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An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Recent measurement studies have found that urban natural gas (NG) emissions are 3.9× larger than bottom-up inventory estimates, on average, across various North American cities.1 Several studies have proposed that post-meter emissions may be a substantial missing source in urban methane (CH4) estimates, but the role of diffuse residential and commercial NG consumption in overall emissions remains uncertain. Long-term, continuous eddy covariance flux measurements can help clarify possible post-meter contributions by providing localized, high-resolution observations of cumulative emissions. Here we present nearly 3 years of CH4 flux measurements collected between July, 2022 and April, 2025 from a 42 m tall stationary tower located in downtown Berkeley, California, USA. Methane source types were characterized using contemporaneous ethane and δ13CH4 measurements, and spatially resolved population, building, and land use datasets were used to determine possible post-meter emissions drivers. Average annual CH4 fluxes in Berkeley were 152 nmol m-2 s-1 [95%: 150,155] and were primarily attributed to natural gas. Fluxes were dominated by a persistent spatial gradient wherein higher fluxes were associated with increased commercial building space and lower population density in the downtown core, with estimated average annual fluxes ranging from 85 nmol m-2 s-1 [95%: 82.8, 88.3] in residential areas to 218 nmol m-2 s-1 [95%: 214, 223] downtown. Flux diurnal trends were distinct between different seasons and dominant land uses, but no significant weekday-weekend differences were observed. Residential areas had lower diurnal variation and higher springtime fluxes—exhibiting no positive correlation with NG consumption. In denser commercial areas, CH4 fluxes were significantly lower during warmer months, and monthly emissions were positively correlated with NG consumption at rates of 0.21% and 0.23%. Overall fluxes were 5× larger than the highest inventory estimates and were elevated relative to urban eddy covariance studies in similarly sized European and Asian cities. Our results emphasize how eddy covariance studies can help identify and track the drivers of larger urban CH4 emissions trends and the importance of evaluating these trends across different spatial scales.[1] Vollrath, et al. (2025) Environ. Res. Lett.
Silk fabric reinforced epoxy composites (SFRPs) were prepared by simple hot-press and vacuum treatment, to achieve a maximum reinforcement fraction of 70vol.%-silk. Mechanical behaviour, specifically tensile, flexural, interlaminar shear, impact, dynamic and thermal properties of the SFRPs, was investigated. It was shown that reinforcement by silk fabric can greatly enhance the mechanical performance of SFRPs. In particular, the tensile modulus and breaking energy of 70vol.%-silk SFRP were 145% and 467% higher than the pristine epoxy resin. Moreover, the flexural modulus, ultimate strength and breaking energy were also markedly increased for SFRPs. The flexural strength increased linearly with increasing silk volume fraction from 30 to 60vol.% but diminished slightly at 70vol.%. Additionally, interlaminar shear results showed that the silk and the matrix epoxy resin had better adhesion properties than plain woven flax fibre. Of most significance is that the impact strength reached a maximum of ~71kJ m−2 for the 60vol.%-silk SFRP, which demonstrates the potential of silk reinforcements in impact-resistant composites for applications such as wind turbine blades. Our study may shed light on improving the strength and toughness of engineering composites by incorporating high volume fractions of natural fibres.
The concept of a natural tiling for a periodic net is introduced and used to derive a transitivity associated with the structure. It is accordingly shown that the transitivity provides a useful method of classifying polyhedra and nets. For design of materials to serve as targets for synthesis, structures with one kind of edge (edge transitive) are particularly important. Edge-transitive polyhedra, layers and 3-periodic nets are then described. Some other nets of special importance in crystal chemistry are also identified.
Throughout the 1990s health care providers were interested in developing organized delivery systems. However, industry observers have increasingly questioned the sense of these efforts. Using an established taxonomy of health networks and systems, we examined whether there was a nationwide trend away from the vertical and horizontal arrangements that serve as the backbone to organized delivery systems. Studying 1994-1998, we found that both health networks and systems became less centralized in their hospital services, physician arrangements, and insurance product development. We did not find a general pathway to disintegration but instead found considerable experimentation in organizational form.
ABSTRACT The thiosulfate reductase gene ( phsABC ) from Salmonella enterica serovar Typhimurium was expressed in Escherichia coli to overproduce hydrogen sulfide from thiosulfate for heavy metal removal (or precipitation). A 5.1-kb DNA fragment containing phsABC was inserted into the pMB1-based, high-copy, isopropyl-β- d -thiogalactopyranoside-inducible expression vector pTrc99A and the RK2-based, medium-copy, m -toluate-inducible expression vector pJB866, resulting in plasmids pSB74 and pSB77. A 3.7-kb DNA fragment, excluding putative promoter and regulatory regions, was inserted into the same vectors, making plasmids pSB103 and pSB107. E. coli DH5α strains harboring the phsABC constructs showed higher thiosulfate reductase activity and produced significantly more sulfide than the control strains under both aerobic and anaerobic conditions. Among the four phsABC constructs, E. coli DH5α (pSB74) produced thiosulfate reductase at the highest level and removed the most cadmium from solution under anaerobic conditions: 98% of all concentrations up to 150 μM and 91% of 200 μM. In contrast, a negative control did not produce any measurable sulfide and removed very little cadmium from solution. Energy-dispersive X-ray spectroscopy revealed that the metal removed from solution precipitated as a complex of cadmium and sulfur, most likely cadmium sulfide.
