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The effect of the catalyst preparation method on the catalytic activity of Fe-ZSM-5 for the partial oxidation of methane with H2O2 in an aqueous phase was examined. UV–vis spectroscopy and FT-IR spectroscopy after NO adsorption were used to characterize the prepared catalysts. Various preparation methods, including wet impregnation, solid-state ion-exchange, chemical vapor impregnation, hydrothermal synthesis, and aqueous phase ion-exchange were compared. Among them, the aqueous phase ion-exchange method demonstrated the best results in producing isolated or oligonuclear extra-framework Fe species, which showed the highest catalytic activity. On the other hand, bulk iron oxides did not decompose H2O2 nor did they activate methane. The total product yield and the amount of H2O2 consumed increased with increasing Fe content in the case of the Fe-ZSM-5 catalyst prepared using an ion-exchange method. However, the fraction of less active Fe species, such as iron oxide clusters and larger iron oxide aggregates on the external crystal surface, increased with the Fe content, resulting in a decrease in the total product yield per Fe content and the amount of H2O2 consumed per Fe content.

Oxidation of micropollutants (MPs) by ozonation proceeds via the reactions with molecular ozone (O3) and hydroxyl radicals (•OH). To predict MP abatement during ozonation, a model that can accurately predict oxidant exposures (i.e., ∫ 0 t [ O 3 ] d t ⁢ a n d ⁢ ∫ 0 t [ O • H ] d t ) needs to be developed. This study demonstrates machine learning models based on the random forest (RF) algorithm to output oxidant exposures from water quality parameters (input variables) that include pH, alkalinity, dissolved organic carbon concentration, and fluorescence excitation-emission matrix (FEEM) data (to characterize organic matter). To develop the models, 60 different samples of natural waters and wastewater effluents were collected and characterized, and the oxidant exposures in each sample were determined at a specific O3 dose (2.5 mg/L). Four RF models were developed depending on how FEEM data were utilized (i.e., one model free of FEEM data, and three other models that used FEEM data of different resolutions). The regression performance and Akaike information criterion (AIC) were evaluated for each model. The models using high-resolution FEEM data generally exhibited high prediction accuracy with reasonable AIC values, implying that organic matter characteristics quantified by FEEM can be important factors to improve the accuracy of the prediction model. The developed models can be applied to predict the abatement of MPs in drinking water and wastewater ozonation processes and to optimize the O3 dose for the intended removal of target MPs. The machine learning models using higher-resolution FEEM data offer more accurate prediction by better calculating the complex nonlinear relationship between organic characteristics and oxidant exposures.

Fueled by the recognition of hydrogen as a promising renewable energy source for the future, there have been many attempts to find greener and more economical ways for its production from various sources. In this study, Methylomonas sp. DH-1, a type I methanotroph, was found to produce hydrogen using methane as a sole carbon source, under micro-aerobic conditions; this is analogous to the partial oxidation of methane in a thermochemical process based on metal catalysts. Flask cultures of Methylomonas sp. DH-1 were used to investigate the effects of different culture conditions on hydrogen production, including oxygen levels, methane/oxygen ratios, and initial cell densities. Methylomonas sp. DH-1 could produce hydrogen at an oxygen level below 4%, regardless of the methane content in the flask, implying that the critical factor for hydrogen production is the oxygen level, rather than the methane/oxygen ratio. Moreover, Methylomonas sp. DH-1 shows reversibility in hydrogen production and uptake, because the strain produces hydrogen under micro-aerobic conditions, uptakes it when the oxygen levels increase, and restores the hydrogen production capability when conditions become microaerobic again. Under initial conditions of 30% methane, 70% air, and an OD600nm of 6, hydrogen production was 26.87 μmol and its yields per methane and dry cell weight were 14.98 mmol-H2/mol-CH4 and 101.53 μmol-H2/g DCW, respectively, after 24 h of cultivation.

This study scrutinized the roles of sulfate radicals (SO4 −) and peroxydisulfate (PDS) formed from SO42− in electrochemical organic oxidation on a boron-doped diamond (BDD) electrode. The substrate-specific performance of electrochemical oxidation using SO42− as the electrolyte aligned with the reactivity of SO4 − produced via radiolysis- or heat-induced PDS activation, but was distinct from the non-selective oxidation efficiency observed in an aqueous ClO4− solution. A comparison of the treatment efficiencies using different electrolytes (i.e., Cl−, SO42−, and ClO4−) showed no pronounced enhancing effect of SO4 − on the anodic oxidation of diverse organics (except perfluorooctanoate), which implied that direct electron transfer and hydroxyl radical-induced oxidation proceeded as complementary reaction routes. Repeated electrolytic oxidation caused substantial electrolyte exchange from Cl− to ClO4−, which retarded organic oxidation accompanied by ClO4− accumulation. Conversely, high-yield PDS production observed when SO42− was used instead barely reduced treatment efficiency. Together with SO4 − detection in the electron paramagnetic resonance spectrum, a correlation between 4-chlorophenol oxidation rate and the faradaic efficiency for SO42− formation, monitored in PDS solutions while varying the cathode material, suggested cathodic PDS activation. The electrocatalytic performance was demonstrated to be further improved with anodically formed PDS activation through naturally occurring resistive heating or combination with UV photolysis as a post-treatment step.

In this study, we evaluate lanthanum strontium cobalt ferrite (LSCF) surface-coated with lanthanum nickelate (LNO) fabricated by aerosol-assisted chemical vapor deposition (AACVD) for application in solid oxide fuel cells (SOFCs). The AACVD method successfully produces LNO in the desired composition and crystal structure. The deposited LNO is confirmed to form a dense and uniform layer along the nano-porous LSCF support. The LSCF with an optimal amount of LNO surface clearly enhances the SOFC performance, showing a power increase of approximately 60% at 600 °C in our experiment. This enhancement results from the reduction of both ohmic and polarization resistance, presumably due to improved cathodic surface kinetics and current collection. This AACVD LNO-treatment is also confirmed to be effective in improving long-term stability, significantly suppressing the power decrease observed in an untreated sample.

ZSM-5 zeolite beads (ZB) modified with lanthanum (La) were prepared by impregnating ZB in a lanthanum nitrate solution (denoted as La-ZB). La-ZB was characterized via SEM, BET, ICP-OES and XRD techniques, which confirmed the doping of La on the surface of the ZB. The surface area and pore volume of La-ZB decreased marginally after the La-modification due to a partial pore blockage by the La dopant. La-ZB showed an improved phosphate adsorption compared to ZB, and the maximum phosphate adsorption capacities by ZB and La-ZB (determined by Langmuir isotherm) were 59.8 and 106.2 mg/g, respectively. Moreover, the adsorption kinetics proceeded according to the mechanism of the pseudo-second-order model. The phosphate adsorption by La-ZB exhibited an optimum at pH 6. In regeneration process of phosphate-loaded La-ZB, five times adsorption-desorption cycles were applied and 81.8% phosphate was recovery. In a test using wastewater containing a high phosphate concentration (218.6 mg/L), La-ZB exhibited 96.8% phosphate removal, which is 1.8 times higher than that of ZB (53.5%). The results indicate that La-ZB can be a promising recyclable adsorbent for the removal and recovery of phosphate from wastewater.

