Low Bond Energy Research Articles

Hydrogenation/Deoxygenation (H/D) Reaction of Furfural-Acetone Condensation Product using Ni/Al2O3-ZrO2 Catalyst

The catalytic hydrogenation/deoxygenation (H/D) reaction was carried out using Ni/Al 2 O 3 -ZrO 2 catalyst. The 10% (wt/wt) of Ni were impregnated on Al 2 O 3 -ZrO 2 (10NiAZ) by wet impregnation method followed by calcination and reduction. X-Ray diffraction analysis showed that Nideposited on the surface, with specific surface areas (S BET ) was 48.616 m 2 /g. Catalyst performance were evaluated for H/D reaction over furfural-acetone condensation products, mixture of 2-(4-furyl)-3-buten-2-on and 1,5-bis-(furan-2-yl)-pentan-3-one. The reaction was carried out in a batch, performed at 150°C for 8 hours. The H/D reaction gave alkane derivatives C8 and C10 by hydrogenation process followed by ring opening of furan in 15.2% yield. While, oxygenated product C10-C13 were also detected in 17.2% yield. The increasing of pore volume of 10NiAZ might enhance catalyst activity over H/D reaction. The alkene C=C bond was easy to hydrogenated under this condition by the lower bond energy gap.

Excess Coalbed Methane Production Mechanism in the Process of Coal Tectonic Deformation

Source and occurrence of Excess Coalbed Methane is a long-term concern research topic in Coal Geology and Structural Geology. Since it is essential to understand the outburst mechanism of coal gas, and to support the coalbed methane development projects as the theoretical basis. We found in the study that, huge imparity is behind the evolutionary trend on molecular structure and the mechanism of influence from different deformation. The thesis demonstrates its probable routes of gas evolution according to distinct deformation mechanisms of coal. In the role of brittle deformation mechanism, a rapidly formed advantage rupture surface along with sliding motion from which has worked on coal. As another result, mechanical energy has transformed into friction and kinetic energy during the process. Kinetic energy increases simultaneously, which brings some results, that the new generated gas molecule. While the chemical structure of coal remains in a steady-state and do not react easily an outburst with gas. Mechanical energy turns into strain energy through its ductile deformation mechanism. The dislocation or lamellar slip made disordered between the constitutional units of aromatic rings and aromatic lamellas, as soon as secondary structural defects created. On another hand, molecular motion accelerates and splits off the small molecular on the side chain, due to the dissociation of aromatic nucleus; CH4 gas molecular was generated and placed in the secondary structural defect of coal, along with a great deal of strain energy in non-steady-state. By breaking away the balance maintaining terms, huge strain energy releases suddenly, small moleculars are free from the secondary structure defect, react outburst with gas. Furthermore to extend the discussion of the conventional physical ideas on coal absorb gas, according to the phenomenon of exceeded CBM, the gas molecular has a significant chance existing in a low bond energy of chemical bonds of coal structure.

SKRINING IN SILICO POTENSI SENYAWA ALLICIN DARI ALLIUM SATIVUM SEBAGAI ANTIPLASMODIUM

Allicin compound (2-propene-1- sulphinothioat acid S-2-propenyl ester) is known to have potential as antiplasmodium in vitro. However, the inhibitory activity mechanism of Allicin to plasmodium is still unknown. In this research, we determined the inhibitory activity of Allicin in silico. Identification of physicochemical properties of Allicin compound and two Allicin derivatives, Alc1, Alc2 and Ac2Alc3 were also conducted.. Furthermore, analysis of drug-likeness and adsorption-distribution-metabolism-excretion (ADME) were carried out on the Allicin compound and its derivatives to find the potential of these compounds as drug candidates. In determining the specific interaction, we utilized molecular docking analysis between Allicin and its derivatives against a protein target Cysteine Protease (SP). Molecular docking results showed that Allicin derivative, Alc2 (S-prop-2-en-1-yl 3-methylbut-2-ene-1-sulfinothioate, C10H18OS2) has better potential as inhibitors than Allicin, based on the lower bond energies and the inhibition constants, thus Alc2 can be used as an antiplasmodium agent candidate.Keywords: Allicin, Allicin derivatives, drug likeness, ADME, molecular docking

