Stereo-Preference in the degradation of the erythro and threo isomers of β-O-4-type lignin model compounds in oxidation processes. part 2: In the reaction with hydroxyl and oxyl anion radicals under hydrogen peroxide bleaching conditions

We examined which isomer, the erythro or threo, of non-phenolic β-O-4-type lignin model compounds is stereo-preferentially attacked by hydroxyl radical and its conjugate base, oxyl anion radical, generated by the decomposition of hydrogen peroxide in the presence of ferric ion and its precipitates under hydrogen peroxide bleaching conditions. The intrinsic stereo-preference of oxyl anion radical was slightly toward the erythro isomer, while hydroxyl radical had a further smaller stereo-preference. These stereo-preferences can be explained by our prior knowledge that oxyl anion radical preferentially attacks the side-chain of the lignin model compounds rather than the aromatic nucleus. The amount of the degraded lignin model compounds became less great with decreasing pH, but reversely and intensively greater in the pH range below 10. This phenomenon can be attributed to the change in the decomposition mechanism of hydrogen peroxide accompanying the pH variation.     

Fabrication using sequence wet-chemical coating and electrochemical performance of Ni–Fe-foam-supported solid oxide electrolysis cell for hydrogen production from steam

Ni–Fe-alloy-foam supported solid oxide electrolysis cell with an arrangement of nickle and Sc_0.1Ce_0.005Gd_0.005Zr_0.89O₂ (Ni-SCGZ) cathode, SCGZ electrolyte and Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-δ (BSCF) anode is successfully fabricated by the sequence wet-chemical coating. The multi-layer cathode with a gradient of thermal expansion coefficient (TEC) is deposited on the alloy-foam support. Two-step firing processes are applied including cathode pre-firing (1373 K, 2 h) and electrolyte sintering (1623 K, 4 h) using slow heating rate enhanced with compressive loading. The fabricated cell shows current density of ?0.95 Acm^?2 at 1.1 V with H₂O:H₂ = 70:30 and 1073 K, providing hydrogen production rate at 4.95 × 10^?6 mol s^?1. However, performance degradation was observed with the rate of 0.08 V h^?1, which can be ascribed to the delamination of BSCF anode under operating at high current density.     

Effects of osmotic pretreatment and frying conditions on quality and storage stability of vacuum-fried pumpkin chips

The effects of osmotic (OP), ultrasound-assisted osmotic pretreatment (UAOP) and frying conditions on quality and storage stability of vacuum fried pumpkin chips were investigated. The pumpkin samples were pretreated in maltodextrin solution and subsequently fried at different temperatures (90–110 °C) and time periods (10–30 min). The results demonstrated that the moisture content, water activity, lightness, yellowness and carotenoid content of the fried chips decreased, while oil content, hardness and a* (dark brown colour) value increased with increasing frying temperature and time. UAOP reduced about 16.0% of oil absorption and enhanced approximately 70% of carotenoid retention in the fried chips. UAOP samples were also more stable during storage than the untreated ones, indicated by lower degradation kinetics constants of key quality parameters. The proposed pretreatment could be an effective method for food industries to develop vacuum fried pumpkin chips with improved quality and stability.     

Stereo-Preference in the Degradation of the Erythro and Threo Isomers of β‐O‐4‐Type Lignin Model Compounds in Oxidation Processes: Part 1: In the Reaction with Active Oxygen Species Under Oxygen Delignification Conditions

We examined whether or not active oxygen species (AOS) stereo-preferentially attack the erythro or threo isomer of non-phenolic β-O-4 -type lignin model compounds under oxygen delignification conditions. When AOS were generated in situ by the reaction between O₂ and co-existing 4-hydroxy-3-methoxybenzyl alcohol (vanillyl alcohol), the obtained results could be explained on the basis of the hypothesis that an electrostatic repulsion exists between the negatively charged oxyl anion radical and the side-chain of the erythro isomer carrying the α-alkoxide anion. This repulsion prevents the reaction between the two species and, consequently, the erythro isomer is degraded less than the threo isomer. When 2,4,6-trimethylphenol (TMPh) was used to generate AOS, the reverse stereo-preference was observed. This reversal could be attributed to the neutral nature of a peroxyl radical that is an important AOS in the TMPh system and can attack the side-chain of the erythro isomer carrying the negatively charged α-alkoxide anion.     

Preparation of CeO2 Nano Rods Through a Sonication‐Assisted Precipitation

A CeO₂ nanopowder has been synthesized using sonication‐assisted precipitation. The use of ultrasonics during precipitation showed potential morphology control during synthesis. The sonication‐assisted precipitation with highly aqueous base (20 M NaOH) successfully induced the formation of a one‐dimensional nanostructure of CeO₂ rods with a homogeneous shape and size (TEM: 24 nm diameter and 129 nm long). A conventional precipitation under the same conditions provided the CeO₂ in nonuniform sizes and shapes. Heat treatment (1100°C for 4 h) was required for CeO₂ formation when (NH₄)₂C₂O₄ was used instead of NaOH. The concentration of the precipitation agent (15–20 M) strongly affected the size and shape of the product. Importantly, according to the temperature‐programmed reduction/oxidation study, the CeO₂ prepared using the sonication‐assisted route showed a relatively higher level of reversible oxygen storage capacity (2384 μmol/g), compared with the CeO₂ prepared by conventional route (1748 μmol/g).     

