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1.
PLoS One ; 19(5): e0299778, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38691573

RESUMO

Today, supply chain (SC) networks are facing more disruptions compared to the past. While disruptions are rare, they can have catastrophic long-term economic or societal repercussions, and the recovery processes can be lengthy. These can tremendously affect the SC and make it vulnerable, as observed during the COVID-19 pandemic. The identification of these concerns has prompted the demand for improved disruption management by developing resilient, agile, and adaptive SC. The aim of this study is to introduce an assessment framework for prioritizing and evaluating the determinants to supply chain resilience (SCR). To analyze the empirical data, fuzzy criteria importance through intercriteria correlation (fuzzy CRITIC) and fuzzy technique for order of preference by similarity to ideal solution (fuzzy TOPSIS) have been incorporated. Fuzzy CRITIC method was used to identify the critical determinants and fuzzy TOPSIS method was applied for determining relative ranking of some real-world companies. Finally, by developing propositions an interpretive triple helix framework was proposed to achieve SCR. This research stands out for its originality in both methodology and implications. By introducing the novel combination of Fuzzy CRITIC and Fuzzy TOPSIS in the assessment of determinants to SCR and applying these determinants with the help of interpretive triple helix framework to establish a resilient SC, this study offers a unique and valuable contribution to the field of SCR. The key findings suggest that 'Responsiveness' followed by 'Managerial coordination and information integration' are the most significant determinant to achieve SCR. The outcome of this work can assist the managers to achieve SCR with improved agility and adaptivity.


Assuntos
COVID-19 , Lógica Fuzzy , Pandemias , COVID-19/epidemiologia , Humanos , SARS-CoV-2
2.
Waste Manag Res ; : 734242X231197367, 2023 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-37728112

RESUMO

Waste management in the textile and clothing (TAC) industry is a challenging issue due to high resource consumption and pollution generation. Therefore, the adoption of industrial symbiosis (IS) is the need of the hour for the TAC industry. However, the adoption of IS in emerging economies like India, Brazil, Bangladesh, etc. is limited due to various impediments. The present work aims to identify and analyse these barriers and develop mitigation strategies in the context of Indian TAC industry. Eighteen IS barriers have been identified and validated; and the interrelationships among them are studied by applying the 'weighted influence non-linear gauge system (WINGS)' method, which not only estimates the intensity of influence but also takes the self-strength of barriers into account. The results show that lack of trust amongst supply chain partners, lack of financial incentives from the government, lack of guidance from regularity bodies and industry associations and lack of consumer awareness are the most significant barriers. Additionally, the strategies to mitigate these barriers are developed based on a quadruple helix framework considering academia--government-industry-society as the main actors. The findings of the study will be helpful for the TAC industry, policymakers and other concerned stakeholders in framing suitable strategies to improve the long-term waste management practices of the industry and to achieve sustainable development goals (SDGs).

3.
Int J Biol Macromol ; 252: 126457, 2023 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-37611684

RESUMO

In this work, the PVA-chitosan composite packaging films doped with biomass-fabricated zinc oxide nanoparticles (ZnO NPs) and dragon fruit waste extract (DFE) were developed for potential use in food packaging applications. ZnO NPs were synthesized using a sustainable method employing C. sinensis waste extract as a reducing agent. Chitosan and PVA were blended in a specific ratio (1: 1 w/w) to obtain a film-forming solution, into which the ZnO NPs and dragon fruit waste extract were incorporated. The resulting solution was cast into films, which were characterized using various analytical techniques. Mechanical properties, water solubility, and thermal stability of the films were also evaluated. The results demonstrated that the incorporation of green ZnO NPs and dragon fruit waste extract enhanced the mechanical strength and thermal stability of the films while reducing water vapor permeability. Moreover, the films exhibited biocidal and excellent 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging properties, indicating their use in the food packaging sector. The production of these films offers a practical approach to produce bioactive food packaging materials. The use of plant extract and waste material as reducing agents can reduce the overall cost of production while providing added benefits, such as antioxidant and antibacterial properties.


