Carbonate Hydrate Research Articles

Calcium isotope evidence for subduction-enriched lithospheric mantle under the northern North China Craton

The stable isotopes of calcium have tremendous potential for constraining the evolution of the mantle as well as fingerprinting the recycling of carbon in the mantle via subduction. In order to better identify possible contributions of subducted carbonate-bearing materials to upper mantle heterogeneity, we present Ca isotope data for peridotite xenoliths from Fanshi, northern North China Craton. These peridotites have previously been studied for major and trace element, Sr-Nd isotopic compositions. Two metasomatic events in the lithosphere mantle caused by subduction of carbonated sediments from the Pale-Asian oceanic slab, were previously identified: the first by carbonatite melt and the second by carbonate-rich silicate melt. δ44/40Ca (=((44Ca/40Ca)SAMPLE/(44Ca/40Ca)SRM915a − 1) × 1000) of clinopyroxenes (Cpx) in the Fanshi peridotites varies from +0.84‰ to +1.17‰ and δ44/40Ca of orthopyroxenes (Opx) from +0.82‰ to +1.22‰. δ44/40Ca of the clinopyroxenes show a larger variation than that could be attributed to partial melting and display positive and negative trends with (La/Yb)N and Ti/Eu, respectively, suggesting the effect of two distinct metasomatic events. A harzburgite, modified only by the early carbonatite metasomatism, has the highest δ44/40Ca (+1.17‰). The lherzolites affected by the second metasomatic melt show lower Δ44/40CaOpx-Cpx (=δ44/40CaOpx − δ44/40CaCpx, −0.11‰ to 0‰) than the un-metasomatized lherzolites (+0.11‰ to +0.24‰), implying that the second metasomatism triggered Ca isotope disequilibrium between the clinopyroxene and co-existing orthopyroxene. This is consistent with positive trends between δ44/40Ca and 87Sr/86Sr, (La/Yb)N in the clinopyroxenes of the lherzolites, indicating that the second metasomatism also resulted in high δ44/40Ca in the clinopyroxenes of the lherzolites (up to +1.09‰). Furthermore, the harzburgites and lherzolites converge toward the second metasomatic event in diagrams of 87Sr/86Sr versus δ44/40Ca, suggesting an extensive effect of the second metasomatism. The heavy Ca isotope signature in these metasomatic clinopyroxenes applies to both first carbonatite melt and second carbonate-rich silicate melt derived from carbonated sediments (>+1.17‰ and ∼+1.09‰, respectively). However, heavy Ca isotope composition is inconsistent with low δ44/40Ca in carbonated sediments from the Paleo-Asian ocean, but could be the characteristic of an evolved sediment-derived hydrous carbonate melt. This implies significant Ca isotope fractionation during subduction of carbonated sediments. While currently there is plenty of debate regarding the exact significance of Ca isotope heterogeneity in mantle rocks, our results show at a minimum that Ca isotopes are rather heterogeneous in supra-subduction mantle rocks and could be used to deciphering mantle metasomatic models and detecting recycled crustal materials.

Effect of Sucroferric Oxyhydroxide on Fibroblast Growth Factor 23 Levels in Hemodialysis Patients

Objective: This study investigated the effects of sucroferric oxyhydroxide on fibroblast growth factor (FGF)-23 and dose reduction of erythropoiesis-stimulating agents (ESA) and intravenous saccharated ferric oxide in hemodialysis patients. Methods: In this prospective, open-label, parallel-group, multicenter trial involving patients receiving lanthanum carbonate hydrate, eligible patients were randomized to a sucroferric oxyhydroxide group or a control group. Hemoglobin, serum phosphate, FGF-23, iron, and ferritin levels, as well as transferrin saturation, doses of intravenous saccharated ferric oxide and ESA administered, and the erythropoietin responsiveness index (ERI) were monitored for 24 weeks. Results: Sixty-eight eligible patients were allocated to receive sucroferric oxyhydroxide (n = 34) or serve as controls (n = 34). Data for 31 patients in the sucroferric oxyhydroxide group and 32 in the control group were analyzed. Serum phosphate was equally well controlled in both groups. In the sucroferric oxyhydroxide group, intact FGF-23 levels decreased significantly from baseline at the end of the study (p = 0.01) and there was a significant difference compared with the control group (p = 0.035). Required doses of ESA and ERI were significantly reduced in the sucroferric oxyhydroxide group decreased significantly. The dose of intravenous saccharated ferric oxide required in the sucroferric oxyhydroxide group was significantly lower than that at baseline (p = 0.006) and in the control group (p = 0.003). Conclusions: Treatment of hyperphosphatemia with sucroferric oxyhydroxide was effective in patients on hemodialysis, resulting in decreased serum FGF-23 levels and a reduction in the required dose of saccharated ferric oxide.