The morphological, nutritional, and functional characteristics of cultivated mountain ginseng (Panax ginseng C.A. Meyer, CMG) with different ages (3, 5, 7, and 9 years old) were investigated. Three-year-old CMG (3-CMG) was significantly smaller, shorter, and lighter than 5-CMG while there is no significant difference in length, thickness, and weight among 5-, 7-, and 9-CMGs. On the other hand, functional properties of CMG highly varied with the cultivation age. Moisture content of CMGs with different ages decreased with age except for 9-CMG whereas crude fat and protein contents increased with age. DPPH and ABTS radical scavenging activities were highest in 9-CMG (82.4 μg GAE/g and 723.6 μg AAE/g, respectively) while reducing poser was highest in 3-CMG (411.7 GAE/g). Xanthine oxidase inhibition activity of 9-CMG (17.24 μg AAE/g) was 1.5 times higher than that of 3-CMG. Acidic polysaccharide content was highest in 7-CMG (3,298 mg GAAE/g) but lowest in 3-CMG. Total polyphenol and flavonoid contents were highest in 5- and 7-CMG, respectively, and decreased with the cultivation period. Total ginsenoside content of CMG increased with the cultivation period. Rb1 and Re were predominant ginsenosides for all CMGs, accounting for about 50% of total ginsenoside content. Rb1 of 9-CMG was about four times higher than that of 3-CMG. Compound K was found in all CMGs, but it took less than 0.1% of total ginsenoside content.

In the recent climate change regime, industrial demand for renewable materials to replace petroleum-derived polymers continues to rise. Of particular interest is polyhydroxybutyrate (PHB) as a substitute for polypropylene. Accumulating evidence indicates that PHB is highly produced as a carbon storage material in various microorganisms. The effects of growth conditions on PHB production have been widely studied in chemolithotrophs, particularly in Rhodobacter. However, the results on PHB production in Rhodobacter have been somewhat inconsistent due to different strains and experimental conditions, and it is currently unclear how diverse environmental factors are linked with PHB production. Here, we report optimized growth conditions for PHB production and show that the growth conditions are closely related to reactive oxygen species (ROS) regulation. PHB accumulates in cells up to approximately 50% at the highest level under dark-aerobic conditions as opposed to light aerobic/anaerobic conditions. According to the time-course, PHB contents increased at 48 h and then gradually decreased. When observing the effect of temperature and medium composition on PHB production, 30 °C and a carbon/nitrogen ratio of 9:1 or more were found to be most effective. Among PHB biosynthetic genes, PhaA and PhaB are highly correlated with PHB production, whereas PhaC and PhaZ showed little change in overall expression levels. We found that, while the amount of hydrogen peroxide in cells under dark conditions was relatively low compared to the light conditions, peroxidase activities and expression levels of antioxidant-related genes were high. These observations suggest optimal culture conditions for growth and PHB production and the importance of ROS-scavenging signaling with regard to PHB production.

The oxidation kinetics of Cu through graphene were evaluated from the surface coverage of Cu oxide (Fox) by varying the oxidation time (tox = 10–360 min) and temperature (Tox = 180–240 °C) under an air environment. Fox, as a function of time, well followed the Johnson–Mehl–Avrami–Kolmogorov equation; thus, the activation energy of Cu oxidation was estimated as 1.5 eV. Transmission electron microscopy studies revealed that Cu2O formed on the top of the graphene at grain boundaries (G-GBs), indicating that Cu2O growth was governed by the out-diffusion of Cu through G-GBs. Further, the effect of Cu oxidation on graphene quality was investigated by measuring the electrical properties of graphene after transferring. The variation of the sheet resistance (Rs) as a function of tox at all Tox was converted into one curve as a function of Fox. Rs of 250 Ω sq−1 was constant, similar to that of as-grown graphene up to Fox = 15%, and then increased with Fox. The Hall measurement revealed that the carrier concentration remained constant in the entire range of Fox, and Rs was solely related to the decrease in the Hall mobility. The variation in Hall mobility was examined according to the graphene percolation probability model, simulating electrical conduction on G-GBs during Cu2O evolution. This model well explains the constant Hall mobility within Fox = 15% and drastic Fox degradation of 15–50% by the concept that the electrical conduction of graphene is disconnected by Cu2O formation along with the G-GBs. Therefore, we systematically developed the oxidation kinetics of Cu through graphene and simultaneously examined the changes in the electrical properties of graphene.

The microbial inactivation by cupric ion (Cu(II)) in combination with hydrogen peroxide (H2O2) and hydroxylamine (HA) was investigated for twelve different microorganisms (five Gram-negative bacteria, three Gram-positive bacteria, and four bacteriophages). The inactivation efficacy, protein oxidation, and RNA (or DNA) damage were monitored during and after treatment by Cu(II), Cu(II)/HA, Cu(II)/H2O2 and Cu(II)/HA/H2O2. The rate of microbial inactivation by the (combined) microbicides generally increased in the order of Cu(II) < Cu(II)/H2O2 < Cu(II)/HA < Cu(II)/HA/H2O2; Cu(II)/HA/H2O2 resulted in 0.18-0.31, 0.10-0.18, and 0.55-3.83 log inactivation/min for Gram-negative bacteria, Gram-positive bacteria, and bacteriophages, respectively. The degrees of protein oxidation and RNA (or DNA) damage increased in the order of Cu(II) < Cu(II)/HA < Cu(II)/H2O2 < Cu(II)/HA/H2O2. In particular, Cu(II)/HA/H2O2 led to exceptionally fast inactivation of the viruses. Gram-positive bacteria tended to show higher resistance to microbicides than other microbial species. The microbicidal effects of the combined microbicides on the target microorganisms were explained by the roles of Cu(I) and Cu(III) generated by the redox reactions of Cu(II) with H2O2, HA, and oxygen. Major findings of this study indicate that Cu(II)-based combined microbicides are promising disinfectants for different waters contaminated by pathogenic microorganisms.

Methane is considered a next-generation feedstock, and methanotrophic cell-based biorefinery is attractive for production of a variety of high-value compounds from methane. In this work, we have metabolically engineered Methylomicrobium alcaliphilum 20Z for 2,3-butanediol (2,3-BDO) production from methane. The engineered strain 20Z/pBudK.p, harboring the 2,3-BDO synthesis gene cluster (budABC) from Klebsiella pneumoniae, accumulated 2,3-BDO in methane-fed shake flask cultures with a titer of 35.66 mg/L. Expression of the most efficient gene cluster was optimized using selection of promoters, translation initiation rates (TIR), and the combination of 2,3-BDO synthesis genes from different sources. A higher 2,3-BDO titer of 57.7 mg/L was measured in the 20Z/pNBM-Re strain with budA of K. pneumoniae and budB of Bacillus subtilis under the control of the Tac promoter. The genome-scale metabolic network reconstruction of M. alcaliphilum 20Z enabled in silico gene knockout predictions using an evolutionary programming method to couple growth and 2,3-BDO production. The ldh, ack, and mdh genes in M. alcaliphilum 20Z were identified as potential knockout targets. Pursuing these targets, a triple-mutant strain ∆ldh ∆ack ∆mdh was constructed, resulting in a further increase of the 2,3-BDO titer to 68.8 mg/L. The productivity of this optimized strain was then tested in a fed-batch stirred tank bioreactor, where final product concentrations of up to 86.2 mg/L with a yield of 0.0318 g-(2,3-BDO) /g-CH4 were obtained under O2-limited conditions. This study first demonstrates the strategy of in silico simulation-guided metabolic engineering and represents a proof-of-concept for the production of value-added compounds using systematic approaches from engineered methanotrophs.

