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1.
J Am Chem Soc ; 137(23): 7448-55, 2015 Jun 17.
Artículo en Inglés | MEDLINE | ID: mdl-26051104

RESUMEN

The generation of chemical fuel in the form of molecular H2 via the electrolysis of water is regarded to be a promising approach to convert incident solar power into an energy storage medium. Highly efficient and cost-effective catalysts are required to make such an approach practical on a large scale. Recently, a number of amorphous hydrogen evolution reaction (HER) catalysts have emerged that show promise in terms of scalability and reactivity, yet remain poorly understood. In this work, we utilize Raman spectroscopy and X-ray absorption spectroscopy (XAS) as a tool to elucidate the structure and function of an amorphous cobalt sulfide (CoSx) catalyst. Ex situ measurements reveal that the as-deposited CoSx catalyst is composed of small clusters in which the cobalt is surrounded by both sulfur and oxygen. Operando experiments, performed while the CoSx is catalyzing the HER, yield a molecular model in which cobalt is in an octahedral CoS2-like state where the cobalt center is predominantly surrounded by a first shell of sulfur atoms, which, in turn, are preferentially exposed to electrolyte relative to bulk CoS2. We surmise that these CoS2-like clusters form under cathodic polarization and expose a high density of catalytically active sulfur sites for the HER.

2.
Nano Lett ; 14(10): 5883-90, 2014 Oct 08.
Artículo en Inglés | MEDLINE | ID: mdl-25222441

RESUMEN

Charge carrier dynamics in Co3O4 thin films are observed using high harmonic generation transient absorption spectroscopy at the Co M2,3 edge. Results reveal that photoexcited Co3O4 decays to the ground state in 600 ± 40 ps in liquid methanol compared to 1.9 ± 0.3 ns in vacuum. Kinetic analysis suggests that surface-mediated relaxation of photoexcited Co3O4 may be the result of hole transfer from Co3O4 followed by carrier recombination at the Co3O4-methanol interface.

3.
BMC Musculoskelet Disord ; 15: 40, 2014 Feb 11.
Artículo en Inglés | MEDLINE | ID: mdl-24517217

RESUMEN

BACKGROUND: Currently, Posterior Short Segment Pedicle Screw Fixation is a popular procedure for treating unstable thoracolumbar/lumbar burst fracture. But progressive kyphosis and a high rate of hardware failure because of lack of the anterior column support remains a concern. The efficacy of different methods remains debatable and each technique has its advantages and disadvantages. METHODS: A consecutive series of 20 patients with isolated thoracolumbar/lumbar burst fractures were treated by posterior short segment pedicle screw fixation and transforaminal thoracolumbar/lumbar interbody fusion (TLIF) between January 2005 and December 2007. All patients were followed up for a minimum of 2 years. Demographic data, neurologic status, anterior vertebral body heights, segmental Cobb angle and treatment-related complications were evaluated. RESULTS: The mean operative time was 167 minutes (range, 150-220). Blood loss was 450 ~ 1200 ml, an average of 820 ml. All patients recovered with solid fusion of the intervertebral bone graft, without main complications like misplacement of the pedicle screw, nerve or vessel lesion or hard ware failure. The post-operative radiographs demonstrated a good fracture reduction and it was well maintained until the bone graft fusion. Neurological recovery of one to three Frankel grade was seen in 14 patients with partial neurological deficit, three grades of improvement was seen in one patient, two grades of improvement was observed in 6 patients and one grade of improvement was found in 6 patients. All the 6 patients with no paraplegia on admission remained neurological intact, and in one patient with Frankel D on admission no improvement was observed. CONCLUSION: Posterior short-segment pedicle fixation in conjunction with TLIF seems to be a feasible option in the management of selected thoracolumbar/lumbar burst fractures, thereby addressing all the three columns through a single approach with less trauma and good results.


