Search

Microalgae are considered to be a very promising class of raw material for carotenoid production. In this study, melatonin (MLT), a widely used plant growth regulator, was added to the autotrophic medium of Dunaliella bardawil to explore its effects on the growth and pigment accumulation of Dunaliella bardawil. The results showed that the induction of exogenous MLT alone was not beneficial to the growth and pigment accumulation of Dunaliella bardawil, and the higher the concentration, the more obvious the inhibitory effect on the algal cells. Therefore, a strategy to promote carotenoid accumulation in Dunaliella bardawil by combining exogenous MLT and light induction was carried out. Under 4500 LUX light intensity, the content of zeaxanthin was significantly increased under exogenous MLT induction. In the 200 μg/mL, 300 μg/mL, and 400 μg/mL MLT-treated groups, the zeaxanthin single-cell content in the 300 μg/mL-treated group was as high as 0.38 ng/mL (0.17 ng/mL in the control group), which was 1.24-fold higher compared to the control. Under 9500 LUX light intensity, all carotenoids showed an increasing trend in all experimental groups, except for zeaxanthin, which showed a decreasing trend. The effect of 300 μg/mL showed the most obvious in the 200 μg/mL,300 μg/mL, and 400 μg/mL MLT treatment groups, where the lutein, α-carotene and β-carotene contents were 1.24, 1.14 and 1.31 times higher than those of the control group, respectively. Overall, exogenous MLT at high light intensities had a significant effect on pigment accumulation in Dunaliella bardawil.

The salt-tolerant unicellular alga Dunaliella bardawil FACHB-847 can accumulate large amounts of lutein, but the underlying cause of massive accumulation of lutein is still unknown. In this study, genes encoding two types of carotene hydroxylases, i.e., β-carotene hydroxylase (DbBCH) and cytochrome P450 carotenoid hydroxylase (DbCYP97s; DbCYP97A, DbCYP97B, and DbCYP97C), were cloned from D. bardawil. Their substrate specificities and enzyme activities were tested through functional complementation assays in Escherichia coli. It was showed that DbBCH could catalyze the hydroxylation of the β-rings of both β- and α-carotene, and displayed a low level of e-hydroxylase. Unlike CYP97A from higher plants, DbCYP97A could not hydroxylate β-carotene. DbCYP97A and DbCYP97C showed high hydroxylase activity toward the β-ring and e-ring of α-carotene, respectively. DbCYP97B displayed minor activity toward the β-ring of α-carotene. The high accumulation of lutein in D. bardawil may be due to the multiple pathways for lutein biosynthesis generated from α-carotene with zeinoxanthin or α-cryptoxanthin as intermediates by DbBCH and DbCYP97s. Taken together, this study provides insights for understanding the underlying reason for high production of lutein in the halophilic green alga D. bardawil FACHB-847.

Dunaliella salina can accumulate a large amount of β-carotene which is generally considered to be its terminal product of carotenoid metabolism. In this study, it was proved that D. salina has the ketolase (DsBKT) of catalyzing the synthesis of astaxanthin, the downstream products of β-carotene. Therefore, the reason why D. salina does not synthesize astaxanthin is the purpose of this study. The enzymatic activity of DsBKT was detected by functional complementation assays in Escherichia coli, results showed that DsBKT had efficient ketolase activity toward β-carotene and zeaxanthin to produce astaxanthin, indicating that there were complete astaxanthin-producing genes in Dunaliella. Unlike the induced expression of Lycopene cyclase (catalyzing β-carotene synthesis) under salt stress, the expression of DsBKT was very low under both normal and stress conditions, which may be the main reason why D. salina cannot accumulate astaxanthin. On the contrary, with the astaxanthin-rich Haematococcus pluvialis as a control, its BKT gene was significantly upregulated under salt stress. Further study showed that DsBKT promoter had strong promoter ability and could stably drive the expression of ble-egfp in D. salina. Obviously, DsBKT promoter is not the reason of DsBKT not being expressed which may be caused by Noncoding RNA.

