CO Groups Research Articles

Theoretical and experimental study of new deep eutectic solvents for extraction of perfluorinated iodoalkanes

There is a lack of attention and reporting in aspects of the neutral/nonionic perfluoroalkyl substances (PFASs) and corresponding treatment mechanisms. Herein, new function-oriented deep eutectic solvents (DESs) with pyridine moiety were designed for perfluorinated iodoalkanes extraction from the oil phase. The effect of hydrogen bond acceptor (HBA) functional groups on the effectiveness of targets retrieval was investigated. Moreover, different structural, quantum-chemical, solvatochromic, and statistical thermodynamics parameters were conducted, calculated, and correlated to the distribution coefficients of the studied DESs. Results showed that functional groups of HBAs significantly affected the extraction effectiveness of eutectic mixtures. The pyridine ring-based DESs with the CO group possessed the highest extraction efficiencies among the studied groups. To some extent, the extraction performances of the DES were substantially affected by the electrostatic potential extrema of the donor halogen atom and pyridine analogues. For targets with relatively short alkyl chain length, the topological indices had a positive relationship with the treatment efficacy of the DESs, and the quantum-chemical parameters of these solvents had a strong negative relationship with them. For targets with long alkyl chain length, the solvatochromic parameters of DES had a great influence on the distribution coefficients and also on the selectivity of these solvents. Furthermore, the halogen and hydrogen bonds presented cooperativity, clarifying via quantum-chemistry calculations. The synergism mechanism between them is beneficial to the extraction of perfluorinated iodoalkanes. Besides shedding light on the structure–property-performance relationships of the DESs, these findings also provided novel insights into the directional design and selection of DESs.

Equilibrium solubility, non-covalent interactions and solvation thermodynamics of thiamphenicol in aqueous cosolvents of n-propanol/acetone/acetonitrile

This study investigated the thermodynamic equilibrium solubility and its model correlation of thiamphenicol in aqueous solutions of n-propanol/acetone/acetonitrile as well as the solvation behavior of the compound. To explain the electrostatic properties of the basicity and the acidity of thiamphenicol molecule, a quantitative study of the molecular surface and a Hirshfeld surface analysis were utilized. These studies revealed that oxygen atoms in > SO2 and > CO groups are the most important electrophilic sites, and hydrogen atoms in –OH groups are the most important nucleophilic sites. An independent gradient model that was on the basis of the Hirshfeld partition was used to qualitatively clarify the inter-molecular interactions occurred between thiamphenicol and various solvents. At 101.1 kPa and temperatures ranging from 278.15 to 318.15 K with increments of 5 K, the isothermal dissolution technique was utilized to investigate the solubilities of this drug. The Apelblat equation, the modified van't Hoff Jouyban–Acree model, the Jouyban–Acree model, and the modified Wilson model all gave good findings for the solubility connection, with a relative average deviance of 3.41 percent. The extended Hildebrand solubility approach was used to inspect the solvation behavior at 298.15 K. The inverse Kirkwood-Buff integrals method was utilized in order to carry out the task of quantifying the thiamphenicol solvation that was favored. Positive solvation values in acetone/acetonitrile-rich and -middle solution compositions show that acetone/acetonitrile preferentially solvates thiamphenicol.

Efficient photocatalytic production of hydrogen peroxide by Z-scheme resorcinol-formaldehyde resin/g-C3N4 heterostructure under visible light

