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1.
Phys Chem Chem Phys ; 26(29): 19900-19907, 2024 Jul 24.
Artículo en Inglés | MEDLINE | ID: mdl-38990130

RESUMEN

Hydroxylation reactions are important in biological processes and synthetic schemes. Many challenging hydroxylation reactions have been achieved using photoredox catalytic methods. For the oxidative hydroxylation of arylboronic acids, methylene blue has been used successfully as a photoredox catalyst to produce phenyl groups. Here we use broadband transient absorption spectroscopy to determine the mechanism of the photoredox catalytic reaction of methylene blue with phenylboronic acid in the presence of N,N-diisopropylethylamine. Our results show that the reaction proceeds through the triplet state of methylene blue in the presence of oxygen, generating superoxide radical anions. In addition, we observe dimerization of the methylene blue at typical catalytic loadings. As these dimers do not participate in the reaction, increasing the concentration of methylene blue is potentially detrimental to the overall yield.

2.
Clin Chim Acta ; 562: 119891, 2024 Jul 26.
Artículo en Inglés | MEDLINE | ID: mdl-39067500

RESUMEN

Sepsis is a life-threatening condition characterized by dysregulated host response to infection leading to organ dysfunction. Despite advances in understanding its pathology, sepsis remains a global health concern and remains a major contributor to mortality. Timely identification is crucial for improving clinical outcomes, as delayed treatment significantly impacts survival. Accordingly, biomarkers play a pivotal role in diagnosis, risk stratification, and management. This review comprehensively discusses various biomarkers in sepsis and their potential application in antimicrobial stewardship and risk assessment. Biomarkers such as white blood cell count, neutrophil to lymphocyte ratio, erythrocyte sedimentation rate, C-reactive protein, interleukin-6, presepsin, and procalcitonin have been extensively studied for their diagnostic and prognostic value as well as in guiding antimicrobial therapy. Furthermore, this review explores the role of biomarkers in risk stratification, emphasizing the importance of identifying high-risk patients who may benefit from specific therapeutic interventions. Moreover, the review discusses the emerging field of transcriptional diagnostics and metagenomic sequencing. Advances in sequencing have enabled the identification of host response signatures and microbial genomes, offering insight into disease pathology and aiding species identification. In conclusion, this review provides a comprehensive overview of the current understanding and future directions of biomarker-based approaches in sepsis diagnosis, management, and personalized therapy.

3.
J Fluoresc ; 2024 Feb 17.
Artículo en Inglés | MEDLINE | ID: mdl-38367156

RESUMEN

Fluorescent carbon dots (Trp-CDs) were prepared using tryptophan as precursor and were characterized on the basis of elemental analysis, powder-XRD, IR, Raman spectroscopy, 13C-NMR, UV-Vis, fluorescence and TEM. Trp-CDs exhibit poor fluorescence in 100% water but showed strong Aggregation Induced Emission (AIE) in ethanol and higher alcohols. The anion sensing study of Trp-CD revealed that it selectively detects CN- and Cr2O7-2 and from fluorescence quenching titration study, quenching constant, LOD and range of detection were evaluated. The emission life-time of Trp-CD before and after addition of CN- and Cr2O7-2 were measured, the decay curve before addition of anion was best fitted with a bi-exponential function with life-time of τ1 2.79 ns (10.74%) and τ2 18.93 ns (89.26%). The mechanistic study revealed that for CN-, the fluorescence quenching is due to its interaction with protons attached to surface functional groups and for Cr2O7-2, it is due to inner filter effect (IFE). Sensing strips were prepared by coating Trp-CDs onto various solid surfaces including agarose films and were used for detection of CN- and Cr2O7-. Trp-CD was found to be nontoxic and biocompatible and used as staining agent for Artemia and Bacteria (Bacillus Subtilis, Pseudomonas) and detection of CN- and Cr2O7-.

