CARBOHYDRATE POLYMERS
·
2013
·
IF 3.479
Guozhi Fan,Min Wang,Chongjing Liao,Tao Fang,Jianfen Li,Ronghui Zhou
Cellulose was isolated from rice straw by pretreatment with dilute alkaline and acid solutions successively, and it was further transferred into cellulose acetate in the presence of acetic anhydride and phosphotungstic acid (H 3 PW 12 O 40 ·6H 2 O). The removal of hemicellulose and lignin was affected by the concentration of KOH and the immersion time in acetic acid solution, and 83 wt.% content of cellulose in the treated rice straw was obtained after pretreatment with 4% KOH and immersion in acetic acid for 5 h. Phosphotungstic acid was found to be an effective catalyst for the acetylation of the cellulose derived from rice straw. The degree of substitution (DS) values revealed a significant effect for the solubility of cellulose acetate, and the acetone-soluble cellulose acetate with DS values around 2.2 can be obtained by changing the amount of phosphotungstic acid and the time of acetylation. Both the structure of cellulose separated from rice straw and cellulose acetate were confirmed by FTIR and XRD.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
PLoS One
·
2016
·Vol. 11
·期 2
·e0150399
·
IF 3.057
Zhengwei Wang,Yufeng Qu,Shihao Dong,Ping Wen,Jianjun Li,Ken Tan,Randolf Menzel
In Southeast Asia the native honey bee species Apis cerana is often attacked by hornets ( Vespa velutina ), mainly in the period from April to November. During the co-evolution of these two species honey bees have developed several strategies to defend themselves such as learning the odors of hornets and releasing alarm components to inform other mates. However, so far little is known about whether and how honey bees modulate their olfactory learning in the presence of the hornet predator and alarm components of honey bee itself. In the present study, we test for associative olfactory learning of A . cerana in the presence of predator odors, the alarm pheromone component isopentyl acetate (IPA), or a floral odor (hexanal) as a control. The results show that bees can detect live hornet odors, that there is almost no association between the innately aversive hornet odor and the appetitive stimulus sucrose, and that IPA is less well associated with an appetitive stimulus when compared with a floral odor. In order to imitate natural conditions, e.g. when bees are foraging on flowers and a predator shows up, or alarm pheromone is released by a captured mate, we tested combinations of the hornet odor and floral odor, or IPA and floral odor. Both of these combinations led to reduced learning scores. This study aims to contribute to a better understanding of the prey-predator system between A . cerana and V . velutina .
研究领域:
昆虫学
·
行为生态学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2025
·
IF 8.5
Hui Zhang,Song Xu,Xinyu Zhang,Mengting Ma,Zhongquan Sui,Harold Corke
The multi-scale structure changes of five underutilized starches, including waxy proso millet (PMS) and amaranth (AS) starches, non-waxy foxtail millet (FMS), buckwheat (BS) and oat (OS) starches, were investigated after modification with acetic anhydride (0.0165 mol) and vinyl acetate (0.0165 mol). Five starches exhibited a higher proportion of short chains compared to waxy and normal maize starches. Degree of substitution (DS) of acetylated starches ranged 0.03 to 0.08. Vinyl acetate modified non-waxy starches showed higher DS values than waxy starches, while acetic anhydride modified waxy starches exhibited higher DS values than non-waxy starches. Vinyl acetate reduced relative crystallinity (RC) by 1.3 % in PMS, 5.7 % in FMS, and 12.5 % in OS, whereas acetic anhydride did not significantly decrease RC for AS, FMS, BS and OS. For the non-waxy starches, gelatinization enthalpies after vinyl acetate modification were 4–22 % lower than after acetic anhydride modification. Additionally, the increase in amorphous lamellae thickness (da) of PMS, AS, BS and OS was greater with vinyl acetate than acetic anhydride, indicating that vinyl acetate more effectively disrupted crystalline lamellae. Overall, the presence of amylose influenced DS of modified starches. However, change of supramolecular structure was independent of DS but dependent on the acetylation reagent.
