The new movement towards green chemistry and renewable feedstocks makes microbial production of chemicals more competitive. Among the numerous chemicals, organic acids are more attractive targets for ...process development efforts in the renewable-based biorefinery industry. However, most of the production costs in microbial processes are higher than that in chemical processes, among which over 60% are generated by separation processes. Therefore, the research of separation and purification processes is important for a promising biorefinery industry. This review highlights the progress of recovery processes in the separation and purification of organic acids, including their advantages and disadvantages, current situation, and future prospects in terms of recovery yields and industrial application.
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•Propose a novel GPC-based method to assess the aging condition of SBS binder in RAP.•Find suitable chemical composition fingerprinting to estimate SBS binders’ properties.•Clarify ...the change mechanism of polymer and asphaltene in SBS binder due to aging.
As fossil energy sources gradually become depleted, the reclamation of recycled asphalt pavement (RAP) has received increasing attention. During the production process of recycled mixtures, the aging conditions of binders in RAP need to be measured prior to the mixing design process. The conventional method adopts chemical solvents, including trichloroethylene and toluene to extract and recovery binders in the RAP. And then measure the corresponding properties of RAP binders. However, the whole process is complicated and time-consuming, and the used chemical solvents are highly toxic and harmful to researcher’s health. Some scholars have proposed some methods to test the aging condition of asphalt binders in the RAP directly without extraction and recovery using the novel observation instruments. However, these methods are not suitable for modified asphalt. At present, modified asphalt has been often used in the road construction,especially for SBS modified asphalt. As such, the present study aims to introduce a novel approach to test the aging conditions of SBS modified binders in the mixtures avoiding the extraction and recovery process based on gel permeation chromatography (GPC). For this purpose, the molecular weight distribution as well as the physical properties of modified asphalt and binders in the mixtures at various aging degrees were first analyzed using GPC test. The polymer and asphaltene content of asphalt binders derived from GPC test were found correlation well with the aging degrees and properties of asphalt binders. Following this, several estimation models correlating the polymer and asphaltene content with penetration, viscosity and rutting factor were established. The robustness of established models were verified using laboratory-aged asphalt mixtures with three different SBS modifier contents and two kinds of on-site RAPs. The verification results showed that the properties in the mixture were reasonably estimated.
► We perform a multi-cycle recharge–recovery field experiment in a confined aquifer. ► We establish a numerical model via a reversed analysis on the experimental data. ► The piezometric heads ...declined significantly when the recharge ended. ► The efficiency of a multi-cycle recharge was higher than a concentrated one. ► The recharge interval was the best when the water level rose to 40% of the peak.
Shanghai is one of the cities suffering from land subsidence in China. Land subsidence has caused serious financial losses. Thus, artificial recharge measures have been adopted to compensate the drawdown in shallow, confined aquifers and thereby control land subsidence. In this study, a multi-cycle recharge–recovery field experiment was performed to investigate the response of a shallow, confined aquifer to artificial recharge through a well. In the experiment, a series of recharge–recovery cycles with different recharge volumes and durations, with and without artificial pressure, were performed. The water levels monitored in the recharge and observation wells indicated the response of the aquifer to the multi-cycle recharge–recovery process. Meanwhile, a finite-difference method (FDM) numerical model was established, and its parameters were obtained via a reversed numerical analysis on the experimental data. The responses of the shallow, confined aquifer to the multi-cycle recharge–recovery process were simulated in detail using the model. The calculation results showed that the water level dropped significantly when the recharge ended. Moreover, the efficiency of a multi-cycle recharge was found to be higher than that of a concentrated one under the same recharge volume and time. The relationship between recharge frequency and efficiency, expressed as H=0.29498f0.40163 and R2=0.97264, respectively, was obtained through the FDM numerical simulation. In the recharge intervals, the optimal recharge efficiency was achieved when the water level rose to 40% of the peak.
This qualitative study aimed to uncover the meaning of the trauma experiences and recovery process of North Korean refugees. Ten North Korean refugees were interviewed, and the data gathered was ...analyzed using Giorgi's descriptive phenomenological method. Results included 2 main categories, 4 subcategories, and 11 meaning units. Core themes were ‘trauma experiences during the escape’ and ‘trauma recovery process.’ Sub-themes were ‘life-or-death situations,’ ‘emotional and psychological distress during the escape,’ ‘enduring pain and progressing toward inner growth,’ ‘rebuilding a broken life through relational resources and support.’ Based on these findings, the implications of North Korean refugees’ trauma experience and recovery process are discussed.
The flexible high-voltage direct current (HVDC) power system develops quickly with the large-scale utilization of new energy and the increase of direct current (dc) loads in recent years. HVDC ...circuit breakers are very important components in the flexible HVDC power system. The mechanical HVDC circuit breaker including vacuum interrupters is a potential solution for HVDC interruption. After the current interruption, a transient interrupting voltage (TIV) generated from the interaction with the external circuit will be applied to the mechanical HVDC circuit breakers and might cause a failure interruption. However, there are still few studies about the influences of TIV on the postarc dielectric recovery process of mechanical HVDC circuit breakers. In this article, a circuit model based on the simplification of a 10-kV mechanical HVDC circuit breaker is developed for the purpose of studying the characteristics of TIV. Then the effects of the parallel snubber circuit on the TIV are discussed. Moreover, the influence of TIV on the postarc residual plasma dissipation process is simulated by a particle-in-cell (PIC) model. The results show that the TIV with a parallel snubber circuit has little effect on the whole dissipation time compared with that without a parallel snubber circuit. It should be noted that the microdissipation processes of the above two situations are different.
