Search

The recent advancements in neutron scattering technologies in China, with the development of China's first Spin-Echo Small-Angle Neutron Scattering (SESANS) spectrometer at China Mianyang Research Reactor (CMRR) and the integration of a Very Small Angle Neutron Scattering (VSANS) instrument at China Spallation Neutron Source (CSNS), have significantly bolstered the nation's scientific capabilities. This review aims to highlight the distinctive features and applications of SESANS and SANS, and to offer a valuable contribution by demonstrating how SESANS and SANS can be leveraged for the study of soft matters and solid-state materials, with a particular emphasis on the benefits of techniques such as chain labeling, contrast variation, and contrast matching. We also aim to illustrate what types of information can be gleaned from these methods. The review is structured to first introduce the general concepts of SANS and SESANS, followed by a discussion on the information these techniques can provide. Then the applications of these techniques, in combination with other techniques, on various material investigations will be demonstrated. The review concludes with a summary and future perspectives, aiming to inspire further interdisciplinary research and collaboration, and beneficial to a broader audience. [ABSTRACT FROM AUTHOR]

[Display omitted] Poly(N -isopropylacrylamide) [PNIPAM]-grafted cellulose nanofibers (CNFs) are new thermo-responsive hydrogels which can be used for a wide range of applications. Currently, there is no clear understanding of the precise mechanism by which CNFs and PNIPAM interact together. Here, we hypothesize that the physical crosslinking of grafted PNIPAM on CNF inhibits the free movement of individual CNF, which increases the gel strength while sustaining its thermo-responsive properties. The thermo-responsive behaviour of PNIPAM-grafted CNFs (PNIPAM- g -CNFs), synthesized via silver-catalyzed decarboxylative radical polymerization, and PNIPAM-blended CNFs (PNIPAM- b -CNFs) was studied. Small angle neutron scattering (SANS) combined with Ultra-SANS (USANS) revealed the nano to microscale conformation changes of these polymer hybrids as a function of temperature. The effect of temperature on the optical and viscoelastic properties of hydrogels was also investigated. Grafting PNIPAM from CNFs shifted the lower critical solution temperature (LCST) from 32 °C to 36 °C. Below LCST, the PNIPAM chains in PNIPAM- g -CNF sustain an open conformation and poor interaction with CNF, and exhibit water-like behaviour. At and above LCST, the PNIPAM chains change conformation to entangle and aggregate nearby CNFs. Large voids are formed in solution between the aggregated PNIPAM-CNF walls. In comparison, PNIPAM- b -CNF sustains liquid-like behaviour below LCST. At and above LCST, the blended PNIPAM phase separates from CNF to form large aggregates which do not affect CNF network and thus PNIPAM- b -CNF demonstrates low viscosity. Understanding of temperature-dependent conformation of PNIPAM- g -CNFs engineer thermo-responsive hydrogels for biomedical and functional applications. [ABSTRACT FROM AUTHOR]

The saponin β -aescin is well known for its self-aggregation above the critical micelle concentration (cmc) and its interaction with model membranes made of zwitterionic phospholipids including the formation of mixed bicelle systems. In this study, we investigate the interaction of β -aescin with small unilamellar vesicles (SUVs) made of the negatively charged lipid 1,2-dioleoyl-sn-glycero-3-phosphoglycerol (DOPG). The study is conducted at a pH value at which aescin is negatively charged as well, and mixtures up to an aescin content of 50 mol% (equivalent to a molecular ratio of 1:1) were investigated, so that the cmc of aescin is exceeded by far. Analysis of the system by scattering and NMR methods was performed with respect to two reference systems made of the bare components: DOPG SUVs and aescin micelles. Wide-angle X-ray scattering (WAXS) was used to determine molecular correlation distances for both kinds of molecules, and small-angle neutron and X-ray scattering (SANS and SAXS) revealed a structural picture of the system, which was further confirmed by diffusion-ordered nuclear magnetic resonance spectroscopy (DOSY-NMR). Contrary to the expected solubilization of the DOPG membrane, most probably none- or only weakly-interacting, separated DOPG SUVs and aescin micelles were found. The study additionally highlights the importance of using independent methods to characterize a rather complex colloidal system in order to obtain a complete picture of the structures formed. [ABSTRACT FROM AUTHOR]

Block copolymers synthesized via Atom Transfer Radical Polymerization from alkyl acrylate and t-butyl acrylate and the subsequent hydrolysis of the t-butyl acrylate to acrylic acid were systematically varied with respect to their hydrophobic part by the variation in the alkyl chain length and the degree of polymerisation in this block. Depending on the architecture of the hydrophobic part, they had a more or less pronounced tendency to form copolymer micelles in an aqueous solution. They were employed for the preparation of IPECs by mixing the copolymer aggregates with the polycations polydiallyldimethylammonium chloride (PDADMAC) or q-chit. The IPEC structure as a function of the composition was investigated by Static Light and Small Angle Neutron Scattering. For weakly-associated block copolymers (short alkyl chain), complexation with polycation led to the formation of globular complexes, while already existing micelles (long alkyl chain) grew further in mass. In general, aggregates became larger upon the addition of further polycation, but this growth was much more pronounced for PDADMAC compared to q-chit, thereby leading to the formation of clusters of aggregates. Accordingly, the structure of such IPECs with a hydrophobic block depended largely on the type of complexing polyelectrolyte, which allowed for controlling the structural organisation via the molecular architecture of the two oppositely charged polyelectrolytes. [ABSTRACT FROM AUTHOR]