Glycerol-3-phosphate (G3P) is the important precursors for triacylglycerol synthesis, while glycerol-3-phosphate dehydrogenase (GPDH) determines the formation of G3P. In this study, two GDPH genes, Dtgdp1 and Dtgdp2 were isolated and identified from Dunaliella tertiolecta. The full-length Dtgdp1 and Dtgdp2 CDS were 2016 bp and 2094 bp, which encoded two putative protein sequences of 671 and 697 amino acids with predicted molecular weights of 73.64 kDa and 76.73 kDa, respectively. DtGDP1 and DtGDP2 both had a close relationship with those of algal and higher plants. DtGDP1 shared two conserved superfamily (A1 and A2) and four signature motifs (I-IV), and the DtGDP2 showed six signature domains (from motif I to VI) and DAO_C conserved family. Our previous work showed that the triethylamine intervention could greatly increase the triacylglycerol content (up to 80%) of D. tertiolecta. This study aims to investigate the effect of triethylamine on GPDH expression. Results showed that, when treated by triethylamine at 100 ppm and 150 ppm, the expression levels of Dtgdp1 and Dtgpd2 were increased to 5.121- and 56.964-fold compared with the control, respectively. Triethylamine seemed to enhance lipid metabolic flow by inducing the expressions of Dtgdp1 and Dtgdp2 to increase the lipid content, which provides a new insight into the desired pathway of lipid synthesis in algae through genetic engineering.

A two-step strategy was employed to culture Dunaliella tertiolecta, an oleaginous unicellular green alga, combined by the salt stress and sodium azide intervention, to observe their effects on its lipid accumulation. When the algae cultured at different salt concentrations reached the logarithmic growth phase, sodium azide was added. The results showed that the addition of sodium azide significantly increased the lipid content and had no significant effect on cell biomass. The lipid yield and single cell lipid content under 50 μM sodium azide increased by 10.4% and 21.7%. Under the two-step culture condition, combining of the treatment of 50 μM sodium azide and 2.5 M salt stress, the total lipid productivity and single-cell lipid content were 10% and 70.5% higher than that of the control. It seemed that sodium azide and salinity might have a synergistic effect on the lipid accumulation of D. tertiolecta. It can be concluded that sodium azide is an effective inducer of lipid accumulation in D. tertiolecta, and two-stage cultivation is a feasible way to improve lipid accumulation in microalgae.

We examined biomass characteristics and the potential driving factors of different forest types of Quercus spp. secondary forest in Hunan. A total of fifty plots were divided into five forest types: Castanopsis eyri - Rhododendron latoucheae mixed forest (CR), Fagus lucida - Fargesia spathacea mixed forest (FF), Lithocarpus glaber - Damnacanthus indicus + Camellia japonica mixed forest (LDC), C. eyri + Quercus serrata - R. latoucheae mixed forest (CQR), Cyclobalanopsis glauca - Camellia oleifera + R. latoucheae mixed forest (CCR). The biomass of understory vegetation was low in the five forest types, being smaller than 2.3 t·hm对湖南栎类天然次生林不同林分类型的林下植被生物量特征及其影响因素进行研究。结果表明: 将50块样地划分为甜槠-鹿角杜鹃混交林、亮叶水青冈-箭竹混交林、石栎-虎刺+山茶混交林、甜储+枹栎-鹿角杜鹃混交林、青冈栎-油茶+杜鹃混交林5种林分类型。5种林分的林下植被生物量均较低,不超过2.3 t·hm

The salt-tolerant unicellular alga

In the carotenoid biosynthesis, lycopene β-cyclase (LCYb) is a key regulatory enzyme involved in the conversion of lycopene into β-carotene. Under stress conditions, such as high salinity, high light and nutrient deprivation, large amounts of β-carotene can be accumulated in Dunaliella bardawil. To study on the molecular responses of salt stress in D. bardawil is of great significance to reveal the mechanisms of salt tolerance and engineer crop plants to be salt-tolerant. In this study, the full-length coding sequence of lcyb from D. bardawil (Dblcyb, GenBank: KX218392) was isolated by transcriptome sequencing. Then, the genomic sequence, promoter and terminator regions of Dblcyb were isolated by genome walking. The Dblcyb promoter (GenBank: KX218393) contained several typical transcription boxes, multiple light response elements and a salt-regulated element (SRE, GT1GMSCAM4). Dbpsy and Dblcyb responsible for β-carotene biosynthesis in D. bardawil was shown to be up-regulated under salt stress and their promoters contained the common SRE. By element deletion analysis and using Ble-EGFP as the reporter, the salt-inducible SRE was confirmed to confer salt-induced expression of Dblcyb promoter. It was indicated that the salt-regulated expression of Dblcyb may be attributed to the salt-responsive element (GT1GMSCAM4) and the GT-rich region in its genomic sequence.

