86 research outputs found

    Jablotron 100-Based Corporation Access System

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    Bakalářská práce se zabývá problematikou návrhu a realizace přístupového systému podniku s elektronickým zabezpečovacím systémem Jablotron 100 a jeho propojením s jinými systémy. Byl navržen a naprogramován můstek s API rozhraním pro ovládání systému Jablotron 100. Tento můstek byl použit pro realizaci webového uživatelského rozhraní k ovládání přístupového systému. Dále byl vytvořen koncept získávání dat docházky ze systému Jablotron 100.This bachelor thesis deals with the design and implementation of an enterprise access control system based on the electronic security system Jablotron 100 and its connection with external systems. The bridge with an API interface for controlling the Jablotron 100-based corporation access system has been designed and programmed. This bridge was used to implement the web user interface to control the access system. Furthermore, the concept of collecting attendance data from the Jablotron 100-based system was created.

    Adaptive Algorithm for Multi-armed Bandit Problem with High-dimensional Covariates

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    This paper studies an important sequential decision making problem known as the multi-armed stochastic bandit problem with covariates. Under a linear bandit framework with high-dimensional covariates, we propose a general multi-stage arm allocation algorithm that integrates both arm elimination and randomized assignment strategies. By employing a class of high-dimensional regression methods for coefficient estimation, the proposed algorithm is shown to have near optimal finite-time regret performance under a new study scope that requires neither a margin condition nor a reward gap condition for competitive arms. Based on the synergistically verified benefit of the margin, our algorithm exhibits adaptive performance that automatically adapts to the margin and gap conditions, and attains optimal regret rates simultaneously for both study scopes, without or with the margin, up to a logarithmic factor. Besides the desirable regret performance, the proposed algorithm simultaneously generates useful coefficient estimation output for competitive arms and is shown to achieve both estimation consistency and variable selection consistency. Promising empirical performance is demonstrated through extensive simulation and two real data evaluation examples.</p

    Biocatalytic Formal Anti-Markovnikov Hydroamination and Hydration of Aryl Alkenes

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    Biocatalytic anti-Markovnikov alkene hydroamination and hydration were achieved based on two concepts involving enzyme cascades: epoxidation–isomerization–amination for hydroamination and epoxidation–isomerization–reduction for hydration. An <i>Escherichia coli</i> strain coexpressing styrene monooxygenase (SMO), styrene oxide isomerase (SOI), ω-transaminase (CvTA), and alanine dehydrogenase (AlaDH) catalyzed the hydroamination of 12 aryl alkenes to give the corresponding valuable terminal amines in high conversion (many ≥86%) and exclusive anti-Markovnikov selectivity (>99:1). Another <i>E. coli</i> strain coexpressing SMO, SOI, and phenylacetaldehyde reductase (PAR) catalyzed the hydration of 12 aryl alkenes to the corresponding useful terminal alcohols in high conversion (many ≥80%) and very high anti-Markovnikov selectivity (>99:1). Importantly, SOI was discovered for stereoselective isomerization of a chiral epoxide to a chiral aldehyde, providing some insights on enzymatic epoxide rearrangement. Harnessing this stereoselective rearrangement, highly enantioselective anti-Markovnikov hydroamination and hydration were demonstrated to convert α-methylstyrene to the corresponding (<i>S</i>)-amine and (<i>S</i>)-alcohol in 84–81% conversion with 97–92% <i>ee</i>, respectively. The biocatalytic anti-Markovnikov hydroamination and hydration of alkenes, utilizing cheap and nontoxic chemicals (O<sub>2</sub>, NH<sub>3</sub>, and glucose) and cells, provide an environmentally friendly, highly selective, and high-yielding synthesis of terminal amines and alcohols

    Enantioselective Alkyne Conjugate Addition Enabled by Readily Tuned Atropisomeric <i>P</i>,<i>N</i>‑Ligands

