bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of Near Surface Seismic Refraction for Geotechnical Parameters in Opolo, Yenagoa of Bayelsa State
Authors: Omonefe Francis , Desmond Eteh , Ebiegberi Oborie , Karo Oboshenure Kingsley 
Published: October 2019

Three surface refraction seismic profiles were conducted in a site targeted for huge construction in an underdeveloped area in Opolo, Yenagoa city to portray some of the subsurface soil engineering characteristics for the purposes of construction. The Generalized Reciprocal Method (GRM) was used to interpret the acquired P and S-wave. Various shallow rock engineering parameters such as Oedometric modulus, Concentration Index, Material Index, Lame’s constant, Density Gradient, Stress Ratio, Shear modulus, Bearing capacity, and N-value were calculated in other to assess the strength of the subsurface from a geophysical and engineering perspective. The values from the seismic velocity and strength parameters indicates that the bedrock layer (layer 3) of the area studied is characterized by more competent rock quality than layer 1 and 2. Hence, the Opolo site is suggested for construction activities with percussive measures.
Assessing Qualities of Different Sources of Water for Mixing Concrete
Authors: Yalley Peter P. , Appiadu-Boakye Kennedy , Adzraku Wisdom D. 
Published: October 2019

This study investigates the effects of water sources on concrete properties. A mix ratio of 1:1.5:3 with 0.5w/c was used in mixing the concrete. Water from the Stream, the hand-dug well and the borehole were used for the experiments with pipe borne water serving as the control. Cubes and beams were cast and tested for compression and flexural strengths respectively at 7-day and 28-day curing ages. Chemical and physical properties of the water samples were also tested. The results indicate that the chemical impurities of all the water types were within the limits given in GS 175-1:2009, EN 1008, ASTM C94 and AS 1379. The physical specifications were all satisfactory, except for the stream water. The water sources had no significant effect on the workability of concrete. Effects of efflorescence were not observed on hardened concrete specimens obtained from any of the water sources. Concrete Specimens mixed with water from the hand-dug well had the highest compressive strength.
Wafer Tape Selection Analysis for Adhesion Problem Mitigation
Authors: S. Bacquian Bryan Christian , I. Gomez Frederick Ray 
Published: October 2019

Wafer passivation or the protective layer of the internal circuitry of the die plays a major role of providing protection and the isolation of electrical stability of the active circuit on the top area of the wafer. Passivation is normally a screen of an oxide layer on the surface of the silicon wafer or the carrier of internal circuitry of the die. Passivation is normally in the form of polyimide or a glass material. From the wafer structure, it is important to cover the active circuit to ensure no other noises will be induced to the wafer. Inclusion of the passivation layer will help maximize the functionality of the semiconductor device thus eliminating noises coming from the external sources.
As the integrated circuit (IC) package goes thinner, the requirement of having the active circuit or the die thinner is the main concern during the wafer preparation process. Wafer backgrinding or wafer thinning is the focal process involved to satisfy such requirement. Prior performing the wafer thinning process, the application of tape, normally in a form of polyolefin or polyvinyl chloride should be performed to eliminate contamination and protects the active layer of the wafer during the process. However, there should be enough adhesion between the wafer and the thinning tape itself. High adhesion strength may lead to adhesive remains or worst, passivation will be peeled off from the active layer of the wafer.
Adhesion to the passivation layer should be properly evaluated and monitored in such way that will eliminate adhesive remains during detaping process after wafer thinning. The effect of adhesion strength could be predicted by properly selecting thinning or protective tape to be used. Higher adhesion strength could be achieved but due to criticality of passivation to tape adhesion, ultra-violet (UV) process should be included to substantially decreased the adhesion. The importance of UV exposure is also discussed on this paper.
Adaptive Design and Performance Evaluation of Compact Acoustic Enclosures Built with GFRP for Portable Mini-generators
Authors: Agbo Cornelius Ogbodo Anayo 
Published: October 2019