Evaluation of the effect of lanthanum carbonate hydrate on the pharmacokinetics of roxadustat in non‐elderly healthy adult male subjects

Roxadustat is a hypoxia-inducible factor prolyl hydroxylase inhibitor currently being investigated for the treatment of anemia in chronic kidney disease. Lanthanum carbonate is a phosphate binder that is commonly used to treat hyperphosphatemia in patients with chronic kidney disease. This study investigated the effect of lanthanum carbonate on the pharmacokinetics, safety and tolerability of a single oral dose of roxadustat in healthy non-elderly adult male subjects. This was an open-label, randomized, two-period, two-sequence crossover study in non-elderly healthy adult males. Subjects randomized to Group 1 received roxadustat alone during Period 1 and roxadustat concomitantly with lanthanum carbonate during Period 2; subjects randomized to Group 2 received roxadustat concomitantly with lanthanum carbonate during Period 1 and roxadustat alone during Period 2. All subjects received a single oral dose of 100mg roxadustat on Day 1 in both periods. Subjects receiving concomitant lanthanum carbonate received 750mg lanthanum carbonate three times daily on Days 1 and 2. Pharmacokinetic assessments were conducted on Days 1-4 in both periods. The primary study outcomes were the area under the concentration-time curve from the time of dosing extrapolated to infinity (AUCinf ), and maximum concentration (Cmax ); the geometric least squares mean ratio (GMR; roxadustat+lanthanum carbonate/roxadustat alone) and corresponding 90% confidence interval (CI) was calculated for AUCinf and Cmax . Safety was assessed by the occurrence of treatment-emergent adverse events (TEAEs), laboratory test results, vital signs and standard 12-lead electrocardiogram. A total of 18 subjects were enrolled (Group 1, n=9; Group 2, n=9); no subjects discontinued from the study. Roxadustat was rapidly absorbed, reaching maximum plasma concentration between 1 and 4hours. The GMRs for AUCinf and Cmax were 88.00% (90% CI: 84.01, 92.17) and 98.58% (90% CI: 92.92, 104.58), respectively. The 90% CIs for both parameters were within the no-effect boundaries of 80% and 125%, indicating a lack of effect of lanthanum carbonate on roxadustat absorption. No deaths or serious TEAEs occurred. Concomitant administration of a single oral dose of 100mg roxadustat and 750mg lanthanum carbonate three times daily did not impact the AUCinf or Cmax of roxadustat and was considered safe and well tolerated in non-elderly healthy adult male Japanese subjects.

Control of Water Chemistry in Alkaline Lakes: Solubility of Monohydrocalcite and Amorphous Magnesium Carbonate in CaCl2–MgCl2–Na2CO3 Solutions

Alkaline lakes play an important role in the global carbon cycle. Nevertheless, little is known about the chemical processes related to sequestration of CO2 in these lakes. Our earlier study demonstrated that the formation of monohydrocalcite (MHC), a hydrous carbonate mineral frequently found in alkaline lakes, requires coexistence of amorphous Mg carbonate (AMC). It is therefore possible that MHC and AMC control the water chemistries of alkaline lakes. To test this hypothesis, we measured the solubilities of MHC and AMC in Na2CO3–MgCl2–CaCl2 solutions and compared them with the water chemistries of alkaline lakes. Results showed that the solubility of MHC is independent of the Mg contents of the system. The solubility product of AMC was almost 2 orders of magnitude higher than that of MHC. The water chemistries obtained from the alkaline saline lakes with pH > 9 around the world closely approximated saturation with respect to both MHC and AMC. MHC, which is a metastable phase, transforms quickly to arag...

