Combination Of Bi Research Articles

An anthraquinone-based bismuth-iron metal-organic framework as an efficient photoanode in photoelectrochemical cells.

Metal-organic frameworks (MOFs) are appealing candidate materials to design new photoelectrodes for use in solar energy conversion because of their modular nature and chemical versatility. However, to date there are few examples of MOFs that can be directly used as photoelectrodes, for which they must be able to afford charge separation upon light absorption, and promote the catalytic dissociation of water molecules, while maintaining structural integrity. Here, we have explored the use of the organic linker anthraquinone-2, 6-disulfonate (2, 6-AQDS) for the preparation of MOFs to be used as photoanodes. Thus, the reaction of 2, 6-AQDS with Bi(iii) or a combination of Bi(iii) and Fe(iii) resulted in two new MOFs, BiPF-10 and BiFePF-15, respectively. They display similar structural features, where the metal elements are disposed in inorganic-layer building units, which are pillared by the organic linkers by coordination bonds through the sulfonic acid groups. We show that the introduction of iron in the structure plays a crucial role for the practical use of the MOFs as a robust photoelectrode in a photoelectrochemical cell, producing as much as 1.23 mmol H2 cm-2 with the use of BiFePF-15 as photoanode. By means of time-resolved and electrochemical impedance spectroscopic studies we have been able to unravel the charge transfer mechanism, which involves the formation of a radical intermediate species, exhibiting a longer-lived lifetime by the presence of the iron-oxo clusters in BiFePF-15 to reduce the charge transfer resistance.

Fabrication of Bi/BiOCOOH/PVDF with improved photocatalytic activity for the degradation of ciprofloxacin

The development of a low-cost and recyclable method for wastewater treatment has been a major challenge. Polyvinylidene fluoride (PVDF) membranes have received considerable attention owing to their excellent mechanical strength, unique antioxidant properties, and low cost. In this study, Bi/BiOCOOH/PVDF composite membrane materials were prepared using a simple two-step solvent thermal method and phase conversion method. The results showed that under the synergistic action of adsorption and photocatalysis, the photocatalytic degradation efficiency of Bi/BiOCOOH composite material and Bi/BiOCOOH/PVDF composite membrane material for ciprofloxacin (CIP) was much higher than that of BiOCOOH. The introduction of PVDF acted as a carrier, improved the adsorption of the catalytic material to CIP, and facilitated the effective collision of the photocatalytic active site and CIP. The experimental results and theoretical calculations confirmed that the combination of Bi and BiOCOOH effectively improved the light absorption capacity and photocatalytic performance. The reproducibility test revealed that the small amount of new composite catalyst for Bi/BiOCOOH/PVDF as a carrier was lost and that the Bi/BiOCOOH/PVDF catalyst still had high catalytic activity. In addition, the influence of water matrix factors, such as pH and anion, on the photocatalytic degradation experiment was investigated, which would provide some reference for the actual wastewater treatment of the composite catalyst. This study demonstrates a photocatalytic activation mechanism between metals and semiconductors and provides some basis for constructing catalysts for the synergistic and effective treatment of water pollution through a combined adsorption and photocatalysis process.

Bi2Te3 Thin Films Deposited by the Combination of Bi and Te Plasmas in a PLD Process

Bismuth telluride thin films were grown by pulsed laser deposition by implementing a novel method that combines both Te and Bi plasmas resulting from the laser ablation of individual Bi and Te targets. Furthermore, the mean kinetic ion energy and density of the plasmas, as estimated by TOF curves obtained from Langmuir probe measurements, were used as control parameters for the deposition process. The obtained thin films exhibit a metallic mirror-like appearance and present good adhesion to the substrate. Morphology of the thin films was observed by SEM, yielding smooth surfaces where particulates were also observed (splashing). Chemical composition analysis obtained by EDS showed that apparently the films have a Te-rich composition (ratio of Te/Bi of 3); however, Te excess arises from the splashing as revealed by the structural characterization (XRD and Raman spectroscopy). The XRD pattern indicated that depositions have the rhombohedral (D3d5 (R3¯m)) structure of Bi2Te3. Likewise, Raman spectra exhibited the presence of signals that correspond to Eg2, A1u2 and A1g2(LO) vibrational modes of the same rhombohedral phase of Bi2Te3. Additionally, oxidation states, analyzed by XPS, resulted in signals associated to Bi3+ and Te2- that correspond to the Bi2Te3 compound. Finally, surface topology and thickness profiles were obtained from AFM measurements, confirming a combination of a smooth surface with particulates on top of it and a film thickness of 400 nm.

