bluuebunny/crossref_metadata_2025 huggingface dataset:
Extremum seeking for optimal control problems with unknown time‐varying systems and unknown objective functions
Authors: Scheinker Alexander , Scheinker David
Published: February 2020

We consider the problem of optimal feedback control of an unknown, noisy, time‐varying, dynamic system that is initialized repeatedly. Examples include a robotic manipulator which must perform the same motion, such as assisting a human, repeatedly and accelerating cavities in particle accelerators which are turned on for a fraction of a second with given initial conditions and vary slowly due to temperature fluctuations. We present an approach that applies to systems of practical interest. The method presented here is model independent; does not require knowledge of the objective function; is robust to measurement noise; is applicable for any set of initial conditions; is applicable to simultaneously controlling an arbitrary number of parameters; and may be implemented with a broad range of continuous or discontinuous functions such as sine or square waves. For systems with convex cost functions we prove that our algorithm will produce controllers that approach the minimal cost. For linear systems we reproduce the cost minimizing linear quadratic regulator optimal controller that could have been designed analytically had the system and cost function been known. We demonstrate the effectiveness of the algorithm with simulation studies of noisy and time‐varying systems.
Synergistically Tuning Electronic Structure of Porous β‐Mo2C Spheres by Co Doping and Mo‐Vacancies Defect Engineering for Optimizing Hydrogen Evolution Reaction Activity
Authors: Ma Yufei , Chen Meng , Geng Hongbo , Dong Huafeng , Wu Ping , Li Xiumin , Guan Guoqing , Wang Tiejun
Published: February 2020

The development of novel non‐noble electrocatalysts with controlled structure and surface composition is critical for efficient electrochemical hydrogen evolution reaction (HER). Herein, the rational design of porous molybdenum carbide (β‐Mo2C) spheres with different surface engineered structures (Co doping, Mo vacancies generation, and coexistence of Co doping and Mo vacancies) is performed to enhance the HER performance over the β‐Mo2C‐based catalyst surface. Density functional theory calculations and experimental results reveal that the synergistic effect of Co doping with Mo vacancies increases the electron density around the Fermi‐level and modulates the d band center of β‐Mo2C so that the strength of the MoH bond is reasonably optimized, thus leading to an enhanced HER kinetics. As expected, the optimized Co50‐Mo2C‐12 with porous structure displays a low overpotential (η10 = 125 mV), low‐onset overpotential (ηonset = 27 mV), and high exchange current density (j0 = 0.178 mA cm−2). Furthermore, this strategy is also successfully extended to develop other effective metal (e.g., Fe and Ni) doped β‐Mo2C electrocatalyst, indicating that it is a universal strategy for the rational design of highly efficient metal carbide‐based HER catalysts and beyond.
An NIR‐Responsive DNA‐Mediated Nanotetrahedron Enhances the Clearance of Senescent Cells
Authors: Qu Aihua , Wu Xiaoling , Li Si , Sun Maozhong , Xu Liguang , Kuang Hua , Xu Chuanlai
Published: February 2020

Senescence is a state of stable cell cycle arrest that can escape apoptosis and lead to aging and numerous age‐related diseases. In this study, an upconversion‐nanoparticle (UCNP)‐centered Au20–Au30 nanoparticles tetrahedron (UAuTe) is prepared by DNA hybridization, which can selectively accelerate the clearance of senescent cells. When the beta‐2‐microglobulin antibody (anti‐B2MG) on the Au NPs recognizes senescent cells, the application of near‐infrared (NIR) light induces the disassembly of the UAuTe by breaking the boronic ester linkage. Subsequently, the Granzyme B exposed on the UCNPs induces apoptosis in senescent cells, which can then be tracked by changes in fluorescence. It is found that, as compared to single Granzyme B, the UAuTe can not only control the Granzyme B delivery by NIR‐responsivity, but also synergistically target and activate the Granzyme B in the senescent cell without the need of perforin. Moreover, this tool is applied successfully in vivo; the results demonstrate that the NIR‐responsive tetrahedron can restore renal function, tissue homeostasis, fur density, and athletic ability in a mouse model of senescence after 30 d of treatment. The NIR‐induced tetrahedron provides a practical strategy for clinical diagnosis and therapy, particularly for aging and age‐related diseases.
Modular and Customized Fabrication of 3D Functional Microgels for Bottom‐Up Tissue Engineering and Drug Screening
Authors: Yang Wenguang , Cai Shuxiang , Chen Yibao , Liang Wenfeng , Lai Youbin , Yu Haibo , Wang Yuechao , Liu Lianqing
Published: February 2020

Customized generation of 3D functional building blocks is crucial for bottom‐up tissue engineering. Currently, high throughput production, high survival rates, and well‐controlled shapes are considered as three major challenges in fabricating microgels. Here, an optofluidic maskless lithography system that combines digital micromirror device based 3D printing and microfluidic technologies for fabricating 3D functional microgels, is presented. With this system, 3D microgels can be custom designed online and manufactured modularly in a microfluidic device. The fabrication process is based on shadowed light, highly flexible, and requires no physical masks. Furthermore, cells in microgels exhibit features that are more similar to the complex in vivo conditions, including morphology, proliferation, and drug resistance.
Use of biosolids for sod production: Impact on the import/export of nutrients, heavy metals, and soil mineral matter
Authors: Griffith Shane , Bero Nicholas , Stier John , Obear Glen , Ruis Sabrina J. , Soldat Douglas
Published: February 2020