A simple, portable and effective design for enclosing portable generators to reduce the radiated noise has remained a daunting challenge to noise control advocates in many developing countries. This research aims to use an adaptive design approach to create an enclosure for minimizing portable mini-generator noise. The noise characteristics of the mini-generators was ascertained and construction of a 730 by 640 by 600 mm enclosure was accomplished by using glass fiber reinforced plastic (GFRP) to build a double walled enclosure surfacing and rock wool as the sandwiched absorbing material. The sound pressure level (SPL) around the generator before and after the application of the enclosure was measured and evaluated. The results obtained showed that the acoustic enclosure could achieve an insertion loss of up to 16 dB (A) at a distance of 1.0 m. Also, the heat transfer characteristic of the enclosure design was put into consideration as well as the requirements of the engine air aspiration and cooling inside of the enclosure. Incorporation of fans in the acoustic enclosure design increased convectional fresh air circulation into, and discharge of the heat generated in, the enclosure, thus maintaining a safe temperature of about 40oC inside of the acoustic enclosure at the generator operating maximum load.
Practical Chromatic Aberration Correction in Virtual Reality Displays Enabled by Cost‐Effective Ultra‐Broadband Liquid Crystal Polymer Lenses
Authors: Zhan Tao , Zou Junyu , Xiong Jianghao , Liu Xiaomin , Chen Hao , Yang Jilin , Liu Sheng , Dong Yajie , Wu Shin‐Tson 
Published: October 2019

AbstractChromatic aberration (CA) is a critical issue in immersive virtual reality displays. The current digital compensation method can reduce the CA by pre‐processing the image contents but at the cost of extra memory space, processing time, and power consumption. Moreover, it is not possible to digitally compensate the CA within each color channel. Here, a practical optical approach is presented to correct the CAs, including the sub‐channel ones, in the virtual reality system, whose functionality is verified by both ray‐tracing analysis and experimental results. In this device, a compact ultra‐broadband Pancharatnam‐Berry phase lens (PBL) with complex axial molecular structure is fabricated and then hybridized with a refractive Fresnel lens. Due to their opposite chromatic dispersion, the system's CA is significantly reduced. To eliminate ghost image from the zero‐order leakage of PBL, a broadband circular polarizer is implemented to block the stray light. As a result, clear image within the entire 100° field‐of‐view is achieved. The proposed large‐size cost‐efficient broadband wide‐view flat optics can practically benefit not only virtual reality displays but also general imaging systems for practical applications and scientific research.
Site‐Selective Alkoxylation of Benzylic C−H Bonds by Photoredox Catalysis
Authors: Lee Byung Joo , DeGlopper Kimberly S. , Yoon Tehshik P. 
Published: October 2019

AbstractMethods that enable the direct C−H alkoxylation of complex organic molecules are significantly underdeveloped, particularly in comparison to analogous strategies for C−N and C−C bond formation. In particular, almost all methods for the incorporation of alcohols by C−H oxidation require the use of the alcohol component as a solvent or co‐solvent. This condition limits the practical scope of these reactions to simple, inexpensive alcohols. Reported here is a photocatalytic protocol for the functionalization of benzylic C−H bonds with a wide range of oxygen nucleophiles. This strategy merges the photoredox activation of arenes with copper(II)‐mediated oxidation of the resulting benzylic radicals, which enables the introduction of benzylic C−O bonds with high site selectivity, chemoselectivity, and functional‐group tolerance using only two equivalents of the alcohol coupling partner. This method enables the late‐stage introduction of complex alkoxy groups into bioactive molecules, providing a practical new tool with potential applications in synthesis and medicinal chemistry.
Lessons in Strain and Stability: Enantioselective Synthesis of (+)‐[5]‐Ladderanoic Acid
Authors: Hancock Erin N. , Kuker Erin L. , Tantillo Dean J. , Brown M. Kevin 
Published: October 2019

AbstractThe synthesis of structurally complex and highly strained natural products provides unique challenges and unexpected opportunities for the development of new reactions and strategies. Herein, the synthesis of (+)‐[5]‐ladderanoic acid is reported. En route to the target, unusual and unexpected strain release driven transformations were uncovered. This occurrence required a drastic revision of the synthetic design that ultimately led to the development of a novel stepwise cyclobutane assembly by an allylboration/Zweifel olefination sequence.
Manganese(I)‐Catalyzed β‐Methylation of Alcohols Using Methanol as C1 Source
Authors: Kaithal Akash , van Bonn Pit , Hölscher Markus , Leitner Walter 
Published: October 2019

