Scattering Measurements Research Articles

Preparation from a revisited wet chemical route of phase-pure, monocrystalline and SHG-efficient BiFeO3 nanoparticles for harmonic bio-imaging

We present two new synthetic routes for bismuth ferrite harmonic nanoparticles (BiFeO3 HNPs). Both phase-pure and mixed phase BiFeO3 materials were produced after improvement of the solvent evaporation and sol-gel combustion routes. Metal nitrates with a series of dicarboxylic acids (tartronic, tartaric and mucic) were used to promote crystallization. We found that the longer the carbon backbone with a hydroxyl group attached to each carbon, the lower the annealing temperature. We also demonstrate that nanocrystals more readily formed at a given temperature by adding glycerol but to the detriment of phase purity, whereas addition of NaCl in excess with mucic acid promotes the formation of phase-pure, monocrystalline nanoparticles. This effect was possibly associated with a better dispersion of the primary amorphous precursors and formation of intermediate complexes. The nanoparticles have been characterized by XRD, TEM, ζ-potential, photon correlation spectroscopy, two-photon microscopy and Hyper-Rayleigh Scattering measurements. The improved crystallization leads to BiFeO3 HNPs without defect-induced luminescence and with a very high averaged second harmonic efficiency (220 pm/V), almost triple the efficiency previously reported. This development of simple, scalable synthesis routes which yield phase-pure and, crucially, monocrystalline BiFeO3 HNPs demonstrates a significant advance in engineering the properties of nanocrystals for bio-imaging and diagnostics applications.

Activation Energy of Organic Cation Rotation in CH3NH3PbI3 and CD3NH3PbI3: Quasi-Elastic Neutron Scattering Measurements and First-Principles Analysis Including Nuclear Quantum Effects.

The motion of CH3NH3+ cations in the low-temperature phase of the promising photovoltaic material methylammonium lead triiodide (CH3NH3PbI3) is investigated experimentally as well as theoretically, with a particular focus on the activation energy. Inelastic and quasi-elastic neutron scattering measurements reveal an activation energy of ∼48 meV. Through a combination of experiments and first-principles calculations, we attribute this activation energy to the relative rotation of CH3 against an NH3 group that stays bound to the inorganic cage. The inclusion of nuclear quantum effects through path integral molecular dynamics gives an activation energy of ∼42 meV, in good agreement with the neutron scattering experiments. For deuterated samples (CD3NH3PbI3), both theory and experiment observe a higher activation energy for the rotation of CD3 against NH3, which results from the smaller nuclear quantum effects in CD3. The rotation of the NH3 group, which is bound to the inorganic cage via strong hydrogen bonding, is unlikely to occur at low temperatures due to its high energy barrier of ∼120 meV.

1.5 GPa compact double-wall clamp cell for SANS and NSE studies at low temperatures and high magnetic fields

We have developed and realised a compact high-pressure clamp cell of the piston-cylinder type for Small Angle Neutron Scattering (SANS) and Neutron Spin Echo (NSE) spectroscopy measurements. The cell can pressurise φ5 mm samples up to 1.5 GPa. It is non-magnetic, produces a sufficiently low and flat SANS background with a relatively good neutron transmission and can be used in combination with polarised neutrons. The cell accommodates samples of up to 55 mm3 in volume and adopts a two-layer geometry: a TiZr body (outer layer) and a CuBe2 insert (inner layer). Its design is very compact and can be employed inside cryomagnets featuring a sample bore greater than φ30 mm. We present the cell and illustrate its performances with a series of neutron scattering experiments performed on single-crystalline MnSi.

Influence of carboxymethylcellulose (NaCMC) on the aggregation and micellization behaviors in aqueous cethylpyridinium chloride solutions: Thermodynamic study and effect of polymer concentration

