多面体镧铈铽氧化物荧光粉的制备研究

采用共沉淀-焙烧法制备镧铈铽氧化物绿色荧光粉,研究了表面助剂、酸碱度、底液溶剂及反应温度对镧铈铽氧化物形貌的影响.用X衍射、扫描电镜以及光学显微镜对产物进行分析表征.结果表明,前驱体镧铈铽草酸盐的结晶环境对镧铈铽氧化物的形貌有着重要影响;在非离子表面助剂、强酸性和有机溶剂做底液的体系环境中更利于得到分散性好、形貌规则、球形度较高的多面体镧铈铽氧化物.     

纳米LaPO4:Ce,Tb的明胶网格沉淀法制备及发光研究

采用明胶网格沉淀法,成功制备了共掺铈、铽的磷酸镧纳米颗粒.用透射电子显微镜、X射线衍射仪及TG对产物的形貌、结构和热稳定性进行了表征.并研究了铈、铽含量,煅烧温度及煅烧时间对LaPO4Ce,Tb纳米粒子发光性质的影响.     

纳米LaPO_4∶Ce,Tb的明胶网格沉淀法制备及发光研究

采用明胶网格沉淀法,成功制备了共掺铈、铽的磷酸镧纳米颗粒。用透射电子显微镜、X射线衍射仪及TG对产物的形貌、结构和热稳定性进行了表征。并研究了铈、铽含量,煅烧温度及煅烧时间对LaPO4∶Ce,Tb纳米粒子发光性质的影响。     

电感耦合等离子体原子发射光谱法测定镧铁合金、铈铁合金和镧铈铁合金中主量稀土

镧铁合金、铈铁合金和镧铈铁合金主要用作钕铁硼永磁材料或钢铁材料的稀土添加剂，而快速准确测定镧铁合金、铈铁合金和镧铈铁合金中主量稀土含量对产品的质量控制具有重要意义。采用盐酸-过氧化氢溶解样品，选择La 492.098 nm、Ce 447.124 nm为分析谱线，建立了电感耦合等离子体原子发射光谱法(ICP-AES)测定镧铁合金、铈铁合金和镧铈铁合金中主量稀土的分析方法。讨论了基体浓度、共存元素干扰等对测定的影响。结果表明，当铁质量浓度不大于0.2 mg/mL和镧(铈)质量浓度不大于20μg/mL时，基体效应可以忽略。样品中共存稀土元素和钙、镁、铝、锰、镍、硅、硫、磷等非稀土元素对稀土测定的影响可以忽略。镧、铈质量浓度在1.00～20.00μg/mL范围内与其对应的发射强度呈线性关系，校准曲线线性相关系数均为0.999 9。按照实验方法测定镧铁合金样品中镧，铈铁合金样品中铈，镧铈铁合金样品中镧、铈，结果的相对标准偏差为(RSD,n=11)均小于3%。按照实验方法测定镧铁合金、铈铁合金和镧铈铁合金内控样品的主量稀土含量，结果与草酸盐重量法测定结果一致。     

2009年3月23日稀土价格

2009年3月23日稀土价格,报价产品：金属镧,氧化镧,金属铈,氧化铈,金属镨,氧化镨,金属钕,氧化钕,镨钕氧化物,镨钕合金,金属钐,氧化钐,氧化铕,金属钆,金属铽,氧化铽,金属镝,氧化镝,氧化铒,氧化钇,镨钕镝合金,金属钇,混合稀土金属,电池级混合稀土金属,富镧金属,富铈金属,镝铁合金。     

2009年12月30日稀土价格

2009年9月30日稀土价格报价产品：金属镧．氧化镧．金属铈．氧化铈．金属镨．氧化镨,金属钕．氧化钕,镨钕氧化物,镨钕合金,金属钐．氧化钐．氧化铕．金属钆,金属铽．氧化铽,金属镝．氧化镝．氧化铒．氧化钇．镨钕镝合金．金属钇。混合稀土金属．电池级混合稀土金属．富镧金属．富铈金属,镝铁合金等稀土金属价格。     

2009年6月26日稀土价格

2009年6月26日稀土价格报价产品：金属镧．氧化镧,金属铈,氧化铈．金属镨．氧化镨,金属钕．氧化钕,镨钕氧化物,镨钕合金．金属钐,氧化钐．氧化铕．金属钆,金属铽．氧化铽,金属镝．氧化镝．氧化铒,氧化钇,镨钕镝合金．金属钇。混合稀土金属,电池级混合稀土金属．富镧金属．富铈金属。镝铁合金等稀土金属价格。     