Dunaliella tertiolecta is a highly oil-producing microalgae. Here, we report its de novo transcriptome assembly and quantitative gene expression analysis of the intervention of triethylamine, with a focus on the complex interactions of pathways involved in the production of triacylglycerol (TAG) biofuel precursors. After growing under 100 ppm triethylamine, we quantified the cellular content of the major biomolecules, including total lipids, single cell oil content, and lipid components. The transcriptome was assembled de novo and the main functional classes, related pathways, and expression of important genes were quantified by the mapping of reads to the transcriptome. Almost 65,925 high-quality readings were produced on the Illumina HiSeq sequencing platform. In addition to the observed overexpression of the fatty acid synthesis pathway, TAG production during triethylamine was not through the Kennedy pathway, but the bypass pathway by high expression of phosphate: diacylglycerol acyltransferase. The glycolytic pathway has also been down-regulated, not only in the cytoplasm but also in the chloroplast. Triosephosphate translocator was downregulated, and the DNA binding with One Finger protein gene was upregulated. The quantitative transcriptome study reveals a broad overview of how triethylamine stress leads to excessive TAG production in Dunaliella, and provides various genetic engineering goals and strategies to improve biofuel precursors in oleaginous microalgae.

Butylparaben sodium (BP), sodium diacetate (SDA) and potassium sorbate (PS) are safe and internationally recognized preservatives. The aim of this study is to further evaluate their toxicities using microalgae cells, and a comparison is made with their mammalian cell cytotoxicities. Unicellular Dunaliella tertiolecta, was employed to test the possible toxicities of BP, SDA and PS. The results show that the three preservatives have a negative effect on D. tertiolecta, as manifested by a strong decrease in chlorophyll and carotenoid content, viable algal cells, and superoxide dismutase (SOD) and catalase (CAT) activities. SDA and PS had small effects on the normal hepatocytes HL7702, but similar to that for MCF-10A cells, BP is toxic. The effective concentration (EC50) value for HL7702 is 215.97 mg L−1. It is concluded that BP, SDA and PS have low toxicities to D. tertiolecta under slightly alkaline conditions, while under acidic conditions, SDA has moderate toxicity and PS has high toxicity. The sensitivity of algal cells is higher than that of HL7702 cells under slightly alkaline conditions, and is even more sensitive under acidic conditions. D. tertiolecta can be used as a pre-screen for toxicity testing.

Microalgae lipids have attracted great attention in the world as a result of their potential use for biodiesel productions. Microalgae are cultivated in photoautotrophic conditions in most cases, but several species are able to grow under heterotrophic conditions, in which microalgae are cultivated in the dark where the cell growth and reproduction are supported by organic carbons. This perspective is covering the related studies concerning the difference between hetero- and autotrophic cultivation of microalgae. The auto- and heterotrophic central carbon metabolic pathways in microalgae are described, and the catalyzing reactions of several key metabolic enzymes and their corresponding changes in the protein level are summarized. Under adverse environmental conditions, such as nutrient deprivation, microalgae have the ability to highly store energy by forming triacylglycerol (TAG), the reason for which is analyzed. In addition, the biosynthesis of fatty acids and TAGs and their difference between auto- and heterotrophic conditions are compared at the molecular level. The positive regulatory enzymes, such as glucose transporter protein, fructose-1,6-bisphosphate aldolase, and glycerol-3-phosphate dehydrogenase, and the negative regulation enzymes, such as triose phosphate isomerase, played a crucial role in the lipid accumulation auto- and heterotrophic conditions.

Triacylglycerol (TAG) is an important product in oil-producing organisms. Biosynthesis of TAG can be completed through either esterification of fatty acids to glycerol backbone, or through esterification of 2-monoacylglycerol. This review will focus on the former pathway in which two precursors, fatty acid and glycerol-3-phosphate (G3P), are required for TAG formation. Tremendous progress has been made about the enzymes or genes that regulate the biosynthetic pathway of TAG. However, much attention has been paid to the fatty acid provision and the esterification process, while the possible role of G3P is largely neglected. Glycerol is extensively studied on its usage as carbon source for value-added products, but the modification of glycerol metabolism, which is directly associated with G3P synthesis, is seldom recognized in lipid investigations. The relevance among glycerol metabolism, G3P synthesis and lipid production is described, and the role of G3P in glycerol metabolism and lipid production are discussed in detail with an emphasis on how G3P affects lipid production through the modulation of glycerol metabolism. Observations of lipid metabolic changes due to glycerol related disruption in mammals, plants, and microorganisms are introduced. Altering glycerol metabolism results in the changes of final lipid content. Possible regulatory mechanisms concerning the relationship between glycerol metabolism and lipid production are summarized.

