Miracle-dz/UniFAR-FTUs huggingface dataset:
Synthesis of LCC Model Compounds and Their Chemical and Enzymatic Stabilities

Hydrolysis with dioxane-water (1:1) at 180 °C for one hour allows to break the phenylglycosidic linkage but remains undegraded at least 85% of the glycosidic bond at 7-hydroxyl of lignin side chain. Boron tribromide treatment of all model compounds results in a nearly quantitative Splitting of sugar components. The glycosidic bond between carbohydrate and lignin component is hydrolyzed completely by heating with 1N-H2SO4 at 100 °C for 6 hours, but sugar-lignin bond of ether type locating at 7-position of lignin side chain does not undergo acid hydrolysis. Sodium hydroxide (5%) treatment at ambient temperature never cleavage all of the glycosidic bonds synthesized here except compound III, but benzyl ether type locating at -position of phenylpropane unit is unstable even for very dilute alkali. It was found that methyl ether of this type compound, Villa also suffered alkaline degradation even at near ambient.temperature if the prolonged reaction time was employed. Cellulase preparations (Cellulosin AC and AP) hydrolyze quantitatively all of the glycosidic linkages of lignin-carbohydrate synthesized here even though the aglycon is so bulky äs dimer of phenylpropane unit. Enzymatic hydrolysis rate is larger in alkylated phenolic hydroxyl in comparison to free phenolic hydroxyl, in the former, benzylated one being more faster than the ethylated. Phenylxyloside is subjected to enzymatic hydrolysis more easily compared with phenylgiucoside.
Ultrafast electron dynamics and the role of screening

This thesis focuses on the ultrafast dynamics of electronic excitations in solids and how they are influenced by the screening of the Coulomb interaction between charged particles. The impact of screening on electron dynamics is manifold, ranging from modifications of electron-electron scattering rates over trapping of excess charges to massive renormalisation of electronic band structures. The timescales of these dynamical processes are directly accessible by femtosecond time-resolved photoemission and optical spectroscopy. Three exemplary systems are investigated to shed light onto these fundamental processes: Vanadiumdioxide undergoes a phase transition from a monoclinic insulator to a rutile metal. Apart from temperature, doping and other influences, the insulatorto-metal transition can also be driven by photoexcitation. This, in the past, gave rise to a controversy about the timescales of structural and electronic transition and raised the question which of them constitutes the driving mechanism. Using timeresolved photoelectron spectroscopy, it is shown that the electronic band gap of the insulator collapses instantaneously with photoexcitation and without any structural involvement. The reason is a change of screening due to the generation of photoholes. At the same time, the symmetry of the lattice potential changes, as seen by coherent phonon spectroscopy. This potential change is likely to initiate the structural phase transition from monoclinic to rutile structure. However, the initial non-equilibrium situation can be described by a metallic electronic structure with the atoms still in the monoclinic lattice positions. The SrTiO3/vacuum interface exhibits a two-dimensional electron gas (2DEG), which is delocalised within the surface plane, but localised perpendicular to it. The lower dimensionality changes the form of the screened Coulomb interaction and the phase space within the 2DEG, leading to modified hot carrier lifetimes. These are investigated by time-resolved photoemission spectroscopy: The predicted 2D behaviour is confirmed and two distinct final states within the unoccupied electronic band structure are discovered. Furthermore, the population of the 2DEG is transiently increased by photoexcitation from localised in-gap states into the 2DEG. A different type of screening by dipole moments in amorphous ice layers, is exploited to stabilise and trap electrons within the polar medium in front of a metal surface. Thereby, the mean free path of low energy electrons in amorphous ice is estimated. Moreover, the trapped electrons are used to drive a chemical reaction: A persistent modification of the surface electronic structure of the ice layer is explained via the ‘dielectron hydrogen evolution reaction’. Understanding the role of screening in these systems allows to explain seemingly unrelated effects, like trapping of excess electrons in ice and the insulator-to-metal transition in VO2, within the same concept.
Polymeric nanoparticles for therapy and imaging

Polymeric nanoparticles and their applications have been studied over the long period. Polymeric nanoparticles have been shown to be promising carriers for drug delivery because of their potential in encapsulating drugs hence protecting them from excretion and metabolism. Different polymers have been used, and different strategies such as surface modification have been carried out to increase the retention time of nanoparticles and to increase therapeutic benefit while minimizing side effects. Here, we review aspects of polymeric nanoparticles and their application in magnetic resonance imaging technology, disease therapy, drug delivery systems, and gene transfer. Copyright © 2014 John Wiley & Sons, Ltd.
Synchrotron infrared spectroscopy of OH-chondrodite and OH-clinohumite at high pressure

