Hasil untuk "Chemistry"

W. Martin, J. Baross, D. Kelley et al.

A. Goldstein, I. Galbally

P. Griffiths

M. Thompson, Stephen L. R. Ellison, R. Wood

Abstract Method validation is one of the measures universally recognized as a necessary part of a comprehensive system of quality assurance in analytical chemistry. In the past, ISO, IUPAC, and AOAC International have cooperated to produce agreed protocols or guidelines on the "Design, conduct and interpretation of method performance studies" [1], on the "Proficiency testing of (chemical) analytical laboratories" [2], on "Internal quality control in analytical chemistry laboratories" [3], and on "The use of recovery information in analytical measurement" [4]. The Working Group that produced these protocols/guidelines has now been mandated by IUPAC to prepare guidelines on the single-laboratory validation of methods of analysis. These guidelines provide minimum recommendations on procedures that should be employed to ensure adequate validation of analytical methods. A draft of the guidelines has been discussed at an International Symposium on the Harmonization of Quality Assurance Systems in Chemical Laboratory, the proceedings from which have been published by the UK Royal Society of Chemistry.

R. Mancini, M. Hunt

B. Vallée, K. Falchuk

L. J. Bellamy

R. Chambers

B. Webb, A. H. Johnson

Jingyang Wu, Jinniu Miao, Yue Wang et al.

The stability of perovskite materials in humid conditions significantly hinders their practical deployment. This study employed ab initio molecular dynamics (AIMD) simulations based on the Car–Parrinello approach to elucidate the adsorption mechanisms within two systems: CH₃NH₃PbI₃-15O₂-2H₂O and CH₃NH₃PbI₃-15O₂-5H₂O. The findings indicate that in the system with a higher water content (5H₂O), the degradation of the perovskite skeleton is more severe. Additionally, the adsorption energy of oxygen molecules significantly increases, along with more pronounced charge transfer between the oxygen and the perovskite material. The study also reveals that although water molecules contribute to the damage of the perovskite skeleton, oxygen molecules are the primary culprits. These insights not only clarify the specific impacts of various components in a mixed-gas environment on perovskite stability but also provide an essential theoretical basis for future modifications and optimizations of perovskite materials.

Yibo Wang, Md Sazzad Hossain, Tianlin Li et al.

Abstract Two-dimensional ferroelectric materials like NbOI2 have garnered significant interest, yet their temporal response and synergetic interaction with light remain underexplored. Previous studies on the polarization of oxide ferroelectrics have relied on time-resolved optical second harmonic generation or ultrafast X-ray scattering. Here, we probe the laser-induced polarization dynamics of NbOI2 nanocrystals using ultrafast transmission electron diffraction and deflectometry. The deflection of the electron pulses is directly sensitive to the changes in the polarization, while the diffraction signal captures the structural evolution. Excited with a UV laser pulse, the polarization of NbOI2 is initially suppressed for two picoseconds, then it recovers and overshoots, leading to a transiently enhanced polarization persisting for over 200 ps. This recovery coincides with coherent acoustic phonon generation, triggering a piezoresponse in the NbOI2 nanocrystals. Our results offer a new method for sensing the ferroelectric order parameter on femtosecond time scales.

Owusu-Gyimah Victor, Phanuel Yao Klogo, Francis Gbefo

A study in southwestern Ghana compared the effects of organic and inorganic additives on P availability and related factors in two acidic soils, Ankasa and Abenia. Different amounts of P as KH2PO4 were applied: 0.067 g kg-1 for Abenia and 0.041 g kg-1 for Ankasa. Soil samples were treated with cow dung, Chromolaena odorata, and poultry droppings for six weeks to increase standard P requirement and neutralize exchangeable Aluminum. Data analysis was performed using GenStat (version 14). An analysis of variance (ANOVA) was conducted for the soil amendments, followed by Tukey’s comparison test at a 5% significance level to identify significant differences among the soil amendments. The result showed that higher rates of organic amendments significantly increased pH, available P (Bray 1 and NaHCO3-P), NaOH-P, and reduced exchangeable Al concentration. Poultry droppings and cow dung impact notably improved soil quality. At the same time, CaCO3 had similar effects on soil pH. However, it did not significantly affect P availability or NaOH-extractable P. CaSO4 and CaCO3 had minimal impact on phosphorus distribution, suggesting that altering pH or exchangeable Al does not necessarily change P fractions. Poultry droppings, rich in P, could be a potential alternative to lime in enhancing P availability and reducing soil acidity.

Fan Zhang, Xue-de Wang, Ke Li et al.

