The present paper investigates the peristaltic transport of a couple stress fluid in an asymmetric channel with the effect of the induced magnetic field. The exact solutions of momentum and the magnetic field equations have been calculated under the assumptions of long wave length and low but finite Reynolds number. The expression for pressure rise has been computed numerically using mathematics software Mathematica. The graphical results have been presented to discuss the physical behavior of various physical parameters of interest. Finally, the trapping phenomena have been discussed for various physical parameters.