Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 47
Filtrar
Mais filtros








Base de dados
Intervalo de ano de publicação
1.
Materials (Basel) ; 15(21)2022 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-36363045

RESUMO

The superior hydrogen storage properties makes the KSiH3 system a potential hydrogen storage material for practical applications. A theoretical capacity of 4.3 wt% bring this material to the front line of all the available hydrogen storage materials; however, the activation barrier of the reaction restricts the system to absorb and desorb hydrogen reversibly at elevated temperatures even if the thermodynamics suggest its room temperature operation. Several catalysts have already been tested to enhance its kinetic properties. In this work, the efforts were made to reduce the activation energy by using Zr-based catalysts to the KSi/KSiH3 system. The value of activation energy was found to be lowest (i.e., 87 kJ mol-1) for the ZrH2-added KSiH3 system. The mechanism of this improvement was investigated by using X-ray photoelectron spectroscopy (XPS).

2.
Molecules ; 27(13)2022 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-35807339

RESUMO

The hunt for a cleaner energy carrier leads us to consider a source that produces no toxic byproducts. One of the targeted alternatives in this approach is hydrogen energy, which, unfortunately, suffers from a lack of efficient storage media. Solid-state hydrogen absorption systems, such as lithium amide (LiNH2) systems, may store up to 6.5 weight percent hydrogen. However, the temperature of hydrogenation and dehydrogenation is too high for practical use. Various molar ratios of LiNH2 with sodium hydride (NaH) and potassium hydride (KH) have been explored in this paper. The temperature of hydrogenation for LiNH2 combined with KH and NaH was found to be substantially lower than the temperature of individual LiNH2. This lower temperature operation of both LiNH2-NaH and LiNH2-KH systems was investigated in depth, and the eutectic melting phenomenon was observed. Systematic thermal studies of this amide-hydride system in different compositions were carried out, which enabled the plotting of a pseudo-binary phase diagram. The occurrence of eutectic interaction increased atomic mobility, which resulted in the kinetic modification followed by an increase in the reactivity of two materials. For these eutectic compositions, i.e., 0.15LiNH2-0.85NaH and 0.25LiNH2-0.75KH, the lowest melting temperature was found to be 307 °C and 235 °C, respectively. Morphological studies were used to investigate and present the detailed mechanism linked with this phenomenon.

3.
Pediatr Investig ; 5(4): 293-298, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34938972

RESUMO

The clinical outcomes of adolescents with avoidant/restrictive food intake disorder (ARFID) remain unclear. Furthermore, no report has compared the characteristics of ARFID and restricting-type anorexia nervosa (R-AN) in elementary-school students on total parenteral nutrition (TPN). This study retrospectively reviewed inpatients diagnosed with ARFID or R-AN between 2005 and 2019. Patients with ARFID (two boys and seven girls) and R-AN (13 girls) were hospitalized because of rapid physical deterioration, and nutrition therapy was continued without withdrawal. The ARFID group exhibited significantly lower body weights at admission than the R-AN group and gained an average of 6.5 kg during hospitalization; furthermore, the monthly weight gain during hospitalization was significantly higher, and no relapse was observed. Early physical improvement in ARFID resulted in good recovery. In conclusion, TPN can be easily introduced to patients with ARFID, in whom aversive eating is a concern, and is a suitable treatment for ARFID.

4.
ACS Omega ; 6(36): 23442-23446, 2021 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-34549142

RESUMO

Ammonia is an important fertilizer feedstock and an expected next-generation hydrogen carrier. Thus, it is necessary to ensure effective production of ammonia from the waste biomass. In this regard, chicken manure was treated in an autoclave under hydrothermal reaction conditions, and the ammonia release rate was determined in the temperature range of 250-400 °C for holding times ranging from 2 to 120 min. A reaction network for ammonia production was proposed, and the reaction rate constants were determined. A nitrogen yield as high as 0.8 was obtained, corresponding to a hydrogen potential of 88.1 billion m3/year from chicken manure. Consequently, chicken manure was identified as a potentially favorable feedstock for ammonium production.