Contrast matching by isotopic exchange in cellulose allows visualizing functional groups, biomolecules, polymers and nanoparticles embedded in cellulosic composites. This isotopic exchange varies the scattering length density of cellulose to match its contrast with the background network. Here, contrast matching of microcrystalline-cellulose (MCC) and the functionalized nanocellulose-fiber (CNF) and cellulose nanocrystals (CNC) are elucidated by small angle neutron scattering (SANS). Results show no isotopic exchange occurs for the CNF surface functionalized with carboxyl nor for the CNC- High with a high sulfate groups concentration. Both CNC- Low , with low sulfate groups, and MCC exchange 1H with 1D in D 2 O. This is due to the high exchange probability of the labile C 6 position primary -OH group. The structure of thermo-responsive poly-N-isopropylacrylamide (PNIPAM) chains grafted onto CNF (PNIPAM-grafted-CNF) was extracted by CNF contrast matching near the lower critical solution temperature. Contrast matching eradicates the CNF scattering to retain only the scattering from the grafted-PNIPAM chains. The coil to globule thermo-transition of PNIPAM was revealed by the power law variation from q−1.3 to q−4 in SANS. Isotopic exchange in functionalized cellulosic materials reveals the nano- and micro-scale structure of its individual components. This improved visualization by contrast matching can be extended to carbohydrate polymers to engineer biopharmaceutical and food applications. [Display omitted] [ABSTRACT FROM AUTHOR]

A 9Cr-oxide dispersion strengthened (ODS) steel was thermally aged at 873 K for up to 5000 h. The size distribution and chemical composition of the dispersed oxide nanoparticles were analyzed by small-angle neutron scattering under a magnetic field. Combined with transmission electron microscopy, Vickers micro-hardness tests and electron backscattered diffraction measurements, all the results showed that the thermal treatment had little or no effect on the size distributions and volume fractions of the oxide nanoparticles in the ferromagnetic matrix, which suggested excellent thermal stability of the 9Cr-ODS steel. [ABSTRACT FROM AUTHOR]

Lipid vesicles are widely used as models for cell membranes, hosts for membrane protein studies, and containers for hydrophilic molecules. The vesicle solutions in these applications are usually prepared at a specific lipid concentration; however, because vesicles are solvent-filled structures, the corresponding volume fraction of vesicles is at least a factor of three times higher than the corresponding lipid volume fraction and critically depends on the vesicle radii. Here we show that these higher than may be expected vesicle volume fractions result in measurable interactions between the vesicles as well as affect the vesicle diffusion. We show that vesicle solutions prepared with lipid mass fractions, mL, as low as ≈ 0.004, which correspond to a lipid concentration of ≈ 4 mg/mL or 5 mmol/L (mM), not only have a measurable apparent structure factor (S′(q)) in small angle neutron scattering (SANS) experiments, but that this repulsive structure factor also affects the measured diffusion coefficient at small scattering vectors (q) such as those probed with dynamic light scattering (DLS). The measured diffusion coefficients are further affected by indirect solvent mediated interactions described by a hydrodynamic factor (H(q)). Accounting for the concentration-dependence of the vesicle diffusion shows that the lipid concentration dependence measured in neutron spin echo (NSE) spectroscopy is due to differences in the effective vesicle diffusion coefficients and not the membrane fluctuation dynamics. The results have practical implications for static and dynamic scattering experiments as well as provide interesting insights into the interactions between soft lipid vesicles.

[Display omitted] Membrane structuration of Large Hybrid Unilamellar Polymer/Lipid Vesicle (LHUV) is an important parameter on the optimization of their properties and thus their valuation in various fields. However, this kind of information is hardly accessible. In this work, we will focus on the development of LHUV obtained from the self-assembly of diblock poly(dimethylsiloxane)- b -poly(ethylene oxide) (PDMS- b -PEO) of different molar masses combined with 1-palmitoyl-2-oleoyl- sn - glycero -3-phosphocholine (POPC) at 15% and 25% w/w content. The hybrid character of the resulting vesicles as well as their membrane structure are characterized by the mean of different techniques such as small-angle neutron scattering (SANS) and cryo-transmission electron microscopy (cryo-TEM). We show that hybrid vesicles with homogeneous membrane structure are obtained whatever the molar mass of the block copolymer (from 2500 to 4000 g/mol), with of a small number of tubular structures observed with the higher molar mass. We also demonstrate that the permeability of the LHUV, evaluated through controlled release experiments of fluorescein loaded in LHUV, is essentially controlled by the lipid/polymer composition. [ABSTRACT FROM AUTHOR]

Cellulosic bioethanol is a promising renewable and substitute source of energy. To make the bioconversion of LCB to fuels cost effective and energy efficient, it is essential to reduce the recalcitrance of LCB and unravel the process of biomass deconstruction. Present study employed sequential dilute acid-alkali pretreatment of sugarcane bagasse (SCB) for enhancing its bioconversion to ethanol. Box-Behnken and D-optimal designs were used to optimise the process of dilute acid and alkali pretreatments sequentially, resulting in an optimum concentration of 3% (v/v) and 5% (w/v) for H 2 SO 4 and NaOH with solid SCB loadings of 18 and 15% (w/w), respectively, for 30 min at 121 °C. The effectiveness of sequential pretreatment was supported by increased cellulose content (83%), drop in hemicellulose, enhanced delignification and 60% enzymatic hydrolysis of SCB by in-house Trichoderma reesei cellulases at enzyme dose of 20 FPU/g. The favourable multi-length scale ultrastructural changes in SCB induced by pretreatment were confirmed by FT-IR, SEM, EDX, TGA, XRD and small angle neutron scattering (SANS). SANS revealed increase in small pore radii from 11.1 to 18.5 Å, indicating improved biomass porosity after sequential pretreatment. Thus, sequential pretreatment of LCB effectively reduced the recalcitrance and could be more useful in lignocellulosic biorefinery applications. Image 1 • 83% cellulose after sequential dilute acid-alkali pretreatment of SCB. • Decreased crystallinity and transition to amorphous cellulose after pretreatment. • SANS employed first time to probe structural changes in SCB. • Increased porosity of sequentially pretreated SCB confirmed by SANS. [ABSTRACT FROM AUTHOR]