Abstract High-pressure synchrotron infrared (IR) absorption spectra were collected at ambient temperature for OH-chondrodite and OH-clinohumite up to 38 and 29 GPa, respectively, using argon as the pressure- transmitting medium. The crystal structures of both clinohumite and chondrodite are preserved up to the maximum pressure. However, disordering of the silicate framework appears to become more pronounced at high pressure based on significant broadening of the IR bands with increasing pressure. All three OH bands in both structures shift linearly to higher frequency with pressure up to 18 GPa. Above 18 GPa, the variation of OH frequency with pressure remains linear; however, the slopes for the three OH bands are significantly different as a result of different degrees of hydrogen bonding. The IR results are compared to those from recent Raman studies in which water was used as the pressuretransmitting medium.
Force Field for Mica-Type Silicates and Dynamics of Octadecylammonium Chains Grafted to Montmorillonite

Layered silicates are widely used in nanotechnology and composite materials. We describe a force field for phyllosilicates (mica, montmorillonite, and pyrophyllite) on the basis of physically justified atomic charges, van der Waals parameters, vibrational constants, and distributions of charge defects in agreement with solid state 29Si NMR data. Unit cell parameters deviate only ∼0.5% relative to experimental X-ray measurements and surface (respectively cleavage) energies deviate less than 10% from experimental data, including the partition between Coulomb and van der Waals contributions. Reproduction of surface energies facilitates quantitative simulations of hybrid interfaces with water, organics, and biomolecules for which accurate force fields are available. Parameters are consistent with the force fields PCFF (polymer consistent force field), CVFF (consistent valence force field), CHARMM (chemistry at Harvard macromolecular mechanics), and GROMACS (Groningen machine for chemical simulations). As an e.
Baeyer-Villiger Monooxygenases from a Dietzia sp. - Enzyme Discovery, Characterization and Engineering

With the emergence of Green Chemistry, biocatalysis is becoming an important approach in many laboratory and industrial processes. Enzymes catalyse chemical reactions with high regio- and stereoselectivity at mild conditions and, most importantly, are able to form products that are not possible to obtain by conventional synthetic chemistry. Monooxygenases are a fascinating group of enzymes which oxidise substrates using atmospheric oxygen and release water as a by-product. These enzymes have great potential applications and indeed there are already some industrial showcases. Monooxygenases are of different types and one of the important groups is known as Baeyer-Villiger monooxygenases (BVMOs). BVMOs oxidise ketones to esters and heteroatoms to the corresponding oxide, which are intersting reactions for pharmaceutical and fine chemical industry. To date, several BVMOs have been discovered and characterised; however, there are many limitations, such as poor stability which hindered the wide application of these enzymes. Thus, the search for better BVMOs has continued. This thesis reports the discovery of four BVMOs from the genome sequence of Dietzia sp. D5, a microorganism rich in oxygenases. The genes were cloned and expressed, and two of them were characterised. One of the enzymes, named BVMO3 readily oxidises linear aliphatic ketones. Characterization of the other BVMO, called BVMO4, revealed that it is the second most stable native BVMO ever reported and it oxidises a wide range of substrates. The oxidation of sulfides and aldehydes has been investigated further. Aldehydes were oxidised by this BVMO with a rare regioselectivity, producing carboxylic acid rather than formate ester which is the commonly observed product. Site saturation mutagenesis of selected amino acid residues in the proximity of the active site increased the cyclohexanone oxidation efficiency of BVMO4 by twelve-fold.
The Performance Characteristics of Anaerobic Baffled Reactor (ABR) Fermentation System

A anaerobic baffled reactor (ABR) with an effective volume of 28.7 L was adopted, and the hydrogen production efficiency was investigated with diluted molasses as the substrate. Using a mixture of aerobic and anaerobic activated sludge, the ABR was start-up with a hydraulic retention time (HRT) of 24 h and 35°C. When the influent chemical oxygen demand (COD) concentration was gradually increased from 500 mg/L to 6000 mg/L after a 63-day operation, the ABR kept a steady state. The increase of influent COD concentration, from 6000 mg/L to 8000 mg/L stage by stage, had the remarkable changes on the fermentative system. The ethanol-type fermentation was formed in the first three compartments, while butyric acid-type fermentation in the 4th compartment. In the steady stage at the influent COD of 8000 mg/L, the biogas (H2) yield was found 61.54 L/d (12.85 L/d) while specific H2 production rate of the activated sludge was 48 L/kgMLVSS∙d. Although the ABR system accumulated hydrogen-producing acetogen, due to the hydrogen-consuming bacteria (methanogen and homoacetogenic bacteria), the hydrogen production efficiency was badly inhibited.
Hydration of alkali-activated slag: thermodynamic modelling