Asunto(s)
Tornillos Óseos , Fijación de Fractura/instrumentación , Vértebras Lumbares/cirugía , Fracturas de la Columna Vertebral/cirugía , Fusión Vertebral/instrumentación , Vértebras Torácicas/cirugía , Adolescente , Adulto , Pérdida de Sangre Quirúrgica , Trasplante Óseo , Femenino , Fijación de Fractura/efectos adversos , Curación de Fractura , Humanos , Vértebras Lumbares/diagnóstico por imagen , Vértebras Lumbares/lesiones , Vértebras Lumbares/fisiopatología , Masculino , Persona de Mediana Edad , Tempo Operativo , Oseointegración , Complicaciones Posoperatorias/etiología , Estudios Prospectivos , Diseño de Prótesis , Radiografía , Recuperación de la Función , Fracturas de la Columna Vertebral/diagnóstico , Fracturas de la Columna Vertebral/fisiopatología , Fusión Vertebral/efectos adversos , Vértebras Torácicas/diagnóstico por imagen , Vértebras Torácicas/lesiones , Vértebras Torácicas/fisiopatología , Factores de Tiempo , Resultado del Tratamiento , Adulto Joven
4.
ACS Appl Energy Mater ; 7(9): 4004-4015, 2024 May 13.
Artículo en Inglés | MEDLINE | ID: mdl-38756865

RESUMEN

Transition metal oxynitrides are a promising class of functional materials for photoelectrochemical (PEC) applications. Although these compounds are most commonly synthesized via ammonolysis of oxide precursors, such synthetic routes often lead to poorly controlled oxygen-to-nitrogen anion ratios, and the harsh nitridation conditions are incompatible with many substrates, including transparent conductive oxides. Here, we report direct reactive sputter deposition of a family of zirconium oxynitride thin films and the comprehensive characterization of their tunable structural, optical, and functional PEC properties. Systematic increases of the oxygen content in the reactive sputter gas mixture enable access to different crystalline structures within the zirconium oxynitride family. Increasing oxygen contents lead to a transition from metallic to semiconducting to insulating phases. In particular, crystalline Zr2ON2-like films have band gaps in the UV-visible range and are n-type semiconductors. These properties, together with a valence band maximum position located favorably relative to the water oxidation potential, make them viable photoanode candidates. Using chopped linear sweep voltammetry, we indeed confirm that our Zr2ON2 films are PEC-active for the oxygen evolution reaction in alkaline electrolytes. We further show that high-vacuum annealing boosts their PEC performance characteristics. Although the observed photocurrents are low compared to state-of-the-art photoanodes, these dense and planar thin films can offer a valuable platform for studying oxynitride photoelectrodes, as well as for future nanostructuring, band gap engineering, and defect engineering efforts.

5.
J Mater Chem A Mater ; 10(22): 12026-12034, 2022 Jun 07.
Artículo en Inglés | MEDLINE | ID: mdl-35757488

RESUMEN

We demonstrate a facile approach to solution-based synthesis of wafer-scale epitaxial bismuth vanadate (BiVO4) thin films by spin-coating on yttria-stabilized zirconia. Epitaxial growth proceeds via solid-state transformation of initially formed polycrystalline films, driven by interface energy minimization. The (010)-oriented BiVO4 films are smooth and compact, possessing remarkably high structural quality across complete 2'' wafers. Optical absorption is characterized by a sharp onset with a low sub-band gap response, confirming that the structural order of the films results in correspondingly high optoelectronic quality. This combination of structural and optoelectronic quality enables measurements that reveal a strong optical anisotropy of BiVO4, which leads to significantly increased in-plane optical constants near the fundamental band edge that are of particular importance for maximizing light harvesting in semiconductor photoanodes. Temperature-dependent transport measurements confirm a thermally activated hopping barrier of ∼570 meV, consistent with small electron polaron conduction. This simple approach for synthesis of high-quality epitaxial BiVO4, without the need for complex deposition equipment, enables a broadly accessible materials base to accelerate research aimed at understanding and optimizing photoelectrochemical energy conversion mechanisms.