2009年9月30日稀土价格

2009年9月30日稀土价格报价产品：金属镧,氧化镧,金属铈．氧化铈,金属镨．氧化镨．金属钕．氧化钕．镨钕氧化物,镨钕合金,金属钐,氧化钐．氧化铕．金属钆,金属铽,氧化铽,金属镐．氧化镝,氧化铒,氧化钇,镨钕镝合金,金属钇。混合稀土金属,电池级混合稀土金属,富镧金属．富铈金属．镝铁合金等稀土金属价格。     

ICP-OES法测定磷酸镧铈铽中16种元素的含量

迄今尚未发现测定磷酸镧铈铽中稀土杂质的报道,本文利用高分辨率电感耦合等离子体发射光谱仪,采用基体匹配法同时测定磷酸镧铈铽中的12种稀土杂质和A1、Cu、Ni、Zn4种非稀土杂质.本方法使用微波消解仪消解样品后直接测定,选择了合适的仪器工作参数及分析谱线,研究了酸度、基体组分等对测试结果的影响,各稀土杂质元素检出限均小于0.0010％,加标回收率在86％-113％,非稀土杂质元素检出限均小于0.0020％,加标回收率在91％-111％,结果与电感耦合等离子体质谱法(ICP-MS)测定结果一致,操作简便快捷,方法实用可行.     

硼磷酸钇基质中Ce3+、Tb3+、Gd3+的发光及能量传递

用 BPO4 和稀土氧化物为原料 ,首次合成了铈、铽、钆共激活的硼磷酸钇绿色荧光粉 ,研究了基质中Ce3 、Tb3 、Gd3 的发光以及它们之间的相互作用。该基质中存在 Ce3 → Tb3 、Gd3 → Tb3 的能量传递 ,以及 Ce3 和 Gd3 之间的竞争吸收和独自发射。在铈、铽共激活的硼磷酸钇体系中掺入钆后 ,Ce3 的发射以及 Tb3 的 5D4 → 7FJ和 5D3→ 7FJ的发射均增强 ,但总的效果是 Gd3 阻碍了 Ce3 → Tb3 的能量传递。基质中钇全部被钆代替后 ,荧光粉的发光亮度增加 ,光纯度也较好 ,发光色坐标 X值稍变小。     

Recovery of free ADP, Pi, and free energy of ATP hydrolysis in human skeletal muscle

BACKGROUND: Recent studies have demonstrated that a high concentration of phosphate directly stimulates parathyroid hormone (PTH) secretion. High serum levels of phosphate are usually observed in patients with end-stage renal disease. The aim of the present study was to evaluate whether serum phosphate concentration had an acute effect on PTH secretion in hemodialysis patients. The levels of serum phosphate were manipulated during the hemodialysis session by using a phosphate free dialysate or a dialysate with a high content of phosphate. METHODS: Ten stable hemodialysis patients with PTH values above 300 pg/ml were included in the study. A PTH-calcium curve was obtained during both high phosphate and phosphate free hemodialysis. RESULTS: The serum phosphate concentration remained high (2.17 +/- 0.18 mM) throughout the high phosphate hemodialysis and decreased progressively to normal levels (1.02 +/- 0.06 mM) during the phosphate free hemodialysis. The serum PTH levels at maximal inhibition by hypercalcemia (minimal PTH) were greater during the high phosphate than the phosphate free hemodialysis (413 +/- 79 vs. 318 +/- 76 pg/ml, P < 0.003). In all patients the values of minimum PTH were greater during the high phosphorus than the phosphorus free hemodialysis. The values of maximally stimulated PTH during hypocalcemia and the set point of the PTH-calcium curve were similar during the high phosphate and the phosphate free hemodialysis. CONCLUSION: The maintenance of high serum phosphorus levels during hemodialysis prevented, in part, the inhibition of PTH secretion by calcium, which strongly suggests that in hemodialysis patients high serum phosphate contributes directly to the elevation of PTH levels despite normal or high serum calcium concentration.     

生物提金氧化液中铁的选择性沉淀

以生物提金氧化液为研究对象,采用磷酸氢二铵（（NH4）2HPO4）作为沉淀剂,研究了pH值、温度、加料方式、（NH4）2HPO4浓度和沉淀反应时间对生物提金氧化液中铁的选择性沉淀的影响。采用同时流加生物提金氧化液和0.2 g/mL（NH4）2HPO4溶液的方式,控制（NH4）2HPO4流速将沉淀体系的pH值调节为2.0,在60 ℃条件下搅拌反应2.5 h,铁沉淀率达到95.2%,砷存留率为93.6%,XRD图谱证实了铁沉淀主要是磷酸铁（FePO4）和三聚磷酸二氢铁（FeH2P3O10）,实现了生物提金氧化液中铁的选择性沉淀,为从生物提金氧化液中综合回收铁、砷等有价成分提供了理论指导。     

