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PubMed1996

Pharmacokinetics of germanium after po beta-carboxyethylgermanium sesquioxide in 24 Chinese volunteers.

AIM: To compare the pharmacokinetics after po different doses of beta-carboxyethylgermanium sesquioxide (Ge-132). METHODS: An atomic absorption spectrophotometric system was used to measure germanium concentrations in plasma and urine samples after po Ge-132 1 (low dose, LD), 2.5 (medium dose, MD), and 4 (high dose, HD) g.m-2 in 24 healthy volunteers (one dose per 8 subjects). RESULTS: T1/2 alpha (LD, 1.2 +/- 0.7 h; MD, 1.1 +/- 0.6 h; HD, 1.2 +/- 0.5 h), T1/2 beta (LD, 5.2 +/- 1.2 h; MD, 5.8 +/- 2.5 h; HD, 5.5 +/- 1.4 h) and Cl/F (LD, 33 +/- 12 L.h-1; MD, 35 +/- 10 L.h-1; HD, 33 +/- 11 L.h-1) were not dose-related. Tmax was between 0.75 h and 2 h. Cmax (LD, 5.3 +/- 2.2 mg.L-1; MD, 13 +/- 5 mg.L-1; HD 18 +/- 8 mg.L-1, HD) and AUC (LD, 31 +/- 13 mg.h.L-1; MD, 60 +/- 16 mg.h.L-1; HD, 79 +/- 42 mg.h.L-1) were positive correlation to the dose of Ge-132. Urine-eliminated germanium within 24 h accounted for 11 +/- 3% of LD, 9 +/- 3% of MD, and 6 +/- 5% of HD (calculated from Ge/F) and showed a negative correlation to the dose. CONCLUSION: 1) Intracorporal process of Ge after po Ge-132 coincided with the first-order absorption and elimination with two-compartment kinetic model; 2) The amount of germanium eliminated in urine was below 11%.

Adult↗

PubMed2004

High-resolution solid-state 73Ge NMR spectra of hexacoordinated germanium compounds.

High-resolution solid-state magic angle spinning 73Ge NMR spectra of hexavalent germanium compounds, i.e. diiodogermylene (1a) and bis(1-pyrrolyl)(meso-tetraphenylporphyrinato)germanium (3a), were determined. To the best of our knowledge, this is the first example of high-resolution solid-state 73Ge NMR spectra of hexacoordinated germanium nuclei. The symmetry requirement for observation of high-resolution solid-state 73Ge NMR spectra is discussed.

Journal Article↗

PubMed2002

Comparison of chloride- and hydride-generation for quantitation of germanium by headspace solid-phase microextraction-inductively coupled plasma-mass spectrometry.

Chloride- and hydride-generation headspace solid-phase microextraction (SPME) techniques have been compared for the detection of trace amounts of germanium by inductively coupled plasma time-of-flight mass spectrometry (ICP-TOFMS). The conditions for generation of germanium chloride, including acid type and concentration, effect of sodium chloride and extraction time, were investigated. Detection limits of 20 and 92 pg mL(-1) and precisions of 18% (n=11) and 9.7% (n=11) were achieved for chloride and hydride generation, respectively, at a concentration of 10 ng mL(-1). The generated germanium chloride and hydride species identities were characterized and confirmed as GeCl(4) and GeH(4) by use of electron-impact ionization mass spectrometry. Chloride generation coupled with SPME sampling and ICP-TOFMS detection resulted in twofold enhancement of sensitivity compared to GeH(4)and detection limits for continuous hydride generation were 20-fold better than reported atomic fluorescence data.

Journal Article↗

PubMed1990

Microbial interactions with germanium.

Germanium is a semi-precious, widely-dispersed, and biologically non-essential metal with considerable potential for application in the fields of electronics, computer engineering and medicine. Research on the physiology and genetics of germanium toxicity and accumulation in microorganisms has received scant attention. An understanding of these aspects is important from both fundamental and applied points of view. This review will examine the diverse range of interactions between germanium and microbial species.

Journal Article↗

PubMed2001

The response of high-purity germanium detectors to X-rays with energy in the region of the Ge K-absorption edge.

The response of a high-purity germanium detector to X-rays in the 8-15-keV energy region has been investigated. The w-value and energy resolution dependencies on the X-ray energy have been studied. No abrupt variation of w is observed at the germanium K absorption-edge (11.104-keV). The detector energy resolution follows a characteristic linear dependence on Ex(-1/2) over the whole energy range. Both features are consistent with the absence of intrinsic nonlinearity effects in germanium at the K-edge.