Effects of pressure and water on electrical conductivity of carbonate melt with implications for conductivity anomaly in continental mantle lithosphere

The electrical conductivity of Na, Mg-bearing carbonate melts was measured in a Kawai-type multi-anvil apparatus as a function of pressure. The carbonate samples were mixtures of MgCO3 and Na2CO3 or Mg5(CO3)4(OH)2·4(H2O) and Na2CO3. High-pressure experiments on the carbonate systems were performed up to 1800 K in a wide pressure range from 3.4 to 10.9 GPa. The sample conductivity abruptly changed at the eutectic temperature, which increased with increasing pressure. The hydrous carbonate yielded a lower eutectic temperature than the anhydrous carbonate and showed weaker pressure dependence. The molten state carbonates showed very high electrical conductivity with temperature dependence following the Arrhenius law. As the pressure increased, the conductivity decreased. The negative pressure dependence of the electrical conductivity of the hydrous carbonate melt was larger than that of the anhydrous one. The activation volumes were ΔV = 1.81 and 3.61 cm mol−1 for the anhydrous and hydrous carbonate melts, respectively. The high electrical conductivity observed in the mantle beneath the Slave and Brazilian cratons can be explained by the process of lithospheric rejuvenation due to a small amount of hydrous carbonated melt released from the crystallization of the kimberlitic magma at the base of the continental mantle lithosphere.

Isotopic signatures of REY mineralization associated with lignite basins in South Primorye, Russian Far East

The paper is based on stable isotopic analyses (C, O, H) first obtained for the rare earth elements + yttrium mineralization of South Primorye and Southwest Japan in addition to recent exploration data and some K-Ar and U-Pb datings. The analyzed minerals include hydrous carbonates and clay minerals that are hosted by argillized (weathered) shale, granite, mafic rocks, and semi-lithified sediments of various (from Cambrian to Late Cenozoic) age. The data distinctly evidence that a major agent of rare metal leaching from the host rocks and their redistribution inside the lignite-bearing sediments and weathered crust was meteoric water. Its moderately acidic character was due to carbon dioxide flowing up from the mantle through faults associated with the lignite basins, in addition to organic matter and sulfides disseminated in the host rocks. Concentrated precipitation and sorption of rare earths and yttrium from the evolved meteoric water were probably caused by their neutralization or even alkalization that had resulted from CO2 release near the surface. The previous Sr-Nd isotopic data for lanthanite-(Nd) from South Primorye indicate the upper Earth’s crust origin of the ore metals. Thus, both endo- and exogenous factors significantly influenced the studied mineralization in Primorye. Juvenile CO2 made a key contribution to meteoric waters allowing them to mobilize and redistribute ore components in the near-surface conditions. The deep-seated faults cross-cutting and bordering the lignite basins and providing the necessary conduits for the upflows of carbon dioxide are suggested to control localization of the studied mineralization.

Enhancement of CO Evolution by Modification of Ga2O3 with Rare-Earth Elements for the Photocatalytic Conversion of CO2 by H2O.

Modification of the surface of Ga2O3 with rare-earth elements enhanced the evolution of CO as a reduction product in the photocatalytic conversion of CO2 using H2O as an electron donor under UV irradiation in aqueous NaHCO3 as a pH buffer, with the rare-earth species functioning as a CO2 capture and storage material. Isotope experiments using 13CO2 as a substrate clearly revealed that CO was generated from the introduced gaseous CO2. In the presence of the NaHCO3 additive, the rare-earth (RE) species on the Ga2O3 surface are transformed into carbonate hydrates (RE2(CO3)3·nH2O) and/or hydroxycarbonates (RE2(OH)2(3-x)(CO3)x) which are decomposed upon photoirradiation. Consequently, Ag-loaded Yb-modified Ga2O3 exhibits much higher activity (209 μmol h-1 of CO) than the pristine Ag-loaded Ga2O3. The further modification of the surface of the Yb-modified Ga2O3 with Zn afforded a selectivity toward CO evolution of 80%. Thus, we successfully achieved an efficient Ag-loaded Yb- and Zn-modified Ga2O3 photocatalyst with high activity and controllable selectivity, suitable for use in artificial photosynthesis.