Photocatalytic production of hydrogen peroxide (H2O2) in pure water system under visible light is very desirable. Resorcinol-Formaldehyde (RF) resin has proven to be a promising photocatalyst for this purpose because of its high solar-to-chemical conversion (SCC) (∼0.5 %). However, RF resin prepared at low hydrothermal temperature is not satisfactory because the CO group, which is detrimental to the H2O2 production will only be generated when it is >250 °C. Herein, we successfully prepared a Z-scheme heterostructure between RF resin and g-C3N4 by mechanochemical method. The ball milled RF-g-C3N4 (RF-CN-bm) not only achieved CO group at a lower temperature (180 °C) but also produced as high as 72.86 umol H2O2 in 12 h under visible light, which is 2.37 times higher than that of bare RF resin. Moreover, we found that Z-scheme heterojunction was formed between RF and g-C3N4, which allowed the H2O2 production both through O2 reduction by CB e− of g-C3N4 and the combination of ∙HO that produced by oxidation of OH– by VB h+ of RF. In principle, the mechanochemical assembled RF-CN-bm developed in this study paves a new way for low-cost and high-performance H2O2 production under visible light.

X-ray structural study of human neutrophil elastase inhibition with a series of azaindoles, azaindazoles and isoxazolones

Our purpose was to structurally investigate through X-ray crystallography the inhibition mechanism of small molecule inhibitors of human neutrophil elastase (HNE), a serine protease associated with some serious chronic inflammatory diseases, especially pulmonary pathologies. In particular, we selected some of the compounds previously synthesized by our research group, such as 5/4-azaindole, azaindazole and isoxazolone derivatives, which are promising therapeutic agents with an inhibition potency in the nanomolar range. In this work, we adopted Porcine Pancreatic Elastase (PPE) as a structural model for its high homology with the human enzyme, especially in the active site. The crystallographic study allowed us to gain information about the binding mode and inhibition mechanism of these new HNE inhibitors. In fact, we obtained the structures of the complexes of PPE with a fragment of the inhibitors resulted from the nucleophilic attack by the catalytic residue Ser195. In this way we confirmed an acyl enzyme inhibition mechanism for all the inhibitor scaffolds used. Furthermore, for the isoxazolone derivatives which possess two carbonyl groups we identified the exocyclic CO group as the one susceptible to the Ser attack.

Improvement of peroxymonosulfate utilization efficiency for sulfamethazine degradation by photo-electron activating peroxymonosulfate: Performance and mechanism

Enhancing the utilization efficiency of oxidant is of great importance for advanced oxidation processes (AOPs). Herein, nitrogen-doped titania dioxide/carbon (NTC7) catalyst was fabricated via pyrolyzing NH2-MIL-125 under nitrogen atmosphere at 700 °C. Excitation of NTC7 under visible light can successfully achieve efficient activation of peroxymonosulfate (PMS) (NTC7 + PMS + Vis). Degradation performance and PMS activation mechanism were systematically investigated using sulfamethazine (SMT) as the target pollutant. It was found that the photo-generated electrons excited from NTC7 under visible light played the dominant role in enhancing the productive consumption of PMS. Its utilization increased by 66 % (Δ[PMS]/Δ[SMT] = 7.0) in NTC7 + PMS + Vis process and the degradation rate was 2.14 times higher than that of NTC7 + PMS process. The ketonic CO groups and structural defects were responsible for the generation of 1O2 in dark activation while radicals (•OH, O2•–) were more inclined to be continuously produced in NTC7 + PMS + Vis process. The involved degradation pathways, intermediates, and toxicity assessment have been studied in detail. This work provides an effective approach to enhance the utilization efficiency of oxidant for pollutant degradation by AOPs.

A carbothermic hybrid synthesized using waste halogenated plastic in sub/supercritical CO2 and its application for lithium recovery

Facile fabrication of porous carbon materials from waste halogenated plastic is highly attractive but frequently hampered due to potential release of halogenated organic pollutants. In this study, a novel type of carbon hybrid was tentatively synthesized from a real-world halogenated plastic as an inexpensive carbon source by sub/supercritical carbon dioxide carbonization technique. It was found that halogen-free carbon carrier was advantageously synthesized through carbonization of halogenated plastic without using catalysts due to zip depolymerization, random chain cracking and free radical reactions induced by sub/supercritical carbon dioxide technique. Exhibiting with more abundant functional groups including C–O, CO groups than pyrolytic carbon carrier, the derived carbon carrier demonstrated excellent performance in selective recovery of lithium from cathode powder with highest recovery efficiency of 93.6%. Mechanism study indicated that cathode powder was transformed into low-valence states of transition metals/metal oxides and released lithium as lithium carbonate due to collapse of oxygen framework via carbothermic reduction. This work provides an applicable and green process for synthesis of alternative carbon carrier from waste halogenated plastic and its application as carbothermic reductant in lithium recovery.

