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1.
BMC Geriatr ; 24(1): 558, 2024 Jun 26.
Artículo en Inglés | MEDLINE | ID: mdl-38918715

RESUMEN

BACKGROUND: Quantifying the informal caregiver burden is important for understanding the risk factors associated with caregiver overload and for evaluating the effectiveness of services provided in Long-term Care (LTC). OBJECTIVE: This study aimed to develop and validate a Caregiver Strain Index (CSI)-based score for quantifying the informal caregiver burden, while the original dataset did not fully cover evaluation items commonly included in international assessments. Subsequently, we utilized the CSI-based score to pinpoint key caregiver burden risk factors, examine the initial timing of LTC services adoption, and assess the impact of LTC services on reducing caregiver burden. METHODS: The study analyzed over 28,000 LTC cases in Southern Taiwan from August 2019 to December 2022. Through multiple regression analysis, we identified significant risk factors associated with caregiver burden and examined changes in this burden after utilizing various services. Survival analysis was employed to explore the relationship between adopting the first LTC services and varying levels of caregiver burden. RESULTS: We identified 126 significant risk factors for caregiver burden. The most critical factors included caregiving for other disabled family members or children under the age of three (ß = 0.74, p < 0.001), the employment status of the caregiver (ß = 0.30-0.53, p < 0.001), the frailty of the care recipient (ß = 0.28-0.31, p < 0.001), and the behavioral symptoms of dementia in care recipients (ß = 0.28-2.60, p < 0.05). Generally, caregivers facing higher burdens sought LTC services earlier, and providing home care services alleviated the caregiver's burden. CONCLUSION: This comprehensive study suggests policy refinements to recognize high-risk caregivers better early and provide timely support to improve the overall well-being of both informal caregivers and care recipients.


Asunto(s)
Carga del Cuidador , Cuidadores , Cuidados a Largo Plazo , Humanos , Taiwán/epidemiología , Masculino , Femenino , Carga del Cuidador/psicología , Anciano , Cuidadores/psicología , Cuidados a Largo Plazo/métodos , Persona de Mediana Edad , Factores de Riesgo , Anciano de 80 o más Años , Estrés Psicológico/psicología , Estrés Psicológico/epidemiología , Adulto
2.
Environ Sci Technol ; 52(11): 6518-6525, 2018 06 05.
Artículo en Inglés | MEDLINE | ID: mdl-29727187

RESUMEN

The development of efficient heterogeneous Fenton catalysts is mainly by "trial-and-error" concept and the factor determining H2O2 activation remains elusive. In this work, we demonstrate that suitable facet exposure to elongate O-O bond in H2O2 is the key parameter determining the Fenton catalyst's activity. CuFeO2 nanocubes and nanoplates with different surface facets of {110} and {012} are used to compare the effect of exposed facets on Fenton activity. The results indicate that ofloxacin (OFX) degradation rate by CuFeO2 {012} is four times faster than that of CuFeO2 {110} (0.0408 vs 0.0101 min-1). In CuFeO2 {012}-H2O2 system, OFX is completely removed at a pH range 3.2-10.1. The experimental results and theoretical simulations show that •OH is preferentially formed from the reduction of absorbed H2O2 by electron from CuFeO2 {012} due to suitable elongation of O-O (1.472 Å) bond length in H2O2. By contrast, the O-O bond length is elongated from 1.468 to 3.290 Å by CuFeO2 {110} facet, H2O2 tends to be dissociated into -OH group and passivates {110} facet. Besides, the new formed ≡Fe2+* on CuFeO2 {012} facet can accelerate the redox cycle of Cu and Fe species, leading to excellent long-term stability of CuFeO2 nanoplates.


Asunto(s)
Contaminantes Ambientales , Peróxido de Hidrógeno , Catálisis , Ofloxacino , Oxidación-Reducción
3.
4.
Cancers (Basel) ; 15(18)2023 Sep 16.
Artículo en Inglés | MEDLINE | ID: mdl-37760567

