Narrow Results

A new apparatus is made to prepare a uniform and thin target for PIXE analysis by atomizing sample solution hydrolyzed with nitric acid at 105ºC for 2 hrs. When concentration of NIST Bovine Liver (SRM 1577b) is determined, values of almost all elements heavier than Na, except for Cl and Br, which are volatile under acidic condition, are roughly same as those certified by NIST.

In this paper, large-scale Bi(2201) nanofilm was mechanically exfoliated. The thin film Bi(2201) was characterized by means of optical image and XRD spectrum analysis. AFM is used to study the stability of Bi(2201) thin film. We found that the Bi(2201) nanofilm was less sensitive to CO₂ while it extremely got affected by humidity. With the rise in the humidity, the hydrolytic speed of Bi(2201) film was greatly increased. When the relative humidity of the air is lower than 20%, the Bi(2201) thin film can be stable in two days. However, when the relative humidity is about 90% RH, Bi(2201) film will be hydrolyzed in few minutes.

ZnO with 2D flower-like and 1D rod shape were obtained from simple and rapid hydrolysis of Zn nanopowder. The Zn nanopowders were incorporated into distilled water with acetic acid and then the solution was stirred at 60°C for 8 h. The nanoflower-like and rod shape were formed without any surfactant. It seems that the acetic acid played a role of controlling PH and etching the oxide layer on the surface of metal nanopowders to enhance rapid reaction with distilled water. X-ray diffraction patterns for all samples exhibited that the resultant precipitates were completely transformed to ZnO powder. It is clearly observed that the morphological changes of ZnO with reaction time in aqueous solution follows chestnut bur → flower → tetrahedron → rod sequences during the hydrolysis reaction.

Titanium tetrachloride was used to synthesize titanium dioxide emulsion by the hydrolysis process. The semiconductor was deposited on raw unglazed ceramic and silicon substrate by the reactive chemical spraying process. The experimental conditions were chosen to ensure film adhesion. Obtained films were calcined at different temperatures ranging from 600^∘C to 680^∘C and characterized by X-ray diffraction, atomic force microscopy, optical measurement, contact angle measurement, and scratch test. The photocatalytic test was carried out under UV irradiation using an azo dye. The silicon substrate allowed to show the film structure. The AFM observation indicated that film roughness increased from 12nm to 32nm. Roughness growth corresponds to a large active surface and enhanced photocatalyst activity. During the photocatalyst test under UV irradiation, the sample calcined at 660^∘C shows the best result with a degradation efficiency of 140mg${\text{m}}^{-2}$${\text{h}}^{-1}$. The same sample was characterized by hydrophilic behavior and adhesion strength.

Synthesis of ZnO nanoparticle and the hydrolysis of p-Acetoxynitrobenzene to p-Nitrophenol (p-NP) under aqueous phase conditions in the presence of ZnO nanoparticle has been carried out. Zinc oxide (ZnO) nanoparticles (NPs) are prepared by using simple precipitation method. Ammonia is used as a precipitating agent and ZnCl${}_2\cdot 4$H₂O as a starting material. The obtained ZnO NPs are characterized by using different techniques namely XRD, TGA/DTA, TEM, FT-IR, magnetic measurements and BET surface area analysis. ZnO NPs are evaluated for their catalytic properties in hydrolysis of p-Acetoxynitrobenzene to p-Nitrophenol (p-NP) under aqueous phase conditions. The effect of temperature and concentration has also been studied for the catalytic hydrolysis. This is to emphasize that the method used to synthesize these NPs is much simple and fiscal. The obtained ZnO NPs work as a good catalyst for the above conversion and are of low cost and easy to synthesize.

Hydrolysis of trans-dichloro(ammine)(quinoline)platinum, a novel potential anticancer drug, is believed to be the key activation step before the drug reaches its intracellular target DNA. To obtain an accurate hydrolysis mechanism for this nonclassical class of square-planar Pt(II) complex, five different models were used at the experimental temperature with the solvent effect B3LYP/PCM using hybrid density functional theory. The stationary points on the potential energy surfaces for the first and second hydrolysis steps, proceeding via a five-coordinate trigonal-bipyramidal (TBP)-like structure of transition state, were fully optimized and characterized. The most remarkable structural variations in the hydrolysis process were found to occur in the equatorial plane of the TBP-like structures of the intermediates and transition states. It was found that the explicit solvent effect originating from the inclusion of extra water molecules into the system is significantly stronger than those arising from the bulk aqueous medium, especially for the first aquation step, which emphasizes the use of appropriate models for these types of problems. The results give detailed energy profiles for the mechanism of hydrolysis of trans-dichloro(ammine)(quinoline)platinum, which may assist in understanding the reaction mechanism of the drug with DNA target and in the design of novel platinum-based anticancer drugs with trans geometries.

