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1.
J Infect Chemother ; 30(4): 277-285, 2024 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-38242285

RESUMEN

The Japanese surveillance committee conducted a third nationwide surveillance of antimicrobial susceptibility of acute uncomplicated cystitis at 55 facilities throughout Japan between April 2020 and September 2021. In this surveillance, we investigated the susceptibility of Escherichia coli (E. coli), Klebsiella pneumoniae (K. pneumoniae), and Staphylococcus saprophyticus (S. saprophyticus) for various antimicrobial agents by isolating and culturing bacteria from urine samples. In total, 823 strains were isolated from 848 patients and 569 strains of target bacteria, including E. coli (n = 529, 92.9 %), K. pneumoniae (n = 28, 4.9 %), and S. saprophyticus (n = 12, 2.2 %) were isolated. The minimum inhibitory concentrations of 18 antibacterial agents were determined according to the Clinical and Laboratory Standards Institute manual. In premenopausal patients, there were 31 (10.5 %) and 20 (6.8 %) fluoroquinolone (FQ)-resistant E. coli and extended-spectrum ß-lactamase (ESBL)-producing E. coli, respectively. On the other hand, in postmenopausal patients, there were 75 (32.1 %) and 36 (15.4 %) FQ-resistant E. coli and ESBL-producing E. coli, respectively. The rate of FQ-resistant E. coli and ESBL-producing E. coli in post-menopausal women was higher than that for our previous nationwide surveillance (20.7 % and 32.1 %: p = 0.0004, 10.0 % and 15.4 %; p = 0.0259). For pre-menopausal women, there was no significant difference in the rate of FQ-resistant E. coli and ESBL-producing E. coli between this and previous reports, but the frequency of FQ-resistant E. coli and ESBL-producing E. coli exhibited a gradual increase. For appropriate antimicrobial agent selection and usage, it is essential for clinicians to be aware of the high rate of these antimicrobial-resistant bacteria in acute uncomplicated cystitis in Japan.


Asunto(s)
Cistitis , Escherichia coli , Humanos , Femenino , Klebsiella pneumoniae , Staphylococcus saprophyticus , Japón/epidemiología , Bacterias , Fluoroquinolonas , Cistitis/tratamiento farmacológico , Cistitis/epidemiología , Cistitis/microbiología
2.
Intern Med ; 2023 Oct 06.
Artículo en Inglés | MEDLINE | ID: mdl-37813616

RESUMEN

Infected aortic aneurysms are rare, and have a high mortality rate. Although not a major pathogen, Streptococcus pyogenes has been reported to cause infected aortic aneurysms. In the present case, the patient was hospitalized for pyogenic flexor tenosynovitis with S. pyogenes bacteremia. Despite drainage of the abscess around the flexor tendon and effective antimicrobial therapy, infected aneurysms developed in the abdomen and ascending aorta. Because of their rapid enlargement, these aneurysms were treated with in situ reconstruction. Although rare, the possibility that S. pyogenes is the causative pathogen of infected aortic aneurysms should be considered.

3.
J Infect Chemother ; 29(11): 1011-1016, 2023 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-37553046

RESUMEN

Neisseria gonorrhoeae is one of the important pathogens of sexually transmitted infections. N. gonorrhoeae is rapidly becoming antimicrobial resistant, and there are few drugs that are effective in the initial treatment of gonorrhea. To understand the trends of antimicrobial susceptibility of N. gonorrhoeae, the Surveillance Committee of the Japanese Society of Infectious Diseases, the Japanese Society for Chemotherapy, and the Japanese Society of Clinical Microbiology conducted the third nationwide antimicrobial susceptibility surveillance of N. gonorrhoeae isolated from male urethritis. The specimens were collected from male patients with urethritis at 30 facilities from May 2016 to July 2017. From the 159 specimens collected, 87 N. gonorrhoeae strains were isolated, and 85 were tested for susceptibility to 21 antimicrobial agents. All strains were non-susceptible to penicillin G. Seven strains (8.2%) were ß-lactamase-producing strains. The rates of susceptibility to cefixime and cefpodoxime were 96.5% and 52.9%, respectively. Three strains were non-susceptible with a minimum inhibitory concentration (MIC) of 0.5 mg/L for cefixime. None of the strains were resistant to ceftriaxone or spectinomycin. The susceptibility rate for ciprofloxacin was 23.5% (20 strains), and no strains showed intermediate susceptibility. The susceptibility rate against azithromycin was 81.2%, with one strain isolated with a MIC of 8 mg/L against azithromycin. The results of this surveillance indicate that ceftriaxone and spectinomycin, which are currently recommended for gonococcal infections in Japan, appear to be effective. It will be necessary to further expand the scale of the next surveillance to understand the current status of drug-resistant N. gonorrhoeae in Japan.