研究领域:
食品科学
·
高分子化学
✓ 已验证
DOI
PubMed
高影响因子
CARBOHYDRATE POLYMERS
·
2014
·
IF 3.916
Guozhi Fan,Chongjing Liao,Tao Fang,Shanshan Luo,Guangsen Song
The acetylation of cellulose using sulfonated Amberlyst 15 as a new and reusable catalyst was investigated. Optimization of the acetylation process was carried out by variation in the amount of added catalyst, acetic acid, and acetic anhydride as well as the reaction conditions, which includes reaction time and reaction medium. Cellulose acetate, with a degree of substitution (DS) value of 2.38 and yield of 54.1%, was obtained under the optimized conditions and characterized using Fourier-transform infrared (FTIR) spectroscopy, thermogravimetric analysis–derivative thermogravimetry (TGA–DTG), and differential scanning calorimetry (DSC). The sulfonated polymer catalyst could be easily recovered by centrifugation after acetylation. Both the fresh and recovered catalysts were characterized by means of FTIR, TGA–DTG, DSC, and scanning electron microscopy (SEM), and the recovered catalyst could be successfully reused without further treatment. It was found that Amberlyst 15 possessed excellent catalytic stability, no significant changes in the DS values, and consistent yields of cellulose acetate observed over four reaction cycles.
研究领域:
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Chemical Engineering Journal Advances
·
2021
·
IF 0
Qing Liu,Jiayun Shi,Taishan Wang,Wenwen Dong,Weixing Li,Weihong Xing
Ester have important applications in medicine chemical industry, but esterification is a typical reversible reaction controlled by thermodynamic equilibrium. In the study, a new type of catalytic composite membrane (CCM) with SA-MoS 2 /PAN as separation layer was reported. By-product water was proposed by pervaporation membrane reactor to improve the conversion rate of acetic acid. In 10 wt% ethanol-water solution, the separation factor of the catalytic composite membrane is 145 and the flux is 547 g m −2 h −1 . Under the optimal condition, the acetic acid conversion rate reached 94.3%, which was 29% higher than that of batch reaction. The effects of single-layer catalytic membrane and double-layer catalytic membrane on acetic acid conversion rate were studied, which showed that the double-layer catalytic membrane had higher stability in esterification reaction.It is proved that high crosslinking degree can improve the stability of the membrane and reduce the conversion rate of acetic acid.
研究领域:
化学工程
·
材料科学
✓ 已验证
DOI
ACS Applied Materials & Interfaces
·
2018
·
IF 8.097
Aijaz Ahmed Babar,Dongyang Miao,Nadir Ali,Jing Zhao,Xianfeng Wang,Jianyong Yu,Bin Ding
Textiles with excellent moisture transport characteristics play key role in regulating comfort of the body, and use of color in textiles helps in developing aesthetically pleasing apparels. Herein, we report an aesthetically pleasing and breathable dual-layer cellulose acetate (CA) based nanofibrous membranes with exceptional directional moisture transport performance. The outer layer was synthesized by subjecting CA nanofibers to hydrolysis and reactive dyeing processes, which converted moderately hydrophobic CA nanofibers into uniformly colored superhydrophilic CA nanofibers with an excellent wettability. In addition to excellent wettability and superhydrophilic nature, dyed CA (DCA) nanofibers also offered high color yield and dye fixation as well as considerable colorfastness performance against washing and light, thus, were used as the outer layer. However, pristine CA nanofibers were chosen as the inner layer for their moderate hydrophobicity. The subsequent CA/DCA nanofiber membrane produced a high wettability gradient, which facilitated directional moisture transport from CA to DCA layers. The resultant dual-layer nanofiber membranes offered a high color yield of 16.33 with ∼82% dye fixation, excellent accumulative one-way transport capacity (919%), remarkable overall moisture management capacity (0.89), and reasonably high water vapor transport rate (12.11 kg d–1 m–2), suggesting them to be a potential substrate for fast sweat-release applications.