The hydrolysis process of Ru(III) complex (HL)[trans-RuCl₄L(dmso-S)] (L=4-amino-1,2,4-triazole) (1), a potential antitumor complex similar to the well-known antitumor agent (ImH)[trans-RuCl₄(dmso-S)(Im)](NAMI-A), was investigated using density functional theory (DFT) with the conductor-like polarizable continuum model (CPCM). The structural characteristics and the detailed energy profiles for the hydrolysis processes of this complex were obtained. For the first hydrolysis step, complex 1 with 4-amino-1,2,4-triazole ligand shows much faster aquation than NAMI-A with imidazole ligand and complex 2 with 4H-1,2,4-triazole ligand, and such a calculated result is in good agreement with the experimental one. For the second hydrolysis step, the formation of cis-diaqua products is found to be thermodynamically preferred over the trans isomers. In addition, on the basis of the analysis of electronic characteristics of species in the hydrolysis process, the trend in abilities (A) of hydrolysis products attacked nucleophilicly by pertinent biomolecules is revealed. These theoretical results will help in understanding the action mechanism of this potential Ru(III) drug with pertinent biomolecular targets.

As the only metabolizing enzyme for the degradation of second messenger cAMP and cGMP, phosphodiesterase (PDE) has been the clinical target of various human diseases. But the hydrolysis procedure of PDE is still unclear. To investigate the mechanism of PDE catalysis, three types of PDE (PDE4d, PDE5a and PDE10a) were selected and studied by using molecular dynamics (MD) simulation and quantum mechanics (QM) calculation methods. MD Simulation results indicate that different PDEs share a similar hydrolysis area in the active sites, and the phosphate parts of cyclic nucleotides take the same orientation and are partly surrounded by water molecules. Based on the statistical data of MD simulation, the QM calculation models were built. The calculation results indicate that in aqueous solution, the nucleophile hydroxide ion that attacks the phosphor atom of the cyclic nucleotide in the hydrolysis may migrate between the two metal ions in the active site. To help the ring-open reaction, it is the water molecule that provides proton to the O3′ atom of cyclic nucleotide, and generates another hydroxide ion complexed with the metal ion.

The decarboxylation of pyrrole-2-carboxylic acid comprises the addition of water to the carboxyl group and the C–C bond cleavage leading to the protonated carbonic acid. Herein possible concerted and stepwise mechanisms for the C-protonated and O-protonated pathways were extensively investigated by using the cluster-continuum model. The calculated results indicate that the initial hydration or the nucleophilic attack of water at the carbonyl group of both C- and O-protonated derivatives is the rate-determining step for the overall reaction, and the O-protonated pathway will dominate the whole reaction. The predicted activation Gibbs energies for the overall reaction initialized by the O-protonated species fall in the range of 83.3 ∼ 123.0 kJ/mol, showing good agreement with experimental values of 91.6 ∼ 101.3 kJ/mol. On the basis of extensive calculations, the remarkable dependence of the predicted mechanisms and thermodynamic values on the number of explicit water molecules in the cluster-continuum model was discussed.

Oseltamivir (OTV) is widely used in the treatment of both influenza virus A and B infections. Additionally, OTV is an effective antiviral drug in treating the 2009 A (H1N1) influenza virus. Clinical studies concluded that OTV is readily extensively converted to the active carboxylate metabolite after oral administration. In order to investigate the metabolism mechanism of OTV, we carried out density functional theory (DFT) quantum mechanical calculations. The molecule orbital (MO) theory and natural population analysis (NPA) were also employed to help understanding the reaction mechanism. All possible reaction pathways for OTV metabolism are considered, involving hydrolysis of ester and amide. Two mechanisms were considered in this work, viz. concerted mechanism and stepwise mechanism. Our results indicate the stepwise mechanism is more favorable in both hydrolysis reactions and the rate-determining stage is the formation of the tetrahedral intermediate. In addition, the hydrolysis reactions can be assisted by substrate NH2 group and solvent water molecules. The substrate-assisted mechanism for the formation of the carboxylate metabolite is the most favorable one.

