Evaluation of sample cell materials for aqueous solutions used in quasi-elastic neutron scattering measurements

For quasi-elastic neutron scattering (QENS) studies, sample cells made of pure or alloyed aluminium are frequently employed. Although the Al surface is protected by a passivating film, this film is not robust. Therefore, when the sample is an aqueous solution, chemical interactions between the Al surface and sample, promoted by corrosive entities such as chloride ions and certain conditions of pH, can compromise the integrity of the cell and interfere with the experiment. In this study, the corrosion susceptibilities of Al and its alloys were investigated by subjecting them to various treatments; the results were compared with those of other candidate materials with low chemical reactivity. This work showed that alloys with higher Al content and boehmite-coated surfaces are resistant to corrosion. In particular, for Al, the resistance is due to a reduction in the contact area achieved by reducing the surface roughness. QENS measurements of empty sample cells made of these materials revealed two results: (1) the profile of the cell fabricated with a copper-free Al alloy showed a minor dependence on the scattering vector magnitude Q and (2) reducing the real surface area of Al effectively suppresses its scattering intensity, while boehmite coating strengthens the scattering. Cells fabricated with Mo, Nb and single-crystal sapphire can be used as alternatives to Al because of their low scattering intensity and reduced dependence on Q.

A Study of Defects in InAs/GaSb Type-II Superlattices Using High-Resolution Reciprocal Space Mapping

In this paper, he study of defects in InAs/GaSb type-II superlattices using high-resolution an x-ray diffraction method as well as scanning (SEM) and transmission (TEM) electron microscopy is presented. The investigated superlattices had 200 (#SL200), 300 (#SL300), and 400 (#SL400) periods and were grown using molecular beam epitaxy. The growth conditions differed only in growth temperature, which was 370 °C for #SL400 and #SL200, and 390 °C for #SL300. A wings-like diffuse scattering was observed in reciprocal space maps of symmetrical (004) GaSb reflection. The micrometer-sized defect conglomerates comprised of stacking faults, and linear dislocations were revealed by the analysis of diffuse scattering intensity in combination with SEM and TEM imaging. The following defect-related parameters were obtained: (1) integrated diffuse scattering intensity of 0.1480 for #SL400, 0.1208 for #SL300, and 0.0882 for #SL200; (2) defect size: (2.5–3) μm × (2.5–3) μm –#SL400 and #SL200, (3.2–3.4) μm × (3.7–3.9) μm –#SL300; (3) defect diameter: ~1.84 μm –#SL400, ~2.45 μm –#SL300 and ~2.01 μm –#SL200; (4) defect density: 1.42 × 106 cm−2 –#SL400, 1.01 × 106 cm−2 –#SL300, 0.51 × 106 cm−2 –#SL200; (5) diameter of stacking faults: 0.14 μm and 0.13 μm for #SL400 and #SL200, 0.30 μm for #SL300.

Halal Critical Point Analysis of Bajakah Wood (Spatholobus littoralis Hassk.) Nano Particle as Anticancer Agent

