Miracle-dz/UniFAR-FTUs huggingface dataset:
The influence of conformational fluctuations on enzymatic activity: modelling the functional motion of β-secretase

Considerable insight into the functional activity of proteins and enzymes can be obtained by studying the low energy conformational distortions that the biopolymer can sustain. We carry out the characterization of these large scale structural changes for a protein of considerable pharmaceutical interest, the human β-secretase. Starting from the crystallographic structure of the protein, we use the recently introduced β-Gaussian model to identify, with negligible computational expenditure, the most significant distortions occurring in thermal equilibrium and the associated timescales. The application of this strategy helps us to gain considerable insight into the putative functional movements and, furthermore, allows us to identify a handful of key regions in the protein which have an important mechanical influence on the enzymatic activity despite being spatially distant from the active site. The results obtained within the Gaussian model are validated through an extensive comparison against an all-atom molecular dynamics simulation.
Demonstration of aluminium in polyphosphate of Laccaria amethystea (Bolt. ex Hooker) Murr. by means of electron energy‐loss spectroscopy

Toxic aluminium species in acidified soil damage the rootlets of trees. The symbiotic association with ectomycorrhizal fungi may, however, protect the rootlets by sequestration of aluminium in polyphosphates. Electron energy‐loss imaging and spectroscopy was used to identify the relative amount of aluminium in the polyphosphate of the mycelium of the ectomycorrhizal fungus Laccaria amethystea. A three‐window method at the L2,3 edge yielded results which were in agreement with the spectra obtained at the aluminium K edge. The aluminium net distribution images were recorded at 85 eV, the backgrounds at 70 eV and 60 eV, setting the energy selecting slit to 5 eV and the beam current to 15 μA. The method can be used to study the sequestration of aluminium in mycelia of ectomycorrhizal fungi under different stress situations.
A New Mechanism for Chemically Induced Dynamic Nuclear Polarization in the Solid State

Electron−electron−nuclear three-spin mixing is discussed as a source of a new type of CIDNP effects that is peculiar to the solid state. The build-up of nonequilibrium nuclear spin polarization by this mechanism does not require singlet−triplet branching with different fates of the radicals in the two branches. Rather it is a polarization transfer from the electron−electron zero-quantum transition to the nuclear spins in the vicinity of a 2-fold avoided level crossing. An analytical expression is derived that describes this transfer for short times after the radical generation. Under this condition, the size of the effect is proportional to the static field, to the electron−electron spin coupling, and to the square of the anisotropy of the hyperfine coupling. An estimate of the order of magnitude of the resulting polarization reveals that three-spin mixing could be the source of recently observed solid-state CIDNP effects in bacterial photosynthetic reaction centers. CIDNP effects of this type should occu.
Van der Waals energy of a 1-dimensional lattice

Van der Waals dispersion forces are examined for an infinite one-dimensional (1D) chain of atoms. Building on the work of Bade and Kirkwood (J. Chem. Phys. 27, 1284, 1957), dipolar fluctuations of the 1D chain are analyzed in terms of polarization waves. The van der Waals energy of the chain is evaluated from the zero-point energy of these waves. Several results are found. (1) A critical value exists for the dimensionless coupling parameter ν = α0/a 3, for large polarizabilities (α0) or small lattice spacings (a). When ν > 0.208, the 1D line has divergences in both the dispersion relation of the waves and the effective site polarizability. The resulting instability is analogous to 1D ferroelectricity. (2) The sum of higher order (than three-body) interactions are shown to be more important than three-body interactions (which are small); when ν approaches 0.208, the higher order terms are comparable to the two-body term. (3) Finite 1D chains of N atoms behave like infinite chains when N exceeds 100. (4) 1D surface tensions deviate from two-body predictions for large values of the coupling parameter (ν > 0.10).
Desulfurization of Diesel Fuel by Extraction with Lewis-Acidic Ionic Liquid