AbstractHighly selective β‐methylation of alcohols was achieved using an earth‐abundant first row transition metal in the air stable molecular manganese complex [Mn(CO)2Br[HN(C2H4PiPr2)2]] 1 ([HN(C2H4PiPr2)2]=MACHO‐iPr). The reaction requires only low loadings of 1 (0.5 mol %), methanolate as base and MeOH as methylation reagent as well as solvent. Various alcohols were β‐methylated with very good selectivity (>99 %) and excellent yield (up to 94 %). Biomass derived aliphatic alcohols and diols were also selectively methylated on the β‐position, opening a pathway to “biohybrid” molecules constructed entirely from non‐fossil carbon. Mechanistic studies indicate that the reaction proceeds through a borrowing hydrogen pathway involving metal–ligand cooperation at the Mn‐pincer complex. This transformation provides a convenient, economical, and environmentally benign pathway for the selective C−C bond formation with potential applications for the preparation of advanced biofuels, fine chemicals, and biologically active molecules
Hollow Zn−Co Based Zeolitic Imidazole Framework as a Robust Heterogeneous Catalyst for Enhanced CO2 Chemical Fixation
Authors: Tang Bo , Li Shuang , Song Wei‐Chao , Li Yan , Yang En‐Cui , Zhao Xiao‐Jun , Li Landong 
Published: October 2019

AbstractThe efficient chemical conversion of carbon dioxide (CO2) into value‐added fine chemicals is an intriguing but challenging route in sustainable chemistry. Herein, a hollow‐structured bimetallic zeolitic imidazole framework composed of Zn and Co as metal centers (H‐ZnCo‐ZIF) has been successfully prepared via a post‐synthetic strategy based on controllable chemical‐etching of the preformed solid ZnCo‐ZIF in tannic acid. The creation of hollow cavities inside each monocrystalline ZIFs could be achieved without destroying the intrinsic frameworks, as characterized by field‐emission scanning electron microscopy, transmission electron microscopy, and X‐ray diffraction technologies. The as‐synthesized H‐ZnCo‐ZIF exhibited remarkable catalytic activity in the cycloaddition of CO2 with epoxides to the corresponding cyclic carbonates, outperforming the solid ZnCo‐ZIF analogue due to the improved mass transfer originating from the hollow structure. More importantly, due to stabilization of metal centers in the ZIF framework by the tannic acid shell, H‐ZnCo‐ZIF exhibited good recyclability, and no activity loss could be observed in six runs. The present study provides a simple and effective strategy to enhance the catalytic performance of ZIFs by creating a hollow structure via chemical etching.
A POSS‐Phosphazene Based Porous Material for Adsorption of Metal Ions from Water
Authors: Soldatov Mikhail , Liu Hongzhi 
Published: October 2019

AbstractThe development of adsorptive materials continues to be an important area of research for removal of heavy metal ions from waste water. The adsorption capacity can be modulated by both physical and chemical modification of the adsorbent. Herein, we combine the unique properties of polyhedral oligomeric silsesquioxane (POSS) and organocyclophosphazene as the building units to synthesize a hybrid porous material, abbreviated as PN‐POSS. The synthetic method follows a Heck reaction between hexa(4‐bromophenoxy)cyclotriphosphazene and octavinylsilsesquioxane (OVS). The Brunauer–Emmett–Teller (BET) analysis shows that the material possesses micro‐ and mesopores of 1.5 and 3.8 nm size and a surface area on the order of 500 m2 g−1. These attributes in combination with the donor ability of the phosphazene units qualify the material for high adsorption of Pb2+, Hg2+ and Cu2+ ions with maximal adsorption capacities on the order of 1326, 1927 and 2654 mg g−1, respectively. The adsorbent exhibits a good regeneration performance and can be effectively used for water treatment.
Ultrasonic extraction, structural characterization, and bioactivities of nonstarch polysaccharides from red yeast rice
Authors: Luo Jia , Sun Qiang , Ma Zubing , Song Jiawen , Wu Chunjie , Li Xiaofang 
Published: October 2019

