Elastic Surface Model For Beta‐Barrels: Geometric,Computational, And Statistical Analysis

Over the past 2 decades, many different geometric models were created for beta barrels, including, but not limited to: cylinders, 1‐sheeted hyperboloids, twisted hyperboloids, catenoids, and so forth. We are proponents of an elastic surface model for beta‐barrels, which includes the minimal surface model as a particular case, but is a lot more comprehensive. Beta barrel models are obtained as numerical solutions of a boundary value problem, using the COMSOL Multiphysics Modeling Software. We have compared them against the best fitting statistical models, with positive results. The geometry of each individual beta barrel, as a rotational elastic surface, is determined by the ratio between the exterior diameter and the height. Through our COMSOL computational modeling, we created a rather large variety of generalized Willmore surfaces that may represent models for beta barrels. The catenoid is just a particular solution among all these shapes.     

Vitamin K, 2,3-Epoxide And Quinone Reduction: Mechanism And Inhibition

The chemical and enzymatic pathways of vitamin K₁ epoxide and quinone reduction have been investigated. The reduction of the epoxide by thiols is known to involve a thiol-adduct and a hydroxy vitamin K enolate intermediate which eliminates water to yield the quinone. Sodium borohydride treatment resulted in carbonyl reduction generating relatively stable compounds that did not proceed to quinone in the presence of base. NAD(P)H:quinone oxidoreductase (DT-diaphorase. E.C. I.6.99.2) reduction of vitamin K to the hydroquinone was a significant process in intact microsomes. but 1/5th the rate of the dithiothreitol (DTT)-dependent reduction. No evidence was found for DT-diaphorase catalyzed reduction of vitamin K₁ epoxide, nor was it capable of mediating transfer of electrons from NADH to the microsomal epoxide reducing enzyme. Purified diaphorase reduced detergent- solubilized vitamin K, 10^?5 as rapidly as it reduced dichlorophenylindophenol(DCPIP). Reduction of 10 μM vitamin K, by200 μM NADH was not inhibited by 10μM dicoumarol. whereas DCPIP reduction was fully inhibited. In contrast to vitamin K, (menadione). vitamin K₁ (phylloquinone) did not stimulate microsomal NADPH consumption in the presence or absence of dicoumarol. DTT-dependent vitamin K epoxide reduction and vitamin K reduction were shown to be mutually inhibitory reactions. suggesting that both occur at the same enzymatic site. On this basis, a mechanism for reduction of the quinone by thiols is proposed. Both the DTT-dependent reduction of vitamin K₁ epoxide and quinone. and the reduction of DCPIP by purified DT-diaphorase were inhibited by dicoumarol, warfarin. lapachol. and sulphaquinoxaline     

Apparatus Composition, Growth, And Survivorship Of The Lower Ordovician Conodont paracordylodus Gracilis Lindström, 1955

Analysis of numerous conodont element clusters from the Lower Ordovician cherts of the Burubaital Formation in central Kazakhstan reveals that the apparatus of Paracordylodus gracilis Lindstro¨m, 1955 consisted of 15 elements: two M elements, nine S elements (including 1 S₀), and four P elements (2 P₁, 2 P₂). The clusters probably originated as faecal pellets, but the best preserved indicate that the architecture of the apparatus of P. gracilis was comparable to that of ozarkodinid conodonts, providing strong support for the hypothesis that the 15-element 2M-9S-4P apparatus plan was plesiomorphic for conodonts with morphologically complex elements. All the elements within the P. gracilis clusters appear to be at a similar stage of ontogeny, and there is no evidence for late addition or replacement of elements. Analysis of element growth suggests that the relative dimensions of some elements changed during ontogeny, but the available data support the hypothesis that the growth of the apparatus as a whole was isometric. The size distribution of P. gracilis in the Burubaital Formation suggests that individuals in a particular size range were preferentially selected for consumption by predators. The identity of these predators is unknown, but they may have included other P. gracilis .     