Abstract Ionic liquids were found to be highly selective for the extractive removal of aromatic sulfur compounds from fuels at room temperature. The efficiency of ionic liquids for the removal of aromatic sulfur compounds is dependent on the properties and structure of the ionic liquids. In this work, the Lewis-acidic ionic liquid 1-butyl-3-methylimidazolium tetrahalogenoferrate(III) ([BMIM] [FeCl4]) was synthesized and demonstrated to be more effective for the removal of aromatic sulfur compounds from diesel over ionic liquids 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) and 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM] [BF4]) because of its Lewis-acidic property. The ionic liquids favorably extracted organic compounds with a higher density of aromatic π-electrons. [BMIM][FeCl4] ionic liquid can be regenerated through reextraction by hexane, and could be used in multiple steps for the removal of sulfur compounds from diesel.
Modeling the Fate of Expiratory Aerosols and the Associated Infection Risk in an Aircraft Cabin Environment

The transport and deposition of polydispersed expiratory aerosols in an aircraft cabin were simulated using a Lagrangian-based model validated by experiments conducted in an aircraft cabin mockup. Infection risk by inhalation was estimated using the aerosol dispersion data and a model was developed to estimate the risk of infection by contact. The environmental control system (ECS) in a cabin creates air circulation mainly in the lateral direction, making lateral dispersions of aerosols much faster than longitudinal dispersions. Aerosols with initial sizes under 28 μm in diameter can stay airborne for comparatively long periods and are favorable for airborne transport. Using influenza data as an example, the estimated risk of infection by inhalation are at least two orders of magnitude higher than the risk of infection by contact. An increase in the supply airflow rate enhances ventilation removal and the dispersion of these aerosols. It reduces the risk of infection by inhalation for passengers seated within one row and one column from the index patient but it increases the risk for passengers seated further away. The deposition fraction increases with aerosol size. The ECS supply airflow rate has insignificant impact on the deposition behavior of these large aerosols, making the impact on the risk of infection by contact insignificant. Comparatively, the contact behavior of passengers is highly influential to the contact infection risk. Passengers seated within one row from the index patient are subject to contact risks that are one to two orders of magnitude higher than are passengers seated further away.
Co-crystallization of solvents with polymers: The x-ray diffraction behavior of solvent-containing and solvent-free polyacrylonitrile

Differences in the x-ray diffraction pattern of polyacrylonitrile (PAN) have been observed, both here, as well as in the work reported in the literature. Various workers have cited grossly differing unit cells for PAN and this has never been explained. In this work, it is shown that in dry samples, the diffraction pattern contains only two equatorial peaks, d1 ≈ 5.3 A and d2 ≈ 3.0 A. This is consistent with a hexagonal packing of rod-like chains of PAN with no chain-axis order. However, in solvent-plasticized films, the diffraction pattern is altered. It is proposed that certain solvents cause a hexagonal to orthohombic transition. However, the orthorhombic polymorph appears to be a solvated form, where the solvent has co-crystallized with the polymer. After removal of solvent, the structure reverts to hexagonal packing. Hence, it is suggested that the discrepancy in cell parameters cited in the literature, particularly when large cell dimensions are quoted, may be due to the inadvertent presence of solvent which could have been introduced during sample preparation. Similarities with solvated crystls in other polymeric systems are also briefly discussed. © 1994 John Wiley & Sons, Inc.
Preparation of K2La2Ti3O10 by polymerized complex method and photocatalytic decomposition of water

A polymerized complex (PC) technique was applied to the preparation of a highly active photocatalyst, K2La2Ti3O10, with a layered perovskite type structure to decompose H2O into H2 and O2. The catalyst prepared by the PC technique had a higher photocatalytic activity than that prepared by conventional solid-state reaction method.
Dynamics of electron-hole pair recombination in semiconductor clusters

The kinetics of radiative electron-hole pair recombination in CdS and Cd{sub 3}As{sub 2} clusters (where the radius of the cluster is smaller than the de Broglie wavelength of photogenerated excitons) were studied with picosecond photon counting luminescence decay measurements over wide temperature and energy ranges. The decay profiles were quantitatively examined with several models. The decays are composed of two distinct time regimes, each with very different temperature and emission energy dependence. The first (fast) regime is attributed to an unusually efficient thermal repopulation mechanism. The second (slow) component is well described by a distributed kinetic model. The kinetic behavior of wide (CdS) and narrow (Cd{sub 3}As{sub 2}) band gap materials was remarkably similar when composed of clusters in the quantum confined regime.
On-surface coordination chemistry of planar molecular spin systems: novel magnetochemical effects induced by axial ligands

