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1.
Polymers (Basel) ; 15(18)2023 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-37765597

RESUMO

Three-dimensional (3D) printing is a versatile manufacturing method widely used in various industries due to its design flexibility, rapid production, and mechanical strength. Polyurethane (PU) is a biopolymer frequently employed in 3D printing applications, but its susceptibility to UV degradation limits its durability. To address this issue, various additives, including graphene, have been explored to enhance PU properties. Graphene, a two-dimensional carbon material, possesses remarkable mechanical and electrical properties, but challenges arise in its dispersion within the polymer matrix. Surface modification techniques, like polydopamine (PDA) coating, have been introduced to improve graphene's compatibility with polymers. This study presents a method of 3D printing PU scaffolds coated with PDA and graphene for enhanced UV stability. The scaffolds were characterized through X-ray diffraction, Fourier-transform infrared spectroscopy, mechanical testing, scanning electron microscopy, and UV durability tests. Results showed successful PDA coating, graphene deposition, and improved mechanical properties. The PDA-graphene-modified scaffolds exhibited greater UV resistance over time, attributed to synergistic effects between PDA and graphene. These findings highlight the potential of combining PDA and graphene to enhance the stability and mechanical performance of 3D-printed PU scaffolds.

2.
Technol Cancer Res Treat ; 22: 15330338231201508, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37735896

RESUMO

PURPOSE: This study aimed to evaluate the efficacy of computed tomography (CT) guided percutaneous cryoablation (CA) for the management of lung metastases in patients with metastatic colorectal cancer (mCRC). METHODS: Retrospective analysis was performed on 38 mCRC patients with lung metastases, who underwent CT-guided percutaneous CA at our center from May 1, 2020 to November 1, 2021. The technical success rate, 1-year local control (LC) rate, recurrence-free survival (RFS) and treatment-related complications were analyzed. RESULTS: The CA procedure was successfully performed in all patients, with a technical success rate of 100%. The 1-year LC rate was 94.7% (36/38), while 16 patients experienced new distant lung metastases during the follow-up period. The median RFS was 20 months (95% CI: 13.0-27.0). The median RFS of patients with and without extrapulmonary metastasis was 15 and 23 months, respectively. Complications were reported in 18 (47.4%) patients following the CA procedure. Pneumothorax was discovered in 15 (39.5%) patients, and five of these patients (13.2%) required chest tube intubation. Two patients (5.3%) presented with hemoptysis during the CA procedure. One patient developed subcutaneous emphysema as detected in the post-procedure follow-up imaging. All patients tolerated the peri-procedural pain well under local anesthesia, and the mean visual analog scale (VAS) score was 2.8. CONCLUSION: Lung CA is a safe and well-tolerated treatment with a satisfactory local control rate for patients with lung metastases derived from mCRC.


Assuntos
Criocirurgia , Neoplasias Pulmonares , Neoplasias Retais , Humanos , Resultado do Tratamento , Estudos Retrospectivos , Criocirurgia/efeitos adversos , Criocirurgia/métodos , Neoplasias Pulmonares/diagnóstico por imagem , Neoplasias Pulmonares/cirurgia , Tomografia Computadorizada por Raios X/métodos
3.
Polymers (Basel) ; 15(9)2023 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-37177357