Polar–Nonpolar Transition-Type Negative Thermal Expansion with 11.1% Volume Shrinkage by Design

Chemical substitution for the tuning of the working temperature of phase-transition-type negative thermal expansion (NTE) materials generally reduces the volume shrinkage during the transition. We have investigated the effects of electron doping and reduction of 6s2 lone-pair activity in PbVO3 with a large polar distortion (c/a = 1.23) and found that the combination of Bi and Sr substitutions for Pb enables a temperature-induced polar to non-polar transition with 11% volume shrinkage, even larger than the pressure-induced volume collapse of PbVO3 (∼10.6%), and is the largest value among the NTE materials reported so far. The domain structure of the coexisting cubic and tetragonal phases with such a huge volume difference was successfully observed by high-angle annular dark-field scanning transmission electron microscopy and the spatial distribution of domains by Bragg coherent X-ray diffraction imaging. The temperature hysteresis is reduced by repeated heating/cooling cycles, suggesting that the changes in the domain structure dominate the NTE properties.

A phase Ia/Ib, dose-escalation/expansion study of BI 907828 in combination with BI 754091 (ezabenlimab) and BI 754111 in patients (pts) with advanced solid tumors.

3095 Background: Preclinical data show that combining a murine double minute 2–tumor protein 53 (MDM2–p53) antagonist with immune checkpoint inhibitors produces anti-tumor effects in multiple tumor types. This Phase Ia/Ib study (NCT03964233) is assessing BI 907828, a MDM2–p53 antagonist, combined with immune checkpoint inhibitors in TP53 wild-type cancers. Methods: In Phase Ia (dose escalation), pts with advanced/metastatic solid tumors received escalating doses of BI 907828 guided by a Bayesian Logistic Regression Model (starting dose 10 mg orally) plus ezabenlimab 240 mg (anti-PD-1 antibody) and BI 754111 600 mg (anti-LAG-3 antibody) every 21 days (q3w). Primary endpoint was the maximum tolerated dose (MTD) of BI 907828 based on the number of pts with dose-limiting toxicities (DLTs) during cycle one. During Phase Ia, other studies indicated a lack of added efficacy when BI 754111 was combined with ezabenlimab; therefore, the study design was updated to switch the dose escalation to the doublet combination of BI 907828 plus ezabenlimab. Results: A total of 11 pts received the triplet combination at 10/20/30/45 mg dose levels (DL; n = 3/3/3/2 respectively); all have discontinued treatment. No DLTs were reported in cycle one; MTD was not reached. As of 20th January 2022, 15 pts have received the doublet combination at 30/45 mg DLs (n = 10/5 respectively). One pt (45 mg) had a DLT during cycle one: G2 neutropenia. Four DLTs were reported after cycle one: G3 anemia (30 mg); G2 thrombocytopenia (45 mg); and G3 neutropenia and G4 thrombocytopenia (45 mg). G≥3 adverse events occurred in eight pts; most commonly anemia (n = 6), thrombocytopenia (n = 4) and lymphopenia (n = 3). There were no notable safety findings with BI 907828 45 mg q3w, the recommended dose for expansion (RDE) for BI 907828 monotherapy. Nine of the 15 pts who received doublet therapy were evaluable for response; four had a confirmed partial response (PR; 30 mg, n = 1; 45 mg, n = 3), two biliary tract carcinoma, one urothelial carcinoma, and one myxoid liposarcoma; one had an unconfirmed PR (30 mg) with adenocarcinoma (primary site intrahepatic cholangiocarcinoma). Four pts with liposarcoma and gastric cancer had stable disease. MTD will be reported. In Phase Ib, pts will receive the RDE of BI 907828 plus 240 mg ezabenlimab (q3w). Pts will be recruited to two cohorts: soft tissue sarcomas (liposarcoma, undifferentiated pleomorphic sarcoma, myxofibrosarcoma, synovial sarcoma and leiomyosarcoma) and selected MDM2-amplified tumors (NSCLC, gastric adenocarcinoma, urothelial carcinoma, and biliary tract carcinoma). Primary endpoints are progression-free survival and objective response (RECIST 1.1). Conclusions: The doublet combination of BI 907828 plus ezabenlimab showed a manageable safety profile and early signs of anti-tumor activity. Eleven pts remain on treatment; recruitment is ongoing. Clinical trial information: NCT03964233.