Effects of CeO2 and Y2O3 on the interfacial diffusion of Ti/Al2O3 composites

Different content of CeO2 and Y2O3 (2 vol.% and 3 vol.%) were used as additives to restrain the Ti/Al2O3 interfacial reaction by the vacuum hot pressing sintering. Results showed that rare earth oxides effectively reduced the thicknesses of the reaction layers. Specifically, when 3 vol.% CeO2 was added, the thickness reached the minimum value of 38.4 μm at 1350 °C. Based on the analysis of XRD and SEM, the positive effect of the rare earth oxides could be ascribed to their combination with Al2O3 and pinning effect at the grain boundary. Furthermore, the superior effect of CeO2 to Y2O3 was explained by the reasonable mechanism which was focused on its smaller ionic radius, lower bond energy and stronger ability of combining with Al2O3. The diffusion mechanisms of various elements at the interfaces were also discussed in details.

MOFs as sacrificial templates for preparation of nanoporous carbon materials and their applications

In recent years, nanoporous materials have attracted much attention owing to their high specific surface areas and narrow pore-size distribution. These materials have been widely used in gas storage, gas separation, catalysis and electrochemistry. Nanoporous carbon materials (NPCs), a sub-family of nanoporous materials, have been one type of the most popular functional materials. Enormous efforts have been made in the preparation of NPCs with various pore structures. Although many new NPCs have been prepared, most of them have mesoporous/macroporous/disordered structures, which limit their performance as functional materials. Therefore, the development of convenient synthetic methods to NPCs with narrower pore size at a microporous level is still a significant challenge. More recently, a novel, efficient synthetic method, thermal decomposition of metal-organic frameworks (MOFs), has been developed to obtain well-defined ordered NPCs with narrow pore sizes. MOFs have emerged as a new class of porous materials that are assembled with metal ions and organic ligands. Owing to their ordered structures, high surface areas, and large pore volumes, MOFs have been widely utilized in a variety of fields such as heterogeneous catalysis, electrochemistry, gas adsorption, and sensors. Considering the low coordination bond energy between the ligands and metal ions of MOFs, the stability of MOFs is normally lower than the traditional porous materials. MOFs have been considered as alternative precursors for the preparation of new metal oxides or carbon nanomaterials by pyrolysis. This article briefly reviews the recent progress in the preparation of these novel MOF-derived nanoporous carbons. We describe two methods to synthesize MOF-derived nanoporous carbons. One is one-step direct pyrolysis of MOFs for synthesis of nanoporous carbons. The other is introduced carbon sources into the micropores of MOFs before calcination. Furfuryl alcohol (FA), glycerol, carbon tetrachloride and ethylenediamine, and phenolic resin have been successfully employed as the carbon sources. In this review, MOFs-derived materials are classified to three species based on calcination atmosphere and metal ions, i.e., nanoporous carbons, metal/metal oxide nanoparticles embedded in a carbon matrix, and metal/metal oxide nanoparticles. At the same time, we also elaborate the applications of the porous carbon materials that are derived from MOFs as the sacrifice templates systematically. Some promising applications in, such as energy and environment-related areas, and the outlook of such types of materials are also discussed.

Highly Selective Dissociation of a Peptide Bond Following Excitation of Core Electrons.

The controlled breaking of a specific chemical bond with photons in complex molecules remains a major challenge in chemistry. In principle, using the K-edge absorption of a particular atomic element, one might excite selectively a specific atomic entity in a molecule. We report here highly selective dissociation of the peptide bonds in N-methylformamide and N-methylacetamide on tuning the X-ray wavelength to the K-edge absorption of the atoms connected to (or near) the peptide bond. The high selectivity (56-71%) of this cleavage arises from the large energy shift of X-ray absorption, a large overlap of the 1s orbital and the valence π* orbital that is highly localized on a peptide bond with antibonding character, and the relatively low bond energy of the peptide bonds. These characteristics indicate that the high selectivity on bond dissociation following core excitation could be a general feature for molecules containing peptide bonds.

