Preparation of Expanded Graphite and Graphite Nanosheets for Improving Electrical Conductivity of Polyester Coating Films

Expanded graphite and graphite nanosheets were facilely prepared by the thermal expansion of expandable graphite at 800 °C and sand milling of expanded graphite in water, respectively. When the expandable graphite precursor was prepared by the oxidation and intercalation of natural graphite (5 g) using KMnO4 (6 g) as an oxidant in a concentrated sulfuric acid solution (120 mL) at room temperature (25 °C) for 8 h, the expanded graphite with a maximum volumetric rate of 317 mL g−1 was prepared after the thermal expansion of the expandable graphite precursor at 800 °C for 60 s. The oxidation extent of natural graphite with KMnO4 is crucial for the preparation of expanded graphite. The thicknesses of graphite nanosheets decreased from 8.9 to 3.2 nm when the sand milling time of the expanded graphite in deionized water was prolonged from 6 to 24 h. The prolonging of the sand milling time not only decreased the layer number of the graphite nanosheet but also increased the d002 spacing due to the shocking and shearing forces. The addition of the expanded graphite powder and graphite nanosheets in a polyester paint efficiently improved the electrical conductivity of the resultant polyester coating films.

A novel strain of Stenotrophomonas acidaminiphila produces super-active alkaline protease during cassava effluent fermentation: process optimization, kinetic modeling and scale-up

Microbial fermentations for value-added metabolites production are exploited for efficient bioconversion of agro-industrial wastes for the dual purposes of pollution abatement and cost-effectiveness. In the present study, the regular 2-level factorial design was employed to screen fermentation parameters that enhance production of a novel alkaline protease by a strain of Stenotrophomonas acidaminiphila using cassava processing effluent as substrate. Data from randomized experiments of central composite rotatable design for improved enzyme activity, guided by path of steepest ascent experiments, were modeled and optimized by response surface methodology (RSM). Shake flask kinetics of production under optimized conditions was modeled by logistic and modified Gompertz models and determinations of maximum specific growth rate, µmax, maximum volumetric rate of substrate consumption, rsm, maximum volumetric rate of biomass formation, rxm and specific yield of product, Yp/x were made. Logistic model poorly fitted RSM-generated product formation and substrate consumption data. However, biomass formation was accurately fitted (adjusted r2 >99%), with µmax of 0.471 h-1. The modified Gompertz model, on the contrary, more accurately fitted all three major response data with minimal mean squared error. Potential for scale-up of bioprocess evaluated in 5-L bioreactor satisfactorily revealed 8.5-fold more substrate consumption in bioreactor than in shake flask. The 86.76-fold aqueous two-phase system-purified protease had a specific activity of 1416.73 Umg-1 which improved with increasing surfactant concentration. These results suggest significant bioprocess potential for sustainable cassava effluent management and concomitant commercial production of alkaline protease for industrial detergent application.

A Novel Strain of Stenotrophomonas Acidaminiphila Produces Super-active Alkaline Protease During Cassava Effluent Fermentation: Process Optimization, Kinetic Modeling and Scale-up

PurposeMicrobial fermentations for value-added metabolites production are exploited for efficient bioconversion of agro-industrial wastes for the dual purposes of pollution abatement and cost-effectiveness.MethodsIn the present study, the regular 2-level factorial design was employed to screen fermentation parameters that enhance production of a novel alkaline protease by a strain of Stenotrophomonas acidaminiphila using cassava processing effluent as substrate. Data from randomized experiments of central composite rotatable design for improved enzyme activity, guided by path of steepest ascent experiments, were modeled and optimized by response surface methodology (RSM). Shake flask kinetics of production under optimized conditions was modeled by logistic and modified Gompertz models and determinations of maximum specific growth rate, µmax, maximum volumetric rate of substrate consumption, rsm, maximum volumetric rate of biomass formation, rxm and specific yield of product, Yp/x were made.ResultsLogistic model poorly fitted RSM-generated product formation and substrate consumption data. However, biomass formation was accurately fitted (adjusted r2 >99%), with µmax of 0.471 h-1. The modified Gompertz model, on the contrary, more accurately fitted all three major response data with minimal mean squared error. Potential for scale-up of bioprocess evaluated in 5-L bioreactor satisfactorily revealed 8.5-fold more substrate consumption in bioreactor than in shake flask. The 86.76-fold aqueous two-phase system-purified protease had a specific activity of 1416.73 Umg-1 which improved with increasing surfactant concentration.ConclusionThese results suggest significant bioprocess potential for sustainable cassava effluent management and concomitant commercial production of alkaline protease for industrial detergent application.