Anthropogenic Sources Dominate Foliar Chromium Dust Deposition in a Mining-Based Urban Region of South Africa.

Dust pollution can be severe in urban centers near mines and smelters. Identification of dust sources and assessing dust capturing plant morphological traits may help address the problem. A chromium (Cr) mining and ferrochrome smelting region in Sekhukhuneland, South Africa, was investigated to identify the sources of Cr in soil and plant leaf surfaces and to evaluate the association between Cr sources and plant morphology. Combinations of bi- and multivariate statistical analysis techniques were applied. Non-significant relation between Cr quantities in surface soil and on leaf surfaces suggested negligible Cr dust contribution from soil to leaves. Association among Cr, Fe, Mg, Al, and Si levels on leaf surfaces confirmed their shared origin, possibly from chromite containing dust dispersed by mines, smelters, roads, and tailings. Both plant morphology and Cr sources (number and proximity to mines and roads) conjointly determined Cr dust deposition on leaf surfaces. Air mass movement patterns further identified local polluters, i.e., mines, ferrochrome smelters, and roads, as dominant dust sources in the region. Common plant species showed Cr dust adhesion favouring traits (plant tallness, larger leaf area, dense epicuticular wax structures, and larger stomata) and projected dust mitigation prospects for Sekhukhuneland.

Bi@C Nanospheres with the Unique Petaloid Core-Shell Structure Anchored on Porous Graphene Nanosheets as an Anode for Stable Sodium- and Potassium-Ion Batteries.

Bismuth (Bi) has emerged as a prospective candidate as Na-ion and potassium-ion battery anodes because of its unique advantages of low cost, high theoretical gravimetric capacity (386 mAh g-1), and superior volumetric capacity (3800 mAh cm-3). However, the low electronic conductivity and the huge volume expansion of Bi during the alloying/dealloying reactions are extremely detrimental to cycling stability, which seriously hinder its practical application. To overcome these issues, we propose a rational design: Bi@C nanospheres with the unique petaloid core-shell structure are synthesized in one step for the first time and then combined with different contents of graphene (GR) nanosheets to form the composites Bi@C@GR. The Bi@C nanospheres with a core-shell structure are beneficial to shortening the transmission path of electrons/ions and reducing the risk from structural rupture of the particles during cycling. In addition, the combination of Bi@C nanospheres and porous GR could greatly improve the conductivity and prevent the aggregation of particles, which is conducive to better cycling stability and rate performance. Consequently, Bi@C@GR-2 presents a superior reversible capacity for sodium storage (300 mAh g-1 over 80 cycles) and potassium storage (200 mAh g-1 over 70 cycles) at 0.1 A g-1. Furthermore, in situ electrochemical impedance spectroscopy and ex situ transmission electron microscopy are carried out to analyze and reflect the kinetic reaction mechanism and the phase change of the Bi@C@GR-2 electrode during the charge/discharge processes.