AbstractRed yeast rice (RYRP) has been utilized for coloring food, brewing wine, and preserving meat, which is also used as a folk medicine for centuries. In this study, a water‐soluble nonstarch polysaccharide from RYRP was extracted by using ultrasonic‐assisted extraction method. By using the Box–Behnken design to optimize the parameters for extracting the RYRP, the maximum extraction yield (3.37 ± 0.78%) was obtained under the optimal extraction conditions as follows: ratio of water to raw material (40 mL/g), extraction temperature (62 °C), extraction time (75 Min), and ultrasonic power (200 W). Moreover, monosaccharide composition analysis showed that RYRP was consisted of mannose, glucosamine, glucose, and galactose with a molar ratio of 0.152:0.015:1:0.149. The molecular weight distribution analysis showed that the average molecular weight of the RYRP fraction was about 3.49 × 103 Da. Furthermore, RYRP exhibited significant antioxidant activities in vitro and the gastrointestinal‐protective effect in vivo using gastrointestinal disorders model mice. RYRP could be explored as a potential source in the pharmaceutical and functional food industries.
Learning curve of laparoscopic living donor right hepatectomy
Authors: Rhu J , Choi G-S , Kwon C H D , Kim J M , Joh J-W 
Published: October 2019

Abstract

Background
The feasibility and learning curve of laparoscopic living donor right hepatectomy was assessed.

Methods
Donors who underwent right hepatectomy performed by a single surgeon were reviewed. Comparisons between open and laparoscopy regarding operative outcomes, including number of bile duct openings in the graft, were performed using propensity score matching.

Results
From 2014 to 2018, 103 and 96 donors underwent laparoscopic and open living donor right hepatectomy respectively, of whom 64 donors from each group were matched. Mean(s.d.) duration of operation (252·2(41·9) versus 304·4(66·5) min; P &lt; 0·001) and median duration of hospital stay (8 versus 10 days; P = 0·002) were shorter in the laparoscopy group. There was no difference in complication rates of donors (P = 0·298) or recipients (P = 0·394) between the two groups. Total time for laparoscopy decreased linearly (R2 = 0·407, β = –0·914, P = 0·001), with the decrease starting after approximately 50 procedures when cases were divided into four quartiles (2nd versus 3rd quartile, P = 0·001; 3rd versus 4th quartile, P = 0·023). Although grafts with bile duct openings were more abundant in the laparoscopy group (P = 0·022), no difference was found in the last two quartiles (P = 0·207).

Conclusion
Laparoscopic living donor right hepatectomy is feasible and an experience of approximately 50 cases may surpass the learning curve.
Mechanoenzymatic Transformations in the Absence of Bulk Water: A More Natural Way of Using Enzymes
Authors: Kaabel Sandra , Friščić Tomislav , Auclair Karine 
Published: October 2019

AbstractMechanochemical enzymatic reactions without bulk water have emerged as a low‐waste and efficient method to access useful chemicals and to depolymerize biomass components in a single step. This emergent mechanoenzymatic reaction strategy is able to take advantage of the stereospecificity, regio‐ and stereoselectivity, as well as renewability of enzymes, while avoiding bulk solvents, offering the opportunity to control the direction of the reaction, bypassing reactant solubility issues, and enabling reactions with water‐sensitive substrates or products. Enzymes are traditionally used in dilute aqueous solution, which is quite different from their crowded, water‐depleted natural environment. This review outlines recent work which demonstrates that enzymes can be equally or even more efficient under mechanochemical conditions, without bulk aqueous or organic solvent.
Effect of Substrate Characteristics and Process Fluid Percolation on Dry Anaerobic Digestion Processes
Authors: Wedwitschka Harald , Gallegos Daniela , Tietze Michael , Reinhold Jürgen , Jenson Earl , Liebetrau Jan , Nelles Michael 
Published: October 2019

AbstractThe dry anaerobic batch digestion process is an organic waste treatment technology most appropriate for the treatment of stackable (non‐free‐flowing) dry organic waste materials. The effect of the process fluid percolation and substrate permeability on methane production of organic household waste was investigated in anaerobic dry digestion trials at pilot scale. The container system consisted of two percolation digesters and a fixed‐bed methane digester. The experimental results indicate that material compaction occurs during the digestion process and can have a negative effect on substrate permeability. Structure material addition reduced material compaction and as a result increased the substrate permeability.
Oriented Crystallization on Organic Monolayers to Control Concomitant Polymorphism
Authors: Bora Pranita , Saikia Basanta , Sarma Bipul 
Published: October 2019