Bajakah wood contains phenolic compounds, flavonoids, tannins, and saponins with anticancer activity. The discovery and development of new drugs require several stages. In the process, there are many possibilities of adding other substances to form new active substances or as solvents that allow drug preparations to be doubtful of halalness. Hence, it is necessary to analyze the critical point of halal ingredients. The purpose of this study was to determine the characteristics of the nanoparticles of bajakah wood (Spatholobus littoralis Hassk.) and to test the anticancer activity in several cancer cell cultures, as well as to analyze the critical point of halalness of the material. This research method is a composition test using chromatography and anticancer activity test using MTT. Analysis of the critical point of halal materials using hazard analysis critical control point (HACCP). The research was carried out at the Indonesian Engineering Nanotechnology Laboratory South Tangerang and the UGM Integrated Laboratory Sleman in July–December 2020. The results showed that bajakah wood nanoparticles contained pure water as a solvent, viscosity 0.08878 cP, scattering intensity 1.1059 cps, diameter 176.1+/−43.7 (nm). Cytotoxic test results showed IC50 against cell culture MCF7 1,063.28 (±114.98) g/mL, HepG2 53.34 (±0.35) g/mL, T47D 150.63 (±8.44) g/mL, WiDR 114.38 (±7.82) μg/mL, HTB 97.50 (±3.49) μg/mL, HeLa 182.95 (±36.22) μg/mL, and Vero 710.10 (±106.46) μg/mL. This study concludes that bajakah wood nanoparticles are not critical in terms of halal ingredients. At the same time, their anticancer activity is weak against breast cancer and uterine cervical cancer, medium categories against liver cancer and lung cancer, and is not toxic to normal cells. ANALISIS TITIK KRITIS KEHALALAN NANOPARTIKEL KAYU BAJAKAH (SPATHOLOBUS LITTORALIS HASSK.) SEBAGAI AGEN ANTIKANKERKayu bajakah mengandung senyawa fenolik, flavonoid, tanin, dan saponin yang memiliki aktivitas antikanker. Penemuan dan pengembangan obat baru memerlukan beberapa tahapan. Dalam prosesnya terdapat banyak kemungkinan penambahan zat lain untuk membentuk zat aktif baru atau sebagai pelarut yang memungkinkan sediaan obat diragukan kehalalannya. Oleh sebab itu, perlu dilakukan analisis titik kritis kehalalan bahan. Tujuan penelitian ini mengetahui karakteristik sediaan nanopartikel kayu bajakah (Spatholobus littoralis Hassk.) dan menguji aktivitas antikanker pada beberapa kultur sel kanker, serta menganalisis titik kritis kehalalan bahan. Metode penelitian ini adalah uji komposisi menggunakan kromatografi dan uji aktivitas antikanker menggunakan MTT. Analisis titik kritis kehalalan bahan menggunakan hazard analysis critical control point (HACCP). Penelitian dilakukan di Laboratorium Nanovasi Rekayasa Indonesia Tangerang Selatan dan Laboratorium Terpadu UGM Sleman pada Juli–Desember 2020. Hasil penelitian menunjukkan sediaan nanopartikel kayu bajakah mengandung pelarut air murni, viskositas 0,08878 cP, scattering intensity 1,1059 cps, berdiameter 176,1+/−43,7 (nm). Hasil uji sitotoksik menunjukkan IC50 terhadap kultur sel MCF7 1.063,28 (±114,98) μg/mL, HepG2 53,34 (±0,35) μg/mL, T47D 150,63 (±8,44) μg/mL, WiDR 114,38 (±7,82) μg/mL, HTB 97,50 (±3,49) μg/mL, HeLa 182,95 (±36,22) μg/mL, dan Vero 710,10 (±106,46) μg/mL. Kesimpulan penelitian ini bahwa nanopartikel kayu bajakah bersifat tidak kritis dalam kehalalan bahan. Selain itu, aktivitas antikankernya lemah terhadap kanker payudara dan kanker serviks uteri, sedang terhadap kanker hati dan kanker paru, serta tidak toksik pada sel normal.

Order-by-disorder from bond-dependent exchange and intensity signature of nodal quasiparticles in a honeycomb cobaltate

Recent theoretical proposals have argued that cobaltates with edge-sharing octahedral coordination can have significant bond-dependent exchange couplings thus offering a platform in 3d ions for such physics beyond the much-explored realisations in 4d and 5d materials. Here we present high-resolution inelastic neutron scattering data within the magnetically ordered phase of the stacked honeycomb magnet CoTiO3 revealing the presence of a finite energy gap and demonstrate that this implies the presence of bond-dependent anisotropic couplings. We also show through an extensive theoretical analysis that the gap further implies the existence of a quantum order-by-disorder mechanism that, in this material, crucially involves virtual crystal field fluctuations. Our data also provide an experimental observation of a universal winding of the scattering intensity in angular scans around linear band-touching points for both magnons and dispersive spin-orbit excitons, which is directly related to the non-trivial topology of the quasiparticle wavefunction in momentum space near nodal points.