RESUMEN

BACKGROUND: Long-term care (LTC) service demands among cancer patients are significantly understudied, leading to gaps in healthcare resource allocation and policymaking. OBJECTIVE: This study aimed to predict LTC service demands for cancer patients and identify the crucial factors. METHODS: 3333 cases of cancers were included. We further developed two specialized prediction models: a Unified Prediction Model (UPM) and a Category-Specific Prediction Model (CSPM). The UPM offered generalized forecasts by treating all services as identical, while the CSPM built individual predictive models for each specific service type. Sensitivity analysis was also conducted to find optimal usage cutoff points for determining the usage and non-usage cases. RESULTS: Service usage differences in lung, liver, brain, and pancreatic cancers were significant. For the UPM, the top 20 performance model cutoff points were adopted, such as through Logistic Regression (LR), Quadratic Discriminant Analysis (QDA), and XGBoost (XGB), achieving an AUROC range of 0.707 to 0.728. The CSPM demonstrated performance with an AUROC ranging from 0.777 to 0.837 for the top five most frequently used services. The most critical predictive factors were the types of cancer, patients' age and female caregivers, and specific health needs. CONCLUSION: The results of our study provide valuable information for healthcare decisions, resource allocation optimization, and personalized long-term care usage for cancer patients.

5.
Zhongguo Gu Shang ; 35(1): 80-4, 2022 Jan 25.
Artículo en Zh | MEDLINE | ID: mdl-35130605

RESUMEN

OBJECTIVE: To explore the clinical application of lockedge suspension combined with three steel wires vertical fixation in comminuted fracture of inferior pole of patella. METHODS: From August 2016 to May 2019, 23 patients with comminuted fracture of the lower pole of the patella, including 14 males and 9 females, were treated with lockedge suspension combined with three steel wires vertical fixation. The age ranged from 34 to 68 (55.0±1.2) years. One year after operation, the pain and function were evaluated by pain visual analogue scale(VAS) and knee flexion and extension range of motion, and the clinical efficacy was evaluated by Lysholm knee score standard. RESULTS: All 23 patients were followed up for 12 to 14, with a mean of(13.0±0.5) months. One patient had skin irritation by the tail of the steel wire, and the rest had no postoperative complications such as incision infection, internal fixation loosening and fracture displacement. The fractures of 23 patients were healed, and the healing time was 10 to 14 weeks with a mean of(12.0±1.1) weeks. The VAS score decreased from 7.96±0.93 before operation to 0.83±0.65 one year after operation. The range of knee flexion and extension activities increased from(20.30±8.69) ° before operation to 1 year after operation(127.39±6.55) °. Lysholm knee score increased from 18.48±4.00 before operation to 96.09±4.91 one year after operation(P<0.05). CONCLUSION: The treatment of comminuted fracture of the lower pole of patella by lockedge suspension combined with three steel wires vertical fixation has reliable fixation and high fracture healing rate. It can meet the requirements of rapid rehabilitation and functional exercise, and the early clinical effect is satisfactory.


Asunto(s)
Fracturas Óseas , Fracturas Conminutas , Adulto , Anciano , Hilos Ortopédicos , Femenino , Fijación Interna de Fracturas , Fracturas Óseas/cirugía , Fracturas Conminutas/cirugía , Humanos , Masculino , Persona de Mediana Edad , Rótula/cirugía , Acero , Resultado del Tratamiento
6.
Chemosphere ; 294: 133743, 2022 May.
Artículo en Inglés | MEDLINE | ID: mdl-35093424

RESUMEN

In Fenton or Fenton-like processes, the key step is to catalyze H2O2 and produce highly reactive OH radicals. More efforts are then focus on designing efficient heterogeneous Fenton catalysts by activating H2O2 to generate OH at the highest possible steady state concentration. In this study, using the antibiotic ofloxacin as target organic pollutant, we firstly demonstrate a point of view for improving OH utilization efficiency by regulating surface chemical reactions to minimizing its migration distance to the target pollutant. C doped g-C3N4 incorporated CuFeO2 (CCN/CuFeO2) exhibited almost ten times higher ofloxacin degradation rate constant than our previously reported CuFeO2 {012} catalyst (0.1634 vs 0.0179 min-1). Since similar amount of OH was generated, the different inhibition effect of tert-butyl alcohol and nitrobenzene on the ofloxacin degradation confirmed that the much-enhanced ofloxacin degradation was attributed to the surface Fenton reaction process. According to XPS and EXAFS characterization, the C-O-Cu bond between g-C3N4 and CuFeO2 established a closed-circuit surface Fenton reaction mechanism. H2O2 was adsorbed and decomposed into OH/O2- over ≡Cu + site in CuFeO2. The successful construction of CCN/CuFeO2 creates a negative surface potential and benefits the enrichment of target antibiotics from water, which greatly reduces the migration distance of OH/O2•- to adjacent pollutant and then increases the OH/O2- utilization efficiency by avoiding the unwanted quenching. Hence, CCN/CuFeO2 possesses superior Fenton catalytic activity and long-term stability.


