A Remote Raman System and Its Applications for Planetary Material Studies

Design and development of a stand-off Raman brassboard (SDU-RRS) for the spectroscopic study of planetary materials

Raman spectroscopy has emerged as a crucial mineral analysis technique in planetary surface exploration missions. Nonetheless, the inherently low Raman scattering efficiency of planetary silicate materials makes it challenging to extract enough Raman information. Theoretical and experimental studies of the remote Raman scattering properties of planetary materials are also urgent requirements for future lunar and planetary explorations. Here, Shandong University Remote Raman Spectrometer (SDU-RRS) was developed to demonstrate the feasibility of lunar remote Raman technology and conduct preliminary research on remote Raman scattering properties. SDU-RRS utilizes a pulsed 532 nm laser, a non-focal Cassegrain telescope, a volume phase holographic grating, an intensified charge-coupled device, and the time-gating technique to detect weak-signal silicate minerals. The spectral resolution obtained with atomic emission lamps was <4.91 cm-1, and the wavelength accuracy was <1 cm-1, across the spectral range of 241-2430 cm-1. SDU-RRS can detect natural augite within a feldspar-olivine-augite matrix at a concentration of 20 % at ∼1 m under ambient lighting conditions. A series of experiments were conducted to evaluate the influence of measurement conditions and physical matrix effects on acquired Raman signals, either qualitatively or quantitatively, on geological materials. The study indicates that the transmission of Raman-scattered light conforms to Lambert's cosine law, and a linear correlation exists between Raman intensity and laser power. The study also evaluated the impact of grain size, surface roughness, porosity, and shadow-hiding effects. Reducing grain size decreases Raman intensity and broadens Raman spectra. These characteristics are essential for achieving definitive mineralogical information from granular materials by remote Raman spectroscopy in lunar and planetary explorations.

Rethinking primary particulate matter: Integrating filterable and condensable particulate matter in measurement and analysis

The current definition of primary particulate matter (PM) encompasses filterable PM (FPM) and condensable PM (CPM), which are evaluated using two distinct conventional measurement methods: cooling and dilution. While the cooling method exclusively considers the homogenous formation of CPM, the dilution method, closer to real-world conditions, neglects FPM characterization. To overcome this limitation, we propose a doubled-dilution system that enables the parallel characterization of both FPM and primary PM without diverting FPM from the CPM formation pathway. The doubled-dilution system has been investigated from a laboratory scale to a full-scale coal-fired power plant to facilitate simultaneous, real-time measurements of primary PM and FPM size distributions. Moreover, the formation rates of homogeneous and heterogeneous nucleation were compared. The evolution of the primary PM size revealed a bimodal distribution, and the filter-based mass concentration results demonstrated a pronounced preference for heterogeneous reactions (17.6 times higher than homogeneous nucleation). In particular, primary PM emissions were underestimated by up to 65.3 % when only homogeneous CPM formation was considered, underscoring the importance of including FPM during primary PM measurements. Considering these results, we advocate adopting the term "primary PM" over "CPM."

Indicator Minerals, Pathfinder Elements, and Portable Analytical Instruments in Mineral Exploration Studies

Until recently, the classic approach to mineral exploration studies was to bring the field samples/drill cores collected during field studies to the laboratory, followed by laborious analysis procedures to generate the analytical data. This is very expensive, time-consuming, and difficult for exploring vast areas. However, rapid technological advances in field-portable analytical instruments, such as portable visible and near-infrared spectrophotometers, gamma-ray spectrometer, pXRF, pXRD, pLIBS, and µRaman spectrometer, have changed this scenario completely and increased their on-site applications in mineral exploration studies. LED fluorimeter is a potential portable tool in the hydrogeochemical prospecting studies of uranium. These instruments are currently providing direct, rapid, on-site, real-time, non-destructive, cost-effective identification, and determination of target elements, indicator minerals and pathfinder elements in rock, ore, soil, sediment, and water samples. These portable analytical instruments are currently helping to obtain accurate chemical and mineralogical information directly in the field with minimal or no sample preparation and providing decision-making support during fieldwork, as well as during drilling operations in several successful mineral exploration programs. In this article, the developments in these portable devices, and their contributions in the platinum group elements (PGE), rare earth elements (REE), gold, base metals, and lithium exploration studies both on land and on the ocean bed, have been summarized with examples.

The Study of Protein-Cyclitol Interactions

Investigation of interactions between the target protein molecule and ligand allows for an understanding of the nature of the molecular recognition, functions, and biological activity of protein-ligand complexation. In the present work, non-specific interactions between a model protein (Bovine Serum Albumin) and four cyclitols were investigated. D-sorbitol and adonitol represent the group of linear-structure cyclitols, while shikimic acid and D-(-)-quinic acid have cyclic-structure molecules. Various analytical methods, including chromatographic analysis (HPLC-MS/MS), electrophoretic analysis (SDS-PAGE), spectroscopic analysis (spectrofluorimetry, Fourier transform infrared spectroscopy, and Raman spectroscopy), and isothermal titration calorimetry (ITC), were applied for the description of protein-cyclitol interactions. Additionally, computational calculations were performed to predict the possible binding places. Kinetic studies allowed us to clarify interaction mechanisms that may take place during BSA and cyclitol interaction. The results allow us, among other things, to evaluate the impact of the cyclitol's structure on the character of its interactions with the protein.