P04.19 A combined use of a G-quadruplex oligonucleotide (GQ) and neuro-inducing small molecules inhibit glioblastoma cell proliferation

Abstract BACKGROUND According to one of the theories, gliomas can occur as a result of dysregulation of stem cell division in the subventricular region of the brain. The CD133 membrane marker is a characteristic of both normal and tumor neural stem cells therefore it can be used to isolate a stem cell population from tumor tissue. Tumor cells actively proliferate which suggests that their possible differentiation may be achieved by inhibiting of their division as these two processes are mutually exclusive. For this purpose, G-quadruplex oligonucleotides together with neural-inducers such as a brain-derived neurotrophic factor (BDNF) may be used. MATERIAL AND METHODS Five cell cultures obtained from human glioblastoma tissues were analyzed for expression of CD133 using RT-qPCR. From cell culture with the highest level of CD133 using immunomagnetic separation CD133+ and CD133- cultures were received. CD133fr/peGFP-c1 recombinant DNA consisted of a CD133 second extracellular loop fragment and a peGFP-c1 vector was constructed to determine the localization of prominin-1, that is known as CD133 when found on cell membrane, using confocal microscopy. On chosen cell cultures an oligonucleotide bi-(AID-1-T) and its combination with BDNF were tested. The mechanism of GQ’s action is cytostatic and its non-toxicity properties were proved by flow cytometry. For evaluating the proliferative activity of cells MTT assay was performed on 10th and 20th days after exposure to the factors. RESULTS Cell culture G01 was chosen for further research as it had the highest level of the CD133. Colocalization of CD133 and GFP demonstrated a membrane localization of CD133 in cells with high expression level of this marker. MTT assay on 10th day after exposure to bi-(AID-1-T) as well as its combination with BDNF on cell culture G01 CD133- showed total inhibition of cell proliferation. The same combinations tested on G01 CD133+ cell culture demonstrated no difference in proliferative activity. After 20 days after exposure to bi-(AID-1-T) and combination of bi-(AID-1-T) with BDNF the significant decrease of G01 CD133+ cells’ proliferation was observed. When tested on whole glioblastoma cell culture G01 these combinations also showed significant inhibition of cell proliferation. CONCLUSION We showed that glioblastoma cells upon transfection with recombinant DNA, that contains a fragment of CD133, mainly have a membrane localization of this marker. It was observed that CD133+ cells are more stable to external influence that can be a proof of the fact that CD133 is charactered for glioblastoma stem cells. We tested the effect of an GQ bi-(AID-1-T) and its combination with BDNF and showed that BDNF is necessary for blocking proliferation of glioblastoma cells. Altogether, the results may be used for further research as it reveals a potential treatment for patients with glioblastoma. Grant №075-15-2020-809 (13.1902.21.0030).

A Chatt-Type Catalyst with One Coordination Site for Dinitrogen Reduction to Ammonia.

With [Mo(N2)(P2 MePP2 Ph)] the first Chatt‐type complex with one coordination site catalytically converting N2 to ammonia is presented. Employing SmI2 as reductant and H2O as proton source 26 equivalents of ammonia are generated. Analogous Mo0‐N2 complexes supported by a combination of bi‐ and tridentate phosphine ligands are catalytically inactive under the same conditions. These findings are interpreted by analyzing structural and spectroscopic features of the employed systems, leading to the conclusion that the catalytic activity of the title complex is due to the strong activation of N2 and the unique topology of the pentadentate tetrapodal (pentaPod) ligand P2 MePP2 Ph. The analogous hydrazido(2‐) complex [Mo(NNH2)(P2 MePP2 Ph)](BArF)2 is generated by protonation with HBArF in ether and characterized by NMR and vibrational spectroscopy. Importantly, it is shown to be catalytically active as well. Along with the fact that the structure of the title complex precludes dimerization this demonstrates that the corresponding catalytic cycle follows a mononuclear pathway. The implications of a PCET mechanism on this reactive scheme are considered.