研究领域:
材料科学
·
纺织工程
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF CHEMICAL AND ENGINEERING DATA
·
2018
·
IF 2.196
Kai Fan,Feng Zhou,Changxu Chen,Ye Li,Weisong Li,Bo Xiao,Chunjian Xu
Isobaric vapor–liquid equilibria of tert-butanol + chlorobenzene and tert-butyl acetate + chlorobenzene binary systems and the tert-butanol + tert-butyl acetate + chlorobenzene ternary system at 101.33 kPa were measured using a circulation VLE still. The data of binary systems passed the thermodynamic consistency test of the Herington method and the Van Ness point test, and the experimental data of the ternary system also passed the Wisniak consistency test. These binary systems’ VLE data were fitted by the Wilson, nonrandom two-liquid (NRTL), and universal quasichemical (UNIQUAC) activity coefficient models with minor deviations. Furthermore, the obtained binary interaction parameters from the binary systems were used to predict the VLE behavior of the tert-butanol + tert-butyl acetate + chlorobenzene ternary system. The rmsd of vapor and the temperature between the experimental and predicted values for the ternary system were smaller than 0.0304 and 0.81K, respectively. The results indicated that the relative volatility between tert-butanol and tert-butyl acetate obviously increased when adding chlorobenzene as a solvent. Thus, chlorobenzene is a promising solvent for the separation of the tert-butanol and tert-butyl acetate mixture system by extractive distillation.
研究领域:
化学工程
·
热力学
✓ 已验证
产品关联
DOI
高影响因子
Catalysts
·
2023
·Vol. 13
·期 2
·450
·
IF 3.9
Muhammad Naeem Younis,Zhiheng Ren,Chunshan Li,Erqiang Wang,Jie Li
The advancing effects of various alkali and alkaline earth metals (inclusive of K, Ca, and Sr) modified Cu/SiO2catalysts, prepared with a modified precipitation-gel method, were investigated for the production of ethanol via hydrogenation of methyl acetate. Our results showed that Sr-doped catalysts exhibited the best and most consistent results during catalytic tests. A series of techniques, including X-ray diffraction technique, Raman spectroscopy, N2adsorption/desorption, N2O titration method, FTIR spectroscopy, and H2temperature, programmed desorption and reduction (TPD and TPR), and X-ray Photoelectron Spectroscopy, which was used to check the detailed characterization of Sr modification in the catalyst and its structural impacts on the properties of the catalyst. These results demonstrated that the addition of 5%Sr could strengthen the intrinsic stability of the catalyst by formulating the appropriate ratio of Cu+/(Cu0+ Cu+) to facilitate catalytic outcome improvement. The addition of 5%Sr-30%Cu/SiO2under the most favorable conditions, resulting in the peak conversion of MA (95%) and ethanol selectivity (96%), indicates its magnificent catalytic stabilizing effects. Furthermore, the best performing catalyst was compared and tested under various conditions (LHSV and temperatures) and a 300 h long life run.Keywords:hydrogenation;methyl acetate;ethanol;strontium
研究领域:
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING
·
2023
·
IF 8.7
Yuxin Zhang,Dingsheng Wu,Shiqin Liao,Dongsheng Chen,Alfred Mensah,Xue Guo,Pengfei Lv,Qufu Wei
Passive radiative thermal management has been recognized as one of the most promising energy-saving technologies to provide thermal comfortable environment. However, static function and complex production process limit its application. Herein, we propose a simple strategy to achieve the integration of radiative cooling, radiative heating, and active electro-thermal heating. It is worth stressing that the radiative cooling is only based on the self-reflective structure and self-emissive molecular property of cellulose acetate electrospun membrane. In cooling mode, the average temperature of Janus film outdoor is 9.4 °C lower than commercial cotton fabric. Meanwhile, radiative heating and active heating stem from the photothermal and electrothermal performance of MXene . In heating mode, the average temperature of Janus film is 40 °C higher than cotton fabric. Flipping the Janus film allows for dynamic thermal management. In short, the scalable and universal strategy paves the way for the development of dynamic thermal-regulating technology.