To explore micro-or nanoscintillator with a controllable architecture, a novel facile hydrothermal method easy for commercial run was used to synthesize pure and Ce doped β-NaLuF4 microcrystals at 453K. The morphology of uniform hexagonal prism with 3.3μm in diameter and 1.4 μm in thickness, respectively, is presented by the results of scanning electron microscopy (SEM). Powder X-ray diffraction (PXRD) patterns show the products are both pure hexagonal phase. Different from the undoped product without any irradiation, the Ce doped product has given strong broad band emission attributed to 5d4f transition of Ce3+, which can be potentially used as scintillator for biomedical imaging and detectors for high energy such as X-ray and γray. This synthetical strategy extends the understanding about nanomaterial chemistry and can be also useful for other systems such as fluorides, oxides and sulfides.

The halophilic green alga Dunaliella bardawil FACHB-847 is rich in lutein and α-carotene, which has great potential for carotenoid production in open ponds. In this study, genes encoding lycopene β- and ε-cyclases (DbLcyB and DbLcyE) from D. bardawil FACHB-847 were functionally identified by genetic complementation in E. coli. The bifunctional DbLcyB not only catalyzed the formation of both mono- and bi-cyclic β-rings with a major β-cyclase activity, but also possessed a weak ε-cyclase activity. In contrast, DbLcyE preferred to convert lycopene into monocyclic δ-carotene, and possessed a weak β-monocyclase activity. Lutein and α-carotene were the prominent carotenoids in D. bardawil FACHB-847, which was in agreement with the result of genetic complementation of co-expression of DbLcyB and DbLcyE in E. coli with α-carotene as the prominent product. The bifunctional DbLcyB and DbLcyE may contribute to the high accumulation of α-carotene in D. bardawil FACHB-847. Interestingly, the accumulation of lutein in D. bardawil FACHB-847 was more sensitive to salt stress, while the accumulation of β-carotene in D. salina CCAP 19/18 was induced by salt stress. In brief, the production of different carotenoid compositions from these two Dunaliella species can be induced by different growth conditions.

The incorporation of power generation derived from renewable energy sources, or renewable power generation (RPG), into conventional electric power grids has been rapidly increasing on a large scale in recent years. However, this process can be expected to inevitably increase the uncertainty associated with transmission line investment owing to the inherent uncertainty associated with RPG. While robust transmission expansion planning (RTEP) has been commonly employed for optimizing transmission line investments, this method suffers from serious disadvantages such as the neglect of available RPG probability information, overly conservative solutions, and exceedingly time consuming solution processes. The present work addresses these disadvantages by modeling the probability of RPG uncertainty according to RPG output probabilities obtained over a long-term planning horizon based on available historical data using a hybrid probability uncertainty set constructed using 1-norm and ∞-norm metrics. A probability-driven RTEP model is then proposed to obtain an optimal investment strategy that provides a security guarantee under the worst-case RPG probability distribution, while alleviating the need for overly conservative solutions with high total expansion costs. In addition, a modified column-and-constraint generation algorithm is developed to solve the proposed tri-level probability-driven RTEP model, where the large-scale inner bi-level component of the optimization problem is decomposed into several small-scale linear models that can be solved in parallel. The proposed algorithm requires no dual variables in the inner problem and eliminates all highly non-convex bilinear terms like those obtained in conventional RTEP solution algorithms. This can effectively increase the computational speed of the solution process. The effectiveness, good applicability, and robustness of the proposed model and solution algorithm are demonstrated by numerical applications based on a Garver’s 6-bus test system and an existing electric grid system in northwestern China.

利用固相法合成了Li + 、Eu 3+ 掺杂的NaY(WO 4 ) 2 红色荧光粉, 并且用X射线粉末衍射仪和紫外-可见光谱仪进行了表征。研究发现纯相产物可以在1100℃下制备, 然而稳定存在的温度区间仅约100℃。和已报道的燃烧法产物不同, Eu 3+ 掺杂产物的发光性质证实了浓度猝灭现象的存在, 掺杂9mol％时发光最强, 有效激发波长是393 nm, 发射光谱体现为高选择性的Eu 3+ 的 5 D 0 → 7 F 2 电偶极跃迁, 因此适合于解决白光LED中缺乏红光成分的问题。Li ＋ 掺杂既没有改变Eu 3+ 红光发射的择优性, 又能够调节发光强度。研究发现合适的Li ＋ 浓度可以增强发光, 但是浓度过大或过小对发光不利, 掺杂30mol％时发光最强。这种变化规律可以归因于点阵缺陷增加和Y原子格位不对称性增强对发光强度的不同影响之间竞争的结果。