6.
Acc Chem Res ; 43(10): 1364-74, 2010 Oct 19.
Artículo en Inglés | MEDLINE | ID: mdl-20954751

RESUMEN

Proton-coupled electron transfer reactions form the basis of many important chemical processes including much of the energy conversion that occurs within living cells. However, much of the physical chemistry that underlies these reaction mechanisms remains poorly understood. In this Account, we report on recent progress in the understanding of excited-state intramolecular proton-coupled electron transfer (PCET) reactions. The strategic design and synthesis of various types of PCET molecules, along with steady-state and femtosecond time-resolved spectroscopy, have uncovered the mechanisms of several excited-state PCET reactions in solution. These experimental advancements correlate well with current theoretical models, in which the proton has quantum motion with a high probability of tunneling. In addition, the rate of proton transfer is commonly incorporated within the rate of rearrangement of solvent molecules. As a result, the reaction activation free energy is essentially governed by the solvent reorganization because the charge redistribution is considered based on a solvent polarity-induced barrier instead of the height of the proton migration barrier. In accord with this theoretical basis, we can rationalize the observation that the proton transfer for many excited-state PCET systems occurs during the solvent relaxation time scale of 1-10 ps: the highly exergonic reaction takes place before the system reaches its equilibrium polarization. Also, we have used various derivatives of proton transfer molecules, especially those of 3-hydroxyflavone to clearly demonstrate how researchers can tune the dynamics of excited-state PCET through changes in the magnitude or direction of the dipole vector within the reaction. Subsequently, using 2-(2'-hydroxyphenyl)benzoxazole as the parent model, we then report on methods for the development of an ideal system for probing PCET reaction. Because future biomedical applications of such systems will likely occur in aqueous environments, we discuss various 7-azaindole analogues, for which proton transfer requires the assistance of protic solvent molecules. These results provide a unique contrast to the ubiquitous studies on the dynamic solvent effects of PCET molecules that undergo intrinsic intramolecular proton motion.

7.
ACS Appl Mater Interfaces ; 13(20): 23575-23583, 2021 May 26.
Artículo en Inglés | MEDLINE | ID: mdl-33998233

RESUMEN

The photoelectrochemical performance of thin film photoelectrodes can be impacted by deviations from the stoichiometric composition, both at the macroscale and at the nanoscale. This issue is especially pronounced for the class of ternary compounds that are currently investigated for simultaneously achieving the optoelectronic characteristics and chemical stability required for solar fuel generation. Here, we combine macroscopic photoelectrochemical testing with atomic force microscopy (AFM) and scanning transmission X-ray microscopy (STXM) to reveal relationships between photoelectrochemical activity, nanoscale morphology, and local chemical composition in copper vanadate (CVO) thin films as a model system. For films with varying Cu/(Cu + V) ratios around the ideal stoichiometry of stoiberite Cu5V2O10, AFM resolves submicrometer morphology variations, which correlate with variations of the Cu content resolved by STXM. Both stoichiometric and Cu-deficient films exhibit a clear photoresponse, which indicates electronic tolerance to reduced Cu content. While both films exhibit homogeneous O and V content, they are also characterized by local regions of Cu enrichment and depletion that extend beyond individual grains. By contrast, Cu-rich photoelectrodes exhibit a tendency toward CuO secondary phase formation and a significantly reduced photoelectrochemical activity, indicating a significantly poor electronic tolerance to Cu-enrichment. These findings highlight that the average film composition at the macroscale is insufficient for defining structure-function relationships in complex ternary compounds. Rather, correlating microscopic variations in chemical composition to macroscopic photoelectrochemical performance provides insights into photocatalytic activity and stability that are otherwise not apparent from pure macroscopic characterization.

8.
J Mater Chem A Mater ; 9(36): 20653-20663, 2021 Sep 21.
Artículo en Inglés | MEDLINE | ID: mdl-34671478

RESUMEN

The (opto)electronic properties of Ta3N5 photoelectrodes are often dominated by defects, such as oxygen impurities, nitrogen vacancies, and low-valent Ta cations, impeding fundamental studies of its electronic structure, chemical stability, and photocarrier transport. Here, we explore the role of ammonia annealing following direct reactive magnetron sputtering of tantalum nitride thin films, achieving near-ideal stoichiometry, with significantly reduced native defect and oxygen impurity concentrations. By analyzing structural, optical, and photoelectrochemical properties as a function of ammonia annealing temperature, we provide new insights into the basic semiconductor properties of Ta3N5, as well as the role of defects on its optoelectronic characteristics. Both the crystallinity and material quality improve up to 940 °C, due to elimination of oxygen impurities. Even higher annealing temperatures cause material decomposition and introduce additional disorder within the Ta3N5 lattice, leading to reduced photoelectrochemical performance. Overall, the high material quality enables us to unambiguously identify the nature of the Ta3N5 bandgap as indirect, thereby resolving a long-standing controversy regarding the most fundamental characteristic of this material as a semiconductor. The compact morphology, low defect content, and high optoelectronic quality of these films provide a basis for further optimization of photoanodes and may open up further application opportunities beyond photoelectrochemical energy conversion.

