scholarly journals Ultimate pretreatment of lignocellulose in bioethanol production by combining both acidic and alkaline pretreatment

2019 ◽  
Vol 268 ◽  
pp. 03002 ◽  
Author(s):  
Dinh Quan Nguyen ◽  
Le Nhat Minh Nguyen ◽  
Thi Tuong An Tran ◽  
Hoai Nhan Cao ◽  
Thi Kim Phung Le ◽  
...  
Keyword(s):  
Waste Water ◽  
High Efficiency ◽  
Acidic Solution ◽  
Alkaline Pretreatment ◽  
Lignocellulosic Materials ◽  
Bioethanol Production ◽  
Saw Dust ◽  
Lignin Removal ◽  
High Basicity ◽  
Very High

Alkaline pretreatment has been known as the most popular method to process lignocellulosic materials for bioethanol production due to its simplicity and high efficiency. However, the waste water of the process has a very high basicity, which requires neutralization with acids upon further disposal. In this study, rubber wood saw dust (Hevea brasiliensis) was employed as lignocellulosic material and its pretreatment was inspected with both diluted H2SO4 and NaOH in different combination ways. Hereby, acid was used not only for waste water neutralization but also to contribute to lignin removal. Analysis results showed that an aqueous solution of 2.0 - 2.5 wt.% H2SO4 can be used to treat the biomass followed by alkaline pretreatment. By this so-called combo-pretreatment technique, cellulose was well preserved without significant hydrolysis while the final pretreatment efficiency was up to 63.0%, compared to 48.2% of using only the alkaline solution and 13.7% of using only the acidic solution. Finally, alkaline waste water can be mixed to be neutralized with acidic waste water from the two previous steps. This innovated technique improved the pretreatment efficiency almost without increasing in chemical cost.

scholarly journals Near quantitative synthesis of urea macrocycles enabled by bulky N-substituent

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yingfeng Yang ◽  
Hanze Ying ◽  
Zhixia Li ◽  
Jiang Wang ◽  
Yingying Chen ◽  
...  
Keyword(s):  
High Efficiency ◽  
Molecular Structures ◽  
High Yield ◽  
Kinetic Control ◽  
High Concentration ◽  
Weak Association ◽  
Quantitative Synthesis ◽  
Thermodynamic Stabilization ◽  
Discrete Structures ◽  
Very High

AbstractMacrocycles are unique molecular structures extensively used in the design of catalysts, therapeutics and supramolecular assemblies. Among all reactions reported to date, systems that can produce macrocycles in high yield under high reaction concentrations are rare. Here we report the use of dynamic hindered urea bond (HUB) for the construction of urea macrocycles with very high efficiency. Mixing of equal molar diisocyanate and hindered diamine leads to formation of macrocycles with discrete structures in nearly quantitative yields under high concentration of reactants. The bulky N-tert-butyl plays key roles to facilitate the formation of macrocycles, providing not only the kinetic control due to the formation of the cyclization-promoting cis C = O/tert-butyl conformation, but also possibly the thermodynamic stabilization of macrocycles with weak association interactions. The bulky N-tert-butyl can be readily removed by acid to eliminate the dynamicity of HUB and stabilize the macrocycle structures.

Design and Analysis of a High Pitch to Chord Ratio Cascade Representative of Ducted Propfans

1991 ◽  
Author(s):  
A. Weber ◽  
W. Steinert ◽  
H. Starken
Keyword(s):  
Boundary Layer ◽  
Mach Number ◽  
High Efficiency ◽  
Pressure Ratio ◽  
Flow Analysis ◽  
High Pitch ◽  
Integral Boundary ◽  
Pressure Loss Coefficient ◽  
Distribution Boundary ◽  
Very High

Efforts to reduce the specific fuel consumption of a modern aero engine focus in particular on increasing the by-pass ratio beyond the current level of around 5. One concept is the counterrotating shrouded propfan operating at low overall pressure ratio and having only very few fan blades of extremely high pitch/chord ratios. The relative inlet Mach numbers cover a range from 0.7 at the hub to 1.1 at the tip section of the first rotor. A propfan cascade was designed by taking into account two characteristic features of a propfan blade-blade section: • a very high pitch/chord ratio of s/c = 2.25 • an inlet Mach number of M1 = 0.90 which leads to transonic flow conditions inside the blade passage In the design process a profile generator and a quasi-3D Euler solver were used iteratively to optimize the profile Mach number distribution. Boundary layer behavior was checked with an integral boundary layer code. The cascade design was verified experimentally in the transonic cascade wind tunnel of DLR at Cologne. The extensive experimental results confirm the design goal of roughly 5 degree flow turning. A total pressure loss coefficient of less than 1.5% was measured at design conditions. This validates the very high efficiency level the propfan concept is calling for. A 2D Navier-Stokes flow analysis code yields good results in comparison to the experimental ones.