Assuntos
Quitosana , Nanopartículas , Óxido de Zinco , Quitosana/química , Embalagem de Alimentos/métodos , Óxido de Zinco/química , Frutas , Nanopartículas/química , Extratos Vegetais , Antibacterianos/farmacologia , Antibacterianos/química
4.
J Chem Phys ; 158(8): 084307, 2023 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-36859097

RESUMO

The ion impact multiple ionization and subsequent dissociation of CCl4 is studied using a beam of Ar7+ ion having the energy of about 1 MeV in a linear time- of-flight mass spectrometer, coupled with a position-sensitive detector. The complete, as well as incomplete Coulomb explosion pathways, for CCl4 2+ and CCl4 3+ ions are identified and studied. The kinetic energy release distributions of channels, kinetic energies, and momentum distributions of fragmented ions, as well as neutrals, are also calculated. Possible modes of fragmentation pathways, i.e., concerted and/or sequential, for all the identified channels are studied using Newton diagrams, Dalitz plots, and kinetic energy distributions. The dynamical information and fragmentation pathways were analyzed with the Dalitz plot and Newton diagram for the three-body dissociation channel. The nature of the fragmentation process is further investigated with simulated Dalitz plots and Newton diagrams using the simple classical mechanical model.

5.
Appl Phys A Mater Sci Process ; 128(10): 866, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36101661

RESUMO

In this work, a shock-free argon-fed plasma plume was generated by a variable-frequency power supply and the discharge characteristics were investigated from the voltage and current waveforms between 72 and 92 kHz frequencies. The higher electron temperature dominates the plasma chemical process and the average plasma temperature is about 30 â„ƒ under these conditions. The influence of non-thermal atmospheric plasma plume length and plume temperature on Ar gas flow is optimized at 7 sL/min. The average charge accumulation on the plume tip area and the dependence of flow rate on the plasma irradiation area were also explored. This atmospheric pressure plasma jet (APPJ) has been proposed for human-skin irradiation on different areas (even on the tongue) owing to its less painful, tingling and burning effect. Optical emission spectroscopy (OES) confirmed the presence of excited argon with reactive nitrogen (RNS) and oxygen species (ROS). This study contributes to a better understanding of non-thermal plasma effects on the human body which may find prospects for disinfection and prevention of different diseases during the current pandemic time. Supplementary Information: The online version contains supplementary material available at 10.1007/s00339-022-06022-w.

6.
Risk Anal ; 42(1): 85-96, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-34424559

RESUMO

The preparedness of Indian states and union territories (UTs) against the COVID-19 pandemic has been evaluated. Ten parameters related to demographic, socioeconomic, and healthcare aspects have been considered and the performances of 27 states and three UTs have been evaluated applying the Fuzzy Analytic Hierarchy Process. Opinions of medical experts have been considered to ascertain the relative importance of decision criteria as well as subcriteria. The scores of various states and UTs in each of the decision subcriteria have been calculated by using the secondary data collected from authentic sources. It is found that Kerala and Bihar are the best prepared and worst prepared states, respectively, to combat COVID-19 pandemic. Karnataka, Goa, and Tamil Nadu have very good preparedness whereas Chhattisgarh, Jharkhand, and Bihar have very poor preparedness. Maharashtra, the most affected state in India, has average preparedness. As around 650 million people are vulnerable due to the poor and very poor preparedness of their states, the country needs to make region specific mitigation strategies to combat the COVID-19 pandemic and the preparedness map will be helpful in that direction.


Assuntos
COVID-19/epidemiologia , Tomada de Decisões , Pandemias/prevenção & controle , Medição de Risco/métodos , SARS-CoV-2 , Humanos , Índia/epidemiologia
7.
J Ind Text ; 51(3 Suppl): 3613S-3647S, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38603152

RESUMO

The outbreak of COVID-19 has created renewed attention on research and large scale manufacturing of face masks. In the last two decades, usage of face masks for respiratory protection has gained increased importance as a measure to control the maladies and fatalities due to exposure to particulate pollutants and toxic pathogens. Numerous variants of surgical and high-performance respirator masks are available in the market, and yet the fibrous materials science researchers, manufacturers and public health agencies are making concerted efforts towards improvising them with respect to self-sterilisability, facial fit, thermo-physiological comfort, reusability and biodegradability, while maintaining or rather enhancing the filtration efficiency. This review article presents a compendium of materials, design and performance standards of existing face masks, as well as elaborates on developments made for their performance enhancement. The criticality of inculcation of good hygiene habits and earnest compliance to correct mask donning and doffing practices has also been highlighted. This review is expected to make valuable contributions in the present COVID-19 scenario when donning a face mask has become mandatory.