Journal Article↗

PubMed2005

Density functional study of 8- and 11-vertex polyhedral borane structures: comparison with bare germanium clusters.

Density functional theory (DFT) at the hybrid B3LYP level has been applied to the polyhedral boranes B(n)H(n)(z) (n = 8 and 11, z = -2, -4, and -6) for comparison with isoelectronic germanium clusters Ge(n)(z). The energy differences between the global minima and other higher energy borane structures are much larger relative to the case of the corresponding bare germanium clusters. Furthermore, for both B(8)H(8)(2-) and B(11)H(11)(2-), the lowest energy computed structures are the corresponding experimentally observed most spherical deltahedra predicted by the Wade-Mingos rules, namely the D(2)(d) bisdisphenoid and the C(2)(v) edge-coalesced icosahedron, respectively. Only in the case of B(8)H(8)(2-) is there a second structure close (+2.6 kcal/mol) to the D(2)(d) bisdisphenoid global minimum, namely the C(2)(v) bicapped trigonal prism corresponding to the "square" intermediate in a single diamond-square-diamond process that can lead to the experimentally observed room temperature fluxionality of B(8)H(8)(2-). Stable borane structures with 3-fold symmetry (e.g., D(3)(h), C(3)(v), etc.) are not found for boranes with 8- and 11-vertices, in contrast to the corresponding germanium clusters where stable structures derived from the D(3)(d) bicapped octahedron and D(3)(h) pentacapped trigonal prism are found for the 8- and 11-vertex systems, respectively. The lowest energy structures found for the electron-rich boranes B(8)H(8)(4-) and B(11)H(11)(4-) are nido polyhedra derived from a closo deltahedron by removal of a relatively high degree vertex, as predicted by the Wade-Mingos rules. They relate to isoelectronic species found experimentally, e.g., B(8)H(12) and R(4)C(4)B(4)H(4) for B(8)H(8)(4-) and C(2)B(9)H(11)(2-) for B(11)H(11)(4-). Three structures were found for B(11)H(11)(6-) with arachno type geometry having two open faces in accord with the Wade-Mingos rules.

Journal Article↗

PubMed2000

New calcium germanium nitrides: Ca2GeN2, Ca4GeN4, and Ca5Ge2N6.

We report three new calcium germanium nitrides synthesized as crystals from the elements in sealed niobium tubes at 760 degrees C using liquid sodium as a growth medium. Black Ca2GeN2 is isostructural with the previously reported strontium analogue. It is tetragonal P4(2)/mbc (no. 135) with a = 11.2004(8) A, c = 5.0482(6) A, and Z = 8. It contains GeN2(4-) units which have 18 valence electrons, and consequently are bent, like the isoelectronic molecule SO2. In contrast, clear, orange Ca4GeN4 with fully oxidized germanium contains isolated GeN4(8-) tetrahedra and is monoclinic P2(1)/c (no. 14) with a = 9.2823(8) A, b = 6.0429(5) A, c = 11.1612(9) A, beta = 116.498(6) degrees, and Z = 4. Clear, colorless Ca5Ge2N6, also with fully oxidized germanium, contains infinite chains, 1 infinity[GeN2N2/2(5-)], of corner-sharing tetrahedra similar to those found in pyroxenes. However, the precise structure of this latter phase has not yet been determined because of twinning problems.

Journal Article↗

PubMed2005

Synthesis of germanium nanocubes by a low-temperature inverse micelle solvothermal technique.

We present a low-temperature inverse micelle solvothermal approach for the synthesis of germanium nanocubes using the surfactant heptaethylene glycol monododecyl ether as a capping agent. X-ray diffraction results indicate that the as-prepared nanocubes are diamond-type pure germanium. Transmission electron microscopy observations show that the as-prepared germanium nanocubes have an edge length of 100 +/-20 nm, highly crystallized.

Journal Article↗

PubMed2002

Macroporous germanium by electrochemical deposition.

Germanium is electrodeposited in a template formed from a dried suspension of silica spheres. The germanium completely fills the pores of the silica matrix. The semiconductor, as deposited, is amorphous but can be crystallized by annealing. Selective dissolution of the silica template gives a macroporous germanium-air sphere matrix, which offers interesting possibilities for photonic applications.

Journal Article↗

PubMed2006

Search for global-minimum geometries of medium-sized germanium clusters. II. Motif-based low-lying clusters Ge21-Ge29.