研究领域:
材料科学
·
能源技术
✓ 已验证
产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2024
·
IF 7.7
Xiao Yang,Hongyang Ma,Yi Chen,Shyam Venkateswaran,Benjamin S. Hsiao
Particulates and organic toxins, such as microplastics and dye molecules, are contaminants in industrial wastewater that must be purified due to environmental and sustainability concerns. Carboxylated cellulose acetate (CTA-COOH) nanofibrous membranes were fabricated using electrospinning followed by an innovative one-step surface hydrolysis/oxidation replacing the conventional two-step reactions. This approach offers a new pathway for the modification strategy of cellulose-based membranes. The CTA-COOH membrane was utilized for the removal of particulates and cationic dyes through filtration and adsorption, respectively. The filtration performance of the CTA-COOH nanofibrous membrane was carried out; high separation efficiency and low pressure drop were achieved, in addition to the high filtration selectivity against 0.6-μm and 0.8-μm nanoparticles . A cationic Bismarck Brown Y, was employed to challenge the adsorption capability of the CTA-COOH nanofibrous membrane, where the maximum adsorption capacity of the membrane for BBY was 158.73 mg/g. The self-standing CTA-COOH membrane could be used to conduct adsorption-desorption for 17 cycles with the regeneration rate as high as 97.0 %. The CTA-COOH nanofibrous membrane has excellent mechanical properties and was employed to manufacture a spiral wound adsorption cartridge, which exhibited remarkable separation efficiency in terms of treated water volume, which was 5.96 L, and retention rate, which was 100 %.
研究领域:
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ACS Omega
·
2020
·
IF 2.87
Jiaqi Cheng,Conghua Zhan,Jiahui Wu,Zhixiang Cui,Junhui Si,Qianting Wang,Xiangfang Peng,Lih-Sheng Turng
A new type of deacetylated cellulose acetate (DA)@polydopamine (PDA) composite nanofiber membrane was fabricated by electrospinning and surface modification. The membrane was applied as a highly efficient adsorbent for removing methylene blue (MB) from an aqueous solution. The morphology, surface chemistry, surface wettability, and effects of operating conditions on MB adsorption ability, as well as the equilibrium, kinetics, thermodynamics, and mechanism of adsorption, were systematically studied. The results demonstrated that a uniform PDA coating layer was successfully developed on the surface of DA nanofibers. The adsorption capacity of the DA@PDA nanofiber membrane reached up to 88.2 mg/g at a temperature of 25 °C and a pH of 6.5 after adsorption for 30 h, which is about 8.6 times higher than that of DA nanofibers. The experimental results showed that the adsorption behavior of DA@PDA composite nanofibers followed the Weber’s intraparticle diffusion model, pseudo-second-order model, and Langmuir isothermal model. A thermodynamic analysis indicated that endothermic, spontaneous, and physisorption processes occurred. Based on the experimental results, the adsorption mechanism of DA@PDA composite nanofibers was also demonstrated.
研究领域:
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF CHEMICAL AND ENGINEERING DATA
·
2023
·
IF 2.6
Feihu Li,Mengyuan Li,Jin Guo,Xiwei Hu,Jiaming Zhu,Qunsheng Li,Hongkang Zhao
N-Propanol (NPA) and n-propyl acetate (NPAC) can form an azeotrope under normal pressure, so their separation cannot be carried out by conventional distillation. Therefore, 1-butyl-3-methylimidazole acetate ([BMIM][OAC]) and ethylene glycol (EG) were selected as entrainers for extractive distillation of the two substances. Isobaric vapor–liquid equilibrium data were obtained by experiments of NPA + NPAC, NPA + NPAC + [BMIM][OAC], and NPA + NPAC + EG at normal pressure; the experimental results showed that the separation effect of [BMIM][OAC] is significantly better than that of EG. Finally, the data were fitted and correlated with the NRTL model. The ARD (average relative deviation) of NPA + NPAC, NPA + NPAC + [BMIM][OAC], and NPA + NPAC + EG is less than 5%, indicating that the NRTL model has good applicability to the vapor–liquid system.
研究领域:
化学工程
·
分离技术
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）