The mechanical properties of cemented carbides can be tuned by controlling WC grain coarsening and the simultaneous growth of the binder pocket size during the sintering. So far, bulk studies considering this phenomenon are scarce, but here, we report the first very-small angle neutron scattering (VSANS) study on cemented carbides. VSANS is supplemented with electron backscatter diffraction (EBSD) and the microstructural refinement by increasing V-doping (0, 0.02, 0.22, and 0.76 wt%) is quantified. The capability of VSANS as a non-destructive bulk probe for cemented carbides is shown, paving way for forthcoming in-situ studies. Unlabelled Image [ABSTRACT FROM AUTHOR]

α′ precipitation in a Fe-19 at.%Cr alloy aged at 500 °C up to 2008 h has been characterized by both APT and SANS. This paper shows that when using an appropriate method for SANS data treatment, both APT and SANS yield consistent results regarding not only volume fraction and size but also α and α′ composition. Good agreement is achieved when α′ particles are considered as magnetic scattering features at the early stage of the kinetics. • APT and SANS characterization of α' precipitation in thermally aged Fe19Cr alloys • SANS and APT agreement on α' precipitate composition when α' particles are considered as magnetic scattering features • Confirmation that α' Cr composition evolution with ageing time is not an APT artefact. [ABSTRACT FROM AUTHOR]

[Display omitted] • Synthesis, characterization and applications of novel bisamide and bisurea functionalized benzimidazole compounds. • Probing the mechanism of gelation in both series of compounds using various physicochemical techniques. • Role of bisamide and bisurea functional groups on gelation behaviour is explored. • Bisamide and bisurea compounds displayed highly selective detection of mercury ion in solution. We present a set of alkyl chain functionalized benzimidazole based compounds containing amide and urea functional groups which were screened for their gelation behaviour. Both the sets bear similar molecular scaffolds, making them an excellent tool for determining the role of the supramolecular interactions involved in the gelation process. All the compounds were characterised using physico-chemical techniques like NMR and FT-IR. The gels were subjected to small angle neutron scattering studies (SANS), rheological studies, SEM and FT-IR. In order to rationalize the gelation behaviour, solvent parameter studies were conducted. The results show a dependence on refractive index of solvent, polarizability and dispersion interactions. The respective orientation of amide and conformation in urea based compounds were explored and studied using computational calculations and their corresponding effect on the resulting supramolecular superstructures was scrutinized. The compounds were also explored to act as chemosensor for selective detection of mercuric ions with exceptionally low LOD (limit of detection) values. [ABSTRACT FROM AUTHOR]

Scattering techniques represent non-invasive experimental approaches and powerful tools for the investigation of structure and conformation of biomaterial systems in a wide range of distances, ranging from the nanometric to micrometric scale. More specifically, small-angle X-rays and neutron scattering and light scattering techniques represent well-established experimental techniques for the investigation of the structural properties of biomaterials and, through the use of suitable models, they allow to study and mimic various biological systems under physiologically relevant conditions. They provide the ensemble averaged (and then statistically relevant) information under in situ and operando conditions, and represent useful tools complementary to the various traditional imaging techniques that, on the contrary, reveal more local structural information. Together with the classical structure characterization approaches, we introduce the basic concepts that make it possible to examine inter-particles interactions, and to study the growth processes and conformational changes in nanostructures, which have become increasingly relevant for an accurate understanding and prediction of various mechanisms in the fields of biotechnology and nanotechnology. The upgrade of the various scattering techniques, such as the contrast variation or time resolved experiments, offers unique opportunities to study the nano- and mesoscopic structure and their evolution with time in a way not accessible by other techniques. For this reason, highly performant instruments are installed at most of the facility research centers worldwide. These new insights allow to largely ameliorate the control of (chemico-physical and biologic) processes of complex (bio-)materials at the molecular length scales, and open a full potential for the development and engineering of a variety of nano-scale biomaterials for advanced applications.

The specific spatial and temporal distribution of lipids in membranes play a crucial role in determining the biochemical and biophysical properties of the system. In nature, the asymmetric distribution of lipids is a dynamic process with ATP-dependent lipid transporters maintaining asymmetry, and passive transbilayer diffusion, that is, flip-flop, counteracting it. In this chapter, two probe-free techniques, 1 H NMR and time-resolved small angle neutron scattering, are described in detail as methods of investigating lipid flip-flop rates in synthetic liposomes that have been generated with an asymmetric bilayer composition., (Copyright © 2024. Published by Elsevier Inc.)