8.
Sustain Prod Consum ; 28: 543-555, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34722848

RESUMO

Recent outbreak of COVID-19 pandemic has provided strong impetus to supply chain resilience research. In a volatile and uncertain business environment, resilience can be incorporated by developing and implementing effective risk mitigation strategies. In this research, risk mitigation strategies for environmentally sustainable clothing supply chain have been prioritised by considering their efficacy to mitigate various risks. Twelve risks and thirteen mitigation strategies, identified through literature review and experts' opinion, are considered as decision criteria and alternatives respectively. Fuzzy Technique for Order Preference by Similarity to Ideal Solutions (fuzzy TOPSIS) is implemented under a group decision making scenario for prioritising the strategies. Developing supply chain agility; multiple green sourcing and flexible capacities; adoption of green practices; building trust, coordination and collaboration; and alignment of economic incentives and revenue sharing are found to be dominant risk mitigation strategies for environmentally sustainable clothing supply chain. These strategies have been viewed through the lens of resource dependence, change management and transaction cost theories. Organisation desirous to build resilience in their supply chain can prioritise the risk mitigation strategies and adopt a portfolio of strategies based on the outcome of this research.

9.
Materials (Basel) ; 14(12)2021 Jun 09.
Artigo em Inglês | MEDLINE | ID: mdl-34207839

RESUMO

We report the surface stoichiometry of Tix-CuyNz thin film as a function of film depth. Films are deposited by high power impulse (HiPIMS) and DC magnetron sputtering (DCMS). The composition of Ti, Cu, and N in the deposited film is investigated by X-ray photoelectron spectroscopy (XPS). At a larger depth, the relative composition of Cu and Ti in the film is increased compared to the surface. The amount of adventitious carbon which is present on the film surface strongly decreases with film depth. Deposited films also contain a significant amount of oxygen whose origin is not fully clear. Grazing incidence X-ray diffraction (GIXD) shows a Cu3N phase on the surface, while transmission electron microscopy (TEM) indicates a polycrystalline structure and the presence of a Ti3CuN phase.

10.
Int J Biol Macromol ; 181: 1092-1103, 2021 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-33892039

RESUMO

This study explores the effect of plasticisers (lotader AX8900, polyethylene glycol and triethyl citrate) on biodegradability of polylactic acid (PLA) and its composites with halloysite nanotubes and ramie fabric by soil burial method. Changes in surface morphology and mechanical properties were evaluated to quantify the degradation behaviour of all samples. The results showed that the relative loss in tensile strength of ramie-PLA composites was more than that of neat PLA or plasticised PLA films. Also, ramie-PLA composite, where ramie fabric was treated with diammonium orthophosphate, had degraded entirely after 60 days of soil burial. It was also confirmed by Fourier transform infrared spectroscopy that the chemical structures of neat PLA and plasticised PLA films changed after the soil burial test. The use of these additives not only reduces the brittleness of PLA but also accelerates the biodegradation rate of PLA. Thus, PLA, along with additives, can help in reduction of carbon footprint and other environmental issues customarily associated with petro based polymers. Therefore, the finding supports the notion of PLA usage as a viable alternative to fossil fuel-based materials.


Assuntos
Biodegradação Ambiental , Boehmeria/química , Nanotubos/química , Solo/química , Citratos/química , Ácido Láctico/química , Plastificantes/química , Plastificantes/toxicidade , Poliésteres/química , Polietilenoglicóis/química , Polímeros/química , Resistência à Tração/efeitos dos fármacos , Água/química
11.
ACS Omega ; 5(49): 31918-31924, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-33344846

RESUMO

A comprehensive study on the electronic structure and optical properties of a Cu3N film is performed by the first-principles study using density functional theory. The Hubbard (U) term is added in the local density approximation approach for improvement of the theoretical band gap energy. The band structure of the Cu3N unit cell shows a strong hybridization of Cu 3d and N 2p orbitals in the near-valence band region (M) because of their antibonding states which are also observed by molecular orbitals (HOMO-LUMO). The conduction band is dominated by a very small amount of Cu 3p and N 2p orbitals. The density of states exhibits a negligible deformation in Cu-N bonding. The Cu3N thin film deposited by the DC magnetron-sputtering technique shows a polycrystalline structure with a nonstoichiometric Cu3N phase. The experimentally obtained optical band gap and refractive index of the Cu3N film are 1.44 eV and 2.14, respectively, which are comparable with those from the theoretical approximation.