On the protection by inorganic phosphate of calcium-induced membrane permeability transition

The role of inorganic phosphate as inhibitor of mitochondrial membrane permeability transition was studied. It is shown that in mitochondria containing a high phosphate concentration, i.e., 68 nmo/mg, Ca2+ did not activate the pore opening. Conversely, at lower levels of matrix phosphate, i.e., 38 nmol/mg, Ca2+ was able to induce subsequent pore opening. The inhibitory effect of phosphate was apparent in sucrose-based media, but it was not achieved in KCI media. The matrix free Ca2+ concentration and matrix pH were lowered by phosphate, but they were always higher in K+-media. In the absence of ADP, phosphate strengthened the inhibitory effect of cyclosporin A on carboxyatractyloside-induced Ca2+ efflux. Acetate was unable to replace phosphate in the induction of the aforementioned effects. It is concluded that phosphate preserves selective membrane permeability by diminishing the matrix free Ca2+ concentration.     

Mechanical strength of calcium phosphate cement in vivo and in vitro

Two different kinds of calcium phosphate cement were developed for implant fixation: cement A comprised of alpha-tricalcium phosphate (alpha-TCP) 95% and dicalcium phosphate dihydrate (DCPD) 5%, and cement B comprised of alpha-tricalcium phosphate 90% and dicalcium phosphate dihydrate 10%. The compression strength and pullout force of the new materials were tested both in vitro and in vivo. Microscopic observations were performed on the interface between bone and cement. Cement A showed a greater mechanical strength than cement B. The results suggest the clinical possibility of this calcium phosphate cement, which could be used as a material for enhancing implant fixation.     

Phosphate deficiency as a rare cause of osteomalacia--case report of several years of enteral feeding and antacid therapy

HISTORY AND CLINICAL FINDINGS: Floor-of-the-mouth cancer had been diagnosed and surgically treated in a 55-year-old man 4 years before the latest admission. For the last 3 years he had been fed through a percutaneous endoscopic gastrostomy (PEG). Since then he had experienced reflux oesophagitis which was being treated with aluminium-containing antacids. He was hospitalized for the surgical treatment of bilateral fractures of the neck of the femur. A surgical biopsy revealed osteomalacia but no metastasis. INVESTIGATIONS: The serum phosphate level was significantly reduced (0.21 mmol/l) and there was no detectable phosphate excretion in the 24-hour urine. Serum calcium concentration was unremarkable, but there was hypercalciuria (34.4 mmol/d). Alkaline phosphate activity was significantly raised (393 U/l) and parathormone level reduced (7 ng/l). Vitamin D concentration was unremarkable. TREATMENT AND COURSE: The phosphate content in the parenteral feed was at first increased and additional phosphate was given by mouth. The calcium and phosphate levels slowly became normal only after medication had been changed from antacids to H2-blockers. CONCLUSIONS: In this case osteomalacia was caused not by vitamin D deficiency but by a lack of phosphate. The reduced intestinal phosphate absorption by the antacids only partially explains the pronounced clinical signs. If antacids are taken over long periods the phosphate balance should be carefully monitored to avoid osteomalacia.     

Formation of hydroxyapatite in new calcium phosphate cements

Tetracalcium phosphate (TTCP) has been shown previously to be an essential component of self-setting calcium phosphate cements that form hydroxyapatite (HA) as the only end-product. We report herein on a new self-setting calcium phosphate cement that does not contain TTCP. These cements consist of dicalcium phosphate anhydrous (DCPA), dicalcium phosphate dihydrate (DCPD), alpha-tricalcium phosphate, or amorphous calcium phosphate and, as an additional source of calcium, calcium hydroxide or calcium carbonate. These cements require the use of a phosphate (0.2 moll(-1) or higher) solution or a high pH solution as the cement liquid. The cements harden in relatively short time (5-30 min) and form HA as the dominant end-product in 24 h. The diametral tensile strengths of the 24-h samples are in the range of 0.2 to 7.5 MPa. Results from X-ray diffraction studies suggest that the cement setting is caused by rapid HA formation induced by the high phosphate concentration of the cement liquid. Because DCPA and DCPD are highly soluble at pH values above 12.7, which is the pK3 of phosphoric acid, high phosphate concentration in the slurry solution was also attainable by using a highly alkaline solution as the cement liquid. The physicochemical properties of these cements are comparable to those of TTCP-containing cements, and the new cements may be expected to have in vivo characteristics similar to those of TTCP-containing cements as well.     

