scholarly journals Microfibrillated Cellulose Grafted with Metacrylic Acid as a Modifier in Poly(3-hydroxybutyrate)

Polymers ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 3970
Author(s):  
Marius Stelian Popa ◽  
Adriana Nicoleta Frone ◽  
Ionut Cristian Radu ◽  
Paul Octavian Stanescu ◽  
Roxana Truşcă ◽  
...  
Keyword(s):  
Active Sites ◽  
High Efficiency ◽  
Microfibrillated Cellulose ◽  
New Method ◽  
Processing Temperature ◽  
Lower Efficiency ◽  
Chemical Route ◽  
Good Thermal Stability ◽  
Uniform Dispersion ◽  
The Fourier Transform

This work proposes a new method for obtaining poly(3-hydroxybutyrate) (PHB)/microfibrillated cellulose (MC) composites with more balanced properties intended for the substitution of petroleum-based polymers in packaging and engineering applications. To achieve this, the MC surface was adjusted by a new chemical route to enhance its compatibility with the PHB matrix: (i) creating active sites on the surface of MC with γ-methacryloxypropyltrimethoxysilane (SIMA) or vinyltriethoxysilane (SIV), followed by (ii) the graft polymerization of methacrylic acid (MA). The high efficiency of the SIMA-MA treatment and the lower efficiency in the case of SIV-MA were proven by the changes observed in the Fourier transform infrared FTIR spectra of celluloses. All modified celluloses and the PHB composites containing them showed good thermal stability close to the processing temperature of PHB. SIMA-modified celluloses acted as nucleating agents in PHB, increasing its crystallinity and favoring the formation of smaller spherulites. A uniform dispersion of SIMA-modified celluloses in PHB as a result of the good compatibility between the two phases was observed by scanning electron microscopy and many agglomerations of fibers in the composite with unmodified MC. The dual role of SIMA-MA treatment, as both compatibilizer and plasticizer, was pointed out by mechanical and rheological measurements. This new method to modify MC and obtain PHB/MC composites with more balanced stiffness–toughness properties could be a solution to the high brittleness and poor processability of PHB-based materials.

scholarly journals Solution-Processed Transparent Conducting Electrodes for Flexible Organic Solar Cells with 16.61% Efficiency

2021 ◽  
Vol 13 (1) ◽  
Author(s):  
Juanyong Wan ◽  
Yonggao Xia ◽  
Junfeng Fang ◽  
Zhiguo Zhang ◽  
Bingang Xu ◽  
...  
Keyword(s):  
Solar Cells ◽  
Work Function ◽  
Organic Solar Cells ◽  
High Performance ◽  
High Efficiency ◽  
Electrical Stability ◽  
Solution Processed ◽  
Good Thermal Stability ◽  
Transparent Conducting ◽  
High Flexibility

AbstractNonfullerene organic solar cells (OSCs) have achieved breakthrough with pushing the efficiency exceeding 17%. While this shed light on OSC commercialization, high-performance flexible OSCs should be pursued through solution manufacturing. Herein, we report a solution-processed flexible OSC based on a transparent conducting PEDOT:PSS anode doped with trifluoromethanesulfonic acid (CF3SO3H). Through a low-concentration and low-temperature CF3SO3H doping, the conducting polymer anodes exhibited a main sheet resistance of 35 Ω sq−1 (minimum value: 32 Ω sq−1), a raised work function (≈ 5.0 eV), a superior wettability, and a high electrical stability. The high work function minimized the energy level mismatch among the anodes, hole-transporting layers and electron-donors of the active layers, thereby leading to an enhanced carrier extraction. The solution-processed flexible OSCs yielded a record-high efficiency of 16.41% (maximum value: 16.61%). Besides, the flexible OSCs afforded the 1000 cyclic bending tests at the radius of 1.5 mm and the long-time thermal treatments at 85 °C, demonstrating a high flexibility and a good thermal stability.

scholarly journals Adsorption and Photocatalytic Reduction of Carbon Dioxide on TiO2

Catalysts ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 47
Author(s):  
Oleksandr Shtyka ◽  
Viktar Shatsila ◽  
Radoslaw Ciesielski ◽  
Adam Kedziora ◽  
Waldemar Maniukiewicz ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Active Sites ◽  
High Efficiency ◽  
Chemical Potential ◽  
Band Gap Energy ◽  
Electromagnetic Spectrum ◽  
Reaction Intermediates ◽  
Factors Affecting ◽  
Phase Reduction ◽  
Reduction Of Co2

The photocatalytic activity of TiO2 depends on numerous factors, such as the chemical potential of electrons, charge transport properties, band-gap energy, and concentration of surface-active sites. A lot of research has been dedicated to determining the properties that have the most significant influence on the photocatalytic activity of semiconductors. Here, we demonstrated that the activity of TiO2 in the gas-phase reduction of CO2 is governed mainly by the desorption rate of the reaction intermediates and final products. This indicates that the specific surface area of TiO2 and binding strength of reaction intermediates and products are the main factors affecting the photocatalytic activity of TiO2 in the investigated process. Additionally, it was shown that rutile exhibits higher photocatalytic activity than anatase/rutile mixtures mainly due to its high efficiency in the visible portion of the electromagnetic spectrum.