12.
Sustain Prod Consum ; 24: 150-155, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37273277

RESUMO

The recent outbreak of the coronavirus disease (COVID-19) has exposed the fragility of the clothing supply chain operating in South Asian countries. Millions of workers have become jobless and are staring at an uncertain future. The purpose of this research is to understand the reasons behind the lack of social sustainability in the clothing supply chain operating in South Asian countries and to suggest ways for an appropriate redressal. Interviews with experts have revealed that the dominant power of some brands in the clothing supply chain is the primary reason. Unauthorised subcontracting of clothing manufacturing and the use of contract labour are also responsible for violations in the 'code of conducts' of social compliance. Post COVID-19, a sustainable sourcing model that incorporates disruption risk sharing contracts between the brands and suppliers should be adopted. Unauthorised subcontracting of clothing manufacturing by the suppliers must be prohibited. Supplier selection and the order allocation policies of the brands should also be tuned to facilitate social security of workers. The participation of NGOs and labour unions should be encouraged so that community development initiatives reach the grassroots level.

13.
Int J Biol Macromol ; 153: 1165-1175, 2020 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-31756463

RESUMO

The properties of PLA films intended for packaging applications have been modulated by using bio-based platicizers and naturally obtained fillers. Triethyl citrate (TEC) and glycerol triacetate (GTA) have been used as platicizers and halloysite nanotubes (HNT) and chitosan have been used as fillers. The addition of 10 wt% TEC, 10 wt% GTA and 3 wt% HNT improves the ductility of PLA films, however, reduces the tensile modulus and tensile strength. Addition of chitosan (1 wt%), on the other hand, acts as a good reinforcing filler and improves the tensile strength and tensile modulus. PLA-HNT-chitosan film show comparable tensile strength, tensile modulus and ~12 times higher elongation at break compared to pure PLA. Besides, PLA-HNT-chitosan film demonstrates very good barrier properties against moisture and ultraviolet (UV) rays. Additionally, its antibacterial efficacy against E. coli and S. aureus are found to be around 80% and 70%, respectively. The study demonstrates the complementary effects of HNT and chitosan to modulate the properties of PLA film and indicates that the PLA-HNT-chitosan film can emerge as a very potent material for packaging applications.


Assuntos
Embalagem de Alimentos/métodos , Plastificantes/química , Poliésteres/química , Poliésteres/farmacologia , Antibacterianos/química , Antibacterianos/farmacologia , Fenômenos Mecânicos , Fenômenos Ópticos , Permeabilidade , Vapor , Temperatura
14.
Mater Sci Eng C Mater Biol Appl ; 54: 26-31, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26046264

RESUMO

The development and performance optimization of knitted antibacterial materials made from polyester-silver nanocomposite fibres have been attempted in this research. Inherently antibacterial polyester-silver nanocomposite fibres were blended with normal polyester fibres in different weight proportions to prepare yarns. Three parameters, namely blend percentage (wt.%) of nanocomposite fibres, yarn count and knitting machine gauge were varied for producing a large number of knitted samples. The knitted materials were tested for antibacterial activity against Gram-positive bacteria Staphylococcus aureus. Statistical analysis revealed that all the three parameters were significant and the blend percentage of nanocomposite fibre was the most dominant factor influencing the antibacterial activity of knitted materials. The antibacterial activity of the developed materials was found to be extremely durable as there was only about 1% loss even after 25 washes. Linear programming approach was used to optimize the parameters, namely antibacterial activity, air permeability and areal density of knitted materials considering cost minimization as the objective. The properties of validation samples were found to be very close to the targeted values.


