32 research outputs found
Review of advanced road materials, structures, equipment, and detection technologies
As a vital and integral component of transportation infrastructure, pavement has a direct and tangible impact on socio-economic sustainability. In recent years, an influx of groundbreaking and state-of-the-art materials, structures, equipment, and detection technologies related to road engineering have continually and progressively emerged, reshaping the landscape of pavement systems. There is a pressing and growing need for a timely summarization of the current research status and a clear identification of future research directions in these advanced and evolving technologies. Therefore, Journal of Road Engineering has undertaken the significant initiative of introducing a comprehensive review paper with the overarching theme of âadvanced road materials, structures, equipment, and detection technologiesâ. This extensive and insightful review meticulously gathers and synthesizes research findings from 39 distinguished scholars, all of whom are affiliated with 19 renowned universities or research institutions specializing in the diverse and multidimensional field of highway engineering. It covers the current state and anticipates future development directions in the four major and interconnected domains of road engineering: advanced road materials, advanced road structures and performance evaluation, advanced road construction equipment and technology, and advanced road detection and assessment technologies
Rapid Diagnosis of Mycobacterium marinum Infection on Both Hands using a Combination of Skin Trephination and Metagenomic Next-generation Sequencing
Abstract is missing (Short communication
Hydrothermal synthesis and characterization of a layered zirconium silicate
A layered zirconosilicate composed of SiO4 tetrahedra and ZrO6 octahedra was hydrothermally synthesized in the presence of tetramethylammonium hydroxide. The layered material with a nominal composition Na2ZrSi4O11¡xH2O was further characterized by XRD, SEM, thermogravimetric analysis, UV-Raman spectroscopy and single- and triple-quantum 23Na and 29Si MAS NMR spectroscopy. There are no ZrâOâZr chains in the framework structure implying that the ZrO6 octahedra are isolated by SiO4 tetrahedra. 23Na MAS NMR indicates at least two different Na sites in the framework of SZS and the Na located in the interlayer can be exchanged by TMAOH, leading to an increase of the interlayer spacing. The layered zirconosilicate SZS has a high activity in the isomerization of glucose to fructose in water and can be reused.status: publishe
Dehydration of glucose to 5-Hydroxymethylfurfural using Nb-doped Tungstite
Dehydration of glucose to 5-hydroxymethylfurfural (HMF) remains a significant problem in the context of the valorization of lignocellulosic biomass. Hydrolysis of WCl6 and NbCl5 leads to precipitation of Nb-containing tungstite (WO3â
H2O) at low Nb content and mixtures of tungstite and niobic acid at higher Nb content. Tungstite is a promising catalyst for the dehydration of glucose to HMF. Compared with Nb2O5, fewer by-products are formed because of the low Brønsted acidity of the (mixed) oxides. In water, an optimum yield of HMF was obtained for NbâW oxides with low Nb content owing to balanced Lewis and Brønsted acidity. In THF/water, the strong Lewis acidity and weak Brønsted acidity caused the reaction to proceed through isomerization to fructose and dehydration of fructose to a partially dehydrated intermediate, which was identified by LC-ESI-MS. The addition of HCl to the reaction mixture resulted in rapid dehydration of this intermediate to HMF. The HMF yield obtained in this way was approximately 56â% for all tungstite catalysts. Density functional theory calculations show that the Lewis acid centers on the tungstite surface can isomerize glucose into fructose. Substitution of W by Nb lowers the overall activation barrier for glucose isomerization by stabilizing the deprotonated glucose adsorbate.\u3cbr/\u3
The nature of strong Brønsted acidity of Ni-SMM clay
The origin of the high Brønsted acidity of Ni-SMM (Ni-substituted synthetic mica-montmorillonite; beidellite structure) clays was investigated. Ni-SMM clays with varying F content, SMM with F and Ni-SMM without F in the structure were synthesized under hydrothermal conditions. Ni-SMM clays with intermediate F content contained very strong Brønsted acid sites. The optimum Ni-SMM sample outperformed zeolites such as H-ZSM-5 and H-USY (ultrastabilized Y) in alkane hydroisomerization. Infrared spectroscopy with different probe molecules shows that Ni-SMM contains two types of BAS. In addition to acid sites also observed in other clays and amorphous silica-alumina, Ni-SMM contains a small number of acid sites that are stronger than the acid sites in zeolites. The number of such sites does not depend on Ni-SMM reduction. A small amount of strongest Brønsted acid sites positions the catalytic activity of Ni-SMM clay beyond that of zeolites. Periodic density functional theory calculations show that the substitution of octahedral [Al3+-O]+ by [Ni2+-F]+ causes high acidity of the interlayer proton connected to the aluminium-occupied tetrahedron. This explains why Ni-SMM (no F in the structure) and SMM with F (no Ni in the structure; F replaces only structural OH) exhibit conventional clay acidity. The presence of Ni in the octahedral layer leads to isomorphous substitution of bridging O anions that connect the octahedral with the tetrahedral layer by F. The electron-withdrawing nature of the bridging F induces the unusually high acidity of the interlayer protons in Ni-SMM
Organocatalytic Dehydration of Fructose-Based Carbohydrates into 5âHydroxymethylfurfural in the Presence of a Neutral Inner Salt
A series of organic
sulfonate inner salts, viz., aprotic imidazolium-
and pyridinium-based zwitterions bearing sulfonate
groups (âSO3â), were synthesized
for the catalytic conversion of fructose-based carbohydrates into
5-hydroxymethylfurfural (HMF). The dramatic cooperation of both the
cation and anion of inner salts played a crucial role in the HMF formation.