Photoreduction of CO2 on BiOCl nanoplates with the assistance of photoinduced oxygen vacancies

CO2 photoreduction by semiconductors is of growing interest. Fabrication of oxygen-deficient surfaces is an important strategy for enhancing CO2 photoreduction activity. However, regeneration of the oxygen vacancies in photocatalysts is still a problem since an oxygen vacancy will be filled up by the O atom from CO2 after the dissociation process. Herein, we have fabricated highly efficient BiOCl nanoplates with photoinduced oxygen vacancies. Oxygen vacancies were easily regenerated by light irradiation due to the high oxygen atom density and low Bi-O bond energy even when the oxygen vacancies had been filled up by the O atom in the photocatalytic reactions. These oxygen vacancies not only enhanced the trapping capability for CO2, but also enhanced the efficiency of separation of electron-hole pairs, which resulted in the photocatalytic CO2 reduction under simulated solar light. Furthermore, the generation and recovery of the defects in the BiOCl could be realized during the photocatalytic reduction of CO2 in water. The existence of photoinduced defects in thin BiOCl nanoplates undoubtedly leads to new possibilities for the design of solar-driven bismuth based photocatalysts.

Diffusion of oxygen in amorphous Al2O3, Ta2O5, and Nb2O5

The self-diffusivity of oxygen in amorphous Al2O3 (a-Al2O3), a-Ta2O5, and a-Nb2O5 was investigated along with structural analysis in terms of pair distribution function (PDF). The low activation energy, ∼1.2 eV, for diffusion in the oxides suggests a single atomic jump of oxygen ions mediated via vacancy-like defects. However, the pre-exponential factor for a-Ta2O5 and a-Nb2O5 with lower bond energy was two orders of magnitude larger than that for a-Al2O3 with higher bond energy. PDF analyses revealed that the short-range configuration in a-Ta2O5 and a-Nb2O5 was more broadly distributed than that in a-Al2O3. Due to the larger variety of atomic configurations of a-Ta2O5 and a-Nb2O5, these oxides have a higher activation entropy for diffusion than a-Al2O3. The entropy term for diffusion associated with short-range structures was shown to be a dominant factor for diffusion in amorphous oxides.

Enhancement of styrene removal using a novel double-tube dielectric barrier discharge (DDBD) reactor

Abstract A novel double-tube dielectric barrier discharge (DDBD) reactor was established by us to degrade styrene. The DDBD reactor contains two discharge zones with one power supply, the outer tube zone with low discharge energy and the inner tube zone with high discharge energy. The gas first flows into the outer tube zone and then flows into the inner tube zone, at last flows out from the inner tube zone. Compared with traditional single-tube dielectric barrier discharge (SDBD) reactor, the DDBD reactor shows the following advantages: (a) the energy utilization efficiency can be improved because the low bond energy groups in styrene can be destroyed first in outer discharge zone by weak discharge energy and the high bond energy groups such as aromatic rings can then be concentrated destroyed in inner discharge zone by high discharge energy; (b) the high mineralization efficiency results in no oil-like byproducts aggregated on the surface of reactor surface; (c) the double dielectric layers are protected from penetration. The diameters of outer and inner tubes were optimized and the DDBD reactor with 25 mm outer tube and 6 mm inner tube exhibited the best styrene mineralization efficiency. Compared with SDBD reactor with the same outer tube diameter, the selectivities of CO and CO 2 were improved by 40% with the styrene concentration of 2000 mg m −3 at the applied voltage of 11 kV. Meanwhile there was no any oil-like byproducts observed aggregated on outer tube wall, inner tube outlet and the electrode after 6 h treatment. The applied voltage, oxygen content, discharge length and relative humidity were optimized in this research and the byproducts of O 3 and NO x were also detected and discussed.