scholarly journals Instantaneous Electromagnetic Torque Components in Synchronous Motors Fed by Load-Commutated Inverters

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3223
Author(s):  
Gabriel Ekemb ◽  
Fouad Slaoui-Hasnaoui ◽  
Joseph Song-Manguelle ◽  
P. M. Lingom ◽  
Issouf Fofana
Keyword(s):  
High Efficiency ◽  
Air Gap ◽  
International Standards ◽  
Synchronous Motors ◽  
Gas Compression ◽  
Variable Frequency Drives ◽  
Torsional Analysis ◽  
Analytical Expressions ◽  
Very High ◽  
Excitation Circuit

This paper proposes time-domain analytical expressions of the instantaneous pulsating torque components in a synchronous machine air gap when supplied by a load-commutated-inverter (LCI) system. The LCI technology is one of the most used variable frequency drives when very high power and low speed are required in applications such as pipeline recompression and decompression, as well as liquefied natural gas compression. In such applications, synchronous motors are used because of their high efficiency resulting from a separated supply of the current to their rotor through the excitation circuit. These applications usually have long and flexible shafts, which are very sensitive to torsional vibration excitation when their natural frequencies interact with any external torque applied to the shaft. A torsional analysis is required by international standards to assess the survivability of the shaft through the overall speed range of the motor. Therefore, the magnitude and frequencies of the motor air-gap torque are needed for such evaluation. The proposed developments are supported by numerical simulations of LCI systems in a large range of operation range. From the simulation results, torque harmonic families are derived and expressed in a parametric form, which confirm the accuracy of the proposed relationships.

scholarly journals The use of the method of controlling the electrochemical parameters of aqueous solutions to combat complications in the operation of oil field pipelines

2021 ◽  
Vol 225 ◽  
pp. 01008
Author(s):  
Oleg Latypov ◽  
Sergey Cherepashkin ◽  
Dina Latypova
Keyword(s):  
Aqueous Solutions ◽  
Oil And Gas ◽  
High Efficiency ◽  
Oil Field ◽  
Oil Fields ◽  
Control Methods ◽  
Test Results ◽  
Chemical Reagents ◽  
Electrochemical Parameters ◽  
Very High

Corrosion of equipment in the oil and gas complex is a global problem, as it contributes to huge material costs and global disasters that violate the environment. Corrosion control methods used to protect equipment do not always ensure the absolute safety of the operation of oil and gas facilities. Moreover, they are quite expensive. The developed method for controlling the electrochemical parameters of aqueous solutions to combat complications during the operation of oil-field pipelines provides the necessary protection against corrosion. The method is economical and environmentally friendly, since it does not require the use of chemical reagents. The test results have shown a very high efficiency in dealing with complications in oil fields.

scholarly journals The Use of Hyaluronic Acid Combined with Teosyal Redensity II for the Treatment of Dark Circles Under the Eyes

2017 ◽  
Vol 54 (1) ◽  
pp. 37-40 ◽  
Author(s):  
Valeriu Ardeleanu ◽  
Sorin Ioan Berbece ◽  
Ioan Petre Florescu ◽  
Radu Cristian Jecan
Keyword(s):  
Hyaluronic Acid ◽  
High Efficiency ◽  
Cumulative Effects ◽  
Major Improvement ◽  
Safe Product ◽  
Very High

This study intends to highlight the results of the product Teosyal Redensity II through the cumulative effects of its constituents, that have an antioxidant, hydrating, filling and facial restructuring role. The study was performed in the Arestetic Clinic, Galai, between 07.12.2015 and 07.12.2016 on a group of 49 patients, of which 43 women and 6 men. Teosyal Redensity 2 proved to be a safe product - as long as it is injected correctly, it does not cause complications. It�s easy to inject and has a very high efficiency. It�s a periorbital rejuvenation and restructuring product, with a filling, antioxidant, hydration and dermal redensification effect. In the case of persons that needed a second injection after 1 month, one could observe a major improvement in elasticity and firmness felt by the person performing the injection. The injection requires small quantities of the substance and is accompanied by only mild discomfort. The result is visible right away.

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