Showing papers by "Cochin University of Science and Technology published in 2014"
Tufts University1, University of Connecticut2, Remote Sensing Center3, Polish Academy of Sciences4, Peking University5, Gazprom6, Stockholm University7, Finnish Meteorological Institute8, Panjab University, Chandigarh9, University of Dundee10, University of California, Berkeley11, Nordland Research Institute12, Cochin University of Science and Technology13, Arctic and Antarctic Research Institute14
TL;DR: In this paper, the authors argue that optimism regarding the potential of the Arctic routes as an alternative to the Suez Canal is overstated and that the route involves many challenges: jurisdictional disputes create political uncertainties; shallow waters limit ship size; lack of modern deepwater ports and search and rescue capabilities requires ships to have higher standards of autonomy and safety; harsh weather conditions and free-float...
Abstract: The Russian and Norwegian Arctic are gaining notoriety as an alternative maritime route connecting the Atlantic and Pacific Oceans and as sources of natural resources. The renewed interest in the Northeast Passage or the Northern Sea Route is fueled by a recession of Arctic sea ice coupled with the discovery of new natural resources at a time when emerging and global markets are in growing demand for them. Driven by the expectation of potential future economic importance of the region, political interest and governance has been rapidly developing, mostly within the Arctic Council. However, this paper argues that optimism regarding the potential of Arctic routes as an alternative to the Suez Canal is overstated. The route involves many challenges: jurisdictional disputes create political uncertainties; shallow waters limit ship size; lack of modern deepwater ports and search and rescue (SAR) capabilities requires ships to have higher standards of autonomy and safety; harsh weather conditions and free-float...
229 citations
TL;DR: In cancer patients, 90 % of ARDS cases are infection-related, including one-third due to invasive fungal infections, and Mortality has decreased over time.
Abstract: Little attention has been given to ARDS in cancer patients, despite their high risk for pulmonary complications. We sought to describe outcomes in cancer patients with ARDS meeting the Berlin definition. Data from a cohort of patients admitted to 14 ICUs between 1990 and 2011 were used for a multivariable analysis of risk factors for hospital mortality. Of 1,004 included patients (86 % with hematological malignancies and 14 % with solid tumors), 444 (44.2 %) had neutropenia. Admission SOFA score was 12 (10–13). Etiological categories were primary infection-related ARDS (n = 662, 65.9 %; 385 bacterial infections, 213 invasive aspergillosis, 64 Pneumocystis pneumonia); extrapulmonary septic shock-related ARDS (n = 225, 22.4 %; 33 % candidemia); noninfectious ARDS (n = 76, 7.6 %); and undetermined cause (n = 41, 4.1 %). Of 387 (38.6 %) patients given noninvasive ventilation (NIV), 276 (71 %) subsequently required endotracheal ventilation. Hospital mortality was 64 % overall. According to the Berlin definition, 252 (25.1 %) patients had mild, 426 (42.4 %) moderate and 326 (32.5 %) severe ARDS; mortality was 59, 63 and 68.5 %, respectively (p = 0.06). Mortality dropped from 89 % in 1990–1995 to 52 % in 2006–2011 (p < 0.0001). Solid tumors, primary ARDS, and later admission period were associated with lower mortality. Risk factors for higher mortality were allogeneic bone-marrow transplantation, modified SOFA, NIV failure, severe ARDS, and invasive fungal infection. In cancer patients, 90 % of ARDS cases are infection-related, including one-third due to invasive fungal infections. Mortality has decreased over time. NIV failure is associated with increased mortality. The high mortality associated with invasive fungal infections warrants specific studies of early treatment strategies.
217 citations
TL;DR: A phase 3 trial and a cohort study found no association between gastrointestinal events and olmesartan, and the association has been questioned.