4.
Urologia ; 91(2): 261-269, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38159064

RESUMEN

INTRODUCTION: One of the most fatal urological malignancies is clear cell renal cell carcinoma (ccRCC), yet little is known about its pathophysiology or prognosis. This study is aimed at obtaining some novel biomarkers with diagnostic and prognostic meaning and may find out potential therapeutic targets for ccRCC. MATERIAL AND METHODS: Using three publically accessible ccRCC gene expression profiles acquired from the Gene Expression Omnibus database, differentially expressed genes (DEG) were discovered and function enrichment analyses were carried out. Gene Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis were conducted by using the DAVID tool and a protein-protein interaction (PPI) network was constructed and visualized by Cytoscape. Then we identified 10 hub genes using the cytohubba plugin of Cytoscape based on degree score. The mRNA and protein expression of hub genes was analyzed by GEPIA and Human Protein Atlas (HPA) database. Then, prognosis analysis of hub genes was conducted using GEPIA 3.0 which consists of data from The Cancer Genome Atlas (TCGA). RESULTS: We discovered 293 DEG which is highly enriched in several biological processes connected to immune-regulation and pathways linked to tumors, including HIF-1, PI3K-AKT, and metabolic pathways. In particular, C1QA, C1QB, FCER1G, and TYROBP were related to advanced clinical stage, high pathological grade, and poor survival in patients with ccRCC. CONCLUSIONS: Further molecular biological studies are required to confirm the role of the putative biomarkers in human ccRCC. Our work highlighted the hub genes and pathways involved in the progression of ccRCC.


Asunto(s)
Carcinoma de Células Renales , Biología Computacional , Neoplasias Renales , Carcinoma de Células Renales/genética , Humanos , Neoplasias Renales/genética , Pronóstico , Perfilación de la Expresión Génica , Regulación Neoplásica de la Expresión Génica
5.
Chemosphere ; 350: 141051, 2024 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-38159730

RESUMEN

Mixed-matrix membranes (MMMs) with an ideal polymer/hydrophilic flux enhancer interface considerably recuperates the separation and purification performance of membrane. In this direction, a novel CoFe2O4 functionalized natural clay-bentonite (CoFe2O4@BT) material as a compatible flux enhancer was synthesized for preparation of mixed matrix based in polyethersulfone (PES) matrix. Here, the influences of CoFe2O4@BT on the morphology and performance of the MMMs membranes were systematically investigated using various analytical techniques. Meanwhile, the water flux and sepration eficiency of the CoFe2O4@BT-PES membranes significantly enhanced due to the incorporation of CoFe2O4@BT that altered hydrophilicity, pore and surface characteristic features. The water flux as well as separation efficiency range up to 95%, 94.69%, 94.16% of Congo red (CR), Crystal violet (CV), and humic acid (HA) respectively. Meanwhile, the fouling parameters demonstrated that the CoFe2O4@BT-PES membranes exhibited better antifouling property in the long term experiment comparing with commercial polyamide membrane. CoFe2O4@BT material incorporated membranes showed less decline ratio and a better recovery ratio. The high rejection of dyes with a high permeation flux of the newly designed membranes indicated an amazing possibility for dye purification. In this study, a potential dye mechanism for composite membranes impacted by synthetic CoFe2O4@BT was also put forth. Within the context of application considerations for environmental protection, new materials stock in membranes show good potential for the separation of different organic contaminants.


Asunto(s)
Bentonita , Polímeros , Sulfonas , Purificación del Agua , Aguas Residuales , Membranas Artificiales , Purificación del Agua/métodos , Colorantes/química , Agua/química
6.
J Phys Chem Lett ; 14(50): 11268-11273, 2023 Dec 21.
Artículo en Inglés | MEDLINE | ID: mdl-38060441

RESUMEN

Radicals and other open-shell molecules play a central role in chemical transformations and redox chemistry. While radicals are often highly reactive, stable radical systems are desirable for a range of potential applications, ranging from materials chemistry and catalysis to spintronics and quantum information. Here we investigate the ultrafast properties of a stable radical system with temperature-dependent spin-tunable properties. This radical complex, Cu(II) hexaethyl tripyrrin-1,14-dione, accommodates unpaired electrons localized on both the copper metal center and the tripyrrolic ligand. The unusual combination of two unpaired electrons and high stability in this radical molecule enable switchable temperature-dependent spin coupling. Two-dimensional electronic spectroscopy measurements of Cu(II) hexaethyl tripyrrin-1,14-dione were collected at room temperature and at 77 K. At room temperature, the molecules are present as monomers and have short picosecond lifetimes. At 77 K, the molecules are present in a dimer form mediated by ferromagnetic and antiferromagnetic coupling. This reversible spin-driven dimerization changes the optical properties of the system, generating long-lived excitonic states.