Asunto(s)
Peróxido de Hidrógeno , Nanocompuestos , Antibacterianos , Catálisis , Ofloxacino
7.
Sci Rep ; 12(1): 9668, 2022 06 11.
Artículo en Inglés | MEDLINE | ID: mdl-35690597

RESUMEN

Microscopy by Achromatic X-rays With Emission of Laminar Light (MAXWELL) is a new X-ray/visible technique with attractive characteristics including isotropic resolution in all directions, large-volume imaging and high throughput. An ultrathin, laminar X-ray beam produced by a Wolter type I mirror irradiates the sample stimulating the emission of visible light by scintillating nanoparticles, captured by an optical system. Three-dimensional (3D) images are obtained by scanning the specimen with respect to the laminar beam. We implemented and tested the technique with a high-brightness undulator at SPring-8, demonstrating its validity for a variety of specimens. This work was performed under the Synchrotrons for Neuroscience-an Asia-Pacific Strategic Enterprise (SYNAPSE) collaboration.


Asunto(s)
Microscopía , Sincrotrones , Imagenología Tridimensional , Luz , Microscopía/métodos , Tomografía Computarizada por Rayos X/métodos , Rayos X
8.
Zhongguo Gu Shang ; 34(9): 851-5, 2021 Sep 25.
Artículo en Zh | MEDLINE | ID: mdl-34569211

RESUMEN

OBJECTIVE: To explore clinical effect of arthroscopic meniscus tear strapping suture by rotator cuff suture threader. METHODS: Forty patients with meniscus tear injury admitted from July 2015 to May 2019, including 27 males and 13 females, aged from 20 to 55 years old with an average of (36.0±1.4) years old. Menisci laceration was sutured with rotator cuff suture thread under arthroscopy. Postoperative complication was observed, Lysholm knee joint score before and after operation at 12 months were used to evaluate clinical effects, visual analogue scale (VAS) and range of knee flexion and extension were applied to evaluate recovery of pain and function. RESULTS: All patients were followed up from 12 to 15 months with an average of (12.6±0.7) months.No complication such as joint effusion, suture failure occurred. Two patients occurred mild pain after activity without clinical physical abnormality, and 1 patient manifested moderate pain with joint space tenderness, the other rest without abnormal. Lysholm knee joint score was increased from (49.55±1.21) preoperatively to (98.95±0.42) at 12 months after operation, VAS score decreased from (5.18±0.78)preoperatively to (1.03±0.77) at 12 months after operation, and range of knee joint flexion and extension activity increased from (50.63±9.20)°preoperatively to (130.38±4.99)°after operation, and there were statistical differences in Lysholm knee joint score, VAS and range of knee joint flexion and extension activity (P< 0.05). CONCLUSION: Arthroscopic strapping suture by rotator cuff suture threading device applies to most meniscus injuries, including medial meniscus posterior horn tears, lateral meniscus body tears and lateral meniscus posterior horn tears. This technique meets the need of full-internal meniscus suture without specialmeniscus suture, and has advantages of convenient operation, less complications and good postoperative function.


Asunto(s)
Lesiones del Manguito de los Rotadores , Lesiones de Menisco Tibial , Adulto , Artroscopía , Femenino , Humanos , Masculino , Meniscos Tibiales/cirugía , Persona de Mediana Edad , Manguito de los Rotadores , Lesiones del Manguito de los Rotadores/cirugía , Técnicas de Sutura , Suturas/efectos adversos , Lesiones de Menisco Tibial/cirugía , Resultado del Tratamiento , Adulto Joven
9.
J Nanosci Nanotechnol ; 10(5): 3155-61, 2010 May.
Artículo en Inglés | MEDLINE | ID: mdl-20358913