Asunto(s)
Antiinfecciosos , Gonorrea , Uretritis , Humanos , Masculino , Neisseria gonorrhoeae , Antibacterianos/farmacología , Antibacterianos/uso terapéutico , Cefixima/farmacología , Cefixima/uso terapéutico , Ceftriaxona/uso terapéutico , Azitromicina/uso terapéutico , Espectinomicina/farmacología , Espectinomicina/uso terapéutico , Uretritis/tratamiento farmacológico , Uretritis/epidemiología , Uretritis/microbiología , Japón/epidemiología , Gonorrea/tratamiento farmacológico , Gonorrea/epidemiología , Antiinfecciosos/uso terapéutico , Pruebas de Sensibilidad Microbiana
4.
J Med Chem ; 66(12): 8054-8065, 2023 06 22.
Artículo en Inglés | MEDLINE | ID: mdl-37257133

RESUMEN

Pancreatic tumors grow in an "austerity" tumor microenvironment characterized by nutrient deprivation and hypoxia. This leads to the activation of adaptive pathways in pancreatic cancer cells, promoting tolerance to nutrition starvation and aggressive malignancy. Conventional anticancer drugs are often ineffective against tumors that grow in such austerity condition. Plumbagin, a plant-derived naphthoquinone, has shown potent preferential cytotoxicity against pancreatic cancer cells under nutrient-deprived conditions. Therefore, we synthesized a series of plumbagin derivatives and found that 2-(cyclohexylmethyl)-plumbagin (3f) was the most promising compound with a PC50 value of 0.11 µM. Mechanistically, 3f was found to inhibit the PI3K/Akt/mTOR signaling pathways, leading to cancer cell death under nutrient-deprived conditions. In vivo studies using pancreatic cancer xenograft mouse models confirmed the efficacy of 3f, demonstrating significant inhibition of tumor growth in a dose-dependent manner. Compound 3f represents a highly promising lead for anticancer drug development based on an antiausterity strategy.


Asunto(s)
Antineoplásicos Fitogénicos , Naftoquinonas , Neoplasias Pancreáticas , Humanos , Animales , Ratones , Antineoplásicos Fitogénicos/farmacología , Fosfatidilinositol 3-Quinasas , Naftoquinonas/farmacología , Naftoquinonas/uso terapéutico , Neoplasias Pancreáticas/tratamiento farmacológico , Línea Celular Tumoral , Ensayos de Selección de Medicamentos Antitumorales , Proliferación Celular , Microambiente Tumoral , Neoplasias Pancreáticas
5.
J Colloid Interface Sci ; 641: 82-90, 2023 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-36924548

RESUMEN

The activity-enhancement of a new-generation catalyst focuses on the collegial approach among specific solids which exploit the mutual coactions of these materials for HER applications. Strategic manipulation of these solid interfaces typically reveals unique electronic states different from their pure phases, thus, providing a potential passage to create catalysts with excellent activity and stability. Herein, the formation of the NiWO4-NiO interface has been designed and synthesized via a three-step method. This strategy enhances the chance of the formation of abundant heterointerfaces due to the fine distribution of NiWO4 nanoparticles over Ni(OH)2 sheets. NiWO4-NiO has superior HER activity in an alkaline (1 M KOH) electrolyte with modest overpotentials of 68 mV at 10 mA cm-2 current density. The catalyst is highly stable in an alkaline medium and negligible change was observed in the current density even after 100 h of continuous operation. This study explores a unique method for high-performance hydrogen generation by constructing transition metal-oxides heterojunction. The XPS studies reveal an electronic redistribution driven by charge transfer through the NiWO4-NiO interface. The density functional theory (DFT) calculations show that the NiWO4-NiO exhibits a Pt-like activity with the hydrogen Gibbs free energy (ΔGH*) value of 0.06 eV compared to the Pt(ΔGH* = -0.02 eV).