Design of high-efficiency Hybrid Power Amplifier with concurrent F&F−1 class operations for 5G application

Frequenz ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Meisam Tahmasbi ◽  
Farhad Razaghian ◽  
Sobhan Roshani
Keyword(s):  
Power Amplifier ◽  
High Efficiency ◽  
New Method ◽  
Power Added Efficiency ◽  
Hybrid Power ◽  
Novel Structure ◽  
Mode A

Abstract This paper presents a novel structure of Hybrid Power Amplifier (HPA) to operate in two arbitrary classes of operation at two desirable frequencies. The proposed HPA is designed in concurrent F&F−1 classes, simultaneously for 5G application. Presented HPA can solve the harmonics interference problem for concurrent F and F−1 classes and also for any arbitrary class of operation in desired frequencies. The designed HPA operates at 1.5 GHz frequency in the F class mode, while operates at 2.1 GHz frequency in the F−1 class mode. A new method is presented by using two diplexers to provide two paths for signal in different frequencies. Two parallel paths are used at the output of the HPA circuit, so the proposed HPA can operate at two classes. Two diplexers are used in the HPA to make proper isolation between the designed paths. In design of the proposed HPA, according to the utilized diplexers, the amplifier can operate between two arbitrary classes of operation at desired frequencies without any specific switch. The measured drain efficiency (DE) and power added efficiency (PAE) parameters are 57 and 51%, respectively at 2.1 GHz, while measured DE and PAE are 64 and 54%, respectively at 1.5 GHz.

scholarly journals Gene Transfer to the Desiccation-Tolerant CyanobacteriumChroococcidiopsis

2001 ◽  
Vol 183 (7) ◽  
pp. 2298-2305 ◽  
Author(s):  
Daniela Billi ◽  
E. Imre Friedmann ◽  
Richard F. Helm ◽  
Malcolm Potts
Keyword(s):  
High Efficiency ◽  
Genetic Manipulation ◽  
Recipient Cell ◽  
Conjugative Transfer ◽  
Lower Efficiency ◽  
Genetic Studies ◽  
Variable Regions ◽  
Multiple Cycles ◽  
Experimental Strain

ABSTRACT The coccoid cyanobacterium Chroococcidiopsisdominates microbial communities in the most extreme arid hot and cold deserts. These communities withstand constraints that result from multiple cycles of drying and wetting and/or prolonged desiccation, through mechanisms which remain poorly understood. Here we describe the first system for genetic manipulation ofChroococcidiopsis. Plasmids pDUCA7 and pRL489, based on the pDU1 replicon of Nostoc sp. strain PCC 7524, were transferred to different isolates of Chroococcidiopsisvia conjugation and electroporation. This report provides the first evidence that pDU1 replicons can be maintained in cyanobacteria other than Nostoc and Anabaena. Following conjugation, both plasmids replicated inChroococcidiopsis sp. strains 029, 057, and 123 but not in strains 171 and 584. Both plasmids were electroporated into strains 029 and 123 but not into strains 057, 171, and 584. Expression of P psbA-luxAB on pRL489 was visualized through in vivo luminescence. Efficiencies of conjugative transfer for pDUCA7 and pRL489 into Chroococcidiopsissp. strain 029 were approximately 10−2 and 10−4 transconjugants per recipient cell, respectively. Conjugative transfer occurred with a lower efficiency into strains 057 and 123. Electrotransformation efficiencies of about 10−4electrotransformants per recipient cell were achieved with strains 029 and 123, using either pDUCA7 or pRL489. Extracellular deoxyribonucleases were associated with each of the five strains. Phylogenetic analysis, based upon the V6 to V8 variable regions of 16S rRNA, suggests that desert strains 057, 123, 171, and 029 are distinct from the type species strain Chroococcidiopsis thermalis PCC 7203. The high efficiency of conjugative transfer of Chroococcidiopsis sp. strain 029, from the Negev Desert, Israel, makes this a suitable experimental strain for genetic studies on desiccation tolerance.

