Degradation and Toxicity Assay During Electrocatalysis of Chlorobenzene in Aqueous Solution

The degradation and toxicity assay on a three-dimensional electrocatalytic oxidation (ECO) of organic pollutants were described in this paper. Aqueous chlorobenzene (CB, 50 mg/L) was chosen as model pollutant and C. vulgaris was applied to assess the toxicity evolution during electrocatalytic oxidation for this study. The degradation and mineralization rate of CB, and the toxicity of wastewater sample during the electro-oxidation were determined meantime under suitable experimental conditions. The experimental results indicated that CB, oxidized incompletely to CO2 and H2O, was removed prior to total organic carbon (TOC), and the bio-toxicity was relevant to the intermediate products of CB degradation. The major intermediate products included phenol, biphenyl, 1,4-benzoquinone and other small molecular organic acids, unequivocally identified by GC/MS and IC. It was essential to maintain enough mineralization for toxicity reduction during electro-oxidation of organics in water.National Key Technologies Research & Development Program of China (No. 2011BAE07B09)||National Natural Science Foundation of China (No. 51278465

The in vivo study on the radiobiologic effect of prolonged delivery time to tumor control in C57BL mice implanted with Lewis lung cancer

<p>Abstract</p> <p>Background</p> <p>High-precision radiation therapy techniques such as IMRT or sterotactic radiosurgery, delivers more complex treatment fields than conventional techniques. The increased complexity causes longer dose delivery times for each fraction. The purpose of this work is to explore the radiobiologic effect of prolonged fraction delivery time on tumor response and survival in vivo.</p> <p>Methods</p> <p>1-cm-diameter Lewis lung cancer tumors growing in the legs of C57BL mice were used. To evaluate effect of dose delivery prolongation, 18 Gy was divided into different subfractions. 48 mice were randomized into 6 groups: the normal control group, the single fraction with 18 Gy group, the two subfractions with 30 min interval group, the seven subfractions with 5 min interval group, the two subfractions with 60 min interval group and the seven subfractions with 10 min interval group. The tumor growth tendency, the tumor growth delay and the mice survival time were analyzed.</p> <p>Results</p> <p>The tumor growth delay of groups with prolonged delivery time was shorter than the group with single fraction of 18 Gy (P < 0.05). The tumor grow delay of groups with prolonged delivery time 30 min was longer than that of groups with prolonged delivery time 60 min P < 0.05). There was no significant difference between groups with same delivery time (P > 0.05). Compared to the group with single fraction of 18 Gy, the groups with prolonged delivery time shorten the mice survival time while there was no significant difference between the groups with prolonged delivery time 30 min and the groups with prolonged delivery time 60 min.</p> <p>Conclusions</p> <p>The prolonged delivery time with same radiation dose shorten the tumor growth delay and survival time in the mice implanted with Lewis lung cancer. The anti-tumor effect decreased with elongation of the total interfractional time.</p

Tunable Interband Transitions in Twisted h-BN/Graphene Heterostructures

In twisted h-BN/graphene heterostructures, the complex electronic properties of the fast-traveling electron gas in graphene are usually considered to be fully revealed. However, the randomly twisted heterostructures may also have unexpected transition behaviors, which may influence the device performance. Here, we study the twist angle-dependent coupling effects of h-BN/graphene heterostructures using monochromatic electron energy loss spectroscopy. We find that the moir\'e potentials alter the band structure of graphene, resulting in a redshift of the intralayer transition at the M-point, which becomes more pronounced up to 0.25 eV with increasing twist angle. Furthermore, the twisting of the Brillouin zone of h-BN relative to the graphene M-point leads to tunable vertical transition energies in the range of 5.1-5.6 eV. Our findings indicate that twist-coupling effects of van der Waals heterostructures should be carefully considered in device fabrications, and the continuously tunable interband transitions through the twist angle can serve as a new degree of freedom to design optoelectrical devices

Evaluation of Proton Therapy Accuracy Using a PMMA Phantom and PET Prediction Module

Purpose: Positron emission tomography (PET) scanning is a widely used method of proton therapy verification. In this study, a proton radiotherapy accuracy verification process was developed by comparing predicted and measured PET data to verify the correctness of PET prediction and was tested at the Shanghai Proton and Heavy Ion Center.Method: Irradiation was performed on a polymethyl methacrylate (PMMA) phantom. There were two dose groups, to which 2 and 4 Gy doses were delivered, and each dose group had different designed dose depths ranging from 5 to 20 cm. The predicted PET results were obtained using a PET prediction calculation module. The measured data were collected with a PET/computed tomography device. The predicted and measured PET data were normalized to similar PET amplitude values before comparison and were compared using depth and lateral profiles for the position error. The error was evaluated at the position corresponding to 50% of the maximum on the PET curves. The mean and standard deviation were calculated based on the data sampled in the scoring area. Gamma index analysis is also applied in the comparison.Results: In the depth comparison, the 2 and 4 Gy dose cases yielded similar mean depth errors between 1 and −1 mm, and the deviation was &lt;2 mm. In the lateral comparison, the 2 Gy cases had a mean lateral error around 1 mm, and the 4 Gy cases had a mean lateral error &lt;1 mm, with a standard deviation &lt;1 mm for both the 2 and 4 Gy cases. All the cases have a gamma passing rate over 95%.Conclusion: The comparison of these PMMA phantom cases revealed good agreement between the predicted and measured PET data, with depth and lateral position errors &lt;2 mm in total, considering the uncertainty. The comparison results demonstrate that the PET predictions obtained in PMMA phantom tests for single proton beam therapy verification are reliable and that the research can be extended to verification in human body treatment with further investigation

