Core–Shell Metal–Ceramic Microstructures: Mechanism of Hydrothermal Formation and Properties as Catalyst Materials

Unique metal–ceramic composites with core–shell microarchitecture (γ-Al₂O₃@Al and spinel-MeAl₂O₄@Al, Me = Zn, Ni, Co, Mn, and Mg) were obtained by a simple hydrothermal surface oxidation (HTSO) of Al metal particles in an aqueous solution of heterometal ions at elevated temperatures (393–473 K). The reactions afforded self-constructed core–shell microarchitecture with Al core encapsulated by the high-surface-area γ-Al₂O₃ or spinel metal aluminates (MeAl₂O₄) shell with various surface morphologies, compositions, and excellent physicochemical properties. Extensive experimental and theoretical investigation with period 3–6 metal elements (Na⁺, Ca²⁺, Sr²⁺, Ba²⁺, K⁺, Fe³⁺, Cu²⁺, Zn²⁺, Ni²⁺, Co²⁺, Mn²⁺, and Mg²⁺) at various metal concentrations and temperatures revealed that the heterogeneous self-construction of spinel-MeAl₂O₄@Al primarily depends on two intrinsic properties of the additive metal ions: (i) thermodynamic stability constant of the metal hydroxide complex and (ii) size of the metal ion. The spinel-MeAl₂O₄@Al microstructures formed with a limited number of hetero metal ions (Me = Zn²⁺, Ni²⁺, Co²⁺, Mn²⁺, and Mg²⁺) with (i) moderate rates of the hydroxide formation with compatible kinetics to the hydrolysis of aluminum on the Al surface and (ii) small size of additive metal ions enough for diffusion through the shell layer. As heterogeneous catalyst substrates, these metal–ceramic composites delivered markedly enhanced catalytic performance at intensive reaction conditions because of their facile heat transfer and superior physicochemical surface properties. The performance and effects of the core–shell metal–ceramic composites were demonstrated using Rh catalysts supported on MgAl₂O₄@Al. The Rh/MgAl₂O₄@Al catalyst was utilized for the endothermic glycerol stream reforming (C₃H₈O₃ + 3H₂O ⇄ 3CO₂ + 7H₂, Δ<i>H</i>₀²⁹⁸ = 128 kJ mol^–1), exhibiting markedly greater catalytic performance than the conventional Rh/MgAl₂O₄ under intensive reaction conditions attributed to significantly facilitated heat transport through the core–shell metal–ceramic microstructures

Clinical characteristics and treatment outcomes of <i>Clostridium difficile</i> infections with ribotypes 017 (R017) and 018 (R018)

<p>Clinical characteristics and treatment outcomes of <i>Clostridium difficile</i> infections with ribotypes 017 (R017) and 018 (R018)</p

Factors related to 30-day mortality among <i>Clostridium difficile</i> patients in a final multiple logistic regression model, 2009–2012

<p>Factors related to 30-day mortality among <i>Clostridium difficile</i> patients in a final multiple logistic regression model, 2009–2012</p

Zeolitic Imidazolate Framework Membrane with Marked Thermochemical Stability for High-Temperature Catalytic Processes

The thermochemical stability of metal organic framework (MOF) membranes is vital for the application in chemical-reaction and -separation processes, but understanding the stability of MOF membranes and structure–property relationships under antagonistic chemical atmosphere is still required. In this work, a supported zeolitic imidazolate framework (ZIF) membrane, ZIF-7/MgO-Al₂O₃, of unprecedented hydrothermal stability is obtained by a modulation of the acid–base chemistry at the membrane/support interface. The solid/solid interface acidity that has been overlooked in the fields turns out to have paramount inducing effects on the thermochemical stability of ZIF membranes, resulting in the catastrophic acid-catalyzed decomposition of ZIF frameworks at atomic level. The ZIF-7/MgO-Al₂O₃ of marked thermochemical stability permits the first significant application of MOF membranes for catalytic membrane reactor (MR) in severe and practical process conditions, performing water–gas shift reaction (CO + H₂O ↔ CO₂ + H₂) at considerably high temperatures (473–673 K) and steam concentrations (20–40%). The findings and results provide significant new insights on the property and stability of ZIF membranes with extensive opportunities for thermochemical processes that have been permitted only for the inorganic membranes such as zeolites, palladium, and metal oxides