Peroxymonosulfate (PMS) activated by Hematite (α-Fe2O3) was capable of degrading different organic compounds. Several lines of experimental evidence are presented which argue against the generation of radical species as well as singlet oxygen (1O2). Tests using radical scavengers and probes, and electron paramagnetic resonance (EPR) spectroscopy suggested that the PMS-activation by α-Fe2O3 does not involve the generation of SO4•−, •OH, and O2•−. The possibility of 1O2 generation was also excluded by EPR spectroscopy and kinetic experiments performed in deuterium oxide. The ternary reactive complex that mediates the electron-transfer between target organic compounds and PMS (frequently proposed as a nonradical mechanism in previous studies) was not likely formed in this system. Based on the electrochemical analyses as well as other experiments, a high-valent iron species (most likely ferryl species, Fe(IV)) is believed to be responsible for the oxidation of organic compounds by the α-Fe2O3/PMS system.

Fe-ZSM-5 is an active catalyst for the selective oxidation of methane with H2O2 in liquid water. To prepare the active Fe-ZSM-5 catalyst, the effect of the Fe precursor on the catalytic performance was examined. Additionally, two preparation methods, wet impregnation (WI) and ion-exchange (IE), were also applied. The prepared catalysts were characterized using various techniques, such as nitrogen physisorption, X-ray diffraction, UV–Vis spectroscopy, and Fourier-transform infrared (FTIR) spectroscopy after NO adsorption (NO-FTIR). Fe-ZSM-5 prepared from FeCl2 appears to be the most active among the Fe-ZSM-5 catalysts prepared from FeCl2, FeSO4, Fe(CH3CO2)2, FeCl3, Fe2(SO4)3, Fe(C5H7O2)3, and Fe(NO3)3 using the WI method. For Fe-ZSM-5 catalysts prepared using the IE method, divalent Fe precursors, such as FeSO4, FeCl2, and Fe(CH3CO2)2, are better than trivalent Fe precursors, such as Fe2(SO4)3, FeCl3, and Fe(NO3)3, in terms of catalytic activity. The active catalyst has the dominant extra-framework Fe2+ species probed with UV–Vis spectroscopy and NO-FTIR.

The UV/H2O2 process is a benchmark advanced oxidation process (AOP) that in situ generates highly reactive and nonselective hydroxyl radical (•OH) to oxidatively destroy a wide range of organic compounds. Accurately quantifying the concentration of short-lived •OH is essential to predict process performance, optimize the operation parameters, and compare with other process options. The •OH concentration is typically measured using organic probe molecules that react with •OH but not with other oxidants. In the extremely well-characterized UV/H2O2 system in which •OH is proven to be the dominant oxidant, using photolysis-resistant probes such as benzoic acid and its derivatives is a widely agreed and practiced norm. We herein report that certain •OH probe compounds can be degraded in UV/H2O2 system by unknown reactive species that has not been reported in the past. Several common organic probes, particularly p-substituted benzoic acid compounds (i.e., p-hydroxybenzoic acid, p-chlorobenzoic acid, and p-phthalic acid), were found to be vulnerable to attack by the unknown reactive species, leading to false quantification of •OH concentration under high radical scavenging conditions. Lines of evidence obtained from a series of •OH scavenging experiments performed under various conditions (i.e., different concentrations of H2O2, •OH probe compounds, and dissolved oxygen) point toward excited state H2O2. The results from this study suggest the importance of using appropriate •OH probe compounds in mechanistic studies and needs for considering the unidentified role of excited state of H2O2 on the UV/H2O2 process and related AOPs.

Biofouling is one of the most important factors that degrade the performance of reverse osmosis (RO) membranes during the desalination process. This study demonstrates that copper ion (Cu(II) or Cu(II) plus hydroxylamine (HA) to produce Cu(I)) in combination with norspermidine (Nspd) can effectively inactivate bacterial biofilms on RO membranes. The addition of Nspd inhibited the inactivation of planktonic P. aeruginosa cells by copper ion. However, with respect to the cells in biofilms (grown in CDC reactors), the use of Nspd enhanced the cell inactivation by copper ion; the addition of Nspd increased the inactivation efficacies of Cu(II) and Cu(II)/HA against biofilm cells from 2.4 to 3.1 and from 1.3 to 3.5 (log inactivation in 1 h), respectively. Nspd disrupted extracellular polymeric substances (as evidenced by the removal of proteins and polysaccharides from biofilms), and it is believed to facilitate the penetration of copper ion into the biofilm matrix. These results showed that the Cu(II)/HA/Nspd treatment also inactivated biofilms in pressurized cross-flow RO filtration units, resulting in partial recovery of permeate flux. However, pretreatment using Nspd (and the subsequent treatment by copper ion) was not as effective as the simultaneous use of Nspd and copper ion in both CDC reactors and cross-flow filtration units.

Here, we developed a pressurized bioreactor system that increase carbon monoxide (CO) transfer efficiency in order to enhance the hydrogen productivity in the microbial water gas shift reaction by Thermococcus onnurineus NA1. The effects of CO pressure on the hydrogen production rate, CO consumption rate and the cell growth were investigated using small scale stainless steel bottles at various CO partial pressures. It was found that CO solubility increased by applying pressure can affect hydrogen production positively as long as the increased toxicity of CO is endurable to cells. The hydrogen productivity increased to some extent with CO pressure, but decreased drastically at the pressure higher than 4 bar. On the other hand, the effect of pressure itself on the cell's activity was not as significant as that of CO solubility increase. In the experiments at various system pressures with identical CO partial pressure of 1 bar, more than 80% of the cell activity remains even at total pressure of 10 bar. Also, it was important to determine the appropriate time to increase pressure for preventing excess CO in the reactor. Based on these results, a fermentation strategy for the pressurized system was designed and applied to a 5 L bioreactor with the continuous supply of the gas containing 60% CO. When the pressure was introduced to the bioreactor up to 4 bar at CO limitation condition, the unprecedented high productivity (360 mmol L−1 h−1) could be obtained.

Ferrous-tetrapolyphosphate complexes (Fe(II)-TPP) activate oxygen and hydrogen peroxide to produce reactive oxidants capable of degrading organic compounds. In this study, the Fe(II)-TPP/O2 and Fe(II)-TPP/H2O2 systems were assessed for oxidative degradation of microcystin-LR (MC-LR), the most toxic and abundant cyanotoxin. The degradation of MC-LR was optimized for both the Fe(II)-TPP/O2 and Fe(II)-TPP/H2O2 systems when the molar ratio of TPP:Fe(II) was approximately 5.7-5.9. The optimal H2O2 dose for MC-LR degradation by Fe(II)-TPP/H2O2 was found to be 320 μM. The Fe(II)-TPP/O2 and Fe(II)-TPP/H2O2 systems exhibited two pH optima for MC-LR degradation i.e., ∼7 and 9, which can be attributed to pH-dependent reactivity changes of the resultant oxidants (most likely the ferryl-tetrapolyphostate complex, Fe(IV)-TPP). Liquid chromatography-mass spectrometry identified 22 compounds produced by the oxidation of MC-LR, including four primary oxidation products. One of the primary products, in particular, was formed via oxidative cleavage of the alkene group in the Mdha moiety of MC-LR. This compound and its secondary oxidation products are rarely found when MC-LR is transformed by other oxidants and is believed to reflect a unique reaction pathway involving Fe(IV)-TPP. Meanwhile, the hepatotoxicity of the reaction solution decreased concurrently with a decrease on MC-LR concentration.