We performed a constrained search for the geometries of low-lying neutral germanium clusters Ge(N) in the size range of 21 < or = N < or = 29. The basin-hopping global optimization method is employed for the search. The potential-energy surface is computed based on the plane-wave pseudopotential density functional theory. A new series of low-lying clusters is found on the basis of several generic structural motifs identified previously for silicon clusters [S. Yoo and X. C. Zeng, J. Chem. Phys. 124, 054304 (2006)] as well as for smaller-sized germanium clusters [S. Bulusu et al., J. Chem. Phys. 122, 164305 (2005)]. Among the generic motifs examined, we found that two motifs stand out in producing most low-lying clusters, namely, the six/nine motif, a puckered-hexagonal-ring Ge6 unit attached to a tricapped trigonal prism Ge9, and the six/ten motif, a puckered-hexagonal-ring Ge6 unit attached to a bicapped antiprism Ge10. The low-lying clusters obtained are all prolate in shape and their energies are appreciably lower than the near-spherical low-energy clusters. This result is consistent with the ion-mobility measurement in that medium-sized germanium clusters detected are all prolate in shape until the size N approximately 65.

Journal Article↗

PubMed2003

Phase transitions in KTP isostructures: correlation between structure and Tc in germanium-doped RbTiOPO4.

Crystals of germanium-doped rubidium titanyl phosphate, Rb(2)(Ti)(Ge(0.121)Ti(0.879))O(2)(PO(4))(2) (GeRTP#1) and Rb(2)(Ge(0.125)Ti(0.875))(Ge(0.225)Ti(0.775))O(2)(PO(4))(2) (GeRTP#2), have been structurally characterized from X-ray diffraction data at room temperature. In addition, a third structure, Rb(2)(TiO)(2)(PO(4))(2) (RTP), has been reinvestigated. The exchange of titanium for germanium results in a less distorted octahedral coordination around the two crystallographically independent titanium sites. Additionally, rubidium split-cation positions have been found in these doped RTP crystals. Dielectric measurements show that the phase-transition temperature, T(c), decreases with increasing germanium concentration, and a direct correlation between the room-temperature split of the rubidium cations and T(c) has been discovered. General trends regarding the relationship between the room-temperature structures of KTP-like compounds and their T(c) values are discussed.

Journal Article↗

PubMed1996

Wide dynamic range germanium detector for perturbation crystallography.

An IR detector based on a cooled germanium photodetector has been tested for applications in X-ray diffraction. The detector can be used simultaneously in photon-counting mode and current mode giving a dynamic range from < 1 to 10(9) photons s(-1). Since germanium is used as the photodetector, its efficiency at energies above 25 keV is much better than the silicon equivalents. The detector proved to be highly linear both in the low-flux region (< 10(5) photons s(-1)) where photon counting is used and in the high-flux region (> 10(5) photons s(-1)) where the detector is run in current mode. The response time of the detector is of the order of 1 mus, making it suitable for studies in perturbation crystallography, especially when coupled to a lock-in amplifier. As an example, the shift of a reflection of LiNbO(3) induced by an external electric field was determined with the germanium detector and lock-in amplifier.

Journal Article↗

PubMed1986

Binding of Germanium to Pseudomonas putida Cells.

The binding of germanium to Pseudomonas putida ATCC 33015 was investigated by using whole intact cells grown in a medium supplemented with GeO(2) and catechol or acetate. Electron-microscopic examination of the control and metal-loaded samples revealed that germanium was bound within the cell envelope. A certain number of small electron-dense deposits of the bound element were found in the cytoplasm when the cells were grown in the presence of GeO(2) and catechol. The study of germanium distribution in cellular fractions revealed that catechol facilitated the intracellular accumulation of this element.

Journal Article↗

PubMed2006

[Precipitation trapping with phenylfluorone and determination of trace gallium, germanium, molybdenum and indium by GFAAS].