Sulfide Solid Electrolyte with Favorable Mechanical Property for All-Solid-State Lithium Battery

All-solid-state secondary batteries that employ inorganic solid electrolytes are desirable because they are potentially safer than conventional batteries. The ionic conductivities of solid electrolytes are currently attracting great attention. In addition to the conductivity, the mechanical properties of solid electrolytes are important for improving the energy density and cycle performance. However, the mechanical properties of sulfide electrolytes have not been clarified in detail. Here, we demonstrate the unique mechanical properties of sulfide electrolytes. Sulfide electrolytes show room temperature pressure sintering. Ionic materials with low bond energies and a highly covalent character, which is promising for achieving a high ionic conductivity, tend to be suitable for room-temperature processing. The Young's moduli of sulfide electrolytes were measured to be about 20 GPa, which is an intermediate value between those of typical oxides and organic polymers.

Cross sections of 43Sc, 44Sc, 46Sc isotopes formed in the 45Sc + 3He reaction

Reactions 45Sc(3He, αn)43Sc, 45Sc(3He, α)44Sc and 45Sc(3He, 2p)46Sc in the 3He energy range of 5 to 24 MeV are investigated in experiments performed with a 3He ion beam during the irradiation of U-120M cyclotron scandium targets. Activation is used to determine the yield of nascent Sc isotopes. The γ activity induced in targets is measured using a high-resolution HPGe detector. The character of the excitation function changes during the formation of these ions and differs from the excitation functions for deuterons, despite the low bond energy of 3He and the positive values of the Q reactions leading to the formation of 44Sc and 46Sc isotopes. The cross sections of 44Sc formation reach their maximum value at the Coulomb barrier of the reaction, due to the stable 4He nucleus that accompanies the formation of 44Sc. The contribution from different reaction mechanisms to the cross sections of 43Sc, 44Sc, and 46Sc isotope formation are considered.

Cratering response method to study the effect of ultrasonic energy on Cu-wire bonding quality

The paper presents a method for 50μm Cu-wire bonding to study sub-percentage assembly yield loss due to cratering, so called “in-process” cratering. Test vehicle is an audio amplifier device assembled in a surface mount power package (HSOP). The method is based on high temperature aging followed by wire pull testing and has successfully been applied to determine the upper limit of the bond energy process window. After implementation in production, the shift to lower bond energy was controlled via regular ball shear production monitor and “in-process” cratering was no longer observed.

First Principles Study of the Ignition Mechanism for Hypergolic Bipropellants: N,N,N′,N′-Tetramethylethylenediamine (TMEDA) and N,N,N′,N′-Tetramethylmethylenediamine (TMMDA) with Nitric Acid

We report quantum mechanics calculations (B3LYP flavor of density functional theory) to determine the chemical reaction mechanism underlying the hypergolic reaction of pure HNO(3) with N,N,N',N'-tetramethylethylenediamine (TMEDA) and N,N,N',N'-tetramethylmethylenediamine (TMMDA). TMEDA and TMMDA are dimethyl amines linked by two CH(2) groups or one CH(2) group, respectively, but ignite very differently with HNO(3). We explain this dramatic difference in terms of the role that N lone-pair electrons play in activating adjacent chemical bonds. We identify two key atomistic level factors that affect the ignition delay: (1) The exothermicity for formation of the dinitrate salt from TMEDA or TMMDA. With only a single CH(2) group between basic amines, the diprotonation of TMMDA results in much stronger electrostatic repulsion, reducing the heat of dinitrate salt formation by 6.3 kcal/mol. (2) The reaction of NO(2) with TMEDA or TMMDA, which is the step that releases the heat and reactive species required to propagate the reaction. Two factors of TMEDA promote the kinetics by providing routes with low barriers to oxidize the C: (a) formation of a stable intermediate with a C-C double bond and (b) the lower bond energy for breaking the C-C single bond (by 18 kcal/mol comparing to alkane) between two amines. Both factors would decrease the ignition delay for TMEDA versus TMMDA. The same factors also explain the shorter ignition delay of 1,4-dimethylpiperazine (DMPipZ) versus 1,3,5-trimethylhexahydro-1,3,5-triazine (TMTZ). These results indicate that TMEDA and DMPipZ are excellent green replacements for hydrazines as the fuel in bipropellants.

