Miracle-dz/UniFAR-FTUs huggingface dataset:
Dynamical Study of Guest-Host Orientational Interaction in LiquidCrystalline Materials

Guest-host interaction has long been a subject of interest in many disciplines. Emphasis is often on how a small amount of guest substance could significantly affect the properties of a host material. This thesis describe our work in studying a guest-host effect where dye-doping of liquid crystalline materials greatly enhances the optical Kerr nonlinearity of the material. The dye molecules, upon excitation and via intermolecular interaction, provides an extra torque to reorient the host molecules, leading to the enhanced optical Kerr nonlinearity. We carried out a comprehensive study on the dynamics of the photoexcited dye-doped liquid crystalline medium. Using various experimental techniques, we separately characterized the dynamical responses of the relevant molecular species present in the medium following photo-excitation, and thus were able to follow the transient process in which photo-excitation of the dye molecules exert through guest-host interaction a net torque on the host LC material, leading to the observed enhanced molecular reorientation. We also observed for the first time the enhanced reorientation in a pure liquid crystal system, where the guest population is created through photoexcitation of the host molecules themselves. Experimental results agree quantitatively with the time-dependent theory based on a mean-field model of the guest-host interaction.
A next-generation apparatus for lithium optical lattice experiments

Quantum simulation is emerging as an ambitious and active subfield of atomic physics. This thesis describes progress towards the goal of simulating condensed matter systems, in particular the physics of the Fermi-Hubbard model, using ultracold Lithium atoms in an optical lattice. A major goal of the quantum simulation program is to observe phase transitions of the Hubbard model, into Néel antiferromagnetic phases and d-wave superfluid phases. Phase transitions are generally accompanied by a change in an underlying correlation in a physical system. Such correlations may be most amenable to probing by looking at fluctuations in the system. Experimental techniques for probing density and magnetization fluctuations in a variety of atomic Fermi systems are developed. The suppression of density fluctuations (or atom “shot noise”) in an ideal degenerate Fermi gas is observed by absorption imaging of time-of-flight expanded clouds. Intrap measurements of density and magnetization fluctuations are not easy to probe with absorption imaging, due to their extremely high attenuation. A method to probe these fluctuations based on speckle patterns, caused by fluctuations in the index of refraction for a detuned illumination beam, is developed and applied first to weakly interacting and then to strongly interacting in-trap gases. Fluctuation probes such as these will be a crucial tool in future quantum simulation of condensed matter systems. The quantum simulation experiments that we want to perform require a complex sequence of precisely timed computer controlled events. A distributed GUI-based control system designed with such experiments in mind, The Cicero Word Generator, is described. The system makes use of a client-server separation between a user interface for sequence design and a set of output hardware servers. Output hardware servers are designed to use standard National Instruments output cards, but the client-server nature allows this to be extended to other output hardware. Output sequences running on multiple servers and output cards can be synchronized using a shared clock. By using an FPGA-generated variable frequency clock, redundant buffers can be dramatically shortened, and a time resolution of 100ns achieved over effectively arbitrary sequence lengths.
Synthesis and nanocharacterisation of magnetic nanoparticles : from cubes and spheres to octapods and wires