5.
ACS Omega ; 6(36): 23564-23569, 2021 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-34549153

RESUMO

Five types of niobium(V) oxides (Nb2O5) were synthesized by hydrothermal and heat treatment processes, and their structural properties and catalytic activities for the hydrogen absorption/desorption reactions of magnesium were characterized. The synthesized Nb oxides were dispersed on magnesium hydride (MgH2), a typical hydrogen storage material, using the ball-milling method. All the synthesized Nb oxides improved the reaction kinetics of the hydrogen desorption/absorption reactions. The catalytic activities for the hydrogen desorption were comparable, while the hydrogen absorption rates were significantly different for each synthesized Nb oxide. This difference can be explained by the structural stability of Nb2O5, which is related to the formation of a catalytically active state by the reduction of Nb2O5 during the ball-milling process. Notably, the highest catalytic effect was observed for Nb2O5 with a highly crystalline pyrochlore structure and a low specific surface area, suggesting that pyrochlore Nb2O5 is a metastable phase. However, only the amorphous Nb oxide was out of order, even though there is a report on the high catalytic activity of amorphous Nb oxide. This is attributed to the initial condensed state of amorphous Nb oxide, because particle size affects the dispersion state on the MgH2 surface, which is also important for obtaining high catalytic activity. Thus, it is concluded that Nb2O5 with lower stability of the crystal structure and smaller particle size shows better catalysis for both hydrogen desorption and absorption reactions.

6.
Chem Commun (Camb) ; 57(49): 6003-6006, 2021 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-34075951

RESUMO

NaBH4 does not absorb NH3 below 100 kPa but transforms into a liquid state after NH3 absorption. On the other hand, LiBH4 absorbs NH3 at pressures lower than 100 kPa. Interestingly, mixed borohydrides absorbed NH3 at low pressures and were liquefied above 100 kPa due to a synergetic phenomenon. The kinematic viscosity of the liquefied state was in situ analyzed during NH3 absorption.

7.
RSC Adv ; 11(34): 21017-21022, 2021 Jun 09.
Artigo em Inglês | MEDLINE | ID: mdl-35479336

RESUMO

In this study, the investigation of materials with corrosion resistance was carried out to prevent side reactions caused by sodium oxide (Na2O) in the Na-redox thermochemical water splitting cycle, and essential operational conditions for sodium (Na) generation from Na2O were also investigated. Thermal desorption spectroscopy and X-ray diffraction techniques at altered conditions were mainly used for the experimental investigation. Numerous types of materials were tested to find materials with high resistance towards corrosion and to understand essential thermal decomposition processes of Na2O. In addition, under different temperatures and pressure conditions, the thermodynamic calculation of Gibbs free energy was performed to obtain experimental results. As a result, a Ti alloy showed significant resistance towards the corrosive reaction by Na2O. The obtained experimental and simulated results support the direct decomposition of Na2O to form Na and O2 below 600 °C under low partial pressure conditions. The optimized conditions for Na generation with the Ti alloy sample can be used for low temperature water splitting.

8.
ACS Omega ; 5(34): 21906-21912, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-32905312

RESUMO

Magnesium is a promising hydrogen storage material but requires an efficient catalyst to enhance the sluggish kinetics of its hydrogen desorption/absorption reactions. Niobium catalysts have been shown to accomplish this, but the effective factors for catalysis on hydrogen desorption/absorption of Mg are not well understood. In order to investigate these aspects, various types of Nb oxides were synthesized and mixed with Mg, and their catalytic properties were investigated. The spray pyrolysis synthesis of Nb oxides at different temperatures produced homogeneous spherical particles with different degrees of crystallinity, while Nb oxide particles synthesized by simple calcination of ammonium niobium oxalate were nonuniform. These Nb oxides show significant catalytic activities for the hydrogen desorption/absorption of Mg, with amorphous oxides being more effective catalyst precursors than crystalline precursors. Metastable, amorphous Nb oxide is more easily converted to the reduced state, which is the catalytically active state for the reactions. In addition, Nb in the deactivated sample is in the oxidized state compared with the initially activated sample, and the catalytically active (reduced) state is recovered by reactions with hydrogen. Based on these findings, it is concluded that the chemical state of Nb is an important factor in catalyzing the desorption/absorption of hydrogen by Mg, and the catalytically active state can be preserved without further treatments.