A novel multi-components hierarchical porous composite prepared from solid wastes for benzohydroxamic acid degradation

In this study, a novel carbon-wrapped-iron hierarchical porous catalyst (Fe/C-Mn800) was prepared from electrolytic manganese residue (EMR) and sewage sludge (SS), which showed outstanding degradation ability toward benzohydroxamic acid (BHA, nearly 90 % was removed within 60 min) with low metal leaching rate. Mechanism exploration found transition metal ions (Fe and Mn) can serve as electron acceptors and facilitate the generation of persistent free radicals (PFRs). These transition metal ions and PFRs mainly participated in the single-electron pathway via activating PMS to generate a large amount of reactive oxygen species (ROS). While the electron negative graphitic N and CO groups not only improve the electronegatively of catalyst, but also acted as the electron sacrificers to favor the electron transfer and directly oxidized the absorbed BHA through the ternary activated outer-sphere complexes. Eley–Rideal (E-R) and Langmuir–Hinshelwood (L-H) analysis further demonstrated the crucial role of pre-adsorption during the degradation process. This work provided a deep insight into the degradation mechanism of metal/carbon composite and promising opportunity widened the horizon of the high-value utilization of EMR and SS.

Ni-WC nanoparticles/carbon aerogel electrocatalytic electrode for methanol and urea electrooxidation

Direct methanol fuel cells and direct urea fuel cells are significant for mitigating the energy crisis and protecting the environment. However, as the common critical anodes for the electrooxidation of methanol and urea, most Ni-based catalysts are severely poisoned by the CO group, resulting in a decrease in current densities and stability of fuel cells. Herein, efficient bacterial cellulose (BC)-derived carbon aerogel loaded with Ni-based catalyst and WC nanoparticles co-catalyst was developed for the electrooxidation of methanol and urea. As a result, the catalytic electrode exhibits high electrocatalytic activity for methanol electrooxidation (105.7 mA cm−2 at 0.8 V) and urea electrooxidation (90.4 mA cm−2 at 0.8 V). The synergistic effect between Ni and WC can significantly weaken the surface adsorption of CO on the electrode to obtain excellent and durable electrochemical performance. For methanol oxidation reaction and urea oxidation reaction, the retentions of the peak current density after 2000 cycles in the original electrolytes are 48.94% and 74.79%, respectively. Moreover, applying the new electrolyte, the peak current density can return to 88.42% and 84.4% of the original value.

Mechanically robust self-repairing polyurea elastomers: The roles of hard segment content and ordered/disordered hydrogen-bonding arrays

It has been a challenge to impart high strength and toughness to room-temperature self-repairing polyurethane/polyurea materials. We report a room-temperature self-repairing thermoplastic polyurea elastomer (PU) with mechanical robustness. When thiosemicarbazide was used as a chain extender, strong (or weak) hydrogen bonds were formed between CO (or CS) and NH groups in the hard regions of PU. The results were optimized mechanical and self-repairing properties: the tensile strength, elongation at break, toughness, and self-repairing efficiency of the PU reached 4.43 MPa, 1498.37%, 55.14 MJ m−3, and 96.3%, respectively. We found that the increase of hard segments led to increased/decreased number of ordered/disordered hydrogen bonds, as well as enhancement of both the aggregation of hard segments and the degree of microphase separation. We proposed a model dealing with the relation between the hard segment content and the hydrogen-bonding arrays and explored the exchange rate and the order–disorder transition of hydrogen bonds, to provide an insight into the optimization of mechanical and self-repairing properties.

