Structure, optical and luminescence properties of anhydrous samarium iodate Sm3(IO3)9(HIO3)4.

A new non-centrosymmetric iodate crystal Sm3(IO3)9(HIO3)4 has been successfully synthesized by a hydrothermal method. The crystal structure is a three-dimensional network with samarium polyhedra linked by iodate groups. It shows a moderate second harmonic generation response of 1.1 × KH2PO4 (KDP). The strongest emission in its luminescence spectrum is located at 600 nm under 403 nm excitation. Hence, Sm3(IO3)9(HIO3)4 is a potential orange laser material.

Spatial patterns and influencing factors of sewage treatment plants in the Guangdong-Hong Kong-Macau Greater Bay Area, China.

Over the past few years the discharge of waste and sewage in the Guangdong-Hong Kong-Macau Greater Bay Area (GHMB) of China has increased, exerting a great amount of pressure on ecological protection. In this study, we focus on achieving a balanced spatial layout of sewage treatment plants in order to reveal the regional differences and spatial patterns of sewage treatment plants in the GHMB and identify the key factors influencing the spatial patterns. In particular, we employ POI (point of interest) geographical data to evaluate the spatial patterns and agglomeration status of sewage treatment plants in the GHMB using Exploratory Spatial Data Analysis (ESDA). We then explore the principle influencing factors of the determined spatial patterns using the geographical weighted regression model (GWR). Results demonstrate that: (1) the absolute number of sewage treatment plants is highest in the central and western regions, while the per capita of sewage treatment plants is clearly clustered in the northwest and southwest regions; (2) the absolute number of sewage treatment plants exhibits larger spatial dissimilarity than that of the per capita values, with High-High cluster types principally distributed in the conjunction areas of Jiangmen, Foshan and Zhaoqing in western GHMB and Low-Low clusters in the western Pearl River Delta (PRD) estuary; and (3) the key influencing factors are identified as GDP per capita, the output value of the primary and secondary industries and industrial water consumption. Regions with high regression coefficient fluctuations of the four influencing factors are centralized within the PRD estuary and adjacent regions. Policy recommendations including optimizing the sewage treatment plant layout, enhancing the service capacity potential of the existing sewage treatment plants and upgrading the industrial structure are proposed to promote a spatial equilibrium configuration of sewage treatment plants in the GHMB.

BaZnBe2(BO3)2F2: a novel zinc-beryllium borate with SBBO-type structure overcoming the polymorphism problem.

A novel zinc-beryllium borate BaZnBe2(BO3)2F2 was grown by a high-temperature flux method for the first time. It crystallizes in P3[combining macron] with the cell parameters of a = b = 4.5998, c = 7.7037 and Z = 1, which is different from BaMBe2(BO3)2F2 (M = Mg, Ca). Interestingly, when Zn replaces Mg and Ca in BaMgBe2(BO3)2F2 and BaCaBe2(BO3)2F2, the structure retains the same anionic group but the symmetry is lowered. The title compound contains a flexible net structure [Be3B3O6F3]∞ in the a-b plane with Ba and Zn atoms located in the interlayers accordingly, which overcomes the structural instability problems of SrBe2B2O7 (SBBO). The structure evolution from SBBO to BaZnBe2(BO3)2F2 was discussed. This work is of great significance to the discovery of new materials and the modification of existing materials.

Malodorous gases production from food wastes decomposition by indigenous microorganisms.

