Miracle-dz/UniFAR-FTUs huggingface dataset:
Preparation of End-Grafted Polyelectrolyte Brushes on Nanoscale Probe Tips Using an Electric Field

The atomic force microscope (AFM) and related nanomechanical instruments have become fundamental tools for studying molecular, colloidal, and surface forces in physiological fluid environments down to the pN range.1-5 A key component of the AFM is the soft microfabricated cantilever force transducer and fine probe tip (with a typical end radius of RTIP < 50 nm) that deflects when interacting with a sample surface. Standard Si3N4 probe tips have been used for studying the nanomechanical properties of macromolecules on surfaces,1 and probe tips functionalized with proteins, ligands and receptors, cells, and nanotubes have enabled studies of biologically relevant intermolecular interactions.2-5 Probe tip functionalization has been achieved by covalent immobilization, nonspecific physisorption, and conventional adhesives for larger structures (g1 μm). 6-10 However, attachment of macromolecules to the apex of a probe tip with a prespecified orientation, conformation, and density is difficult due to the small surface area involved and, for polyelectrolytes, the presence of fixed charge groups. Functionalization and subsequent characterization of parameters such as the chain grafting density, Γ (chains/nm2), in the vicinity of the tip apex are also difficult and critical to the interpretation of nanomechanical data relating interaction force to tip-sample separation distance. Our recent studies of the biological polyelectrolyte molecules in cartilage,11 chondroitin sulfate glycosaminoglycans (GAGs), called for a new method of attachment and assessment on nanoscale probe tips in order to carry out nanomechanical experiments between two opposing, end-grafted GAG brushes which more closely mimic the physiological conformations found in native tissue. GAGs were chemically end-grafted to an Aucoated Si3N4 probe tip by means of an electric field applied between the probe tip and a nearby Pt electrode. Previously, an electric field was used to attract charged DNA oligonucleotides to a monolayer of single-stranded DNA that had been immobilized on an Au-coated sensor surface through a Au-thiol attachment and a 300 mV potential between the sensor and a Pt electrode was found to enhance hybridization of the DNA oligonucleotides to the DNA monolayer.13 We extended this methodology to use an electric field to drive charged GAG molecules to a nanosized probe tip, thus increasing the local polyelectrolyte concentration in the vicinity of the probe tip and chemisorption via an end-terminal functionality.
Scalar coupling constants across the intramolecular NHN hydrogen bond of symmetrically and non‐symmetrically substituted 6‐aminofulvene‐1‐aldimines

Multinuclear liquid state magnetic resonance experiments have been performed on two seven‐membered 15N‐labeled H‐chelates of the 6‐aminofulvene‐1‐aldimines type in order to characterize the strong intramolecular NHN hydrogen bonds as a function of the molecular symmetry. In particular, the symmetrically substituted N,N′‐diphenyl‐6‐aminopentafulvene‐1‐aldimine‐15N2 (1) and its asymmetric analog N‐phenyl‐N′‐(1,3,4‐triazol)‐ 6‐aminopentafulvene‐1‐aldimine‐15N5 (2) have been studied. For 1, an NN coupling constant across the hydrogen bridge of 2hJ(15N,15N) = 10.6 Hz was determined indirectly by 13C NMR at two different Larmor frequencies, 125.76 and 67.93 MHz; this coupling constant is characteristically enhanced compared with the value of 8.6 Hz obtained previously for 2. Because of a fast degenerate proton tautomerism the hydrogen bond proton in 1 is coupled with both nitrogen atoms with a coupling constant of −40.8 Hz. {15N} tickling experiments were performed on 2 in order to determine the relative signs of the coupling constants of the NHN hydrogen bridge. We find that 2hJ(15N,15N) and 1hJ(1H,15N) = +4.4 Hz exhibit the same sign, i.e. the opposite sign compared with 1J(15N,1H) = −88.6 Hz. This finding proves that 1hJ(1H,15N) corresponds to an intrinsic coupling, which is not induced by a tautomerism absent in 2 because of the large difference in basicities of the aniline and the amino‐1,3,4‐triazole substituents. Therefore, these observations indicate a sign change of J(15N,1H) when the proton is transferred successively from one nitrogen to the other, as observed previously for FHF hydrogen bonds. The relation between the values of the coupling constants and the hydrogen bond geometries is discussed in terms of the valence bond order model, as are the implications for obtaining equilibrium constants of tautomerism from coupling constant data. Copyright © 2001 John Wiley & Sons, Ltd.
IDENTIFICATION OF 11 POLYCYCLIC AROMATIC HYDROCARBONS AND 4-(METHYLNITROSAMINO)-1-(3-PYRIDYL)-1-BUTANONE IN NARGHILE SMOKE