RESUMEN

In the present study, pure TiO2 and hybrid TiO2/CNTs nanomaterials are prepared by sol gel technique. Post heat treatment is performed at 600, 800, and 1000 degrees C, respectively. The structural characterizations are performed by field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction and synchrotron X-ray absorption spectroscopy techniques. Experimental results show that anatase to rutile transformation can be observed for pure TiO2 nanomaterials after heat treatment at 800 degrees C. The anatase to rutile transformation is inhibited by carbon nanotubes, and therefore only anatase phases for TiO2 nanomaterials can be observed in the hybrid nanomaterials. The 600 degrees C hybrid nanomaterials show a microstructure with CNTs covered by continuous TiO2 films of numerous small nanoparticles. After applying heat treatment on the hybrid nanomaterials at 1000 degrees C, only TiO2 nanoparticles adhere individually to the uncovered CNTs. Though all hybrid nanomaterials exhibit anatase TiO2, synchrotron X-ray absorption spectra investigations reveal that hybrid TiO2/CNTs exhibit different electronic properties as compared to those of pure TiO2 nanomaterials.

10.
Nanoscale ; 12(30): 16262-16269, 2020 Aug 14.
Artículo en Inglés | MEDLINE | ID: mdl-32716460

RESUMEN

A novel insertable and pseudocapacitive Li+ ion material for highly ordered layered montmorillonite/carbon is explored in the present study. The commercially available protonated montmorillonite and 3,3'-diaminobenzidine act as starting materials to synthesize the layered material via hydrothermal intercalation, oxidative polymerization and carbonization. This method of preparing montmorillonite/carbon nanocomposite exhibits several advantages. To be specific, raw materials are low cost and naturally abundant; the montmorillonite can undergo proton exchange easily to form a permutable proton-type material, and the protons in the layered nanocomposite can be directly substituted by the polymerizable molecules (e.g., 3,3'-diaminobenzidine). Accordingly, a sheet-like montmorillonite/carbon layered nanocomposite is achieved with the carbon stacking on the montmorillonite substrate for the intercalation behavior. As revealed from the electrochemical results, montmorillonite/carbon nanocomposite can deliver a high reversible capacity of 1432 mA h g-1 at 50 mA g-1 and superior rate capacity of 920 mA h g-1 at 10 000 mA g-1 for the lithium ion battery. Furthermore, the full cell with LiFePO4 as cathode and montmorillonite/carbon as anode maintains 94% capacity retention over 50 cycles as well as high coulombic efficiency.

11.
Sci Total Environ ; 723: 138144, 2020 Jun 25.
Artículo en Inglés | MEDLINE | ID: mdl-32224407

RESUMEN

An efficient strategy for enhancing iron efficiency in heterogeneous Fenton reaction via the pyrolysis of ferrocene chemically modified sepiolite (Sep) was proposed in this study. Highly dispersed FeC6 on sepiolite (Fe-Dis@Sep) was synthesized as an efficient photo-Fenton catalyst for the visible light degradation of ofloxacin (OFX). It exhibits an excellent Fenton activity and stability towards OFX degradation. The pseudo-first order reaction rate constant of Fe-Dis@Sep was 5.1-fold higher than that of the supported catalyst with aggregated iron oxides prepared by traditional impregnation method (Fe-Agg@Sep). Based on TEM images and density functional theory (DFT) calculation, the enhanced Fenton activity of Fe-Dis@Sep was attributed to the unique incorporation of FeC6 on Sep via Si-O-C-Fe bond which not only favor the high dispersion of FeC6 with an electron deficiency but also promote Fe(III) to Fe(II) cycle via the formation of surface Fe-H2O2 complex. OH and O2- were identified as active species for OFX degradation in Fe-Dis@Sep-H2O2-Vis system. 98.7% of F and 97.0% of N in OFX was converted into F- and NO3- with a TOC removal efficiency of 89.35%. The possible degradation pathway of OFX was also proposed according to HPLC-MS results. Finally, the Fenton reaction mechanism over Fe-Dis@Sep was discussed.