RESUMO

Lithium cobalt oxide (LiCoO2, LCO) has been widely used in electronic markets due to its high energy density and wide voltage range applications. Recently, high-voltage (HV, >4.5 V) operation has been required to obey the requirements of high energy density and cycle life in several applications such as electric vehicles and energy storage. However, the HV operation causes structure instability due to the over de-lithiation of LCO, as well as decomposing common carbonate solvents, thereby incurring the decay of battery performance. Moreover, a distortion of the CoO6 octahedra of LCO during de-lithiation induces a rehybridization of the Co 3d and O 2p orbitals. According to above reasons, decreasing the Co-O covalent bond promptly triggers high risks that significantly limit further use of LCO. In this research, an organic surface reinforcement by using bismaleimide-uracil (BU) that electrochemically forms a cathode electrolyte interphase (CEI) on LCO was explored. The results of electrochemical impedance spectroscopy and battery performance, such as the c-rate and cyclability tests, demonstrated that the modified CEI formed from BU significantly prevents the distortion of CoO6 octahedra. X-ray photoelectronic spectroscopy and in situ XAS indicated less LiF formation and higher bond energy of Co-O improved. Finally, the differential scanning calorimetry showed the onset temperature of decomposition of LCO was extended from 245 to 270 °C at 100% state of charge, which is about a 25 °C extension. The exothermic heat of LCO decreased by approximately 30% for high-safety use. This research confirms that the BU is eligible for high voltage (>4.5 V) LCO and presents outstanding electrochemical properties and safety performances.

4.
Bioelectrochemistry ; 152: 108430, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37043880

RESUMO

In this work, we demonstrated a novel cancer antigen 125 (CA125) biomarker detection based on electrochemical immunosensor. The biomarker on conductive composite materials of carbon ink/carbon dot/zine oxide (C-ink/CD/ZnO) was employed as an electrode platform by using ITO substrate to enhance the interaction of antibodies (Ab) with supporting catalytic performance of ZnO as a labeling signal molecule. They were a scientist attention for biosensor with chemical stability, strong biocompatibility, high conductive signal, and accuracy. Moreover, the nanocomposite of silver@polypyrrole (Ag@PPy) was used as a potential redox mediator. The labeled construction with Ag@PPy was more accuracy than that of a free-labeled. The created immunosensor was a wide linear range as 1 ag·mL-1 - 100 ng·mL-1 and a low limitation of detection as 0.1 fg·mL-1 under the optimal condition. This suggested that the immunosensor is considered to be an accurate and efficient diagnostic tool for CA125 and other biomarkers detection in actual sample analysis for clinic.


Assuntos
Técnicas Biossensoriais , Nanopartículas Metálicas , Neoplasias Ovarianas , Óxido de Zinco , Feminino , Humanos , Carbono/química , Polímeros/química , Pirróis , Antígeno Ca-125/análise , Tinta , Técnicas Eletroquímicas , Imunoensaio , Limite de Detecção , Nanopartículas Metálicas/química
5.
Sensors (Basel) ; 23(3)2023 Jan 18.
Artigo em Inglês | MEDLINE | ID: mdl-36772172

RESUMO

Developing label-free immunosensors to detect ovarian cancer (OC) by cancer antigen (CA125) is essential to improving diagnosis and protecting women from life-threatening diseases. Four types of carbon nanomaterials, such as multi-wall carbon nanotubes (MWCNTs), vapor-grown carbon fiber (VGCFs), graphite KS4, and carbon black super P (SP), have been treated with acids to prepare a carbon nanomaterial/gold (Au) nanocomposite. The AuNPs@carbon nanocomposite was electrochemically deposited on a glassy carbon electrode (GCE) to serve as a substrate to fabricate a label-free immunosensor for the detection of CA125. Among the four AuNPs@carbon composite, the AuNPs@MWCNTs-based sensor exhibited a high sensitivity of 0.001 µg/mL for the biomarker CA125 through the square wave voltammetry (SWV) technique. The high conductivity and surface area of MWCNTs supported the immobilization of AuNPs. Moreover, the carboxylic (COO-) functional groups in MWCNT improved to a higher quantity after the acid treatment, which served as an excellent support for the fabrication of electrochemical biosensors. The present method aims to explore an environmentally friendly synthesis of a layer-by-layer (LBL) assembly of AuNPs@carbon nanomaterials electrochemical immunoassay to CA125 in a clinical diagnosis at a low cost and proved feasible for point-of-care diagnosis.