A high-performance liquid chromatography (HPLC) method for the identification of polycyclic aromatic hydrocarbons (PAHs) and 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) in narghile smoke is presented. Combustions of 80 g of “maassel” and 20 cigarettes were first initiated by the use of 3 charcoal disks and secondly by an electrical heater in order to study the role of charcoal in the production of PAH in the smoke. PAHs present in the particle smoke were extracted with toluene. This toluene fraction was passed through a silica cartridge and evaporated. The result was analyzed by HPLC coupled with fluorescence detector. In narghile smoke from charcoal combustion, our results show the presence of seven PAHs: phenanthrene, antracene, fluoranthene, chrysene, benzo(a)pyrene, benzo(b)fluoranthene, and benzo(k)fluoranthene, whereas in the narghile smoke from electrical heater only four of these PAHs were detected: phenanthrene, antracene, fluoranthene, and chrysene. Chloroform extractions of narghile smoke and cigarettes smoke from charcoal combustion were also performed in order to detect the presence of NNK. Chloroform samples were then passed through a cation exchange, and the final extracts were analyzed by HPLC using UV detectors. Although the NNK was present in cigarette smoke, this nitrosamine dropped to below detectable limit in narghile smoke.
Nitric acid oxidation of Si to form ultrathin silicon dioxide layers with a low leakage current density

Ultrathin silicon dioxide (SiO2) layers with excellent electrical characteristics can be formed using the nitric acid oxidation of Si (NAOS) method, i.e., by immersion of Si in nitric acid (HNO3) solutions. The SiO2 layer formed with 61 wt % HNO3 at its boiling temperature of 113 °C has a 1.3 nm thickness with a considerably high density leakage current. When the SiO2 layer is formed in 68 wt % HNO3 (i.e., azeotropic mixture with water), on the other hand, the leakage current density (e.g., 1.5 A/cm2 at the forward gate bias, VG, of 1 V) becomes as low as that of thermally grown SiO2 layers, in spite of the nearly identical SiO2 thickness of 1.4 nm. Due to the relatively low leakage current density of the NAOS oxide layer, capacitance–voltage (C–V) curves can be measured in spite of the ultrathin oxide thickness. However, a hump is present in the C–V curve, indicating the presence of high-density interface states. Fourier transformed infrared absorption measurements show that the atomic density of the SiO.
Notizen: Über Darstellung und Eigenschaften von Calciumaluminiumhydrid Ca(AlH4)2

Calciumaluminiumhydrid wird durch Umsetzung von Aluminiumchlorid und Calciumhydrid in Tetrahydrofuran dargestellt. Das aus der Losung gewonnene Festprodukt enthalt auch in trockenem Zustand noch 40—50% Tetrahydrofuran und ist in seinen Eigenschaften dem Lithiumaluminiumhydrid weitgehend ähnlich.
Temperature-Responsive Clay Aerogel−Polymer Composites

Polymer composites reinforced by hydrophilic clay aerogels were produced and found to possess interpenetrating cocontinuous structures, not the exfoliated structure often observed in clay nanocomposites. An efficient process for producing these clay aerogels was recently reported; in-situ polymerization of N-isopropylacrylamide within the clay aerogels was readily accomplished. The resulting composites have low densities, are stable, and exhibit a new synergistic effect of interpenetrating organic−inorganic phases in which the organic polymer prevents loss of aerogel structure in water by encapsulation, while the inorganic filler increases the structural integrity of the polymer. The composites undergo phase transition and show LCST behavior similar to unmodified poly(N-isopropylacrylamide) despite the presence of reinforcing clay aerogels. Reversible changes in morphology of the aerogel hydrogel composites are observed with varying degrees of hydration.
Fabrication of Nickel–Multiwalled Carbon Nanotube Composite Films with Excellent Thermal Conductivity by an Electrodeposition Technique