7.
Med J Armed Forces India ; 79(3): 286-291, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37193516

RESUMEN

Background: Acute respiratory infections (ARIs) are responsible for considerable morbidity and mortality among children all over the world. Many of the etiologic agents of the infections especially viral go undiagnosed for lack of requisite facility and the cost factors. We have used a commercially available platform for diagnosis of ARIs in children receiving inpatient and outpatient services in a tertiary care centre. Methods: The framework of the study was prospective and observational. In this study, clinical samples of children suffering from ARIs were subjected to real-time multiplex PCR targeting both viral and bacterial pathogens. Results: Of 94 samples received at our centre (49 male and 45 female), the positivity for respiratory pathogens was detected in 50 (53.19%) samples. Clinical symptoms of patients and age distribution have been elaborated in text. A single pathogen (n = 29/50), two pathogens (15/50) and three pathogens (n = 6/50) were detected by multiplex RT-PCR. Of 77 isolates detected, maximum numbers were of human rhinovirus (HRV) (n = 14) (18.18%) Streptococcus pneumoniae (n = 14) (18.18%) followed by Staphylococcus aureus (n = 10) (12.98%). Conclusion: The epidemiology of ARIs considering viral etiologies is poorly understood due to less number of studies especially in Indian subcontinent. The advent of latest advanced molecular methods has made it possible to identify common respiratory pathogens and has contributed to cover the gap in existing knowledge.

8.
Urologia ; 90(2): 377-380, 2023 May.
Artículo en Inglés | MEDLINE | ID: mdl-36883382

RESUMEN

PURPOSE: International prostate symptom score (IPSS) is a complex questionnaire method for objective assessment of Lower urinary tract symptoms. So, there is a need to develop a simple and easy scoring system that could be easily used for illiterates and older aged patients. MATERIALS AND METHODS: It was a prospective observational study with 202 participants, conducted at the department of urology of a tertiary care hospital in eastern India. The patients more than 50 years of age, attending urology OPD with Lower urinary tract symptoms were included in the study. Printed IPSS and VPSS questionnaires were given to the patient to answer. RESULTS: Eighty-two percent (82%) of the higher education group and 97% of the lower education group needed assistance to answer IPSS questionnaires while 18% of the higher education group and 44% of the lower education group needed assistance to answer VPSS questionnaires. Sixty-four (64%) of patients in our study belong to the high education level while 36% of patients belong to the low education group. The mean age was 60.1 years. The mean IPSS and VPSS were 19 and 11 respectively. The mean PSA was 1.5 ng/ml. The time taken to fill VPSS questionnaire was much less than IPSS questionnaires. All the patients felt that VPSS was easier. Statistically significant (p-value < 0.05) correlation was found between total IPSS and total VPSS, Q2 IPSS and Q1 VPSS, Q7 IPSS and Q2 VPSS, Q5 IPSS and Q3 VPSS, and IPSS Qol and VPSS Qol. A negative correlation was found between Q3 VPSS and Qmax, and Q5 IPSS and Qmax. CONCLUSIONS: VPSS can be used as an alternative tool to IPSS to assess LUTS, which uses pictograms instead of questionnaires, even in patients with limited education.