Characteristics of CO, CO2 generation and reactive group conversion in isothermal smoldering combustion of coal

The process of coal smoldering combustion will produce a significant number of CO and CO2 gases, causing environmental pollution and casualties. It is important to elucidate the law and mechanism of CO and CO2 generation during coal smoldering combustion. In this paper, the CO and CO2 production patterns and the relationship of reactive group conversion during isothermal smoldering combustion were investigated by TG-MS and FT-IR. Results reveal that the CO and CO2 generation curves with time during isothermal smoldering combustion of coal in the first stage conform to the polynomial function Y1=A1+B1t+C1t2+D1t3+E1t4, in the second stage accord with the complex exponential function Y2=A2+B2ekt (k < 0), as well as the CO + CO2 production curve. The consumption rate function of functional groups during isothermal smoldering combustion is calculated from the CO + CO2 production curve as v=L·YCO + CO21000000Vm. As the isothermal temperature rises, the rate of coal combustion in smoldering combustion accelerates, causing an exponential increase in CO + CO2 emissions and reactive group consumption. The CO and CO2 emissions vary considerably at different isothermal temperatures, which is due to the increase in the number and type of reactive groups involved in the reaction with rising temperature. During isothermal smoldering combustion of coal, in exception to the direct generation of CO and CO2 from carboxyl and carbonyl groups, aliphatic hydrocarbons are key groups for the continuous generation of CO and CO2, and are also important mediators for the formation of carboxyl and carbonyl groups. The hydroxyl group acts as a reactant at relatively low temperatures and plays an essential role in driving the reaction. The aromatic hydrocarbon is the principal source of CO and CO2 at higher temperatures. This study will help to forecast the degree of coal smoldering combustion and to control coal smoldering combustion.

Influence of Different Dye Substances on the Effectiveness of Bleaching and H2O2 Diffusion.

This study aimed to evaluate the influence of different dye substances on the effectiveness of bleaching and hydrogen peroxide diffusion (HO). From 300 central bovine incisors, 160 enamel/dentin disks with similar E* values were selected. The specimens were distributed according to the pigment treatment. Aiming to standardize the chromatic change provided by the different pigments, the specimens from each group remained immersed in the pigment solutions for different times (32 specimens per group): DW - distilled water (Control group); BT - black tea; CO - coffee; SD - cola-based soft drink; and RW - red wine. After pigmentation and chromatic change value analysis, only 10 specimens from each group (n=10) were selected, so the chromatic alteration of all groups was similar (ΔE=8.36±0.5). The samples were subjected to bleaching treatment and diffused peroxide was quantified in a visible ultraviolet light spectrophotometer. Two more bleaching sessions were conducted to evaluate ΔE and the Whiteness Index for Dentistry (ΔWID). Concurrently, solutions were prepared with dye agents, and the same ΔE value was obtained in the teeth (ΔE=8.49±0.5). The solutions received a standardized amount of H2O2, being analyzed by a visible ultraviolet light spectrophotometer. Data analysis comprised variance and Tukey's tests (α=0.05). Higher H2O2 diffusion was observed in pigmented groups when compared with DW (p<0.05). The CO and RW groups had the highest ΔE values (p>0.05), meaning greater difficulty in responding to treatment. In relation to ΔWID, RW bleached less than the other groups after the third bleaching session (p<0.05), resembling only the SD group (p=0.467). However, 21 days after ending the bleaching treatment, only RW and CO had the lowest values (p=0.481). Analysis of the solutions revealed that only RW was altered by the peroxide (p<0.05). In conclusion, teeth pigmented with coffee and, mainly, red wine were more resistant to bleaching treatment, although all pigmentations favored increases in transenamel and transdentinal H2O2 penetration.