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    By the nature of its structure, the 5-membered chiral biaryl heterocyclic scaffold represents a departure from 6-membered <i>P</i>,<i>N</i>-ligands that facilitates tuning and enables ligand evolution to address issues of selectivity and reactivity. In this vein, the Cu-catalyzed enantioselective conjugate alkynylation of Meldrum’s acid acceptors is reported using Me-StackPhos. Enabled by this new ligand, the reaction tolerates a wide range of alkynes furnishing the products in high yields and excellent enantioselectivity. The transformation provides access to highly useful chiral β-alkynyl Meldrum’s acid building blocks as demonstrated by an efficient enantioselective synthesis of the preclinical agent OPC 51803

    Thioketal-Based Electrochemical Sensor Reveals Biphasic Effects of l‑DOPA on Neuroinflammation

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    Neuroinflammation is linked closely to neurodegenerative diseases, with reactive oxygen species (ROS) exacerbating neuronal damage. Traditional electrochemical sensors show promise in targeting cellular ROS to understand their role in neuropathogenesis and assess therapies. Nevertheless, these sensors face challenges in mitigating the ROS oxidation overpotential. We herein introduce an ROS oxidation-independent nucleic acid sensor for in situ ROS analysis and therapeutic assessment. The sensor comprises ionizable and thioketal (TK)-based lipids with methylene blue-tagged nucleic acids on a glass carbon electrode. ROS exposure triggers cleavage within the sensor’s thioketal moiety, detaching the nucleic acid from the electrode and yielding quantifiable results via square-wave voltammetry. Importantly, the sensor’s low potential window minimizes interference, ensuring precise ROS measurements with high selectivity. Using this sensor, we unveil levodopa’s dose-dependent biphasic effect on neuroinflammation: low doses alleviate oxidative stress, while high doses exacerbate it. The TK-based sensor offers a promising methodology for investigating neuroinflammation’s pathogenesis and screening potential treatments, advancing neurodegenerative disease research

    Catalytic Dehydrative Lactonization of Allylic Alcohols

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    A convenient strategy for the synthesis of phthalides and γ-butyrolactones is reported. The method utilizes readily prepared allylic alcohols in formal Au­(I)- and Pd­(II)-catalyzed S<sub>N</sub>2′ reactions. Using these catalysts, exclusive formation of the desired five-membered lactones is observed, completely avoiding the competing direct lactonization pathway that forms the undesired seven-membered ring with protic acids and alternative metal salts. This mild and operationally simple method notably tolerates exomethylene groups and should find use in both phthalide and terpene syntheses

    Histological assessment of cartilage restoring effects of the three groups.

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    <p>The left two columns were H&E stained and the right two columns with Safranin-O. For each staining, the images of the right column are magnified from the left column. The capillary infiltration areas were indicated with black arrows. All scale bars represent 200 µm.</p

    Oxidative Degradation of Thermosets Based on Thioketal Cleavable Linkages in Aqueous Environment

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    Thermosets are rigid, infusible, and unmolded materials containing three-dimensional (3D) cross-linked structures. They are considered a fundamental pillar in the international economy, which are produced by 65 million tons annually. The responsive cross-linking moieties provide the thermosets characterized with outstanding physicochemical properties such as stiffness, degradability, and chemical and thermal resistance. We prepared degradable thermoset materials using thioketal (TK) cross-linkers, which underwent main-chain or side change degradation in the presence of hydrogen peroxide in water. TK cross-linkers at different concentrations (5, 10, and 20% wt %) were polymerized with 2-hydroxyethyl acrylate (HEA) or with 2-hydroxyethyl methacrylate (HEMA) and 1-vinyl-2-pyrrolidone (PD) to produce cross-linked poly(HEA) and poly(HEMA-PD) by free radical polymerization, respectively. The resultant polymer materials completely degraded in hydrogen peroxide/water (3–30%, vol). Using isophorone diisocyanate, we also produced degradable polyurethane based on TK-bearing diol. We prepared a 3D degradable thermoset using the Direct-Ink-Writing (DIW) 3D printing technology, which was charged by diethylene glycol diacrylate (15%, wt %) and a prepolymer (isophorone diisocyanate terminated by acrylate moieties) containing diol-thioketal linkage (15%, wt %). Finally, we found that TK-poly(HEA) underwent microbial degradation by Lactobacillus jensenii at 37 °C, which indicates a benign eco-friendly effect
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