Assuntos
Técnicas Biossensoriais , Nanopartículas Metálicas , Nanotubos de Carbono , Neoplasias Ovarianas , Humanos , Feminino , Técnicas Biossensoriais/métodos , Ouro , Imunoensaio/métodos , Neoplasias Ovarianas/diagnóstico , Eletrodos , Técnicas Eletroquímicas/métodos , Limite de Detecção
6.
Membranes (Basel) ; 12(4)2022 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-35448399

RESUMO

In recent years, the emergence of disparate micro-contaminants in aquatic environments such as water/wastewater sources has eventuated in serious concerns about humans' health all over the world. Membrane bioreactor (MBR) is considered a noteworthy membrane-based technology, and has been recently of great interest for the removal micro-contaminants. The prominent objective of this review paper is to provide a state-of-the-art review on the potential utilization of MBRs in the field of wastewater treatment and micro-contaminant removal from aquatic/non-aquatic environments. Moreover, the operational advantages of MBRs compared to other traditional technologies in removing disparate sorts of micro-contaminants are discussed to study the ways to increase the sustainability of a clean water supplement. Additionally, common types of micro-contaminants in water/wastewater sources are introduced and their potential detriments on humans' well-being are presented to inform expert readers about the necessity of micro-contaminant removal. Eventually, operational challenges towards the industrial application of MBRs are presented and the authors discuss feasible future perspectives and suitable solutions to overcome these challenges.

7.
Acta Chim Slov ; 68(3): 541-547, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34897549

RESUMO

A series of five new fluoro-substituted aroylhydrazones were prepared and structurally characterized by elemental analysis, IR, UV-Vis and 1H NMR spectroscopy, as well as single crystal X-ray diffraction. The compounds were evaluated for their antibacterial (Bacillus subtilis, Staphylococcus aureus, Escherichia coli, and Pseudomonas fluorescence) and antifungal (Candida albicans and Aspergillus niger) activities by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide) method. The biological assay indicated that the presence of the electron-withdrawing groups in the aroylhydrazones improved their antimicrobial activities.


Assuntos
Antibacterianos/farmacologia , Antifúngicos/farmacologia , Hidrazonas/farmacologia , Antibacterianos/síntese química , Antifúngicos/síntese química , Aspergillus niger/efeitos dos fármacos , Bactérias/efeitos dos fármacos , Candida albicans/efeitos dos fármacos , Hidrazonas/síntese química , Testes de Sensibilidade Microbiana , Estrutura Molecular , Relação Estrutura-Atividade
8.
Nanomaterials (Basel) ; 11(11)2021 Nov 19.
Artigo em Inglês | MEDLINE | ID: mdl-34835884

RESUMO

In this study we prepared potassium-ion batteries (KIBs) displaying high output voltage and, in turn, a high energy density, as replacements for lithium-ion batteries (LIBs). Organic electrode materials featuring void spaces and flexible structures can facilitate the mobility of K+ to enhance the performance of KIBs. We synthesized potassium maleamate (K-MA) from maleamic acid (MA) and applied as an anode material for KIBs and LIBs, with 1 M potassium bis(fluorosulfonyl)imide (KFSI) and 1 M lithium bis(fluorosulfonyl)imide (LiFSI) in a mixture of ethylene carbonate and ethyl methyl carbonate (1:2, v/v) as respective electrolytes. The K-MA_KFSI anode underwent charging/discharging with carbonyl groups at low voltage, due to the K···O bond interaction weaker than Li···O. The K-MA_KFSI and K-MA_LiFSI anode materials delivered a capacity of 172 and 485 mA h g-1 after 200 cycles at 0.1C rate, respectively. K-MA was capable of accepting one K+ in KIB, whereas it could accept two Li+ in a LIB. The superior recoveries performance of K-MA_LiFSI, K-MA_KFSI, and Super P_KFSI at rate of 0.1C were 320, 201, and 105 mA h g-1, respectively. This implies the larger size of K+ can reversibly cycling at high rate.