The F420-reducing hydrogenase of methanogens functions in methanogenesis by providing reduced coenzyme F420 (F420H2) as an electron donor. In non-methanogens, however, their physiological function has not been identified yet. In this study, we constructed an ΔfrhA mutant, whose frhA gene encoding the hydrogenase α subunit was deleted, in the non-methanogenic Thermococcus onnurineus NA1 as a model organism. There was no significant difference in the formate-dependent growth between the mutant and the wild-type strains. Interestingly, the mutation in the frhA gene affected the expression of genes involved in various cellular functions such as H2 oxidation, chemotactic signal transduction, and carbon monoxide (CO) metabolism. Among these genes, the CO oxidation gene cluster, enabling CO-dependent growth and H2 production, showed a 2.8- to 7.0-fold upregulation by microarray-based whole transcriptome expression profiling. The levels of proteins produced by this gene cluster were also significantly increased not only under the formate condition but also under the CO condition. In a controlled bioreactor, where 100% CO was continuously fed, the ΔfrhA mutant exhibited significant increases in cell growth (2.8-fold) and H2 production (3.4-fold). These findings strongly imply that this hydrogenase is functional in non-methanogens and is related to various cellular metabolic processes through an unidentified mechanism. An understanding of the mechanism by which the frhA gene deletion affected the expression of other genes will provide insights that can be applied to the development of strategies for the enhancement of H2 production using CO as a substrate.

The inactivation of C. polykrikoides , a red tide dinoflagellate, by ozonation was investigated in seawater by monitoring numbers of viable and total cells. Parameters affecting the inactivation efficacy of C. polykrikoides such as the ozone dose, initial cell concentration, pH, and temperature were examined. The viable cell number rapidly decreased in the initial stage of the reaction (mostly in 1–2 min), whereas the decrease in total cell number was relatively slow and steady. Increasing ozone dose and decreasing initial cell concentration increased the inactivation efficacy of C. polykrikoides , while increasing pH and temperature decreased the cell inactivation efficacy. The addition of humic acid (a promoter for the ozone decomposition) inhibited the inactivation of C. polykrikoides , whereas bicarbonate ion (an inhibitor for the ozone decomposition) accelerated the C. polykrikoides inactivation. Observations regarding the effects of pH, temperature, humic acid, and bicarbonate ion collectively indicate that the inactivation of C. polykrikoides by ozonation is mainly attributed to oxidative cell damages by molecular ozone, rather than by hydroxyl radical, produced during the ozone decomposition. At high ozone dose (e.g., 5 mg/L), hypobromous acid formed by the reaction of bromide with ozone may partially contribute to cell inactivation. The use of ozone of less than 1 mg/L produced 0.75–2.03 μg/L bromate.

While the hydrogen economy is receiving growing attention, research on microbial hydrogen production is also increasing. Microbial water–gas shift reaction is advantageous as it produces hydrogen from by product gas including carbon monoxide (CO). However, CO solubility in water is the bottleneck of this process by low mass transfer. Thermococcus onnurineus NA1 strain can endure a high-pressure environment and can enhance hydrogen production in a pressurized reactor by increasing CO solubility. As CO causes cell toxicity, two important factors, pressure and input gas flow rate, should be considered for process control during cultivation. Hence, we employed different operational strategies for enhancing hydrogen production and obtained 577 mmol/L/h of hydrogen productivity. This is the highest hydrogen productivity reported to date from microbial water–gas shift reaction.

Developing a cost-effective method for the separation and recovery of nanomaterials for water treatment is challenging due to the significantly high recovery cost associated with nanomaterial-based water treatment processes. In this study, we synthesized magnetically separable iron oxide/tungsten oxide (Fe2O3/WO3) composites through a chemical co-precipitation method and employed them as peroxymonosulfate (PMS) activators for the degradation of organic pollutants under visible light. Electron spin resonance analysis, chemical quenching, and photoluminescence analysis suggested that hydroxyl radicals, sulfate radicals, and valence band holes contribute to the degradation processes in the Fe2O3/WO3/PMS system under visible light. The results of the degradation and recovery experiments based on the mass ratio of WO3 to Fe2O3 ([WO3]:[Fe2O3]) in the Fe2O3/WO3 composite indicated that the Fe2O3/WO3 composite with [WO3]:[Fe2O3] = 2:1, which can be completely recovered using a magnet (magnetic flux density = 2500 G), is the optimal photocatalyst for PMS activation. The effects of reaction parameters, such as the PMS concentration, Fe2O3/WO3 dosage, solution pH, and background anions (chloride, carbonate, nitrate, and phosphate)/humic acid, on the degradation kinetics were investigated and discussed. Under visible light irradiation, the Fe2O3/WO3/PMS system efficiently degraded various organic pollutants, including 4-chlorophenol, 2-chlorophenol, 4-bromophenol, 4-methylphenol, 2,4-dimethylphenol, bisphenol A, tryptophan, sulfamethoxazole, sulfisoxazole, and furfuryl alcohol. In addition, the complete degradation of 4-chlorophenol in the Fe2O3/WO3/PMS system under visible light was achieved for up to five degradation cycles when Fe2O3/WO3 was reused after recovery using a magnet.

The effect of ferric ions (Fe3+) on the degradation of organic pollutants through the photocatalytic activation of peroxymonosulfate (PMS) was investigated. In the presence of Fe3+, the degradation of 4-chlorophenol (4-CP) was significantly enhanced in the PMS/tungsten oxide (WO3) system under visible light irradiation. The enhanced degradation efficiency by Fe3+ is primarily ascribed to the role of Fe3+ as an electron-transfer mediator, as it induces a cascadal electron transfer from WO3 to Fe3+ to PMS. The production of the sulfate radical (SO4 −) and its significant contribution to the degradation of 4-CP in the Fe3+/PMS/WO3 system were verified via electron paramagnetic resonance (EPR) spectroscopy and degradation experiments using radical scavengers (methanol and tert-butyl alcohol), respectively. The addition of Fe3+ to the PMS/WO3 system also significantly increased the degradation rate of other organic pollutants, such as phenol, 2,4-dimethylphenol, bisphenol A, sulfamethoxazole, sulfanilamide, and propranolol. The degradation efficiency of the Fe3+/PMS/WO3 system was largely maintained in multiple degradation cycles by the regular addition of PMS only. In addition, the Fe3+/PMS/WO3 system exhibited a higher degradation efficiency than the conventional cobaltous ion (Co2+)/PMS system at equal transition metal ion concentrations. The addition of Fe3+ for the purpose of enhancing the degradation efficiency is not restricted to the PMS activation system. This method can be applied to the activation of other oxyanions, such as peroxydisulfate (S2O82−) and bromate (BrO3−), for wastewater treatment.