Sod production has been criticized as being unsustainable because of the soil export that occurs at each harvest. Wastewater treatment residuals (biosolids) disposal is often limited by nutrient or metal accumulation in the soil. Biosolids‐based sod production may be a solution to minimize soil loss and land‐apply wastewater residuals. The objectives of this study were to assess biosolids‐based sod production impact on import and export of nutrients, heavy metals, carbon, and to quantify soil loss from sod harvest with and without biosolids. Anaerobically digested, dewatered sludge (Cake) and Cake mixed with sand and sawdust (MetroMix) were applied at three rates based on estimated plant available nitrogen (PAN). An additional treatment mimicked conventional sod production practices that rely on synthetic fertilizer. All biosolids rates and sources increased Mehlich‐3 extractable phosphorus (P) to > 175 mg kg−1 in the harvested sod, which could contribute to P runoff or leaching at the site of establishment. Heavy metal concentrations from both biosolids sources were below EPA loading limits and would require over 200 years of regular application (22 Mg ha−1) to exceed EPA maximum cumulative loading limits. Biosolids at 22 Mg ha−1 did little to reduce soil mineral matter loss compared to conventionally grown sod. After two sod production cycles, soil carbon increased by 50% in the surface soil (0–10 cm), but was reduced at a depth of 20–30 cm. While high P concentrations in the biosolids limit repeated applications, moderate use of biosolids may alleviate reliance on synthetic fertilizers for N and P.
Water Catalysis of the Reaction of Methanol with OH Radical in the Atmosphere is Negligible
Authors: Wu Junjun , Gao Lu Gem , Varga Zoltan , Xu Xuefei , Ren Wei , Truhlar Donald G.
Published: February 2020

Faced with the contradictory results of two recent experimental studies [Jara‐Toro et al., Angew. Chem. Int. Ed. 2017, 56, 2166 and Chao et al., Angew. Chem. Int. Ed. 2019, 58, 5013] of the possible catalytic effect of water vapor on CH3OH + OH reaction, we report calculations that corroborate the conclusion made by Chao et al. and extend the rate constant evaluation down to 200 K. The rate constants of the CH3OH + OH reaction catalyzed by a water molecule are computed as functions of temperature and relative humidity using high‐level electronic structure and kinetics calculations. The Wuhan–Minnesota Scaling (WMS) method is used to provide accurate energetics to benchmark a density functional for direct dynamics. Both high‐frequency and low‐frequency anharmonicities are included. Variational and tunneling effects are treated by canonical variational transition state theory with multidimensional small‐curvature tunneling. And, most significantly, we include multistructural effects in the rate constant calculations. Our calculations show that the catalytic effect of water vapor is not observable at 200–400 K.
Active Electron Density Modulation of Co3O4‐Based Catalysts Enhances their Oxygen Evolution Performance
Authors: He Dong , Song Xianyin , Li Wenqing , Tang Chongyang , Liu Jiangchao , Ke Zunjian , Jiang Changzhong , Xiao Xiangheng
Published: February 2020

Despite the fact that many strategies have been developed to improve the efficiency of the oxygen evolution reaction (OER), the precise modulation of the surface electronic properties of catalysts to improve their catalytic activity is still challenging. Herein, we demonstrate that the surface active electron density of Co3O4 can be effectively regulated by an argon‐ion irradiation method. X‐ray photoelectron and synchrotron x‐ray absorption spectroscopy, UV photoelectron spectrometry, and DFT calculations show that the surface active electron density band center of Co3O4 has been upshifted, leading to a significantly enhanced absorption capability of the oxo group. The optimized Co3O4‐based catalysts exhibit an excellent overpotential of 260 mV at 10 mA cm−2 and Tafel slope of 54 mV dec−1, superior to the capability of the benchmark RuO2, representing one of the best Co‐based OER catalysts. This approach could guide the future rational design and discovery of ideal electrocatalysts.
Purifying stem cell‐derived red blood cells: a high‐throughput label‐free downstream processing strategy based on microfluidic spiral inertial separation and membrane filtration
Authors: Guzniczak Ewa , Otto Oliver , Whyte Graeme , Chandra Tamir , Robertson Neil A. , Willoughby Nik , Jimenez Melanie , Bridle Helen
Published: February 2020

Cell‐based therapeutics, such as in vitro manufactured red blood cells (mRBCs), are different to traditional biopharmaceutical products (the final product being the cells themselves as opposed to biological molecules such as proteins) and that presents a challenge of developing new robust and economically feasible manufacturing processes, especially for sample purification. Current purification technologies have limited throughput, rely on expensive fluorescent or magnetic immunolabeling with a significant (up to 70%) cell loss and quality impairment. To address this challenge, previously characterized mechanical properties of umbilical cord blood CD34+ cells undergoing in vitro erythropoiesis were used to develop an mRBC purification strategy. The approach consists of two main stages: (a) a microfluidic separation using inertial focusing for deformability‐based sorting of enucleated cells (mRBC) from nuclei and nucleated cells resulting in 70% purity and (b) membrane filtration to enhance the purity to 99%. Herein, we propose a new route for high‐throughput (processing millions of cells/min and mls of medium/min) purification process for mRBC, leading to high mRBC purity while maintaining cell integrity and no alterations in their global gene expression profile. Further adaption of this separation approach offers a potential route for processing of a wide range of cellular products.
Simultaneous quantification of candesartan and irbesartan in rabbit eye tissues by liquid chromatography–tandem mass spectrometry
Authors: Tan Aimin , Gui Xuan , Wong Molly , Deng Hui , Gu Guifen , Fanaras Constantine , Fanaras John C.
Published: February 2020