The living cationic polymerization of 4-[2-(tert-butyldimethylsiloxy)ethyl]styrene (TBDMES) was studied in methylcyclohexane (MeChx)/methylchloride (MeCl) (50/50 V/V) solvent mixture at –80°C. The initiator 1,1-diphenylethylene (DPE) capped 2-chloro-2,4,4-trimethylpentane (TMPCl) was formed in situ in conjunction with titanium tetrachloride (TiCl₄). The Lewis acidity of TiCl₄ was decreased by the addition of titanium(IV) isopropoxide (Ti(OiPr)₄) to accomplish living polymerization of TBDMES. Hydrolysis of poly(TBDMES) in the presence of tetra-butylammonium fluoride yielded poly[4-(2-hydroxyethyl)styrene] (poly(HOES)). FT-IR, NMR and DSC demonstrated the hydrolysis was complete.

Various chlorophyll and bacteriochlorophyll derivatives possessing a magnesium or zinc atom at the central position and a free carboxylic acid group at the C17${}^{\mathrm{\text{2}}}$-position, also known as (bacterio)chlorophyllides, were synthesized through a combination of organic synthesis techniques and enzymatic steps. The semi-synthetic (bacterio)chlorophyllides were purified and analyzed using reversed-phase high-performance liquid chromatography with UV-vis spectroscopy and mass spectrometry. These free propionic acid-containing chlorophyllous pigments can be useful research materials for the study of (bacterio)chlorophyll metabolisms.

The heme oxygenase (HO) enzyme is a free heme protein that binds to heme in the body. Heme acts as both a cofactor and a substrate in this enzyme. The catabolism of heme into biliverdin, monoxide carbon, and free-iron, catalyzed by heme oxygenase via three consecutive oxygenation steps, in which the heme group functions as the prosthetic group as well as the substrate. Investigations of the reactions of the peripheral substituent on the heme ring with 5-oxaporphyrin iron complexes (verdohemes) have been assumed to provide models and largely unknown for the primary step in the hydrolysis of verdohemes. In this work, a theoretical kinetics and thermodynamics study of the degradation reactions of verdohemes was performed, and calculations show that the $\mathrm{\Delta }{G}_{\text{reaction}}$ in the hydrolysis of verdohemes with non-peripheral substituents is more negative than hydrolysis of verdohemes with peripheral substituents. In other words, the hydrolysis of verdohemes with non-peripheral substituents is more energy-efficient than verdohemes with a peripheral substituents. Equilibrium constant calculations show that hydrolysis of verdohemes with non-peripheral substituents is much faster than that of verdohemes with peripheral substituents, which is due to a more convenient nucleophilic attack on the cationic ring than the anionic ring. To acquire a good molecular understanding, peripheral substituent effects on the hydrolysis of verdoheme’s inhibitory role was studied using the DFT method.

Generation of hydrogen by sodium borohydride solution had attracted lots of attention. A serial of nanosized NiB catalysts were prepared using the chemical reduction method through introducing AlCl₃ into the preparation. Catalytic performance of NiB catalysts were investigated in the hydrolysis of alkaline NaBH₄ solution. The catalysts were characterized by X-ray diffraction (XRD), N₂ adsorption, Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The results showed that NiB catalysts possessed amorphous alloy structure, and the particle size could be adjusted by the AlCl₃ amount. Catalytic performance showed that NiB catalyst with smaller particle size had much higher activity. The NiB catalyst also displayed high stability, the catalytic activity could retain about 84% of its initial value after four cycles.

A cobalt (Co)/graphene sheets (GRs) composite was synthesized via a one-pot chemical method. The composite shows high saturation magnetizations (M_s), which leads it to be conveniently separated from aqueous solution by an external magnetic field. Compared to the pure Co and some references, the catalytic activity of the as-obtained composite was significantly enhanced for the generation of H₂ gas by hydrolysis of NaBH₄ solution. Effects of NaBH₄ initial concentration, the composite and reaction temperature on the H₂ generation rate were investigated. The H₂ generation rate is independent with the initial NaBH₄ concentration, increased with the reaction temperature increasing. The composite can be continuously used several times with about the same catalytic activity.