The preconcentration of trace gallium, germanium, molybdenum and indium by trapping with precipitation of phenylfluorone (PF), and the determination of the elements by GFAAS were developed. The effects such as those of acidity, amounts of PF, aging time, volume of test solution, and the coexistent ions on the preconcentration of the trace elements were examined in detail. The optimum conditions of preconcentration for Ga(III) were pH approximately 2 test solution 500 mL with added 10.00 mg x mL(-1) PF (2.00 mL) and aging for 4 h, those for Ge(IV) were pH approximately 2 test solution 500 mL with added 10.00 mg x mL(-1) PF (4.00 mL) and aging for 10 h, those for Mo(V) were pH approximately 3 test solution 1 000 mL with added 10.00 mg x mL(-1) PF (3.00 mL) and aging for 6 h, and those for In(III) were pH approximately 5 test solution 100 mL with added 10.00 mg x mL(-1) PF (3.00 mL) and aging for 10 h. The experiment results showed that the main contribution to trapping trace gallium, germanium, molybdenum and indium with PF precipitation was post-precipitation instead of coprecipitation. The detection limits (3s) were 0.12 ng x mL(-1) for gallium, 0.30 ng x mL(-1) for germanium, 0.046 ng x mL(-1) for molybdenum and 2.7 ng x mL(-1) for indium. The developed methods were successfully applied to the determination of trace amount of the elements in water samples, geological standard reference materials, and zinc concentrate samples by graphite furnace atomic absorption spectrometry.

English Abstract↗

PubMed2006

[Determination of trace germanium by HG-ICP and study on the medium influence].

A method to determine the content of trace germanium by hydride generation inductively coupled plasma atomic emission spectrometry was established. The influences of different acidic medium, concentration of NaBH4 and other concomitant elements are examined systemically. The optimal analytical conditions were discussed and examined. The detection limit is 0.2 ng x mL(-1) and the precision is 0.9%. The value of germanium content detected in environmental reference material agrees with the certified value. The medium influence on determining trace germanium was studied in detail.

English Abstract↗

PubMed1997

Evaporated germanium films as supports for microanalysis of carbon and silicon containing specimens.

A preparation procedure is described for producing specimen supports of evaporated germanium. The germanium film is used as a replacement for films of carbon and silicon when microanalytical techniques like energy dispersive X-ray microanalysis (XRMA) or electron energy loss spectroscopy (EELS) are focusing on particulates containing these elements. The supports can be produced with high reproducibility within a thickness range of 15 to 30 nm and of a quality suitable also for high resolution transmission electron microscopy.

Animals↗

PubMed2005

Temperature-dependent growth of germanium oxide and silicon oxide based nanostructures, aligned silicon oxide nanowire assemblies, and silicon oxide microtubes.

We demonstrate the temperature-dependent growth of germanium oxide and silicon oxide based composite nanostructures (multiple nanojunctions of Ge nanowires and SiO(x) nanowires, Ge-filled SiO(2) nanotubes, Ge/SiO(2) coaxial nanocables, and a variety of interesting micrometer-sized structures), aligned SiO(x) nanowire assemblies, and SiO(x) microtubes. The structures were characterized by SEM, TEM, energy-dispersive X-ray spectroscopy, and electron diffraction. The combination of laser ablation of a germanium target and thermal evaoporation of silicon monoxide powders resulted in the formation of Ge and SiO(x) species in a carrier gas; the nano/micro-sized structures grow by either a Ge-catalyzed vapor-liquid-solid or a Ge-nanowire-templated vapor-solid process.

Crystallization↗

PubMed1994

Effects of germanium and silicon on bone mineralization.

The chemical properties of Ge are similar to Si. This study investigated whether Ge can substitute for, or is antagonistic to, Si in bone formation. Sixty male weanling Sprague-Dawley rats were randomly assigned to treatment groups of 12 and 6 in a 2 x 4 factorially arranged experiment. The independent variables were, per gram fresh diet, Si (as sodium metasilicate) at 0 or 25 micrograms and Ge (as sodium germanate) at 0, 5, 30, or 60 micrograms. Results confirmed that Ge does not enhance Si deprivation and provided evidence that Ge apparently can replace Si in functions that influence bone composition. When Si was lacking in the diet, calcium and magnesium concentrations of the femur were decreased; this was reversed by feeding either Ge and/or Si. Similar effects were found for zinc, sodium, iron, manganese, and potassium of vertebra. There were some responses to Si deprivation that Ge could not reverse; Ge did not increase femur copper, sodium, or phosphorus or decrease molybdenum of vertebra, effects that were evoked by Si supplementation. Additionally, some findings suggested that 60 micrograms Ge/g diet could be a toxic intake for the rat. On the other hand, some responses induced by Ge indicate that this element may be acting physiologically other than as a substitute for Si. Germanium itself affected bone composition. Germanium supplementation decreased Si and molybdenum in the femur and increased DNA in tibia. Regardless of the amount of Si fed, animals fed 30 micrograms Ge/g diet had increased tibial DNA compared to animals fed 0 or 60 micrograms Ge; however, tibial DNA of animals fed 30 micrograms Ge was not statistically different from those animals fed 5 micrograms Ge. Thus, Ge may be of nutritional importance.

Animals↗