Novel in situ Bi−Sb‐Film Electrodes for Trace Heavy Metal Analysis

AbstractThis work reports on new in situ formed Bi−Sb‐film glassy carbon electrodes (Bi−SbFEs) with different Bi(III):Sb(III) mass concentration ratios (1 : 9, 2 : 8, 3 : 7, 4 : 6, 5 : 5, 6 : 4, 7 : 3, 8 : 2, 9 : 1) and at two different total mass concentrations of Bi(III) and Sb(III), i. e. 0.5 and 1.0 mg/L. The analytical performance of these Bi−SbFEs was compared with Bi‐film (BiFE) and Sb‐film (SbFE) electrodes in 0.1 M acetate buffer solution. All combinations of Bi−SbFEs were selective for Zn(II), Cd(II), and Pb(II) detection. Bi−SbFEs showed linear concentration ranges for Zn(II), Cd(II), and Pb(II) substantially wider than that for BiFE. Moreover, the method's sensitivities can be substantially improved by using different Bi−SbFEs compared with BiFE and SbFE. Most of the Bi−SbFE methods provided satisfactory recovery for Cd(II) determination, many of them also for Pb(II), whereas for Zn(II) only a few methods provided recovery values within the 80.0–120.0 % recovery range. The precision of different Bi−SbFEs were satisfactory for Pb(II) and Cd(II) with an RSD lower than 20.0 %. Accumulation time optimisation resulted in lower LOD and LOQ, higher sensitivity. Finally, electrochemical impedance spectroscopy was employed for the first time to characterise the electroanalytical behaviour of an SbFE. The latter analysis was employed to compare the electrode's properties with pure BiFE and pure GCE, and to show when the system is under a kinetic‐ and/or diffusion‐controlled process.

The Cytotoxic and Antimigratory Activity of Brazilin-Doxorubicin on MCF-7/HER2 Cells.

Purpose: Breast cancer cells with overexpression of HER2 are known to be more aggressive, invasive, and resistant to chemotherapeutic agent. Brazilin, the major compound in the Caesalpinia sappan L. (CS) heartwood, has been studied for it's anticancer activity. The purpose of this study was to investigate the cytotoxic and antimigratory activity of brazilin (Bi) in combination with doxorubicin (Dox) on MCF-7/HER2 cells.Methods: Cytotoxic activities of Bi individually and in combination with Dox were examined by MTT assay. Synergistic effects were analyzed by combination index (CI). Apoptosis and cell cycle profiles were observed by using flow cytometry. Migrating and invading cells were observed by using a Boyden chamber assay. Levels of MMP2 and MMP9 activity were observed by using a gelatin zymography assay. Levels of HER2, Bcl-2, Rac1, and p120 protein expression were observed by using an immunoblotting assay.Results: The results of the MTT assay showed that Bi inhibited MCF-7/HER2 cell growth in a dose-dependent manner with an IC50 of 54 ± 3.7 µM. Furthermore, the combination of Bi and Dox showed a synergistic effect (CI <1). Flow cytometric analysis of Bi and its combination with Dox showed cellular accumulation in the G2/M phase and induction of apoptosis through suppression of Bcl-2 protein expression. In the Boyden chamber assay, gelatin zymography, and subsequent immunoblotting assay, the combination Bi and Dox inhibited migration, possibly through downregulation of MMP9, MMP2, HER2, Rac1, and p120 protein expression.Conclusion: We conclude that Bi enhanced cytotoxic activity of Dox and inhibited migration of MCF-7/HER2 cells. Therefore, we believe that it has strong potential to be developed for the treatment of metastatic breast cancer with HER2 overexpression.