Structure-property relationship and mechanism of peroxymonosulfate activation by nitrogen-doped biochar for organic contaminant oxidation

Nitrogen doping has been found to effectively promote the catalytic activation of peroxymonosulfate (PMS) by biochar in the application of organic contaminant degradation. However, the dominant active sites of nitrogen-doped biochar (NBC) and the exact catalytic oxidation mechanism in behind remain ambiguous. Herein, a series of NBC samples were prepared as PMS activators to facilitate oxidative degradation of 2,4-dichlorophenol, and the functions of nitrogen bond configurations, oxygen-containing groups, and structural defects were systematically investigated during catalytic oxidation. The oxidation rate constant shows a great positive linearity with the relative amount of ketonic (CO) groups and the defect level of biochar, which indicates that the CO groups and structural defects play a major role in PMS activation, acting as dominant active sites to promote the catalytic oxidation of NBC by generating O2·− and 1O2. This study offers new insight into the significant role of NBC during PMS activation and further provides theoretical support to guide the rational design of nitrogen doping strategies.

Deoxidation regulation of SiC surface and its effect on enhancing photocatalytic performance

In this study, the surface of SiC was deoxidized by a simple NaOH etching treatment at room temperature. The synthesized SiC catalysts were tested for the removal of MB dyes under UV irradiation. Strong alkali corrosion thinned the thickness of the blocking silicon oxide layer and also led to the presence of more electrophilic centers (consisting of polar > CO groups) on the surface. Compared with unetched SiC, the optimal photocatalytic efficiency of EC1T10-SiC was 43.11 % higher than the photocatalytic efficiency of EC0T10-SiC after UV irradiation for 75 min. Quenching experiments show that superoxide radicals (O2−) are the main reactive species in this process. A possible enhanced mechanism was proposed based upon oxidation layer thinning that favors photogenerated electron transport and polar centers (>Cδ+=Oδ-) favorable for photogenic electron migration. This study presents a simple method for controlling the surface structure of silicon carbide to achieve excellent photocatalytic performance. This method is environmentally friendly, easy to implement, and suitable for practical applications.

Evaluation of natural ageing responses on Burmese amber durability by FTIR spectroscopy with PLSR and ANN models

Amber ageing is an inevitable process, which is very important in precious organic gemstone relics protection. In order to explore the mechanism of amber ageing and estimate the durability of Burmese amber, this research investigates the changing spectral features of Burmese ageing amber via Fourier Transform Infrared Spectroscopy (FTIR) and solid 13C Nuclear Magnetic Resonance spectroscopy (NMR) and develops the regression models for its micro-hardness by micro-FTIR spectra. The Partial Least Squares Regression (PLSR) and Artificial Neural Networks (ANN) methods as well as Competitive Adaptive Reweighted Sampling (CARS) algorithm for wavelength variables selection have been applied to predict and assess the Vickers hardness of amber samples with different ageing degrees. As a result, the FTIR and the solid 13C NMR spectra reveal that the contents of CO groups (of esters) increase substantially, and which of the other oxygenic groups (CO (of acids), COC, COCC) increase modestly in amber ageing. When comparing with the results of four different models (PLSR, ANN, CARS-PLSR and CARS-ANN), the CARS-PLSR model obtained the optimal results as follows: the squared correlation coefficient of calibration(R2cal) is 0.9230 and the root mean square error of calibration (RMSEC) is 1.2977 HV; the squared correlation coefficient of prediction (R2pre) is 0.7762 and the root mean square error of prediction (RMSEP) is 2.2208 HV. The overall results sufficiently demonstrate that FTIR spectroscopy technique coupled with appropriate chemometrics methods are very promising tools to estimate and predict the hardness property of Burmese ageing amber.