The inner salts have excellent solvent compatibility, and 4-(pyridinium)butane
sulfonate (PyBS) affords the highest catalytic activity with 88.2
and 95.1% HMF yields at almost full conversion of fructose in low-boiling-point
protic solvent isopropanol (i-PrOH) and aprotic solvent
dimethyl sulfoxide (DMSO), respectively. The substrate tolerance of
aprotic inner salt was also studied through changing the substrate
type, demonstrating its excellent specificity for catalytic valorization
of fructose-moiety-containing C6 sugars, such as sucrose and inulin.
Meanwhile, the neutral inner salt is structurally stable and reusable;
after being recycled four times, the catalyst showed no appreciable
loss of its catalytic activity. The plausible mechanism has been elucidated
based on the dramatic cooperative effect of both the cation and sulfonate
anion of inner salts. The noncorrosive, nonvolatile, and generally
nonhazardous aprotic inner salt used in this study will benefit many
biochemical-related applications
Insights into the adaptive evolution of chromosome and essential traits through chromosome-level genome assembly of Gekko japonicus
Summary: Gekko japonicus possesses flexible climbing and detoxification abilities under insectivorous habits. Still, the evolutionary mechanisms behind these traits remain unclarified. This study presents a chromosome-level G. japonicus genome, revealing that its evolutionary breakpoint regions were enriched with specific repetitive elements and defense response genes. Gene families unique to G. japonicus and positively selected genes are mainly enriched in immune, sensory, and nervous pathways. Expansion of bitter taste receptor type 2 primarily in insectivorous species could be associated with toxin clearance. Detox cytochrome P450 in G. japonicus has undergone more birth and death processes than biosynthesis-type P450 genes. Proline, cysteine, glycine, and serine in corneous beta proteins of G. japonicus might influence flexibility and setae adhesiveness. Certain thermosensitive transient receptor potential channels under relaxed purifying selection or positive selection in G. japonicus might enhance adaptation to climate change. This genome assembly offers insights into the adaptive evolution of gekkotans
Flexible n-type thermoelectric films based on Cu-doped Bi2Se3 nanoplate and Polyvinylidene Fluoride composite with decoupled Seebeck coefficient and electrical conductivity
We report on the fabrication of flexible and freestanding n-type thermoelectric Cu intercalated Bi2Se3 nanoplatelet/Polyvinylidene Fluoride (PVDF) composite films. The optimized power factor and figure of merit (ZT) of the Cu0.1Bi2Se3 nanoplatelet/PVDF composites are 103 mu W m(-1) K-2 and 0.10 at 290 K, respectively, which are one of the highest values for n-type thermoelectric films. The mechanism by which the Seebeck coefficient and electrical conductivity can be partially decoupled is explained in details: PVDF can not only grantee the robust and flexibility but also create a high trap state by introducing the energy barrier at the organic/inorganic interface, thus a high level of Seebeck coefficient is maintained for the composite system while a remarkable improvement on electrical conductivity was achieved. The thermoelectric films show high mechanical durability with only a 13% decrease in performance after 5000 bending cycles (bending curvature 1/2 mm(-1)). The overall performance of the n-type thermoelectric films approaches the values required for efficient flexible thermoelectric power generators. (C) 2015 Elsevier Ltd. All rights reserved