Small Angle Scattering Intensity Measurement by an Improved Ocean Scheimpflug Lidar System

Quantification of the horizontal patterns of phytoplankton and the distribution of suspended particles across the sea’s surface has been greatly improved by traditional passive oceanic color remote sensing technology. Lidar technology has already been proven to be effective positive remote sensing technology to construct high-resolution bathymetry models. Lidar technology significantly improves our ability to model biogeochemical processes in the upper ocean and provides advanced concepts regarding the vertical distribution of suspended particles and oceanic optical properties. In this paper, we present a novel optical approach to measuring the scattering intensity and characteristics of suspended particles within small angles backwards and distinguish water medium with different attenuation coefficients by a laboratory demonstration of the ocean Scheimpflug lidar system. The approach allows the direct determination of the scattering intensity over a small angle at the backward direction (175.8°~178.8°) with an angular resolution of 0.38. Corrections for the effects of refraction at the air-glass-water interface were demonstrated. The data production (initial width and width attenuation rate of the laser beam) of the ocean Scheimpflug lidar system were utilized to distinguish water with different algae concentrations. Application for the measurement of backward scattering intensity and laser beam width were explored in distances up to several meters with spatial resolutions of millimeter precision.

Neutralization and Salt Effect on the Structure and Mechanical Properties of Polyacrylic Acid Gels under Equivolume Conditions

The effects of neutralization and salt on the structure and mechanical properties of polyacrylic acid (PAA) gels under equivolume conditions were investigated by small-angle X-ray scattering (SAXS) measurements and tensile tests. We attained the equivolume condition by immersing a piece of PAA gel sample in an ion reservoir containing linear PAA, NaOH, and NaCl at prescribed concentrations (post-ion-tuning). The volume fraction of the linear polymer was set to be the same as that of the gel so as to satisfy the iso-osmotic pressure at the reference state. Various types of reservoirs were prepared by adding NaOH and/or NaCl with different concentrations to the reference reservoir, followed by immersing a PAA gel piece. In the SAXS measurements, a scattering peak appeared, and the scattering intensity at q = 0 decreased by neutralization, while the addition of salt increased the scattering intensity. On the other hand, Young’s modulus measured with the tensile test decreased with neutralization; however, it scarcely changed with the addition of salt. The newly developed equivolume post-ion-tuning technique may serve as a new standard scheme to study polyelectrolyte gels.

Improve The Effective Resonance Light Scattering Of Three-Layered Plasmonic Au@Dielectric@Ag Bimetallic Nanoshells

The strong light scattering from SPR has received an extraordinary attention due to the useful applications in photodetectors, cell and biomedical imaging. However, the applications using light scattering require a high scattering cross-section along with low absorption losses near the resonance wavelength. In this paper, effective plasmonic scattering of three-layered Au-Ag bimetallic nanoshells with a dielectric separate layer has been studied using the quasi-static approximation of classical electrodynamics. Because of the surface plasmon resonance (SPR)-induced intense light absorption, the effective scattering intensity is much weaker than that of scattering cross section. However, the effective scattering intensity could be improved by tuning the geometric dimension and local dielectric environment of the nanostructure. It has been found that the greatest effective scattering takes place when the outer Ag nanoshell has a thick thickness or the dielectric separate layer has a small dielectric constant. The effective scattering also depends on the inner Au sphere radius and outer surrounding dielectric constant. Because of the mode transformation of the SPR, the effective scattering could also be greatly improved when the inner Au sphere has a very small or large size. However, the effective scattering intensity changes non-monotonously as the surrounding dielectric constant increases. The greatest effective scattering could be obtained when the surrounding dielectric constant has an intermediate value. This tunable effective plasmonic scattering of Au@Ag three-layered nanoshells presents a potential for design and fabrication of plasmonic optical nanodevice based on resonance light scattering.

Cavity Enhanced Multi-Channels Gases Raman Spectrometer

Raman spectroscopy has the advantages of multi-component detection, with a simple device and wide concentration ranges, and it has been applied in environmental monitoring and gas logging. However, its low sensitivity has limited its further applications. In fact, the Raman signal is not weak, but the utilization efficiency of the Raman signal is low, and most of the signal is wasted. Given this, in this paper we report a cavity-enhanced multi-channel gas Raman spectrometer with an eight-sided cuvette. First, we simulated the Raman scattering intensity at angles from 30 degrees to 150 degrees. The simulation results showed that the signal intensity at an angle of 45° is 1.4 times that observed at 90°. Based on the simulation results, we designed a three-channel sample cell for higher sensitivity. The results of these experiments showed that the sensitivity could be increased by adding all signal together, and the limit of detection (LOD) for CO2 was 75 ppm, which is better than that of each channel. This paper thus presents a new method to enhance the Raman signal, which can be used in field applications.