Hydrogen generation from the catalytic hydrolysis of sodium borohydride has many advantages, and therefore, significant research has been undertaken on the development of highly efficient catalysts for this purpose. In our present work, Co₃O₄ nanowires were successfully synthesized as catalyst precursor by employing SBA-15 as a hard template. For material characterization, high-resolution transmission electron microscopy (HRTEM), powder X-ray diffraction (XRD), fourier-transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), inductively coupled plasma-atomic emission spectroscopy (ICP-AES) and N₂ adsorption isotherms were employed, respectively. To measure the catalyst activity, typical water-displacement method was carried out. Using a reaction solution comprising 10wt.% NaBH₄ and 2wt.% NaOH, the hydrogen generation rate (HGR) was observed to be as high as 7.74L min${}^{-1}$ g${}^{-1}$ at 25${}^{\circ }$C in the presence of Co₃O₄ nanowires, which is significantly higher than that of CoB nanoparticles and commercial Co₃O₄ powder. Apparent activation energy was calculated to be 50.9kJ mol${}^{-1}$. After recycling the Co₃O₄ nanowires six times, HGR was decreased to be 72.6% of the initial level.

The worldwide application of hydrogen energy greatly promotes the development of NaBH₄ hydrolysis for hydrogen production, particularly the study of hydrolysis catalysts. In this work, an anatase TiO₂-supported ruthenium nanocatalysts (i.e., Ru/TiO₂) was facilely prepared by photocatalytic reduction without the use of any chemical reducing reagents. The Ru catalysts had an average particle size of approximately 2.2nm and were uniformly distributed. The Ru/TiO₂ was characterized by HRTEM, EDS, XRD, XPS and ICP-AES, respectively, and evaluated by classical water-displacement method. Using a 5wt.% NaBH${}_4+2$wt.% NaOH solution, hydrogen generation (HG) rate was as high as 38.6Lmin${}^{-1}$g${}_{\mathrm{\text{Ru}}}^{-1}$ at 30^∘C, and apparent activation energy was calculated to be 55.9kJmol${}^{-1}$. Compared with similar Ru-based catalysts reported in literature, the Ru/TiO₂ prepared in this work shows higher catalytic activity and lower apparent activation energy. After recycling for five times, the HG rate remained to be 91.7% of the initial level.

For hydrogen generation from sodium borohydride hydrolysis, high-efficient catalyst precursor of porous Co₃O₄ nanoplatelets was successfully achieved by a combined process of hydrothermal synthesis and calcination treatment. Effects of calcination temperature on catalyst morphology and activity were mainly investigated, and the optimal condition was established. Using a reaction solution comprising 10wt.% NaBH₄ and 2wt.% NaOH, the porous Co₃O₄ nanoplatelets exhibited a maximum hydrogen generation rate up to 19.52Lmin${}^{-1}$ g${}^{-1}$ at the temperature of 25${}^{\circ }$C, which was much higher than similar Co₃O₄ catalyst precursors and noble metal catalysts in literature.

Lignocellulosic biomass (LCB) represents abundant biomass that is economically feasible and environmentally sustainable to produce biofuels and bioproducts. Despite these lucrative advantages, LCB faces logistical and technological challenges in its utilization. Low bulk density and high moisture content hinder the biomass’s efficient transportation and storage. Densification has become an essential step for efficient transport, storage, and utilization of biomass, pelletization being one of the most common densification methods. Pellets (and other densification techniques) have been studied in great detail for the thermochemical conversion of biomass. However, the extent of knowledge of its effect on sugar yields during biochemical conversions is limited. This chapter summarizes the densification methods used for biomass for biochemical conversion and their possible merits and limitations.

The sun is the only source of renewable energy available to us, if geothermal energy is not taken into account. In the form of radiation (UV light, visible light, infrared light, Section 1.1) it sends us annually 178,000 terawatts (1 TW = 10¹² W; unit of power 1 W = 1 J s^–1 = 859.85 calories per hour), that is to say 15,000 times the energy consumed annually by humanity. Only 0.1% of the solar energy received by planet Earth is converted into plant biomass, i.e. 100 × 10⁹ tons per year which corresponds to ca. 180 × 10⁹ tons per year of CO₂ captured from the atmosphere. This CO₂ returns to the biosphere after the death of the plants. Consumption of fossil carbon emits ca. 35 × 10⁹ tons of CO₂ yearly. Biomass is the material produced by all living organisms (plants, animals, microorganisms, fungi)…