9.
Anal Biochem ; 634: 114393, 2021 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-34597616

RESUMO

The electrochemical performance of dual layer immunosensor has been studied by employing reduced Graphene oxide (rGO) and its nanocomposites with Carbon Nanofibers (CNFs) and Carbon Nanotubes (CNTs) as supporting matrix for the detection of CA125. The immunosensor determination was based on the formation of antibody - antigen immunocomplex, a decrement in the current response was observed in accordance with the concentration of antigen. Better performance exhibited by rGO/CNF in terms of linearity (99%) and sensitivity 0.65 µA (µg mL-1)-1 can be attributed to its conductivity and surface area. The nanocomposite are employed in the detection of CA125 with linear working range of 10-32 × 10-4 µg mL-1, the limit of detection is found to be 0.28 pg mL-1 rGO nanocomposite with CNT (rGO/CNT) is studied as transducer material. rGO/CNT exhibited better linearity when compared to rGO due to its good conductivity. Thus, graphene nanocomposite transducer materials have vital application in detection of oncomarkers.


Assuntos
Técnicas Biossensoriais/métodos , Antígeno Ca-125/análise , Grafite/química , Nanocompostos/química , Nanotubos de Carbono/química , Carbono/química , Condutividade Elétrica , Técnicas Eletroquímicas , Ouro/química , Humanos , Imunoensaio/métodos , Limite de Detecção , Nanopartículas Metálicas/química , Nanofibras/química , Espectroscopia Fotoeletrônica/métodos
10.
ACS Appl Mater Interfaces ; 13(37): 44266-44273, 2021 Sep 22.
Artigo em Inglês | MEDLINE | ID: mdl-34494812

RESUMO

An effective Ru/CNT electrocatalyst plays a crucial role in solid-state lithium-carbon dioxide batteries. In the present article, ruthenium metal decorated on a multi-walled carbon nanotubes (CNTs) is introduced as a cathode for the lithium-carbon dioxide batteries with Li1.5Al0.5Ge1.5(PO4)3 solid-state electrolyte. The Ru/CNT cathode exhibits a large surface area, maximum discharge capacity, excellent reversibility, and long cycle life with low overpotential. The electrocatalyst achieves improved electrocatalytic performance for the carbon dioxide reduction reaction and carbon dioxide evolution reaction, which are related to the available active sites. Using the Ru/CNT cathode, the solid-state lithium-carbon dioxide battery exhibits a maximum discharge capacity of 4541 mA h g-1 and 45 cycles of battery life with a small voltage gap of 1.24 V compared to the CNT cathode (maximum discharge capacity of 1828 mA h g-1, 25 cycles, and 1.64 V as voltage gap) at a current supply of 100 mA g-1 with a cutoff capacity of 500 mA h g-1. Solid-state lithium-carbon dioxide batteries have shown promising potential applications for future energy storage.

11.
ACS Appl Mater Interfaces ; 13(39): 46703-46716, 2021 Oct 06.
Artigo em Inglês | MEDLINE | ID: mdl-34549937

RESUMO

Highly delithiated LiCoO2 has high specific capacity (>200 mAh g-1); however, its degradation behavior causes it to have poor electrochemical performance and thermal instability. The degradation of highly delithiated LiCoO2 is mainly induced by oxygen vacancy migration and weakening of oxygen-related interactions, which result in pitting corrosion and fault formation on the surface. In this research, a coupling agent, namely, 3-aminopropyltriethoxysilane (APTES), was grafted onto the surface of LiCoO2 to form a cross-linking structure. Through the aza-Michael addition reaction, an oligomer formed from barbituric acid and bisphenol a diglycidyl ether diacrylate were reacted with the cross-linking APTES to form an artificial cathode electrolyte interphase (ACEI). The highly delithiated LiCoO2 containing the ACEI had considerably less degradation on the surface of the bulk material caused by oxygen release. The formation of the O1 phase was prevented in high delithiation and high-temperature operations. This research revealed that the ACEI reinforced the Co-O bond, which is crucial in preventing gas evolution and O1 phase formation. In addition, the ACEI prevents direct contact between the electrolyte and highly active surface of LiCoO2, thereby preventing the formation of a thick and high impedance traditional cathode electrolyte interphase. According to the present results, highly delithiated LiCoO2 containing the ACEI exhibited outstanding cycle retention and capacity at 55 °C as well as low heat capacity release in the fully delithiated state. The ACEI considerably protected and maintained the electrochemical performance of highly delithiated LiCoO2, which is suitable for high-energy-density applications, such as electric vehicles and power tools.