Enhanced Oil Recovery Improvement Using Augmented Waterflooding to Induce Fluids Flow Orientation in a Reservoir

The objective is to design a control agent that will induce fluids flow orientation in a reservoir. The specific objectives are to delineate the minimum volumetric rate of the injecting fluid that will orient and control reservoir fluids flow rate and the recovery efficiency. Next estimate the maximum flooding injection rate for high oil recovery and finally predict reservoir fluids recovery efficiency. This work estimates the minimum volumetric rate of the injecting displacing fluid that will displace and control reservoir fluids flow rate and efficiency using mobility ratio. Next it estimates the maximum injection rate of the displacing agent that will recover high oil using summation of the reservoir thickness. Finally, it predicts reservoir fluids flow rates and cumulative oil recovery using unit floodable pore volume and the daily or yearly floodable volume. A cash flow model is used here to describe and compare the revenue (Recovery bill) and the costs (Capex and Opex). The result shows that it is possible to attain a floodable volumetric sweep efficiency of 70% with a corresponding recovery factor of 66% and a floodable volumetric sweep efficiency of 80 with a corresponding recovery factor of 72%, compared to scenario - C(Oil reservoir producing under water-drive and gas injection) where recovery factor is possibly 25 to 40%. Both recovery efficiency/factor depend on the summation of the volumetric floodable ratio. The novelty in this work is the development of a control agent which can increase recovery factor from 40% to 66% or 72%

Mechanistic Model and Optimization of the Diclofenac Degradation Kinetic for Ozonation Processes Intensification

This work focused on estimating the rate constants for three ozone-based processes applied in the degradation of diclofenac. The ozonation (Oz) and its intensification with catalysis (COz) and photocatalysis (PCOz) were studied. Three mathematical models were evaluated with a genetic algorithm (GA) to find the optimal values for the kinetics constants. The Theil inequality coefficient (TIC) worked as a criterion to assess the models’ deviation. The diclofenac consumption followed a slow kinetic regime according to the Hatta number (Ha<0.3). However, it strongly contrasted with earlier studies. The obtained values for the volumetric rate of photon absorption (VRPA) corresponding to the PCOz process (1.75×10−6 & 6.54×10−7 Einstein L−1 min−1) were significantly distant from the maximum (2.59×10−5 Einstein L−1 min−1). The computed profiles of chemical species proved that no significant amount of hydroxyl radicals was produced in the Oz, whereas the PCOz achieved the highest production rate. According to this, titanium dioxide significantly contributed to ozone decomposition, especially at low ozone doses. Although the models’ prediction described a good agreement with the experimental data (TIC<0.3), the optimization algorithm was likely to have masked the rate constants as they had highly deviated from already reported values.