Synthesis And Biological Activity Of Substituted 4H-1,4-Benzothiazines,Their Sulfones,And Ribofuranosides

The present article describes the synthesis of new 4H-1,4-benzothiazines via condensation and oxidative cyclization of substituted 2-aminobenzenethiols with β-diketones/β-ketoesters in dimethyl sulfoxide. The oxidation of these synthesized 4H-1,4-benzothiazines with 30% hydrogen peroxide in glacial acetic acid yielded 4H-1,4-benzothiazine sulfones and the reaction of these synthesized benzothiazines with sugar (β-D-ribofuranose-1-acetate-2,3,5-tribenzoate) afforded the new ribofuranosides. These compounds were evaluated for their antioxidant and antimicrobial activities (using broth microdilution method). The structural assignments of the synthesized compounds were made on the basis of elemental analyses and spectroscopic data.     

Reuse Of Pacemakers In Ghana And Nigeria: Medical,Legal, Cultural And Ethical Perspectives

According to the World Health Organization (WHO) cardiovascular disease (CVD) is the leading cause of death globally. Over 80% of CVD deaths take place in low‐ and middle‐income countries (LMICs). It is estimated that 1 million to 2 million people worldwide die each year due to lack of access to an implantable cardiac defibrillator (ICD) or a pacemaker. Despite the medical, legal, cultural and ethical controversies surrounding the pacemaker reutilization, studies done so far on the reuse of postmortem pacemakers show it to be safe and effective with an infection rate of 1.97% and device malfunction rate of 0.68%. Pacemaker reutilization can be effectively and safely done and does not pose significant additional risk to the recipient. Heart patients with reused pacemakers have an improved quality of life compared to those without pacemakers. The thesis of this paper is that pacemaker reutilization is a life‐saving initiative in LMICs of Nigeria and Ghana. It is cost effective; consistent with the principles of beneficence, nonmaleficence, and justice with a commitment to stewardship of resources and the Common Good. Used pacemakers with adequate battery life can be properly sterilized for use by patients in LMICs who cannot afford the cost of a new pacemaker.     

Immunochemical Identification Of α-Amylass In Developing, Mature And Germinated Triticale Seeds

Extracts from triticale (Triticale hexaploide Lart.) cultivar 6A190 kernels harvested at 10 days post anthesis (developing), 41 days post anthesis (mature) and after 7 days' germination, were analyzed for their α-amylase isoenzymic composition by electro-phoretic and immunochemical techniques. One antigenic α-amylase (I) was common to both developing and germinated seeds but was present in greater quantity during germination. A second antigenic cr-amylase (II) was found in germinated seeds only and was barely detectable, even in an inactive state, in developing seeds. A third antigenic α-amylase (III) was found only in developing seeds. In mature seeds the α-amylase (II) predominated. α-Amylase (I) was also present but to a lesser extent than that found in developing seeds. It was concluded that the abnormally high levels of a amylase found in triticale 6A190 in the mature, non-sprouted kernel arose due to a lack of dormancy in the grain, resulting in the de novo synthesis of α-amylase (II).     

Clearing, Cuticle Removal, And Staining For The Fertile Bracts (Lemmas And Paleas) Of Grass Anthoecia

The epidermis of the bracts enclosing the flower of grasses contains epidermal cell patterns which are indicative of phylogenetic and systematic relationships among taxa. Treating the heavily cutinized anthoecial bracts (fertile lemma and palea) with 10% NaOH results in the removal of sufficient cuticle to allow examination of the cells of the epidermis. After clearing and removal of the cuticle, the bracts are bleached, washed, dehydrated, and if studied by light microscopy, stained in 2 % chlorazol black E and mounted in Diaphane; or, if studied by scanning electron microscopy, dried by the critical-point method and either left uncoated or coated with a film of various conductive metals.     

The West Gondwanan Occurrence Of The Hybodontid Shark Priohybodus, And The Late Jurassic–Early Cretaceous Age Of The Tacuarembó Formation, Uruguay

Priohybodus cf. P. arambourgi is reported for the first time from the Tacuarembó Formation of Uruguay. This species is a hybodontid shark known previously only from Upper Jurassic and Lower Cretaceous deposits of Saharan Africa and the Arabian Peninsula. The material (22 isolated teeth and a dorsal fin spine) was found in a thin bone bed, associated with abundant bone fragments, scales and teeth of semionotiform fishes and theropod dinosaurs. Until now, the age of the Tacuarembó Formation has been difficult to determine because its fossil content lacked useful biostratigraphic indicators. The finding of Priohybodus cf. P. arambourgi in that unit greatly expands the palaeobiogeographic range of the species, and allows us to propose a Late Jurassic–Early Cretaceous age for the Tacuarembó Formation.