9.
Mater Horiz ; 8(6): 1744-1755, 2021 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-34846504

RESUMEN

The binary Ta-N chemical system includes several compounds with notable prospects in microelectronics, solar energy harvesting, and catalysis. Among these, metallic TaN and semiconducting Ta3N5 have garnered significant interest, in part due to their synthetic accessibility. However, tantalum sesquinitride (Ta2N3) possesses an intermediate composition and largely unknown physical properties owing to its metastable nature. Herein, Ta2N3 is directly deposited by reactive magnetron sputtering and its optoelectronic properties are characterized. Combining these results with density functional theory provides insights into the critical role of oxygen in both synthesis and electronic structure. While the inclusion of oxygen in the process gas is critical to Ta2N3 formation, the resulting oxygen incorporation in structural vacancies drastically modifies the free electron concentration in the as-grown material, thus leading to a semiconducting character with a 1.9 eV bandgap. Reducing the oxygen impurity concentration via post-synthetic ammonia annealing increases the conductivity by seven orders of magnitude and yields the metallic characteristics of a degenerate semiconductor, consistent with theoretical predictions. Thus, this inverse oxygen doping approach - by which the carrier concentration is reduced by the oxygen impurity - offers a unique opportunity to tailor the optoelectronic properties of Ta2N3 for applications ranging from photochemical energy conversion to advanced photonics.

10.
Zhonghua Wai Ke Za Zhi ; 48(21): 1637-41, 2010 Nov 01.
Artículo en Zh | MEDLINE | ID: mdl-21211259

RESUMEN

OBJECTIVE: To compare the therapeutic effect of posterior lumbar interbody fusion by single and double B-Twin expandable spinal spacer with micro endoscopic discectomy (MED) for lumbar intervertebral disc protrusion accompanying degenerative instability. METHODS: From March 2006 to May 2008, 45 patients with lumbar intervertebral disc protrusion accompanying degenerative instability were admitted and managed with posterior lumbar interbody fusion by B-Twin expandable spinal spacer with MED. The patients were randomly assigned to treatment with single B-Twin (Single group, n = 24) or double B-Twin (Double group, n = 21). There were 16 males and 8 females, with an average age of 45.5 years (43 - 60 years) in Single group; 13 males and 8 females, with an average age of 43.7 years (44-61 years) in Double group. All the cases suffered from only one level disc protrusion, L(3-4) 2 cases, L(4-5) 29 cases and L5-S1 14 cases. Clinical outcomes were evaluated with surgical time, blood loss, visual analogue scale (VAS) scores preoperatively, 1, 3, 6 month postoperatively. Oswestry disability questionnaire (ODI) of the preoperative, 1 month postoperative, and latest follow-up and the disk space heights. RESULTS: Forty three patients were followed-up for 1 to 3 years after surgery. The mean surgical time of Double group was longer than Single group [(152 ± 32) min vs. (91 ± 15) min, P < 0.01]. The average blood loss in Double group was more than that in Single group [(146 ± 73) ml vs. (95 ± 58) ml, P < 0.01]. The mean time of hospital stay in Single group was similar to that in Double group [(11.0 ± 3.2) d vs. (10.9 ± 3.3) d, P > 0.05]. Both groups could keep the disk space heights till the last follow-up [(7.7 ± 1.8) mm vs. (8.5 ± 1.7) mm]. In the 6 months follow-up post operation, the VAS score decreased from (8.1 ± 1.8) to (2.0 ± 1.0) in Single group, and (8.1 ± 1.9) to (2.1 ± 1.0) in Double group. At the last follow-up, the ODI decreased from (36 ± 7)% to (10 ± 4)% in Single group and (37 ± 6)% to (9 ± 4)% in Double group, but there was no significant difference between the two groups (P > 0.05). All the cases achieved fusion at the last follow-up, 3 patients in Single group and 2 patients in Double group suffered from intractable low back pain. One of the fins broke in one patient without any uncomfortable feeling. CONCLUSIONS: Compared with the management of lumbar intervertebral disc protrusion accompanying degenerative instability by double B-Twin expandable spinal spacer with micro endoscopic discectomy, the single B-twin can get similar clinical outcomes, but shorter surgical time, less blood loss and less medical costs.


