Colloidal Samples Research Articles

(Invited) Energy Transfer in Hybrid Plasmonic-Polymer Nanomaterials

Energy transfer between plasmonic nanoparticles and polymer acceptors is a possible means to overcome fast competing processes such as rethermalization. I will discuss recent work in which we showed that polyaniline (PANI), which readily hybridizes onto gold nanorods (AuNRs), undergoes switchable energy transfer when the PANI chemical structure is modulated between its emeraldine base and salt forms. Energy transfer had not previously been identified as a mechanism in this common hybrid nanomaterial, despite the fact that AUNR/PANI hybrids have been widely studied for refractive index switching. Because energy transfer depends strongly on spectral overlap between the donor (AuNR plasmon) and the acceptor (PANI absorption) spectra, small changes in overlap within a heterogeneously broadened colloidal sample are enough to obscure the effect in ensemble spectroscopy. Single-particle scattering studies exploit the innate heterogeneity of AuNR/PANI samples because we were able to examine the spectral overlap 1 hybrid at a time and show that strong energy transfer can occur when overlap is maximized in either the emeraldine base or salt forms. Thus, the small differences in AuNR/PANI structure turn out to be an advantage when we look one hybrid at a time.

Mechanistic insight into the colloidal gas aphrons stability in the presence of petroleum hydrocarbons

This study is primarily focusing on the development, generation, and characterization of a colloidal dispersion of microbubbles, known as colloidal gas aphrons as an effective flushing/invading agent during subsurface processes. A major challenge facing the subsurface applications of such colloidal systems, for example for the in-situ remediation of petroleum hydrocarbons contaminated soils or enhanced oil recovery, is the influence of petroleum constituents on colloidal gas aphrons’ structure, consequently their stability. To investigate this issue which was not considered before, first, a series of bulk-scale experiments to study and optimize the properties of colloidal gas aphrons in terms of chemical formulation, structure, stability, the size distribution of bubbles, and gas content were designed and conducted. Then, the effect of the presence of two types of hydrocarbons, namely asphaltenic crude oil, and kerosene, on colloidal gas aphrons’ properties was evaluated. Results show that the unique multilayer structure of the colloidal gas aphrons developed in this research prevents the severe entry and spread of petroleum hydrocarbons into and on the layers of this colloidal system and provides proper colloidal stability than conventional foams in the presence and absence of petroleum hydrocarbons. In the absence of petroleum hydrocarbons, the best colloidal gas aphrons sample had a half-life time of 1621.9 min. The value decreased to 1302.6 min and 699.7 min when crude oil and kerosene were present, respectively. Generally, the results reveal that colloidal gas aphrons’ stability is not considerably influenced by the presence of petroleum constituents, and this suggested colloidal dispersion could be a viable alternative to conventional foams and other chemical-based strategies used in subsurface processes.

Genotoxicity and heating Performance of VxFe3-xO4 nanoparticles in Health applications

The applications of magnetic nanoparticles (MNPs) as biocatalysts in different biomedical areas have been evolved very recently. One of the main challenges in this field is to design affective MNPs surfaces with catalytically active atomic centres, while producing minimal toxicological side effects on the hosting cell or tissues. MNPs of vanadium spinel ferrite (VFe2O4) are a promising material for mimicking the action of natural enzymes in degrading harmful substrates due to the presence of active V5+ centres. However, the toxicity of this material has not been yet studied in detail enough to grant biomedical safety. In this work, we have extensively measured the structural, compositional, and magnetic properties of a series of VxFe3-xO4 spinel ferrite MNPs to assess the surface composition and oxidation state of V atoms, and also performed systematic and extensive in vitro cytotoxicity and genotoxicity testing required to assess their safety in potential clinical applications. We could establish the presence of V5+ at the particle surface even in water-based colloidal samples at pH 7, as well as different amounts of V2+ and V3+ substitution at the A and B sites of the spinel structure. All samples showed large heating efficiency with Specific Loss Power values up to 400 W/g (H0 = 30 kA/m; f = 700 kHz). Samples analysed for safety in human hepatocellular carcinoma (HepG2) cell line with up to 24h of exposure showed that these MNPs did not induce major genomic abnormalities such as micronuclei, nuclear buds, or nucleoplasmic bridges (MNIs, NBUDs, and NPBs), nor did they cause DNA double-strand breaks (DSBs) or aneugenic effects—types of damage considered most harmful to cellular genetic material. The present study is an essential step towards the use of these type of nanomaterials in any biomedical or clinical application.