In the present work, we applied Dynamic Light Scattering (DLS), conductivity and rheological measurements in order to assess the most important characteristics of the interaction between sodium carboxymethylcellulose (NaCMC) and cethylpyridinium chloride (CPCl). We evaluate the effect of temperature and weight-percentage concentration of added NaCMC on critical aggregation (cac) and CPCl-critical micellization concentrations (cmc*) for mixtures NaCMC/CPCl in aqueous solutions. Careful energetic analyses showed that micellization of CPCl in water is entropically driven and exothermic in presence of NaCMC, while for NaCMC/CPCl aggregation, enthalpic and entropic terms are both important. The process of forming micelle-decorated NaCMC skeletons at the cac is more favored by heating and less favored when we add more quantities of NaCMC at fixed temperature. DLS measurements allowed us to imagine a possible scenario of the aggregates shape-size evolution upon adding CPCl. We think that aggregates or “clusters” constructed by several micelle-decorated polymers linked by hydrophobic interaction are responsible of the hydrodynamic radius bump situated at the cac. These entities reach several hundreds of nm and are mainly monodisperse. Moreover, viscosity results showed that these aggregates interconnect by hydrophobic zones that form upon adding more CPCl which leads to a kind of network and probably explains the viscosity bump appearing just after that of hydrodynamic radius. We draw attention however to the role of shearing in the formation of this structure.

Effect of 500 keV Ar2+ ion irradiation on structural and magnetic properties of TiO2 thin films annealed at 900 °C

Present study investigates the structural and magnetic properties of TiO2 thin films prepared by electron beam evaporation technique, annealed at 900 °C and irradiated with 500 keV Ar2+ ions. The films before irradiation exhibit anatase phase. Irradiation leads to diffused XRD peaks indicating amorphisation of the anatase phase at the fluence of 1 × 1014 ions/cm2. Increasing the fluence to 5 × 1016 ions/cm2 leads to evolution of brookite phase out of the amorphous TiO2. In addition, an impurity phase, Ti4O7 is observed in pristine as well as in irradiated films, which show radiation resistant behavior to 500 keV Ar2+ ion irradiation upto the highest fluence 5 × 1016 ions/cm2. Anatase to brookite phase transformation followed by an intermediate amorphous phase occurs without showing either grain growth or change in film thickness as evidenced from Atomic Force Microscopy (AFM) and Rutherford’s Back Scattering (RBS) measurements, respectively. Further, both pristine and irradiated films exhibit ferromagnetic behavior at room temperature (RT) irrespective of their phase and crystallinity. The difference in magnetization observed in pristine and film irradiated at ion fluence 5 × 1016 ions/cm2 is ascribed to the difference in oxygen vacancies.

Interaction of Cu+2 with α-Crystallin: A Biophysical and Mass Spectrometric Study.

αA- and αB- crystallin are members of small heat shock protein family with chaperone property. Their interactions with Cu2+ ions are reported in neurodegenerative diseases. We have been studying the effect of small ionic molecules on the stability of α-crystallin. Cu2+ is co-ordinated with αB-crystallin involving three histidine residues and one aspartic acid residue as potential binding sites. However, copper binding sites for the oligomeric native protein αA-crystallin protein is not known. The objective of this study was to study oligomerization and stability of αA- and αBcrystallin in presence and absence of Cu2+ ions and to find binding sites of Cu2+ on αA-crystallin. The recombinant Human αA- and αB-crystallin proteins were purified after overexpression from the E. coli BL21DE3 cell lysate by a combination of ion-exchange and gel filtration chromatography. Mass analysis of αA- and αB-crystallin in absence and presence of Cu2+ were carried out by MALDI TOF MS. Stability of αA-crystallin in presence and absence of Cu2+ was determined by equilibrium urea denaturation experiments. The equilibrium urea unfolding profiles of the αA-crystallin in absence and presence of different Cu2+ concentrations were fitted according to the three state model of protein unfolding. Dynamic Light Scattering (DLS) measurements were carried out to detect the oligomeric size of αA-crystallin in presence and absence of Cu2+ during urea unfolding. Histidine residues were modified by DEPC (Diethyl pyro carbonate). Chemically modified and unmodified αA-crystallin was digested by trypsin prior to MALDI MS analysis. Cu2+ pre-incubation was done before the chemical modification. Mass spectrometric detection of intact protein allows direct measurement of Cu2+ ions bound to the protein. Thus the average numbers of Cu2+ bound to αA- and αB-crystallin were 4.2 and 3.6 respectively per subunit. It is seen that in presence of Cu2+ ions the free energy (ΔG) of unfolding of αA-crystallin almost doubled. The size analysis by dynamic light scattering data clearly indicated that in presence of Cu2+ ions the oligomeric size remain unchanged with increasing urea solutions. Mass spectrometric detection with chemical modification of histidine residues of αA-crystallin in presence and absence of Cu2+ indicated that amino acid residues H107, H100, H115 of αA-crystallin are involved in Cu2+ binding. Our results indicated that Cu2+ helped in increasing stability of αA-crystallin and three histidine residues H100, H107 and H115 of αA-crystallin are Cu2+ binding residues.