Assuntos
Antibacterianos/química , Nanopartículas Metálicas/química , Nanocompostos/química , Prata/química , Modelos Lineares , Poliésteres/química , Staphylococcus aureus/efeitos dos fármacos
15.
Rev Sci Instrum ; 85(2): 025107, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24593396

RESUMO

We report the design and development of a simple, electrically low powered and fast heating versatile electron beam annealing setup (up to 1000 °C) working with ultra high vacuum (UHV) chamber for annealing thin films and multilayer structures. The important features of the system are constant temperature control in UHV conditions for the temperature range from room temperature to 1000 ºC with sufficient power of 330 W, at constant vacuum during annealing treatment. It takes approximately 6 min to reach 1000 °C from room temperature (∼10(-6) mbar) and 45 min to cool down without any extra cooling. The annealing setup consists of a UHV chamber, sample holder, heating arrangement mounted on suitable UHV electrical feed-through and electronic control and feedback systems to control the temperature within ±1 ºC of set value. The outside of the vacuum chamber is cooled by cold air of 20 °C of air conditioning machine used for the laboratory, so that chamber temperature does not go beyond 50 °C when target temperature is maximum. The probability of surface oxidation or surface contamination during annealing is examined by means of x-ray photoelectron spectroscopy of virgin Cu sample annealed at 1000 °C.

16.
Photodermatol Photoimmunol Photomed ; 29(4): 182-9, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23815350

RESUMO

INTRODUCTION: Ultraviolet protection factor (UPF) of fabric is mainly influenced by fabric cover which is dependent on the primary fabric construction parameters like yarn count and thread density. UPF can be modeled by using these primary fabric parameters as inputs by the help of nonlinear regression as well as artificial neural network (ANN). OBJECTIVES: The objective of this study is to develop prediction models for fabric UPF using nonlinear regression and ANN techniques and compare their relative efficacy. METHODS: Thirty-six woven fabric samples were produced by varying weft related parameters like proportion of polyester, weft count and pick density. Nonlinear regression and ANN models were developed from same experimental data sets. Prediction accuracy of both the models was evaluated and compared. Trend analysis was performed to check the generalization ability of the ANN model. RESULTS: UPF was well estimated from the three primary fabric parameters by both the nonlinear regression and ANN models. However, ANN model demonstrated better prediction accuracy than the nonlinear regression model. CONCLUSIONS: Fabric UPF can be predicted with high degree of accuracy using ANN and nonlinear regression models. These models can be used to estimate the UPF of woven fabrics without spectrophotometer based test.


Assuntos
Fibra de Algodão , Redes Neurais de Computação , Poliésteres , Raios Ultravioleta/efeitos adversos
17.
J Dtsch Dermatol Ges ; 10(7): 509-15, 2012 Jul.
Artigo em Inglês, Alemão | MEDLINE | ID: mdl-22405534

RESUMO

BACKGROUND: Cold plasma, a new treatment principle in dermatology based on ionic discharge delivering reactive molecular species and UV-light, exhibits strong antimicrobial efficacy in vitro and in vivo. Before implementing plasma as new medical treatment tool, its safety must be proven, as well as assessing skin tolerance and patient acceptance. PATIENTS AND METHODS: We investigated the plasma effects of three different plasma sources (pulsed, non-pulsed atmospheric pressure plasma jet (APPJ) and a dielectric barrier discharge (DBD)) on the transepidermal water loss (TEWL) and skin moisture after treating the fingertips of four healthy male volunteers. RESULTS: TEWL values were reduced by pulsed APPJ and DBD by about 20% but increased after non-pulsed APPJ by 5-20%. TEWL values normalized 30 min after all forms of plasma treatment. Skin moisture was increased immediately and 30 min after treatment with pulsed APPJ but was not affected by non-pulsed APPJ and DBD. CONCLUSIONS: All plasma treatments were well-tolerated and did not damage the skin barrier nor cause skin dryness. Cold plasma fulfils basic recommendations for safe use on human skin and as future option may serve as the first physical skin antiseptic.


Assuntos
Água Corporal/efeitos dos fármacos , Gases em Plasma/farmacologia , Absorção Cutânea/efeitos dos fármacos , Absorção Cutânea/fisiologia , Perda Insensível de Água/efeitos dos fármacos , Perda Insensível de Água/fisiologia , Adulto , Humanos , Masculino , Gases em Plasma/efeitos adversos
18.
Photodermatol Photoimmunol Photomed ; 28(2): 58-67, 2012 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-22409708