Using A Novel Continuous Bioreactor In Enhancing The Biogas Production

Background: Since fossil fuels are limited and their burning is considered the main reason for environmental pollution, thinkers in the energy section are looking for a substitute for them. They have considered biogas as a potent replacement. Constant composition and volumetric rate, are ones of the challenges faced in term of using biogas. Therefore, in this study, a novel easily portable continuous bioreactor was designed and constructed to produce biogas at constant composition and volumetric rate, which is suitable for human uses. Sugar beet waste and anaerobic sludge were used as substrate and inoculum with an S/I ratio of 0.5 to 1, to produce biogas. Four parameters, i.e., hydraulic retention time (HRT), pH, biogas volume, and methane composition, were measured and compared.Results: The results of the mentioned reactor were compared with those of batch ones. The measurement revealed that the continuous reactor had a good performance on biogas purity and volumetric rate. The biogas contained about 53% methane. The suitable and preferable HRT and organic loading rate (OLR) were 18 days and 34.86 g VS/day. After the 18th day of operation, the biogas production process inside the continuous reactor was stable reaching about 411.2 ml STD/g VS per day.Conclusions: The reactor designed makes the biogas production process more manageable. Besides the production of the cumulative volume of biogas and constant methane percentage was achieved. As a result, the biogas produced is consumed daily, and a certain amount of gas is available every day. Since the percentage of gas produced is constant, it is possible to adjust the gas appliances with this amount of methane.

Comprehensive Kinetics of the Photocatalytic Degradation of Emerging Pollutants in a LED-Assisted Photoreactor. S-Metolachlor as Case Study

Although the potential and beneficial characteristics of photocatalysis in the degradation of a good number of emerging pollutants have been widely studied and demonstrated, process design and scale-up are restrained by the lack of comprehensive models that correctly describe the performance of photocatalytic reactors. Together with the kinetics of degradation reactions, the distribution of the radiation field in heterogeneous photocatalytic systems is essential to the optimum design of the technology. Both the Local Volumetric Rate of Photon Absorption (LVRPA) and the Overall Volumetric Rate of Photon Absorption (OVRPA) help to understand this purpose. This work develops a Six-Flux radiation absorption–scattering model coupled to the Henyey–Greenstein scattering phase function to evaluate the LVRPA profile in a LED-assisted photocatalytic reactor. Moreover, the OVRPA has been calculated and integrated into the kinetic equation, accounting for the influence of the radiation distribution on the reaction rate. The model has been validated with experimental data for the degradation of S-Metolachlor (MTLC), and the set of operating variables that maximize the reactor performance, 0.5 g/L of TiO2 P25 and pH 3, has been determined.

From core collapse to superluminous: the rates of massive stellar explosions from the Palomar Transient Factory

ABSTRACT We present measurements of the local core-collapse supernova (CCSN) rate using SN discoveries from the Palomar Transient Factory (PTF). We use a Monte Carlo simulation of hundreds of millions of SN light-curve realizations coupled with the detailed PTF survey detection efficiencies to forward model the SN rates in PTF. Using a sample of 86 CCSNe, including 26 stripped-envelope SNe (SESNe), we show that the overall CCSN volumetric rate is $r^\mathrm{CC}_v=9.10_{-1.27}^{+1.56}\times 10^{-5}\, \text{SNe yr}^{-1}\, \text{Mpc}^{-3}\, h_{70}^{3}$ at 〈z〉 = 0.028, and the SESN volumetric rate is $r^\mathrm{SE}_v=2.41_{-0.64}^{+0.81}\times 10^{-5}\, \text{SNe yr}^{-1}\, \text{Mpc}^{-3}\, h_{70}^{3}$. We further measure a volumetric rate for hydrogen-free superluminous SNe (SLSNe-I) using eight events at z ≤ 0.2 of $r^\mathrm{SLSN-I}_v=35_{-13}^{+25}\, \text{SNe yr}^{-1}\text{Gpc}^{-3}\, h_{70}^{3}$, which represents the most precise SLSN-I rate measurement to date. Using a simple cosmic star formation history to adjust these volumetric rate measurements to the same redshift, we measure a local ratio of SLSN-I to SESN of ${\sim}1/810^{+1500}_{-94}$, and of SLSN-I to all CCSN types of ${\sim}1/3500^{+2800}_{-720}$. However, using host galaxy stellar mass as a proxy for metallicity, we also show that this ratio is strongly metallicity dependent: in low-mass (logM* &lt; 9.5 M⊙) galaxies, which are the only environments that host SLSN-I in our sample, we measure an SLSN-I to SESN fraction of $1/300^{+380}_{-170}$ and $1/1700^{+1800}_{-720}$ for all CCSN. We further investigate the SN rates a function of host galaxy stellar mass, and show that the specific rates of all CCSNe decrease with increasing stellar mass.