6.
Ecotoxicol Environ Saf ; 243: 113985, 2022 Sep 15.
Artículo en Inglés | MEDLINE | ID: mdl-36027712

RESUMEN

The present study aimed to assess the in-vitro toxicity of a popular azodye, Eriochrome Black T (EBT) which may be an environmental hazard causing water pollution if released by textile industries as waste effluents to nearby water ponds. We explored the toxic potential of EBT at 200, 400 and 800 µg/ml concentrations, which were selected based on quantification of EBT present in the pond water near carpet industries. We investigated the permeability of EBT across the organ barriers and found it to be 6.48 ± 0.44% at the highest concentration. EBT also showed up to 26.46 ± 0.533% hemolytic potential on human RBCs. MTT assay revealed toxicity of up to 64.9 ± 10.12%. A dose-dependent increase in intracellular ROS levels and Caspase 3/7 activity was observed and confocal microscopy also demonstrated a similar trend of cellular apoptosis indicating ROS mediated induction of apoptosis as a mechanism of EBT induced cytotoxicity. After establishing the toxicity of EBT, an innovative nano-photocatalytic approach for dye remediation was applied by using as synthesized Mf-NGr-CNTs-SnO2 heterostructures. This catalyst showed dye degradation potential of up to 82% in 2 h in the presence of sun light. The degraded dye products were tested to have up to 30% reduced cellular toxicity as compared to the parent compound. This work successfully establishes the toxicity of EBT along with devising an innovative approach towards dye degradation where the catalyst is adhered on melamine foam and not being mixed in the effluents directly, thereby, reducing the possibility of catalyst being leached out into the river water.


Asunto(s)
Compuestos Azo , Industria Textil , Compuestos Azo/química , Compuestos Azo/toxicidad , Colorantes/química , Humanos , Especies Reactivas de Oxígeno , Textiles , Agua
7.
ACS Nano ; 16(3): 4861-4875, 2022 Mar 22.
Artículo en Inglés | MEDLINE | ID: mdl-35188366

RESUMEN

Water splitting using renewable energy resources is an economic and green approach that is immensely enviable for the production of high-purity hydrogen fuel to resolve the currently alarming energy and environmental crisis. One of the effective routes to produce green fuel with the help of an integrated solar system is to develop a cost-effective, robust, and bifunctional electrocatalyst by complete water splitting. Herein, we report a superhydrophilic layered leaflike Sn4P3 on a graphene-carbon nanotube matrix which shows outstanding electrochemical performance in terms of low overpotential (hydrogen evolution reaction (HER), 62 mV@10 mA/cm2, and oxygen evolution reaction (OER), 169 mV@20 mA/cm2). The outstanding stability of HER at least for 15 days at a high applied current density of 400 mA/cm2 with a minimum loss of potential (1%) in acid medium infers its potential compatibility toward the industrial sector. Theoretical calculations indicate that the decoration of Sn4P3 on carbon nanotubes modulates the electronic structure by creating a higher density of state near Fermi energy. The catalyst also reveals an admirable overall water splitting performance by generating a low cell voltage of 1.482 V@10 mA/cm2 with a stability of at least 65 h without obvious degradation of potential in 1 M KOH. It exhibited unassisted solar energy-driven water splitting when coupled with a silicon solar cell by extracting a high stable photocurrent density of 8.89 mA/cm2 at least for 90 h with 100% retention that demonstrates a high solar-to-hydrogen conversion efficiency of ∼10.82%. The catalyst unveils a footprint for pure renewable fuel production toward carbon-free future green energy innovation.