Eu3+ doped CdWO4 nanorods, with nearly uniform nanoscale was synthesized via a novel simple hydrothermal method easy for commercial run at 160 °C, of which the average dimensions are about 250, 50 and 20 nm in length, width and height respectively from the result of transmission electron microscopy (TEM). Powder X-ray diffraction (PXRD) pattern shows the product is pure wolframite structure. Different from undoped products showed brilliant blue-green irradiation and block crystals with multi-emission bands in red light range, the Eu doped nanorods give preferred strong 5D0→7F2 transition and are excellent red phosphor with high color purity supported by the photoluminescent (PL) measurements and ultraviolet visible diffuse reflectance spectroscopy (UV-Vis DRS). This suggests that a combination of the Eu3+ doped and undoped products are potential to realize the white lighting LED with blue, green and red components.

In the carotenoid biosynthesis, lycopene β-cyclase (LCYb) is a key regulatory enzyme involved in the conversion of lycopene into β-carotene. Under stress conditions, such as high salinity, high light and nutrient deprivation, large amounts of β-carotene can be accumulated in Dunaliella bardawil. To study on the molecular responses of salt stress in D. bardawil is of great significance to reveal the mechanisms of salt tolerance and engineer crop plants to be salt-tolerant. In this study, the full-length coding sequence of lcyb from D. bardawil (Dblcyb, GenBank: KX218392) was isolated by transcriptome sequencing. Then, the genomic sequence, promoter and terminator regions of Dblcyb were isolated by genome walking. The Dblcyb promoter (GenBank: KX218393) contained several typical transcription boxes, multiple light response elements and a salt-regulated element (SRE, GT1GMSCAM4). Dbpsy and Dblcyb responsible for β-carotene biosynthesis in D. bardawil was shown to be up-regulated under salt stress and their promoters contained the common SRE. By element deletion analysis and using Ble-EGFP as the reporter, the salt-inducible SRE was confirmed to confer salt-induced expression of Dblcyb promoter. It was indicated that the salt-regulated expression of Dblcyb may be attributed to the salt-responsive element (GT1GMSCAM4) and the GT-rich region in its genomic sequence.

In this work, a new type of lead tungstate crystal (Pb 3 WO 6 ) was synthesized by hydrothermal method under high temperature and high pressure. Crystal structure was characterized by single-crystal X-ray structure determination. Pb 3 WO 6 (monoclinic, P 2 1 / c , (No. 14), a = 7.8643(6) A, b = 9.2036(8) A, c = 9.0652(8) A, β = 90.299(5)°, V = 656.13(2) A 3 , Z = 4) exhibited two different layered arrangements of edge-shared octahedral WO 6 with six oxygen coordination along a axis. Thermal stability was investigated by TG–DSC and two phase transformations were observed at about 647 and 748 °C, respectively. Finally, VUV excitation and emission spectra of Pb 3 WO 6 crystal were studied under the temperature 14 K. The results revealed that samples had weak luminescent properties, which exhibited excitation peak at 285 nm and emission peak at 460 nm at low temperature.

The long-persistent properties of the phosphor SrAl2O4∶Eu2+,Dy3+(or SAO∶ED) have been modulated by doping with Yb3+ or/and Er3+ according to the energy-level model proposed recently by Dorenbos.To analyze the decay process,we use a new developed analytical model instead of the usually adopted empirical one.The decay curves have been analyzed by this model.It is found that the doped Yb3+ does enhance the light-emitting intensity of SAO∶ED as predicted by Dorenbos,yet it acts not as a light-emitting center,but as an auxiliary excitation center.In consistent with Dorenbos' prediction,the doped Er3+ does act as a trap center.But when SAO∶ED is co-doped with Er3+ and Yb3+,Er3+ plays a role,which exerts an effect of re-trapping,increases the initial light-emitting intensity and reduces the decay time,but the figure of merit of light-emitting does not change significantly.

In this work, large-scale three-dimensional "flake-ball" microarchitectures of Eu(3+) doped white light hydroxyl sodium yttrium tungstate were prepared by the well-known hydrothermal approach at 180 degrees C for 48 h in the presence of triblock-copolymer poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) (P123). NaY(WO(4))(2):Eu(3+) phosphor was formed by annealing the hydrothermal product at approximately 630 degrees C for 2 h. A time-dependent microstructure evolution study was performed under hydrothermal reaction. The evolution process is the self-assembly process of P123, and the effects of other reaction parameters, such as influence of the concentration of P123 on morphology, and the influence of temperature on PL. The mechanism by which the "flake-ball" particles are formed is discussed in detail. The PL spectra of Eu(3+)-doped hydroxyl sodium yttrium tungstate phosphor contain two parts: the broad blue-green band and the (5)D(0)--(7)F(J) (J = 1, and 2) characteristic transition of Eu(3+). This approach provides a facile route for the production of high-quality hydroxyl sodium yttrium tungstate microstructures with an interesting optical property.