Abstract Amphiphilic Pluronic triblock copolymers form various self-assembled structures such as sphere, cylinder, lamellae and so on, depending on temperature, leading to the increase of hydrophobicity of block copolymers. However, the effective molecular volume change of the block copolymer has not been fully exploited yet, when temperature increases. Here, we have investigated the effective molecular volume change of the block copolymer upon heating by using the contrast variation small angle neutron scattering. The scattering length densities (SLDs) of the block copolymer were experimentally obtained from the neutron scattering contrast variation method between the solvent and the block copolymer at varying temperature. Even though the SLD, which is the intrinsic property of the material, should not be changed by temperature elevation, it was dependent on temperature, indicating that the molecular volume is changed. Therefore, we obtained the increase rate of the molecular volume change of the block copolymer (the effective molecular volume change) from the comparison of the calculated SLD and the standard SLD, which is evaluated by plotting the SANS intensity at the first order Bragg peak as the function of temperature at each volume fraction of D 2 O and H 2 O that is about 25.5%–51.3% depending on temperature. [ABSTRACT FROM AUTHOR]

Abstract A new method to easily derive the phase transition of amphiphilic block copolymer in aqueous solution is suggested in this study. Using two kinds of Pluronic triblock copolymers, which have different mass fractions of the hydrophilic part of the block copolymer, the mixed block copolymers in aqueous solution self-assembled into a variety of nanostructures. Small angle neutron scattering revealed that the block copolymer complex formed spheres, cylinders, and vesicles depending on both the concentration of another Pluronic block copolymer (Pluronic PE6200) as an additive and temperature. This phase behavior can be easily explained in terms of the hydrophobicity of the block copolymer by increasing its effective hydrophobic moiety and temperature. [ABSTRACT FROM AUTHOR]

Hypothesis Oleosomes are stabilized by a complex outer phospholipid-protein-layer. To improve understanding of its structure and stabilization mechanism, this shell has to be studied in extracellular native conditions. This should be possible by SANS using contrast variation. Oleosomes are expected to be highly temperature stable, with molecular changes occurring first in the protein shell. Direct measurements of changes in the shell structure are also important for processing methods, e.g. encapsulation. Experiments Extracted soybean oleosomes were studied directly and after encapsulation with pectin by SANS using contrast variation. In order to determine structure and size, a shell model of oleosomes was developed. The method was tested against a simple phospholipid-stabilized emulsion. The oleosomes’ temperature stability was investigated by performing SANS at elevated temperatures. Findings Size ( R g  = 1380 Å) and shell thickness of native and encapsulated oleosomes have been determined. This is the first report measuring the shell thickness of oleosomes directly. For native oleosomes, a shell of 9 nm thickness surrounds the oil core, corresponding to a layer of phospholipids and proteins. Up to 90 °C, no structural change was observed, confirming the oleosomes’ high temperature stability. Successful coavervation of oleosomes was shown by an increase in shell thickness of 10 nm after electrostatic deposition of pectin. [ABSTRACT FROM AUTHOR]

Irradiation effects are studied using accelerated-damage experiments in test reactors and charged-particle accelerator facilities. Neutrons and ions create vacancy and self-interstitial defects, in dose unit of displacements per atom (dpa). It is important to understand the effects of irradiation dose rate on microstructural evolution processes, including irradiation enhanced precipitation, to properly interpret results from experiments using accelerated-damage experiments. Here we report on precipitation in Fe-Cu and Fe-Cu-Mn model alloys irradiated at dose rates ranging from ∼10 −10 dpa/s (neutrons) to ∼10 −5 dpa/s (70 MeV Fe ions). Atom probe tomography, small angle neutron scattering, and rate theory models show that precipitation is affected by both dose rate and alloy composition. Higher dose rates: 1) decrease the efficiency of radiation enhanced diffusion, due to increased vacancy-self interstitial recombination; and, 2) increase the rate of ballistic mixing that partly dissolves the precipitate constituents. The key parameter is the rate of ballistic mixing relative to the rate that solutes are reacquired by diffusion. The Mn in the ternary alloy traps vacancies and enhances recombination, leading to very different precipitate evolution kinetics. [ABSTRACT FROM AUTHOR]

The bake hardening treatment shows great potential for increasing the yield strength of steel components for automotive applications. This study investigates the effects of bake hardening on the yield strength and ductility of an austenitic high‐Mn steel. In order to identify a promising process window, the prestrain, the bake hardening temperature, and the annealing time are varied. The bake hardening effect is evaluated by the uniaxial tensile tests with digital image correlation (DIC) in situ monitoring. The results show strong bake hardening effect on the high‐Mn steel when certain amount of prestrain is applied. Large amounts of prestrain even leads to room temperature aging. Small angle neutron scattering (SANS) measurements indicate the absence of Mn–C short range ordering (SRO) after the prestrain; however, the nano‐sized Mn–C SRO re‐occurs after the annealing. At high prestrain degree, an increase in the number density of the Mn–C SRO is found in both cases, after annealing at elevated temperature and aging at room temperature, indicating an accelerated Mn–C SRO formation. The results suggest that SRO is responsible for an increase in the yield strength and a pronounced yielding of the high‐Mn steel after bake hardening treatment. [ABSTRACT FROM AUTHOR]

Predictive simulations of the γ′ and γ″ precipitates in the nickel-based superalloy Alloy 718 is needed for integrated computational materials engineering of technical components. But so far, no thermo-kinetic model is published for this alloy that is capable of reproducing simultaneously the precipitation evolution during, both, short and long time aging durations for an extended range of temperatures. The thermo-kinetic modeling was performed in the software package MatCalc, which uses the classical nucleation theory, the Svoboda-Fischer-Fratzl-Kozeschnik growth model and the ‘generalized broken bond theory’ for the interfacial energy. A combination of atom probe tomography, electron microscopy, small angle neutron scattering and sequential tensile tests are conducted to obtain the unknown kinetic evolution and strengthening parameters at the nano-, micro- and macro-scales for the model. The role of the physical association of the γ′ and γ″ precipitates and the effects of the precipitation strengthening are discussed. The resulting parametrized model successfully reproduces the measured local chemical composition, volume fractions, mean radii and precipitation strengthening contributions within a single set of model parameters up to 800 °C. Between 800 °C and 830 °C the model slightly over-predicts the kinetics. [ABSTRACT FROM AUTHOR]