Paramagnetic transition-metal complexes assembled on surfaces are of great interest for potential applications in organic spintronics. The magnetochemical interactions of the spin of the metal centers with both ferromagnetic surfaces and optional axial ligands are yet to be understood. We use a combination of X-ray magnetic circular dichroism (XMCD) and quantum-chemical simulations based on density functional theory (DFT + U) to investigate these metal–organic interfaces with chemically tunable magnetization. The interplay between an optional axial ligand (NO, spin S = 1/2 or NH3, S = 0) and Ni and Co ferromagnetic surfaces affecting the spin of Co(II) tetraphenylporphyrin (d7, S = 1/2), Fe(II) tetraphenylporphyrin (d6, S = 1), Mn(II) tetraphenylporphyrin (d5, S = 5/2) and Mn(II) phthalocyanine (d5, S = 3/2) is studied. We find that the structural trans effect on the surface rules the molecular spin state, as well as the sign and strength of the exchange interaction with the substrate. We refer to this observation as the surface spin-trans effect.
CALCULATION OF REACTIVITY SCALES USING AN UPDATED CARBON BOND IV MECHANISM

This report describes a calculation of the Maximum Incremental Reactivity (MIR) and the Maximum Ozone Incremental Reactivity (MOIR) scales using an updated version of the Carbon Bond IV chemical mechanism which is being used in the air quality modeling in Phase II of the Auto/Oil Air Quality Improvement Research Program. Except for the mechanism, the methodology and model scenarios employed are essentially the same as used to calculate the MIR and MOIR scales used in the California Air Resources Board "Clean Fuels/Low Emissions Vehicle" regulations.
Calculation of low‐energy elastic cross sections for electron‐CF4 scattering

A new computational approach has been used to evaluate the rotationally summed, vibronically elastic integral cross sections from the scattering of slow electrons (energy ranging from 1.0 eV up to 40.0 eV) by tetrafluoromethane molecules in the gas phase. The various symmetry components have been analyzed using the exact static exchange approximation and also by including a nonempirical, model polarization potential employed before by our group. A comparison with earlier calculations and with existing experiments allows us to assign the symmetries of the shape resonances in the 5–30 eV energy region which are seen by experiments and are also shown by the present calculations.
An Improved Deprotection Procedure of Amine-Containing Oligonucleotides from Acrylonitrile Modification

Abstract Alkylation of alkylamine by acrylonitrile via Michael addition1 occurred when standard ammonium hydroxide deprotection was used. The alkylation was greatly reduced using an improved two-step procedure when BCE phosphotriester protecting groups were selectively removed with t-butylamine prior to ammonium hydroxide deprotection.
Water‐in‐oil Emulsions Stabilized by Hydrophobized Microfibrillated Cellulose

The properties of water‐in‐toluene emulsions stabilized solely by hydrophobized microfibrillated cellulose (MFC) were investigated. By varying the degree of surface substitution (DSS), the wettability of the MFC was altered. All emulsions prepared with MFC displayed excellent stability to coalescence. The stability to gravity‐induced sedimentation increased with increasing MFC concentration, the highest stability being obtained with MFC of moderate hydrophobicity. Drop sizes increased with increasing DSS, with a corresponding decrease in stability to sedimentation. An increase in the toluene:water ratio at constant MFC concentration resulted in a decrease in the average drop size. For all emulsions, the polydispersity in drop size decreased with decreasing average drop diameter.
Thermodynamics of High Polymer Solutions