Nanoceria synthesis in molten KOH-NaOH mixture: Characterization and oxygen vacancy formation

Nanoceria was synthesized by treating cerium carbonate hydrate in a molten KOH-NaOH mixture at 200°C. The nanoceria thus synthesized under a hydrogen atmosphere had a crystal size of 21.6nm measured by XRD, consistent with the particle size of 23nm measured by TEM. Raman spectra results indicated that the nanoceria produced under hydrogen had a downshift of 0.9cm−1 from the sample synthesized in air. XPS spectra showed that the Ce3+ fraction of the nanoceria synthesized in hydrogen was greater than that produced in air. The oxygen vacancies were formed by partial oxidization of the precursor in molten KOH-NaOH mixture. The UV–visible absorption properties of ceria synthesized under hydrogen showed a 34nm red-shift compared with that synthesized in air. The nanoceria prepared in this work had a better catalytic property for CO oxidization than the commercial nanoceria. Results indicated that the increased Ce3+ fraction or oxygen vacancies formed by this partial oxidization process extended the absorption edge of ceria resulting in a narrower band gap, and enhanced the catalytic activity of nanoceria. This method has proven to provide a simple and scalable method for the synthesis of high quality nanoceria.

Multi‐Step Crystallization of Barium Carbonate: Rapid Interconversion of Amorphous and Crystalline Precursors

AbstractThe direct observation of amorphous barium carbonate (ABC), which transforms into a previously unknown barium carbonate hydrate (herewith named gortatowskite) within a few hundred milliseconds of formation, is described. In situ X‐ray scattering, cryo‐, and low‐dose electron microscopy were used to capture the transformation of nanoparticulate ABC into gortatowskite crystals, highly anisotropic sheets that are up to 1 μm in width, yet only about 10 nm in thickness. Recrystallization of gortatowskite to witherite starts within 30 seconds. We describe a bulk synthesis and report a first assessment of the composition, vibrational spectra, and structure of gortatowskite. Our findings indicate that transient amorphous and crystalline precursors can play a role in aqueous precipitation pathways that may often be overlooked owing to their extremely short lifetimes and small dimensions. However, such transient precursors may be integral to the formation of more stable phases.

Multi-Step Crystallization of Barium Carbonate: Rapid Interconversion of Amorphous and Crystalline Precursors.

The direct observation of amorphous barium carbonate (ABC), which transforms into a previously unknown barium carbonate hydrate (herewith named gortatowskite) within a few hundred milliseconds of formation, is described. In situ X-ray scattering, cryo-, and low-dose electron microscopy were used to capture the transformation of nanoparticulate ABC into gortatowskite crystals, highly anisotropic sheets that are up to 1 μm in width, yet only about 10 nm in thickness. Recrystallization of gortatowskite to witherite starts within 30 seconds. We describe a bulk synthesis and report a first assessment of the composition, vibrational spectra, and structure of gortatowskite. Our findings indicate that transient amorphous and crystalline precursors can play a role in aqueous precipitation pathways that may often be overlooked owing to their extremely short lifetimes and small dimensions. However, such transient precursors may be integral to the formation of more stable phases.

MINERALOGICAL AND SPECTROSCOPIC STUDY OF NESQUEHONITE SYNTHESIZED BY REACTION OF GASEOUS CO2 WITH MG CHLORIDE SOLUTION

Nesquehonite, a hydrous carbonate with promising uses such as building raw material and treatment of wastewaters, was synthesized under low pressure conditions by reaction of gaseous CO2 with Mg chloride solution and it was studied by means of X-Ray Diffraction, optical and scanning/transmission electron microscopy, and FTIR and Raman spectroscopic methods. Synthesized nesquehonite forms elongated fibers, exhibiting transparent to translucent diaphaneity and vitreous luster. It is characterized by high crystallinity. IR and Raman spectroscopy indicated the presence of OHand HCO3 - in the crystal structure of nesquehonite. The nesquehonite synthesis described herein constitutes a potential permanent storage of CO2 emissions.