Large-scale micro- and nano-sized Eu3+-doped gadolinium tungstate and molybdate Gd2MO6:Eu3+ (M=Mo, W) red phosphors with special morphologies have been successfully prepared via an efficient molten salt synthesis (MSS) method at 950°C for 6 h using NaCl and as the reaction medium. The results of X-ray powder diffraction patterns indicate that Gd2MoO6 and Gd2WO6 have monoclinic structures. The scanning electronic microscope and transmission electron microscope studies revealed that the samples of Gd2WO6:Eu3+ and Gd2MoO6:Eu3+ phosphors obtained by the MSS method in NaCl medium have a sphere-like morphology, and the corresponding samples obtained in KCl medium have rod-like morphologies. For the Gd2MoO6:Eu3+ phosphor obtained in NaCl and KCl media, the sphere-like particles had an average grain size of ∼100 nm, and the size of the rod-like particles ranged from 200 to 400 nm in length, and ∼150 nm in width, respectively. Compared with the same products obtained by the solid-state reaction we had reported, the luminescent properties of Gd2MO6:Eu3+ (M=Mo, W) are largely dependent on their morphology and crystal size prepared using different fluxes of NaCl and KCl. The reaction time and temperature also play an important role in the crystallization of the samples.

Structure, magnetization, heat capacity, thermoelectric properties of Ba 8 Cu 6 Ge 40 are investigated. Ba 8 Cu 6 Ge 40 crystallizes in clathrate I type structure with unit cell a = 10.6850 (1) A. Ba 8 Cu 6 Ge 40 exhibits diamagnetic susceptibility −0 . 024 emu/g T, Einstein temperature 70 K and Debye temperature 306 K. The electrical conductivity σ , Seebeck coefficient S , thermal conductivity κ , and the thermoelectric figure of merit ZT of Ba 8 Cu 6 Ge 40 from 2 K to 300 K are reported.

The luminescent characteristics of RE (RE3+ = Eu, Tb, Dy, Sm and Tm)-doped K2GdZr(PO4)3 have been investigated. The band in the range of 130–157 nm in the VUV excitation spectra of these compounds is attributed to the host lattice or PO43− group absorption and the band from 157 nm to 215 nm with the maximum at 188 nm is due to the O–Zr charge transfer transition. For Eu3+-doped sample, the relatively weak band of O2−–Eu3+ charge transfer (CTB) at 222 nm is observed and for Tb3+-doped sample, the band at 223 nm is related to the 4f–5d spin-allowed transition of Tb3+. For Dy3+- and Sm3+-doped samples, the O2−–Dy3+ and O2−–Sm3+ CTBs have not been observed, probably due to the 2p electrons of oxygen tightly bound to the zirconium ion in the host lattice. In Tm3+-doped sample, the weak O2−–Tm3+ CTB is located at 170 nm. It is observed that there is energy transfer between the host and the luminescent activators (e.g. Eu3+, Tb3+ and Sm3+) except for Tm3+.

The crystal structure of Lu2WO6 was determined from Rietveld refinement of X-ray powder diffraction data. It crystallizes in the monoclinic system belonging to space group P2/c (No.13) with lattice parameters: a = 7.5180(1) A, b = 5.2675(1) A, c = 11.2245(2) A, β = 104.61(0)°, V = 430.14(11) A3, Z = 4. The conventional R indices obtained are Rp = 0.090, Rwp = 0.119 and RB = 0.075. The infinite chain comprised of Lu(2)O8 dodecahedra and Lu(3)O7 decahedra makes up the layer A, and the infinite straight chain is built of four-ring of polyhedra in which the WO6 and Lu(1)O8 groups alternate in layer B, finally, this structure is formed by stacking of these two layers with edge-shared. The X-ray and UV excited luminescence properties of Eu3+ and Pr3+ in Lu2WO6 were investigated: Eu3+ shows high luminescent efficiency in emitting red light, and Pr3+ is less efficient in emitting orange light. The luminescent mechanism of Eu3+ and Pr3+ in the matrix of Lu2WO6 is much different.