Spectroscopic Characterization of a Lead–Lead Dioxide Automobile Battery

ABSTRACTHere we combine small angle neutron scattering measurements (SANS) with X-ray diffraction analysis (XRD) and infrared spectroscopy (IR) measurements to obtain information about nanoparticles formed in a series of lead-lead dioxide samples mixed with various CuO concentrations. New vitreous systems with the xCuO • (100−x)[4PbO2 • Pb] composition where x = 0, 30, and 70 mol% CuO were prepared by the melt-quenching method using CuO mixed in suitable proportion with the active electrodes of a disassembled car battery as the starting materials. The X-ray diffraction patterns permit the identification of the metallic Pb phase and the presence of oxidic nanoparticles of the lead and copper ions. By doping with higher CuO contents, the SANS curves have a concave shape indicating inhomogeneities and tendency of phase separation due to formation of nanoparticles of the lead and copper ions in recycled host matrix. The studied samples can be considered as polydispersed systems. The matrix is the solvent and the soluble phase is formed from the oxidic lead and/or copper particles with sizes smaller than 69 Å dispersed either inside the host matrix grains or between the host matrix grains. The formation of the nanoparticles in the host matrix and the knowledge of the type of nanoparticles have a decisive role in applications for the construction of essential components of the automobile batteries.

Antimicrobial Activity of New Materials Based on Lavender and Basil Essential Oils and Hydroxyapatite

This study presents, for the first-time, the results of a study on the hydrodynamic diameter of essential oils (EOs) of basil and lavender in water, and solutions of EOs of basil (B) and lavender (L) and hydroxyapatite (HAp). The possible influence of basil and lavender EOs on the size of hydroxyapatite nanoparticles was analyzed by Scanning Electron Microscopy (SEM). We also investigated the in vitro antimicrobial activity of plant EOs and plant EOs hydroxyapatite respectively, against Gram-positive bacteria (methicillin-resistant Staphylococcus aureus1144 (MRSA 1144) and S. aureus 1426) and Gram-negative bacteria (Escherichia coli ATCC 25922 and Escherichia coli ESBL 4493). From the autocorrelation function, obtained by Dynamic Light Scattering (DLS) measurements it was observed that basil yielded one peak at an average hydrodynamic diameter of 354.16 nm, while lavender yielded one peak at an average hydrodynamic diameter of 259.76 nm. In the case of HAp nanoparticles coated with basil (HApB) and lavender (HApL) essential oil, the aggregation was minimal. We found that the lavender EO exhibited a very good inhibitory growth activity (MIC values ranging from <0.1% for E. coli reference strain to 0.78% for S. aureus strains). The biological studies indicated that HapL material displayed an enhanced antimicrobial activity, indicating the potential use of HAp as vehicle for low concentrations of lavender EO with antibacterial properties. Flow cytometry analysis (FCM) allowed us to determine some of the potential mechanisms of the antimicrobial activities of EOs, suggesting that lavender EO was active against E. coli by interfering with membrane potential, the membrane depolarization effect being increased by incorporation of the EOs into the microporous structure of HAp. These findings could contribute to the development of new antimicrobial agents that are urgently needed for combating the antibiotic resistance phenomena.

Fabrication of hollow core–shell conductive nanoparticles based on nanocrystalline cellulose for conductive adhesive

A novel environmentally friendly method was developed to fabricate hollow core–shell conductive nanoparticles using a natural and nontoxic material, nanocrystalline cellulose (NCC), as the template. The NCC used in this study has nano-scale rod-like structure. After the oxidization to dialdehyde cellulose, the insulated NCC was functionalized by poly(dopamine) (PDA) in weakly alkaline conditions through Schiff base reaction and self-polymerization. The Schiff base can be hydrolyzed in an aqueous acetone solution via ultraviolet radiation so that the hollow structure constructed. This structure not only strengthened the mechanical properties but also provided more active sites for silver deposition. Utilizing the chelating ability of the catechol groups in PDA, electroless plating method was used to form the silver coating layer. Scanning electron microscope and Dynamic Light Scattering measurements indicated that these nanoparticles (NPs) had well-defined morphology and a mean diameter of 100–120 nm. Moreover, these prepared Ag–DA–NCC0 NPs exhibited excellent conductivity. Their electrical resistivity reached 0.2 mΩ·cm, which is much higher than that of many other conductive particles used in conductive adhesive.