Asunto(s)
Síntomas del Sistema Urinario Inferior , Hiperplasia Prostática , Evaluación de Síntomas , Estudios Prospectivos , Humanos , Masculino , Persona de Mediana Edad , Encuestas y Cuestionarios , Anciano , Anciano de 80 o más Años , India , Evaluación de Síntomas/métodos
9.
Spectrochim Acta A Mol Biomol Spectrosc ; 286: 121956, 2023 Feb 05.
Artículo en Inglés | MEDLINE | ID: mdl-36252303

RESUMEN

Hand-held, compact and portable sensors for on-site detection of environmental contaminants are in high demand for industry 4.0. Here, we have developed a sensor based on luminescent organic-inorganic metal halide hybrid perovskites nanocrystals (CH3NH3PbBr3) with p-xylylenediamine as an additional capping agent for highly sensitive and selective detection of picric acid (PA), with a good linear range of 1.8 µM-14.3 µM achieving detection of limit (LOD) of 0.3 µM. The electrostatic interaction between PA and the capping ligand of perovskite nanocrystals resulted in significant fluorescence quenching, as revealed by the steady-state and time-resolved spectroscopy. The applicability of the developed sensor for PA detection was validated with a 3D printed device integrating surface mounting device (SMD) and paper microfluidics. This prototype device was successfully applied as a fluorescence turn-off sensor to detect PA, showing great potential for on-site detection. This 3D-printed paper-based microfluidic optical sensor proved very efficient for naked-eye detection of PA with an inbuilt excitation source, avoiding the requirement of expensive and complex instrumentation.


Asunto(s)
Electrones , Nanopartículas del Metal , Nanopartículas del Metal/química , Impresión Tridimensional
10.
Sci Rep ; 12(1): 17119, 2022 10 12.
Artículo en Inglés | MEDLINE | ID: mdl-36224315

RESUMEN

Globally 3 billion people are consuming water with moderately high concentrations of fluoride and arsenic. The development of a simple point of care (PoC) device or home device for the detection of fluoride/arsenic ensures safety before consuming water. Till date, lateral flow assay (LFA) based PoC devices can detect nucleic acids, viruses and diseases. An aluminium complex of rhodamine B functionalized oxacalix[4]arene (L) was designed to execute the LFA-based PoC device. Initially, Al3+ and Fe3+ ions were involved in complexation with the rhodamine B functionalized oxacalix[4]arene (L), resulting C1 (L-Al3+) and C2 (L-Fe3+) complexes respectively. The receptor L, as well as the probes (C1, C2), were characterized thoroughly using mass spectroscopy, FTIR, NMR, and EA. C1 and C2 were further utilized as recyclable probes for the detection of aqueous fluoride (21 ppb) and arsenate (1.92 ppb) respectively. The computational calculation indicates that upon complexation, the spirolactam ring opening at the rhodamine B site leads to optoelectronic changes. The consistency of LFA-based portable sensing device has been tested with water samples, synthetic fluoride standards and dental care products like toothpaste and mouthwash with concentrations ≥ 3 ppm. Moreover, fixed cell imaging experiments were performed to ascertain the in-vitro sensing phenomena.


Asunto(s)
Arsénico , Ácidos Nucleicos , Aluminio , Arseniatos , Colorimetría/métodos , Fluoruros , Humanos , Antisépticos Bucales , Pastas de Dientes , Agua/química
11.
Med J Armed Forces India ; 78(Suppl 1): S266-S268, 2022 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-36147403

RESUMEN

Paragonimiasis is a crustacean-borne parasitic zoonosis caused by lung fluke or Paragonimus. Several endemic foci of paragonimiasis have been discovered in Northeastern India. Chronic pulmonary infection with Paragonimus is characterized by hemoptysis, which is usually mistaken for Tuberculosis (TB). Paragonimiasis is acquired by eating raw, undercooked, or pickled crabs or crayfish containing encysted metacercariae of Paragonimus. Infection can usually be confirmed by finding Paragonimus eggs in sputum or bronchoalveolar lavage. We present a rare case of paragonimiasis masquerading as hypereosinophilia, asthma, and intracerebral hemorrhage for the last three years. Paragonimiasis is a rare cause of hemoptysis outside endemic regions. A strong index of suspicion is required to diagnose paragonimiasis outside the endemic areas. Diagnosis is usually delayed because of similarity of presentation to TB. Our patient was symptomatic with hemoptysis for three years. He gave history of eating raw crayfish and crabs while on leave to his native village in Nagaland. Diagnosis was confirmed on microscopy by detection of Paragonimus ova in sputum and bronchoalveolar lavage specimens. Symptoms resolved on treatment with praziquantel (25 mg/kg TDS for three days). Patient became symptom-free after a week of treatment.