The composition of solid and liquid phases of alkali-activated slag systems was investigated by thermodynamic modelling. The calculations predict the formation of C(–A)–S–H, stratlingite and hydrotalcite in different alkali-activated slag systems, which agrees well with experimental findings. In addition traces of FeS and ettringite are predicted to precipitate. The type of alkaline activator (Na-silicate, NaOH) has no influence on the type of hydrates formed but influences the Ca/Si ratio of the C–S–H. The addition of sodium silicate leads to the formation of C–S–H with a higher Ca/Si ratio (1.1–1.2), whereas NaOH results in a Ca/Si ratio of 0.8to1.1. In contrast, the kind and concentration of the activator has strong influence on the composition of the pore solution. Low concentrations of the alkaline activator result in lower Na, Si and Al concentrations and lower pH values. In all pore solutions a high concentration of sulphide (HS–) is expected to be present.
An unexpected softening from WB3 to WB4

We report a drastic reduction of hardness of about 61% from WB3 to WB4. The three-dimensional covalent network consisting of boron honeycomb planes interconnected with strong zigzag W-B bonds underlies the high hardness of WB3. Despite the strong intralayer and interstitial B-B bonds, the interlayer B-B nonbonding and the considerably weak zigzag W-B bonding allow the layers of WB4 to cleave readily, which results in the anomalous softening of WB4. The results provide robust evidence that the highest boride of tungsten, which is characterized experimentally by an inexpensive superhard material, should be stoichiometric WB3, not WB4.
Isolation and Synthesis of Two New 3-Arylcoumarin Derivatives from the Root of Glycyrrhiza Glabra (Licorice), and Structure Revision of an Antioxidant Isoflavonoid Glabrene

Abstract Two new 3-arylcoumarin derivatives were isolated from the root of Glycyrrhiza glabra (licorice; Fabaceae), and their structures were elucidated as 2′,4′-dihydroxy-[6″,6″-dimethylpyrano(2″,3″:7,8)]-3-arylcoumarin and [6′,6″-dimethylpyrano(2″,3″:7,8)]-2′-hydroxy-4′-methoxy-3-arylcoumarin on the basis of spectroscopic evidence. Chemical syntheses of these two pyrano-3-arylcoumarins are described. Two other known isoflavonoids glabrene and glabrone were also obtained, and the structure of the former is revised based on 13C-NMR analysis and NOE experiments.
Cyano- and nitro-containing compounds from the roots of Semiaquilegia adoxoides

Four cyano-containing compounds, (1E,4α,5β,6α)4,5,6-trihydroxy-2-cyclohexen-1-ylideneacetonitrile (1), lithospermoside (2), 4-hydroxy-2-β-D-glucopyranosyl oxyphenylacetonitrile (3) and 4-[β-Dhapiofuranosyl-(1→6)-O-β-D-glucopyranosyl oxy]phenylacetonitrile (4), and a nitro-containing one, 4-[β-D-xylopyranosyl-(1→6)-O-β-D-glucopyranosyloxy]-1-(2-nitroethyl)benzene (5), as well as eleven other types of compounds, were isolated from the roots of Semiaquilegia adoxoides. Their structures were elucidated mainly by spectroscopic methods. Among them, 1 and 4 are new isolated compounds. The cyano- and niawcontaining compounds are very rare in plants and their isolation from one traditional Chinese medicine is really interesting.
Crystal structure of (6E)-2-[(ortho-hydroxy)benzylidene]-1-[4,5-dihydro- 5-(ortho-hydroxy-phenyl)-1,3,4-thiadiazo-2-yl-4-isoproylidenonium]- hydrazine chloride, C18H19ClN4O2S

Abstract C18H19ClN4O2S, monoclinic, I2/a (no. 15), a = 15.771(4) Å, b = 11.101(3) Å, c = 22.072(6) Å, β = 101.986(9)°, V = 3780.0 Å3, Z = 8, Rgt(F) = 0.0551, wRref(F2) = 0.1538, T = 200 K.
Investigation of Carbohydrate Metabolism and Transport in Castor Bean Seedlings by CyclicJCross Polarization Imaging and Spectroscopy