Nickel-multiwalled carbon nanotube (MWCNT) composite films were fabricated by an electrodeposition technique, and their microstructure and thermal conductivity were characterized. Nickel-MWCNT composite films with a homogeneous dispersion of MWCNTs throughout the nickel matrix free of any significant voids were electrodeposited from a Ni plating bath containing effective additives and MWCNTs under galvanostatic conditions. The thermal conductivity of the composite films was as high as 109 Wm -1 K -1 , which is about twice that of a nickel film without MWCNTs.
Ordered structure in dilute solutions of highly charged polymer lattices as studied by microscopy. I. Interparticle distance as a function of latex concentration

The coexistence of ordered and disordered regions has been observed in dilute solutions of highly charged monodisperse latex particles, a copolymer of styrene and styrenesulfonate, by using a metallurgical microscope. Unlike latex particles of low charge numbers, the interparticle distances (2Dexp) in the hexagonal ordered regions are smaller than the calculated average values for a face‐centered‐cubic distribution (2D0,h) at low polymer concentrations (0.2–2 vol %). However, at high concentrations, up to 12%, the 2Dexp value approaches 2D0,h. The results are consistent with a ‘‘two‐state structure’’ containing ordered and disordered regions and indicate the existence of ‘‘attractive’’ interactions between the charged solutes. The findings are also consistent with those for other species of high charge densities such as synthetic macroions and simple ions.
FORÇA MUSCULAR DE MEMBROS INFERIORES E POLIMORFISMO DO GENE RECEPTOR DE SEROTONINA COMO FATORES ASSOCIADOS ÀS MULHERES COM FIBROMIALGIA

Introduction: Fibromyalgia (FM) is a rheumatic syndrome characterized by chronic generalized skeletal muscle pain. Its etiology is not well defined, as there are several factors involved in its etiopatology, such as physical and / or emotional stresses, or a genetic susceptibility, involving the serotonergic, dopaminergic and catecholaminergic pathways. Objective: To investigate a possible association between lower limb strength, genetic polymorphism of the serotonin receptor gene HTR2A in women with fibromyalgia. Materials and Methods: In this observational case-control study, 48 women belonging to the FM group (52  12 years) and 100 women in the control group (58  11 years) were evaluated. We collected demographic and anthropometric data and peripheral blood samples for DNA extraction; genotypic analyzes were performed using real-time PCR by the TaqMan® system. The lower limb muscle strength was assessed by the sit and stand test of 30 seconds. The chi-square test was used to identify possible associations between the variables; the independent samples t test to compare the means between the groups; the significance level adopted was 5%. Results: There was an association between the polymorphism of the HTR2A gene and FM, demonstrating that GG genotype was 24,39 times more likely to develop the syndrome (95% CI: 5,15 – 115,47; p = 0.01). Association between FM and the sit-up test was verified, demonstrating that fibromyalgic women have lower limb muscle strength (p = 0.01). The study showed that the white race was 3.84 times more likely to develop FM (p = 0.01). Conclusion: It is concluded that white women with GG genotype or G allele are at greater risk of developing fibromyalgia and that these patients present lower limb muscle strength.
Coordination Modes of a Series of Xylylene-Bridged Bis(1,4,7-triazacyclonon-1-yl) Ligands: Synthesis, Structure, and Properties of Nickel(II) and Copper(II) Complexes

Three bis(1,4,7-triazacyclonon-1-yl) ligands, 1,2-bis(1,4,7-triazacyclonon-1-ylmethyl)benzene (L1), 1,3-bis(1,4,7-triazacyclonon-1-ylmethyl)benzene (L2), and 1,4-bis(1,4,7-triazacyclonon-1-ylmethyl)benzene (L3), have been synthesized and their nickel(II) and copper(II) coordination chemistry investigated. Reaction of L1 with excess Ni2+ ions affords a mixture of mononuclear and binuclear complexes, which are readily separated by cation exchange chromatography and crystallized as their perchlorate salts, [NiL1](ClO4)2 (1) and [Ni2L1(H2O)6](ClO4)4· 4H2O (2). Similar treatment of L2 and L3 with excess Ni2+ ions affords exclusively the binuclear complexes [Ni2L2(H2O)6](ClO4)4 (3) and [Ni2L3(H2O)6](ClO4)4·3H2O (4), respectively. Reaction of all three ligands with excess Cu2+ ions also yields binuclear complexes, which may be isolated as neutral species, [Cu2LBr4]·xDMF (5, L = L1, x = 1; 6, L = L2, x = 0; 7, L = L3, x = 0), or as perchlorate salts, [Cu2L(H2O)4](ClO4)4·xH2O (8, L = L1, x = 5; 9, L = L2, x = 4; 1.
1,7-Dioxaspiro[5.5]undecanes. An excellent system for the study of stereoelectronic effects (anomeric and exo-anomeric effects) in acetals