Actinide–Pnictide (An−Pn) Bonds Spanning Non‐Metal, Metalloid, and Metal Combinations (An=U, Th; Pn=P, As, Sb, Bi)

AbstractThe synthesis and characterisation is presented of the compounds [An(TrenDMBS){Pn(SiMe3)2}] and [An(TrenTIPS){Pn(SiMe3)2}] [TrenDMBS=N(CH2CH2NSiMe2But)3, An=U, Pn=P, As, Sb, Bi; An=Th, Pn=P, As; TrenTIPS=N(CH2CH2NSiPri3)3, An=U, Pn=P, As, Sb; An=Th, Pn=P, As, Sb]. The U−Sb and Th−Sb moieties are unprecedented examples of any kind of An−Sb molecular bond, and the U−Bi bond is the first two‐centre‐two‐electron (2c–2e) one. The Th−Bi combination was too unstable to isolate, underscoring the fragility of these linkages. However, the U−Bi complex is the heaviest 2c–2e pairing of two elements involving an actinide on a macroscopic scale under ambient conditions, and this is exceeded only by An−An pairings prepared under cryogenic matrix isolation conditions. Thermolysis and photolysis experiments suggest that the U−Pn bonds degrade by homolytic bond cleavage, whereas the more redox‐robust thorium compounds engage in an acid–base/dehydrocoupling route.

Actinide-Pnictide (An-Pn) Bonds Spanning Non-Metal, Metalloid, and Metal Combinations (An=U, Th; Pn=P, As, Sb, Bi).

The synthesis and characterisation is presented of the compounds [An(TrenDMBS){Pn(SiMe3)2}] and [An(TrenTIPS){Pn(SiMe3)2}] [TrenDMBS=N(CH2CH2NSiMe2But)3, An=U, Pn=P, As, Sb, Bi; An=Th, Pn=P, As; TrenTIPS=N(CH2CH2NSiPri 3)3, An=U, Pn=P, As, Sb; An=Th, Pn=P, As, Sb]. The U−Sb and Th−Sb moieties are unprecedented examples of any kind of An−Sb molecular bond, and the U−Bi bond is the first two‐centre‐two‐electron (2c–2e) one. The Th−Bi combination was too unstable to isolate, underscoring the fragility of these linkages. However, the U−Bi complex is the heaviest 2c–2e pairing of two elements involving an actinide on a macroscopic scale under ambient conditions, and this is exceeded only by An−An pairings prepared under cryogenic matrix isolation conditions. Thermolysis and photolysis experiments suggest that the U−Pn bonds degrade by homolytic bond cleavage, whereas the more redox‐robust thorium compounds engage in an acid–base/dehydrocoupling route.

Computational and Spectroscopic Analysis of Ion Interactions in Sodium and Lithium Ion Battery Electrolytes

Rising interests in sodium ion batteries as low-cost alternatives to lithium ion batteries necessitates a closer look at the interactions between the sodium ion and its anion in electrolyte solution. As demonstrated in lithium ion batteries, solvent and anion species involved in solvation of the lithium ion contribute to the nucleation and growth of the solid electrolyte interphase of the anode. The same is true of sodium ion batteries, which parallel lithium ion batteries in their use of carbonate-based organic solvents and the hexafluorophosphate (PF6 -) anion. Infrared spectroscopy (FTIR) was used to probe the interaction between PF6 - and sodium in various carbonate-based solvent, and these measurements were interpreted using predictions made by density functional theory (DFT) calculations on the model LiPF6 and NaPF6-based solvates. In addition, molecular dynamics (MD) simulations were performed on the EC:DMC/LiPF6 and EC:DMC/NaPF6 electrolytes. A revised many-body polarizable APPLE&P force field was used in MD simulations. Solvate structures extracted from MD simulations were found in good agreement with interpretations of FTIR spectra. Specifically, initial MD results supported our previous finding indicating that the Li+ and Na+ solvation numbers from Raman measurements are found are similar in linear carbonates. Moreover, MD simulations predicted that the PF6 - anion coordination to Li+ and Na+ are quite different. Mono-dentate LiPF6 binding prevailing in LiPF6-DMC, and a combination of bi- and tri-dentate binding dominating in NaPF6-DMC in agreement with the free energies of solvates estimated from DFT cluster – continuum calculations. MD simulations also predicted solvent, anion, Li and Na self-diffusion coefficients in excellent agreement with pfg-NMR measurements.