Abstract: BACKGROUND: Recently, a new enteropathy has been described: olmesartan-associated enteropathy. However, the association has been questioned: a phase 3 trial and a cohort study found no association between gastrointestinal events and olmesartan. AIM: To collect French cases of sartan-associated enteropathy to describe further this entity, confirm or refute causality, and determine if the association exists with other sartans. METHODS: French gastroenterologists were invited to report cases of sartan-associated enteropathy and collect clinical, biological and histological data. Patients with diarrhoea and histological duodenal abnormalities were included. RESULTS: Thirty-six patients with olmesartan-associated enteropathy were reported, including 32 with villous atrophy and four without. There was only one patient with irbesartan-associated enteropathy. None of the patients died. Patients with villous atrophy had diarrhoea, vomiting, renal failure, hypokalaemia, body weight loss and hypoalbuminaemia. Thirty-one patients were hospitalised; four required intensive care. Anti-transglutaminase and anti-enterocyte antibodies were negative; anti-nuclear antibodies were positive (9/11). Endoscopic duodenal biopsies showed villous atrophy (32/32) and polyclonal intra-epithelial CD3+CD8+ lymphocytosis (11/11). Exactly, 14/15 patients responded to steroids and/or immunosuppressants, prescribed because of suspected autoimmune enteropathy. Ten olmesartan interruptions were followed by reintroductions before steroids or immunosuppressants. Interruptions were followed by remissions (9/10), but reintroductions were followed by relapses (9/9). Twenty-nine patients were in remission since olmesartan interruption, including 26 without immunosuppressants. Patients with normal villi had similar clinical characteristics, but mild histological abnormalities (intra-epithelial lymphocytosis and lamina propria lymphocytic infiltration). CONCLUSIONS: Olmesartan causes a severe and immune-mediated enteropathy, with or without villous atrophy. Enteropathy associated with other sartans seems to be very rare.
155 citations
TL;DR: In this article, microwave exfoliated reduced graphene oxide (MERGO) was prepared from natural graphite for subsequent fabrication of epoxy nanocomposites using triethylenetetramine (TETA) as a curing agent via in-situ polymerization.
131 citations
TL;DR: This paper surveys work related to queues with interruptions that occur due to many reasons such as server breakdowns, servers taking emergency breaks, and customers having incomplete information or getting distracted.
Abstract: In this paper we survey work related to queues with interruptions that occur due to many reasons such as server breakdowns, servers taking emergency breaks, and customers having incomplete information or getting distracted We look at both continuous and discrete time queueing models with interruptions in this survey
129 citations
TL;DR: The presence of weight loss, arthralgia, skin lesions, and ANA was associated with the development of SLE, and male sex and lymphopenia were associated with severe forms of KFD (p < 0.05).
126 citations
TL;DR: Interest in psychological empowerment and employee engagement has increased substantially over the last decade among practitioners and academicians as mentioned in this paper, however they have emerged independent of each other independent from each other, and are not independent of any single organization.
Abstract: Interest in psychological empowerment and employee engagement has increased substantially over the last decade among practitioners and academicians. However they have emerged independent of each ot...
98 citations
TL;DR: The results indicate that luteolin protects BEAS-2B cells from Cr(VI)-induced carcinogenesis by scavenging ROS and modulating multiple cell signaling mechanisms that are linked to ROS.
82 citations
TL;DR: Guideline-concordant VKA reversal with PCC and vitamin K within eight hours after admission was associated with a significant decrease in seven-day mortality.