Diabetic retinopathy is a major cause of vision loss in adults. Novel eye‐drop formulations of candesartan and irbesartan are being developed for its cure or treatment. To support a preclinical trial in rabbits, it was critical to develop and validate a new LC–MS/MS method for simultaneous quantification of candesartan and irbesartan in rabbit eye tissues (cornea, aqueous humor, vitreous body and retina/choroid). Eye tissue samples were first homogenized in H2O‐diluted rabbit plasma. The candesartan and irbesartan in the supernatants together with their respective internal standards (candesartan‐d4 and irbesartan‐d4) were extracted by solid‐phase extraction. The extracted samples were injected onto a C18 column for gradient separation. The MS detection was in the positive electrospray ionization mode using the multiple reaction monitoring transitions of m/z 441 → 263, 445 → 267, 429 → 207, and 433 → 211 for candesartan, candesartan‐d4, irbesartan and irbesartan‐d4, respectively. For the validated concentration ranges (2–2000 and 5–5000 ng/g for candesartan and irbesartan, respectively), the within‐run and between‐run accuracies (% bias) were within the range of −8.0–10.0. The percentage CV ranged from 0.6 to 7.3. There was no significant matrix interference nor matrix effect from different eye tissues and different rabbits. The validated method was successfully used in the Good Laboratory Practice (GLP) study of rabbits.
Electrocatalytic Oxidation of Hydroxide Ions by Co3O4 and Co3O4@SiO2 Nanoparticles Both at Particle Ensembles and at the Single Particle Level
Authors: Xie Ruo‐Chen , Volokhova Maria , Boldin Aleksei , Seinberg Liis , Tsujimoto Masahiko , Yang Minjun , Rasche Bertold , Compton Richard G.
Published: February 2020

We report that the Co3O4 nanoparticle‐mediated electrochemical oxidation under alkaline conditions of the hydroxide ion on a glassy carbon macroelectrode leads to hydrogen peroxide as the initial oxidation product of electron transfer. The latter is inferred to subsequently partially decompose to dioxygen by catalytic chemical reaction at the nanoparticles. At the single particle level, electrochemical particle‐electrode impacts point out the rate‐determining step and the limiting kinetics of the reaction. Furthermore, particles with a core‐shell structure of a Co3O4 core and SiO2 shell are synthesised, and their electrochemical behaviour is studied and compared with bare Co3O4 nanoparticles, suggesting the very likely broken or highly porous state of the silica shell, which is not otherwise easily distinguished, for example, by electron microscopy.
Study on the effect of sample shapes on the thermal shock behavior of ZrB2‐SiC‐Graphite sharp leading edge
Authors: Wang Anzhe , Liao Hailong , Zhang Tao , Jiang Minqi , Guo Fuxiao , Wang Yongzheng
Published: February 2020

Reliable evaluation of the thermal shock behavior of sharp leading edges (SLEs) was hampered by a lack of available experimental method in past decades. Herein, a novel water spraying method was utilized to investigate the shape effect of ZrB2‐SiC‐Graphite SLEs during thermal shock. Experimental results indicated that the critical failure temperature of ZrB2‐SiC‐Graphite SLEs was most sensitive to the wedge angle, which could lead to a dramatic attenuation by about 35% from 12° to 9°, and was relatively little affected by the tip radius of curvature and the thickness. Simulation results further revealed that the decay of critical failure temperature was mainly due to the significant stress concentration caused by the reduction of wedge angle. Scanning electron microscopy observation proved that cracks tend to bypass graphite flakes due to their weak interfacial bonding, while branching always occurred when encountering hard phases or inclusions.
Controlled Covalent Functionalization of 2 H‐MoS2 with Molecular or Polymeric Adlayers
Authors: Quirós‐Ovies Ramiro , Vázquez Sulleiro Manuel , Vera‐Hidalgo Mariano , Prieto Javier , Gómez I. Jénnifer , Sebastián Víctor , Santamaría Jesús , Pérez Emilio M.
Published: February 2020

Most air‐stable 2D materials are relatively inert, which makes their chemical modification difficult. In particular, in the case of MoS2, the semiconducting 2 H‐MoS2 is much less reactive than its metallic counterpart, 1T‐MoS2. As a consequence, there are hardly any reliable methods for the covalent modification of 2 H‐MoS2. An ideal method for the chemical functionalization of such materials should be both mild, not requiring the introduction of a large number of defects, and versatile, allowing for the decoration with as many different functional groups as possible. Herein, a comprehensive study on the covalent functionalization of 2 H‐MoS2 with maleimides is presented. The use of a base (Et3N) leads to the in situ formation of a succinimide polymer layer, covalently connected to MoS2. In contrast, in the absence of base, functionalization stops at the molecular level. Moreover, the functionalization protocol is mild (occurs at room temperature), fast (nearly complete in 1 h), and very flexible (11 different solvents and 10 different maleimides tested). In practical terms, the procedures described here allow for the chemist to manipulate 2 H‐MoS2 in a very flexible way, decorating it with polymers or molecules, and with a wide range of functional groups for subsequent modification. Conceptually, the spurious formation of an organic polymer might be general to other methods of functionalization of 2D materials, where a large excess of molecular reagents is typically used.
Dual Inhibition of Pyruvate Dehydrogenase Complex and Respiratory Chain Complex Induces Apoptosis by a Mitochondria‐Targeted Fluorescent Organic Arsenical in vitro and in vivo
Authors: Liu Yu‐Jiao , Fan Xiao‐Yang , Zhang Dong‐Dong , Xia Yin‐Zheng , Hu Yan‐Jun , Jiang Feng‐Lei , Zhou Fu‐Ling , Liu Yi
Published: February 2020