Effect of Small Molecular Organic Acids on the Structure and Catalytic Performance of Sol–Gel Prepared Cobalt Cerium Oxides towards Toluene Combustion

Cobalt cerium oxide catalysts with small molecular organic acids (SOAs) as chelating agents were prepared via the sol&ndash;gel method and investigated for the complete oxidation of toluene. Four kinds of natural SOAs, i.e. malic acid (MA), citric acid (CA), glycolic acid (GA), and tartaric acid (TA), were selected. The effect of organic acids on the composition, structure, morphology and catalytic performance of metal oxides is discussed in details. The cobalt cerium oxides catalysts were characterized by various techniques, including TG&ndash;DSC, XRD, SEM&ndash;EDS, N2&ndash;adsorption and desorption, XPS, and H2&ndash;TPR analyses. The results show that the nature of organic acids influenced the hydrolysis, condensation and calcination processes, as well as strongly affected the textural and physicochemical properties of the metal oxides synthesized. The best catalytic activity was obtained with the CoCe&ndash;MA catalyst, and the toluene conversion reached 90% at 242 &deg;C. This outstanding catalytic activity could be related to its textural, redox properties and unique surface compositions and oxidation states. In addition, the CoCe&ndash;MA catalyst also showed excellent stability in long&ndash;time activity test

Influence of Sludge Initial pH on Bioleaching of Excess Sludge to Improve Dewatering Performance

pH has an important effect on the physiological activity of eosinophilic microorganisms. Therefore, this study used excess sludge produced by the mixed treatment of leachate and municipal sewage to explore the impact of different sludge initial pH on microbial biochemical reactions associated with the performance of excess sludge dehydration. Shake-flask tests were performed using inoculated microorganisms and fresh excess sludge in 500 mL Erlenmeyer flasks at a ratio of 1:4, with the addition of 2 g/L S0 and 6 g/L FeS2 as energy sources. Erlenmeyer flasks were shaken for 72 h at 180 rpm and 28 &deg;C, in a reciprocating constant homeothermic oscillating water-bath. Results show that the specific resistance to filtration (SRF) of the bioleached excess sludge decreased from (1.45~6.68) &times; 1012 m/kg to (1.21~14.30) &times; 1011 m/kg and the sedimentation rate increased from 69.00~73.00% to 81.70~85.50%. The SRF decreased from 1.45 &times; 1012 m/kg to 1.21 &times; 1011 m/kg and the sedimentation rate increased from 69.00% to 85.00%, which both reached the highest level when the initial pH of the excess sludge was 5 and the bioleaching duration was 48 h. At this time, the rates of pH reduction and oxidative redox potential (ORP) reached the highest values (69.67% and 515 mV, respectively). Illumina HiSeq PE250 sequencing results show that the dominate microbial community members were Thiomonas (relative abundance 4.59~5.44%), which oxidize sulfur and ferrous iron, and Halothiobacillus (2.56~3.41%), which oxidizes sulfur. Thus, the acidic environment can promote microbial acidification and oxidation, which can help sludge dewatering. The presence of dominant sulfur oxidation bacteria is the essential reason for the deep dehydration of the bioleached sludge

The research on CO oxidation over Ce–Mn oxides : the preparation method effects and oxidation mechanism

A series of CeO2-MnOx for highly efficient catalytical oxidation of carbon monoxide were prepared by citrate sol-gel (C), hydrothermal (H) and hydrothermal-citrate complexation (CH) methods. The outcome indicates that the catalyst generated using the CH technique (CH-1:8) demonstrated the greatest catalytic performance for CO oxidation with a T50 of 98 °C, and also good stability in 1400 min. Compared to the catalysts prepared by C and H method, CH-1:8 has the highest specific surface of 156.1 m2 g−1, and the better reducibility of CH-1:8 was also observed in CO-TPR. It is also observed the high ratio of adsorbed oxygen/lattice oxygen (1.5) in the XPS result. Moreover, characterizations by the TOF-SIMS method indicated that obtained catalyst CH–Ce/Mn = 1:8 had stronger interactions between Ce and Mn oxides, and the redox cycle of Mn3++Ce4+ ↔ Mn4++Ce3+ was a key process for CO adsorption and oxidation process. According to in-situ FTIR, the possible reaction pathway for CO was deduced in three ways. CO directly oxidize with O2 to CO2, CO adsorbed on Mn4+ and Ce3+ reacts with O to form intermediates (COO−) (T > 50 °C) and carbonates (T > 90 °C), which are further oxidized into CO2

Enhancing stability of copper-based catalysts by regulating of oxygen vacancy for resourcing HCl waste gas

The utilization of copper-based catalysts for converting by-product hydrogen chloride (HCl) into chlorine gas (Cl2) offers a promising method for efficient management of HCl waste gas. However, a significant challenge in this process lies in catalyst deactivation, primarily attributed to the loss of active component in the form of Cu-Cl. In this study, we synthesized a Cu2.4CeV0.5Oxcatalyst that exhibited remarkable performance, achieving a spacetime yield of 2.26 g Cl2/gcat*h with stable conversion efficiency at approximately 83 % maintained over 600 h. This level of stability represents a substantial improvement compared to previous studies of copper-based catalysts. In-situ DRFITS combined with ToF-SIMS confirms the reduction evolution of metal-Cl bonds. Additionally, ab-initio calculations elucidated that the rate-limiting step involves oxygen vacancy replenishment by O2 rather than Cl over CeO2 and CeVO4, thereby inhibiting Cu-Cl bond formation. This study introduces a novel approach for efficienct treatment of HCl waste gas, paving the way for its potential industrial application