Several isomeric compounds derived from the spiro systems 5 to 9 (Scheme 4) were obtained from the acid cyclization of the appropriate dihydroxy ketone precursor.The configuration and the conformation of the products obtained was determined by 13C nmr analysis and equilibration studies. The experimental results can be rationalized by taking into account the anomeric and the exo-anomeric effects and the usual steric interactions.
Effect of addition of various salts on coal extraction with carbon disulfide/N-methyl-2-pyrrolidinone mixed solvent

The effect of addition of various salts on the extraction of seven different kinds of coals with carbon disulfide−N-methyl-2-pyrrolidinone (CS2−NMP) mixed solvent (1:1 by volume) was investigated. Lithium and tetrabutylammonium salts with various anions were used as additives for the coal extraction. Addition of some salts considerably increased the extraction yield for several coals. For Upper Freeport coal, in particular, the addition of a very small amount (0.25 mol/kg-coal) of tetrabutylammoniumfluoride increased the extraction yield from 60 to 84%. The results for the halogenide salts indicate that a kind of halogenide anion affects the extraction yields. The yields increased in the order, F- > Cl- > Br- > I-, indicating that the anions with the small ion radius or large electronegativity are effective for the enhancement of the yield. Some qualitative explanations for the observations were made using the Hard and Soft Acids and Bases principle. The role of anions for the enhancement of coal solubili.
Lignin depolymerization (LDP) in alcohol over nickel-based catalysts via a fragmentation–hydrogenolysis process

Valorization of native birch wood lignin into monomeric phenols over nickel-based catalysts has been studied. High chemoselectivity to aromatic products was achieved by using Ni-based catalysts and common alcohols as solvents. The results show that lignin can be selectively cleaved into propylguaiacol and propylsyringol with total selectivity >90% at a lignin conversion of about 50%. Alcohols, such as methanol, ethanol and ethylene glycol, are suitable solvents for lignin conversion. Analyses with MALDI-TOF and NMR show that birch lignin is first fragmented into smaller lignin species consisting of several benzene rings with a molecular weight of m/z ca. 1100 to ca. 1600 via alcoholysis reaction. The second step involves the hydrogenolysis of the fragments into phenols. The presence of gaseous H2 has no effect on lignin conversion, indicating that alcohols provide active hydrogen species, which is further confirmed by isotopic tracing experiments. Catalysts are recycled by magnetic separation and can be reused four times without losing activity. The mechanistic insights from this work could be helpful in understanding native lignin conversion and the formation of monomeric phenolics via reductive depolymerization.
Simulations of Phenol Adsorption onto Activated Carbon and Carbon Black

Grand canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulations have been used to study the adsorption of phenol onto carbon materials. Activated carbon was modelled in terms of its pore-size distribution based on DFT methods, while carbon black was represented by a single carbon slab with varying percentages of surface atoms removed. GCMC results for adsorption from the corresponding gas phase were in reasonable agreement with experimental adsorption results. MD simulations, that studied the influence of the presence of water and surface roughness on the arrangement of the adsorbed phenol molecules, showed that the interaction between the adsorbed molecules was strongly influenced by the presence of water.
Molecular Dynamics Study of Water Structure Confined in Vibrative Silicon Plates

A physical model of the bulk-nanochannel-bulk with buffer bathes has been set up in this paper using molecular dynamics (MD) simulation. The distribution of water molecules and counterions Na+ in the nanochannel region with different surface charge densities is studied when silicon atoms vibrate. Simulation results show that the interaction between the charged surfaces and the ions in the channel results in an enrichment of counterions. With the increase of the surface charge density, the vibration effect of silicon atoms on the distribution of water molecules and Na+ ions cannot be ignored, which results in the decreasing of adsorbed peak and increasing of the first hydration peak. The concentration of Na+ increases and it distributes farther away from the wall. In addition, the ion exchange between nanochannel region and bath boxes is considered, so it is not electrical neutrality in the nanochannel region, and its electrical property depends on the surface charges.
The CSD–450,000 answers … but what are the questions?