Dynamic mechanical relaxation is a fundamental tool to understand the mechanical and physical properties of viscoelastic materials like glasses. Mechanical spectroscopy shows that the high-entropy ...bulk metallic glass (La
30
Ce
30
Ni
10
Al
20
Co
10
) exhibits a distinct β-relaxation feature. In the present research, dynamic mechanical analysis and thermal creep were performed using this bulk metallic glass material at a temperature domain around the β relaxation. The components of total strain, including ideal elastic strain, anelastic strain, and viscous-plastic strain, were analyzed based on the model of shear transformation zones (STZs). The stochastic activation of STZ contributes to the anelastic strain. When the temperature or external stress is high enough or the timescale is long enough, the interaction between STZs induces viscous-plastic strain. When all the spectrum of STZs is activated, the quasi-steady-state creep is achieved.
The extractant has a great influence on the performance and economy of the Phenols Recovery processes for treating coal-gasification wastewater. Meanwhile, computer-aided screening techniques have ...been applied to discern candidate solvents from the molecular perspective. In this paper, mesityl oxide, as a novel extractant, is found with high phenols removal efficiency through quantum chemical calculations. To confirm that, the removal performance with three different solvents (diisopropyl ether (DIPE), methyl isobutyl ketone (MIBK) and mesityl oxide) are investigated and compared via multi-stage counter-current extraction experiments. The experimental results identified that the performance using mesityl oxide as solvent is better than that using DIPE and MIBK. The total phenols concentration can be reduced from more than 5000 mg/L to less than 250 mg/L. Then, Phenols Recovery process using mesityl oxide as solvent is developed and conceptual designed. In view of the better performance and lower cost, mesityl oxide is a very promising extractant for the removal of phenols.
•Computer-aided screening techniques was applied to discern extraction solvents.•Via experiments and calculations, mesityl oxide is a novel extractant for phenols.•Phenols Recovery process using mesityl oxide is conceptual designed.•Compared to common extractant, mesityl oxide has a better performance and lower cost.
Feeding variability appears extensively in phenol and ammonia recovery process of coal chemical plant, which has caused severe problems in effluent quality. This study is aim to take the feeding ...variability into consideration for process optimization and analysis of the phenol and ammonia recovery process, have been not studied in previous efforts. For this purpose, this study proposed an optimization and analysis strategy for phenol and ammonia recovery process with feeding variability which introduced clustering and nonlinear regression. Firstly, 56,245 datasets were collected and preprocessed. 27 scenarios were generated by k-means clustering based method to represent the feeding variability and from which 7 typical scenarios were identified. Then, process model and costing model was established through equilibrium-stage model of extractor and Aspen Plus. Steam consumption of solvent recovery tower was estimated more accurately by nonlinear regression via BAS-BPNN. The mean relative error with the industrial value was decreased to 3.9% from 47% of the above-mentioned process model. Finally, sensitivity analysis was conducted via Sobol’ method to pick decision operating variables for lower optimization computing cost. Based on these, deterministic optimization models were individually solved at seven typical scenarios via genetic algorithm, and scenarios-between contrastive analysis suggested that the feeding variability directly affected ideal process operational policy with the maximum cost gap of 571,648 US$/a between typical scenarios. Additionally, stochastic optimization was solved and the results showed that the expected costs were 2.31%, 3.17% and 9.04% larger than the deterministic model. Obviously, the increase in the process's robustness and decrease in the likelihood of process performance deterioration under feeding variability were at the expense of cost.
•The process optimization and analysis introduced feeding variability.•The steam consumption was modified by nonlinear regression with MRE of 3.9%.•Feeding variability directly affected the ideal operational policy of the system.•The stochastic optimization gave the higher optimal operating cost.
We hypothesized that fine finger motor functions are controlled by the ipsilesional hemisphere, and that gross motor functions are compensated for by the contralesional hemisphere after brain injury ...in humans. The purpose of this study was to compare finger movements before and after hemispherotomy that defunctionated the ipsilesional hemisphere for patients with hemispherical lesions.
We statistically compared Brunnstrom stage of the fingers, arm (upper extremity), and leg (lower extremity) before and after hemispherotomy. Inclusion criteria for this study were: 1) hemispherotomy for hemispherical epilepsy; 2) a ≥ 6-month history of hemiparesis; 3) post-operative follow-up ≥ 6 months; 4) complete freedom from seizures without aura; and 5) application of our protocol for hemispherotomy.
Among 36 patients who underwent multi-lobe disconnection surgeries, 8 patients (2 girls, 6 boys) met the study criteria. Mean age at surgery was 6.38 years (range, 2–12 years; median, 6 years; standard deviation, 3.5 years). Paresis of the fingers was significantly exacerbated (p = 0.011) compared to pre-operatively, whereas that of the upper limbs (p = 0.07) and lower limbs (p = 0.103) was not.
Finger movement functions tend to remain in the ipsilesional hemisphere after brain injury, whereas gross motor movement functions such as those of the arms and legs are compensated for by the contralesional hemisphere in humans.