Additional file 1: of A few antibiotics can represent the total hospital antibiotic consumption

Supplementary materials. The model for ordinary least squares (OLS) estimator. (DOCX 97 kb

Cost-Effective Scalable Synthesis of Mesoporous Germanium Particles <i>via</i> a Redox-Transmetalation Reaction for High-Performance Energy Storage Devices

Nanostructured germanium is a promising material for high-performance energy storage devices. However, synthesizing it in a cost-effective and simple manner on a large scale remains a significant challenge. Herein, we report a redox-transmetalation reaction-based route for the large-scale synthesis of mesoporous germanium particles from germanium oxide at temperatures of 420–600 °C. We could confirm that a unique redox-transmetalation reaction occurs between Zn⁰ and Ge⁴⁺ at approximately 420 °C using temperature-dependent <i>in situ</i> X-ray absorption fine structure analysis. This reaction has several advantages, which include (i) the successful synthesis of germanium particles at a low temperature (∼450 °C), (ii) the accommodation of large volume changes, owing to the mesoporous structure of the germanium particles, and (iii) the ability to synthesize the particles in a cost-effective and scalable manner, as inexpensive metal oxides are used as the starting materials. The optimized mesoporous germanium anode exhibits a reversible capacity of ∼1400 mA h g^–1 after 300 cycles at a rate of 0.5 C (corresponding to the capacity retention of 99.5%), as well as stable cycling in a full cell containing a LiCoO₂ cathode with a high energy density (charge capacity = 286.62 mA h cm^–3)

Potential Role of Hedgehog Pathway in Liver Response to Radiation

<div><p>Radiation-induced fibrosis constitutes a major problem that is commonly observed in the patients undergoing radiotherapy; therefore, understanding its pathophysiological mechanism is important. The Hedgehog (Hh) pathway induces the proliferation of progenitors and myofibroblastic hepatic stellate cells (MF-HSCs) and promotes the epithelial-to-mesenchymal transition (EMT), thereby regulating the repair response in the damaged liver. We examined the response of normal liver to radiation injury. Male mice were sacrificed at 6 weeks and 10 weeks after exposure to a single dose of 6 Gy and the livers were collected for biochemical analysis. Irradiated (IR) and control mice were compared for progenitors, fibrosis, Hh pathway, and EMT at 6 and 10 weeks post irradiation. Fatty hepatocytes were observed and the expressions of Hh ligand, Indian Hh. were greater in the livers at 6 weeks, whereas expression of another Hh ligand, Sonic Hh, increased at 10 weeks post irradiation. Both Smoothened, Hh receptor, and Gli2, Hh-target gene, were up-regulated at 6 and 10 weeks after irradiation. Accumulation of progenitors (CD44, Pan-cytokeratin, and Sox9) was significant in IR livers at 6 and 10 weeks. RNA analysis showed enhanced expression of the EMT–stimulating factor, tgf-β, in the IR livers at 6 weeks and the upregulation of mesenchymal markers (α-SMA, collagen, N-cadherin, and s100a4), but down-regulation of EMT inhibitors, in IR mouse livers at 6 and 10 weeks. Increased fibrosis was observed in IR mouse livers at 10 weeks. Treatment of mice with Hh inhibitor, GDC-0449, suppressed Hh activity and block the proliferation of hepatic progenitor and expression of EMT-stimulating genes in irradiated mice. Therefore, those results demonstrated that the Hh pathway increased in response to liver injury by radiation and promoted a compensatory proliferation of MF-HSCs and progenitors, thereby regulating liver remodeling.</p></div

Classification accuracies for seven-sound category classifiers built for each subject separately using MSVM-RFE.

<p>Error bars represent one standard deviation of the mean accuracy.</p

Classification accuracies across subjects for all seven sound categories using MSVM-RFE.

<p>Based on within-subject analysis results, the data from subject 4 was not included for the across-subject analysis. “leave sub1 out” means leaving subject 1 out. That means the model is trained on data from the 2nd, 3rd, 5th, and 6th subjects and is tested on data from the 1st subject.</p

Stimulus categories and the quality score (QS) of sound exemplars averaged within each category.

<p>Stimulus categories and the quality score (QS) of sound exemplars averaged within each category.</p