Abstract: Introduction: In vitamin K antagonist (VKA)-treated patients with severe hemorrhage, guidelines recommend prompt VKA reversal with prothrombin complex concentrate (PCC) and vitamin K. The aim of this observational cohort study was to evaluate the impact of guideline concordant administration of PCC and vitamin K on seven-day mortality. Methods: Data from consecutive patients treated with PCC were prospectively collected in 44 emergency departments. Type of hemorrhage, coagulation parameters, type of treatment and seven-day mortality mortality were recorded. Guideline-concordant administration of PCC and vitamin K (GC-PCC-K) were defined by at least 20 IU/kg factor IX equivalent PCC and at least 5 mg of vitamin K performed within a predefined time frame of eight hours after admission. Multivariate analysis was used to assess the effect of appropriate reversal on seven-day mortality in all patients and in those with intracranial hemorrhage (ICH). Results: Data from 822 VKA-treated patients with severe hemorrhage were collected over 14 months. Bleeding was gastrointestinal (32%), intracranial (32%), muscular (13%), and “other” (23%). In the whole cohort, seven-day mortality was 13% and 33% in patients with ICH. GC-PCC-K was performed in 38% of all patients and 44% of ICH patients. Multivariate analysis showed a two-fold decrease in seven-day mortality in patients with GC-PCC-K (odds ratio (OR) = 2.15 (1.20 to 3.88); P = 0.011); this mortality reduction was also observed when only ICH was considered (OR = 3.23 (1.53 to 6.79); P = 0.002). Conclusions: Guideline-concordant VKA reversal with PCC and vitamin K within eight hours after admission was associated with a significant decrease in seven-day mortality.
81 citations
TL;DR: Direct oral anticoagulants are approved for multiple thromboembolic disorders and provide advantages over existing agents and for life-threatening bleeding, use of nonspecific prohemostatic agents may be considered, although clinical evidence is scarce.
Abstract: Direct oral anticoagulants (DOACs) are approved for multiple thromboembolic disorders and provide advantages over existing agents. As with all anticoagulants, management protocols for the eventuality of bleeding are important. Randomized phase III studies generally show that DOACs have a similar risk of clinically relevant bleeding compared with standard anticoagulants, with reductions in major bleeding in some cases. This may be particularly important in patients with atrial fibrillation, for whom the rate of intracranial hemorrhage was approximately halved with DOACs compared with warfarin. Conversely, the risk of gastrointestinal bleeding may be increased. Specific patient characteristics, such as renal impairment, comedications, and particular aspects of each drug, including the proportion eliminated by the kidneys, must be taken into account when assessing the risk of bleeding. Although routine coagulation monitoring of DOACs is not required, it may be useful under some circumstances. Of the traditional clotting assays, a sensitive and calibrated prothrombin time may be useful for detecting the presence or absence of clinically relevant factor Xa inhibitor concentrations (rivaroxaban or apixaban), but specific anti-factor Xa assays can measure drug levels quantitatively. For dabigatran, the results of an activated partial thromboplastin time test may exclude a clinically relevant pharmacodynamic effect, but a calibrated dilute thrombin time assay can be used for quantification of drug levels. In the event of mild or moderate bleeding, normal hemostatic support measures are recommended. For life-threatening bleeding, use of nonspecific prohemostatic agents may be considered, although clinical evidence is scarce. Specific antidotes are in development.
81 citations
TL;DR: Evidence is offered that adjuvant immunotherapy that targets NK cells in M-LN for activation may improve treatment of patients with sentinel lymph node-positive melanoma.
Abstract: Melanomas are characterized by high metastatic potential, with regional lymph node representing the most frequent site of early dissemination in this disease. These regional lymph nodes also represent the primary site for differentiation of natural killer (NK) cells. Although blood-derived NK cells can efficiently lyse melanoma cells isolated from metastatic lymph node (M-LN), there has been no study of the properties of the most disease-relevant NK cells isolated from M-LN in patients with melanoma. Here, we report that M-LN contains 0.5% to 11% of CD56(bright) NK cells among CD45(+) hematopoietic cells present and that this cell population surrounds tumor cell clusters in M-LN. This NK cell population was characterized by expression of CD62L, chemokine receptors, and high levels of natural cytotoxicity receptors (NCR), NK group 2 D (NKG2D), and DNAX accessory molecule 1 (DNAM-1). Expression of NCR-NKp30 and NKG2D correlated negatively with percentages of tumor cells in M-LN. Interestingly, M-LN contained a unique subset of mature CD56(bright)CD16(+) NK cells displaying coregulated expression of NCR and NKG2D activating receptors. Ex vivo analyses suggested that M-LN-derived NK cells were inactive but could be activated by appropriate cytokine signals [interleukin (IL)-2 or IL-15], and could lyse metastatic melanoma cells in a highly efficient manner compared with blood-derived NK cells. Taken together, the results offer evidence that adjuvant immunotherapy that targets NK cells in M-LN for activation may improve treatment of patients with sentinel lymph node-positive melanoma.