Effect of HF etching on titanium carbide (Ti3C2Tx) microstructure and its capacitive properties

Two-dimensional multi-layered microstructure generated by hydrofluoric acid etching is essential for the high capacitance MXenes. However, the mechanisms dictating the formation, evolution and properties of MXenes during etching remain elusive due to the lack of direct observation. Herein, using ex-situ scanning electron microscopy combined with high resolution transmission electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy, we have revealed the fine variation of microstructure and properties of multi-layered titanium carbide Ti3C2Tx etched for different time. The results show that the laminar cracks always formed from the first initial laminar crack at the edge site of the outermost side of the Ti3AlC2 particle, which induces continuous nucleation of other laminar cracks in the nearby area. The early laminar cracks undergo growth accompanying with increased macro-layer density of Ti3C2Tx and the Al(F,O,C)3 precipitation in subsequent etching process. The formation of laminar cracks is revealed to be correlated with the release of local internal stress in Ti3AlC2. In addition, it is found that there are significant changes of Ti valence state, CC and Ti-C bonding as well as Ti-F, CO and Al-O surface groups during etching. Maximum specific capacitance coincides with maximum lattice parameter c of Ti3C2Tx and maximum number of macro-layers, while over-etching produces in-plane microcracks, Ti dissolution, and reduced specific capacitance. The results provide important insight to facilitate optimal synthesis of this material.

Efficient Pd on carbon catalyst for ammonium formate dehydrogenation: Effect of surface oxygen functional groups

Formate solution is a promising liquid organic hydrogen carrier but suffers from kinetic challenges. This study investigates the kinetics of the surface-functionalized Pd on carbon catalysts for formate dehydrogenation and the impact of O-functional groups. The fraction of the distinguished O-functional groups was modulated by the different concentrated HNO3 solutions treatment or by H2 reduction. This study shows that the O-functional groups play critical roles in dispersing Pd nanoparticles and decreasing the activation energy for dehydrogenation. Density functional theory (DFT) calculation reveals that most O-functional groups enhance formate adsorption on the Pd active site. However, the existence of CO groups consumes reducing agents and hinders the formation of metallic Pd. The electron transfer from Pd to oxygen functional groups is unfavorable to dehydrogenation. The as-prepared Pd5/re-ACA (reduced activated carbon washed by acid) exhibited significant activity with a higher turnover frequency of 13,511 h−1 than commercial Pd/C.

Fetal Programming of the Endocrine Pancreas: Impact of a Maternal Low-Protein Diet on Gene Expression in the Perinatal Rat Pancreas.

In rats, the time of birth is characterized by a transient rise in beta cell replication, as well as beta cell neogenesis and the functional maturation of the endocrine pancreas. However, the knowledge of the gene expression during this period of beta cell expansion is incomplete. The aim was to characterize the perinatal rat pancreas transcriptome and to identify regulatory pathways differentially regulated at the whole organ level in the offspring of mothers fed a regular control diet (CO) and of mothers fed a low-protein diet (LP). We performed mRNA expression profiling via the microarray analysis of total rat pancreas samples at embryonic day (E) 20 and postnatal days (P) 0 and 2. In the CO group, pancreas metabolic pathways related to sterol and lipid metabolism were highly enriched, whereas the LP diet induced changes in transcripts involved in RNA transcription and gene regulation, as well as cell migration and apoptosis. Moreover, a number of individual transcripts were markedly upregulated at P0 in the CO pancreas: growth arrest specific 6 (Gas6), legumain (Lgmn), Ets variant gene 5 (Etv5), alpha-fetoprotein (Afp), dual-specificity phosphatase 6 (Dusp6), and angiopoietin-like 4 (Angptl4). The LP diet induced the downregulation of a large number of transcripts, including neurogenin 3 (Neurog3), Etv5, Gas6, Dusp6, signaling transducer and activator of transcription 3 (Stat3), growth hormone receptor (Ghr), prolactin receptor (Prlr), and Gas6 receptor (AXL receptor tyrosine kinase; Axl), whereas upregulated transcripts were related to inflammatory responses and cell motility. We identified differentially regulated genes and transcriptional networks in the perinatal pancreas. These data revealed marked adaptations of exocrine and endocrine in the pancreas to the low-protein diet, and the data can contribute to identifying novel regulators of beta cell mass expansion and functional maturation and may provide a valuable tool in the generation of fully functional beta cells from stem cells to be used in replacement therapy.