8.
Dalton Trans ; 51(5): 2019-2025, 2022 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-35029620

RESUMEN

Electrocatalytic water splitting is one of the key technologies for future energy systems envisioned for the storage of energy obtained from variable renewables and green fuels. The development of efficient, durable, Earth-abundant and cheap electrocatalysts for the oxygen evolution reaction is a scorching area of research. The oxygen evolution reaction has huge potential for fuel cell and metal-air battery applications. Herein, we reported interfacially interacted and uniformly decorated Co3O4-NiO hybrid nanostructures formed by a metal-organic framework (Co2-BDC(OH)2) using BDC as a linker to the metal center. The fine nanosheets of Co2-BDC(OH)2 were first uniformly grown over the honeycomb-like structure of nickel foam (NF). After controlled calcination of these nanosheets/NF composites, a uniformly decorated, binder-free Co3O4-NiO/NF electrocatalyst was synthesized. The transformation of Co2-BDC(OH)2/NF into Co3O4-NiO/NF was characterized by several techniques such as powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy, transmission electron microscopy, etc. The catalyst exhibits a low overpotential of 311 mV vs. RHE at 10 mA cm-2 current density. The catalyst also shows long-term stability (24 h) with a Tafel slope value of 90 mV dec-1. The obtained experimental results are also in-line with the theoretical data acquired from model systems.

9.
J Infect Chemother ; 28(1): 1-5, 2022 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-34580009

RESUMEN

The Urogenital Sub-committee and the Surveillance Committee of the Japanese Society of Chemotherapy, The Japanese Association for Infectious Diseases, and the Japanese Society for Clinical Microbiology conducted the second nationwide surveillance of the antimicrobial susceptibility of Chlamydia trachomatis. In this second surveillance study, clinical urethral discharge specimens were collected from patients with urethritis in 26 hospitals and clinics from May 2016 to July 2017. Based on serial cultures, the minimum inhibitory concentration (MIC) could be determined for 41 isolates; the MICs (MIC90) of ciprofloxacin, levofloxacin, tosufloxacin, sitafloxacin, doxycycline, minocycline, erythromycin, clarithromycin, azithromycin and solithromycin were 2 µg/ml (2 µg/ml), 1 µg/ml (0.5 µg/ml), 0.25 µg/ml (0.25 µg/ml), 0.125 µg/ml (0.063 µg/ml), 0.125 µg/ml (0.125 µg/ml), 0.25 µg/ml (0.25 µg/ml), 0.031 µg/ml (0.031 µg/ml), 0.25 µg/ml (0.125 µg/ml), and 0.016 µg/ml (0.008 µg/ml), respectively. In summary, this surveillance project did not identify any strains resistant to fluoroquinolone, tetracycline, or macrolide agents in Japan. In addition, the MIC of solithromycin was favorable and lower than that of other antimicrobial agents. However, the MIC of azithromycin had a slightly higher value than that reported in the first surveillance report, though this might be within the acceptable margin of error. Therefore, the susceptibility of azithromycin, especially, should be monitored henceforth.


Asunto(s)
Chlamydia trachomatis , Uretritis , Antibacterianos/farmacología , Antibacterianos/uso terapéutico , Azitromicina/farmacología , Farmacorresistencia Bacteriana , Humanos , Japón/epidemiología , Masculino , Pruebas de Sensibilidad Microbiana , Uretritis/tratamiento farmacológico , Uretritis/epidemiología
10.
ACS Appl Mater Interfaces ; 13(46): 55281-55291, 2021 Nov 24.
Artículo en Inglés | MEDLINE | ID: mdl-34779604

RESUMEN

One of the major objectives of using the improved Hummers' method was to exfoliate the graphene layers by oxidizing and thereafter reducing them to obtain highly conductive reduced graphene layers, which can be used in the construction of electronic devices or as a part of catalyst composites in energy conversion reactions. Herein, we have employed a similar idea to exfoliate the layered double hydroxide (LDH), which is proposed as a promising material for the oxygen evolution reaction (OER) electrocatalysis. Usually, the efficiency of these materials is largely restricted due to their sheetlike morphology, which is susceptible to stacking. In this work, NiFe-LDH sheets were fabricated on nickel foam in a one-step co-precipitation technique and their ultrathin nanosheets (∼2 nm) are obtained by in situ oxygen-plasma-controlled exfoliation. In addition, the oxygen vacancies in exfoliated sheets were generated by a chemical reduction method that further improved the electronic conductivity and overall electrocatalytic performance of the catalyst. This approach can address the limitations of NiFe-LDH, such as poor conductivity and low stability, making it more efficient for electrocatalysis. It is also observed that the catalyst having 60 s O-plasma exposure after chemical reduction, i.e., NiFe-OOHOV, outperformed remaining electrocatalysts and exhibited superior OER activity with a low overpotential of 330 mV to achieve a high current density of 50 mA cm-2. The catalyst also displayed an ECSA-normalized OER overpotential of 288 mV at a current density of 10 mA cm-2 and exhibited excellent long-term stability (120 h) in an alkaline electrolyte. Remarkably, ultrathin defect-rich catalyst continuously produced O2, resulting in a high faradaic efficiency of 98.1% for the OER.