Based on the potential therapeutic value in targeting mitochondria and the fluorophore tracing ability, a fluorescent mitochondria‐targeted organic arsenical PDT‐PAO‐F16 was fabricated, which not only visualized the cellular distribution, but also exerted anti‐cancer activity in vitro and in vivo via targeting pyruvate dehydrogenase complex (PDHC) and respiratory chain complexes in mitochondria. In details, PDT‐PAO‐F16 mainly accumulated into mitochondria within hours and suppressed the activity of PDHC resulting in the inhibition of ATP synthesis and thermogenesis disorder. Moreover, the suppression of respiratory chain complex I and IV accelerated the mitochondrial dysfunction leading to caspase family‐dependent apoptosis. In vivo, the acute promyelocytic leukemia was greatly alleviated in the PDT‐PAO‐F16 treated group in APL mice model. Our results demonstrated the organic arsenical precursor with fluorescence imaging and target‐anticancer efficacy is a promising anticancer drug.
Sharp Extinction Rates for Fast Diffusion Equations on Generic Bounded Domains
Authors: Bonforte Matteo , Figalli Alessio
Published: February 2020

We investigate the homogeneous Dirichlet problem for the fast diffusion equation ut = Δum, posed in a smooth bounded domain Ω ⊂ ℝN, in the exponent range ms = (N − 2)+/(N + 2) < m < 1. It is known that bounded positive solutions extinguish in a finite time T > 0, and also that they approach a separate variable solution u(t, x) ∼ (T − t)1/(1 − m)S(x) as t → T−, where S belongs to the set of solutions to a suitable elliptic problem and depends on the initial datum u0. It has been shown recently that v(x, t) = u(t, x) (T − t)−1/(1 − m) tends to S(x) as t → T−, uniformly in the relative error norm. Starting from this result, we investigate the fine asymptotic behavior and prove sharp rates of convergence for the relative error. The proof is based on an entropy method relying on an (improved) weighted Poincaré inequality, which we show to be true on generic bounded domains. Another essential aspect of the method is the new concept of “almost‐orthogonality,” which can be thought of as a nonlinear analogue of the classical orthogonality condition needed to obtain improved Poincaré inequalities and sharp convergence rates for linear flows. © 2019 Wiley Periodicals, Inc.
Computation of Electromagnetic Properties of Molecular Ensembles
Authors: Fernandez‐Corbaton Ivan , Beutel Dominik , Rockstuhl Carsten , Pausch Ansgar , Klopper Wim
Published: February 2020

We outline a methodology for efficiently computing the electromagnetic response of molecular ensembles. The methodology is based on the link that we establish between quantum‐chemical simulations and the transfer matrix (T‐matrix) approach, a common tool in physics and engineering. We exemplify and analyze the accuracy of the methodology by using the time‐dependent Hartree‐Fock theory simulation data of a single chiral molecule to compute the T‐matrix of a cross‐like arrangement of four copies of the molecule, and then computing the circular dichroism of the cross. The results are in very good agreement with full quantum‐mechanical calculations on the cross. Importantly, the choice of computing circular dichroism is arbitrary: Any kind of electromagnetic response of an object can be computed from its T‐matrix. We also show, by means of another example, how the methodology can be used to predict experimental measurements on a molecular material of macroscopic dimensions. This is possible because, once the T‐matrices of the individual components of an ensemble are known, the electromagnetic response of the ensemble can be efficiently computed. This holds for arbitrary arrangements of a large number of molecules, as well as for periodic or aperiodic molecular arrays. We identify areas of research for further improving the accuracy of the method, as well as new fundamental and technological research avenues based on the use of the T‐matrices of molecules and molecular ensembles for quantifying their degrees of symmetry breaking. We provide T‐matrix‐based formulas for computing traditional chiro‐optical properties like (oriented) circular dichroism, and also for quantifying electromagnetic duality and electromagnetic chirality. The formulas are valid for light‐matter interactions of arbitrarily‐high multipolar orders.
Photoinduced Release of DNA‐Binding Ligands from the [4+4] Dimers of Benzo[b]quinolizinium and Anthracene Derivatives
Authors: Berdnikova Daria V. , Heider Josef , Ihmels Heiko , Sewald Norbert , Pithan Phil M.
Published: February 2020

It is demonstrated with four representative examples that the dimers of benzo[b]quinolizinium, dibenzo[b,g]quinolizinium and anthracene derivatives may be used as a source to release the DNA‐binding monomers upon irradiation in the presence of DNA, as determined by monitoring the reaction with absorption and CD spectroscopy. Specifically, the dimers of the benzo[b]quinolizinium turned out to be suitable for this purpose as the ligand is formed rapidly in the presence of DNA and subsequently intercalates into the nucleic acid. In combination with the promising biological properties and bioanalytical value of benzo[b]quinolizinium derivatives, this approach may be used as a general method to generate these functional dyes with spatio‐temporal control.
Formation of solitary structures and envelope solitons in electron acoustic wave in inner magnetosphere plasma with suprathermal ions
Authors: Sarkar Jit , Chandra Swarniv , Goswami Jyotirmoy , Ghosh Basudev
Published: February 2020