Hydrophobically modified polyacrylates (hmPAAs) obtained by Atomic Transfer Radical Copolymerisation (ATRP) of mixtures of different alkyl acrylates and t -butyl acrylate and subsequent hydrolysis of the t -butyl acrylate to polyacrylic acid (PAA), were studied with respect to their aggregation behaviour in aqueous solution. The hydrophobic modifications were long alkyl chains that were varied systematically from dodecyl to stearyl, thereby expecting a strong propensity for hydrophobic aggregation. Their structure in aqueous solution was investigated comprehensively by small-angle neutron scattering (SANS) and complemented by dynamic light scattering (DLS) experiments. In these random copolymers the degree of amphiphilicity and hydrophobicity was varied by the percentage of alkyl chains and pH. Due to the length of the alkyl chain all these copolymers have a tendency for microphase separation, but this tendency and the structure of the formed hydrophobic domains depend in a systematic fashion on the precise molecular composition. The domain size scales with the length of the hydrophobic alkyl modification and, for chains of C 16 and longer, there is apparently a tendency for elongation. Another interesting observation is that for 20 mol% hydrophobic modification rather self-contained and isolated hydrophobic micellar domains are formed. In contrast, the copolymers with 10 mol% alkyl modification contain interconnected hydrophobic domains as evidenced from the low-q scattering seen in SANS and confirmed by DLS observations. This tendency is further enhanced when fully charging the copolymers. In summary, the molecular design of such random amphiphilic copolymers allows in a nice way to control the aggregation state in solution. [ABSTRACT FROM AUTHOR]

In this work a combination of the characterisation techniques small angle neutron scattering (SANS) and atom probe tomography (APT) are used to study the precipitation in a maraging steel. Three similar maraging steel alloys were aged at different temperatures and ageing times, and then characterised using SANS, APT and microhardness. The alloys consist of two types of precipitates, namely Laves phase and β-NiAl, the precipitates have different composition and hence precipitate ageing, which makes it complicated to model. The SANS experimental set-up was relatively simple and allowed the precipitate size and fraction of a large number of samples to be measured in a single experiment. The APT results were used for constraining the SANS modelling, particularly the composition, shape and distribution of phases. The characterisation led to the following description of precipitation: NiAl phase reaches coarsening at early stages of ageing and shifts its strength mechanisms from shearing to Orowan looping, which cause the characteristic peak strength; the Laves phase is in growth throughout and its strength contribution increases with ageing time. These observations were shown to be consistent with precipitate evolution and strengthening models, and the work of others. Although, there are some issues with the combination of SANS and APT approach, which are discussed, the methodology provides a valuable tool to understand complex precipitation behaviours. [ABSTRACT FROM AUTHOR]

The phase behavior of amphiphilic Pluronic block copolymers in aqueous solution is of importance for a broad spectrum of practical applications but has not been fully exploited yet. Here, the phase behavior of the mixture of the Pluronic P65 and P105 triblock copolymer, (which have the same composition of PEO and PPO but the different molecular weight) and organic derivative, 5-methyl salicylic acid (5mS), in aqueous solution has been investigated by using small angle neutron scattering (SANS). According to the temperature and the 5mS concentration, SANS measurements showed that the P65-5mS mixtures sequentially transform into a random coil, sphere, vesicle, cylinder, and vesicle again, while the P105-5mS mixtures form spherical particles with two different sizes without any topological phase transition. Upon heating, the formation of two different kinds of the vesicle structure of amphiphilic block copolymer in aqueous solution is very unusual. This phase behavior was explained as the coupled effect of the simultaneous increase of the hydrophobicity of the polymer and the solubility of 5mS molecules upon heating. This result gives fundamental information for the practical use of Pluronic polymers in nano- and bio-science and it provides a simple route for the fabrication of the nanostructure without a complicated procedure.

Structure transition in triple liquid system D2O-tetradecyltrimethilammonium bromide-NaBr was studied by means of small-angle neutron scattering in a wide range of temperature, pressure and salt concentrations. The phase P-T transition diagrams of colloidal micellar system to the suspension colloidal system with crystallites was construct from experimental data. It is shown that salt concentration increasing causes the shift of the boundary in the direction of higher temperatures and lower pressures. Thermodynamic justification of the received results is represented.

The reactivity of the MgO powder employed in the formulation of Mg–K phosphate ceramics can be modulated through the calcination temperature of MgCO 3 source material, which has a direct impact on production costs. Upon annealing, MgO undergoes sintering, and in order to optimize the design of products for applications, it is of primary importance to disclose the link between the sintering temperature, reaction mechanisms, microstructure and performance in this class of ceramics. Small angle neutron scattering was used to measure the specific surface area of pores in samples aged 30 days produced with 5 different MgO powders, and to follow the evolution of pore size distribution during the setting reaction, in a time-resolved experiment. Quantification of amorphous and crystalline fraction up to 28 days was accomplished in synchronous with flexural strength tests. Results indicate that mechanical properties improve thanks to the progressive buildup of a pervasive network of tabular crystals filling the entire volume. Increasing the sintering temperature above 1500 °C yields a more compact ceramic, with less, but larger, pores, containing more crystalline fraction and less amorphous. This is consistent with the recently proposed mechanisms describing the ceramic setting reaction. The analysis of the fractured surface suggests that strength might be effectively improved modifying the density and orientation of crystals in the ceramic volume, a way for engineering new tailor-made ceramics. [ABSTRACT FROM AUTHOR]