A statistical mechanical treatment of high polymer solutions has been carried out on the basis of an idealized model, originally proposed by Meyer, which is analogous to the one ordinarily assumed in the derivation of the ``ideal'' solution laws for molecules of equal size. There is obtained for the entropy of mixing of n solvent and N linear polymer molecules (originally disoriented), ΔS=−k[(n/β) ln v1+N ln v2] where v1 and v2 are volume fractions and β is the number of solvent molecules replaceable by a freely orienting segment of the polymer chain. This expression is similar in form to the classical expression for equal‐sized molecules, mole fractions having been replaced by volume fractions. When the disparity between the sizes of the two components is great, this expression gives entropies differing widely from the classical values, which accounts for the large deviations of high polymer solutions from ``ideal'' behavior. The entropy of disorientation of a perfectly arranged linear polymer is found t.
Flexible Piezoresistive Sensor Patch Enabling Ultralow Power Cuffless Blood Pressure Measurement

Noninvasive and real‐time cuffless blood pressure (BP) measurement realizes the idea of unobtrusive and continuous BP monitoring which is essential for diagnosis and prevention of cardiovascular diseases associated with hypertension. In this paper, a wearable sensor patch system that integrates flexible piezoresistive sensor (FPS) and epidermal electrocardiogram (ECG) sensors for cuffless BP measurement is presented. By developing parametric models on the FPS sensing mechanism and optimizing operational conditions, a highly stable epidermal pulse monitoring method is established and beat‐to‐beat BP measurement from the ECG and epidermal pulse signals is demonstrated. In particular, this study highlights the compromise between sensor sensitivity and signal stability. As compared with the current optical‐based cuffless BP measurement devices, the sensing patch requires much lower power consumption (3 nW) and is capable of detecting subtle physiological signal variations, e.g., pre and postexercises, thus providing a promising solution for low‐power, real‐time, and home‐based BP monitoring.
Relationship between the hydrodynamic radius and the radius of gyration of a polymer in solution

Recent advances in quasi-elastic laser light scattering techniques have permitted measurements of diffusion coefficients of polymer solutions with a considerable degree of accuracy. From these results, the hydrodynamic radius RH can be obtained from the Stokes-Einstein equation. It is our aim in this note to review the relation between RG and the radius of gyration, RG, calculated according to the Fox-Flory equation. In this wellknown relationship’):
Secondary Ion Mass Spectrometry

Secondary ion mass spectrometry (SIMS) is a technique for surface and thin-film analysis with a long history and a mature instrumental base dating from the early 1960s, which nevertheless has only recently achieved broad credibility as an analytical technique. This lack of acceptance stems from the complexity ofthe sputtering and ion emission processes, which are still imperfectly understood. Impact of a heavy ion (oxygen or heavier) on a surface at energies of a few ke V results in the ejection (sputtering) of surface material, with typical yields of one to several atoms per incident ion. A fraction of this sputtered flux is ionized during the ejection process; this fraction is an extremely sensitive function of the chemistry of the surface and of the sputtered species. Atoms, clusters of atoms, and intact molecular species can all be ejected and ionized, with varying efficiencies. Mass spectrometric analysis of the sputtered (secondary) ion flux allows chemical identification of the sputtered species. All elements can be detected, including hydrogen and helium, and recent developments in sampling methods have made the technique increasingly important in molecular mass spectrometry. SIMS has been extensively reviewed in recent years, from a variety of viewpoints. Various reviews emphasized instrumental aspects (1), analytical applications (2, 3), comparison with other surface analytical techniques (4--9), applications to surface studies (10, 1 1), and fundamental aspects of ion emission (12, 13). A series of biennial international conferences, beginning in 1977, has charted the development of the field (14--16); the proceedings of the most recent in this series (16) offers a useful snapshot of the field at the present time.
Molecular dynamics prediction of phonon-mediated thermal conductivity of f.c.c. Cu

The phonon-mediated thermal conductivity of f.c. c. Cu is investigated in detail in the temperature range 40–1300 K. The calculations are performed in the framework of equilibrium molecular dynamics making use of the Green–Kubo formalism and one of the most reliable embedded-atom method potentials for Cu. It is found that the temporal decay of the heat current autocorrelation function (HCACF) of the Cu model at low and intermediate temperatures demonstrate a more complex behaviour than the two-stage decay observed previously for the f.c. c. Ar model. After the first stage of decay, it demonstrates a peak in the temperature range 40–800 K. A decomposition model of the HCACF is introduced. In the framework of that model we demonstrate that a classical description of the phonon thermal transport in the Cu model can be used down to around one quarter of the Debye temperature (about 90 K). Also, we find that above 300 K the thermal conductivity of the Cu model varies with temperature more rapidly than , following an exponent close to −1.4 in agreement with previous calculations on the Ar model. Phonon thermal conductivity of Cu is found to be about one order of magnitude higher than Ar. The phonon contribution to the total thermal conductivity of Cu can be estimated to be about 0.5% at 1300 K and about 10% at 90 K.
Clarke's Analytical Forensic Toxicology