Experimental study of confined diffusion of rough and smooth ellipsoidal colloids

The study of diffusion in complex confined environments has received great attention in the field of condensed matter physics. The emergence of colloidal systems provides an excellent experimental model system for quantitatively studying the confined diffusion of microscopic particles. When colloidal particles change from spherical to ellipsoidal shape, the system presents anisotropic diffusion dynamics. Recent studies have found that rough surfaces, another important physical parameter of colloids, can lead to unusual rotational dynamics in spherical colloidal systems. However, due to the lack of a suitable experimental system, little is known about the effect of rough surfaces on the confined diffusion of ellipsoidal colloidal particles. In this work, rough colloidal spheres, rough colloidal ellipsoids, and smooth colloidal ellipsoids are prepared, and then monolayer colloidal samples are prepared to study the confined diffusions of these two types of ellipsoids in dense packing of the rough sphere colloids. By calculating the mean square displacement, intermediate self-scattering function, and orientation correlation function of the ellipsoids, we quantitatively characterize the diffusion dynamics of rough and smooth ellipsoids in varying concentrations of rough spheres. The results indicate that the translational diffusion and rotational diffusion of rough ellipsoids and smooth ellipsoids slow down as the concentration of rough spheres increases. This is due to the confinement of the ellipsoid by the surrounding spheres. At low stacking fractions of spheres, smooth and rough ellipsoids show similar translational diffusion and rotational diffusion. However, as the stacking fraction of spheres increases, there is a significant difference in advection diffusion between rough ellipsoids and smooth ellipsoids. The advection diffusion of rough ellipsoids is significantly slower than that of smooth ellipsoids. This is because the rough surface strongly inhibits rotation, meaning that the rotational diffusion of the rough ellipsoids is significantly slower than that of the smooth ellipsoids. By extracting the diffusion coefficients for translation and rotation from the ellipsoid's long-time mean-square displacements, we find that at <i>ϕ</i> = 0.60 and 0.65, the diffusion coefficients of rough ellipsoids are smaller than those of smooth ellipsoids. The translational diffusion coefficient of the rough ellipsoids is notably smaller than that of the smooth ellipsoids. However, the rotation diffusion coefficient of the rough ellipsoids is not significantly different from that of the smooth ellipsoids. This suggests that the rough surface mainly affect translational diffusion, strongly suppressing the translational diffusion of the ellipsoids. By calculating the displacement probability distribution for ellipsoidal motion, we find that at <i>ϕ</i> = 0.65, the translational displacements of rough ellipsoids have a relatively narrow distribution. This suggests that the translational motion of particles is suppressed by the rough surface. However, the distributions of rotation displacement for smooth ellipsoids and rough ellipsoids are very similar, indicating that the rough surface has less influence on particle rotation. At <i>ϕ</i> = 0.74, the rough surface suppresses both the translation and the rotation of the ellipsoid, resulting in a narrower displacement distribution than in the case of smooth ellipsoid. These findings suggest that rough surfaces significantly impede ellipsoidal diffusion, leading the translational and rotational motions not to occur simultaneously. This study provides an in-depth understanding of the role of rough surfaces of colloidal particles in confined diffusion, as well as an experimental basis for explaining the diffusion laws of rough materials.