A ZIF-8-derived copper-nitrogen co-hybrid carbon catalyst for peroxymonosulfate activation to degrade BPA

A series of copper-nitrogen co-hybrid porous carbon catalysts were prepared by pyrolysis of copper-doped ZIF-8 in argon atmosphere. Both the precursors and the corresponding pyrolysis products retained the polyhedral morphology of ZIF-8. The catalytic performance of the catalysts obtained at different Cu doping levels and pyrolysis temperatures for PMS activation was compared by bisphenol A (BPA) degradation experiment. Among them 5%Cu-NC(8) catalyst obtained by pyrolysis of 5%Cu-ZIF-8 at 950 °C showed the best catalytic performance. The catalytic mechanism of PMS activation catalyzed by 5%Cu-NC(8) was analyzed by quenching experiment, ESR and XPS. The degradation pathways of BPA in 5%Cu-NC(8)/PMS system were proposed on the basis of LC-MS analyses. Pyridine N (including Cu–N), graphite N, CO group and the valence change of Cu were recognized as the catalytic active sites for 5%Cu-NC(8). Both free radical and non-free radical processes were involved in BPA degradation, and singlet oxygen (1O2) was identified to be the main active substance. The stable performance and low Cu leaching rate in recycling experiment indicated that 5%Cu-NC(8) had good reusability and stability. This study provided a new insight for the design of heterogeneous copper-nitrogen co-hybrid carbon catalysts.

Mechanochemistry assisted surface chemical modification on hard carbon for sodium storage: Size effect

Mechanochemical modification has been proved to be an effective and green method for carbon materials in the field of electrochemical energy storage. However, the research on the size effect during mechanochemical process seems still in blank for carbon materials. In this work, the size effect on the variations of the structural and electrochemical properties after mechanochemical treatments is studied through hard carbon spheres (CSs) with sizes of 170 nm, 492 nm and 0.9 μm. The size effect during the treatments affects the specific surface areas, pore structures, defects, functional groups, and the sodium storage properties. It comes as a surprise to find that parts of CO groups are converted to CO groups directionally. Significantly, the content variation of oxygen functional groups of large-sized CSs is more drastic, causing larger fluctuation in electrochemical performance. Interestingly, the performance improvement of the large-sized CSs is 18.4 % which is higher than that of medium-sized CSs (10.7 %) and small-sized CSs (9.3 %). The present work has provided a new scientific significance for carbon materials from lab-scale to industrial-scale in the field of battery electrode.

Time-resolved FTIR difference spectroscopy for the study of photosystem I with high potential naphthoquinones incorporated into the A1 binding site

Time–resolved step-scan Fourier transform infrared difference spectroscopy has been used to study cyanobacterial photosystem I photosynthetic reaction centers from Synechocystis sp. PCC 6803 (S6803) with four high-potential, 1,4-naphthoquinones incorporated into the A1 binding site. The high-potential naphthoquinones are 2-chloro-, 2-bromo-, 2,3-dichloro- and 2,3-dibromo-1,4-naphthoquinone. “Foreign minus native” double difference spectra (DDS) were constructed by subtracting difference spectra for native photosystem I (with phylloquinone in the A1 binding site) from corresponding spectra obtained using photosystem I with the different quinones incorporated. To help assess and assign bands in the difference and double difference spectra, density functional theory based vibrational frequency calculations for the different quinones in solvent, or in the presence of a single asymmetric H– bond to either a water molecule or a peptide backbone NH group, were undertaken. Calculated and experimental spectra agree best for the peptide backbone asymmetrically H– bonded system. By comparing multiple sets of double difference spectra, several new bands for the native quinone (phylloquinone) are identified. By comparing calculated and experimental spectra we conclude that the mono-substituted halogenated NQs can occupy the binding site in either of two different orientations, with the chlorine or bromine atom being either ortho or meta to the H– bonded CO group.