TL;DR: In this article, the authors applied the state-of-the-art ADCIRC hydrodynamic model to evaluate peak surge and onshore inundation along coastal Tamil Nadu for the December 2011 Thane cyclone event.
TL;DR: In this article, a defected ground structure (DGS) for improving isolation between four ports in a collocated multiple-input-multiple-output (MIMO) antenna is proposed.
Abstract: A defected ground structure (DGS) for improving isolation between four ports in a collocated multiple-input–multiple-output (MIMO) antenna is proposed. Isolation improvement by 7 dB is achieved by reducing surface waves within the dielectric substrate. Mutual coupling values as low as −25 dB are obtained along both the E- and H-planes. The MIMO antenna includes a square patch antenna surrounded by a square ring patch antenna with the DGS etched in the form of a square ring. The DGS effectively suppresses the cross-polarisation levels for all radiating modes. The design and effectiveness of the DGS in improving isolation for a fabricated 4-port antenna are discussed.
TL;DR: In this paper, a cost effective and efficient method for the preparation of fuel grade biodiesel by the transesterification of jatropha oil at room temperature over a coconut husk derived catalyst under mild reaction conditions without the use of any cosolvent is reported.
TL;DR: In this article, a chipless RFID tag using a stepped impedance resonator (SIR) is proposed, which utilizes both the fundamental and first harmonic frequency of the SIR to represent two bit information with a single resonator.
Abstract: A novel compact multiple-bit encoded chipless RFID tag using a stepped impedance resonator (SIR) is proposed. The main advantage of SIR compared with other resonators is the independent control over the fundamental as well as first harmonic frequency by varying either the impedance ratio (K) or length ratio (α). The tag utilizes both the fundamental and the first harmonic frequency of the SIR to represent two bit information with a single resonator. The tag is capable of representing 2
2N
number of bit combinations with N resonators. RFID tags are fabricated on C-MET LK4.3 (e
r
= 4.3 and tanδ = 0.0018) and RT Duriod (e
r
= 2.2 and tanδ = 0.0009) substrates. The structural information of the tag is encoded in the frequency spectrum, both in the magnitude and group delay of the backscattered signal. The data encoding capacity of the tag is enhanced by using the frequency shift coding technique. The proposed RFID tags have an operating range of 50 cm in the outdoor environment. Theoretical and numerical methods are used to verify the measured resonant frequencies of the tag.
TL;DR: In CA patients treated with cooling, stenting for AMI is associated with a high risk of stent thrombosis, and a strategy aiming to reduce this complication may probably improve prognosis of patients who underwent coronary sudden death.
TL;DR: In this article, the optical band gap of the Cu2O and CuO was 2.31 and 1.41 eV, respectively, and the bottom gate structured transparent TFTs fabricated using p-type CuO active layers operated in enhancement mode with an on/off ratio of 104 and field effect mobility of 0.01 cm2/V
31 Oct 2014
TL;DR: A polymer blend is a mixture of two or more polymers that have been blended together to create a new material with different physical properties as discussed by the authors, where the properties of the blends can be manipulated according to their end use by correct selection of the component polymers.