Higher or Lower? - The Resolution of Analytical Pipelines for the Evaluation of Lipid Nanoparticle Critical Quality Attributes

Dynamic light scattering (DLS) is a routinely used analytical technique to measure the size distribution of a colloidal sample. Nanoparticle tracking analysis (NTA) has more recently emerged as an orthogonal technique to determine particle size and estimated concentration, although widespread use of NTA for lipid nanoparticle (LNP) analysis is not reported. Here, we use DLS and NTA to screen the stability of oligonucleotide drug loaded lipid nanoparticles (oligo-LNPs) at ultra low storage temperatures (-80 °C) in the presence and absence of a cryoprotectant (20 % sucrose, w/v) as a case study to highlight differences in technique resolution. NTA was able to detect additional LNP subpopulations samples for all measured samples, whereas DLS was unable to detect these subpopulations. Our study conveys that the use of orthogonal sizing techniques can support early stage product development, where a more in-depth analysis of formulation and process parameters on LNP stability would support comprehensive understanding of variable defining product stability.

Kaolin-based stable colloidal nano-silica: Peptization factors and stability assessments via designed experiments

This study aims to synthesize stable colloidal silica via the peptization method as a green and low-cost route. It is crucial to adopt a proper synthesis procedure and choose an appropriate raw material. To achieve this purpose, kaolin was employed as a silica rich source that occurs abundantly in nature. The process involves synthesis of the wet gel through the succession of calcination, acid leaching, alkaline treatment, sodium silicate precipitation, and then peptization of the wet gel. Effect of the acid type on acid leaching was evaluated. Effective factors affecting the gel purity such ad acid concentration, pH of gelation, and temperature of alkaline treatment, were studied and optimized via a statistical design of the experiments. Subsequently, the influential parameters on stability and particle size of the obtained colloidal silica, including the temperature of the gel formation, pH of sol medium, concentration of silica gel, and type of stabilizing base, were investigated via one-facto-at-a-time. The samples were characterized by X-ray fluorescence analysis (XRF), dynamic laser light scattering analysis (DLS), X-ray Diffraction (XRD), Fourier transform infrared (FTIR), Brunauer–Emmett–Teller (BET), and Field emission scanning electron microscopy (FESEM) analyses. Results showed that under optimum conditions, ultra-pure silica gel with a silica content of 99.34 % was obtained. The colloidal sample with the highest stability (zeta potential of −75.6 mV), had nanoparticles showing sizes in the range of 21–66 nm.

Structure and Chemical Composition of Soil C-Rich Al-Si-Fe Coprecipitates at Nanometer Scale.

Soil carbon stabilization is mainly driven by organo-mineral interactions. Coprecipitates, of organic matter with short-range order minerals, detected through indirect chemical extraction methods, are increasingly recognized as key carbon sequestration phases. Yet the atomic structure of these coprecipitates is still rather conceptual. We used transmission electron microscopy imaging combined with energy-dispersive X-ray and electron energy loss spectroscopy chemical mappings, which enabled direct nanoscale characterization of coprecipitates from Andosols. A comparison with reference synthetic coprecipitates showed that the natural coprecipitates were structured by an amorphous Al, Si, and Fe inorganic skeleton associated with C and were therefore even less organized than short-range order minerals usually described. These amorphous types of coprecipitates resembled previously conceptualized nanosized coprecipitates of inorganic oligomers with organics (nanoCLICs) with heterogeneous elemental proportions (of C, Al, Si, and Fe) at nanoscale. These results mark a new step in the high-resolution imaging of organo-mineral associations, while shedding further light on the mechanisms that control carbon stabilization in soil and more broadly in aquatic colloid, sediment, and extraterrestrial samples.

Ag@Fe3O4-coated U-shaped plastic optical fiber sensor for H2S detection

This work presents the fabrication of U-shaped plastic optical fiber (POF) sensors for hydrogen sulfide (H2S) detection, coated with Fe3O4 nanoparticles synthetized using the Pulsed Laser Ablation in Liquid (PLAL) technique. The Fe3O4 nanoparticles were synthetized in ultra-pure water and in silver nitrate solution, resulting in two colloidal samples with different morphological, optical, and structural properties. The Fe3O4 nanoparticles were coated onto one POF sensor, while the other sensor was coated with a nanostructure composed of Ag as the core and Fe3O4 as the shell (Ag@Fe3O4). The performance of both sensors was evaluated by exposing them to different concentrations of H2S and other gases such as CH4, H2, and CO2. All experiments were conducted at 25 °C. Results showed that the sensor coated with Ag@Fe3O4 was 12 times more sensitive to H2S compared to the sensor coated with Fe3O4, with a detection limit of 1 ppm and a rise time of 15 s. Moreover, the POF sensor coated with Ag@Fe3O4 presented high selectivity to H2S, making it a promising candidate for H2S detection in different applications. The sensor's performance was also evaluated with a relative humidity range of 20–90%, exhibiting a minimal 0.75% signal variation at 90% humidity.