A brief survey about the development of knowledge of crystal and molecular structure based on the Cambridge Structural Database (CSD) is given. The CSD may be considered as a database of answers to the question as to which polymorph will form under given crystallization conditions. The emphasis of research over the years has moved from molecular structural geometry, to intermolecular motifs and to wider considerations of crystal packing similarity. Some experimental data items, not recorded in the CSD, place limitations on the usefulness of the CSD, in future research. Unanswered questions are discussed in the areas of crystal structure prediction, polymorphism, co-crystal and solvate formation.
Retrieval of field-level information of sugarcane using unmanned aerial vehicle (UAV) data under different approaches = Aquisição de informações em nível de campo da cana-de-açúcar utilizando dados de um veículo aéreo não tripulado (VANT) sob diferentes metodologias

The application of remote sensing as tool in precision agriculture has become increasingly common due to its ability to provide spatially and temporally distributed information. In this context, low-altitude remote sensing is a relatively new concept for the acquisition of images. Sensors placed on an unmanned aerial vehicle (UAV) can provide data that attend especially to the critical requirements of spatial and temporal resolution for agricultural applications. Therefore, crop production with economic, environmental and energy importance, such as sugarcane, can benefit from the information provided by this technology. Thus, the main objective of this research was exploring the potential and limitations of the use of UAVs in monitoring sugarcane. Through methodological developments to use the UAV data, was extracted qualitative and quantitative data and compared them with field and satellite data to test the study’s hypothesis. The first part of this thesis describes an object-based image analysis (OBIA) procedure for UAV images, designed to map and extract information about skips in sugarcane planting rows. The approach achieved good results with a relationship of estimated versus observed skip length of 97%. The second part describes the generation of crop surface models (CSMs) derived from high-resolution images from the UAV to estimate the height of sugarcane fields. Also, was investigated the influence of different flight lines on the height estimation and the accuracies by comparing the generated maps with ground references. This method was ideal for estimating the average height of an entire field at once, instead of using point-wise ground measurements. In the third part, the UAV data (RGB) and the orbital platform data (multispectral, WorldView-2) were analyzed, to assess the capability of each system to represent the intra-field variability of sugarcane yield estimates. The results showed that the UAV data produced mean errors similarly, but with lower explanatory power compared to the WorldView-2 data. Moreover, the incorporation of both datasets (WorldView-2 + UAV) improved the accuracy. In summary, was concluded that a UAV system can provide useful decision-support data for improving sugarcane production. These platforms have the capability of providing very-high resolution images with near real-time acquisition.
Roles of H2in annealing and growth times of graphene CVD synthesis over copper foil

Single-layer and high-quality graphene was synthesized over Cu foil by atmospheric pressure chemical vapor deposition (CVD) without additionally introducing H2 gas during the growth time. We compared the Cu surface morphology and graphene growth evolution as a function of time, with and without H2 gas supply during the growth time, by AFM, SEM, EBSD, and Raman spectroscopy. The comparison results suggested that the absence of H2 gas supply during the growth time caused the orientated wrinkles, small grain size, more grain boundaries on the Cu surface, as well as high graphene quality and a rapid growth rate. The cross sectional TEM, HR-TEM, and SAED indicated the homogeneity and high quality, which was also confirmed by the low sheet resistance of 710 Ω sq−1. To elucidate the roles of H2 in the annealing and growth times, we introduced H2 at the individual stages of heating, growth, and cooling steps. The data showed that graphene could be grown only when H2 was introduced during the growth time, indicating that the H2 from CH4 pyrolysis was not responsible for graphene growth. Therefore, the existence of H2 during the growth time was essential for graphene growth. This result led us to infer that the H2 introduced during the annealing time could be released from the bulk Cu to promote graphene growth. The release process was further confirmed by the detection of H2 concentrations using a hydrogen analyzer. The results are beneficial to highlight the roles of H2 in the individual reaction steps for the controllable synthesis of graphene.
The structure of small metal clusters

One metal atom surrounded by its 12 nearest neighbors is considered for both D3d (face‐centered cubic‐like) and D3h (hexagonal close‐packed‐like) geometries. For Al and Be, the neutral cluster and the positive and negative ions are considered for idealized (all bonds equal) and distorted geometries. The D3d geometry is found to be the lowest for Be13, while the D3h geometry is lower for Al13. This is the reverse of what is expected based upon the bulk metal structures, Be(hcp) and Al(fcc). Al13 is found to have only small distortions, while Be13 shows large distortions for both the D3d and D3h geometries. The ions have geometries which are similar to those found for the neutral systems. Both all‐electron and effective core potential calculations were carried out on the X13 clusters; the agreement is very good.