This thesis details the chemical synthesis and nanocharacterisation of magnetic nanoparticles (MNPs). Throughout this thesis, solution-based synthesis methods are used to fabricate MNPs with a variety of shapes, from spheres and cubes to wires and octapods. Chapter 3 assesses the role of polyol solvent in autoclave-based magnetite NP synthesis. It was found that solvents containing functional groups (especially primary alcohols) afforded the greatest control over final MNP morphology and that the presence of additional alkyl substituents could disrupt the packing of surfactant molecules around a particle surface, giving rise to more complex ‘compound’ MNPs. Magnetic measurements show the particles to be superparamagnetic, with saturation magnetisation values close to that of the bulk. In Chapter 4 It was found that by replacing the polyol solvents used in Chapter 3 with a large excess of bulky surfactant molecules it was possible to form high aspect ratio lanthanide oxide (LnOx) nanowires and ribbons. It was found that the nanowires formed via an intriguing 3-stage ‘oriented assembly’ mechanism, in which individual NPs form, before aligning anisotropically and recrystallising into a more crystallographically homogeneous product. The magnetic properties of Gd2O3 nanowires and Dy2O3 nanoribbons are very similar to those of discrete particles, implying that no long-range ordering exists in the nanowires. Optical characterisation of the Eu2O3 nanowires showed that there is an increase in fluorescence lifetime going from bulk Eu2O3 to the nanoscale. In Chapter 5 the high temperature reflux approach is used in the synthesis of manganese oxide (as MnO) particles, using manganese-containing polynuclear carboxylate complexes as precursors. It was found that control over MnO NP size and shape is dependent on many factors, such as the carboxylate ligand present in the precursor (which can disrupt particle stabilisation by surfactant molecules) and the heating regime, which ii determines if the particles grow under thermodynamic or kinetic growth regimes. The magnetic behaviour of MnO MNPs was found to be dependent on the relative number of surface spins present in the particles. In Chapter 6 new routes to gadolinium-doped magnetite particles are discussed. It was found that decomposition of a single-source precursor yielded doped magnetite particles which had a gadolinium content of 2–4%. Magnetic characterisation of these particles showed them to be superparamagnetic, with a reduced saturation magnetisation compared to bulk magnetite. Preliminary investigations showed that the gadolinium doped particles (after being rendered water soluble by a ligand exchange reaction) were readily taken up by human fibroblast cells and exhibited low toxicities.
Open-air direct current plasma jet : scaling up, uniformity, and cellular control

Atmospheric-pressure plasma jets are commonly used in many fields from medicine to nanotechnology, yet the issue of scaling the discharges up to larger areas without compromising the plasma uniformity remains a major challenge. In this paper, we demonstrate a homogenous cold air plasmaglow with a large cross-section generated by a direct current power supply. There is no risk of glow-to-arc transitions, and the plasmaglow appears uniform regardless of the gap between the nozzle and the surface being processed. Detailed studies show that both the position of the quartz tube and the gas flow rate can be used to control the plasma properties. Further investigation indicates that the residual charges trapped on the inner surface of the quartz tube may be responsible for the generation of the air plasma plume with a large cross-section. The spatially resolved optical emission spectroscopy reveals that the air plasma plume is uniform as it propagates out of the nozzle. The remarkable improvement of the plasma uniformity is used to improve the bio-compatibility of a glass coverslip over a reasonably large area. This improvement is demonstrated by a much more uniform and effective attachment and proliferation of human embryonic kidney 293 (HEK 293) cells on the plasma-treated surface.
Measurement of DMS, DMSO, and DMSP in natural waters by automated sequential chemical analysis

Dimethyl sulfide (DMS), dimethylsulfoniopropionate (DMSP), and dimethyl sulfoxide (DMSO) are key components of the marine sulfur cycle. The concentrations of these compounds exhibit large spatial and temporal variability in the surface ocean, creating a need for high resolution sampling. Existing automated underway measurement systems for DMS do not measure DMSP or DMSO, so their spatial variability is less well‐characterized. We present an accurate and robust method for the automated, high throughput sampling and measurement of DMS, DMSO, and DMSP (DMS/O/P) in a single water sample. The method is based on a three‐step sequence of purge and trap gas chromatography, where DMS analysis is followed by the enzymatic reduction of DMSO to DMS and the alkaline hydrolysis of DMSP to DMS. The system, which we call the Organic Sulfur Sequential Chemical Analysis Robot (OSSCAR), includes automated calibrations and blank determinations. OSSCAR can be used as a front‐end system for any sulfur detector and is suited for continuous underway analysis or the measurement of discrete water samples. The system described here has a minimum detection limit of ∼ 0.1 nM of DMS/O/P in a 2.5 mL sample. Assessment of liquid standards and intercalibration against independent analytical systems demonstrate good precision and accuracy of our method. Shipboard analysis of surface water DMS/O/P concentrations on a transect from Ocean Station Papa (50°N, 145°W) to Vancouver Island demonstrates the utility of OSSCAR for mapping variability in reduced sulfur compounds across dynamic and contrasting oceanographic conditions.
Evaluated Kinetic, Photochemical and Heterogeneous Data for Atmospheric Chemistry: Supplement V. IUPAC Subcommittee on Gas Kinetic Data Evaluation for Atmospheric Chemistry