Phase diagrams and property of colloidal systems prepared with an alkyl polyglucoside surfactant and the essential oil of Melaleuca alternifolia (tea tree)

BackgroundThe purpose of this study was to develop the colloidal formulation, based on microemulsions and hydrogels, of Melaleuca alternifolia oil (aka tea tree oil, TTO) using a sustainable and biocompatible alkyl polyglucoside (APG) surfactant, Glucopon 600 CSUP (G600), commonly formulated for personal-care and home-care products. MethodsThe pseudo-ternary phase diagram of TTO-mixed surfactant-water was established with the water titration method at 25 °C. The mixed surfactants were composed of G600 and propylene glycol (PPG) as a co-surfactant at G600/PPG = 1/1, 2/1 and 3/1 (m/m). Colloid samples of one phase were further characterized with rheological measurements and dynamic light scattering (DLS) at 25 °C. Significant findingsThe samples containing TTO/mixed surfactant = 1/9 (m/m) and water show single phase only. With increasing water contents, the aforesaid system changed from Newtonian to pseudo-plastic, reflecting the transition from micellar solution / microemulsion to hydrogel. Especially, the gel-like behavior was confirmed with the dynamic oscillatory measurements, in which storage moduli were always larger than loss moduli at any time and any frequency under a constant strain of 0.5 %. Microemulsions made of 1 wt% tea tree oil and 9 wt% mixed surfactants were stable for > 1 month as monitored by aggregate size by DLS.

SERS evidence of urea‐disordered G‐quadruplex structure

AbstractStructural changes of the human telomeric d(TTAGGG)4 sequence (Tel24) in the presence of sodium ions and urea were studied using SERS spectroscopy. The SERS spectra indicated that Tel24 (4 × 10−5 mol/l) formed an anti‐parallel G‐quadruplex in a medium containing Na+ ions (100 mmol/l), which was disrupted by the subsequent addition of urea (7.2 mol/l). Intensity ratios of SERS bands originating from breathing vibrations of adenine (~730 cm−1) and guanine (~660 cm−1) rings clearly pointed to the urea‐induced unfolding of G‐quadruplex. In addition, SERS bands assigned to guanine implied the breaking of Hoogsteen hydrogen bonds, most likely due to the bonding of guanine bases with the urea molecules. Considering various experimental conditions applied, the structure‐related SERS response was more pronounced in the silver than in the gold colloid as well as upon NIR (785 nm) rather than Vis (532 nm) laser excitation. The CD spectra of the same colloidal samples supported structural changes of Tel24 obtained by SERS.

Spatial Differentiation Characteristics and Evaluation of Cu and Cd in Paddy Soil around a Copper Smelter.

To accurately evaluate the distribution and bioavailability of potentially toxic elements (PTEs) such as Cu and Cd in farmlands near a copper smelter, we determined the total concentrations (Cu-T and Cd-T), various speciation concentrations of Cu and Cd and physicochemical properties of 18 paddy soil (or colloid) samples in Guixi town, Jiangxi province, China. The results showed that the concentrations of Cu-T and Cd-T in the soil around the smelter far exceeded the standard limits. Specifically, Cu ranged from 97.47 to 1294.63 mg·kg-1, with a coefficient of variation (CV) of 0.95; Cd ranged from 0.14 to 9.06 mg·kg-1, and the CV was 1.68. Furthermore, the pollution of PTEs continued to accumulate, posing a significant risk to the environment and human health. The findings from the analysis of soil and colloid indicated that the distribution characteristics of Cu and Cd speciations did not align with the total concentrations. The highest pollution points were found to be shifted to the residual fraction of Cu, organic fraction, and crystalline iron oxide fraction of Cd in soil. The dominant fraction of Cu in colloid was the amorphous iron oxide fraction, whereas Cd was the crystalline iron oxide fraction. The assessment of Cu and Cd migration (MR) revealed that Cd posed a greater ecological risk. Further examination of the properties of iron oxides in soil and colloid revealed that they played a crucial role in the migration and transformation of soil PTEs.