11.
Br J Neurosurg ; : 1-6, 2021 Sep 23.
Artículo en Inglés | MEDLINE | ID: mdl-34553665

RESUMEN

BACKGROUND: Postoperative intracranial complications are rare in spine surgery not including cranial procedures. We describe an uncommon case of pseudohypoxic brain swelling (PHBS) and secondary hydrocephalus after transforaminal lumbar interbody fusion (TLIF) presenting as impaired consciousness and repeated seizures. CASE PRESENTATION: A 65-year-old man underwent L4-5 TLIF for lumbar spondylolisthesis and began experiencing generalized seizures immediately postoperatively. Computed tomography (CT) revealed diffuse cerebral edema-like hypoxic ischemic encephalopathy. He was transported to our hospital, at which time epidural drainage was halted and anti-edema therapy was commenced. His impaired consciousness improved. However, he suffered secondary hydrocephalus due to continuous bleeding from a dural defect and spinal epidural fluid collection 3 months later. Following the completion of dural repair and insertion of a ventriculoperitoneal shunt, his neurologic symptoms and neuroimaging findings improved significantly. CONCLUSIONS: PHBS can be considered in patients with unexpected neurological deterioration following lumbar spine surgery even with the absence of documented durotomy. This might be due to postoperative intracranial hypotension-associated venous congestion, and to be distinguished from the more common postoperative cerebral ischemic events-caused by arterial or venous occlusions-or anesthetics complications.

12.
J Phys Chem Lett ; 12(28): 6574-6581, 2021 Jul 22.
Artículo en Inglés | MEDLINE | ID: mdl-34242023

RESUMEN

In energy storage-device it is highly crucial to develop durable electrode materials having high specific capacitance and superior energy density without disturbing its inherent flexibility. Herein, we demonstrate three-dimensional graphene oxide decorated monodispersed hollow urchin γ-MnS (γ-MnS@3DG) via proficient one-step solvothermal method. The designed material delivers a remarkable capacitance of 858 F g-1 at 1 A g-1. A flexible solid state asymmetric supercapacitor (ASCs) device assembled using surface activated carbon cloth (CC) decorated with γ-MnS@3DG as positive and three-dimension graphene on carbon cloth (3DG@CC) as negative electrode, (γ-MnS@3DG//3DG). The device delivers 26 Wh kg-1 energy density at power density 500 W kg-1 @ 1A g-1 and retains favorable energy density 17.8 Wh kg-1 at an ultrahigh power density of 1500 W kg-1@3 A g-1. This carbon embedded transition-metal sulfide (TMS) based ASC demonstrates eminent mechanical flexibility under rigorous bending states maintaining invariant performance.

13.
ACS Nano ; 15(3): 5586-5599, 2021 Mar 23.
Artículo en Inglés | MEDLINE | ID: mdl-33625208

RESUMEN

Water splitting via an electrochemical process to generate hydrogen is an economic and green approach to resolve the looming energy and environmental crisis. The rational design of multicomponent materials with seamless interfaces having robust stability, facile scalability, and low-cost electrocatalysts is a grand challenge to produce hydrogen by water electrolysis. Herein, we report a superhydrophilic homogeneous bimetallic phosphide of Ni2P-CuP2 on Ni-foam-graphene-carbon nanotubes (CNTs) heterostructure using facile electrochemical metallization followed by phosphorization without any intervention of metal-oxides/hydroxides. This bimetallic phosphide shows ultralow overpotentials of 12 (HER, hydrogen evolution reaction) and 140 mV (OER, oxygen evolution reaction) at current densities of 10 and 20 mA/cm2 in acidic and alkaline mediums, respectively. The excellent stability lasts for at least for 10 days at a high current density of 500 mA/cm2 without much deviation, inferring the practical utilization of the catalyst toward green fuel production. Undoubtedly, the catalyst is capable enough for overall water splitting at a very low cell voltage of 1.45 V @10 mA/cm2 with an impressive stability of at least 40 h, showing a minimum loss of potential. Theoretical study has been performed to understand the reaction kinetics and d-band shifting among metal atoms in the heterostructure (Ni2P-CuP2) that favor the HER and OER activities, respectively. In addition, the catalyst demonstrates an alternate transformation of solar energy to green H2 production using a standard silicon solar cell. This work unveils a smart design and synthesizes a highly stable electrocatalyst against an attractive paradigm of commercial water electrolysis for renewable electrochemical energy conversion.