Asunto(s)
Desplazamiento del Disco Intervertebral/cirugía , Vértebras Lumbares , Fusión Vertebral/métodos , Adulto , Endoscopía , Femenino , Estudios de Seguimiento , Humanos , Masculino , Persona de Mediana Edad , Estudios Prospectivos , Resultado del Tratamiento
11.
Chemphyschem ; 9(15): 2221-9, 2008 Oct 24.
Artículo en Inglés | MEDLINE | ID: mdl-18821540

RESUMEN

The interplay between excited-state charge and proton transfer reactions in protic solvents is investigated in a series of 7-azaindole (7AI) derivatives: 3-cyano-7-azaindole (3CNAI), 5-cyano-7-azaindole (5CNAI), 3,5-dicyano-7-azaindole (3,5CNAI) and dicyanoethenyl-7-azaindole (DiCNAI). Similar to 7AI, 3CNAI and 3,5CNAI undergo methanol catalyzed excited-state double proton transfer (ESDPT), resulting in dual (normal and proton transfer) emission. Conversely, ESDPT is prohibited for 5CNAI and DiCNAI in methanol, as supported by a unique normal emission with high quantum efficiency. Instead, the normal emission undergoes prominent solvatochromism. Detailed relaxation dynamics and temperature dependent studies are carried out. The results conclude that significant excited-state charge transfer (ESCT) takes place for both 5CNAI and DiCNAI. The charge-transfer specie possesses a different dipole moment from that of the proton-transfer tautomer species. Upon reaching the equilibrium polarization, there exists a solvent-polarity induced barrier during the proton-transfer tautomerization, and ESDPT is prohibited for 5CNAI and DiCNAI during the excited-state lifespan. The result is remarkably different from 7AI, which is also unique among most excited-state charge/proton transfer coupled systems studied to date.


Asunto(s)
Compuestos Aza/química , Indoles/química , Nitrilos/química , Compuestos Aza/síntesis química , Enlace de Hidrógeno , Indoles/síntesis química , Modelos Químicos , Estructura Molecular , Nitrilos/síntesis química , Protones , Solventes/química , Estereoisomerismo
12.
ACS Appl Mater Interfaces ; 10(13): 10627-10633, 2018 Apr 04.
Artículo en Inglés | MEDLINE | ID: mdl-29489326

RESUMEN

To understand functional roles of constituent elements in ternary metal oxide photoanodes, essential photoelectrochemical (PEC) properties are systematically analyzed on a series of copper vanadate compounds with different Cu:V elemental ratios. Homogeneous and highly continuous thin films of ß-Cu2V2O7, γ-Cu3V2O8, Cu11V6O26, and Cu5V2O10 are grown via reactive co-sputtering and their performance characteristics for the light-driven oxygen evolution reaction are evaluated. All four compounds have similar bandgaps in the range of 1.83-2.03 eV, though Cu-rich phases exhibit stronger optical absorption and higher charge separation efficiencies. Transient photocurrent analysis reveals a reduction of surface catalytic activity with increasing Cu:V elemental ratio due to competitive charge recombination at Cu-related surface states. This comprehensive analysis of PEC functionalities-including photon absorption, carrier separation, and heterogeneous charge transfer-informs strategies for improving PEC activity in the copper vanadate materials system and provides insights that may aid discovery, design, and engineering of new photoelectrode materials.

13.
Org Lett ; 9(25): 5287-90, 2007 Dec 06.
Artículo en Inglés | MEDLINE | ID: mdl-18001048

RESUMEN

A new photochromic colorant with an oxazabicyclic moiety has been synthesized by an efficient method. It turns pale red upon UV irradiation and undergoes reverse reaction while being heated. This work may open an exciting new avenue for future development of the photochromic dyes with novel molecular structures.

14.
Artículo en Inglés | MEDLINE | ID: mdl-29430255

RESUMEN

The present study aimed to investigate the therapeutic effects of the Chinese herbal medicine Yin Zhi Huang soup (YZS) in an experimental autoimmune prostatitis (EAP) rat model. In total, 48 rats were randomly divided into the following four groups (n = 12/group): saline group, pathological model group, Qianlietai group, and YZS group. We determined the average wet weight of the prostate tissue, the ratio of the wet weight of the prostate tissue to body weight, tumor necrosis factor-alpha (TNF-α) levels in the blood serum, the expression of inducible nitric oxide synthase (iNOS) in the rats' prostate tissues, and the pathological changes in the prostate tissue using light microscopy. YZS reduced the rats' prostate wet weight, the ratio of the prostate wet weight to body weight, and TNF-α levels in the blood serum and inhibited the expression of iNOS in the rats' prostate tissues (P < 0.05). Following YZS treatment, the pathological changes in the rats' prostates were improved compared with those in the model group (P < 0.05). Furthermore, YZS treatment reduced inflammatory changes in the prostate tissue. It also significantly suppressed proinflammatory cytokines, such as TNF-α, and chemokines, such as iNOS, in the rat model of EAP.