Tube Expansion Deformation Enables In Situ Synchrotron X-ray Scattering Measurements during Extensional Flow-Induced Crystallization of Poly l-Lactide Near the Glass Transition.

Coronary Heart Disease (CHD) is one of the leading causes of death worldwide, claiming over seven million lives each year. Permanent metal stents, the current standard of care for CHD, inhibit arterial vasomotion and induce serious complications such as late stent thrombosis. Bioresorbable vascular scaffolds (BVSs) made from poly l-lactide (PLLA) overcome these complications by supporting the occluded artery for 3–6 months and then being completely resorbed in 2–3 years, leaving behind a healthy artery. The BVS that recently received clinical approval is, however, relatively thick (~150 µm, approximately twice as thick as metal stents ~80 µm). Thinner scaffolds would facilitate implantation and enable treatment of smaller arteries. The key to a thinner scaffold is careful control of the PLLA microstructure during processing to confer greater strength in a thinner profile. However, the rapid time scales of processing (~1 s) defy prediction due to a lack of structural information. Here, we present a custom-designed instrument that connects the strain-field imposed on PLLA during processing to in situ development of microstructure observed using synchrotron X-ray scattering. The connection between deformation, structure and strength enables processing–structure–property relationships to guide the design of thinner yet stronger BVSs.

Time-Resolving Study of Stress-Induced Transformations of Isotactic Polypropylene through Wide Angle X-ray Scattering Measurements.

The development of a highly oriented fiber morphology by effect of tensile deformation of stereodefective isotactic polypropylene (iPP) samples, starting from the unoriented γ form, is studied by following the transformation in real time during stretching through wide angle X-ray scattering (WAXS) measurements. In the stretching process, after yielding, the initial γ form transforms into the mesomorphic form of iPP through mechanical melting and re-crystallization. The analysis of the scattering invariant measured in the WAXS region highlights that the size of the mesomorphic domains included in the well oriented fiber morphology obtained at high deformations increases through a process which involves the coalescence of the small fragments formed by effect of tensile stress during lamellar destruction with the domain of higher dimensions.

Eco-friendly synthesis of silver nanoparticles using &lt;i&gt;Lactobacillus delbrueckii&lt;/i&gt; subsp. &lt;i&gt;bulgaricus&lt;/i&gt; isolated from kindrimo (locally fermented milk) in Kano State, Nigeria

Silver nanoparticles have gained global popularity because of its application in crucial areas such as medical diagnosis/therapy, solar cell development, water treatment, surface coating and cosmetic production. Bacterial synthesis of silver nanoparticles is regarded as eco-friendly due to minimal waste generated while being energy efficient. This study was aimed at synthesizing silver nanoparticles using Lactobacillus specie isolated from Kindrimo under the influence of sunlight irradiation. Lactobacillus delbrueckii subsp. bulgaricus isolated from Kindrimo was identified using morphological and biochemical techniques and confirmed using 16S rRNA gene sequencing. The eco-friendly protocol for the extracellular synthesis of silver nanoparticles was accomplished by treatment of Lactobacillus delbrueckii subsp. bulgaricus extract with silver nitrate solution in the ratio 1:10 under the influence of sunlight irradiation. Synthesized silver nanoparticles were confirmed and characterized using UV-Visible Spectrophotometry, Dynamic Light Scattering, Transmission Electron Microscopy and Energy Dispersion Spectroscopy. The absorbance spectrum preliminarily confirmed the formation of silver nanoparticles by revealing characteristic broad peak at 415nm. Dynamic Light Scattering measurements further confirmed synthesis by showing average particle size distribution of 147nm. Micrograph of Transmission Electron Microscopy revealed that the synthesized silver nanoparticles were polyhedral and spherical in shape with size ranging 1.4 to 8.9nm. The elemental composition of the resultant colloidal solution was shown to contain silver nanoparticles when subjected to Energy Dispersion Spectroscopy. This study proved that the effect of sunlight irradiation on Lactobacillus mediated synthesis of silver nanoparticles is energy efficient and inexpensive. Keywords: Silver nanoparticles; UV-Visible Spectrophotometry; Dynamic Light Scattering; Transmission Electron Microscopy; Energy Dispersion Spectroscopy