12.
ACS Appl Mater Interfaces ; 13(6): 7355-7369, 2021 Feb 17.
Artigo em Inglês | MEDLINE | ID: mdl-33534550

RESUMO

Ni-rich high-energy-density lithium ion batteries pose great risks to safety due to internal short circuits and overcharging; they also have poor performance because of cation mixing and disordering problems. For Ni-rich layered cathodes, these factors cause gas evolution, the formation of side products, and life cycle decay. In this study, a new cathode electrolyte interphase (CEI) for Ni2+ self-oxidation is developed. By using a branched oligomer electrode additive, the new CEI is formed and prevents the reduction of Ni3+ to Ni2+ on the surface of Ni-rich layered cathode; this maintains the layered structure and the cation mixing during cycling. In addition, this new CEI ensures the stability of Ni4+ that is formed at 100% state of charge in the crystal lattice at high temperature (660 K); this prevents the rock-salt formation and the over-reduction of Ni4+ to Ni2+. These findings are obtained using in situ X-ray absorption spectroscopy, operando X-ray diffraction, operando gas chromatography-mass spectroscopy, and X-ray photoelectron spectroscopy. Transmission electron microscopy reveals that the new CEI has an elliptical shape on the material surface, which is approximately 100 nm in length and 50 nm in width, and covers selected particle surfaces. After the new CEI was formed on the surface, the Ni2+ self-oxidation gradually affects from the surface to the bulk of the material. It found that the bond energy and bond length of the Ni-O are stabilized, which dramatically inhibit gas evolution. The new CEI is successfully applied in a Ni-rich layered compound, and the 18650- and the punch-type full cells are fabricated. The energy density of the designed cells is up to 300 Wh/kg. Internal short circuit and overcharging safety tests are passed when using the standard regulations of commercial evaluation. This new CEI technology is ready and planned for future applications in electric vehicle and energy storage.

13.
ACS Appl Mater Interfaces ; 13(5): 6156-6167, 2021 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-33507065

RESUMO

Li-CO2 batteries have recently attracted attention as promising candidates for next-generation energy storage devices due to their extremely high theoretical energy density. The real application of Li-CO2 cells involves addressing several drawbacks, including high charging potential, poor coulombic efficiency, and low rechargeability. Molybdenum disulfide supported on carbon nanotubes (MoS2/CNT) with various ratios functioned as a cathode catalyst for Li-CO2 batteries. The optimal MoS2/CNT composite achieved a maximum discharge capacity of 8551 mAh g-1 with a coulombic efficiency of 96.7%. This hybrid also obtained an initial charging plateau of 3.87 V at a current density of 100 mA g-1 with a cutoff capacity of 500 mAh g-1. It provided ideal electrochemical stability of 142 cycles at the current densities of 100 mA g-1, which was comparable with that of some precious metal catalysts. This optimized MoS2/CNT was also cycled at 200 and 400 mA g-1 for 112 and 55 times, respectively. Density functional theory calculations demonstrated that the sulfided Mo-edge (s-Mo-edge) on MoS2 materials showed appropriate adsorption strengths of Li, CO2, and Li2CO3. Moreover, joint results of Raman profiles and extended X-ray absorption fine structure spectra elucidated that the catalytic efficiencies of MoS2/CNT hybrids were proportional to the quantities of exposed s-Mo-edge active sites.

14.
ACS Appl Mater Interfaces ; 13(1): 480-490, 2021 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-33375777

RESUMO

Alkali metal-carbon dioxide (Li/Na-CO2) batteries have generated widespread interest in the past few years owing to the attractive strategy of utilizing CO2 while still delivering high specific energy densities. Among these systems, Na-CO2 batteries are more cost effective than Li-CO2 batteries because the former uses cheaper and abundant Na. Herein, a Ru/carbon nanotube (CNT) as a cathode material was used to compare the mechanisms, stabilities, overpotentials, and energy densities of Li-CO2 and Na-CO2 batteries. The potential of Na-CO2 batteries as a viable energy storage technology was demonstrated.