NMR experiments using13C-labeled compounds offer the possibility of noninvasive monitoring of carbohydrate transport and metabolism in living plants, but are usually hampered by the low sensitivity of the13C nucleus. The problem of low sensitivity can be overcome by using the cyclicJcross polarization (CYCLCROP) technique, which allows the indirect detection of13C nuclei coupled to1H nuclei with the high NMR sensitivity of protons. We report here on methods for imaging and spectroscopy based on the CYCLCROP technique, and their use in the firstin vivoNMR study of carbohydrate transport and metabolism in castor bean seedlings (Ricinus communis L.). Comprehensive acquisition strategies for the various NMR methods are given, including the procedure for setting up the experiments. In addition, a full analysis of the effect of relaxation on the signals generated from smallJ-coupled spin systems by the CYCLCROP sequence is given, and the high sensitivity of the sequence is demonstrated. In thein vivostudy of six-day-old castor bean seedlings, we were able to measure the uptake of labeled hexoses, supplied in solution to the cotyledons, and their conversion to sucrose, as well as the transport of this sucrose in the vascular bundles. Images of the actual distribution of labeled sucrose in the hypocotyl of the seedling have also been obtained. The resulting data show some evidence for a preferential incorporation of labeled fructose in the process of sucrose synthesis, which decreases with the time of incubation.
The Specific Heat of Graphite from 13° to 300°K

The specific heat of high‐purity Acheson graphite prepared by the National Carbon Company has been measured from 13° to 300°K. In the region 13° to 54°K the Cp data follows a T2 dependence quite accurately in agreement with previous experimental work and recent theoretical investigations of specific heat in strongly anisotropic solids.On the basis of some recent studies for other highly anisotropic solids, it is suggested that the specific heat of graphite will eventually follow a T3 dependence at still lower temperatures.The derived thermodynamic functions, entropy, enthalpy, and free energy, have been determined by graphical integration and tabulated at integral values of temperature up to 300°K. The entropy of graphite at 298.16°K is 1.372±0.005 cal/g‐atom deg, of which 0.004 is extrapolated from 13° to 0°K assuming the third law and the T2 dependence.
Modern 2D QSAR for drug discovery

2D QSAR is a powerful tool for explaining the relationships between chemical structure and experimental observations. Key elements of the method are the numerical descriptors used to translate a chemical structure into mathematical variables, the quality of the observed data and the statistical methods used to derive the relationships between the observations and the descriptors. There are some caveats to what is essentially a simple procedure: overfitting of the data, domain applicability to new structures and making good error estimates for each prediction. 2D QSAR models are used routinely during the process of optimization of a chemical series towards a candidate for clinical trials. As more knowledge is gained in this area, 2D QSARs will become acceptable surrogates for experimental observations. WIREs Comput Mol Sci 2014, 4:505–522. doi: 10.1002/wcms.1187
CHARACTERIZATION OF C-H-O HYDROGEN-BONDS ON THE BASIS OF THE CHARGE-DENSITY

It is shown that the total charge density is a valid source to confirm hydrogen bonding without invoking a reference charge density. A set of criteria are proposed based on the theory of “atoms in molecules” to establish hydrogen bonding, even for multiple interactions involving C-H-O hydrogen bonds. These criteria are applied to several van der Waals complexes. Finally a bifurcated intramolecular C-H-O hydrogen bond is predicted in the anti-AIDS drug AZT, which may highlight a crucial feature of the biological activity of a whole class of anti-AIDS drugs. Almost all the methods of physical chemistry, spectroscopy, and diffraction can be used to recognize and study hydrogen bonding. ] Each technique focuses on specific properties in order to detect and characterize this phenomenon in its own way. This work is concerned with the manifestation of hydrogen bonding in the charge density obtained from ab initio calculations. Whereas crystallographers have concluded upon hydrogen bonding via purely geometrical criteria, recent deformation density2 studies allow one to observe hydrogen bonding beyond mere ge~metry. ~ However, it is not necessary to subtract an arbitrary (promolecular) charge density from the total density to reveal hydrogen bonding, not even in the interpretation of X-ray experiment^. ^ Boyd and Choi have shown in two important contribution^^^^ that the theory of “atoms in molecules’’ (AIM)7,8 can be used to characterize hydrogen bonding solely from the (total) charge density for a large set of acceptor molecules, involving HF and HC1 as donors. In a next stage Carroll and Bader performed a more extended analysis on a large set of BASE-HF comple~es. ~ This theory has not only provided new insights in conventional intermolecular hydrogenI0. ’ ] bonding but has also been successful in intramolecularI33l4 and x-type hydrogen bonds.I5 Drawing from earlier ob~ervations~~~~ ~. ’~~~~ and the present work, we formulate eight concerted effects occurring in the charge density which are indicative of hydrogen bonding. All of these effects can be viewed as necessary criteria to conclude that hydrogen bonding is present. By observation one of these conditions has proven to be sufficient as well. This case study on C-H-O interactions shows that this less common type of hydrogen bonding obeys all of the proposed criteria. Moreover, the multiple interactions appearing in the present five examples do not impair the consistency of the global phenomenon of hydrogen bonding as it expresses itself in the charge density. In spite of an early affirmative infrared review,I6 the old controversy on whether C-H-O hydrogen bonds really exist continued for another decade,” but now the dust has settled’* (for an entertaining account of this controversy, see ref 19). The importance of these bonds has been recognized in crystal engineering’9,20 since C-H-O contacts have a determining influence on packing motifs.21
Recent Advances on DNA Biosensors