Hybrid Models for Breast Cancer Detection via Transfer Learning Technique

Currently, breast cancer has been a major cause of deaths in women worldwide and the World Health Organization (WHO) has confirmed this. The severity of this disease can be minimized to the large extend, if it is diagnosed properly at an early stage of the disease. Therefore, the proper treatment of a patient having cancer can be processed in better way, if it can be diagnosed properly as early as possible using the better algorithms. Moreover, it has been currently observed that the deep neural networks have delivered remarkable performance for detecting cancer in histopathological images of breast tissues. To address the above said issues, this paper presents a hybrid model using the transfer learning to study the histopathological images, which help in detection and rectification of the disease at a low cost. Extensive dataset experiments were carried out to validate the suggested hybrid model in this paper. The experimental results show that the proposed model outperformed the baseline methods, with F-scores of 0.81 for DenseNet + Logistic Regression hybrid model, (F-score: 0.73) for Visual Geometry Group (VGG) + Logistic Regression hybrid model, (F-score: 0.74) for VGG + Random Forest, (F-score: 0.79) for DenseNet + Random Forest, and (F-score: 0.79) for VGG + Densenet + Logistic Regression hybrid model on the dataset of histopathological images.     

Electrochemical performance of solid oxide electrolysis cell electrodes under high-temperature coelectrolysis of steam and carbon dioxide

The SOEC electrodes during steam (H₂O) electrolysis, carbon dioxide (CO₂) electrolysis, and the coelectrolysis of H₂O/CO₂ are investigated. The electrochemical performance of nickel-yttria stabilised zirconia (Ni-YSZ), Ni-Gd_0.1Ce_0.9O_1.95 (Ni-GDC), and Ni/Ruthenium-GDC (Ni/Ru-GDC) hydrogen electrodes and La_0.8Sr_0.2MnO_3−δ-YSZ (LSM-YSZ), La_0.6Sr_0.4Co_0.8Fe_0.2O_3−δ (LSCF), and La_0.8Sr_0.2FeO_3−δ (LSF) oxygen electrodes are studied to assess the losses of each electrode relative to a reference electrode. The study is performed over a range of operating conditions, including varying the ratio of H₂O/H₂ and CO₂/CO (50/50 to 90/10), the operating temperature (550-800 °C), and the applied voltage. The activity of Ni-YSZ electrodes during H₂O electrolysis is significantly lower than that for H₂ oxidation. Comparable activity for operating between the SOEC and solid oxide fuel cell (SOFC) modes is observed for the Ni-GDC and Ni/Ru-GDC. The overpotential of H₂ electrodes during CO₂ reduction increases as the CO₂/CO ratio is increased from 50/50 to 90/10 and further increases when the electrode is exposed to a 100% CO₂ (800 °C), corresponding to the increase in the area specific resistance. The electrodes exhibit comparable performance during H₂O electrolysis and coelectrolysis, while the electrode performance is lower in the CO₂-electrolysis mode. The activity of all the O₂ electrodes as an SOFC cathode is higher than that as SOEC anodes. Among these O₂ electrodes, LSM-YSZ exhibits the nearest to symmetrical behaviour.     

Effects of promoters on biomass gasification using nickel/dolomite catalyst

Metallic nickel has been selected as a catalyst for biomass gasification because of its activity in biomass steam gasification and tar reduction. The effects of types of promoters such as platinum, cobalt, and iron on biomass gasification were evaluated. The area of interest was the effects of preparation methods, which were impregnation and coprecipitation. Catalyst preparation by the impregnation method showed superior performance. The conclusion can be drawn from the experiments that the platinum promoter enhanced the reforming reaction, iron promoted a water-gas shift reaction, and the cobalt promoter favored a methanation reaction. Moreover, the addition of noble metal reduced carbon deposition on Ni/dolomite.     

Empirical models for estimating mercury flux from soils

Multiple parameters have been suggested to influence the exchange of mercury (Hg) between the atmosphere and soils. However, models applied for estimating soil Hg flux are simple and do not consider the potential synergistic and antagonist relationships between factors controlling the exchange. This study applied a two-level factorial experimental design in a gas exchange chamber (GEC) to investigate the individual and combined effects of three environmental factors (temperature, light, and soil moisture) on soil Hg flux. It was shown that individually irradiation, soil moisture, and air temperature all significantly enhance Hg evasive flux (by 90-140%). Synergistic effects (20-30% of additional flux enhancement) were observed for all two-factor interactions, with air temperature/soil moisture and air temperature/irradiation being the most significant. Results from the factorial experiments suggest that a model incorporating the second-order interactions can appropriately explain the flux response to the changes of the studied factors. Based on the factorial experiment results and using the flux data for twelve soil materials measured with a dynamic flux chamber (DFC) at various temperatures, soil moisture contents, solar radiation exposures, and soil Hg contents, two empirical models for estimating Hg flux from soils were developed. Model verification with ambient flux data not used to develop the models suggested that the models were capable of estimating dry soil Hg flux with a high degree of predictability (r ～ 0.9).