14.
Mater Sci Eng C Mater Biol Appl ; 120: 111757, 2021 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-33545898

RESUMEN

As a paper-like membrane composed of single-walled carbon nanotube (SWCNT), buckypaper possesses high conductivity, ideal flexibility, large surface area, great thermal/chemical stability and biocompatibility, which has manifested its potential as an alternative support material. However, due to the lack of defects, high quality SWCNT synthesized by arc-discharge method is difficult to be modified with metal nanoparticles for electro-catalysis. In this paper, a novel green strategy has been developed to fabricate SWCNT buckypaper decorated with Cu/reduced graphene oxide (Cu/rGO-BP) for the first time, in which graphene oxide functions as the intermediate between SWCNT and Cu nanoparticles. The fabricated Cu/rGO-BP was applied as a flexible electrode for electrochemical glucose detection. The electrode exhibited excellent electro-catalytic activity for glucose oxidation. The sensor based on Cu/rGO-BP performed a high upper limit of linear range (25 mM), which is close to commercial glucose sensors. The proposed strategy for Cu/rGO-BP fabrication can be extended to modify buckypaper with other metal or metal oxide nanoparticles, and thus opens an innovative route to potential practical applications of flexible buckypaper in wearable bioelectronics.


Asunto(s)
Técnicas Biosensibles , Grafito , Técnicas Electroquímicas , Electrodos , Glucosa
15.
Org Lett ; 23(5): 1703-1708, 2021 03 05.
Artículo en Inglés | MEDLINE | ID: mdl-33577338

RESUMEN

In this contribution, we propose a new synthetic approach to tetrodotoxin (TTX), one of the most famous marine toxins that, after first preparing a functionalized linear substrate, forms a cyclohexane core from the substrate utilizing our mercuric triflate (Hg(OTf)2)-catalyzed cycloisomerization reaction. The concept was applied to the synthesis of 11-nor-6,7,8-trideoxyTTX and 11-nor-4,9-anhydro-6,7,8-trideoxyTTX, which are unnatural TTX analogues, demonstrating the validity of our new approach.

16.
ACS Appl Mater Interfaces ; 12(52): 57898-57906, 2020 Dec 30.
Artículo en Inglés | MEDLINE | ID: mdl-33326214

RESUMEN

Hydrogen is one of the cleanest forms of energy carrier which can solve the twin problem of exhaustion of fossil fuels and climate change. The exploration of low-cost and earth-abundant electrocatalysts for hydrogen generation process is an emerging area of research. Profound catalyst tailoring with mutually contrast phases on a porous support for crafting large hydrogen evolution reaction (HER) active sites increases the catalytic activity in many folds. Herein, a porous silica-supported molybdenum phosphide and molybdenum carbide nanoparticle (SiMoCP) has been synthesized. The intermingled porous molybdenum carbide and molybdenum phosphide nanohybrid shows excellent catalytic activity toward hydrogen evolution. Such a modified nanostructured electrocatalyst enhances the electrode-electrolyte interaction and suppresses the charge transfer resistance. As a result, the electrocatalyst (SiMoCP) accomplishes very high HER activity with an onset potential of 53 mV and an overpotential of 88 mV at a current density of 10 mA cm-2 in the acidic medium. Furthermore, the SiMoCP catalyst showed a Tafel slope value of 37 mV dec-1 with long-term durability of 5000 cycles.