Composition-Defined Optical Properties and the Direct-to-Indirect Transition in Core-Shell In1-xGaxP/ZnS Colloidal Quantum Dots.

Semiconductors are commonly divided into materials with direct or indirect band gaps based on the relative positions of the top of the valence band and the bottom of the conduction band in crystal momentum (k) space. It has, however, been debated if k is a useful quantum number to describe the band structure in quantum-confined nanocrystalline systems, which blur the distinction between direct and indirect gap semiconductors. In bulk III-V semiconductor alloys like In1-xGaxP, the band structure can be tuned continuously from the direct- to indirect-gap by changing the value of x. The effect of strong quantum confinement on the direct-to-indirect transition in this system has yet to be established because high-quality colloidal nanocrystal samples have remained inaccessible. Herein, we report one of the first systematic studies of ternary III-V nanocrystals by utilizing an optimized molten-salt In-to-Ga cation exchange protocol to yield bright In1-xGaxP/ZnS core-shell particles with photoluminescence quantum yields exceeding 80%. We performed two-dimensional solid-state NMR studies to assess the alloy homogeneity and the extent of surface oxidation in In1-xGaxP cores. The radiative decay lifetime for In1-xGaxP/ZnS monotonically increases with higher gallium content. Transient absorption studies on In1-xGaxP/ZnS nanocrystals demonstrate signatures of direct- and indirect-like behavior based on the presence or absence, respectively, of excitonic bleach features. Atomistic electronic structure calculations based on the semi-empirical pseudopotential model are used to calculate absorption spectra and radiative lifetimes and evaluate band-edge degeneracy; the resulting calculated electronic properties are consistent with experimental observations. By studying photoluminescence characteristics at elevated temperatures, we demonstrate that a reduced lattice mismatch at the III-V/II-VI core-shell interface can enhance the thermal stability of emission. These insights establish cation exchange in molten inorganic salts as a viable synthetic route to nontoxic, high-quality In1-xGaxP/ZnS QD emitters with desirable optoelectronic properties.

Micropillar compression of Ti(C,N)-FeNi cermets: Microstructural, processing, and scale effects

The influence of microstructure and processing route on the small-scale mechanical response as well as on the deformation and failure mechanisms of Ti(C,N)-FeNi cermets were investigated by uniaxial compression of micropillars milled by focused ion beam with different sizes. Stress-strain curves were determined and associated deformation mechanisms were observed in-situ using scanning electron microscopy. The appropriate micropillars dimension was assessed, based on the microstructural characteristics of studied cermets, to overcome scale effect issues. A direct relationship was observed between yield strength and ceramic/metal ratio for colloidal samples. Meanwhile, deformation of metallic binder and glide between Ti(C,N)/Ti(C,N) particles were evidenced as dominant mechanisms during the compression for colloidal cermets with 70 and 80 vol% of ceramic phase, respectively. The obtained results illustrate that samples processed from powder attained by colloidal route provide superior mechanical behavior, as compared to that exhibited by specimens shaped following a conventional powder metallurgy one (wet ball-milling/drying).

Molecular Modulator Approach for Controlling the Length of Chiral 1D Single-Helical Gold Nanoparticle Superstructures.