Red upconverted luminescence in controllable self-assembled RE2O3: Yb3+/Er3+ (RE = Gd, Y) 3D nanoflowers

Self-assembled three-dimensional RE2O3: Yb3+/Er3+ (RE = Gd and Y) nanoflowers were synthesized after heating the gadolinium or yttrium carbonate hydrate precursor at high temperature, in which precursors were obtained by a facile co-precipitation process. The precursors and the final products were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and photoluminescence (PL) spectra. The factors those affect the morphology of the final products, including RE-to-urea ratio, pH value of initial solution, reactive temperature and time, were optimized. The formation process of 3D flower-like structure was demonstrated as a time-dependent self-assembly reaction. The up-conversion (UC) spectra of the as-obtained RE2O3: Yb3+/Er3+ (RE = Gd and Y) samples were also discussed as function of morphology, annealing temperature and Yb3+ contents, in which the factors those affect the emitting color or the integrated intensity ratio of red to green were analyzed. High specific surface area and short distance between Yb3+ and Er3+ are conductive to red emission.

Corrosion behavior of low pressure cold sprayed Zn-Ni composite coatings

In this study, Zn-Ni composite coatings with different Ni contents were deposited on low-carbon steel using Low pressure cold spray (LPCS) method. The morphology, element distribution and phase compositions of powders and as-sprayed coatings were analyzed by using scanning electron microscopy, energy dispersive spectrometer and X-ray diffraction respectively. The corrosion protection mechanism of these composite coatings were investigated using electrochemical technique and their corrosion morphologies. The results show that Zn-Ni composite coatings exhibited a better sacrificial anodic protection and physical shielding effect, where the corrosion resistance of the coating with 10 wt% Ni in the feedstock was best. The corrosion products were mainly composed of Zinc hydroxide Zn(OH)2, basic zinc chloride hydrate ZnCl2·4Zn(OH)2·H2O, basic zinc carbonate hydrate Zn4·CO3(OH)6·H2O and the corrosion products is not mixed with alumina. The corrosion process mainly includes active dissolution of zinc, zinc cathodic protection, physical shielding caused by corrosion products.

Stability of phlogopite in ultrapotassic kimberlite-like systems at 5.5–7.5 GPa

Hydrous K-rich kimberlite-like systems are studied experimentally at 5.5–7.5 GPa and 1200–1450 °C in terms of phase relations and conditions for formation and stability of phlogopite. The starting samples are phlogopite–carbonatite–phlogopite sandwiches and harzburgite–carbonatite mixtures consisting of Ol + Grt + Cpx + L (±Opx), according to the previous experimental results obtained at the same P–T parameters but in water-free systems. Carbonatite is represented by a K- and Ca-rich composition that may form at the top of a slab. In the presence of carbonatitic melt, phlogopite can partly melt in a peritectic reaction at 5.5 GPa and 1200–1350 °C, as well as at 6.3–7.0 GPa and 1200 °C: 2Phl + CaCO3 (L)↔Cpx + Ol + Grt + K2CO3 (L) + 2H2O (L). Synthesis of phlogopite at 5.5 GPa and 1200–1350 °C, with an initial mixture of H2O-bearing harzburgite and carbonatite, demonstrates experimentally that equilibrium in this reaction can be shifted from right to left. Therefore, phlogopite can equilibrate with ultrapotassic carbonate–silicate melts in a ≥ 150 °C region between 1200 and 1350 °C at 5.5 GPa. On the other hand, it can exist but cannot nucleate spontaneously and crystallize in the presence of such melts in quite a large pressure range in experiments at 6.3–7.0 GPa and 1200 °C. Thus, phlogopite can result from metasomatism of peridotite at the base of continental lithospheric mantle (CLM) by ultrapotassic carbonatite agents at depths shallower than 180–195 km, which creates a mechanism of water retaining in CLM. Kimberlite formation can begin at 5.5 GPa and 1350 °C in a phlogopite-bearing peridotite source generating a hydrous carbonate–silicate melt with 10–15 wt% SiO2, Ca# from 45 to 60, and high K enrichment. Upon further heating to 1450 °C due to the effect of a mantle plume at the CLM base, phlogopite disappears and a kimberlite-like melt forms with SiO2 to 20 wt% and Ca# = 35–40.