The propagation of electron acoustic solitary waves is investigated in magnetized two‐temperature electron plasma with supra‐thermal ion. By using the reductive perturbation technique, the Korteweg de‐Vries (KdV) equation is derived. Later solving this equation, a solitary wave solution has been derived. These are mainly in astrophysical plasmas where changes of local charge density, temperature, and energy of particles produce considerable effects on the plasma system. The effects of supra‐thermality, density, and Mach number on solitary structures are studied in detail. The results show that the supra‐thermal index (κ) and ion to electron temperature ratio (σ) alters the regime where solitary waves may exist. While studying the solitary profile for different parametric variation some interesting conclusion can be drawn; it is shown that the solitary profile becomes flatter. This can be due to the thermal energy associated with the hot electrons. However, with the increase in ion density with respect to the cold electrons' density, the solitary waves become steeper and sharper. This is due to the comparatively heavier mass of ions. The density of cold electron also increases the solitary structures in a similar manner. The higher the density of cold electrons, sharper will be the profile. The above findings will be helpful in understanding many astrophysical phenomena and data obtained by space missions. For a further study, we keep the investigation of the formation of other kinds of stationary structures like shocks, double layers, etc.
Tuning the Copper(II)/Copper(I) Redox Potential for More Robust Copper‐Catalyzed C–N Bond Forming Reactions
Authors: Cope James D. , Valle Henry U. , Hall Ruby S. , Riley Kathleen M. , Goel Ekta , Biswas Saborni , Hendrich Michael P. , Wipf David O. , Stokes Sean L. , Emerson Joseph P.
Published: February 2020

Complexes of copper and 1,10‐phenanthroline have been utilized for organic transformations over the last 50 years. In many cases these systems are impacted by reaction conditions and perform best under an inert atmosphere. Here we explore the role the 1,10‐phenanthroline ligand plays on the electronic structure and redox properties of copper coordination complexes, and what benefit related ligands may provide to enhance copper‐based coupling reactions. Copper(II) triflate complexes bearing 1,10‐phenanthroline (phen), ([Cu(phen)2(OTf)]OTf, 1) and oxidized derivatives of phen including [Cu(edhp)2](OTf)2 (2), [Cu(pdo)2](OTf)2 (3), [Cu(dafo)2](OTf)2 (4) were prepared and characterized. X‐ray crystallographic data show these related ligands subtly impacted the coordination geometry of the copper(II) ion. Complexes 1–3 had only incremental changes to the redox properties of the copper ions, complex 4 showed a drastically different redox potential affording a remarkably air stable copper(I) complex. Complexes 1–4 were then used to catalyze the C–N bond forming cross coupling between imidazole and various boronic acid substrates, where the increased stability of the copper(I) species in complex 4 appears to better support Chan‐Evans‐Lam (CEL) cross couplings.
Production of γ‐Valerolactone from One‐Pot Transformation of Biomass‐Derived Carbohydrates Over Chitosan‐Supported Ruthenium Catalyst Combined with Zeolite ZSM‐5
Authors: Wang Tianlong , He Jianghua , Zhang Yuetao
Published: February 2020

It remains as a challenge to directly transform the biomass‐derived C5 carbohydrates, such as furfural (FF) and its upstream product xylose and hemicellulose, to γ‐valerolactone (GVL), a versatile renewable chemical platform, due to various restrictions in the current synthetic strategies. Using formic acid as green hydrogen source, we synthesized the recyclable chitosan‐Ru/PPh3 catalyst system, effective for both the hydrogenation of FF to furfuryl alcohol (FAL) and the reduction of levulinic acid (LA) or ethyl levulinate (EL) to GVL, affording up to 99 % product yields. The combination of chitosan‐Ru/PPh3 with ZSM‐5 could successfully achieve up to 79 % yield of GVL from one‐pot conversion of FF under mild condition. Preliminary studies indicated that this method could also be applied to the direct conversion of biomass‐derived C5 carbohydrates such as xylose and hemicellulose to GVL in 37 % or 30 % yield, respectively.
The Red Color of Life Transformed – Synthetic Advances and Emerging Applications of Protoporphyrin IX in Chemical Biology
Authors: Sitte Elisabeth , Senge Mathias O.
Published: February 2020

Protoporphyrin IX (PPIX) is the porphyrin scaffold of heme b, a ubiquitous prosthetic group of proteins responsible for oxygen binding (hemoglobin, myoglobin), electron transfer (cytochrome c) and catalysis (cytochrome P450, catalases, peroxidases). PPIX and its metallated derivatives frequently find application as therapeutic agents, imaging tools, catalysts, sensors and in light harvesting. The vast toolkit of accessible porphyrin functionalization reactions enables easy synthetic modification of PPIX to meet the requirements for its multiple uses. In the past few years, particular interest has arisen in exploiting the interaction of PPIX and its synthetic derivatives with biomolecules such as DNA and heme‐binding proteins to evolve molecular devices with new functions as well as to uncover potential therapeutic toeholds. This review strives to shine a light on the most recent developments in the synthetic chemistry of PPIX and its uses in selected fields of chemical biology.
Experimental study of low‐concentration gas explosion in large‐scale pipeline
Authors: Li Lei , Zhang Zhigang , Liu Peng , Wang Kequan , Zhang Jun , Li Xuelong
Published: February 2020