9.
Molecules ; 25(16)2020 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-32824210

RESUMO

Bismuth chalcogenide (Bi2X3; X = sulfur (S), selenium (Se), and tellurium (Te)) materials are considered as promising materials for diverse applications due to their unique properties. Their narrow bandgap, good thermal conductivity, and environmental friendliness make them suitable candidates for thermoelectric applications, photodetector, sensors along with a wide array of energy storage applications. More specifically, their unique layered structure allows them to intercalate Li+ ions and further provide conducting channels for transport. This property makes these suitable anodes for Li-ion batteries. However, low conductivity and high-volume expansion cause the poor electrochemical cyclability, thus creating a bottleneck to the implementation of these for practical use. Tremendous endeavors have been devoted towards the enhancement of cyclability of these materials, including nanostructuring and the incorporation of a carbon framework matrix to immobilize the nanostructures to prevent agglomeration. Apart from all these techniques to improve the anode properties of Bi2X3 materials, a step towards all-solid-state lithium-ion batteries using Bi2X3-based anodes has also been proven as a key approach for next-generation batteries. This review article highlights the main issues and recent advances associated with Bi2X3 anodes using both solid and liquid electrolytes.


Assuntos
Bismuto/química , Calcogênios/química , Fontes de Energia Elétrica , Lítio/química , Eletrodos
10.
Chem Commun (Camb) ; 56(53): 7237-7240, 2020 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-32495781

RESUMO

Surface modification effects of graphite and organic solvents on Ti were investigated by thermogravimetry (TG), Raman spectroscopy, and transmission electron microscopy (TEM) observations to improve its hydrogen absorption properties. As a result, Ti ball-milled with graphite showed high reactivity and selectivity for hydrogen with high durability.

11.
Case Rep Oncol ; 13(3): 1513-1519, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33564292

RESUMO

A huge abdominal cystic lesion with ascites was detected in a male neonate at 31 weeks of gestation. Increasing ascites and the appearance of subcutaneous edema were detected, which caused fetal hydrops. The patient was delivered by emergency cesarean section at 33 weeks of gestation. The birth weight was 2,407 g, and the Apgar score was 8/9 points (1-/5-min values). Breathing at birth was stable, but the patient presented with remarkable abdominal distention due to the ascites. Later, the patient presented with tachypnea, and breathing gradually worsened, so an emergency operation was performed. There were no intraoperative findings within the small intestine, but there was a large amount of ascites and a cystic mass arising from the liver. The patient's breathing and circulation dynamics could only be stabilized by ascites removal, so only a tumor biopsy was performed. The pathological findings led to the diagnosis of an inflammatory myofibroblastic tumor, and steroids were administered early after surgery for the purpose of an anti-inflammatory effect and tumor shrinkage. The abdominal distention was alleviated, and blood examinations showed a reduced inflammatory response. There was no apparent shrinkage of the tumor, however; thus, radical surgical treatment was performed on day 24. The postoperative course was uneventful, so the patient was discharged on day 36. Seven years after the operation there has been no recurrence or distant metastasis.