[Display omitted] • ex-situ and in-situ observations from the microscopic to the nanoscopic level. • SPEM and XPS provide insight into the agglomeration of chemical elements during DCT. • Mo plays a crucial role in DCT through its modification of chemical bonding states. • APT shows preferential formation of Mo-rich M 7 C 3 carbides after DCT. • SANS and SPEM confirm increased formation of M 23 C 6 carbides. The study investigates the effect of deep cryogenic treatment (DCT) on a high-alloyed ferrous alloy (HAFA) and its effectiveness on carbide evolution and chemical shifts of alloying elements. With ex-situ and in-situ observations ranging from the microscopic to the nanoscopic level, we uncover the atomistic mechanism by which DCT affects carbide precipitation, resulting in a 50% increase in carbide volume fraction. Synchrotron-based scanning photoelectron microscopy provides insight into the agglomeration of carbon during exposure to DCT. We find that Mo plays a crucial role in DCT through its modification of chemical bonding states, which is postulated to originate from the loosely-formed primordial Mo 2 C carbides formed during exposure to cryogenic temperatures. These in turn provide energetically favorable nucleation zones that accelerate the formation of M 7 C 3 carbides, which serve as intermediate states for the formation of M 23 C 6 carbides, which most strongly impact the mechanical properties. These results are supported by atom probe tomography, showing the preferential formation of Mo-rich M 7 C 3 carbides in DCT samples, resulting from greater solute mobility. This work clarifies the fundamental mechanisms on how DCT affects HAFA, solving a long-elusive problem. [ABSTRACT FROM AUTHOR]

Bulk nanolaminated graphene (reduced graphene oxide, RGO) reinforced Al–Mg–Si composites of various RGO concentrations were fabricated by a modified powder metallurgy method. The RGO incorporation was found to significantly facilitate the precipitation kinetics of the matrix alloy, and change the size and volume fraction of the precipitates in the peak-aged state, as quantified by small angle neutron scattering measurements on bulk specimens. An intermediate RGO concentration of 0.7 wt % in the composite led to a uniform dispersion of RGO layers in the matrix alloy, a refined microstructure, a large dislocation density, considerable Mg segregation at the inter-lamella boundaries, and precipitates that were smaller and of higher volume fraction. These microstructural features rendered a good strength-ductility synergy of 287.5 ± 1.6 MPa uniaxial tensile strength and 9.4 ± 0.2% uniform elongation. [ABSTRACT FROM AUTHOR]

Protein-nucleic acid complexes are involved in all vital processes, including replication, transcription, translation, regulation of gene expression and cell metabolism. Knowledge of the biological functions and molecular mechanisms beyond the activity of the macromolecular complexes can be determined from their tertiary structures. Undoubtably, performing structural studies of protein-nucleic acid complexes is challenging, mainly because these types of complexes are often unstable. In addition, their individual components may display extremely different surface charges, causing the complexes to precipitate at higher concentrations used in many structural studies. Due to the variety of protein-nucleic acid complexes and their different biophysical properties, no simple and universal guideline exists that helps scientists chose a method to successfully determine the structure of a specific protein-nucleic acid complex. In this review, we provide a summary of the following experimental methods, which can be applied to study the structures of protein-nucleic acid complexes: X-ray and neutron crystallography, nuclear magnetic resonance (NMR) spectroscopy, cryogenic electron microscopy (cryo-EM), atomic force microscopy (AFM), small angle scattering (SAS) methods, circular dichroism (CD) and infrared (IR) spectroscopy. Each method is discussed regarding its historical context, advancements over the past decades and recent years, and weaknesses and strengths. When a single method does not provide satisfactory data on the selected protein-nucleic acid complex, a combination of several methods should be considered as a hybrid approach; thus, specific structural problems can be solved when studying protein-nucleic acid complexes., Competing Interests: The manuscript entitled “Structural studies of protein–nucleic acid complexes: a brief overview of the selected techniques”, by Kamil Szpotkowski, Klaudia Wójcik and Anna Kurzyńska-Kokorniak, has not been published and is not under consideration for publication elsewhere. We have no conflicts of interest to disclose., (© 2023 The Author(s).)

ABSTRACT Morphology of the active layer in an organic photovoltaic (OPV) device is known to have a significant impact on the device performance. It is, however, difficult to characterize nanoscale morphologies in detail, especially at the ensemble level. Herein, we report the utilization of small angle neutron scattering (SANS) to investigate variations in the nanoscale morphologies of the active layer of poly(3-hexylthiophene-2,5-diyl):[6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM) bulk heterojunction OPV depending on the composition of casting solvent. Both the power law and the poly hard sphere model were utilized to characterize the state of the donor and acceptor components, respectively, from the obtained SANS data. Furthermore, the relationship between the nanoscale morphology and device performance is outlined. It was found that the use of 2-chlorophenol, a poor solvent for P3HT and, at the same time, a very good solvent for PCBM, leads to nanomorphology featuring ordered, highly crystalline P3HT and small (15.2 nm) PCBM domains. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 128-134 [ABSTRACT FROM AUTHOR]

Precipitate evolution in Ti–5Al–5Mo–5V–3Cr–0.3Fe wt.% (Ti-5553) has been studied in-situ by small angle neutron scattering (SANS) during a two step ageing heat treatment of 300°C/8h+500°C/2 h. The first heat treatment step precipitates ω , with a corresponding increase in hardness of ∼15% compared to quenched material. The second heat treatment step precipitates fine scale α from the ω phase, with a ∼90% increase in hardness compared to quenched material. The SANS measurements are complemented by atom probe tomography (APT) to give compositional information, ex-situ transmission electron microscopy (TEM) to confirm phase identification and size distribution locally, and X-ray diffraction (XRD) for additional confirmation of phase identification. The ω phase is depleted in all the solute additions following 300°C/8 h ageing heat treatment. The volume fraction of the ω phase from APT is estimated to be ∼7%. SANS modelling is consistent with disc shaped particles for the ω phase. The mean particle diameter increases from ∼7.5 nm to 9.5 nm diameter between 1 h and 8 h heat treatment at 300 °C, while the thickness increases from ∼4 nm to ∼5 nm. The SANS model estimates the volume fraction to be ∼10% for the 8 h heat treatment, using the phase compositions from APT. [ABSTRACT FROM AUTHOR]

