Effect of Freeze-Thaw Cycle on Shear Strength of Lime-Solidified Dispersion Soils

The freeze-thaw cycle of saline soil in the seasonal frozen area will produce diseases such as frost heave and thaw settlement, road frost boiling, collapse and uneven settlement. In order to reduce the occurrence of these undesirable phenomena, it is often necessary to improve the saline soil in engineering. In this paper, the typical carbonate saline soil in the west of Jilin Province, China is taken as the research object. By adding different content of lime (0%, 3%, 6%, 9%, 12%, 15%), the change of mechanical strength of lime solidified saline soil under different freeze-thaw cycles (0, 1, 3, 6, 10, 30, 60 times) is studied. The mechanical analysis is carried out by combining particle size analysis test and SEM image. The test results show that although repeated freeze-thaw cycles make the soil structure loose and the mechanical strength greatly reduced, the soil particles agglomerate obviously after adding lime, its dispersion is restrained by the flocculation of clay colloid, and the shear strength of soil is improved by the increase of the cohesive force between clay particles, and the optimal lime mixing ratio of the saline soil in this area is 9%

Exploring the electrochromic properties of poly(thieno[3,2-b]thiophene)s decorated with electron-deficient side groups

Two novel thieno[ 3,2-b] thiophene (TT)/3,4-ethylenedioxythiophene (EDOT)-based compounds of 2,5( EDOT-TT-EDOT) type bearing electron-withdrawing side groups (4-cyanophenyl or 4-pyridyl) at 3,6-positions of the TT moiety have been synthesized. Their electropolymerization leads to electroactive conjugated polymers, P(CNPh-ETTE) and P(Py-ETTE), which possess electrochromic properties changing the color from purple to pale grey-blue or from sand brown to pale grey-green, respectively. Cyclic voltammetry and spectroelectrochemical experiments reveal that functionalization with electron-withdrawing side groups decreases the HOMO and LUMO energy levels and contracts the band gap of materials. Both new polymers demonstrated extremely short response times of 0.9-1.1 s for bleaching and 0.34-0.35 s for coloring. P(CNPh-ETTE) and P(Py-ETTE) polymers showed reasonably good contrast (16-23%) and coloration efficiency (120-190 cm(2) C-1) in the visible region (at the maxima of their pi-pi* transitions, 540/570 nm), and high contrast and coloration efficiency in the near-infrared region (50-62% and 324-440 cm(2) C-1 at 1500 nm, respectively). While the stability of the pyridine-functionalized polymer, P(Py-ETTE), was shown to be low (with unstable charge-discharge characteristics, presumably due to the protonation of the pyridine ring during the redox process), P(CNPh-ETTE) demonstrated superior electrochromic performance retaining 91-96% of its electroactivity after 2000 cycles between -0.5 and +1.0 V. DFT calculations on these and related EDOT-TT-EDOT polymers reported by us early have been presented and analyzed to understand the structure-property relationships in this class of electrochromic polymers.Shenzhen Key Laboratory of Organic Optoelectromagnetic FunctionalMaterials of Shenzhen Science and Technology Plan [ZDSYS20140509094114164]; Shenzhen Peacock Program [KQTD2014062714543296]; Shenzhen Science and Technology Research Grant [JCYJ20140509093817690, JCYJ20160331095335232]; Nanshan Innovation Agency Grant [KC2015ZDYF0016A]; Guangdong Key Research Project [2014B090914003, 2015B090914002]; Guangdong Talents Project; National Basic Research Program of China (973 Program) [2015CB856505]; Natural Science Foundation of Guangdong Province [2014A030313800]; Guangdong Academician Workstation [2013B090400016]SCI(E)ARTICLE4769-784

Characteristics, causes, and prevention measures of coal mine water hazard accidents in China

As one of the top “five major hazards” in coal mines, water hazards have become the second leading cause of danger for coal mine safety and worker lives, next only to gas accidents. Between 2000 and 2022, a total of 1206 water hazard accidents occurred in coal mines in China, resulting in 5018 deaths, among which 103 larger-scale events resulted in 2039 deaths. In order to identify accident patterns, summarize lessons learned, and promote prevention of water hazard accidents, various aspects were analyzed statistically, including geographical regions, years, seasons, hydrogeological types, water sources, and ownership of coal mines. Analyses revealed that the complexity of hydrogeological conditions highly correlated with the frequency of water-related accidents. Southern China recorded the highest number of incidents and casualties, and the peak incidence periods throughout the year mainly concentrated in March to May and July to August. Goaf water was identified as the primary source of water filling, which presented strong concealment and harm, mainly occurring in township-owned coal mines with weaker technical exploration and management capabilities. As for the causes of accidents, complex mining environments and insufficient attention subjectively, i.e., improper management and illegal mining, were the main reasons for accidents. Hidden water-bearing structures such as point-like collapse columns and linear fault structures, as well as goaf water that were not explored and placed in accordance with regulations, were identified as the main technical causes of accidents. By analyzing bibliometrics, it was found that current research themes focusing on coal mine water disasters align well with the principles of “predicting and forecasting, exploring if in doubt, exploring before mining, treating before mining”. To address the problems of “unclear risk assessment, inaccurate risk identification, and incapability to cope with accidents” in coal mine water disasters, corresponding countermeasures were proposed in three aspects: surveying filling factors and hidden geological factors causing disasters, analyzing three-dimensional hydrogeological conditions of filling water, and implementing an accurate classification source prevention. In response to the trend of informationization and intelligent development of water disaster prevention and control, technical measures such as transparent mines, water disaster monitoring and early warning, and emergency rescue were proposed