Asunto(s)
Compuestos Férricos , Ofloxacino , Catálisis , Electrones , Peróxido de Hidrógeno , Silicatos de Magnesio , Oxidación-Reducción
12.
Chemosphere ; 236: 124367, 2019 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-31325831

RESUMEN

In this study, the highly dispersed ß-FeOOH on palygorskite (H-ß-FeOOH/PAL) was prepared and investigated as Fenton catalyst for H2O2 activation towards metronidazole (MTZ). Based on electron spin resonance and probe techniques, hydroxyl radicles (•OH) as main reactive oxygen species was confirmed, and much more •OH were generated over H-ß-FeOOH/PAL than T-ß-FeOOH/PAL using traditional impregnation method. The enhanced Fe(III) to Fe(II) cycle due to the highly dispersed ß-FeOOH leads to the fast degradation of metronidazole over H-ß-FeOOH/PAL. 92.8% of MTZ degradation efficiency was achieved within 180 min by adding 17 mmol/L H2O2 and 40 mg/L of H-ß-FeOOH/PAL at pH 6.0. The bacterial cytotoxicity during MTZ degradation process also decreased with reaction time and achieved zero at 66 min, indicating MTZ was not only efficiently degraded but also safely transformed. Besides, the possible MTZ degradation pathway was further proposed based on the intermediates identified by HPLC-MS.


Asunto(s)
Compuestos Férricos/química , Peróxido de Hidrógeno/química , Metronidazol/uso terapéutico , Metronidazol/farmacología
13.
Zhongguo Gu Shang ; 31(9): 790-793, 2018 Sep 25.
Artículo en Zh | MEDLINE | ID: mdl-30332868

RESUMEN

OBJECTIVE: To explore the clinical effect of modified Metaizeau's technique for radial neck fractures of Judet II or IV in children, summarizing the value of clinical application. METHODS: From May 2014 to March 2017, 32 children of Judet III or IV radial neck fractures were treated with percutaneous Kirschner wire poking reduction and closed reduction with elastic intramedullary nailing fixation, including 21 boys and 11 girls, aged from 5.7 to 10.6 years old with a mean of 7.2 years old. The modified An-Morrey functional rating index were used to evaluate elbow range of motion, myodynamia, stability, and pain preoperatively and 1 year postoperatively in all the patients. RESULTS: All patients were available for an average follow-up from 12 to 15 months. No complications such as incision infection, wire or nail tail irritation and avascular necrosis of radial head and epiphyses was occurred. The fracture achieved solid healing at 8 to 10 weeks after operation. The modified An and Morrey functional score improved from 58.69±5.80 before operation to 99.13±1.79 at 1 year after operation, there was obvious difference of scores between preoperative and postoperative at 1 year. CONCLUSIONS: Modified Metaizeau's technique is a reliable and good treatment for Judet III or IV radial neck fractures in children, which has advantages of few complication, minimal invasion, quick fracture union and good recovery of elbow joint.


Asunto(s)
Clavos Ortopédicos , Fracturas del Radio , Niño , Preescolar , Codo , Epífisis , Femenino , Humanos , Masculino , Rango del Movimiento Articular , Estudios Retrospectivos , Resultado del Tratamiento
14.
J Nanosci Nanotechnol ; 7(9): 3081-8, 2007 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-18019132

RESUMEN

Several aromatic compounds derived from benzene by its annelation (naphthalene, anthracene, phenanthrene, pyrene) and exocyclic substitution (e.g., nitrobenzene, dinitrobenzenes, trinitrobenzene, chlorobenzene, N,N-dimethylaniline, and others) and endocyclic substitution (pyridine, quinoline, isoquinoline) efficiently sorbed on multi-walled carbon nanotubes (MWCNTs). Equilibrium constants for the sorption process have been determined. Computations of the energy of formation were performed for surface complexes of those arenes on single-walled carbon nanotubes (SWCNTs). Formation energies of those complexes were correlated against the experimental equilibrium constants. The latter were also correlated against calculated LUMO energy of the arenes. Solely, limited tendencies to the linearity could be observed. The analysis of the results of the correlations indicated that the arenes acting as the charge acceptors formed stronger complexes than arenes with a high electron density in the molecular orbital, for instance, N, N-dimethylaniline. The area of the arene--SWCNT contact was very essential for the complexation. The proximity of the HOMO orbital of SWCNT and LUMO of the arene was another essential factor. Bulky substituents in the arene molecules obscured their efficient contact with SWCNT.