15.
ACS Appl Mater Interfaces ; 12(27): 30915-30924, 2020 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-32539328

RESUMO

The development of science and technology is accompanied by a complex composition of multiple pollutants. Conventional passive separation processes are not sufficient for current industrial applications. The advent of active or responsive separation methods has become highly essential for future applications. In this work, we demonstrate the preparation of a smart electrically responsive membrane, a poly(vinylidene difluoride) (PVDF)-graphene composite membrane. The high graphene content induces the self-assembly of PVDF with a high ß-phase content, which displays a unique self-piezoelectric property. Additionally, the membrane exhibits excellent electrical conductivity and unique capacitive properties, and the resultant nanochannels in the membrane can be reversibly adjusted by external voltage applications, resulting in the tailored gas selectivity of a single membrane. After the application of voltage to the membrane, the permeability and selectivity toward carbon dioxide increase simultaneously. Moreover, atomic-level positron annihilation spectroscopic studies reveal the piezoelectric effect on the free volume of the membrane, which helps us to formulate a gas permeation mechanism for the electrically responsive membrane. Overall, the novel active membrane separation process proposed in this work opens new avenues for the development of a new generation of responsive membranes.

16.
Polymers (Basel) ; 12(5)2020 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-32414019

RESUMO

Low-molecular-weight carbonyl-containing compounds are considered beneficial energy storage materials in alkali metal-ion/alkaline earth metal-ion secondary batteries owing to the ease of their synthesis, low cost, rapid kinetics, and high theoretical energy density. This study aims to prepare a novel carbonyl compound containing a maleamic acid (MA) backbone as a material with carbon black to a new MA anode electrode for a lithium-ion battery. MA was subjected to attenuated total reflection-Fourier-transform infrared spectroscopy, and its morphology was assessed through scanning electron microscopy, followed by differential scanning calorimetry to determine its thermal stability. Thereafter, the electrochemical properties of MA were investigated in coin cells (2032-type) containing Li metal as a reference electrode. The MA anode electrode delivered a high reversible capacity of about 685 mAh g-1 in the first cycle and a higher rate capability than that of the pristine carbon black electrode. Energy bandgap analysis, electrochemical impedance, and X-ray photoelectron spectroscopy revealed that MA significantly reduces cell impedance by reforming its chemical structure into new nitrogen-based highly ionic diffusion compounds. This combination of a new MA anode electrode with MA and carbon black can increase the performance of the lithium-ion battery, and MA majorly outweighs transitional carbon black.

17.
ACS Appl Mater Interfaces ; 12(15): 17353-17363, 2020 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-32202752

RESUMO

Li-CO2 batteries are of great interest among researchers due to their high energy density and utilization of the greenhouse gas CO2 to produce energy. However, several shortcomings have been encountered in the practical applications of Li-CO2 batteries, among which their poor cyclability and high charge overpotential necessary to decompose the highly insulating discharge product (Li2CO3) are the most important. Herein, the spinel zinc cobalt oxide porous nanorods with carbon nanotubes (ZnCo2O4@CNTs) composite is employed as a cathode material in Li-CO2 batteries to improve the latter's cycling performance. The ZnCo2O4@CNT cathode-based Li-CO2 battery exhibited a full discharge capacity of 4275 mAh g-1 and excellent cycling performance over 200 cycles with a charge overpotential below 4.3 V when operated at a current density of 100 mA g-1 and fixed capacity of 500 mAh g-1. The superior performance of the ZnCo2O4@CNT cathode composite was attributed to the synergistic effects of ZnCo2O4 and CNT. The highly porous ZnCo2O4 nanorod structures in the ZnCo2O4@CNT catalyst showed enhanced catalytic activity/stability, which effectively promoted CO2 diffusion during the discharging process and accelerated Li2CO3 decomposition at a low charge overpotential.