15.
Adv Mater ; 29(44)2017 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-29024072

RESUMEN

The emerging molybdenum disulfide (MoS2 ) offers intriguing possibilities for realizing a transformative new catalyst for driving the hydrogen evolution reaction (HER). However, the trade-off between catalytic activity and long-term stability represents a formidable challenge and has not been extensively addressed. This study reports that metastable and temperature-sensitive chemically exfoliated MoS2 (ce-MoS2 ) can be made into electrochemically stable (5000 cycles), and thermally robust (300 °C) while maintaining synthetic scalability and excellent catalytic activity through physical-transformation into 3D structurally deformed nanostructures. The dimensional transition enabled by a high throughput electrohydrodynamic process provides highly accessible, and electrochemically active surface area and facilitates efficient transport across various interfaces. Meanwhile, the hierarchically strained morphology is found to improve electronic coupling between active sites and current collecting substrates without the need for selective engineering the electronically heterogeneous interfaces. Specifically, the synergistic combination of high strain load stemmed from capillarity-induced-self-crumpling and sulfur (S) vacancies intrinsic to chemical exfoliation enables simultaneous modulation of active site density and intrinsic HER activity regardless of continuous operation or elevated temperature. These results provide new insights into how catalytic activity, electrochemical-, and thermal stability can be concurrently enhanced through the physical transformation that is reminiscent of nature, in which properties of biological materials emerge from evolved dimensional transitions.

16.
Artículo en Zh | MEDLINE | ID: mdl-18773805

RESUMEN

OBJECTIVE: To investigate the clinical application and efficacy of lumbar vertebral canal expansion with preservation of posterior ligaments complex, and to study its biomechanical properties. METHODS: Eight fresh lumbosacral cadaveric samples were divided into 3 groups. In group A, 8 intact lumbosacral cadaveric samples were used for biomechanical test. In group B, L3-5 laminectomy were, after the test in group A, performed and the posterior ligaments complex was preserved. In group C, the posterior ligaments complex was excised after the test in group B. In all 3 groups, the axial compression test, three-point bending test and torsional test were conducted. From June 2000 to June 2006, 309 patients (152 males and 157 females, aged 20-80 years with the average of 57.2 ) with lumbar canal stenosis received operation of the lumbar vertebral canal expansion with preservation of posterior ligaments complex. The course of disease was 3 months to 41 years. There were 55 patients suffering from pure lumbar canal stenosis, and 254 from lumbar canal stenosis combined with lumbar disc herniation, among which 105 were at L4,5 level, 56 at L4-S1 level, 86 at L5, S1 level, and 7 at L2,3 level. The therapeutic effect was assessed based on the JOA low back pain scoring system, the satisfaction degree of patient and radiographical observation. RESULTS: The axial compression test was performed. In the position of forward bending, stress, strain and axial displacement were smaller in groups A, B than those in group C, and axial stiffness in groups A, B was higher than those in group C, and the difference was significant (P < 0.01). In the position of backward extension, there was no significant difference among 3 groups (P > 0.05). Concerning the three-point bending test, under the same bending moment, there was a significant difference in deflection, dip and bending rigidity between group A and group C, and also between group B and group C (P < 0.01), but no significant difference between group A and group B (P> 0.05). In the torsional test, under the same torsional angle, the torque in group B was bigger than that in group C (P < 0.01). Under the same torque, the torsional angle in group B was smaller than that in group C (P < 0.01), and the torsional stiffness in group B was higher than that in group C (P < 0.01). The complications included 7 cases of distraction of nerve root, 5 leakage of cerebrospinal fluid and 4 wound infection. All complications were treated and restored completely. All patients were followed up for 1-7 years. According to the JOA low back pain scoring system, the improvement rate averaged 86.0%. Of all the 309 cases, 163 were excellent, 112 good, 34 fair, and the choiceness rate was 89%. The satisfaction rate of patient was 87%. There was no radiographic vertebral instability postoperatively. CONCLUSION: The lumbar vertebral canal expansion with preservation of posterior ligaments complex is conducive to maintaining the stability of lumbar spine and have good clinical outcomes.