AbstractNucleation events and crystal growth can be guided by molecular recognition at interfaces through intermolecular interactions. The short‐acting antimicrobial sulfa drug sulfathiazole is known for its concomitant crystallization, which has five known polymorphs, due to conformational flexibility and hydrogen‐bond synthon variation. In its development stage of a drug the issue of concomitant crystallization needs to be addressed with respect to patent litigation, including legal actions to protect patents against infringement. A functional self‐assembled monolayer (SAM) of organic thiol on a gold surface has been employed as an efficient approach to control concomitant nucleation of such flexible drugs. The crystallization on a SAM surface is mostly kinetically driven and often leads to the nucleation of novel metastable forms. Spectroscopic, thermal analysis and X‐ray diffraction studies reveal that a previously unknown, sixth form of the drug nucleates on the designed SAM surface.
Unravelling the Promotional Effect of La2O3 in Pt/La‐TiO2 Catalysts for CO2 Hydrogenation
Authors: Wang Zhaoyu , Huang Lijuan , Su Bo , Xu Junli , Ding Zhengxin , Wang Sibo 
Published: October 2019

AbstractThis work reports the preparation of a La2O3‐modified Pt/TiO2 (Pt/La‐TiO2) hybrid through an excess‐solution impregnation method and its application for CO2 hydrogenation catalysis. The Pt/La‐TiO2 catalyst is characterized by XRD, H2 temperature‐programmed reduction (TPR), TEM, X‐ray photoelectron spectroscopy (XPS), Raman, EPR, and N2 sorption measurements. The Pt/La‐TiO2 composite starts to catalyze the CO2 conversion reaction at 220 °C, which is 30 °C lower than the Pt/TiO2 catalyst. The generation of CH4 and CO of Pt/La‐TiO2 is 1.6 and 1.4 times greater than that of Pt/TiO2. The CO2 temperature‐programmed desorption (TPD) analysis confirms the strengthened CO2 adsorption on Pt/La‐TiO2. Moreover, the in situ FTIR experiments demonstrate that the enhanced CO2 adsorption of Pt/La‐TiO2 facilitates the formation of the active Pt–CO intermediate and subsequently boosts the evolution of CH4 and CO. The cycling tests reveal that Pt/La‐TiO2 shows reinforced stability for the CO2 hydrogenation reaction because the La species can prevent Pt nanoparticles (NPs) from sintering. This work may provide some guidance on the development new rare‐metal‐modified hybrid catalysts for CO2 fixation.
Multimetallic Oxynitrides Nanoparticles for a New Generation of Photocatalysts
Authors: Rao Tingke , Saladino Maria Luisa , Fang Yuanxing , Wang Xinchen , Giordano Cristina 
Published: October 2019

AbstractA versatile synthetic strategy for the preparation of multimetallic oxynitrides has been designed and here exemplarily discussed considering the preparation of nanoscaled zinc–gallium oxynitrides and zinc–gallium–indium oxynitrides, two important photocatalysts of new generation, which proved to be active in key energy related processes from pollutant decomposition to overall water splitting. The synthesis presented here allows the preparation of small nanoparticles (less than 20 nm in average diameter), well‐defined in size and shape, yet highly crystalline and with the highest surface area reported so far (up to 80 m2 g−1). X‐ray diffraction studies show that the final material is not a mixture of single oxides but a distinctive compound. The photocatalytic properties of the oxynitrides have been tested towards the decomposition of an organic dye (as a model reaction for the decomposition of air pollutants), showing better photocatalytic performances than the corresponding pure phases (reaction constant 0.22 h−1), whereas almost no reaction was observed in absence of catalyst or in the dark. The photocatalysts have been also tested for H2evolution (semi‐reaction of the water splitting process) with results comparable to the best literature values but leaving room for further improvement.
In‐Cage Interactions in the Clathrate Superconductor Sr8Si46
Authors: Hübner Julia‐Maria , Prots Yurii , Schnelle Walter , Bobnar Matej , König Markus , Baitinger Michael , Simon Paul , Carrillo‐Cabrera Wilder , Ormeci Alim , Svanidze Eteri , Grin Yuri , Schwarz Ulrich 
Published: October 2019

AbstractThe clathrate I superconductor Sr8Si46 is obtained under high‐pressure high‐temperature conditions, at 5 GPa and temperatures in the range of 1273 to 1373 K. At ambient pressure, the compound decomposes upon heating at T=796(5) K into Si and SrSi2. The crystal structure of the clathrate is isotypic to that of Na8Si46. Chemical bonding analysis reveals conventional covalent bonding within the silicon network as well as additional multi‐atomic interactions between Sr and Si within the framework cages. Physical measurements indicate a bulk BCS type II superconducting state below Tc=3.8(3) K.