Synthesis by picosecond laser ablation of ligand-free Ag and Au nanoparticles for SERS applications

The morphological and optical properties of noble metal nanoparticles prepared by picosecond laser generated plasmas in water were investigated. First, the ablation efficiency was maximized searching the optimal focusing conditions. The nanoparticle size, measured by Scanning Transmission Electron Microscopy, strongly depends on the laser fluence, keeping fixed the other deposition parameters such as the target to scanner objective distance and laser repetition frequency. STEM images indicate narrow gradients of NP sizes. Hence the optimization of ablation parameters favours a fine tuning of nanoparticles. UV-Visible spectroscopy helped to determine the appropriate laser wavelength to resonantly excite the localized surface plasmon to carry out Surface Enhanced Raman Scattering (SERS) measurements. The SERS activity of Ag and Au substrates, obtained spraying the colloids synthesized in water, was tested using crystal violet as a probe molecule. The good SERS performance, observed at excitation wavelength 785 nm, is attributed to aggregation phenomena of nanoparticles sprayed on the support.

Facile Synthesis Route of Au-Ag Nanostructures Soaked in PEG

A nanostructured gold-silver soaked in polyethylene glycol 400 (Au-Ag@PEG) is designed using gold(I) chloride and silver nitrate (AgNO3) as precursors and, polyethylene glycol 400 (PEG) as capping agent. The result of the structure characterization using Selected Area Electron Diffraction (SAED) has showed that the synthesized nanomaterial has a good crystallinity while Transmission Electron Microscopy (TEM), energy dispersive X-ray spectrometry (EDX) and Dynamic Light Scattering (DLS) measurements suggest mixed Au-Ag nanoparticles with an average diameter size of around 7 nm and 30 nm for Au and Ag respectively.

Reduction of Instrumental Background Signal of Small Angle X-ray Scattering Measurement at BL19B2

Reduction of Instrumental Background Signal of Small Angle X-ray Scattering Measurement at BL19B2

Improvement of Signal of X-ray Small Angle Scattering Measurement at BL19B2 Installing Horizontal Focusing Mirror II

Improvement of Signal of X-ray Small Angle Scattering Measurement at BL19B2 Installing Horizontal Focusing Mirror II

Underlying Event and Double Parton Scattering Measurements at CMS

Recent results on the double parton scattering studies and measurement of the underlying event activity, performed using proton-proton collisions data collected using the CMS detector are presented. Comparisons to previous results at different center of mass energies are also reported.

Reduction of Background Noise in Wide-angle X-ray Scattering Measurement at BL40B2

Reduction of Background Noise in Wide-angle X-ray Scattering Measurement at BL40B2

Improvement of Signal of X-ray Small Angle Scattering Measurement at BL19B2 Installing Horizontal Focusing Mirror

Improvement of Signal of X-ray Small Angle Scattering Measurement at BL19B2 Installing Horizontal Focusing Mirror

Saturation of tungsten surfaces with hydrogen: A density functional theory study complemented by low energy ion scattering and direct recoil spectroscopy data

Herein, we investigate the saturation limits of hydrogen on the (110) and (100) surfaces of tungsten via Density Functional Theory (DFT) and complement our findings with experimental measurements. We present a detailed study of the various stable configurations that hydrogen can adopt upon the surfaces at coverage ratios starting below 1.0, up to the point of their experimental coverage ratios, and beyond. We provide the many low-energy configurations that exist at all coverages along with the energy landscape they form. Our findings allow us to estimate that the saturation limit on each surface exists with one monolayer of hydrogen atoms adsorbed. In the case of (110) this corresponds to a coverage ratio of one hydrogen atom per tungsten atom, while in the case of (100) a full monolayer is present at a coverage ratio of 2.0 hydrogen atoms per tungsten atoms. Preliminary Low Energy Ion Scattering (LEIS) and Direct Recoil Spectroscopy (DRS) measurements complement this work on the W(110) surface. These results and some previously published measurements obtained on the W(100) surface confirm the findings obtained by DFT. In particular, the saturation limits on each surface, the preferred adsorption sites on both surfaces up to saturation, and the reconstruction of the bare and unsaturated (100) surface.