The use of styrene-maleic acid copolymers (SMAs) to produce membrane protein-containing nanodiscs without the initial detergent isolation has gained significant interest over the last decade. We have previously shown that a Photosystem I SMALP from the thermophilic cyanobacterium, Thermosynechococcus elongatus (PSI-SMALP), has much more rapid energy transfer and charge separation in vitro than detergent isolated PSI complexes. In this study, we have utilized small-angle neutron scattering (SANS) to better understand the geometry of these SMALPs. These techniques allow us to investigate the size and shape of these particles in their fully solvated state. Further, the particle's proteolipid core and detergent shell or copolymer belt can be interrogated separately using contrast variation, a capability unique to SANS. Here we report the dimensions of the Thermosynechococcus elongatus PSI-SMALP containing a PSI trimer. At ~1.5 MDa, PSI-SMALP is the largest SMALP to be isolated; our lipidomic analysis indicates it contains ~1300 lipids/per trimeric particle, >40-fold more than the PSI-DDM particle and > 100 fold more than identified in the 1JB0 crystal structure. Interestingly, the lipid composition to the PSI trimer in the PSI-SMALP differs significantly from bulk thylakoid composition, being enriched ~50 % in the anionic sulfolipid, SQDG. Finally, utilizing the contrast match point for the SMA 1440 copolymer, we also can observe the ~1 nm SMA copolymer belt surrounding this SMALP for the first time, consistent with most models of SMA organization. [Display omitted] • SANS analysis of the largest membrane protein isolated via a SMALP. • Lipidomics reveal PSI-SMALP contains ~1200 lipids per PSI trimer. • Large lipid annulus agrees with the preliminary model based on SANS. • The membrane environment within and surrounding PSI is enriched in SQDG. • The inclusion of the anionic SQDG may explain the faster photochemistry observed in the PSI-SMALP. [ABSTRACT FROM AUTHOR]

Small angle neutron scattering (SANS) was applied to analyze the degradation of an organic coating layer on steel and for the non-destructive evaluation of the corrosion behavior of the coated steels. The steel was a modified AISI 1004 steel with 1.2% aluminum and 0.8% chromium to improve corrosion resistance. The organic coating layer was epoxy primer, which was painted with about 250-μm thickness on the steel. The organic-coated specimen was subjected to wet-and-dry cyclic corrosion conditions for 112 days in artificial sea water at 40°C. The corrosion potential and the corrosion rate of the steel were −1.1 V and 8.8 × 10 A/cm, respectively. SANS spectra showed that nano-sized defects were not formed in the organic layers after the 112-day wet-and-dry corrosion test. Artificial cracks of the organic layer by X-cutting made corrosion spots of submicron size after a 2-day wet-and-dry corrosion test, which were monitored by SANS. [ABSTRACT FROM AUTHOR]

Abstract: An increasing human population requires a secure food supply and a cost effective, oral vaccine delivery system for livestock would help facilitate this end. Recombinant antigen adsorbed onto silica beads and coated with myristic acid, was released (∼15% (w/v)) over 24h at pH 8.8. At pH 2, the myristic acid acted as an enteric coating, protecting the antigen from a variety of proteases. The antigen adsorbed onto silica particles, coated in myristic acid had a conserved secondary structure (measured by circular dichroism (CD) spectroscopy) following its pH-triggered release. Small angle neutron scattering (SANS) was used to measure the thickness of the adsorbed antigen, finding that its adsorbed conformation was slightly greater than its solution radius of gyration, i.e. 120–160Å. The addition of myristic acid led to a further increase in particle size, with scattering data consistent with an acid thickness slightly greater than a monolayer of fully extended alkyl chains and a degree of hydration of around 50%. Whilst adsorbed onto the silica and coated in myristic acid, the protein was stable over 14 days at 42°C, indicating a reduced need for cold chain storage. These data indicate that further investigation is warranted into the development of this technology. [Copyright &y& Elsevier]

We report the synthesis and design of aqueous monodisperse copolymer latexes by miniemulsion polymerization and their application as binders in pigment printing and ink-jet printing of cotton fabrics. For that purpose, miniemulsion radical polymerization was carried out with a high content of the soft butyl acrylate (BA) and a low content of the hard methyl methacrylate (MMA) in the presence of hexadecane as osmotic costabilizer. The addition of small amounts of functional monomers such as methacrylic acid MAA and N-methylol acrylamide NMA to some miniemulsion recipes allowed to impart cross-linking sites and functionality to the copolymer chains. Dynamic light scattering (DLS), small angle neutron scattering (SANS), and transmission electron microscopy (TEM) showed that the particle size diameter and size distributions could be controlled in the range of 50 to 400 nm by the amount of SDS surfactant, while the presence of a costabilizer such as hexadecane determines the particle size and, to a lesser extent, the polydispersity of the obtained miniemulsion latex dispersions. The glass transition temperature of the different miniemulsion latexes ranged between −14 and −33 °C, depending on the monomer composition. Selected samples of these nanolatexes were then employed in textile printing. The miniemulsion binders with their uniform shape and smaller size have technological advantages over conventional processes for the pigment and ink-jet printing and yielded better printing properties in terms of softness, fastness, and color strength of the printed fabric. Accordingly, by optimized use of the miniemulsion method, one is not only able to control the particle size but also to improve the properties of these latexes for textile applications. [ABSTRACT FROM AUTHOR]