RESUMO

INTRODUCTION: The weave, fabric cover, areal density and ultraviolet (UV) absorbers are some of the factors which influence the ultraviolet protection factor (UPF) of cotton fabrics. It will be of interest to know whether fabric cover or fabric areal density is a better predictor of cotton fabric UPF. It will also be of interest to know whether the UV absorbers are equally effective for all kinds of cotton fabric. OBJECTIVES: To understand the role of weave, fabric cover, areal density and UV absorbers on the UPF of cotton fabrics. To establish quantitative relationships between the fabric cover, areal density and UPF for cotton fabrics. METHODS: Sixty-four woven fabrics were manufactured using different weaves, cotton yarn count and picks per centimetre values. Nonlinear regression models were developed to relate the fabric cover and areal density with the UPF. The role of UV absorbers at different levels of cover has been analysed. RESULTS: In case of bleached cotton fabrics woven with 40 Ne warp yarn count, 40 ends per cm, different weft yarn count (20-40 Ne) and picks per centimetre (15-27), weave does not have a statistically significant effect on the UPF. Fabric areal density is a better predictor of UPF than the fabric cover. The UV absorbers are more effective when the fabric cover is high. CONCLUSIONS: The developed equations relating fabric cover and UPF can be used as a primary guideline while selecting fabrics for UV protection.


Assuntos
Fibra de Algodão , Raios Ultravioleta , Técnicas In Vitro , Luz Solar
19.
Photodermatol Photoimmunol Photomed ; 26(6): 290-6, 2010 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-21091786

RESUMO

INTRODUCTION: Cotton fabrics used in summer do not often provide good protection against solar ultraviolet (UV) radiation. Heavy cotton fabrics can provide good protection against UV radiation. However, heavy fabrics are not good from a comfort point of view as the air permeability and moisture vapour transmission rate is very low. OBJECTIVES: To engineer cotton fabrics which will provide maximum UV protection without sacrificing the minimum requirement of air permeability and thermal resistance for a particular climatic condition. METHODS: Sixteen plain and sixteen twill woven fabrics were manufactured using different cotton yarn count and picks per cm. Nonlinear regression models were developed to relate the fabric parameters with the ultraviolet protection factor (UPF), air permeability and thermal resistance. Optimization problems were formulated for UPF maximization keeping air permeability and thermal resistance as constraints. Optimization problems were solved to find out the values of yarn count and picks per cm. New fabrics were then woven using optimized combinations of yarn count and picks per cm, and error assessment between the target and the achieved fabric properties was performed. RESULTS: The target, optimized and achieved fabric properties are showing good association. When air permeability requirement is high, the engineered cotton fabric can provide good UV protection (UPF > 15). When the air permeability requirement is low, the engineered cotton fabric can provide excellent UV protection (UPF > 40). CONCLUSIONS: It is possible to engineer cotton fabrics to maximize the UV protection without compromising with the comfort properties.


Assuntos
Fibra de Algodão , Proteção Radiológica , Protetores Solares , Raios Ultravioleta , Humanos , Permeabilidade
20.
J Phys Chem B ; 113(48): 15734-41, 2009 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-19894689

RESUMO

We have studied the influence of nitrogen on the chemical properties of the hydrogenated carbon nitride (a-CN(x):H) film deposited by CH(4)/N(2) dielectric barrier discharge (DBD) plasma. X-ray photoelectron spectroscopy (XPS) indicates that carbon and nitrogen form an unpolarized covalent bond in these C-N(x) materials, and the observed chemical shift in the C 1s and N 1s binding energy is explained with respect to N 1s incorporation. Furthermore, the average nitrogen content (N/C approximately 0.76) in the films was systematically varied by changing the nitrogen partial pressure (CH(4)/N(2) approximately from 5:1 to 1:7) which is well supported by the elemental analysis. Fourier transform infrared (FTIR) absorption spectra exhibit significant changes in different C-N, C identical withN, and NH/OH molecular bands at higher nitrogen concentration in the film. The isonitrile and nitrile groups (-NC and -CN) are increased with the increase of deposition time. In addition, the elemental analysis, proton NMR, and thermolysis mass spectrum show that the composition of the film with the ratio CH(4)/N(2) approximately 1:1 is C, 67.68; H, 9.88; N, 16.53 (in wt %) and that the film is composed of polymers, probably containing linear chains which are cleaved off on heating in vacuum.


Assuntos
Membranas Artificiais , Metano/química , Nitrogênio/química , Eletricidade , Propriedades de Superfície
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