12.
Sci Rep ; 12(1): 9061, 2022 05 31.
Artículo en Inglés | MEDLINE | ID: mdl-35641637

RESUMEN

In this work, we report, the synthesis of Boron and Sulfur co-doped graphene quantum dots (BS-GQDs) and its applicability as a label-free fluorescence sensing probe for the highly sensitive and selective detection of dopamine (DA). Upon addition of DA, the fluorescence intensity of BS-GQDs were effectively quenched over a wide concentration range of DA (0-340 µM) with an ultra-low detection limit of 3.6 µM. The quenching mechanism involved photoinduced electron transfer process from BS-GQDs to dopamine-quinone, produced by the oxidization of DA under alkaline conditions. The proposed sensing mechanism was probed using a detailed study of UV-Vis absorbance, steady state and time resolved fluorescence spectroscopy. The high selectivity of the fluorescent sensor towards DA is established. Our study opens up the possibility of designing a low-cost biosensor which will be suitable for detecting DA in real samples.


Asunto(s)
Grafito , Puntos Cuánticos , Boro , Dopamina/química , Colorantes Fluorescentes/química , Grafito/química , Puntos Cuánticos/química , Azufre
13.
J Fluoresc ; 32(4): 1425-1433, 2022 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-35438369

RESUMEN

A pyrene functionalized oxacalix[4]arene architecture (DPOC) was utilized as a fluorescence probe for selective recognition of cyanide ions. The receptor DPOC shows excellent selectivity towards cyanide ion with a red shift of 108 nm in absorption band along with a significant change in colour from light yellow to pink. The fluorescence titration experiments further confirm the lower limit of detection as 1.7µM with no significant influences of competing anions. 1 H-NMR titration experiments support the deprotonation phenomena, as the -NH proton disappears upon successive addition of cyanide ions. The DFT calculation also indicates a certain increment of -NH bond length upon interaction with cyanide ions. The spectral properties as well as colour of DPOC-CN- system may be reversed upon the addition of Ag+/ Cu2+ ions up to 5 consecutive cycles. Moreover, DPOC coated "test strips" were prepared for visual detection of cyanide ions.


Asunto(s)
Colorimetría , Cianuros , Aniones , Colorantes Fluorescentes/química , Pirenos
14.
Dalton Trans ; 49(22): 7459-7466, 2020 Jun 14.
Artículo en Inglés | MEDLINE | ID: mdl-32432588

RESUMEN

An oxacalix[4]arene-Ce(iii) complex viz. L-Ce(III) has been introduced for the selective detection of As(v) and Cr(vi) oxyanions in aqueous medium. The binding mode of L-Ce(III) + AsO43-/CrO42- was completely investigated with fluorometric titration, time resolve fluorescent decay and FTIR analyses. Photoinduced electron transfer (PET) and chelation-enhanced fluorescence (CHEF) play an important role in the sensing of these oxyanions. The characteristic fluorescence of the L-Ce(III) complex has been quenched by AsO43- and CrO42- through cascading the ligating sites. Cyclic voltammetry (CV) experiments with various scan rates suggest that the electrochemical processes on the electrodes were controlled by diffusion. Both the analytes exhibit a lower limit of detection (LOD) below their standard EPA permissible limits. Moreover, the probe successfully detects the oxyanions in environmental real samples with excellent recovery ranging from 97 to 101%.