Low‐concentration gas is one of the most realistic and reliable supplementary or alternative energy sources of conventional natural gas, which has a wide range of applications. However, this gas is flammable and explosive during pipeline transportation and easily causes an explosion. In order to achieve safe transmission, the explosion characteristics and propagation law of low‐concentration gas are systematically studied through a large‐scale pipeline experimental system. We found that the peak pressure of low‐concentration gas explosion in pipeline has a quadratic function relationship with the propagation distance. Moreover, the peak pressure of gas explosion initially decreases from the explosion source, and then a turning point appears after a certain distance of propagation, which is followed by a sharp increase of peak pressure of gas explosion. The explosion pressure becomes maximum at the outlets of a pipeline. The arrival time of explosion flame is logarithmically relevant to propagation distance, while the speed of flame propagation gradually increases along with the increase of propagation distance. The flame propagation is faster at the exit point. In addition, the diameter of pipeline has also an important influence on the explosion propagation process of low‐concentration gas. So, the larger the diameter, the higher the explosion pressure. The explosion pressure of DN700 pipeline is obviously higher than that of DN500, and the explosion pressure rises faster; the speed of flame propagation of gas explosion in DN700 pipeline is also higher than that in DN500 pipeline. This study provides a theoretical reference for the prevention and control of explosion accidents in low‐concentration gas pipelines.
Enhanced performance analysis of a hybrid spectrum sliced‐wavelength division multiplexing‐mode division multiplexing‐orthogonal frequency division multiplexing based radio‐over‐free space optics
Authors: Grover Amit , Sheetal Anu , Dhasarathan Vigneswaran
Published: February 2020

In this work, we report the use of self‐phase modulation in a high nonlinearity fiber for super continuum frequency generation which is spectrum‐sliced using a demultiplexer. Four channels (193‐193.225 THz) are sliced with 75 GHz channel spacing. Each wavelength channel transports two distinct sub‐channels with 20 Gbit/s‐40 GHz data rate over different Laguerre Gaussian spatial modes (LG02 and LG03) using the proposed hybrid spectrum sliced‐wavelength division multiplexing‐mode division multiplexing based orthogonal frequency division multiplexing‐radio‐over‐free space optics link. The performance of the proposed link is investigated using numerical simulations. 160 Gbit/s‐320 GHz data is transmitted at 20 km for clear conditions with reliable performance. We have also analyzed the link performance under different level of fog weather. Further to maximize the link reach, we have proposed an enhanced detection at the receiver terminal. The results of numerical investigation of the link show an improvement of 40 dB in signal‐to‐noise ratio and received power under different weather conditions using the proposed detection technique.
Constructal design of longitudinally finned tubes cooled by forced convection
Authors: Yehia Abbas Noor , Waheed Mustafa Ahmed , Kheir Aldeen Abbas Asker Mohammed
Published: February 2020

The constructal design method is used in the present study to find the configuration of longitudinally finned tubes cooled by forced convection. The finned tubes are arranged in parallel inside a fixed two‐dimensional domain. Two degrees of freedom inside the domain are considered for the design. The first degree of freedom is the tube‐to‐tube spacing, and the second is the length of the longitudinal fin. For both these degrees of freedom, a three‐fin position inside the domain is considered. The fin is placed in the front, back, and front and back of the tube in the first, second, and third positions, respectively. Maximization of the heat flow density (heat transfer/volume) from the finned tubes to the cold cross flow is the objective function of the present study. For the three fin positions, the constant pressure difference between the upstream and the downstream drives the cross flow. The dimensionless continuity, momentum, and energy equations for two dimensional, steady, and incompressible flows are solved by discretizing it according to the finite volume method. The thermal condition of the fins and the tubes is constant surface temperature. The dimensionless pressure drop known as Bejan number is varied in the range of 103 ≤ Be ≤ 105. The fin length is changed from Lf = 0 (unfinned tube) to Lf = 0.2, 0.4, and 0.4. The tubes are cooled by air (Prandtl number = 0.71). The results illustrated that for the considered Bejan numbers and fin positions, the spacing between the unfinned and the finned tubes can be adjusted to optimal spacing such that the heat flow from the tubes to the coolant is maximum.
Non‐coenzyme role of vitamin B1 in RANKL‐induced osteoclastogenesis and ovariectomy induced osteoporosis
Authors: Ma Qinyu , Liang Mengmeng , Wang Yaxi , Ding Ning , Wu Yutong , Duan Lianli , Yu Tao , Lu Yanzhu , Xu Jianzhong , Kang Fei , Dou Ce
Published: February 2020

Vitamins B are co‐enzymes participating in energy metabolic pathways. While some vitamins B are known affecting bone homeostasis, the effects of vitamin B1 (thiamine) on bone health remains unclear. In our study, we used cell counting kit‐8, tartrate‐resistant acid phosphatase stain, actin cytoskeleton stain, and pit formation assay to evaluate the effect of thiamine on osteoclast differentiation, formation, and function, respectively. Then we used dichloro‐dihydro‐fluorescein diacetate assay to investigate reactive oxygen species (ROS) generation and removal. Osteoporosis model by ovariectomy was established for animal experiments. We found that thiamine had inhibitory effect on osteoclast differentiation. And its inhibitory role on osteoclast differentiation is in a dose‐dependent way. Mechanistically, ThDP suppresses intracellular ROS accumulation and unfolded protein response signaling during osteoclastogenesis via inhibiting Rac‐Nox1/2/4 and intracellular inositol‐requiring protein‐1α/X‐box‐binding protein pathways, respectively. Osteoporotic mice treated with thiamine rich dietary showed better bone strength relative to thiamine deficient dietary. Our study explored the non‐coenzyme inhibitory functions of B1 vitamin in receptor activator of nuclear factor κB ligand induced osteoclastogenesis and uncovered the significance of B1 vitamin in bone health.
Interaction between miRNAs and signaling cascades of Wnt pathway in chronic lymphocytic leukemia
Authors: Bhattacharya Manojit , Sharma Ashish Ranjan , Sharma Garima , Patra Bidhan Chandra , Lee Sang‐Soo , Chakraborty Chiranjib
Published: February 2020