Effect of Selective Condensation on the Characterization of Bio-oil from Pine Sawdust Fast Pyrolysis Using a Fluidized-Bed Reactor

To maximize selective condensation of organics that are of known higher commercial value and to investigate the effects of selective condensation on bio-oil characterization, pine sawdust was pyrolyzed in a 1−5 kg/h bench-scale fluidized-bed reactor. In the experiments, the selective condensers and electrostatic precipitator were used to condense the pyrolysis vapors. In addition, the characterization of bio-oils, gases, and biochar was investigated. The results showed that the total bio-oil, gases, and char yields were 41.5, 43.3, and 15.2%, respectively, and 86.2 wt % water steam was condensed in condenser 1. The bio-oil condensed in the later condensers has a lower water content, higher pH value, higher heating value, and higher kinetic viscosity compared to the first one. Analysis of the 1, 4, and 5 bio-oils with gas chromatography−mass spectrometry (GC−MS) showed that 102 types of chemical compounds were detected and most of the compounds were condensed at different condensers. Therefore, the selective condensation is useful to separate the water and chemical compounds from bio-oil compared to direct contacting condensing. The gas products were mainly CO, H2, CO2, CH4, and C2−C4. Char characteristics were determined by ultimate analysis, Fourier transform infrared (FTIR) spectrometry, and scanning electron microscopy (SEM) methods. A lot of bonds, such as −NH−, −CH−, −C═C−, −CH3, and −C−O−C−, were found in the char samples. It was observed that the surface morphology of the pine particle changed after pyrolysis, and it became thinner and shrank. The thermal decomposition of chemical bonds and the melting of some compounds can break the chemical bonds of the original material, and the chemical bonds with lower bond energies break with priority. The research has provided a useful reference for biomass fast pyrolysis.

Electrochemical sorption of hydrogen in single-wall carbon nanotubes encapsulated in palladium

The distribution of hydrogen in the palladium matrix and single-wall carbon nanotubes (SWCNs) in Pd-SWCN nanocomposite upon electrochemical hydrogenation is quantitatively studied in situ using voltammetry and chronoammetry. The high mobility of hydrogen in nanotubes is discovered and reflected in the low H-SWCN bond energy, which equals 0.073 ± 0.05 eV/H-atom and is close to the hydrogen activation energy (ɛH = 0.072–0.08 eV/H-atom) obtained using vacuum thermal desorption [7]. The presence of SWCN is shown to increase the hydrogen capacity of the Pd-SWCN composite compared to individual palladium by nearly 25%. The hydrogen storage capacity of nanotubes (CH) in Pd-SWCN composite increases with an increase in the Pd-to-SWCN volume ratio (V(Pd)/V(SWCN)). CH reaches the maximum limiting value of 12 wt % at V(Pd)/V(SWCN) > 12.

Influence of oxygen plasma treatment on boron carbon nitride film composition

Variations in the composition and bonds of boron carbon nitride (BCN) film caused due to an oxygen (O2) plasma ashing process are investigated for a low dielectric constant (low-k) insulating film for next generation LSI devices. The O2 plasma treatment is preformed for BCN samples with various C compositions. The etching rate of BCN films with an O2 plasma decreases with increasing C composition. The reaction of O atoms is suppressed in the BCN film with a high C composition. B–N and B–C bonds with lower bond energies are easily broken by the O2 plasma and replaced by the generation of B–O, N–O, and C–O bonds. The B-atom concentration for all samples is decreased significantly by the O2 plasma treatment. Ion bombardment may play a more dominant role than the O-atom reaction in the etching of the BCN film. The existence of C–N bonds with a high bonding energy may suppress etching and incorporation of O atoms.