Asunto(s)
Arsénico/análisis , Calixarenos/química , Cromo/análisis , Complejos de Coordinación/química , Colorantes Fluorescentes/química , Fenoles/química , Contaminantes Químicos del Agua/química , Agua/química , Aniones/análisis , Complejos de Coordinación/síntesis química , Cristalografía por Rayos X , Colorantes Fluorescentes/síntesis química , Modelos Moleculares , Estructura Molecular
15.
Indian J Crit Care Med ; 22(10): 753-756, 2018 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-30405291

RESUMEN

Autoimmune hemolytic anemia (AIHA) is a very rare cause of anemia in a case of malaria and drug-induced AIHA is even rarer. A 50-year old patient with a history of fever for 8 days was diagnosed with a case of complicated malaria with mixed infection having initial parasite index of 45%. He showed good response on initial therapy with artesunate (parasite count reduced to <1%) but his haemoglobin (Hb) continued to drop from 12 g% to 4.9 g% over a course of 11 days. Direct coombs test was positive with reduced haptoglobin and increased lactate dehydrogenase suggesting AIHA. The patient was put on steroids and transfused with saline washed O-negative blood. He gradually recovered over 8 weeks with Hb level rising up to 12 g%. This is a rare case of AIHA following treatment of severe malaria with parenteral artesunate suggesting of the drug immune-related mechanism.

16.
Colloids Surf B Biointerfaces ; 167: 126-133, 2018 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-29635135

RESUMEN

We report a one pot green strategy for the synthesis of carbon dots using tulsi leaves and their potential application in sensing of Cr(VI) selectively. The detection mechanism is based on the phenomenon called inner filter effect (IFE) and a good linear static quenching was observed in the range of 1.6 µM to 50 µM with a detection limit of 4.5 ppb. The reversible switching in fluorescence has been tested and a good recovery in fluorescence was observed up to three consecutive cycles upon addition of ascorbic acid as reducing agent. Also the low toxicity, high fluorescence and photostabilty of the CDs make them excellent imaging and patterning agent. The acid and alkali resistant property of these CDs makes it suitable for real sample analysis. The fluorescent CDs were applied for successful detection of Cr(VI) in water with spike-recoveries ranging from 93 to 99%.


Asunto(s)
Carbono/química , Cromo/análisis , Fluorescencia , Extractos Vegetales/química , Puntos Cuánticos/química , Cromo/química , Colorantes Fluorescentes/química , Microscopía Electrónica de Transmisión , Ocimum sanctum/química , Hojas de la Planta/química , Espectrometría de Fluorescencia , Termogravimetría , Contaminantes Químicos del Agua/análisis , Contaminantes Químicos del Agua/química
17.
J Hazard Mater ; 353: 190-203, 2018 07 05.
Artículo en Inglés | MEDLINE | ID: mdl-29674094

RESUMEN

Here we demonstrate, a simple and solvent-free synthetic route for the production of FeS/Fe(0) functionalized graphene nanocomposite (G-Fe) via a one-step pyrolysis of seaweed biomass (Ulva fasciata). It is proposed that the natural abundance of both inorganic and organic sulfur in the seaweed induces the reduction of exfoliated graphitic sheets at elevated temperatures. FeCl3 was employed both as the iron precursor as well as the templating agent. Iron doping played a dual-faceted role of exfoliating as well as activating agent, producing composite with high adsorption capacity for Pb2+ (645 ±â€¯10 mg/g), CR (970 mg/g), CV(909 mg/g), MO (664 mg/g), MB (402 mg/g) dyes and good recyclability (8 cycles). Pb2+ adsorption was irreversible even at low pH values and the spent composite (G-Fe-Pb) was utilized for efficient Cr(IV) removal (Ì´100 mg/g). The adsorption data followed the pseudo second order kinetics while the equilibrium data fitted perfectly into the Langmuir adsorption equation. Further, a thin layer of composite was deposited on a filter paper by vacuum filtration which was tested under continuous filtration mode for RB5 dye removal. Preliminary results highlight the potential of this composite to be used in pretreatment steps in hybrid membrane processes for filtration of complex wastewater feeds.