A soluble guanylate cyclase activator protects from diabetic nephropathy beyond standard of care in the ZSF1 rat

The pathogenesis of diabetic nephropathy is associated with abnormalities of renal nitric oxide generation and signaling. We evaluated the effect of BI 684067, a soluble guanylate cyclase (sGC) activator, in combination with the current standard of care (SoC), on the progression of diabetic nephropathy. Male ZSF1 rats were administered enalapril (3 mg/kg in drinking water) for 10 days, after which they were randomized to either continue to receive enalapril alone or the combination of enalapril and one of three doses of BI 684067 (20, 40 and 80 mg/kg) in chow for 10 weeks. Weekly urinary protein to creatinine ratio (UPCR) as well as daily mean arterial pressure (MAP) and heart rate (HR) were measured. At study end, kidneys were assessed for glomerular lesions and α-SMA expression, a marker of myofibroblast activation. The combination of BI 684067 and enalapril resulted in significant dose-dependent decreases of the following when compared to enalapril alone: UPCR (BI 684067 at 20, 40, and 80 mg/kg : 27, 39, 48% reductions respectively), incidence of glomerulosclerosis (BI 684067 at 20, 40, and 80 mg/kg: 29, 32, 44% reductions, respectively) and α-SMA expression (BI 684067at 20, 40, and 80 mg/kg : 26, 40, 42% reductions, respectively). The MAP was significantly reduced by BI 684067 in combination with enalapril (- 3 mm Hg vs enalapril alone at the doses of 40 and 80 mg/kg), however there was no significant effect on HR. These results support the efficacy of an sGC activator in preventing the progression of diabetic nephropathy when combined with the SoC.

Hierarchical Bi based nanobundles: An excellent photocatalyst for visible-light degradation of Rhodamine B dye

Hierarchical Bi based nanobundles were self-assembled via an aqueous reduction approach using hydrazine hydrate as reductive agent, and were used as photocatalysts for the degradation of Rhodamine B (RhB) under visible light. PVP molecules were designed as inducing agent to construct the Bi based nanobundles. The as-obtained samples were characterized by X-ray diffraction (XRD), energy dispersive X-ray (EDX), thermogravimetric–differential thermal analyzer (TG–DTA), infrared spectroscopy (IR) and field emission scanning electron microscopy (FESEM) to get clear information of the crystals. A possible formation mechanism for the interesting architectures was proposed in the paper. The Bi based nanobundles exhibited excellent photocatalytic activity and good cycling performance towards photodegradation of RhB under visible light. The pH-sensitive degradation can reach 96% in degradation rate after 90min, which indicates potential applications of the Bi based nanobundles on the degradation of organic pollutants. Degradation mechanism is proposed on the combination of Bi and BiOCl crystals.

Double-Doping Approach to Enhancing the Thermoelectric Figure-of-Merit of n-Type Mg2Si Synthesized by Use of Spark Plasma Sintering

We report significant enhancement of the thermoelectric figure-of-merit of Mg2Si by double-doping with a combination of Bi, Pb, and Sb as doping elements. Addition of any two of these three elements to Mg2Si increases the electrical conductivity by more than three orders of magnitude at 323 K, irrespective of the doping elements used. However, a corresponding decrease in the Seebeck coefficient is observed in comparison with undoped Mg2Si. Irrespective of the combination of the three elements used for double doping, a figure-of-merit of approximately 0.7 at 873 K is obtained for Mg2Si; this is primarily because of enhancement of the electrical conductivity.