A new efficient blue phosphor, Eu2+ activated SrZnP2O7, has been synthesized at 1000 °C under reduced atmosphere and the crystal structure and photoluminescence properties have been investigated. The crystal structure of SrZnP2O7 was obtained via Rietveld refinement of powder X-ray diffraction (XRD) pattern. It was found that SrZnP2O7 crystallizes in space group of P21/n (no. 14), Z=4, and the unit cell dimensions are: a=5.30906(2) A, b=8.21392(3) A, c=12.73595(5) A, β=90.1573(3)°, and V=555.390(3) A3. Under ultraviolet excitation (200–400 nm), efficient Eu2+ emission peaked at 420 nm was observed, of which the luminescent efficiency at the optimal concentration of Eu2+ (4 mol%) was estimated to be 96% as that of BaMgAl10O17:Eu2+. Hence, the SrZnP2O7:Eu2+ exhibit great potential as a phosphor in different applications, such as ultraviolet light emitting diode and photo-therapy lamps.

A layered borogermanate with three-dimensional microporosity within the layers, K(4)[B(8)Ge(2)O(17)(OH)(2)] (monoclinic, space group: C2/c; a=12.095(2), b=6.7979(14), c=19.944(4) A; beta=93.04(3) degrees ; V=1637.6(6) A(3); Z=4), has been synthesized in a flux of potassium borate. Because of its three-dimensional pore structure and thermal stability, the compound has the potential to eventually form nanocomposites with polymers and to be processed into thin microporous films.

Three rare earth borosilicate oxyapatites, RE {sub 5}Si{sub 2}BO{sub 13} (RE=La, Gd, Y), were synthesized via wet chemical method, of which RE {sub 5}Si{sub 2}BO{sub 13} (RE=Gd, Y) were first reported in this work. In the three oxyapatites, [BO{sub 4}] and [SiO{sub 4}] share the [TO{sub 4}] tetrahedral oxyanion site, and RE {sup 3+} ions occupy all metal sites. The differential scanning calorimetry-thermo gravimetry measurements and high temperature powder X-ray diffraction pattern revealed a vitrification process within 300-1200 deg. C, which was due to the glass-forming nature of borosilicates. From the VUV excitation spectra of Eu{sup 3+} and Tb{sup 3+} in RE {sub 5}Si{sub 2}BO{sub 13}, the optical band gaps were found to be 6.31, 6.54 and 6.72 eV for RE {sub 5}Si{sub 2}BO{sub 13} (RE=La, Gd, Y), respectively. The emission and excitation bands of Eu{sup 3+} and Tb{sup 3+} are discussed relating with their coordination environments. Among the three hosts, Y{sub 5}Si{sub 2}BO{sub 13} would be the best for Eu{sup 3+} and Tb{sup 3+}-doped phosphors. - Graphical abstract: The perspective view of RE {sub 5}Si{sub 2}BO{sub 13} (RE=La, Gd, Y) oxyapatite along [001] direction. All non-tetrahedral metal sites are occupied by RE {sup 3+}, and the tetrahedral sites bymore » SiO{sub 4} and BO{sub 4} groups. Y{sub 5}Si{sub 2}BO{sub 13} is a good host for both Eu{sup 3+} and Tb{sup 3+} activated phosphors.« less

Two new anhydrous sodium borophosphates with one-dimensional structure, Na3B6PO13 (1) and Na3BP2O8 (2), were synthesized by low-temperature molten salts techniques using boric acid and sodium dihydrogen phosphate as flux, respectively. The crystal structures were solved by means of single-crystal X-ray diffraction (1, orthorhombic, Pnma (no. 62), a = 9.3727 ( 4 ) A , b = 16.2307 ( 7 ) A , c = 6.7232 ( 3 ) A , Z = 4 ; 2 , monoclinic, C2/c (no. 15), a = 12.567 ( 4 ) A , b = 10.290 ( 3 ) A , c = 10.210 ( 3 ) A , β = 92.492 ( 5 ) ° , Z = 8 ). Compound 1 is characterized by an infinite chain of ∞ 1 { [ B 6 PO 13 ] } 3 - containing eight-membered rings in which all vertexes of borate groups contribute to interconnection. Compound 2 reveals an infinite straight chain ∞ 1 { [ BP 2 O 8 ] } 3 - built of vertex-sharing four-membered rings, and chains in neighboring layers arranged along different orientations. The relations between structures and the synthetic conditions with only traced water are discussed.