Asunto(s)
Compuestos Ferrosos/química , Grafito/química , Nanocompuestos/química , Ulva/química , Contaminantes Químicos del Agua/química , Purificación del Agua/métodos , Adsorción , Cromo/química , Colorantes/química , Plomo/química
18.
J Nanosci Nanotechnol ; 18(6): 3954-3959, 2018 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-29442731

RESUMEN

A simple new route for synthesis of fluorescent SnO2 and its application as an efficient sensing material for Fe3+ in aqueous media is reported. The fluorescent SnO2 nanoparticles were obtained by oxidation of SnCl2, which when used as reducing agent for the reduction of organic nitro compounds to corresponding amino compounds in ethanol. The SnO2 nanoparticles have been characterized on the basis of powder-XRD, IR, UV-Vis, TEM, FESEM and EDX analysis and found that this material is highly fluorescent in aqueous media. Detail study revealed that this material functions as a selective probe for Fe3+ out of a large number of metal ions used. The oxygen vacancies (defects) generated on the surface of the SnO2 during synthesis, are the source of emission due to recombination of electrons with the photo-excited hole in the valance bond. The quenching of emission intensity in presence of Fe3+ is due to the nonradiative recombination of electrons and holes at the surface. This material is used for estimation of Fe3+ in real samples such as drinking water, tap water and soil.

19.
ACS Appl Mater Interfaces ; 9(20): 17359-17368, 2017 May 24.
Artículo en Inglés | MEDLINE | ID: mdl-28470061

RESUMEN

A sunlight induced simple green route has been developed for the synthesis of polyacrylate functionalized gold nanoparticles (PAA-AuNPs), in which poly(acrylic acid) functions as a reducing as well as stabilizing agent. This material has been characterized on the basis of spectroscopic and microscopic studies; it exhibited selective colorimetric detection of Al3+ in aqueous media, and the Al3+ induced aggregated PAA-AuNPs exhibited detection of F- with sharp color change and high selectivity and sensitivity out of a large number of metal ions and anions tested. The mechanistic study revealed that, for Al3+, the color change is due to a shift of the SPR band because of the Al3+ induced aggregation of PAA-AuNPs, whereas for F-, the reverse color change (blue to red) with return of the SPR band to its original position is due to dispersion of aggregated PAA-AuNPs, as F- removes Al3+ from the aggregated species by complex formation. Only concentration-dependent fluoride ion can prevent Al3+ from aggregating PAA-AuNPs. The method is successfully used for the detection of F- in water collected from various sources by the spiking method, in toothpastes of different brands by the direct method. The solid Al3+-PAA-AuNPs were isolated, adsorbed on ZIF@8 (zeolitic imidazolate framework) and on a cotton strip, and applied as solid sensing material for detection of F- in aqueous media.

20.
ACS Appl Mater Interfaces ; 8(31): 20243-50, 2016 Aug 10.
Artículo en Inglés | MEDLINE | ID: mdl-27415029

RESUMEN

In this paper we correlate the solar cell performance with bimolecular packing of donor:acceptor bulk heterojunction (BHJ) organic solar cells (OSCs), where interchain ordering of the donor molecule and its influence on morphology, optical properties, and charge carrier dynamics of BHJ solar cells are studied in detail. Solar cells that are fabricated using more ordered defect free 100% regioregular poly(3-hexylthiophene) (DF-P3HT) as the donor polymer show ca. 10% increase in the average power conversion efficiency (PCE) when compared to that of the solar cell fabricated using 92% regioregularity P3HT, referred to as rr-P3HT. EQE and UV-vis absorption spectrum show a clear increase in the 607 nm vibronic shoulder of the DF-P3HT blend suggesting better interchain ordering which was also reflected in the less Urbach energy (Eu) value for this system. The increase in ordering inside the blend has enhanced the hole-mobility which is calculated from the single carrier device J-V characteristics. Electroluminance (EL) studies on the DF-P3HT system showed a red-shifted peak when compared to rr-P3HT-based devices suggesting low CT energy states in DF-P3HT. The morphologies of the blend films are studied using AFM and grazing-incidence wide-angle X-ray scattering (GIWAXS) suggesting increase in the roughness and phase segregation which could enhance the internal scattering of the light inside the device and improvement in the crystallinity along alkyl and π-stacking direction. Hence, higher PCE, lower Eu, red-shifted EL emission, high hole-mobility, and better crystallinity suggest improved interchain ordering has facilitated a more delocalized HOMO state in DF-P3HT-based BHJ solar cells.

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