12.
J Blood Med ; 10: 301-306, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31695540

RESUMO

PURPOSE: Hemophagocytic lymphohistiocytosis (HLH) is a potentially lethal hyperinflammatory disorder. For further understanding of the pathogenesis of HLH, we examined serum levels of high mobility group box protein 1 (HMGB1) in children with HLH. PATIENTS AND METHODS: Serum HMGB1 levels were measured in 28 patients with HLH and 6 normal controls using a quantitative enzyme-linked immunosorbent assay. The patients were 21 boys and 7 girls, aged from 10 days to 21 years, with a median age of 8.5 years. The underlying conditions of HLH were infection-associated HLH in 18 patients, malignancy-associated HLH in 7 patients, and genetic HLH in 3 patients. The relations between serum HMGB1 levels and clinical symptoms and laboratory parameters were analyzed. RESULTS: Serum HMGB1 levels were significantly higher in patients with HLH than in normal controls (median, 6.5 ng/mL, interquartile range, 4.25-13.1). The serial serum HMGB1 levels in one patient fell to reflect the disease activity. Serum HMGB1 levels were significantly higher in patients with disseminated intravascular coagulation (DIC) than in patients without DIC (p<0.001) and were also significantly higher in patients with central nervous system (CNS) complications than in patients without CNS complications (p<0.01). Serum HMGB1 levels were positively correlated with aspartate aminotransferase (rs =0.48, p<0.01, Spearman's rank correlation coefficient) and negatively correlated with fibrinogen (rs = -0.475, p=0.011) and hemoglobin (rs = -0.465, p=0.013). CONCLUSION: Serum HMGB1 levels reflect clinical features of childhood HLH. HMGB1 is a potential mediator involved in the pathogenesis and determining the clinical findings of HLH.

14.
Int Cancer Conf J ; 8(3): 95-100, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31218182

RESUMO

The dismal prognosis of patients with disseminated Ewing sarcoma necessitates the development of novel treatment strategies. Pazopanib is an oral multi-targeted tyrosine kinase inhibitor that is active against advanced soft tissue sarcoma. However, the clinical activity and feasibility of pazopanib for treating Ewing sarcoma remain poorly understood. Moreover, clinical information on the use of tandem high-dose chemotherapy for Ewing sarcoma is limited. A 14-year-old boy with Ewing sarcoma was transferred to our hospital for treatment. Magnetic resonance imaging, computed tomography scans, and bone scintigraphy revealed multiple lesions in the pubis, ilium, ischium, femur, rib, cranial bone, thoracic vertebrae, sacrum, obturator muscle, adductor magnus muscle, testicular cord, and lungs. Bone scintigraphy after intensive chemotherapies confirmed that multiple abnormal accumulations were still present in the cranial bone and pubis. Subsequently, the patient received tandem high-dose chemotherapy including topotecan, and radiotherapy. Abnormal accumulations have disappeared in bone scintigraphy. Subsequently, pazopanib maintenance therapy was initiated. Despite the presence of innumerable lesions at diagnosis, the patient has been in near-complete remission for the past 1 year with pazopanib administration. This confirms that adding pazopanib maintenance therapy after tandem high-dose chemotherapy is a therapeutic option for cases with disseminated Ewing sarcoma.

15.
Molecules ; 24(7)2019 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-30959780

RESUMO

Hydrogenation of a lithium-potassium (double-cation) amide (LiK(NH2)2), which is generated as a product by ammonolysis of litium hydride and potassium hydride (LiH-KH) composite, is investigated in details. As a result, lithium amide (LiNH2) and KH are generated after hydrogenation at 160 °C as an intermediate. It is noteworthy that the mixture of LiH and KNH2 has a much lower melting point than that of the individual melting points of LiNH2 and KH, which is recognized as a eutectic phenomenon. The hydrogenation temperature of LiNH2 in the mixture is found to be significantly lower than that of LiNH2 itself. This improvement of reactivity must be due to kinetic modification, induced by the enhanced atomic mobility due to the eutectic interaction.


Assuntos
Amidas/química , Hidrogênio/química , Lítio/química , Potássio/química , Amônia/química , Hidrogenação , Cinética
16.
Chem Commun (Camb) ; 55(15): 2150-2153, 2019 Feb 14.
Artigo em Inglês | MEDLINE | ID: mdl-30608079

RESUMO

The ammonia absorption process of sodium borohydride for ammonia storage has been studied by using the operando NMR and FT-IR measurements under various ammonia pressures. As a result, the characteristic variation in the chemical states of both materials due to the liquefaction has been clarified.

