JOURNAL OF MATERIALS SCIENCE
·
2018
·Vol. 54
·期 7
·5331-5342
·
IF 2.993
Segovia Rubén,Ding Leyan,Jiang Hu,Miao Peng,Sun Xiudong,Shi Hongyan,Gao Bo
CH 3 NH 3 PbI 3 (MAPbI 3 ) exhibits distinctive properties for applications in photovoltaics, light emitting devices, photodetectors, and fuel cells. The working temperature of an optoelectronic device affects the photophysical properties of the active material, which is closely related to the device performance. In MAPbI 3 , these properties are intimately connected with its crystalline structure which is temperature dependent. Here, we study the photoluminescence (PL) behavior of MAPbI 3 microwires (MWs) under recursive tetragonal-to-cubic and cubic-to-tetragonal phase transitions induced by temperature cycles from 40 °C (tetragonal phase) to 80 °C (cubic phase). MWs emission exhibited an initial redshift in wavelength by increasing the temperature from the tetragonal to the cubic phase, but after several thermal cycles, this trend reversed and the emission blueshifted. In both phases independently, the emission blueshifted and became stronger with increasing the cycles. The results indicate a thermal cycling-dependent PL and a gradual crystalline structure deformation due to a reiterated change in the MWs lattice, which implies variation in the electronic bandgap along the heating–cooling process. The alteration of the electronic band structure was corroborated by thermal cycling-reflectance measurements. The awareness behavior of material properties upon phase transitions and temperature fluctuations is of great importance for the optimization of optoelectronic devices.
研究领域:
材料科学
·
光学
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING RESEARCH & DESIGN
·
2022
·
IF 4.119
Shengzhe Jia,Ye Gao,Zongqiu Li,Teng Zhang,Jian Liu,Jingkang Wang,Zhenguo Gao,Junbo Gong
This study explores the process intensification techniques and process control strategies on the product properties optimization. α-PABA, a long needle-like shape, can cause problems for the downstream processing. This study proposes ultrasound technique, supercooling control (SSC), and temperature cycling (TC) technologies to optimize the morphology and crystal size distribution of α-PABA. Firstly, the solubility and metastable zone of α-PABA in ethanol solvent are measured to determine the operational range. Next, the concentration calibration model is established to correlate the solubility with the ATR-FTIR intensity and temperature qualitatively. Furthermore, the process improvement techniques and control strategies are introduced to optimize the products. The ultrasound intensification contributes to produce the uniform crystal seeds. The SSC is benefit for the crystal growth, and can reduce the L/D ratio of the crystal product. While, TC is an efficient tool to eliminate the fine crystals. Moreover, the combination of ultrasound, SSC, and TC technology can show a significant improvement on the product particle aspects. The L/D ratio, crystal size, crystal morphology can show different degree of improvement under the combination techniques. At last, the outlook and perspectives on the process analytical technology are developed.
研究领域:
化学工程
·
过程控制
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING SCIENCE
·
2023
·
IF 4.7
Yaoguo Wang,Jie Sun,Weiwei Tang,Junbo Gong
Deracemization is a promising chiral resolution technique that combines racemization reaction with stereoselective crystallization for complete chiral symmetry breaking and has attracted much attention. However, the integration process of reaction-crystallization is rather complex and often requires long operation time with high initial solid enantiomer excess which greatly limits its wide application. Herein, we proposed a novel strategy that combines the use of both ultrasound and temperature cycles to accelerate the process of deracemization and thereby chiral separation. A chiral compound, N-acetyl- dl -leucine, was selected as a model drug for experimental validation. We found that either ultrasound or temperature cycle process was capable of accelerating the deracemization efficiency, nonetheless, the combination of the two methods leads to the antagonistic action, decreasing process efficiency and product chiral purity. Through the time-elapsed characterizations on enantiomeric purity of N-acetyl- l -leucine over the course of deracemization, we revealed that the ultrasound negatively impacted the process efficiency of chiral separation via promotion of primary heterogeneous nucleation during the cooling stage. Finally, we strategically designed a synergistic process intensification of crystallization-induced deracemization between temperature cycling and the periodic ultrasound that switches on only during the heating stage to achieve highly efficient separation of pure N-acetyl- l -leucine with theoretical 100% yield at extremely low initial solid ee %.
研究领域:
化学
·
药学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2022
·
IF 16.744
Xinglu Jiang,Kangjing Li,Beibei Xie,Jun Zhou
Taq DNA polymerase is the most widely used enzyme for PCR amplification and it contains 832 amino acids but no cysteines. Bovine serum albumin (BSA) is an 832-amino acid protein containing 35 cysteines, and at high temperature BSA can produce protein hydrogels through recombined disulfides and noncovalent bonds. When hydrogels are prepared using a mixture of Taq DNA polymerase and BSA, no disulfide bonds occur between them, and noncovalent bonds are the main forces holding together the Taq DNA polymerase with the hydrogels. During PCR amplification, temperature cycling can destroy the noncovalent bonds, thereby releasing Taq DNA polymerase from the hydrogels to synthesize DNA. The release rate, regulated through the variation of BSA concentration, allows for velocity-controlled amplification of DNA. As the amount of DNA products exceeds that of the Taq DNA polymerase released from hydrogels, a linear amplification replaces the exponential PCR amplification. When the amplification velocity begins to decrease, the time needed for reaching a plateau increase. This provides a broader detection window for the analysis of the end products, which correspond to the difference compared with the initial DNA concentration. The number of primers is continuously reduced with increasing cycles, which further causes a decline in the DNA amplification efficiency. The difference in the initial DNA template may cause a different consumption of primers, which can cause errors in the Ct values in the case of qPCR. Based on the slopes of the linear amplification curve, the Ct values can be calibrated to reduce this error, and a more accurate detection of the initial content of the target DNA can be implemented.
研究领域:
分子生物学
·
生物技术
·
生物化学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）