Highlights: [•] Effect of four divalent counterions on the self-assembly of surfactin is reported. [•] Ni2+ exhibits the highest degree of counterion association. [•] Surfactin forms spherical, cylindrical shaped vesicles and large aggregates. [•] Counterions with the highest affinity provoke drastic changes in the self-assembly. [Copyright &y& Elsevier]

Understanding the structure-property relationships of drug delivery system (DDS) components is critical for their development and the prediction of bodily performance. This study investigates the effects of introducing polyethylene oxide (PEO) homopolymers, over a wide range of molecular weights, into Pluronic injectable smart hydrogel formulations. These smart DDSs promise to enhance patient compliance, reduce adverse effects and dosing frequency. Pharmaceutically, Pluronic systems are attractive due to their unique sol-gel phase transition in the body, biocompatibility, safety and ease of injectability as solutions before transforming into gel matrices at body temperature. This paper presents a systematic and comprehensive evaluation of gelation and the interplay of microscopic and macroscopic properties under both equilibrium and non-equilibrium conditions in controlled environments, as measured by rheology in conjunction with time-resolved Small Angle Neutron Scattering (SANS). The non-equilibrium conditions investigated in this work offer a better understanding of the two polymeric systems' complex interactions affecting the matrix thermo-rheological behaviour and structure and therefore the future release of an active pharmaceutical ingredient from the injectable DDS. [Display omitted] [ABSTRACT FROM AUTHOR]

Highlights: [•] The phase diagram of mixed commercial ethoxylated surfactants was developed. [•] Considered surfactants are widely used in homecare detergent formulations. [•] The LLC structures were identified by POM, SAXS and SANS. [•] Effects of hydrophobic and hydrophilic chains polydispersity were highlighted. [•] Relation of supramolecular structures with segregation phenomena was studied. [Copyright &y& Elsevier]

Highlights: [•] Soft cyclotetramerization of carboranyl(alkylthio)maleonitriles affords carboranyl(alkylthio)porphyrazines. [•] Carboranyl(alkylthio)porphyrazines/liposome adducts are structurally and chemically stable. [•] Carboranyl(alkylthio)porphyrazines/liposome adducts introduce large B amounts into cancerous cells. [Copyright &y& Elsevier]

Abstract: Presence of sialic acid distinguishes gangliosides from other glycosphingolipids, helps maintain membrane structure and organization as well as acts as anchors for lectins, toxins and pathogens. The number and position of the sialic acid residues on gangliosides appear to influence the binding affinity and specificity of gangliosides. We have investigated the dependence of bicellar properties on sialic acids using monosialo1 (GM1), disialo1b (GD1b) and trisialo1a (GT1a) gangliosides incorporated in phospholipid bicelles. TEM, AFM and DLS show that increasing numbers of sialic acid moieties per ganglioside results in an increase in bicelle size. DPH fluorescence anisotropy results suggest that with incorporation of gangliosides in bicelles the orientational order of the hydrocarbon chains increases. Fluorescence anisotropy was used to explore the effect of gangliosides on lateral phase separation in ganglioside enriched bicelles. GM1 and GT1a exhibited a low T m melting domain (DMPC rich) and a high T m melting domain (ganglioside rich). For GD1b containing bicelles, no significant phase separation was observed, suggesting a single homogeneous phase. Symmetric and antisymmetric stretching vibrational bands of methylene shift to a lower wave number, implying acyl chain order decreasing as GT1a≪GM1

The use and application of cryogenic storage for cooling purposes rapidly increasing. It's find their way to be apply in land, sea and space. The rise of usage of low temperature techniques is corresponding with the efficient usage of cryogenic liquids where the liquids boils at below ambient temperature. However, the designs of the cryogenic storage need to be optimize to ensure the efficiency of the system. In this paper, a cryostat for cooling of beryllium filters of a small-angle neutron scattering (SANS) instrument of TRIGA MARK II PUSPATI research reactor was investigated using computational fluid dynamics (CFD) package FLUENT 6.2. The simulation was focus on the cooling profile or temperature distribution of the beryllium filters via the thermal link from the cryogenic tank in the cryostat. The temperature simulation data are then compared against the experimental results. From the analysis the temperature profile shows agreement on the decrease of temperature compared to the experimental result. [ABSTRACT FROM AUTHOR]

Abstract: Nanocomposites of polyaniline nanofibers and polyimide were fabricated and studied using small angle neutron scattering (SANS). The immiscible nature of the conformationally dissimilar polyaniline nanofiber and polyimide host is established by a series of experiments involving neutron scattering. Based on these techniques, we conclude that the crystal structure of the polyimides is not disrupted, and that there is no mixing between the two components on a molecular level. The morphology of the conducting salt component was analyzed by SANS data and was treated by two common models: Debye–Bueche (D–B) and inverse power law (IPL). Due to deviations in the linear curve fitting over a large scattering range, neither the D-B nor the IPL model could be used to characterize the size and shape of all PANI-0.5-CSA (polyaniline camphor sulfonic acid doped polymer)/polyimide blend systems. At 1 and 2% concentration, the D–B model suggested salt domains between 20 and 70Å with fractal geometries implied by the IPL model. As salt concentrations increased to 5%, the structures were observed to change, but there is no simple structural model that provides a suitable basis for comparison. [Copyright &y& Elsevier]