Asunto(s)
Química Orgánica/métodos , Nanotecnología/métodos , Nanotubos de Carbono/química , Nanotubos/química , Compuestos de Anilina/química , Benceno/química , Cinética , Microscopía Electrónica de Transmisión , Modelos Químicos , Nanoestructuras/química , Espectrofotometría , Espectrofotometría Ultravioleta/métodos , Propiedades de Superficie , Temperatura , Factores de Tiempo
15.
Sci Rep ; 7: 40185, 2017 01 05.
Artículo en Inglés | MEDLINE | ID: mdl-28054644

RESUMEN

Although pressure therapy (PT) represents the standard care for prevention and treatment of hypertrophic scar (HS) from burns, its practice is largely based on empirical evidence and its effectiveness remains controversial. To clarify the effect of PT (15-25 mmHg) for HS, we performed the systematic review and meta-analysis. Several electronic databases were screened to identify related randomized controlled trials (RCTs). 12 RCTs involving 710 patients with 761 HS resulting from burn injuries were included. Compared with non/low-PT, cases treated with PT (15-25 mmHg) showed significant differences in Vancouver Scar Scale score (MD = -0.58, 95% CI = -0.78--0.37), thickness (SMD = -0.25, 95% CI = -0.40--0.11), brightness (MD = 2.00, 95% CI = 0.59-3.42), redness (MD = -0.79, 95% CI = -1.52--0.07), pigmentation (MD = -0.16, 95% CI = -0.32--0.00) and hardness (SMD = -0.65, 95% CI = -1.07--0.23). However, there was no difference in vascularity (MD = 0.03, 95% CI = -0.43-0.48). Our analysis indicated that patients with HS who were managed with PT (15-25 mmHg) showed significant improvements. Due to limitations, more large and well-designed studies are needed to confirm our findings and the side-effects of the PT may also need to be evaluated.


Asunto(s)
Quemaduras/terapia , Cicatriz Hipertrófica/prevención & control , Presión Hidrostática , Cicatriz Hipertrófica/patología , Humanos , Ensayos Clínicos Controlados Aleatorios como Asunto , Resultado del Tratamiento
16.
J Nanosci Nanotechnol ; 5(12): 2121-7, 2005 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-16430150

RESUMEN

As proven by the UV-VIS, micro-Raman spectroscopies, differential scanning calorimetry, beta-carotene, lycopene, retinoic acid, and retinol adsorbed on the surface of single-walled carbon nanotubes (SWCNT) form electron donor-acceptor (EDA) complexes. The rate of the adsorption of carotenoids is estimated as the rate of decrease in their concentration in solution followed the exponential curve equation. The rate of the adsorption decreased with the chain length of the guest capable sorption on the surface and steric effect of the terminals in the beta-carotene was also essential. Also, increase in the polarity of the functional groups expressed, for instance, in Taft sigma* substituent constants had its impact. The HyperChem 7 followed by Gaussian 03 computations revealed that the inclusion SWCNT-carotenoid complexes were more stable than corresponding surface complexes. In the surface complexes carotenoids acted as donors in respect to SWCNT whereas in the inclusion complexes they were acceptors.


Asunto(s)
Carbono/química , Carotenoides/química , Nanotecnología , Rastreo Diferencial de Calorimetría , Espectrofotometría Ultravioleta , Espectrometría Raman , Propiedades de Superficie
17.
J Nanosci Nanotechnol ; 5(3): 479-83, 2005 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-15913259

RESUMEN

Closed-end single-walled carbon nanotubes were wetted in aqueous solutions of monosaccharides, forming weak surface complexes, as proven by the estimation of the content of monosaccharides in complexes isolated from aqueous solutions. The complexation was confirmed by micro-Raman spectroscopy. The Gaussian 03 (Molecular Mechanics UFF method) computations of total energy of the single-walled carbon nanotube-monosaccharides inclusion and surface complexes showed that inclusion complexes should be more stable than corresponding surface complexes. Computed total energies for particular complexes pointed to a lack of preferences for the formation of complexes with either alpha- or beta-tautomers and either pyranoses or furanoses. The forms preferred in the formation of the surface complexes usually differ from these favored in the formation of the inclusion complexes.