Origin of silica and fingerprinting of Australian sedimentary opals

Opal is Australia's national gemstone with a significant fraction of the global supply mined from highly weathered Cretaceous sedimentary rocks within the Great Artesian Basin. Surprisingly, relatively little is known about the petrography and trace elemental composition of opal and its host rocks and consequently about the source of silica that underpins its formation. Using laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS) of precious and common opal from key opal mining areas in the Great Artesian Basin coupled with multivariate analyses of 59 detectable elements in opal, we show that a mining region from which an opal originates can be constrained by using a combination of Hf, Ba, Zr and Gd with a high degree of confidence. Likewise, precious opal can be distinguished from common (non-precious opal) using a combination of Bi, Ta, Sn and Ca as these particular elements are especially low in concentration in precious opal. Although the opal from the Great Artesian Basin is sedimentary, the Ba content of opals from the eastern part of the basin suggests a volcanic origin. The most likely source of Ba and hence of silica for these opals are feldspars, now altered to kaolinite, sourced as volcaniclastic sediment from the Cretaceous Whitsunday Volcanic Province that marked the rifting and breakup of eastern Gondwana. The alteration of detrital feldspars to kaolinite and their replacement by void-filling opal confirms that weathering has played a critical role in the formation of Australian opal. The opal host rocks are severely weathered with a chemical index of alteration (CIA) up to 92. For the majority of opals studied, the silica is most likely derived locally from the opal host rocks, which impart a unique elemental signature on the opal at any particular locality. Mintabie opal, however, has very low Zr/Hf ratio, which is decoupled from its host rock, suggesting that the silica source is different from all the other opals, or that the silica fluid has experienced intense trace element fractionation, or both. The combination of analytical and statistical methods used here provides a powerful tool for a wide range of provenance studies, not just gemstones, where relationships between a large number of major and trace elements are difficult to unravel.

MOCVD of C‐oriented Bi2Te3 Films on SiO2 Substrates using Triethyl Bismuth and Di‐tertiarybutyl Tellurium

AbstractMetal‐organic (MO)CVD of bismuth telluride thin films is investigated by using a combination of optimized bismuth and tellurium precursors along with H2 as a reactant gas. Good quality films are obtained, even at 300 °C. The Bi precursors are trimethyl bismuth (Bi(CH3)3, Bi(Me3)) and triethyl bismuth (Bi(C2H5)3, Bi(Et)3), and the Te precursors are diethyl tellurium (Te(C2H5)2, Te(Et)2), di‐isopropyl tellurium (Te(C3H7)2, Te(iPr)2), and di‐tertiarybutyl tellurium (Te(C4H9)2, Te(tBu)2). The integrated absorbance area of C‐H stretching vibrations in the range 2800–3200 cm−1 is estimated to determine the decomposition rate of the Bi and Te precursors. C‐oriented Bi2Te3 films are obtained at 300 °C and under 2.5 Torr using Bi(Et)3 and Te(tBu)2 and characterized. Further, the microstructure, crystallinity, and surface morphology of the films are determined. The appropriate stoichiometry of the bismuth telluride films is obtained as Bi/Te = 2:3. The combination of Bi(Et)3 and Te(tBu)2 is the most effective for low‐temperature deposition because, compared to the other precursors, the decomposition of these precursors starts at a lower temperature. Investigations of the precursor decomposition behavior show that the absorbance of C‐H stretching vibrations of ligands in precursors in the gas phase is sensitive to the analysis conditions.

EVALUATION OF METALORGANIC PRECURSORS FOR PREPARING BiFeO3 THIN FILMS BY LIQUID DELIVERY CHEMICAL VAPOR DEPOSITION

ABSTRACT The metalorganic precursors to fabricate multiferroic BiFeO3 thin films by liquid-delivery metalorganic chemical vapor deposition were investigated. Among the evaluated compounds, the combinations of Bi(p-Tol)3 and iron β -diketonates were suitable to control the metal composition in BiFeO3 films. The films obtained using the precursor solution with the molar ratio of Bi:Fe = 1:1 included excess bismuth. The films with only BiFeO3 phase could be fabricated at the substrate temperatures of 500°C and 525°C by using the precursor solution of Bi(p-Tol)3 and Fe(IBPM)3 with the molar ratio of 2:1. Though the remnant polarization of the film obtained at 525°C was very small, it was confirmed that the BiFeO3 film had ferroelectricity.