This study developed a novel and green method to produce fragrant sesame oil using microwaves and subcritical extraction (SBE). Sesame seeds were microwaved at 540 W for 0–9 min before subcritical propane extraction at 40 °C and 0.5 MPa. SBE caused less deformation to the cellular microstructure of sesame cotyledons while dramatically improving oil yield (96.7–97.1 %) compared to screw processing (SP) (53.1–58.6 %). SBE improved extraction rates for γ-tocopherol (381.1–454.9 μg/g) and sesame lignans (917.9–970.4 mg/100 g) in sesame oil compared to SP (360.1–443.8 μg/g and 872.8–916.8 mg/100 g, respectively). Microwaves generated aroma-active heterocyclics and phenolics faster than hot-air roasting in sesame oil with a better sensory profile. SBE had a higher extraction rate for aroma-active terpenes, alcohols, and esters while reducing the concentrations of carcinogenic PAHs and HCAs in sesame oil. The novel combination process of microwaves and subcritical extraction is promising in producing fragrant sesame oil with superior qualities.

Seung Ju Kim, Hyeon-Ji Lee, Chul-Ho Lee et al.

Abstract Neuromorphic hardware enables energy-efficient computing, which is essential for a sustainable system. Recently, significant progress has been reported in neuromorphic hardware based on two-dimensional materials. However, traditional planar-integrated architectures still suffer from high energy consumption. This review systematically explores recent advances in the three-dimensional integration of two-dimensional material-based neuromorphic hardware to address these challenges. The materials, process, device physics, array, and integration levels are discussed, highlighting challenges and perspectives.

Yulia M. T. A. Putri, Muhammad I. Syauqi, Isnaini Rahmawati et al.

Abstract The growing demand for sustainable energy sources has spurred significant studies to optimize the potency of fuel cell technology. Direct urea fuel cell (DUFC) has gained attention due to their energy density, eco‐friendliness, and potential applications in power generation using urea from various sources, including wastewater and urine. Efficient electrocatalysts are pivotal in DUFCs, and nickel‐based catalysts, particularly in the form of NiOOH, have demonstrated cost effectiveness, excellent stability in alkaline media, and good activity for urea oxidation reaction. However, low‐density and durability are still the major limitation in the overall DUFC performance. This review provides a comprehensive analysis of the latest development in Ni‐based catalysts, covering synthesis methods, factors influencing the catalytic activity as well as their implications for DUFC performance durability and commercial viability. In addition, another important factor including the use of different oxidant and electrolyte medium is also elaborated. Based on this review, 2D‐3D Ni‐based materials with the addition of other metals and the use of non‐oxide nickel binary compound are predicted to be the future evolution of the effective nickel‐based catalysts.

Ana Torres, Isabel F. Almeida, Rita Oliveira

Compounding is currently an integral part of pharmacy practice, and it is essential to the provision of healthcare. Compounding is an important therapeutic option in all areas of medicine, with relevance to dermatological treatments. Compounding topical medicines can be time-consuming and requires specialized equipment. In this regard, the use of proprietary topical liquid and semisolid vehicles/bases can be a good alternative and a more sustainable approach. This review provides an overview of existing proprietary vehicles/bases, summarizing their properties and applications and identifying existing commercial and information gaps. Creams emerge as the foremost topical base, followed by gels and ointments. Besides acting locally on the skin, almost a third of these proprietary bases/vehicles are also suitable for the transdermal application of APIs. Information regarding composition and compatibilities/incompatibilities with APIs is not always provided by the manufacturer, constraining a complete analysis of all proprietary topical bases/vehicles considered. The collection and organization of this information are important not only for pharmacy practice and physician prescription, helping to select the best vehicles/bases, but also for the industry to identify opportunities for innovation.

S. Arai

Péter Nagy

Luis F. Bobadilla, Lola Azancot, Ligia A. Luque-Álvarez et al.

Nowadays, global climate change is likely the most compelling problem mankind is facing. In this scenario, decarbonisation of the chemical industry is one of the global challenges that the scientific community needs to address in the immediate future. Catalysis and catalytic processes are called to play a decisive role in the transition to a more sustainable and low-carbon future. This critical review analyses the unique advantages of structured reactors (isothermicity, a wide range of residence times availability, complex geometries) with the multifunctional design of efficient catalysts to synthesise chemicals using CO₂ and renewable H₂ in a Power-to-X (PTX) strategy. Fine-chemistry synthetic methods and advanced in situ/operando techniques are essential to elucidate the changes of the catalysts during the studied reaction, thus gathering fundamental information about the active species and reaction mechanisms. Such information becomes crucial to refine the catalyst’s formulation and boost the reaction’s performance. On the other hand, reactors architecture allows flow pattern and temperature control, the management of strong thermal effects and the incorporation of specifically designed materials as catalytically active phases are expected to significantly contribute to the advance in the valorisation of CO₂ in the form of high added-value products. From a general perspective, this paper aims to update the state of the art in Carbon Capture and Utilisation (CCU) and PTX concepts with emphasis on processes involving the transformation of CO₂ into targeted fuels and platform chemicals, combining innovation from the point of view of both structured reactor design and multifunctional catalysts development.

Manuel Aureliano, Manuel Aureliano, Scott G. Mitchell et al.