Microbial biotransformation of CH4 gas has been attractive for the production of energy and high-value chemicals. However, insufficient supply of CH4 in a culture medium needs to be overcome for the efficient utilization of CH4. Here, we utilized cellulose nanocrystals coated with a tannic acid-Fe3+ complex (TA-Fe3+CNCs) as a medium component to enhance the gas-liquid mass-transfer performance. TA-Fe3+CNCs were well suspended in water without agglomeration, stabilized gas bubbles without coalescence, and increased the gas solubility by 20 % and the kLa value at a rapid inlet gas flow rate. Remarkably, the cell growth rate of Methylomonas sp. DH-1 as model CH4-utilizing bacteria improved with TA-Fe3+CNC concentration without any cytotoxic or antibacterial properties, resulting in higher metabolite production ability such as methanol, pyruvate, formate, and succinate. These results showed that TA-Fe3+CNCs could be utilized as a significant component in the culture medium applicable as a promising nanofluid for efficient CH4 microbial biotransformation.

Nanoparticulate zero-valent iron (nZVI) coupled with tetrapolyphosphate (TPP) (nZVI/TPP) was examined for the degradation of organic compounds, such as trichloroethylene (TCE), pentachlorophenol (PCP), and phenol, and the effects of TPP on the stability and toxicity of nZVI were studied. A sequential redox treatment (i.e., anoxic followed by oxic treatment) was attempted as a means to improve the utilization of nZVI for compound degradation. In the first anoxic treatment, chlorinated organic compounds, such as TCE and PCP, were degraded reductively by electron transfer from nZVI to the compounds at relatively slow rates. In the following oxic treatment, all organic compounds were rapidly degraded by the reactive oxidant (Fe(IV) species) produced via the reaction of the Fe(II)–TPP complexes with oxygen. In both anoxic and oxic treatment stages, the nZVI/TPP system exhibited greater activity in the degradation of organic compounds than that of nZVI alone. The anoxic/oxic reactivity of nZVI/TPP was affected by the pH and nZVI dose. The coupling of nZVI with TPP also enhanced the stability of nZVI; TPP was observed to inhibit the agglomeration and sedimentation of nZVI. In addition, the bacterial toxicity of nZVI and its oxidation products (i.e., Fe(II) and Fe(III)) was significantly reduced by the addition of TPP; TPP lowered the degree of E. coli inactivation by nZVI and its products, mitigating cell membrane damage.

To date, three main gasotransmitters, that is, hydrogen sulfide (H2S), carbon monoxide (CO), and nitric oxide (NO), have been discovered to play major bodily physiological roles. These gasotransmitters have multiple functional roles in the body including physiologic and pathologic functions with respect to the cellular or tissue quantities of these gases. Gasotransmitters were originally known to have only detrimental and noxious effects in the body but that notion has much changed with years; vast studies demonstrated that these gasotransmitters are precisely involved in the normal physiological functioning of the body. From neuromodulation, oxidative stress subjugation, and cardiovascular tone regulation to immunomodulation, these gases perform critical roles, which, should they deviate from the norm, can trigger the genesis of a number of neurodegenerative diseases such as Alzheimer’s disease (AD) and Parkinson’s disease (PD). The purpose of this review is to discuss at great length physical and chemical properties and physiological actions of H2S, NO, and CO as well as shedding light on recently researched molecular targets. We particularly put emphasis on the roles in neuronal inflammation and neurodegeneration and neuronal repair.

Nanostructured materials feature a high surface-to-volume ratio and small dimensions, which are highly beneficial for sensor applications. In this work, graphite was physically exfoliated by a conducting polymer polyaniline (PANI), which resulted in the formation of random-alternating layered graphene/PANI (G-PANI) nanoarchitectures. Resistometric sensors were assembled using a G-PANI nanoarchitecture film as the transducer electrode to examine the characteristics of the G-PANI nanoarchitectures in sensor applications. The sensing performance of the electrode depended on the type of dopant employed, and more importantly, the unique geometrical composition of the nanoarchitecture gave rise to anisotropic electrical properties. A series or parallel connection-like configuration of intercalated PANI nanolayers was formed when a voltage was applied perpendicular or parallel to the stacked graphene plane. Compared with the parallel connection-like configuration, the series connection-like configuration yielded...

Oxidation by persulfates at elevated temperatures (thermally activated persulfates) disintegrates bacterial cells and extracellular polymeric substances (EPS) composing waste-activated sludge (WAS), facilitating the subsequent sludge dewatering. The WAS disintegration process by thermally activated persulfates exhibited different behaviors depending on the types of persulfates employed, that is, peroxymonosulfate (PMS) versus peroxydisulfate (PDS). The decomposition of PMS in WAS proceeded via a two-phase reaction, an instantaneous decomposition by the direct reaction with the WAS components followed by a gradual thermal decay. During the PMS treatment, the WAS filterability (measured by capillary suction time) increased in the initial stage but rapidly stagnated and even decreased as the reaction proceeded. In contrast, the decomposition of PDS exhibited pseudo first-order decay during the entire reaction, resulting in the greater and steadier increase in the WAS filterability compared to the case of PMS. The treatment by PMS produced a high portion of true colloidal solids (1 μm) and eluted soluble and bound EPS, which is detrimental to the WAS filterability. However, the observations regarding the dissolved organic carbon, ammonium ions, and volatile suspended solids collectively indicated that the treatment by PMS more effectively disintegrated WAS compared to PDS, leading to higher weight (or volume) reduction by postcentrifugation.

In this study, lanthanum strontium cobalt ferrite cathodes surface-treated with lanthanum strontium cobaltite nanoparticles are synthesized using inkjet printing and their performances are evaluated using intermediate-temperature solid oxide fuel cells. The porous lanthanum strontium cobalt ferrite cathode of an anode-support solid oxide fuel cell is prepared under optimized inkjet printing conditions. The surface treatment is performed by infiltrating a lanthanum strontium cobaltite ink followed by calcination. The lanthanum strontium cobalt ferrite cathode is evenly surface-covered with lanthanum strontium cobaltite nanoparticles, confirming the effectiveness of the inkjet printing for the cathode surface modification. The fuel cell performances are evaluated in the intermediate temperature range of 550–650 °C. The power is significantly improved even with a small addition of the surface lanthanum strontium cobaltite; the enhancement factor reaches the value of five. An electrochemical impedance analysis confirms that the enhanced fuel cell performance is attributed to the reduced polarization impedance, significantly activating the surface catalysis. The addition of lanthanum strontium cobaltite retained the stability of the lanthanum strontium cobalt ferrite cell. However, an excessive amount of lanthanum strontium cobaltite significantly reduces the cell performance.