Peptide-based methods have proven useful for constructing helical gold nanoparticle superstructures that exhibit strong plasmonic chiroptical activity. Superstructure syntheses using the amphiphilic peptide conjugate C16-(AYSSGAPPMoxPPF)2 typically yield 1D helices with a broad length distribution. In this study, we introduce a molecular modulator approach for controlling helix length. It represents a first step toward achieving narrowly disperse populations of single helices fabricated using peptide-based methods. Varying amounts of modulator, C16-(AYSSGA)2, were added to C16-(AYSSGAPPMoxPPF)2-based single-helix syntheses, resulting in decreased helix length and narrowing of the helix length distribution. Kinetic studies of fiber assembly were performed to investigate the mechanism by which the modulator affects helix length. It was found that the modulator leads to rapid peptide conjugate nucleation and fiber growth, which in turn results in large amounts of short fibers that serve as the underlying scaffold for the single-helix superstructures. These results constitute important advances toward generating monodisperse samples of plasmonic helical colloids.

Anti-counterfeiting ink based on polymer nanoparticles containing spiropyran and Aza-BODIPY for artificial industries

Counterfeiting in various artificial industries has been a serious challenge for the authenticity of cultural products. Security marking of original crafts with high-security anti-counterfeiting inks could be a possible way to limit counterfeiting in art products. In this study, spiropyran-containing colloidal polymer particles were synthesized using emulsifier-free emulsion polymerization. Scanning electron microscopy and dynamic light scattering were used to analyze morphology and size of the nanoparticles. Anti-counterfeiting inks based on Förster resonance energy transfer (FRET) were then formulated via physical doping of aza-BODIPY into the colloidal polymer latex samples, where the cemically incorporated spiropyran into the particles acts as the donor and aza-BODIPY plays the role of the acceptor. Fluorescence and ultraviolet-visible spectroscopy were used to evaluate the FRET process possibility and efficiency. The high-security ink was subsequently used for security marking of a special handicraft. Silk fibers were impregnated with both of the photochromic and FRET-based inks in different concentrations and used in weaving the petal patterns. This aqueous FRET-based ink could also be used for security marking of different documents and also various art products. This study could help to reduce forgery in artificial industries, for authentication of the original handicrafts form the fakes, and prevent from counterfeiting in art industries.

Laser scattering centrifugal liquid sedimentation method for the accurate quantitative analysis of mass-based size distributions of colloidal silica.

This paper proposes a laser scattering centrifugal liquid sedimentation (LS-CLS) method for the accurate quantitative analysis of the mass-based size distributions of colloidal silica. The optics comprised a laser diode light source and multi-pixel photon-counting detector for detecting scattered light intensity. The unique optics can only detect the light scattered by a sample through the interception of irradiated light. The developed centrifugal liquid sedimentation (CLS) method comprised a light-emitting diode and silicon photodiode detector for detecting transmittance light attenuation. The CLS apparatus could not accurately measure quantitative volume- or mass-based size distribution of poly-dispersed suspensions, such as colloidal silica, because the detecting signal includes both transmitted and scattered light. The LS-CLS method exhibited improved quantitative performance. Moreover, the LS-CLS system allowed the injection of samples with concentrations higher than that permitted by other particle size distribution measurement systems with particle size classification units using size-exclusion chromatography or centrifugal field-flow fractionation. The proposed LS-CLS method achieved an accurate quantitative analysis of the mass-based size distribution using both centrifugal classification and laser scattering optics. In particular, the system could measure the mass-based size distribution of approximately 20mgmL-1 poly-dispersed colloidal silica samples, such as in a mixture of the four mono-dispersed colloidal silica, with high resolution and precision, thereby demonstrating high quantitative performance. The measured size distributions were compared with those observed through transmission electron microscopy. The proposed system can be used in practical setups to achieve a reasonable degree of consistency for determining particle size distribution in industrial applications.