This paper updates and extends previous critical evaluations of the kinetics and photochemistry of gas-phase chemical reactions of neutral species involved in atmospheric chemistry [J. Phys. Chem. Ref. Data 9, 295 (1980); 11, 327 (1982); 13, 1259 (1984); 18, 881 (1989); 21, 1125 (1992)]. The work has been carried out by the authors under the auspices of the IUPAC Subcommittee on Gas Phase Kinetic Data Evaluation for Atmospheric Chemistry. Data sheets have been prepared for 658 thermal and photochemical reactions, containing summaries of the available experimental data with notes giving details of the experimental procedures. For each reaction, a preferred value of the rate coefficient at 298 K is given together with a temperature dependence where possible. The selection of the preferred value is discussed and estimates of the accuracies of the rate coefficients and temperature coefficients have been made for each reaction. The data sheets are intended to provide the basic physical chemical data needed as .
X-ray photoemission spectra and x-ray excited Auger spectrum investigation of the electronic structure of Pd3(PS4)2

Information on the bonding states of the compositional atoms and on the occupied energy states of the Pd3(PS4)2 crystals have been obtained by investigating the Pd 3d and P and S 2p core levels and the valence band region with the x-ray photoemission spectroscopy. In particular, as far as core levels are concerned, each XPS spectrum, apart from the spin-orbit splitting, exhibits a single-peak structure suggesting the absence of nonequivalent sites for the compositional atoms. The analysis of the chemical shifts in the core-level binding energies of the constituents emphasizes their cation or anion-type behavior. As to the valence band (VB) XPS spectrum, two regions are distinguished and interpreted on the basis of the comparison with the VB XPS spectra of other palladium and (PS4)3− compounds and of some thiophosphates. Confirmation of an involvement of the Pd 4d in the bonding is also given by the analysis of the spectral shape of the x-ray induced Pd M45VV Auger transition.
Nutrients transport through variably structured soils

Soil structure development has a direct and indirect relation with hydraulic properties that generally control the transport of surface applied nutrients in unsaturated zones causing environmental implications. Nitrate ( ) and phosphate ( ) transport was assessed using undisturbed columns of variably structured calcareous soils, i.e. Shahdara (massive to weak coarse sub-angular blocky silt loam), Sultanpur (weak coarse, sub-angular blocky very fine sandy loam), Lyallpur (weak, coarse and medium sub-angular blocky silt loam), and Pacca (moderate, medium and fine sub-angular blocky silty clay). After conditioning the columns with 0.01 M CaCl2 (≈2 pore volumes), a pulse of KNO3 (50 mM) and KH2PO4 (32 mM) solution was applied and afterwards leached with 0.01 M CaCl2. The experimental breakthrough curves (BTCs) of and were described with one-domain and two-domain (mobile–immobile) convective dispersive equations (CDEs). Results showed that both and , applied in the same pulse, appeared in the effluent almost immediately after pulse application and peaked after 0.4 pore volume cumulative drainage in Lyallpur and Pacca columns. In contrast, in the Sultanpur and Shahdara columns, appearance of in the effluent was delayed till 0.6 pore volume and 0.4 pore volume cumulative drainage, respectively, and peaked at ≈1.0 pore volume cumulative drainage. The appearance of in the effluent was further delayed until 0.8 pore volume and 0.6 pore volume cumulative drainage, respectively. The despersivity, λ, that occurred in the Lyallpur and Pacca columns was significantly greater than in Shahdara and Sultanpur columns. While the fitted mobile water fraction, β, was significantly greater in Shahdara (0.81) and Sultanpur (0.90) than that of Lyallpur (0.27) and Pacca (0.28). It was concluded that variable structured soils had significant effect on solute transport parameters and should be considered in nutrient management studies.
Effects of Soil Alkalization on Osmotic Adjustment and Ion Balance in Sorghum (Sorghum Bicolor L.)

Sorghum (Sorghum bicolor L.) was grown on an alkalinized plot for 90 days. Inorganic ions and compatible solutes were measured to investigate the physiological adaptations by which sorghum tolerates natural alkaline stress. Plant growth was clearly inhibited. The stress led to increased Na+ content in roots but had only a small effect on Na+ accumulation in leaves; K+ content in roots was lower than that in leaves and stems; and Na+ content and Na+/K+ ratio were much higher in roots than in leaves and stems. These suggest that maintaining a substantially higher osmotic potential in roots for greater uptake of water and restricting the spread of Na+ to shoots are physiological adaptations to alkalinity. Soluble sugar was the main osmolyte in roots, stems, and leaves; proline, amino acids, and oxalates contributed to osmotic regulation slightly, and it was noteworthy that K+ played a major role in osmotic regulation in leaves.
Novel secondary metabolites from myxobacteria and their biosynthetic machinery