Asunto(s)
Modelos Químicos , Modelos Moleculares , Monosacáridos/química , Nanotubos de Carbono/química , Nanotubos de Carbono/ultraestructura , Agua/química , Sitios de Unión , Simulación por Computador , Cristalización/métodos , Sustancias Macromoleculares/análisis , Sustancias Macromoleculares/química , Conformación Molecular , Soluciones , Propiedades de Superficie
18.
J Plant Physiol ; 162(3): 355-61, 2005 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-15832688

RESUMEN

An effective procedure for obtaining healthy shoots from nodal segments of Scrophularia yoshimurae is described. Nodal segments cultured on Murashige and Skoog's (MS) basal medium supplemented with 1.0 mg L(-1) benzyladenine (BA) and 0.2 mg L(-1) alpha-naphthaleneacetic acid (NAA) induced multiple shoots in conical flasks that differed in the way they were closed and sealed. Hermitically sealed culture vessels resulted in high hyperhydricity/vitrification. High concentrations of ethylene and CO2 were found to accumulate in these vessels. The hyperhydricity of the shoot cultures could be decreased by progressively ventilating the vessels. Exchange of gases was achieved by removing the Parafilm sealing without affecting sterility. This reduced the hyperhydricity rate and gave a good recovery of vitrified shoots, but resulted in decreased proliferation and a dehydration of proliferating nodal segments and the culture medium. The best number of normal shoots was observed when the parafilm was removed for gaseous exchange after four weeks of culture incubation. The results show that hyperhydricity in shoot cultures of S. yoshimurae could be prevented by sufficient gas exchange during culture.


Asunto(s)
Brotes de la Planta/fisiología , Scrophularia/fisiología , Aerobiosis , Dióxido de Carbono/análisis , Técnicas de Cultivo de Célula , Medios de Cultivo , Flores/fisiología , Ácidos Naftalenoacéticos/farmacología , Brotes de la Planta/citología , Scrophularia/citología
19.
Beilstein J Nanotechnol ; 6: 1652-60, 2015.
Artículo en Inglés | MEDLINE | ID: mdl-26425415

RESUMEN

The main goal of this work is to study the structural and magnetic properties of iron nanowires and iron nanoparticles, which have been fabricated in almost the same processes. The only difference in the synthesis is an application of an external magnetic field in order to form the iron nanowires. Both nanomaterials have been examined by means of transmission electron microscopy, energy dispersive X-ray spectrometry, X-ray diffractometry and Mössbauer spectrometry to determine their structures. Structural investigations confirm that obtained iron nanowires as well as nanoparticles reveal core-shell structures and they are composed of crystalline iron cores that are covered by amorphous or highly defected phases of iron and iron oxides. Magnetic properties have been measured using a vibrating sample magnetometer. The obtained values of coercivity, remanent magnetization, saturation magnetization as well as Curie temperature differ for both studied nanostructures. Higher values of magnetizations are observed for iron nanowires. At the same time, coercivity and Curie temperature are higher for iron nanoparticles.

20.
J Nanosci Nanotechnol ; 3(1-2): 193-8, 2003.
Artículo en Inglés | MEDLINE | ID: mdl-12908250

RESUMEN

This paper reports a computational study of oxygen additions to narrow nanotubes, a problem frequently studied with fullerenes. In fact, fullerene oxides were the first observed fullerene derivatives, and they have naturally attracted the attention of both experiment and theory. C60O had represented a long-standing case of experiment-theory disagreement, and there has been a similar problem with C60O2. The disagreement has been explained by kinetic rather than thermodynamic control. In this paper a similar computational approach is applied to narrow nanotubes. Recently, very narrow nanotubes have been observed with a diameter of 5 A and even with a diameter of 4 A. It has been supposed that the narrow nanotubes are closed by fragments of small fullerenes like C36 or C20. In this report we perform calculations for oxygen additions to such model nanotubes capped by fragments of D2d C36, D4d C32, and Ih C20 fullerenic cages (though the computational models have to be rather short). The three models have the following carbon contents: C84, C80, and C80. Both thermodynamic enthalpy changes and kinetic activation barriers for oxygen addition to six selected bonds are computed and analyzed. The lowest isomer (thermodynamically the most stable) is never of the 6/6 type, that is, the enthalpically favored structures are produced by oxygen additions to the nanotube tips. Interestingly enough, the lowest energy isomer has, for the D2d C36 and D4d C32 cases, the lowest kinetic activation barrier as well.


Asunto(s)
Cristalografía/métodos , Modelos Moleculares , Nanotubos de Carbono/química , Nanotubos de Carbono/clasificación , Oxígeno/química , Simulación por Computador , Transferencia de Energía , Entropía , Conformación Molecular , Estructura Molecular , Nanotecnología/métodos , Oxidación-Reducción , Teoría Cuántica , Estereoisomerismo , Termodinámica
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