Abstract DNA biosensors are realised immobilising a DNA structure on a suitable transducer to obtain selective information. In this paper we show how the determination of low-molecular weight compounds with affinity for DNA was measured by their effect on the oxidation signal of the guanine peak of calf thymus DNA immobilised on the electrode sensor and investigated by chronopotentiometric analysis. The DNA biosensor is able to detect known intercalating and groove binding compounds. Applicability to river water samples was demostrated. Moreover, a piezoelectric sensor coupled to a short oligonucleotide can be used as detector of the hybridisation reaction. We show as a model the detection of a specific mutation in apolipoprotein E (ApoE) gene. Biotinylated 23-mer probes were immobilised on the streptavidin coated gold surface of a quartz crystal; the protein was covalently bound to the thiol/dextran modified gold surface. The device was able to distinguish different synthetic oligonucleotides. The hybridisation reaction was also performed using real samples of DNA extracted from human blood and amplified by Polymerase chain reaction PCR. The extension of such procedure to samples of environmental interest is discussed.
Polypyrrole-assisted synthesis of roselike MoS2/nitrogen-containing carbon/graphene hybrids and their robust lithium storage performances

Roselike MoS2/nitrogen-containing carbon/graphene (MoS2/NC/G) hybrids were successfully synthesized via a facile polypyrrole (PPy)-assisted hydrothermal approach in combination with high-temperature calcination. The obtained MoS2/NC/G hybrids manifest roselike MoS2 composed of nanosheets coupled uniformly on NC/G nanosheets due to the strong interactions between MoS2 and the abundant nitrogen-containing functional groups of NC. When used as anode materials for lithium ion batteries, the MoS2/NC/G hybrids exhibit enhanced electrochemical energy storage performances compared to the bare MoS2 nanosheets, including high specific capacity (1570.6 mA h g−1 at 0.1 A g−1), excellent rate capability (704.8 mA h g−1 at 5 A g−1) and good cycling stability (96.4% capacity retention after 100 cycles at 0.2 A g−1). The enhanced lithium storage properties of the MoS2/NC/G hybrids can be ascribed to the boosted electronic conductivity arising from the novel hybrid nanostructures of MoS2/NC/G.
Preparation by Hydrothermal Techniques in a Tungstosilicate Acid Solution System and Optical Properties of Tellurium Nanotubes

Single-crystalline tellurium nanotubes can be easily synthesised by a simple hydrothermal, economical and green chemical route. The tungstosilicate acid (TSA) serves as not only an effective reducing agent but also a new morphology-directing agent for tellurium nanotubes from sodium tellurate (Na2TeO3) precursor powders. Scanning electron microscopy images show that most of the tellurium nanotubes have sloping cross-sections and open ends with outer diameters of 100–500 nm, wall thicknesses of 30–100 nm and lengths of 30–50 μm. A few Te nanotubes have hexagonal cross-sections. Te nanotubes grow along the [001] direction and have excellent crystallinity. The synthetic conditions also investigated for the tellurium nanotubes were molar ratio of sodium tellurate to TSA, pH of reaction solution and reaction temperature. The optical properties of the t-Te nanotubes have been investigated. A possible mechanism for the growth of tellurium nanotubes has been discussed. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)