Asunto(s)
Descompresión Quirúrgica/métodos , Ligamentos Longitudinales/anatomía & histología , Vértebras Lumbares/anatomía & histología , Estenosis Espinal/fisiopatología , Adulto , Anciano , Anciano de 80 o más Años , Fenómenos Biomecánicos , Femenino , Humanos , Ligamentos Longitudinales/cirugía , Vértebras Lumbares/cirugía , Masculino , Persona de Mediana Edad , Fusión Vertebral , Estenosis Espinal/cirugía
17.
Dalton Trans ; (48): 6901-11, 2008 Dec 28.
Artículo en Inglés | MEDLINE | ID: mdl-19050776

RESUMEN

A new series of mono-cyclometalated Pt(II) complexes 1-4 with chelating 2-pyridyl hexafluoropropoxide as the ancillary ligand were synthesized. Single crystal X-ray diffraction studies were examined, giving evidence for the occurrence of pi pi stacking between the cyclometalated ligands, but a lack of intermolecular Pt ... Pt interaction. Among these complexes, the benzo[h]quinoline analogue 2a shows the greatest degree of pi pi stacking, which is also confirmed by the observation of additional, large Stokes shifted emission attributed to the aggregated counterparts in solid thin film. All these Pt(II) complexes are highly emissive in solid state, whereas except for 4-phenylquinazoline analogues 4a and 4b, complexes 1-3 in solution are subject to dominant radiationless deactivation induced, in part, by the solvent collision to the square planar Pt(II) framework. Electroluminescent OLEDs employing 2-phenylpyridine analogue 1b as the dopants were fabricated, rendering satisfactory performance data suited for future improvement.


Asunto(s)
Quelantes/química , Compuestos Organometálicos/química , Compuestos Organoplatinos/química , Platino (Metal)/química , Absorción , Electroquímica , Ligandos , Luminiscencia , Piridinas/química , Espectrofotometría Ultravioleta , Temperatura
18.
Inorg Chem ; 46(26): 11202-12, 2007 Dec 24.
Artículo en Inglés | MEDLINE | ID: mdl-18027932

RESUMEN

A new Pt(II) dichloride complex [Pt(fppzH)Cl2] (1), in which fppzH = 3-(trifluoromethyl)-5-(2-pyridyl)pyrazole, was prepared by the treatment of a pyridylpyrazole chelate fppzH with K2PtCl4 in aqueous HCl solution. Complex 1 could further react with its parent pyrazole (pzH), 3,5-dimethylpyrazole (dmpzH), or 3,5-di-tert-butylpyrazole (dbpzH) to afford the monometallic [Pt(fppz)(pzH)Cl] (2), [Pt(fppz)(dmpzH)Cl] (3), [Pt(fppz)(dmpzH)2]Cl (4), or two structural isomers with formula [Pt(fppz)(dbpzH)Cl] (5a,b). Single-crystal X-ray diffraction studies of 2, 4, and 5a,b revealed a square planar Pt(II) framework, among which a strong interligand hydrogen bonding occurred between fppz and pzH ligands in 2. This interligand H-bonding is replaced by dual N-H...Cl interaction in 4 and both intermolecular N-H...O (with THF solvate) and N-H...Cl interaction in 5a,b, respectively; the latter are attributed to the bulky tert-butyl substituents that force the dbpzH ligand to adopt the perpendicular arrangement. Furthermore, complex 2 underwent rapid deprotonation in basic media to afford two isomeric complexes with formula [Pt(fppz)(mu-pz)]2 (6a,b), which are related to each other according to the spatial orientation of the fppz chelates, i.e., trans- and cis-isomerism. Similar reaction exerted on 3 afforded isomers 7a,b. Both 6a,b (7a,b) are essentially nonemissive in room-temperature fluid state but afford strong blue phosphorescence in solid state prepared via either vacuum-deposited thin film or 77 K CH2Cl2 matrix. As also supported by the computational approaches, the nature of emission has been assigned to be ligand-centered triplet pipi* mixed with certain metal-to-ligand charge-transfer character.

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