18.
Acta Chim Slov ; 67(4): 1155-1162, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33533473

RESUMO

A new copper(II) complex [Cu(L1)(NCS)(CH3OH)] (1) and a new zinc(II) complex [ZnCl2(HL2)]·CH3OH (2), derived from 4-bromo-N'-(pyridin-2-ylmethylene)benzohydrazide (HL1) and 4-methoxy-N'-(pyridin-2-ylmethylene)benzohydrazide (HL2), were prepared and characterized by elemental analysis, IR and UV-Vis spectroscopy and single crystal X-ray diffraction. The hydrazone HL1 coordinates to the Cu atom in enolate form, while the hydrazone HL2 coordinates to the Zn atom in carbonyl form. Single crystal structural analyses indicate that the hydrazones coordinate to the metal atoms through the pyridine N, imino N, and enolate/carbonyl O atoms. The Cu atom in complex 1 is in square pyramidal coordination, and the Zn atom in complex 2 is in trigonal-bipyramidal coordination. The inhibitory effects of the complexes on Jack bean urease were studied, which show that the copper complex has strong activity on urease.

19.
Bioresour Technol ; 296: 122334, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31698223

RESUMO

Spent coffee grounds (SCGs) are a promising material for sustainable preparation of biodiesel. This study proposed a new approach for biodiesel synthesis from wet SCGs using 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) as both a green solvent and catalyst. The optimal reaction conditions were determined as a methanol amount of 6.25 mL/g of wet SCGs, DBU amount of 14.46 mL/g of wet SCGs, temperature of 60.2 °C, and reaction time of 28.65 min through response surface methodology. Under these conditions, the maximum biodiesel yield was 97.18%. Notably, DBU polarity could be regulated reversibly, facilitating its reusability and a simple process for product separation. Under optimal conditions, DBU could be potentially reused for at least 10 cycles to yield high amounts of biodiesel. This study suggests that the switchable solvent-assisted direct transesterification of wet SCGs is a potential, efficient, cost-effective, and eco-friendly approach for biodiesel synthesis.


Assuntos
Biocombustíveis , Café , Catálise , Esterificação , Metanol , Solventes
20.
ACS Appl Mater Interfaces ; 11(43): 39827-39840, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31597424

RESUMO

Self-terminated oligomer additives synthesized from bismaleimide and barbituric acid derivatives improve the safety and performance of lithium-ion batteries (LIBs). This study investigates the interface interaction of these additives and the cathode material. Two additives were synthesized by Michael addition (additive A) and aza-Michael addition (additive B). The electrochemical performances of bare and modified LiNi0.6Mn0.2Co0.2O2 (NMC622) materials are studied. The cycling stability and rate capability of NMC622 considerably improve on surface modification with additive B. According to the differential scanning calorimetry results, the exothermic heat of fully deliathiated NMC622 is dramatically decreased through surface modification with both additives. The electrode surface kinetics and interface interaction phenomena of the additives are determined through surface plasma resonance measurements in operando gas chromatography-mass spectroscopy (GCMS) and in situ soft X-ray absorption spectroscopy (XAS). The binding rate constant of additive B onto NMC622 particles is 1.2-2.3 × 104 M-1 s-1 in the temperature range of 299-311 K, which is ascribed to the strong binding affinity toward the electrode surface. This affinity enhances Li+ diffusion, which allows the electrode modified by additive B to provide high electrochemical performance with superior thermal stability. In operando GCMS reveals that gas evolution due to the electrolyte degradation at the NMC622 surface contributes to safety hazards in the bare NMC622 material. In situ soft XAS indicates the occurrence of structural transformation in the bare NMC622 material after it is fully charged and at elevated temperatures. The NMC622 material is stabilized by incorporating additives. The unique performance of additive B can be attributed to its linear structure that allows superior electrode surface adhesion compared with that of additive A. Therefore, this study presents an optimized working principle of self-terminated oligomers, which can be developed and applied to improve the safety and performance of LIBs.

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