17.
RSC Adv ; 9(23): 13077-13081, 2019 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-35520813

RESUMO

Herein, we employed Bi and Sb as the negative electrode in all solid-state lithium-ion batteries (LIBs) using LiBH4 as the solid-state electrolyte. The composite anode materials with acetylene black (AB) and LiBH4, prepared by high energy ball-milling, have shown extremely high stability with a high coulombic efficiency of 90-99% over a number of cycles. The gravimetric capacity decayed by only 18 and 5% as compared to the initial volumetric capacity of 4681.7 and 4393.4 mA h cm-3 for Bi and Sb anodes respectively.

18.
RSC Adv ; 9(51): 29549-29555, 2019 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-35531550

RESUMO

Herein, we introduce the detailed electrochemical reaction mechanism of Bi2S3 (bulk as well as nanostructure) as a highly efficient anode material with Li-ions in an all-solid-state Li-ion battery (LIB). Flower-like Bi2S3 nanostructures were synthesized by a hydrothermal method and were used as an anode material in a LIB with LiBH4 as a solid electrolyte. The X-ray diffraction (XRD) pattern verified the formation of Bi2S3 nanostructures, which belongs to the orthorhombic crystal system (JCPDS no. 00-006-0333) with the Pbnm space group. Morphological studies confirmed the flower-like structure of the obtained product assembled from nanorods with the length and diameter in the range of 150-400 nm and 10-150 nm respectively. The electrochemical galvanostatic charge-discharge profile of these nanostructures demonstrates exciting results with a high discharge and charge capacity of 685 mA h g-1 & 494 mA h g-1 respectively at 125 °C. The discharge and charge capacities were observed as 375 mA h g-1 and 352 mA h g-1 after 50 cycles (with 94% coulombic efficiency), which are much better than the cells having bulk Bi2S3 as the anode material.

19.
Case Rep Oncol ; 11(1): 63-67, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29515412

RESUMO

Acute lymphoblastic leukemia (ALL) presenting as Fanconi syndrome (FS) is extremely rare. Here, we report a case of ALL presenting as bilateral nephromegaly following FS. A 2-year-old girl was unexpectedly diagnosed with bilateral nephromegaly. After 2 weeks, she developed general fatigue, thirst, and polyuria. Laboratory examinations revealed renal tubular acidosis, hypokalemia, hypophosphatemia, and aminoaciduria, and FS was diagnosed. Replacement of bicarbonate and potassium did not improve her condition. Two weeks after the onset of FS, leukemic cells appeared on a peripheral blood smear, and the patient was diagnosed with precursor B-cell ALL presenting as nephromegaly and FS. Chemotherapy brought about a prompt resolution of acidosis and electrolyte abnormalities, without renal dysfunction. The patient remains well 4 years after the onset of the disease. Although extremely rare, FS should be recognized as one of the emerging renal complications of ALL.

20.
RSC Adv ; 8(41): 23468-23474, 2018 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-35540131

RESUMO

Several studies have demonstrated that MgH2 is a promising conversion-type anode toward Li. A major obstacle is the reversible capacity during cycling. Electrochemical co-existence of a mixed metal hydride-oxide conversion type anode is demonstrated for lithium ion batteries using a solid-state electrolyte. 75MgH2·25CoO anodes are obtained from optimized mixing conditions avoiding reactions occurring during high-energy ball-milling. Electrochemical tests are carried out to investigate the cycling capability and reversibility of the on-going conversion reactions. The cycling led to formation of a single-plateau nanocomposite electrode with higher reversibility yield, lowered discharge-charge hysteresis and mitigated kinetic effect at high C-rate compared to MgH2 anodes. It is believed that reduced diffusion pathways and less polarized electrodes are the origin of the improved properties. The designed composite-electrode shows good preservation and suitability with LiBH4 solid electrolyte as revealed from electron microscopy analyses and X-ray photoelectron spectroscopy.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA