Glass is a matter of time
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NMR study of a gel layer formed on an irradiated Na-aluminoborosilicate glass during aqueous alteration
Simplified borosilicate glass powders were irradiated by 952 MeV 136Xe ions and then altered in a solution at a high S/V ratio at pH 9 and 90 °C for 33 days. Compared to the alteration of a non-irradiated sample, the irradiated sample altered 3–5 times more. Overall, both the gels had a similar structure as indicated by 29Si, 27Al, 23Na, and 17O NMR experiments. Nevertheless, according to 11B and 1H NMR experiments, differences were observed in the quantity and speciation of B retained in the gels. The results suggest that the glass alteration mechanisms responsible for passivation are not changed because of the irradiation-induced structural damages. However, the alteration kinetics, gel morphology related to porosity, and the degree of maturation are different. It seems that the gel formed on irradiated glass matures faster and retains B, which in turn influences the glass dissolution rate.
Chinese glass ornaments from the port site of Shuo Gate, Zhejiang, China, 10th–13th Century CE
Ancient China is often regarded as the country of clothes and hair ornaments due to numerous archaeological finds. The tradition to study dress and hair decorations reflects their practical use, social status, and aesthetic spirit of ancient Chinese people. Hairpins, used for stabilizing the long hair of both men and women, are one of the most common hair accessories in the history of China. This paper is the first to specifically concentrate on glass hairpins rather than other glass ornaments such as beads and bangles. The finds were excavated in 2022 from an ancient port site named as Shuo Gate. The site is located in the north of Wenzhou, Zhejiang Province, a coastal city in southern China along the maritime Silk Road. Five representative samples in different colours and levels of opacification were selected for scientific analysis. LA-ICP-MS analysis was applied on the glass material to obtain compositional results and integral characteristics of each sample. Furthermore, non-invasive methods such as micro-CT and Raman spectroscopy were employed to determine the inner structure of this special type of glass ornament and to explore the possible manufacturing techniques used between the 10th and 13th centuries CE. Based on the compositions of the major and minor elements, they were divided into two distinct types: K2O-PbO-SiO2 and K2O-CaO-SiO2 glass. The relationships between the glass finds and the site were also discussed for their possible provenances and commodity attributes. Combined with other published reports, the study contributes to a deeper understanding of origin, distribution and communication with the world along the maritime Silk Road in terms of Chinese glass.
Genome-wide analysis identifies novel shared loci between depression and white matter microstructure
Depression, a complex and heritable psychiatric disorder, is associated with alterations in white matter microstructure, yet their shared genetic basis remains largely unclear. Utilizing the largest available genome-wide association study (GWAS) datasets for depression (N = 674,452) and white matter microstructure (N = 33,224), assessed through diffusion tensor imaging metrics such as fractional anisotropy (FA) and mean diffusivity (MD), we employed linkage disequilibrium score regression method to estimate global genetic correlations, local analysis of [co]variant association approach to pinpoint genomic regions with local genetic correlations, and conjunctional false discovery rate analysis to identify shared variants. Our findings revealed that depression showed significant local genetic correlations with FA in 37 genomic regions and with MD in 59 regions, while global genetic correlations were weak. Variant-level analysis identified 78 distinct loci jointly associated with depression (25 novel loci) and FA (35 novel loci), and 41 distinct loci associated with depression (17 novel loci) and MD (25 novel loci). Further analyses showed that these shared loci exhibited both concordant and discordant effect directions between depression and white matter traits, as well as distinct yet overlapping hemispheric patterns in their genetic architecture. Enrichment analysis of these shared loci implicated biological processes related to metabolism and regulation. This study provides evidence of a mixed-direction shared genetic architecture between depression and white matter microstructure. The identification of specific loci and pathways offers potential insights for developing targeted interventions to improve white matter integrity and alleviate depressive symptoms.
The effectiveness of TRIS and ammonium buffers in glass dissolution studies: a comparative analysis
Selecting appropriate buffers is crucial for evaluating the chemical durability of glass under controlled conditions such as in the EPA 1313 test designed to measure elemental release as a function of pH. The efficacy of two alkali-metal free buffers, TRIS (NH2C(CH2OH)3) and ammonium chloride—ammonia (NH3/NH4Cl), was investigated during EPA 1313 testing of a simulated Hanford low-activity waste borosilicate glass in the alkaline regime (pH 8.5–10.5) at varying temperatures (RT, 40 °C, and 60 °C). While both buffers maintained the desired pH at room temperature, and up to 40 °C, the effectiveness of TRIS decreased at elevated temperatures, particularly at pH 10.5. Although 11B NMR showed evidence of TRIS-B complexation, its effect on the rate of elemental release was found to be negligible under the test conditions. With ammonium buffer, the release of alkali cations was slightly elevated when compared to the same conditions with TRIS at early time points.
Direct observation of the topological pruning in silica glass network; the key for realizing extreme transparency
The optical transparency of silica glass significantly improves when subjected to compression at its melting temperature. Using a rare hydrostatic iso-pressure apparatus capable of reaching 0.98 GPa at 1800 °C with Ar gas as the pressure medium, we obtained centimeter-sized glass samples, allowing us to measure various properties. Both the density and refractive index increased with pressure, while the refractive index dispersion decreased monotonically. However, Rayleigh scattering intensity, and small ring structures show a minimum around 0.8 GPa. High-energy X-ray scattering analysis indicates that the short-range structure, around 4 Å, governs the monotonic trends in the averaged physical properties, such as density and refractive index. In contrast, non-monotonic changes are observed with the disappearance of intermediate-range order at around 8 Å. This simplification of structural ordering is crucial for achieving extreme transparency in silica glass. The effect of suppression of the 8 Å order is well explained by the predicted topological pruning phenomenon, where large voids and small unstable ring structures vanish, leading to the minimal light scattering under high pressure. Our experimental findings also reveal that the optimal pressure for achieving this transparency is much lower than previously predicted, which makes the process more feasible for mass-production applications.
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