This thesis deals with natural products from myxobacteria. Myxococcus xanthus extracts were screened by LC-MS for novel secondary metabolites. Altogether 4 different substance families were isolated and characterized. Identification and analysis of the associated biosynthetic gene clusters allows interesting insights into diverse biosynthetic routes of myxobacteria. The cittilin gene cluster was identified in the genome of M. xanthus. For the first time, in case of a myxobacterial secondary metabolite, it could be demonstrated by heterologous expression in S. aurantiaca Sga 15 that the cittilin precursor peptide is built by the ribosome. Modification of the genetic code yielded novel cittilin derivates. The novel myxoprincomides (mxp) core structure is produced by a NRPS/PKS hybrid biosynthetic pathway in M. xanthus DK897 and DK1622. 10 mxp derivates from DK897 were isolated and correlated to the so far largest myxobacterial biosynthetic gene exhibiting 39 catalytic domains. The mxp biosynthesis is exciting due to incorporation of unusual amino acids and other rare structural features, particularly in comparison to mxp of DK1622. Strikingly, the number of 10 mxp derivates mainly representing hydrolytically released intermediates of the biosynthesis. Prechondrochloren was isolated from a C. crocatus Cm c5 mutant and structurally elucidated. Furthermore it was shown that a spontaneous mutant of S. cellulosum So ce90 produces novel spirangien derivates with a shortened chromophore. Die vorliegende Arbeit befast sich mit Naturstoffen aus Myxobakterien. Mittels LC-MS wurde in Extrakten von Myxococcus xanthus Kulturen nach neuen Sekundarmetaboliten gesucht. Insgesamt wurden 4 unterschiedliche Substanzfamilien isoliert und charakterisiert. Die Identifizierung der zugrundeliegenden Biosynthesegencluster zeigt interessante Einblicke in unterschiedliche Biosynthesewege von Myxobakterien. Das Cittilingencluster wurde im Genom von M. xanthus Stammen identifiziert. Fur einen myxobakteriellen Sekundarmetaboliten konnte durch heterologe Expression in S. aurantiaca Sga 15 erstmalig bewiesen werden, dass dieser ribosomalen Ursprungs ist. Die Modifikation des genetischen Codes fuhrte zu neuen Cittilinen. Die neuen Myxoprincomide werden durch einen NRPS/PKS-Hybrid Biosyntheseweg gebildet. 10 Myxoprincomidderivate wurden aus M. xanthus DK897 isoliert. Mit 39 katalytischen Domanen ist es das bislang groste myxobakterielle Biosynthesegen. Aufgrund ungewohnlicher Aminosauren sowie seltener Strukturmerkmale, ergibt sich insbesondere im Vergleich zu M. xanthus DK1622 fur die Myxoprincomide eine ausergewohnliche Biosynthese. Erstaunlich ist auch die Vielzahl von 10 Derivaten, die grostenteils als Intermediate der Biosynthese hydrolytisch freigesetzt werden. Des Weiteren wurden Prechondrochloren von einer C. crocatus Cm c5 Mutante sowie neue Spirangiene mit einem verkurzten Chromophor von einer zufalligen S. cellulosum So ce90 Mutante isoliert und strukturell aufgeklart.
Optimización de la producción y calidad en cebolla cabezona (Allium cepa) mediante el balance nutricional con magnesio y micronutrientes (B, Zn y Mn), Valle Alto del Río Chicamocha, Boyacá*

La ausencia de magnesio y micronutrientes (B, Zn y Mn) en planes de fertilizacion limita el balance nutricional en cebolla, debido a que dichos elementos regulan la expresion del potencial productivo del cultivo y la calidad del producto cosechado. La presente investigacion fue realizada en un suelo del Distrito de Riego del Alto Chicamocha (DRAC), clasificado taxonomicamente como Sulfic Endoaquept, familia muy fina sobre organica, caolinitica, semiactiva, isomesica (fase acida, moderadamente profunda). Los resultados mostraron respuestas favorables a la fertilizacion complementaria especifica con 70 kg·ha - 1 de MgO (micromagnesio granulado 40% MgO), donde se reportaron incrementos de 50 % en el rendimiento de primera, mejora en la gravedad especifica con diferencias altamente significativas respecto al solo manejo NPK, y se identifico una mayor eficiencia en la absorcion foliar del P estableciendose una relacion positiva Mg/P. Respecto al comportamiento de micronutrientes se presento una interaccion positiva Mn·Zn con 4 kg·ha -1 Mn (microman-sulfato de manganeso granulado, 20% Mn) y 3,5 kg·ha -1 Zn (microzinc-sulfato de zinc granulado 22% Zn), expresada por incrementos superiores al 18% (P
Phosphorus fertilizer form affects phosphorus loss to waterways: a paired catchment study