Numerous industries discharge substantial amounts of carbon monoxide (CO) into the atmosphere as waste; utilizing CO-containing industrial waste gases to produce useful organic chemicals has recently attracted attention. Here, we constructed a two-stage biocatalytic CO-conversion system for producing poly-3-hydroxybutyrate (PHB), a promising degradable biopolymer. In the first stage, Acetobacterium woodii, an acetogenic bacterial strain containing CO dehydrogenase (CODH) and formate dehydrogenase (FDH), was used as a whole-cell biocatalyst to transform CO into formate independent of an external reducing agent, such as H2. The conversion yield and specificity were close to 100% when the strain’s energy metabolism was blocked to suppress acetate production. The resulting formate was fed to a second bioreactor, where it was converted to PHB by engineered Methylbacterium extorquens AM1. The two-stage bioconversion of CO to a valuable product via formate as an intermediate offers a novel and promising strategy for CO utilization.

Today, bioplastics are recognised as sustainable alternatives and one of the solutions to the crisis of petro-based plastics. The next-generation polymer poly(ethylene 2,5-furandicarboxlate) (PEF) has gained great popularity since it is associated with significant reduction of energy use and GHG emissions, as well as with superior barrier properties. This drop-in polymer is a promising 100% bio-based alternative to its petro-based counterpart poly(ethylene terephthalate) (PET). PEF can be effectively synthesised by polymerisation between 2,5-furandicarboxylic acid (FDCA) and ethylene glycol (EG), which represent biomass-derived building blocks. These bio-building blocks are an important commodity and platform chemicals that can be used for a variety of applications, including the synthesis of PEF. This review covers recent progress in the production of novel bio-building blocks for the preparation of PEF. Among various synthesis methods, we reviewed the catalytic conversion of biomass-derived hydroxylmethylfurfural (HMF) into FDCA and the biological route from biomass feedstock into EG. In addition, we covered recent progress in the synthesis of HMF from biomass since a reliable supply of HMF is important for the synthesis of FDCA. Finally, research goals and challenges for future development of bio-building blocks production were proposed.

A new method for the activation of peroxymonosulfate (PMS) using ferric ions (Fe3+) and visible light (λ > 420 nm) was developed and investigated as a water treatment method for the degradation of various organic pollutants. Complete degradation of 100 μM of 4-chlorophenol (4-CP) was achieved after 60 min in the presence of PMS (1 mM) and Fe3+ (1 mM) under visible-light irradiation. However, the degradation of 4-CP was negligible or minor in the absence of either PMS, Fe3+, or visible-light irradiation. The visible-light absorption of Fe3+ was enhanced through complexation with PMS (HSO5−−Fe(OH)2+), although PMS itself does not absorb visible light. Inner-sphere electron transfer in the HSO5−−Fe(OH)2+ complex under visible light generated sulfate (SO4 −) and hydroxyl radicals ( OH). The production of SO4 − and OH in the PMS/Fe3+/visible light system was verified by electron paramagnetic resonance (EPR) spectroscopy and fluorescence spectroscopy. The degradation of 4-CP was significantly reduced with isopropyl alcohol (as a scavenger for both OH and SO4 −), but only slightly reduced with tert-butyl alcohol (as a OH scavenger). This behavior suggests that SO4 − acts as a primary oxidant in the PMS/Fe3+/visible light system. The PMS/Fe3+/visible light system efficiently degraded a wide spectrum of organic pollutants (e.g., 4-CP, bisphenol A, 2,4-dimethylphenol, furfuryl alcohol, sulfamethoxazole, tryptophan, and sulfanilamide). In addition, the degradation efficiency of the PMS/Fe3+/visible light system remained constant over multiple cycles with the intermittent addition of PMS only.

This study presents a freezing method for accelerating the peroxymonosulfate (PMS)-mediated degradation process. The degradation of furfuryl alcohol (FFA) in the presence of PMS was markedly accelerated by freezing. The degradation efficiency of FFA was only 10.4% in aqueous solution at 25 °C, but 100% degradation was achieved in frozen solution at −20 °C after 3 h of reaction at [FFA] = 20 µM and [PMS] = 100 µM. This accelerated PMS-mediated degradation of FFA in the frozen solution is due to the concentration of both PMS and FFA in ice grain boundaries, which increases the collision frequency between PMS and FFA thereby facilitating redox transformation. The mapping images of PMS and FFA in the frozen sample obtained using confocal Raman microscopy provide clear evidence of the accumulation of PMS and FFA in the ice grain boundaries after freezing. The experimental results with sulfate radical (SO4 −) scavengers, no production of hydroxyl radicals ( OH) and SO4 −, and the highly pollutant-dependent degradation efficiency suggest that the PMS-mediated degradation in frozen solution primarily proceeds through the direct electron transfer from organic pollutants to PMS (non-radical mechanism) rather than the reaction of SO4 − or OH with organic pollutants (radical mechanism). The degradation efficiency of the PMS/freezing system was similar across the pH range of 3–10. In addition, the PMS/freezing system worked efficiently in the temperature range of −10 to −35 °C. This result implies that the PMS/freezing system can be operated without external energy in cold regions.

This study demonstrates new empirical models to predict the decomposition of ozone (O3) and the exposures of oxidants (i.e., O3 and hydroxyl radical, OH) during the ozonation of natural waters. Four models were developed for the instantaneous O3 demand, first-order rate constant for the secondary O3 decay, O3 exposure (∫[O3]dt), and OH exposure ((∫[ OH]dt)), as functions of five independent variables, namely the O3 dose, concentration of dissolved organic carbon (DOC), pH, alkalinity, and temperature. The models were derived by polynomial regression analysis of experimental data obtained by controlling variables in natural water samples from a single source water (Maegok water in Korea), and they exhibited high accuracies for regression (R2 = 0.99 for the three O3 models, and R2 = 0.96 for the OH exposure model). The three O3 models exhibited excellent internal validity for Maegok water samples of different conditions (that were not used for the model development). They also showed acceptable external validity for seven natural water samples collected from different sources (not Maegok water); the IOD model showed somewhat poor external validity. However, the OH exposure model showed relatively poor internal and external validity. The models for oxidant exposures were successfully used to predict the abatement of micropollutants by ozonation; the model predictions showed high accuracy for Maegok water, but not for the other natural waters.

Chlorendic acid (CA) is a recalcitrant groundwater contaminant for which an effective treatment technology does not currently exist. In this study, a series of batch experiments were conducted to investigate the treatment of CA by zero-valent iron (ZVI) under various water chemistry conditions. It was observed that CA was removed by ZVI via both adsorption and degradation, with the degradation rate being proportional to the fraction of CA adsorbed onto ZVI. The rate of CA degradation decreased as pH increased, presumably due to the passivation of ZVI and diminishing CA adsorption. Chloride (Cl-) did not appreciably affect CA adsorption and degradation, while sulfate (SO42-) significantly inhibited both processes because SO42- competed with CA for ZVI adsorptive sites. The rate of CA degradation was significantly accelerated by ZVI-associated Fe(II). Nine byproducts of CA transformation were identified by high-resolution mass spectrometry. The formation and subsequent degradation of these products revealed that the transformation of CA by ZVI occurred via a step-wise reductive dechlorination pathway. Overall, this study suggests that ZVI may be effective at remediating CA-contaminated sites.

The mass transfer performance of a string film reactor (SFR)&mdash, a bioreactor design for the aerobic bioconversion of methane&mdash, was investigated. The results showed that the SFR could achieve high mass transfer performance of gases, and the highest values of the mass transfer coefficients for oxygen and methane were 877.1 h&minus, 1 and 408.0 h&minus, 1, respectively. There were similar mass transfer coefficients for oxygen and methane in absorption experiments using air, methane, and air&ndash, methane mixed gas under the same liquid flow rate conditions, implying that each gas is delivered into the liquid without mutual interaction. The mass transfer performance of the SFR was significantly influenced by the liquid flow rate and the hydrophilicity of the string material, whereas the magnitude of the gas flow rate effect on the mass transfer performance depended on both the tested liquid flow rate and the gas flow rate. Furthermore, the mass transfer performance of the SFR was compared with those of other types of bioreactors.

Methane-utilizing methanotrophs are fascinating systems for methane bioconversion. Methylomonas sp. DH-1, a novel type I methanotroph isolated from brewery sludge, has been evaluated as a promising candidate for an industrial bio-catalyst. Succinate has been considered one of the top building block chemicals for the agricultural, food, and pharmaceutical industries. In this study, Methylomonas sp. DH-1 was engineered to accumulate succinate as a desired product. The TCA cycle and enzymes diverting carbon flux to acetate or formate were modified or deleted to improve succinate productivity. By deleting succinate dehydrogenase (sdh) in the TCA cycle, succinate production increased dramatically ∼10 times compared to that of the wild type. In addition, the maximum succinate titer of ∼134 mg/L (DS-GL) was achieved by integrating glyoxylate shunt enzymes from the E. coli MG1655 strain. Pyruvate formate lyase (pfl) and acetate kinase-phosphotransacetylase (ack-pta) genes were disrupted to further concentrate carbon flux to the TCA cycle. However, these additional disruptions of competitive pathways did not affect cell growth or succinate production positively. The mutant strain DS-GL, which showed the best succinate production, was grown in a fed-batch bioreactor, and higher cell growth and succinate production (∼195 mg/L succinate with 0.0789 g-succinate/g-methane yield) were achieved. In this study, we demonstrated a novel platform for microbial conversion of methane to succinate using methanotroph.

Certain tumors such as pancreatic ductal adenocarcinoma (PDAC) are known to contain a variety of hydrolytic enzymes including RNases and proteases that may lead to degradation of RNA and proteins during sample processing. For such tumor tissues with RNA instability, RNAlater containing a high concentration of quaternary ammonium sulfates that denature RNA-hydrolyzing enzymes is often used to protect RNAs from hydrolysis. Although a few studies have been carried out to determine the effect of RNAlater on DNA and RNA, whether RNAlater influences the proteome and phosphoproteome is largely unknown. In this study we carried out a systematic and comprehensive analysis of the effect of RNAlater on the proteome and phosphoproteome using high-resolution mass spectrometry. PDAC tissues from three patients were individually pulverized and the tissue powders of each patient were divided into two portions, one of which was incubated in RNAlater at 4 °C for 24 h (RNAlater tissue) while the other was kept at – 80 °C (frozen tissue). Comprehensive quantitative profiling experiments on the RNAlater tissues and the frozen tissues resulted in the identification of 99,136 distinct peptides of 8803 protein groups and 17,345 phosphopeptides of 16,436 phosphosites. The data exhibited no significant quantitative changes in both proteins and phosphorylation between the RNAlater tissues and the frozen tissue. In addition, the phosphoproteome data showed heterogeneously activated pathways among the three patients that were not altered by RNAlater. These results indicate that the tissue preservation method using RNAlater can be effectively used on PDAC tissues for proteogenomic studies where preservation of intact DNA, RNA and proteins is prerequisite. Data from this study are available via ProteomeXchange with the identifier PXD010710. Electronic supplementary material The online version of this article (10.1186/s12014-019-9239-z) contains supplementary material, which is available to authorized users.

Energy-saving, high-efficiency cell disruption is a critical step for recovery of thermolabile antioxidant astaxanthin from Haematococcus pluvialis cyst cells of rigid cell-wall structure. In this study, as room-temperature green solvents, 10 types of 1-ethyl-3-methylimidazolium ([Emim])-based ionic liquids (ILs) were compared and evaluated for their abilities to disrupt H. pluvialis cyst cells for astaxanthin/lipid extraction. Among the 10 ILs tested, 3 [Emim]-based ILs with HSO4, CH3SO3, and (CF3SO2)2N anions were selected based on astaxanthin/lipid extraction performance and synthesis cost. When pretreated with IL/water mixtures, intact cyst cells were significantly torn, broken or shown to release cytoplasmic components, thereby facilitating subsequent separation of astaxanthin/lipid by hexane. However, excess IL pretreatments at high temperature/IL dosages and longer incubation times significantly deteriorated lipid and/or astaxanthin. Under optimized mild conditions (6.7% (v/v) IL in water solution, 30 °C, 60 min), almost complete astaxanthin recoveries (>99%) along with moderate lipid extractions (∼82%) could be obtained.

Synaptic plasticity is important for maintaining normal neuronal activity and proper neuronal functioning in the nervous system. It is crucial for regulating synaptic transmission or electrical signal transduction to neuronal networks, for sharing essential information among neurons, and for maintaining homeostasis in the body. Moreover, changes in synaptic or neural plasticity are associated with many neuropsychiatric conditions, such as schizophrenia (SCZ), bipolar disorder (BP), major depressive disorder (MDD), and Alzheimer’s disease (AD). The improper maintenance of neural plasticity causes incorrect neurotransmitter transmission, which can also cause neuropsychiatric conditions. Gas neurotransmitters (gasotransmitters), such as hydrogen sulfide (H2S), nitric oxide (NO), and carbon monoxide (CO), play roles in maintaining synaptic plasticity and in helping to restore such plasticity in the neuronal architecture in the central nervous system (CNS). Indeed, the upregulation or downregulation of these gasotransmitters may cause neuropsychiatric conditions, and their amelioration may restore synaptic plasticity and proper neuronal functioning and thereby improve such conditions. Understanding the specific molecular mechanisms underpinning these effects can help identify ways to treat these neuropsychiatric conditions.

Spirulina has widely been highlighted as a source of bioactive material that can be impregnated into dressing materials. The aim of this study was to widen the application fields of Spirulina extract-containing nanofiber, which has been suggested as an attractive dressing material in several previous studies. The bioactivity release pattern, water absorbance, and mechanical strength must be controllable. Spirulina extract was physically impregnated inside a nanofiber without significant chemical bonding to polycaprolactone or alginate polymers. This led to an initial burst and continual release of bioactive molecules from the nanofiber. By altering the concentration of Spirulina extract, mechanical strength and water absorbance were controllable. In addition, the dressing patch showed no cytotoxicity towards human epithelial cells, not causing skin-irritation. This indicates that the coaxially fabricated patch is a controllable dressing material that can be customized to have a specific mechanical strength, water absorbance, and bioactive release pattern, making it suitable for wide applications.