Photochromic polymer nanoparticles as highly efficient anticounterfeiting nanoinks for development of photo-switchable encoded tags

• Synthesis of colloidal nanoparticles with different polarity and particle size, • Preparation of spiropyran-containing photochromic colloidal nanoparticles, • Effect of polarity on the fluorescence emision and photochromism of colloidal nanoparticles, • Development of the photochromic colloidal nanoparticles as anticounterfeiting nanoinks, • Application of the smart nanoinks for encrypting security documents. Dual photochromic and photoluminescent latex nanoparticles were synthesized to develop innovative anticounterfeiting nanoinks with applications in encryption technology. The colloidal nanoparticles bearing hydroxyl groups were resulted from semi-continuous miniemulsion copolymerization of 2-hydroxyethyl methacrylate and methyl methacrylate. Investigation of the particle size determination and microscopic analysis results demonstrated spherical morphologies for the latex nanoparticles with a mean size of about 80 nm and narrow size distribution. Modification of the polymer nanoparticles with hydroxyl functional groups led to the formation of a high level of hydrogen bonding between the hydroxyl groups and spiropyran chromophore, which is an advantage in the preparation of security anticounterfeiting nanoinks. In addition, optical analysis of the photochromic latex samples showed various UV-vis spectra, fluorescence emission, kinetics of isomerization, and photo-fatigue resistance depending on different amounts of the polar monomers. Further investigations on optical properties exhibited that reducing the size of the colloidal samples can affect their photoluminescence characteristics. This is an efficient way to provide remarkable photoreversible anticounterfeiting inks for different applications, such as printed photo-marking, rewritable handwriting patterns, security encoded tags, and labeling.

Preparation and Characterization of Silver Nanoparticles (AgNPs) by Pulsed Laser Ablation in Liquid

In this study, the technique of pulsed laser ablation in liquid (PLAL) is used to prepare colloidal silver (Ag) nanoparticles in distilled water (D.W.). The optical properties and the synthesis of the nanoparticles are characterized by UV-visible spectrophotometer, photoluminescence (PL), infrared Fourier transforms (FT-IR), and transmission electron microscopy (TEM) measurement. The optical characteristics of (Ag) nanoparticles are investigated using (UV–vis) analysis on all colloidal samples, which reveal a large peak at wavelengths of (405–410 nm) for silver nanoparticles created using PLAL technology. The infrared Fourier transforms (FT-IR) study determines the functional groups of silver nanoparticles in D.W. The silver nanoparticles (AgNPs) have a spherical form, and their diameters range from 12 to 20 nm, according to the transmission electron microscopy (TEM) measurements. The photoluminescence (PL) data reveal two peaks, one in the visible region, which is responsible for the production of silver nanoparticles, and the other in the UV region, where the size of the nanoparticles grows as the number of laser pulses increases.

Extracting Information and Enhancing the Quality of Separation Data: A Review on Chemometrics-Assisted Analysis of Volatile, Soluble and Colloidal Samples

Instrument automation, technological advancements and improved computational power made separation science an extremely data-rich approach, requiring the use of statistical and data analysis tools that are able to optimize processes and combine multiple outputs. The use of chemometrics is growing, greatly improving the ability to extract meaningful information. Separation–multidetection generates multidimensional data, whose elaboration should not be left to the discretion of the operator. However, some applications or techniques still suffer from the lack of method optimization through DoE and downstream multivariate analysis, limiting their potential. This review aims at summarizing how chemometrics can assist analytical chemists in terms of data elaboration and method design, focusing on what can be achieved by applying chemometric approaches to separation science. Recent applications of chemometrics in separation analyses, in particular in gas, liquid and size-exclusion chromatography, together with field flow fractionation, will be detailed to visualize the state of the art of separation chemometrics, encompassing volatile, soluble and solid (colloidal) analytes. The samples considered will range from food chemistry and environmental chemistry to bio/pharmaceutical science.

Coherence properties from speckle contrast analysis at the European XFEL

We show the results of speckle contrast analysis at the MID instrument of European XFEL in the hard X-ray regime. Speckle patterns measured from static colloidal samples are compared to results previously obtained at the SPB/SFX instrument. A high degree of coherence of 0.79 is obtained by modelling the q-dependence of the speckle contrast, that corresponds to a number of coherent modes of M = 1.7. Furthermore, the variation of contrast over many pulse trains is exceptional low, resulting in a degree of coherence with a relative standard deviation below 0.1. Our results demonstrate the high stability of coherence properties at European XFEL over many X-ray pulses and pulse trains which is a prerequisite for coherence-based techniques such as MHz X-ray photon correlation spectroscopy.