CHF3 Dual-Frequency Capacitively Coupled Plasma by Optical Emission Spectroscopy

We investigate the intermediate gas phase in the CHF3 13.56 MHz/2 MHz dual-frequency capacitively couple plasma (CCP) for the SiCOH low dielectric constant (low-k) film etching, and the effect of 2 MHz power on radicals concentration. The major dissociation reactions of CHF3 in 13.56MHz CCP are the low dissociation bond energy reactions, which lead to the low F and high CF2 concentrations. The addition of 2 MHz power can raise the probability of high dissociation bond energy reactions and lead to the increase of F concentration while keeping the CF2 concentration almost a constant, which is of advantage to the SiCOH low-k films etching. The radical spatial uniformity is dependent on the power coupling of two sources. The increase of 2 MHz power leads to a poor uniformity, however, the uniformity can be improved by increasing 13.56 MHz power.

Kinetic study of atom transfer radical polymerization of methyl methacrylate in ionic liquids

AbstractThe kinetics of methyl methacrylate (MMA) homopolymerization performed by atom transfer radical polymerization (ATRP) is investigated in detail using ethyl‐2‐bromopropionate (EPN‐Br) as initiator, CuBr as catalyst, and pentamethyldiethylenetriamine (PMDETA) as ligand in ionic liquids (ILs) and acetonitrile. ILs in this research covered two different substitutional imidazolium cations and anions including halogen and halogen‐free ones. The typical cations include 1‐butyl‐3‐methylimidazolium, 1‐ethyl‐3‐methylimidazolium and the typical anions include bromide, tetrafluoroborate. The effects of solvents, temperature, and reaction ingredients ratios on the polymerization kinetics are all investigated in this article and the apparent energy of activation (ΔE) calculated for the ATRP of MMA in 1‐butyl‐3‐methyl‐imidazolium tetrafluoroborate is 6.95 KJ/mol. The number‐average molecular weights (Mn) increase linearly with conversion but are much higher than the theoretical values. It is probably due to the low concentration of deactivator at the early stage of polymerization and the lower bond energy of C‐Br in PMMA‐Br than that in EPN‐Br. Moreover, the catalyst is easily separated from the polymer and the regenerated catalyst is reused for more than three times. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

InSb and InSb:N multiple quantum dots

The authors report the growth and structural properties of InSb and InSb:N quantum dots on InAs and GaAs substrates. Strain induced self-assembled quantum dots are grown using solid-source molecular beam epitaxy. For improved growth control, they developed a growth technique similar to atomic-layer epitaxial methods. InSb and InSb:N multiple quantum dots formed on both InAs and GaAs. They explain the formation of multiple quantum dots by the anisotropic distribution of strain energy within the quantum dot, the long adatom lifetime during atomic-layer epitaxy, and the low bond energy of InSb.

Enhanced photodegradation of bisphenol A in the presence of β‐cyclodextrin under UV light

AbstractEnhancement of the photodegradation of bisphenol A (BPA) by β‐cyclodextrin (β‐CD) was investigated under a 30 W UV disinfection lamp (λmax = 254 nm). The photodegradation rate of BPA in aqueous solutions with β‐CD was faster than that in aqueous solutions without β‐CD; for example, after 50 min of UV irradiation, β‐CD had increased the photodegradation efficiency by about 46.5% for 10 mg dm−3 BPA. The photodegradation of 2.5–20 mg dm−3 BPA in aqueous solutions was found to follow pseudo‐first‐order kinetics. The first‐order rate constant showed a 12‐fold increase in the presence of β‐CD. Factors such as β‐CD concentration, pH, BPA initial concentration and organic solvent influencing the photodegradation of BPA were studied and are described in detail. Variations in the pH and electrical conductivity of solutions were observed during the photodegradation process. The enhancement of photodegradation of BPA results mainly from the lower bond energy between some atoms in the BPA molecule after inclusion interaction with β‐CD. Copyright © 2006 Society of Chemical Industry