17.
Nat Commun ; 11(1): 5923, 2020 Nov 23.
Artículo en Inglés | MEDLINE | ID: mdl-33230157

RESUMEN

Perovskite oxides can host various anion-vacancy orders, which greatly change their properties, but the order pattern is still difficult to manipulate. Separately, lattice strain between thin film oxides and a substrate induces improved functions and novel states of matter, while little attention has been paid to changes in chemical composition. Here we combine these two aspects to achieve strain-induced creation and switching of anion-vacancy patterns in perovskite films. Epitaxial SrVO3 films are topochemically converted to anion-deficient oxynitrides by ammonia treatment, where the direction or periodicity of defect planes is altered depending on the substrate employed, unlike the known change in crystal orientation. First-principles calculations verified its biaxial strain effect. Like oxide heterostructures, the oxynitride has a superlattice of insulating and metallic blocks. Given the abundance of perovskite families, this study provides new opportunities to design superlattices by chemically modifying simple perovskite oxides with tunable anion-vacancy patterns through epitaxial lattice strain.

18.
Nanotechnology ; 31(29): 295501, 2020 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-32120356

RESUMEN

Here we report a novel hybrid material consists of 2D graphitic carbon nitride (g-C3N4) and graphene heterostructure that exhibits piezoresistivity superior to graphene and potentially being used as a strain sensor. The g-C3N4 that contains periodically spaced triangular nanopores is used for improving the piezoresistivity of the sensor imparting change in the polarization upon application of strain. In this work, we have investigated graphene/g-C3N4 interfaced materials and quantified its piezoresistive effects through experimental analysis and density functional theory (DFT) based computational studies provide insights into the electronic structures of the hybrid interfaces. We have observed a linear response in electrical resistance for a wide range of uniaxial strains up to ∼25%. The observed increase in resistance upon application of strain corroborates with our computational finding of strain-dependent band gap opening. Further, it has been realized that band-gap opening occurs exclusively in the graphitic layer of the composite materials under strain. However, the g-C3N4 bands remain intact at the interface. The linearity and a considerably small gauge factor (1.89) make graphene/g-C3N4 a promising heterostructure material unlike conventional metal gauge sensor in wide strain pressure sensor devices.

19.
ACS Omega ; 4(9): 14155-14161, 2019 Aug 27.
Artículo en Inglés | MEDLINE | ID: mdl-31497736

RESUMEN

Natural fibrils derived from biomass were used as a template to synthesize uniformly decorated nanoparticles (10-12 nm) of molybdenum carbide (Mo2C) and molybdenum nitride (Mo2N) supported on carbon. The nanoparticles have been synthesized through the carburization and nitridation of molybdenum on cotton fibrils, using a high-temperature solid-state reaction. The catalyst exhibits an onset potential of 110 mV and an overpotential of 167 mV to derive a cathodic current density of 10 mA cm-2. The electrocatalyst also demonstrates excellent long-term durability of more than 2500 cycles in acidic media with a Tafel slope value of 62 mV dec-1.

20.
Bioorg Med Chem Lett ; 29(14): 1779-1784, 2019 07 15.
Artículo en Inglés | MEDLINE | ID: mdl-31097375

RESUMEN

Human pancreatic tumor cells have inherent ability to tolerate nutrition starvation which enables them to survive in the hypovascular tumor microenvironment. Discovery of agents that selectively inhibit the cancer cells' tolerance to nutrition starvation leading to cancer cell death is a new anti-austerity approach in anti-cancer drug discovery. A series of coumarins derivatives were synthesized and evaluated for their anti-austerity activity against PANC-1 human pancreatic cancer cell line. The compound 7-Hydroxy-2-oxo-2H-chromene-3-carboxylic acid (3-phenylpropyl)amide (2c) showed highly potent selective cytotoxicity against PANC-1 cells under nutrient-deprived conditions, with a PC50 value of 0.44 µM, without exhibiting toxicity in normal, nutrient-rich medium. Compound 2c caused dramatic alterations in PANC-1 cell morphology, leading to cell death. The compound 2c was found to inhibit PANC-1 cell migration and colony formation in a concentration-dependent manner. The compound 2c is a lead structure for the anti-austerity drug development against pancreatic cancer.


Asunto(s)
Antineoplásicos/uso terapéutico , Cumarinas/síntesis química , Descubrimiento de Drogas/métodos , Neoplasias Pancreáticas/tratamiento farmacológico , Antineoplásicos/farmacología , Cumarinas/química , Humanos
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