Chronic lymphocytic leukemia (CLL), a severe problem all over the world and represents around 25% of all total leukemia cases, is generating the need for novel targets against CLL. Wnt signaling cascade regulates cell proliferation, differentiation, and cell death processes. Thus, any alteration of the Wnt signaling pathway protein cascade might develop into various types of cancers, either by upregulation or downregulation of the Wnt signaling pathway protein components. In addition, it is reported that activation of the Wnt signaling pathway is associated with the transcriptional activation of microRNAs (miRNAs) by binding to its promoter region, suggesting feedback regulation. Considering the protein regulatory functions of various miRNAs, they can be approached therapeutically as modulatory targets for protein components of the Wnt signaling pathway. In this article, we have discussed the potential role of miRNAs in the regulation of Wnt signaling pathway proteins related to the pathogenesis of CLL via crosstalk between miRNAs and Wnt signaling pathway proteins. This might provide a clear insight into the Wnt protein regulatory function of various miRNAs and provide a better understanding of developing advanced and promising therapeutic approaches against CLL.
Comparison of the serum level of interleukin‐4 in patients with brucellosis and healthy controls
Authors: Eini Peyman , Majzoobi Mohammad Mahdi , Ghasemi Basir Hamid Reza , Moosavi Zahra , Moradi Abbas
Published: February 2020

Introduction

Evaluation of cytokines such as interleukin‐4 (IL‐4) can be an important tool in examining immune responses to brucellosis. Also, determining the response rate to treatment is necessary for controlling and eradicating of disease. The review of previous studies reveals contradictory results that require further research in this regard. The aim of this study was to compare the serum level of IL‐4 in patients with brucellosis and healthy controls.

Material and Methods

In this descriptive‐analytical study for comparison of two groups, a total of 165 participants, including 83 patients with brucellosis and 82 non‐infected people, were evaluated after matching of sex and age in Hamadan (northwest of Iran) in 2017 and the serum level of IL‐4 was compared by ELISA method. The collected data were analyzed by SPSS software version 21 at 95% significant level.

Results

Mean of age in the case and control groups were 50.25 ± 16.01 and 43.26 ± 15.6 years, respectively. The serum levels of IL‐4 in the case and control groups were 1.42 ± 0.51 pg/mL and 1.31 ± 1.02 pg/mL, respectively. Based on the non‐parametric Mann‐Whitney test, the IL‐4 level was significantly higher in the case group, compared with the control (P < .001), but no statistically significant relationship was found between serum levels of IL‐4 with age, sex, and serologic titers of Wright and 2ME.

Conclusion

In patients with brucellosis, the level of IL‐4 increases independently of the duration and severity of the disease, which indicates the role of this cytokine of immune system in this infectious disease.
Isometric subgraphs for Steiner distance
Authors: Weißauer Daniel
Published: February 2020

Let G be a connected graph and a length‐function on the edges of G. The Steiner distance sdG(A) of A ⊆ V(G) within G is the minimum length of a connected subgraph of G containing A, where the length of a subgraph is the sum of the lengths of its edges. It is clear that every subgraph H ⊆ G, endowed with the induced length‐function ℓ∣E(H), satisfies sdH(A) ≥ sdG(A) for every A ⊆ V(H). Given an integer k ≥ 2, we call H ⊆ G k‐isometric in G if equality is attained for every A ⊆ V(H) with ∣A∣ ≤ k. A subgraph is fully isometric if it is k‐isometric for every . It is easy to construct examples of graphs H ⊆ G such that H is k‐isometric, but not (k + 1)‐isometric, so this defines a strict hierarchy of properties. We are interested in situations in which this hierarchy collapses in the sense that if H ⊆ G is k‐isometric, then H is already fully isometric in G. Our first result of this kind asserts that if T is a tree and T ⊆ G is 2‐isometric with respect to some length‐function ℓ, then it is fully isometric. This fails for graphs containing a cycle. We then prove that if C is a cycle and C ⊆ G is 6‐isometric, then C is fully isometric. We present an example showing that the number 6 is indeed optimal. We then develop a structural approach toward a more general theory and present several open questions concerning the big picture underlying this phenomenon.
Trabecular bone score, a new bone quality index, is associated with severe periodontitis
Authors: Niramitchainon Chutinun , Mongkornkarn Sanutm , Sritara Chanika , Lertpimonchai Attawood , Udomsak Artit
Published: February 2020

Background

The association between systemic bone loss and periodontitis remains unresolved; and the trabecular bone score (TBS) is a new index for assessing decreased bone quality. Therefore, this cross‐sectional study investigated the association between TBS and severe periodontitis.

Methods

Eight hundred and five Thai participants, aged 30 to 82 years, underwent bone quality assessment. Their mean TBS was calculated from dual‐energy X‐ray absorptiometry images at the L1 to L4 lumbar spine using TBS software. Each participant was classified as normal, partially degraded, or degraded TBS. Full‐mouth periodontal examinations determined plaque score, probing depth, clinical attachment level (CAL), and the number of remaining teeth. The participants were classified as non‐severe or severe periodontitis. Differences in periodontal parameters between the TBS groups were analyzed using one‐way ANOVA. The association between TBS and severe periodontitis was assessed with multivariate binary logistic regression. For severe periodontitis, the additive interaction between TBS and oral hygiene status was also analyzed.