Evaluation and Modelling of a Low Budget Hall Effect Based Flow-Rate Sensor using Adaptive Calibration Paradigm

The research work demonstrated the use of adaptative and comparative paradigm to calibrate and validate Hall Effect flowrate sensor’s related performance data. The experimental testbed used for the research work is composed of an IoT based platform integrated into a water pipe network. The use of IoT largely assisted in facilitating a well-coordinated and flexible paradigm for efficient data collections and analysis. Correlated and Associative analysis on data obtained shows a strong significant relationship (R2=89%) between the rate of Pulse count and rate of change in differential volume leading to the derivation of a model that is helpful in determining of volumetric rate and quantity of liquid dispense as function of pulse count generated from a Hall Effect flowrate sensor.

Criteria for differential diagnostics of the bronchopulmonary pathology in employees exposed to occupational air pollutants

Introduction. In recent years the nature of the developing professional pathology of the respiratory system and the features of clinical manifestations have been proved to be determined not only by harmful factors of the working environment but also by individual characteristics of the body, such as age, state of the immune system, etc. In some cases, the differential diagnosis of various forms of bronchopulmonary pathology to date causes certain difficulties.Aim. To establish the criteria for differential diagnosis of the nosological form of the pathology of the bronchopulmonary system from the effects of occupational airborne pollutants using fluorine compounds as an example at different times of diagnosis.Material and methods. 130 patients with an established diagnosis of occupational pathology of the broncho-pulmonary system were examined. All patients were divided into 2 groups: 1 - patients with professional bronchopulmonary pathology, in whom the disease was associated with the occupation during initial hospitalization, during the continuation of work in aluminum production or no later than a year after termination of work); Group 2 - persons with occupational bronchopulmonary pathology, who were diagnosed with respiratory pathology during the period of work, and the connection of the disease with the occupation more than 1 year after termination of work. Patients underwent spirometry, body plethysmography, a 6-minute walk test, questionnaires using the COPD Assessment Test (CAT) questionnaire, and respiratory symptoms were assessed using a 4-point mMRS scale. Statistical analysis methods were performed using the STATISTICA software package - version 6 of Stat Soft Inc. (USA). Intergroup comparison of quantitative indices was carried out using the nonparametric Mann-Whitney test. Values are presented as mean and mean error. To establish the criteria for differential diagnosis, a discriminant analysis was performed.Results. The CAT score (strong COPD influence on the patient’s life) was statistically significantly worse (25.91 points) in group 2 (versus 21.85 points in group 1), as well as spirometry indices: FVC, 68.30% of due values against 79.90% and FEV1 - 62.15% against 70.88%. (p &lt;0.05). As a result of discriminant analyzes, informative criteria for the differential diagnosis of occupational bronchopulmonary pathology were established: the severity of shortness of breath on the CAT questionnaire, the total score on the CAT questionnaire; the ratio of the forced vital capacity of the lungs to the forced expiratory volume in 1 minute (FVC /FEV1), the instantaneous volumetric rate after expiration is 25% FVC (MOS25), the instantaneous volumetric rate after expiration is 50% FVC (MOS50, forced expiratory volume per 1 minute (FEV1); total bronchial resistance according to body plethysmography (sRtotal), residual lung volume according to body plethysmography (RLV). The results indicate the progression of clinical manifestations of bronchopulmonary pathology even after stopping work in aluminum new production.Conclusion. The criteria for differential diagnosis of bronchopulmonary pathology from the effects of occupational airborne pollutants taking into account the individual characteristics of the body are established.