Two new lanthanum phosphite hydrates, La2(H2O)(HPO3)3 (1) and La2(H2O)2(HPO3)3 (2), were synthesized by a hydrothermal method. Their crystal structures were determined by X-ray single-crystal method (1, monoclinic, C 2 / c (No. 15); a = 20.820 ( 5 ) A , b = 6.717 ( 2 ) A , c = 14.123 ( 3 ) A , β = 101.261 ( 3 ) ° , V = 1937.0 ( 8 ) A 3 ; Z = 8 ; 2, triclinic, P-1 (No. 2); a = 8.168 ( 3 ) A , b = 8.439 ( 2 ) A , c = 9.337 ( 3 ) A , α = 115.641 ( 3 ) ° , β = 98.655 ( 3 ) ° , γ = 105.124 ( 3 ) ° , V = 533.87 ( 1 ) A 3 , Z = 2 ). Both crystal structures present three-dimensional open-framework structures containing channels, and 1 adopts intersecting type. In the two structures, the face-sharing dimers of LaOn ( n = 8 , 9 ) were observed. Other characterizations by IR and TG–DSC were also described. Furthermore, both the compounds doped with Ce+3 showed intensive broad emission band around 340 nm under UV excitation.

The first lutetium diphosphate NH4LuP2O7 has been prepared by a two-step, low-temperature self-flux synthesis in the presence of the F– anion, functioning as a mineralizer, which played a significant role in the synthetic process. The crystal structure has been characterized by single-crystal X-ray diffraction. The title compound crystallizes in a monoclinic system of the space group P21/c (No. 14), a = 7.651(2) A, b = 10.789(2) A, c = 8.577(2) A, β = 105.75(3)°, V = 681.4(2) A3, Z = 4. The three-dimensional framework of NH4LuP2O7, composed of Lu2P4O14 building units formed by vertex-linking LuO6 and P2O7 goups, is isostructural with compounds of the type KAlP2O7 in the ternary diphosphate(AIMIIIP2O7) system. X-ray-excited luminescence measurements of Ce-activated samples show insteresting scintillation properties with a short decay time of 16 ns at room temperature. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

A new borophosphate NH4Cd(H2O)2(BP2O8)·0.72H2O has been synthesized under mild hydrothermal conditions. The crystal structure was characterized by single crystal X-ray diffraction method. Crystal Data: Hexagonal, P65 (No.176), a = 9.6978(16) A, c = 16.026(4) A, V = 1305.3(4) A3, Z = 6, R1 = 0.0256 and wR2 = 0.0665 for 1409 observed unique reflections and 146 variables. The structure is characterized by corner-sharing PO4 and BO4 tetrahedra, leading to infinite helical {[BP2O8]3−} ribbons, which are connected by CdO4(H2O)2 coordination octahedra. Nevertheless, the structure reveals significant difference from its other ammonium containing analogues with respect to the occupations of NH4+ and the metal cation. The abnormal changes of the unit cells comparing with cadmium borophosphates with other counter cations were presumably due to the anisotropic hydrogen bonds along the c-axis or on the ab-plane. Its UV-Vis fluorescence property was investigated for the first time.

Two transition-metal phosphites, Na2[M(HPO3)2] (M = Fe, Co) with a new structure type have been synthesised under mild hydrothermal conditions and the solid-state structures have been elucidated by single-crystal X-ray diffraction studies. The structures are of a new type with the following data: orthorhombic, Pnma, a = 12.169(4), b = 5.441(2) and c = 9.146(3) A for the iron species 1 and a = 12.091(3), b = 5.400(4) and c = 9.115(2) A for the cobalt compound 2, with Z = 4. The crystal structures of these compounds are isotypic and built up from a 3D open framework with 4-, 6- and 12-membered polyhedral rings of vertex-linked MO6 and HPO3 building units. The inorganic frameworks contains 12-membered ring channel systems in which the sodium ions are located. The topology of this structure type is remarkably similar to that of the aeschynite CaTa2O6 with much larger channels. Magnetic measurements of Na2[Co(HPO3)2] show different magnetic features in the low-temperature (5–30 K) and high-temperature ranges (100–320 K) suggesting the possible existence of a complex magnetic structure. Antiferromagnetic ordering can be observed as a broadened cusp in χ–1 at θ = 2.6 K. For Na2[Fe(HPO3)2], the magnetic behavior follows the Curie–Weiss law with μeff = 5.41 μB, fitted for 100–320 K. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

Yellow Pb3WO6 crystals are hydrothermally prepared from PbO and WO3 using aqueous NaOH solution as a mineralizer (autoclave, 300 °C, 600—800 bar).