Identifying direct substrates targeted by protein kinases is important in understanding cellular physiology and intracellular signal transduction. Mass-spectrometry based quantitative proteomics provides a powerful tool for comprehensively characterizing the downstream substrates of protein kinases. This approach is efficiently applied to receptor kinases which can be precisely, directly, and rapidly activated by some agent, such as a growth factor. However, non-receptor tyrosine kinase Abl lacks the experimental advantage of extracellular growth factors as immediate and direct stimuli. To circumvent this limitation, we combine a chemical rescue approach with quantitative phosphoproteomics to identify targets of Abl and their phosphorylation sites with enhanced temporal resolution. Both known and novel putative substrates are identified, presenting opportunities for studying unanticipated functions of Abl under physiological and pathological conditions.

Nanoparticles pack together to form macro-scale electrodes in various types of devices, and thus, optimization of the nanoparticle packing is a prerequisite for the realization of a desirable device performance. In this work, we provide in-depth insight into the effect of nanoparticle packing on the performance of nanoparticle-based electrodes by combining experimental and computational findings. As a model system, polypyrrole nanospheres of three different diameters were used to construct pseudocapacitive electrodes, and the performance of the electrodes was examined at various nanosphere diameter ratios and mixed weight fractions. Two numerical algorithms are proposed to simulate the random packing of the nanospheres on the electrode. The binary nanospheres exhibited diverse, complicated packing behaviors compared with the monophasic packing of each nanosphere species. The packing of the two nanosphere species with lower diameter ratios at an optimized composition could lead to more dense packing of the nanospheres, which in turn could contribute to better device performance. The dense packing of the nanospheres would provide more efficient transport pathways for ions because of the reduced inter-nanosphere pore size and enlarged surface area for charge storage. Ultimately, it is anticipated that our approach can be widely used to define the concept of "the best nanoparticle packing" for desirable device performance.

Graphene is a fascinating material with unique properties, such as high mechanical strength and excellent electronic and thermal conductivities, as well as many other beneficial properties. Despite much recent effort, the facile synthesis and colloidal stabilization of graphene in aqueous solutions remains central to both academic research and practical applications. Here, we provide an in-depth insight into how the hydrophobic moieties of polymers affect the physical exfoliation of graphite into graphenes in aqueous solution. Four different polymers with graphene-like moieties, such as phenyl- and pyrenyl-functionalized side chains, were synthesized on the basis of the two water-soluble polymers poly(vinyl alcohol) (PVA) and dextran. Simply, sonication of graphite with the polymers in an aqueous solution produced stable graphene dispersions even after centrifugation. The ability of the polymers to exfoliate graphene sheets from the graphite was systematically investigated. Notably, 10 wt % phenyl-PVA led...

Hydrogen sulfide (H2S), a toxic gaseous molecule, plays a physiological role in regulating homeostasis and cell signaling. H2S is produced from cysteine by enzymes, such as cystathionineβ-synthase (CBS), cystathionineγ-lyase (CSE), cysteine aminotransferase (CAT), and 3-mercaptopyruvate sulfurtransferase (3MST). These enzymes regulate the overall production of H2S in the body. H2S has a cell-signaling function in the CNS and plays important roles in combating oxidative species such as reactive oxygen species (ROS) and reactive nitrogen species (RNS) in the body. H2S is crucial for maintaining balanced amounts of antioxidants to protect the body from oxidative stress, and appropriate amounts of H2S are required to protect the CNS in particular. The body regulates CBS, 3MST, and CSE levels in the CNS, and higher or lower levels of these enzymes cause various neurodegenerative diseases. This review discusses how H2S protects the CNS by acting as an antioxidant that reduces excessive amounts of ROS and RNS. Additionally, H2S regulates cell signaling to combat neuroinflammation and protect against central neurodegenerative diseases such as Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease (HD), and amyotrophic lateral sclerosis (ALS).

Colchicine is an alkaloid widely used for the treatment of inflammatory diseases, such as gout. It suppresses cell division by inhibiting mitosis. We investigated the anticancer effects of colchicine on human hypopharyngeal cancer cells and the mechanisms underlying its anticancer effects. XTT cell proliferation assay showed that colchicine inhibited the growth and proliferation of human hypopharyngeal cancer cells (FaDu and SNU1041) in a dose- and time-dependent manner. Colchicine also inhibited the migration, invasion, and adhesion of hypopharyngeal cancer cells in a dose-dependent manner. The levels of mRNA expression and activity of matrix metalloproteinase-9 (MMP9) and urokinase-type plasminogen activator (uPA) decreased after treatment with colchicine. Further investigation revealed that colchicine inhibited the phosphorylation of the FAK/SRC complex and paxillin. Tumor volume ratios in colchicine-treated mice (0.1 mg/kg, every 2 days for 14 days) increased less than in control mice. To our knowledge, this is the first report showing that colchicine can suppress cell invasion, migration, and adhesion through reduced expression of MMP9, the uPA system, and the FAK/SRC complex. Colchicine has the potential to prevent disease progression in hypopharyngeal cancer and may have application as an adjunctive treatment.

Translation initiation generally occurs at AUG codons in eukaryotes, although it has been shown that non-AUG or noncanonical translation initiation can also occur. However, the evidence for noncanonical translation initiation sites (TISs) is largely indirect and based on ribosome profiling (Ribo-seq) studies. Here, using a strategy specifically designed to enrich N termini of proteins, we demonstrate that many human proteins are translated at noncanonical TISs. The large majority of TISs that mapped to 5′ untranslated regions were noncanonical and led to N-terminal extension of annotated proteins or translation of upstream small open reading frames (uORF). It has been controversial whether the amino acid corresponding to the start codon is incorporated at the TIS or methionine is still incorporated. We found that methionine was incorporated at almost all noncanonical TISs identified in this study. Comparison of the TISs determined through mass spectrometry with ribosome profiling data revealed that about two-thirds of the novel annotations were indeed supported by the available ribosome profiling data. Sequence conservation across species and a higher abundance of noncanonical TISs than canonical ones in some cases suggests that the noncanonical TISs can have biological functions. Overall, this study provides evidence of protein translation initiation at noncanonical TISs and argues that further studies are required for elucidation of functional implications of such noncanonical translation initiation.

The combination of Cu(II) with peroxymonosulfate (PMS) (i.e., the Cu(II)/PMS system) synergistically inactivated P. aeruginosa cells in the planktonic state, and in biofilms grown on RO membranes. The enhanced bacterial inactivation by the Cu(II)/PMS system appears to be due to the reactive oxidants produced by the catalytic reactions of the Cu(II)/Cu(I) redox couple with PMS. In the presence of chloride ion (Cl−), the Cu(II)/PMS system showed increased microbicidal effects on the planktonic P. aeruginosa cells, which was explained by the role of hypochlorous acid (HOCl) produced by the reaction of chloride with PMS. In addition, the combination of Cu(II) with HOCl showed synergistic microbicidal effects on the planktonic cells. Compared to planktonic cells, biofilm cells were more resistant to the Cu(II)/PMS treatment. Cl− did not significantly affect the inactivation of biofilm cells by the Cu(II)/PMS system. It is believed that the extracellular polymeric substances of biofilms play a role as oxidant sinks (particularly HOCl), protecting the cells inside the biofilm matrix. The HOCl-generating systems, such as PMS/Cl− and Cu(II)/PMS/Cl−, greatly degraded proteins and polysaccharides in biofilms. Experiments on the cross-flow filtration of NaCl solution showed that the Cu(II)/PMS treatment of fouled RO membranes resulted in partial recovery of permeate flux.