1. Introduction to Forensic Toxicology 2. Pharmacokinetics and Metabolism 3. Drugs of Abuse 4. Other Poisons 5. Workplace Drug Testing 6. Alternative Specimens 7. Postmortem Toxicology 8. Clinical Toxicology 9. Drug Abuse in Sport 10. Drug-Facilitated Sexual Assault 11. Alcohol, Drugs and Driving 12. Forensic Chemistry & Solid Dosage Form Identification 13. Sampling, Storage and Stability 14. Extraction 15. Colour Tests and Thin-Layer Chromatography 16. Immunoassays 17. Ultraviolet, Visible and Fluorescence Spectrophotometry 18. Infrared Spectroscopy 19. Gas Chromatography 20. High-Performance Liquid Chromatography 21. Mass Spectrometry 22. Quality Control and Assessment
Photocatalytic H2 Evolution on MoS2/CdS Catalysts under Visible Light Irradiation

Photocatalytic H2 production on MoS2/CdS photocatalysts in the presence of different sacrificial reagents under visible light (λ > 420 nm) has been investigated. The transformation process of the Mo species loaded on CdS, together with the junctions formed between MoS2 and CdS, was clearly demonstrated with X-ray photoelectron spectroscopy and transmission electron microscopy. Photocatalytic H2 evolution was optimized for MoS2/CdS catalysts. The 0.2 wt % MoS2/CdS catalyst calcined at 573 K achieves the highest overall activity for H2 evolution, and the 0.2 wt % MoS2/CdS catalyst demonstrates even higher activity than the 0.2 wt % Pt/CdS, irrespective of different sacrificial reagents used. The junctions formed between MoS2 and CdS play an important role in enhancing the photocatalytic activity of MoS2/CdS catalysts. Electrochemical measurements indicate that MoS2 is an excellent H2 evolution catalyst, which is another very important factor responsible for the enhancement of the photocatalytic activity of .
Radial $B-V/V-K$ color gradients, extinction-free $Q_{BVK}$ combined color indices, and the history of star formation of the Cartwheel ring galaxy

In this paper we model and analyse the B V=V K radial color gradients observed in the Cartwheel ring galaxy. Along with the color-color diagrams, we use the QBV K combined color indices, which minimise the uncertainties in the observed B V and V K colors introduced by dust extinction. To model the optical and near-infrared color properties of the Cartwheel galaxy, we assume that an intruder galaxy generates an expanding ring density wave in the Cartwheel's disk, which in its turn triggers massive star formation along the wave's perimeter according to the Schmidt law. We use the population synthesis to calculate the color properties of stellar populations formed in the expanding density wave. The results of color modelling suggest that the pre- collision Cartwheel was a late-type spiral, embedded in an extensive gaseous disk of sub-critical surface density. The properties of the old stellar disk are typical for the late-type Freeman disks, with the central surface brightness in V-band and the scale length being 0 =2 1:0 mag arcsec 2 and R0 = 2 kpc respectively. The pre-collision gaseous disk has a metallicity gradient ranging from z = z=3:5 at the outer regions to z = z in the central regions. At present, the wave of star formation has passed the initial extent of the pre-collision, old stellar disk and is currently moving in the predominantly gaseous, low-metallicity disk at the radius of 16 kpc. Neither young stellar populations formed in an expanding density wave, nor their mixture with the old, pre-collision stellar populations can reproduce the B V and V K colors of the Cartwheel's nucleus+inner ring. We nd that an additional 10-Myr-old burst of star formation in the nuclear regions, along with the visual extinction of AV =1 : m 3, might be responsible for the peculiar colors of the Cartwheel's nucleus.