Two catchments were used to test the hypothesis that using reactive phosphate rock (RPR), a low water soluble fertilizer, instead of superphosphate, could decrease phosphorus (P) export in streams. The sheep‐grazed catchments, each ca. 12 ha in size, received 20–25 kg P/ha either as RPR or superphosphate for 3 yr. Filterable (<0.45 μm) reactive P (FRP) and total P (TP) in stream samples were then compared against two subsequent years when both catchments received 20 kg P/ha as superphosphate. On average, during the 5‐yr study, loads of FRP and TP in stream flow were low (110 g FRP/ha and 358 g TP/ha), typical of dry sheep‐grazed hill country. However, FRP (58%) and TP (38%) in stream flow were significantly less when RPR was applied instead of superphosphate. Where appropriate climatic and soil conditions exist to maintain agronomic targets, RPR could be used to decrease P export in streams.
The Effect of solvents on C-S-H as determined by thermal analysis

Un-hydrated Portland cement consists of several anhydrous and reactive phases, that when mixed with water react to form hydrates. The main hydration product of Portland cement is calcium silicate hydrate (C-S-H). It is the main binding phase in a concrete system, hence is important to construction chemists. The concrete engineer measures the compressive strength of concrete after prescribed hydration periods, typically 1, 3, 7, 28 days. It is often convenient to mimic these intervals by stopping the hydration reaction at the same times. Several techniques can be employed to stop this hydration reaction. One of which is solvent-based and involves mixing a polar solvent such as acetone or isopropyl alcohol, with the hydrated cement. This mixing should be vigorous enough to blend the free water, in the partially hydrated cement system, with the polar solvent without altering the cement system’s matrix. The solvent-water mixture has a much lower boiling point and the mixture quickly evaporates out of the system. This achieves two goals. It stops the hydration reaction at the moment of solvent mixing, and it removes free water to prevent further hydration from occurring. This procedure theoretically leaves behind a dry, chemically unaltered, partially hydrated cement paste. In this way, pastes can be analyzed after the prescribed 1, 3,7, or 28 days of hydration. This paper uses thermogravimetric analysis (TG) results to investigate the assumption that solvents have no thermodynamic or chemical effect on the hydrated cement paste phases.
Beyond homogenization: the formation of very small emulsion droplets during the processing of milk by a Microfluidizer

Comparisons were made of the particles of fat and casein produced when milk is treated with a Microfluidizer, or is homogenized by a valve homogenizer. The results show that the particles in the two milks are very different, especially if several passes through the apparatus are used. The milks treated by Microfluidizer contain smaller particles overall than the homogenized milks, but these particles also have different structures. Specifically, the membranes of protein around the fat globules are different, and in the microfluidized milks, there are fewer intact or semi-intact micelles forming the surface of the fat globule. Also, the microfluidized milk contains very small particles of fat (30-50 nm in diameter), coated with protein. These small particles can exist on their own, but often also were found to be inserted into apparently intact casein micelles. The significance of these results for the understanding of homogenized milks is discussed, with some suggestion of the mechanism of formation of the different types of particle.
Solvothermal synthesis of oriented hydroxyapatite nanorod/nanosheet arrays using creatine phosphate as phosphorus source

Synthesis of hydroxyapatite (HAp) oriented arrays is difficult but significant in biomineralization research for biomaterials. Herein, a novel strategy for the synthesis of HAp nanorod/nanosheet oriented arrays has been developed in the presence of biomolecules of creatine phosphate (CP) using solvothermal treatment in mixed solvents of N,N-dimethylformamide (DMF) and water. In this reaction system, CP biomolecules act as an organic phosphorus source and a soft template for the formation of HAp oriented arrays. This method does not need any hard template or surfactant, avoiding the procedures and cost for their removal from the product. The products are characterized with X-ray powder diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy and thermogravimetric analysis. The formation mechanism of HAp nanorod/nanosheet oriented arrays is discussed.