Multivariate Constrained GNSS Real-time Full Attitude Determination Based on Attitude Domain Search

2018 ◽  
Vol 72 (2) ◽  
pp. 483-502
Author(s):  
Hongtao Wu ◽  
Xiubin Zhao ◽  
Chunlei Pang ◽  
Liang Zhang ◽  
Bo Feng
Keyword(s):  
Objective Function ◽  
Success Rate ◽  
High Efficiency ◽  
Attitude Determination ◽  
A Priori ◽  
Three Dimensional ◽  
Satellite System ◽  
New Method ◽  
Lambda Method ◽  
Attitude Angle

A priori attitude information can improve the success rate and reliability of Global Navigation Satellite System (GNSS) multi-antennae attitude determination. However, a priori attitude information is nonlinear, and integrating a priori information into the objective function rigorously will increase the complexity of an ambiguity domain search, such as the Multivariate Constrained-Least-squares Ambiguity Decorrelation Adjustment (MC-LAMBDA) method. In this paper, a new method based on attitude domain search is presented to make use of the a priori attitude angle information with high efficiency. First, the a priori information of pitch and roll is integrated into the search process to derive the analytic search step for attitude angle, and the integer candidates are determined by traversal search in the three-dimensional attitude domain. Then, the objective function is parameterised with Euler angles, and a non-iterative approximate method is utilised to simplify the iterative computation in calculating objective function values. Experimental results reveal that compared to the MC-LAMBDA method, our new method has the same success rate and reliability, but higher efficiency in making use of a priori attitude information.

scholarly journals Heterogeneous Catalytic Synthesis of 2-Methylbenzimidazole from 2-Nitroaniline and Ethanol Over Mg Modified Cu-Pd/γ-Al2O3

Catalysts ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 8 ◽  
Author(s):  
Feng Feng ◽  
Yaqin Deng ◽  
Zheng Cheng ◽  
Xiaoliang Xu ◽  
Qunfeng Zhang ◽  
...  
Keyword(s):  
Active Sites ◽  
Hydrogen Transfer ◽  
High Efficiency ◽  
Simple Procedure ◽  
Direct Synthesis ◽  
Reaction System ◽  
Simple Method ◽  
Heterogeneous Catalytic ◽  
Coupled Reaction ◽  
Al2o3 Catalyst

The direct synthesis of benzimidazoles from 2-nitroaniline and ethanol over Cu-Pd/γ-Al2O3 catalysts has the advantages of requiring easily available starting materials, having high efficiency, and a simple procedure. The modification by Mg of the Cu-Pd/γ-Al2O3 catalyst could improve the catalytic activity significantly. The addition of Mg to the Cu-Pd/γ-Al2O3 catalyst could maintain and promote the formation of CuPd alloy active sites. Meanwhile, the basicity of the support was enhanced appropriately by Mg, which generated more basic sites (Al-Oδ−) to accelerate the dehydrogenation of alcohol and increased the rate of the whole coupled reaction. The 2-nitroaniline was completely converted over Cu-Pd/(Mg)γ-Al2O3 after reacting for six hours, and the yield of 2-methylbenzimidazole was 98.8%. The results of this work provide a simple method to develop a more efficient catalyst for the “alcohol-dehydrogenation, hydrogen transfer and hydrogenation” coupled reaction system.

Preparation, Characterization and UV Absorption of Phosphotungstic Acid Cerium

2014 ◽  
Vol 1061-1062 ◽  
pp. 328-332
Author(s):  
Hai Lian Yu ◽  
Zhen Hu
Keyword(s):  
Phosphotungstic Acid ◽  
Absorption Capacity ◽  
Uv Absorption ◽  
Precipitation Method ◽  
Gravimetric Analysis ◽  
X Ray ◽  
Good Thermal Stability ◽  
Infrared Spectrometer ◽  
The Fourier Transform ◽  
Fluorescence Spectrometer

Phosphotungstic acid cerium [CePW12O40] was prepared with phosphotungstic acid and hydrate cerium nitrate by precipitation method. The Fourier transform infrared spectrometer, X-ray diffractometer, X-ray fluorescence spectrometer and thermal gravimetric analysis were used to characterize product, The UV-VIS spectrophotometer was used to measure its absorption capacity. The results showed that the prepared product is CePW12O40, it has good crystal and good thermal stability, its purity reaches 99.55%, there is good UV absorption property between 200nm and 260nm..

The Group Keyword Management Method of the Heterogeneous WSN Based on Topology

2013 ◽  
Vol 798-799 ◽  
pp. 480-483
Author(s):  
Tao Ma ◽  
Juan Chen
Keyword(s):  
Wireless Sensor Network ◽  
Sensor Network ◽  
High Efficiency ◽  
New Method ◽  
Wireless Sensor ◽  
Batch Method ◽  
Heterogeneous Wireless Sensor Network ◽  
Management Method

The new method used the node to make up the keyword management tree. The keyword management tree was optimized with renewing the group keyword. In the meanwhile, the use of father nodes and the processing batch method improved the keyword renewing efficiency. The analysis result of theory shows that the method is a high efficiency and extendible group keyword management method which used in the heterogeneous wireless sensor network.

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