Symmetrical generalization between the discriminative stimulus effects of gamma-hydroxybutyric acid and ethanol: occurrence within narrow dose ranges

Etoposide phophate is a phosphate ester prodrug of etoposide designed to improve the pharmaceutical characteristics of the parent compound. A Phase I dose-escalating study of etoposide phosphate was conducted concurrently at two institutions to determine its toxicity, pharmacokinetics, and maximum tolerated dose. Etoposide phosphate was administered i.v. for 30 min on days 1, 3, and 5 every 21 days or on recovery from toxicity. Cohorts of at least three patients received etoposide phosphate at dose levels from 50 mg/m2 to 150 mg/m2 expressed as molar equivalents of etoposide. Blood and urine samples were obtained from all patients during the first cycle of treatment and the concentrations of etoposide phosphate and etoposide were measured. Thirty-nine patients with documented cancers received a total of 75 cycles of etoposide phosphate. The dose-limiting toxicity was myelosuppression which occurred at the 150-mg/m2 etoposide equivalent dose. Etoposide phosphate was rapidly and extensively converted to etoposide. No measurable etoposide phosphate was detectable in the plasma by 15-60 min after the end of the infusion. The mean half-life of etoposide at the different dose levels ranged from 5.5 to 9.3 h. The pharmacokinetics of etoposide, generated from etoposide phosphate, was linear over the dose range studied and was comparable to results reported in the literature for i.v. etoposide. In summary, i.v. etoposide phosphate is rapidly and extensively converted to etoposide. The maximum tolerated dose of etoposide phosphate when given on days 1, 3, and 5 is 150 mg/m2/day. The dose-limiting toxicity is myelosuppression. The maximum tolerated dose and adverse event profile are consistent with those of etoposide.     

Investigation on Structures and Properties of Yb3＋-Doped Laser Glasses

The Yb3^＋ -doped silicate, phosphate and borophosphate laser glasses were prepared by means of conventional melt quenching technology. The physical and spectral properties of the glasses were investigated. The results show that, due to the existence of OH^-, the fluorescence lifetime of phosphate glass is shorter than that of silicate glass, so silicate glass has better spectral properties than phosphate glass. Silicate glass has better mechanical and thermal properties than phosphate glass, but with the addition of B2O3, mechanical and thermal properties of phosphate glass are improved greatly without fluorescence quenching effect. This kind of borophosphate glass can be used in high average power solid state lasers.     

Intravenous repletion of phosphorus deficiency in the chronic renal failure patients with severe hypophosphatemia

Severe hypophosphatemia is a potentially life-threatening medical condition and might lead to a fatal outcome in critically ill patients. The situation is further complicated by the co-morbid renal failure. We evaluated the efficacy and safety of the intravenous phosphate repletion in 15 renal failure patients with severe hypophosphatemia. Six patients with advanced renal failure and nine patients under maintenance hemodialysis, 7 males and 8 females, aged between 42 and 83 years old, were found to have serum phosphate level < 1.2 mg/dL from various medical conditions and were treated with intravenous phosphate infusion. The phosphate solution prepared from sodium dihydrogen phosphate (NaH2PO4), containing 13 mg/ml phosphate and 0.5 meq/ml sodium, in the dosage 2.5-3.0 mg phosphate/Kg body weight, was administered through the central venous lins every 6-8 hours. The infusion was discontinued once serum phosphate level reached 5.0-5.5 mg/dL. Serum ionized calcium, phosphate and intact parathyroid hormone levels were serially followed at different intervals, respectively. The hemodialyzed uremic patients received their dialysis treatment as scheduled. All patients survived the hypophosphatemic period and regained normal phosphate levels after repletion. The amount of phosphate administered to reach the target level ranged between 3438 and 9150 mg and the duration of treatment varied between six and seventeen days. Hypocalcemia (< 4.2 mg/dL) was noted at eight occasions during the whole treatment period but none was symptomatic. Eleven patients recovered from the offending illness. However, four patients expired due to reasons not directly consequent to and temporally remote from hypophosphatemia. We conclude that prompt repletion of severe hypophosphatemia and phosphate deficiency with relatively slower rate of NaH2PO4 solution intravenous infusion is a safe and effective mode of treatment for renal failure and uremic patients. The longer treatment period allowed the administered minerals full equilibration. The risk of hyperkalemia is avoided and the sodium/volume load can be eliminated by dialysis.     

碱性条件下磷酸盐分解白钨试验研究

研究了在碱性条件下以磷酸钠为浸出剂分解白钨的影响因素,实验表明,影响白钨分解率的主要因素为磷酸钠的用量,其次为氢氧化钠的用量;较优的工艺条件是氢氧化钠用量为它与钨酸钙单独反应时所需理论量的1.6倍,磷酸钠用量为它与钨酸钙单独反应时所需理论量的1.8倍,保温时间为4 h,温度为270℃,搅拌速度为950r/min,液固比为3∶1。