Molecular engineering tuning optoelectronic properties of thieno[3,2-b]thiophenes-based electrochromic polymers

Thieno[3,2-b]thiophene (TT) monomers end-capped with 3,4-ethylenedioxythiophene (EDOT) moieties are electropolymerized to form pi-conjugated polymers with distinct electrochromic (EC) properties. Steric and electronic factors (electron donor and acceptor substituents) in the side groups of the TT core, as well as the structure of the polymer backbone strongly affect the electrochemical and optical properties of the polymers and their electrochromic characteristics. The studied polymers show low oxidation potentials, tunable from-0.78 to +0.30 V (vs. Fc/Fc(+)) and the band gaps from 1.46 to 1.92 eV and demonstrate wide variety of color palettes in polymer films in different states, finely tunable by structural variations in the polymer backbone and the side chains. EC materials of different colors in their doped/dedoped states have been developed (violet, deep blue, light blue, green, brown, purple-red, pinkish-red, orange-red, light gray, cyan and colorless transparent). High optical contrast (up to 79%), short response time (0.57-0.80 s), good cycling stability (up to 91% at 2000 cycles) and high coloration efficiency (up to 234.6 cm(2) C-1) have been demonstrated and the influence of different factors on the above parameters of EC polymers have been discussed.Shenzhen Key Laboratory of Organic Optoelectromagnetic Functional Materials of Shenzhen Science and Technology Plan [ZDSYS20140509094114164]; Shenzhen Peacock Program [KQTD2014062714543296]; Shenzhen Science and Technology Research Grant [JCYJ20140509093817690]; Nanshan Innovation Agency Grant [KC2015ZDYF0016A]; Guangdong Key Research Project [2014B090914003, 2015B090914002]; Guangdong Talents Project; National Basic Research Program of China [2015CB856505]; National Natural Science Foundation of China [51373075]; Guangdong Academician Workstation [2013B090400016]; Natural Science Foundation of Guangdong Province [2014A030313800]; Santander Universities Research Mobility AwardSCI(E)中国科学引文数据库(CSCD)ARTICLE163-766

Efficient and Eco-Friendly Preparation of 4-Methyl-5-formyl-thiazole

4-Methyl-5-formylthiazole, an intermediate for synthesizing cefditoren pivoxil,was prepared in good yield by Pd/BaSO4 catalyzed hydrogenation of 4-methylthiazole-5-carboxylic acid chloride. Detailed reaction conditions have been studied

New insights into the use of Neolithic pottery in Guangxi of South China: organic residue analysis of experimental and archaeological pottery

Abstract As one of the world’s earliest pottery origins in Eurasia, the role of pottery during Neolithic period in South China remains unclear. Here, we present a new understanding on the utilization pattern of early pottery from the Neolithic sites of Dayan, Dingsishan and Zengpiyan in Guangxi province, China. Compound-specific stable isotope analysis of pottery and bone lipids show that a persistent use of terrestrial C3 and C4 resources throughout the pottery utilization history highlight the culinary practice and terrestrial exploitation during Neolithic period. Contrary to the traditional view that the primary use of these pottery was closely linked with aquatic resource processing, no aquatic biomarkers were found in the potsherds, yet these compounds were detected in the cooking experiments in this study, indicating that aquatic resources in these sites were probably processed or consumed in other ways. Moreover, a remarkable diachronic change from extensive use of C3 and C4 resources to the intensive use of certain kinds of C3 resources in different Neolithic stages, further indicating that an ecological tradition rooted in the subtropical and tropical environments as well as the Neolithic social evolution exerted great influence upon the initial production and the subsequent utilization of early pottery in prehistoric South China

A feasible strategy for the fabrication of camouflage electrochromic fabric and unconventional devices

Research aimed at developing a wearable electrochromic fabric providing active camouflage has been ongoing for many years. Despite recent progress, no architecture has been shown to be suitable for practical applications, due to some major problems at the device level. The complicated structure of these prototype devices and their complex electrode materials reduce their practicability and make it difficult to achieve the aim of chameleon-like camouflage capabilities. Here, we use a laterally-configured electrode structure and inexpensive and commercially available ITO film as electrodes to construct an electrochromic (EC) fabric via an all-solution process. This novel EC fabric exhibits camouflage EC performance by changing colour between vegetable-green and soil-brown; it is also practical for camouflage applications due to its excellent flexibility and stability as well as being thin and lightweight. Moreover, this strategy can also be used to fabricate flexible transparent EC devices on plastics and “chameleon camouflage” on human skin. This approach is simple to configure and easy to operate, and has potential for the development of EC device systems that can change colour in camouflage applications. Keywords: Electrochromic, Fabric, ITO, Laterally configured, Camouflag