Volatile organic compounds (VOCs) produced during the degradation of food wastes may harm to the health of people and create annoyance in adjacent communities. In this work, the VOCs emitted from the decomposition food wastes including fruit, meat and vegetable, and their microbial communities were measured in three individual 57-L reactors for 61 days. Total of 232.8, 373.5, and 191.1 µg·kg-1·h-1 VOCs with oxygenated VOCs (57.6%), volatile organic sulfur compounds (VOSCs, 58.6%) and VOSCs (54.9%) as the main group were detected during fruit, meat and vegetable fermentation, respectively. 2-Butanone (55.1%) and ethyl acetate (13.8%) were the two most abundant VOCs from fruit wastes, while dimethyl sulfide (68.0 and 26.6%) and dimethyl disulfide (89.2 and 10.1%) were in vegetable and meat wastes. The predominant Firmicutes represented 93.0-99.9% of the bacterial communities of meat decomposition, while Firmicutes and Proteobacteria were the dominant phyla throughout the fruit digestion process. Proteobacteria (16.9%-83.6%) was the dominant phylum in vegetable wastes, followed by Bacteroidetes, Firmicutes, and Actinobacteria. Malodorous VOCs emissions were highly affected by microbial activity, the abundant Weissella, Leuconostoc and Enterobacteriaceae in vegetable wastes showed correlation with carbon disulfide and dimethyl sulfide, while dominant Peptococcus, Bacteroides, Lactobacillales and Peptoniphilus in meat wastes was related to dimethyl disulfide. Overall, significant differences and correlation between VOCs emission profiles and bacterial communities among different food wastes decomposition were observed. These data contribute to a more comprehensive understanding the relationship between microbial community dynamics and malodorous VOCs emission.

Na3B7O11F2: a new sodium-rich fluorooxoborate with a unique [B14O24F4] ring and a short ultraviolet absorption edge.

A new sodium-rich fluorooxoborate Na3B7O11F2 features a novel large [B14O24F4] ring formed by two corner-shared [B7O13F2] groups, each containing two [B3O7] anionic units linked by a [BO2F2] group. The band gap of the title compound calculated by using first-principles calculations is 7.69 eV (∼161 nm) and the birefringence refractive index is 0.083 at 193 nm. The results show that it is potentially an excellent deep-ultraviolet (DUV) birefringence crystal.

Deep-Ultraviolet Nonlinear Optical Crystal Cs2 Al2 (B3 O6 )2 O: A Benign Member of the Sr2 Be2 (BO3 )2 O Family with [Al2 (B3 O6 )2 O]2- Double Layers.

For the explorations of deep ultraviolet (DUV) nonlinear optical (NLO) borates, a type of important optoelectronic material, the (BO3 )3- group has been long regarded as the sole microscopic optically-active unit, and toxic Be-containing raw materials are frequently-adopted. Herein, a new DUV NLO crystal, Cs2 Al2 (B3 O6 )2 O (CABO), was designed and synthesized by simultaneously replacing the (BO3 )3- groups and Be2+ cations for (B3 O6 )3- units and Al3+ cations in Sr2 Be2 (BO3 )2 O, which possesses a favorable structure, through a chemical co-substitution approach. CABO exhibits a considerable DUV NLO capability because of the wide band gap and large birefringence originating from the [Al2 (B3 O6 )2 O]2- double layers. Remarkably, CABO melts congruently and does not contain the toxic beryllium, which is favorable for bulk-size crystal growth and practical applications.

Synthesis, crystal structure and optical properties of a new fluorocarbonate with an interesting sandwich-like structure.

A new fluorocarbonate, Na3Zn2(CO3)3F, was synthesized using a subcritical hydrothermal method. Na3Zn2(CO3)3F crystallizes in the space group C2/c with a sandwich-like framework in which the stacked [Zn(CO3)]∞ layers are connected with one another by bridging F atoms and [CO3] groups alternately. Interestingly, each Zn atom is surrounded by one F atom and four O atoms, forming a distorted [ZnO4F] trigonal bipyramid, which is observed for the first time in the carbonate system. Na3Zn2(CO3)3F has high transparency in a wide spectral region ranging from UV to mid IR with a short ultraviolet absorption edge (∼213 nm). First-principles calculations revealed that Na3Zn2(CO3)3F possesses a large birefringence (Δn = 0.11, λ = 589 nm), which is mainly contributed by the coplanar arrangement of [CO3] groups in the ab plane. Na3Zn2(CO3)3F might find applications as a UV birefringence crystal.