Results

The mean CAL was 0.9‐mm higher in the degraded TBS group compared with the normal TBS group. Degraded TBS was associated with severe periodontitis with an adjusted odds ratio (OR) of 2.10 (95% confidence interval [CI] = 1.03 to 4.26). The combination of degraded TBS and plaque score ≥80% increased the adjusted OR to 5.71 (95% CI = 1.15 to 28.43).

Conclusions

Degraded TBS is associated with severe periodontitis and has a synergistic effect with poor oral hygiene, suggesting monitoring decreased bone quality and good oral hygiene for promoting the periodontal‐systemic health of these individuals.
Investigation on the effectiveness of the repair method 8.3 ''Corrosion protection by increasing electrical resistivity'' in chloride‐containing concrete Part 1: Overview and recognition of Prof. Raupach's contribution
Authors: Breit Wolfgang , Dauberschmidt Christoph
Published: February 2020

The repair method 8.3 “Corrosion protection by increasing the electrical resistance” according to EN 1504 (or the repair principle W‐Cl according to the DAfStb directive “Protection and repair of concrete building materials”) represents a technically and economically interesting method for the repair of chloride‐contaminated concrete components. The coating applied as part of the repair principle prevents further water absorption of the concrete and, due to its permeability to water vapor, allows the concrete to dehydrate. Over time, this leads to an increase in the electrolytic resistance and thus to a reduction in the rate of corrosion. The article deals with the basic principles underlying this repair principle, deals with the current regulatory situation, and shows the responsibility of the expert planner. Groundbreaking studies on the effectiveness of the repair principle were carried out by Prof. Raupach, to whom this article is dedicated, and are summarized in this paper. The objective of the new studies, which build on the aforementioned research, is to establish universally accepted application limits, for example, the level of the remaining chloride concentration, for the low‐risk use of this repair method.
Genetic and clinical findings of panel‐based targeted exome sequencing in a northeast Chinese cohort with retinitis pigmentosa
Authors: Sun Yan , Li Wei , Li Jian‐kang , Wang Zhuo‐shi , Bai Jin‐yue , Xu Ling , Xing Bo , Yang Wen , Wang Zi‐wei , Wang Lu‐sheng , He Wei , Chen Fang
Published: February 2020

Background

Panel‐based targeted exome sequencing was used to analyze the genetic and clinical findings of targeted genes in a cohort of northeast Chinese with retinitis pigmentosa.

Methods

A total of 87 subjects, comprising 23 probands and their family members (total patients: 32) with confirmed retinitis pigmentosa were recruited in the study. Panel‐based targeted exome sequencing was used to sequence the patients and family members, all subjects with retinitis pigmentosa underwent a complete ophthalmologic examination.

Results

Of the 23 probands, the clinical manifestations include night blindness, narrowing of vision, secondary cataracts, choroidal atrophy, color blindness, and high myopia, the average age of onset of night blindness is 12.9 ± 14 (range, 0–65; median, 8). Posterior subcapsular opacities is the most common forms of secondary cataracts (nine cases, 39.1%), and peripheral choroidal atrophy is the most common form of secondary choroidal atrophy (12 cases, 52.2%). Of these probands with complication peripheral choroidal atrophy, there were eight probands (66.7%, 8/12) caused by the pathogenic variation in USH2A gene. A total of 17 genes and 45 variants were detected in 23 probands. Among these genes, the commonest genes were USH2A (40%; 18/45), RP1 (15.6%; 7/45), and EYS (8.9%; 4/45), and the top three genes account for 56.5% (13/23) of diagnostic probands. Among these variants, comprising 22 (48.9%) pathogenic variants, 14 (31%) likely pathogenic variants, and nine (20%) uncertain clinical significance variants, and 22 variants was discovered first time. Most of the mutations associated with RP were missense (53.3%, 24/45), and the remaining mutation types include frameshift (35.6%, 16/45), nonsense (6.7%, 3/45), and spliceSite (4.4%, 2/45). Among the probands with mutations detected, compound heterozygous forms was detected in 13 (56.5%, 13/23) probands, and digenic inheritance (DI) forms was detected in five (21.7%, 5/23) probands.

Conclusion

Panel‐based targeted exome sequencing revealed 23 novel mutations, recognized different combinations forms of variants, and extended the mutational spectrum of retinitis pigmentosa and depicted common variants in northeast China.
A piece of the C6H9+ potential energy surface: Rearrangement of spiropentylmethyl cation and an elegant nonclassical spiro[2.3]hex‐5‐yl cation
Authors: Shobe David S.
Published: February 2020

Stationary points in a region of the C6H9+ potential energy surface was explored using the CBS‐QB3 method. The region includes the spiropentylmethyl cation and all three bicyclohexyl bridgehead cations. The relative energies of these bicyclohexyl cations are −54 kJ/mol for bicyclo[2.2.0]hex‐1‐yl cation and −75 kJ/mol for bicyclo[2.1.1]hex‐1‐yl cation, with spiropentylmethyl cation being 0 kJ/mol. Bicyclo[2.1.1]hex‐1‐yl cation is a transition state, while bicyclo[3.1.0]hex‐1‐yl cation is not a stationary point after all, but rearranges without barrier to 2‐methylenecyclopentyl cation. Although spiropentylmethyl cation and spiro[2.3]hex‐4‐yl cation are local minima on the CBS‐QB3 potential energy surface, their existence is questioned. Spiro[2.3]hex‐5‐yl cation has an unusual structure, with the central carbon having five nearest neighbors with interatomic distances between 1.5 and 1.7 Å. The results for rearrangement of the spiropentylmethyl cation are in general agreement with previous solvolysis studies.