SYNTHESIS, CRYSTAL STRUCTURE AND PHOTOLUMINESCENCE PROPERTIES OF A NEW RARE-EARTH CARBONATE Na3Eu(CO3)(3)6H2O

A new sodium europium carbonate hydrate, Na3Eu(CO3)3·6H2O, has been prepared using the hydrothermal method, and its structure was determined by single crystal X-Ray diffraction analysis for the first time. It crystallizes in the polar hexagonal space group P 63 with a = 11.382(9) A, c = 5.989(5) A, V = 672.06(9) A3, Z = 2, Mr = 509.06, Dc = 2.516 g/cm3, F (000) = 492, μ(MoKα) = 4.84 mm-1, R 1 = 0.015 and wR = 0.038. The structure features a three-dimensional（3D） framework composed of planar (CO3)2- triangles, Eu3+ ions and Na+ ions, which delimits 1D infinite chains with a hexangular star appearance along the c -axis. The IR spectrum and the self-activated photoluminescence properties were studied. Under the excitation of near UV light (395nm), it shows strong red emission at 618 nm with a lifetime of 348.7 μs. Present research indicates that Na3Eu(CO3)3·6H2O is a promising red phosphor for white light-emitting diodes.

Synthesis and characterization of green composites: Focus on accelerated strength, ductility and durability

High strength green composite material has been developed by this project by addition of lime sludge in stabilized class F fly ash with commercial lime and gypsum. The green composite material was shown to have high UCS (unconfined compressive strength) and good California Bearing Ratio (CBR) values to provide sufficient factor of safety as required by the standard code of practice for use in road construction. The good strength is attributed to calcium carbonate in lime sludge, which reacts with pozzolanic products of lime–gypsum stabilized fly ash. X-ray diffraction and scanning electron microscopy have illustrated the interaction/reaction between lime sludge and fly ash and development of additional calcium aluminium oxide carbonate hydrate that has improved the strength of the green composite. The addition of 0.1%, 0.2% and 0.3% (by weight) of short polypropylene (PP) fibre (30 mm size) in the mix has imparted ductility to reduce brittle behaviour. The UCS of 8.1 MPa was achieved with 0.3% fibre in the mix, which is well above the standard requirement. Moreover, durability tests were performed to determine long-term performance. Our overall findings have indicated that the new green composite developed would have good strength, ductility and durability, for construction of flexible pavements. Further research is needed on the long-term field performance for at least one monsoon period before the material can be used with confidence.

مطالعه کانی شناسی و فرآیندهای اسکارنی شدن در اسکارن مس- آهن آوان، شمالخاور خاروانا، شمال باختر ایران

اسکارن مس- آهن آوان در نتیجه نفوذ باتولیت گرانیتوئیدی قره داغ به‌ داخل سنگهای کربناته ناخالص کرتاسه بالایی تشکیل شده است. اسکارن آوان متشکل از پهنه های مرمر، اگزواسکارن و اندواسکارن بوده و بخش اصلی آن پهنه اگزواسکارن، است. بررسیهای کانی شناسی بیانگر آن است که پهنه اگزواسکارن شامل زیرپهنه های گارنت اسکارن، پیروکسن- گارنت اسکارن و کانه اسکارن است. مهمترین کانی کالک سیلیکاته بی آب در پهنه اگزواسکارن، گارنت و ترکیب آن اوگراندیتی (Ad53-89) است. برخی بلورهای گارنت، منطقه‌بندی دارد و ترکیب آنها به طرف حاشیه‌ها به آندرادیت خالص (Ad99) میل می‌کند. کلینوپیروکسن موجود در زیرپهنه پیروکسن- گارنت اسکارن از نوع دیوپسید (Di75-96) است. زیرپهنه کانه اسکارن از کانه‌های مگنتیت، هماتیت، پیریت، کالکوپیریت، بورنیت، مالاکیت و گوتیت تشکیل شده است. وجود میزان محدود ولاستونیت در مجموعه کانی شناسی اسکارن آوان، هم‌رشدی بلورهای گارنت و کلینوپیروکسن و نبود هاله واکنشی بین این دو کانی و نبود بافتهای جانشینی نشان‌دهنده آن است که این کانیها به‌صورت هم‌زمان در محدوده دمایی C°600- 430 و فوگاسیته اکسیژن بیشتر از 10-26 تشکیل شده‌اند.

炭酸ランタン水和物がMRIに及ぼす影響

リンの吸収阻害作用を有する炭酸ランタン水和物は, 腸間膜リンパ節や胃粘膜, 骨への沈着の報告がある. ランタンは磁気共鳴画像 (MRI) の主な造影剤である常磁性金属のガドリニウムと同じランタノイド族であるが, MRIに及ぼす影響については完全に明らかにされていない. 1.5 Tと3.0 TのMRIにおいて, 0, 0.001, 0.003, 0.01, 0.03, 0.1, 0.3および1.0mol/Lの炭酸ランタン水和物を, スピンエコー法とグラディエントエコー法を使用して撮像した. 取得したMRIのアーチファクトを評価するとともに, 1/T1, 1/T2, 1/T2*を求めた. 炭酸ランタン水和物によるアーチファクトは, すべての実験条件において認められなかった. 1.5 T, 3.0 Tともに炭酸ランタン水和物濃度は1/T2, 1/T2*に相関したが (p<0.05), 1/T1の違いはわずかであった. 炭酸ランタン水和物によってT2およびT2*が短縮するため, 一定濃度以上になれば信号強度を低下させるがT1に影響しない.

Hydrophilic, mesoporous structural ZnO nanospheres for pH-triggered release of drug

Mesoporous ZnO nanospheres with average diameter of ~150nm and good hydrophily were successfully synthesized via decomposition of precursor zinc hydroxide carbonate hydrate (ZHCH) by thermal treatment with solvent diethylene glycol (DEG) in the presence of polyvinyl pyrrolidone (PVP). The results reveal that the ZHCH precursor decomposed into small ZnO nanocrystals (~20nm) after being thermal treatment, and these small ZnO nanocrystals self-assembled to spherical mesoporous ZnO aggregates. The obtained ZnO nanospheres exhibited a large specific surface area (43.4m2/g), uniform pore size (6.2nm) and good dispersibility in water. Doxorubicin hydrochloride (DOX) was selected as a model drug to evaluate its release behavior from the mesoporous ZnO nanocarrier. The in vitro drug release experimental results demonstrate that the mesoporous ZnO nanospheres exhibit a pH-triggered release for DOX.

Carbon mineral ecology: Predicting the undiscovered minerals of carbon

Studies in mineral ecology exploit mineralogical databases to document diversity-distribution relationships of minerals—relationships that are integral to characterizing “Earth-like” planets. As carbon is the most crucial element to life on Earth, as well as one of the defining constituents of a planet’s near-surface mineralogy, we focus here on the diversity and distribution of carbon-bearing minerals. We applied a Large Number of Rare Events (LNRE) model to the 403 known minerals of carbon, using 82 922 mineral species/locality data tabulated in http://mindat.org (as of 1 January 2015). We find that all carbon-bearing minerals, as well as subsets containing C with O, H, Ca, or Na, conform to LNRE distributions. Our model predicts that at least 548 C minerals exist on Earth today, indicating that at least 145 carbon-bearing mineral species have yet to be discovered. Furthermore, by analyzing subsets of the most common additional elements in carbon-bearing minerals (i.e., 378 C + O species; 282 C + H species; 133 C + Ca species; and 100 C + Na species), we predict that approximately 129 of these missing carbon minerals contain oxygen, 118 contain hydrogen, 52 contain calcium, and more than 60 contain sodium. The majority of these as yet undescribed minerals are predicted to be hydrous carbonates, many of which may have been overlooked because they are colorless, poorly crystalized, and/or water-soluble. We tabulate 432 chemical formulas of plausible as yet undiscovered carbon minerals, some of which will be natural examples of known synthetic compounds, including carbides such as calcium carbide (CaC 2 ), crystalline hydrocarbons such as pyrene (C 16 H 10 ), and numerous oxalates, formates, anhydrous carbonates, and hydrous carbonates. Many other missing carbon minerals will be isomorphs of known carbon minerals, notably of the more than 100 different hydrous carbonate structures. Surveys of mineral localities with the greatest diversity of carbon minerals, coupled with information on varied C mineral occurrences, point to promising locations for the discovery of as yet undescribed minerals.