Abstract: A polymer blend is a mixture of two or more polymers that have been blended together to create a new material with different physical properties. Generally, there are five main types of polymer blend: thermoplastic–thermoplastic blends; thermoplastic–rubber blends; thermoplastic–thermosetting blends; rubber– thermosetting blends; and polymer–filler blends, all of which have been extensively studied. Polymer blending has attracted much attention as an easy and cost-effective method of developing polymeric materials that have versatility for commercial applications. In other words, the properties of the blends can be manipulated according to their end use by correct selection of the component polymers [1]. Today, the market pressure is so high that producers of plastics need to provide better and more economic materials with superior combinations of properties as a replacement for the traditional metals and polymers. Although, plastic raw materials are more costly than metals in terms of weight, they are more economical in terms of the product cost. Moreover, polymers are corrosion-resistant, possess a light weight with good toughness (which is important for good fuel economy in automobiles and aerospace applications), and are used for creating a wide range of goods that include household plastic products, automotive interior and exterior components, biomedical devices, and aerospace applications [2]. The development and commercialization of new polymer usually requires many years and is also extremely costly. However, by employing a polymer blending process – which is also very cheap to operate – it is often possible to reduce the time to commercialization to perhaps two to three years [2]. As part of the replacement of traditional polymers, the production of polymer blends represents half of all plastics produced in 2010. Today, the polymer industry is becoming increasingly sophisticated, with ultra-high-performance injection molding machines and extruders available that allow phase-separations and viscosity changes to be effectively detected or manipulated during the processing stages [3]. Whilst this modern blending technology can also greatly extend the performance capabilities of 1
TL;DR: The results indicate that dysnatremia correction is independently associated with survival, with the effect being greater with faster correction rates of up to 12 mmol/L per day.
Abstract: Increasing evidence suggests that dysnatremia at intensive care unit (ICU) admission may predict mortality. Little information is available, however, on the potential effect of dysnatremia correction. This is an observational multicenter cohort study in patients admitted between 2005 and 2012 to 18 French ICUs. Hyponatremia and hypernatremia were defined as serum sodium concentration less than 135 and more than 145 mmol/L, respectively. We assessed the influence on day 28 mortality of dysnatremia correction by day 3 and of the dysnatremia correction rate. Of 7,067 included patients, 1,830 (25.9%) had hyponatremia and 634 (9.0%) had hypernatremia at ICU admission (day 1). By day 3, hyponatremia had been corrected in 1,019 (1,019/1,830; 55.7%) and hypernatremia in 393 (393/634; 62.0%) patients. After adjustment for confounders, persistent hyponatremia or hypernatremia on day 3 was independently associated with higher day 28 mortality (odds ratio [OR], 1.31; 95% confidence interval [95% CI], 1.06 - 1.61; and OR, 1.86; 95% CI, 1.37 - 2.54; respectively). Hyponatremia corrected by day 3, hypernatremia corrected by day 3, and ICU-acquired hyponatremia were not associated with day 28 mortality. Median correction rate from days 1 to 3 was 2.58 mmol/L per day (interquartile range, 0.67 - 4.55). Higher natremia correction rate was associated with lower crude and adjusted day 28 mortality rates (OR per mmol/L per day, 0.97; 95% CI, 0.94 - 1.00; P = 0.04; and OR per mmol/L per day, 0.93; 95% CI, 0.90 - 0.97; P = 0.0003, respectively). Our results indicate that dysnatremia correction is independently associated with survival, with the effect being greater with faster correction rates of up to 12 mmol/L per day.
TL;DR: The observed relationship between high blood glucose level and outcome after cardiac arrest suggests the need to test a strategy combining both control of glycemia and minimization of glycemic variations for its ability to improve post-resuscitation care.
Abstract: Introduction
The influence of blood glucose (BG) level during the post-resuscitation period after out-of-hospital cardiac arrest (OHCA) is still debated. To evaluate the relationship between blood glucose level and outcome, we included the median glycemia and its maximal amplitude over the first 48 h following ICU admission in an analysis of outcome predictors.
TL;DR: Total organic carbon (TOC) and dissolved organic matter (DOM) play important roles in controlling the mercury sequestration process by the sediments from the central east coast of India, however, high concentrations of DOM in water column may increase Hg sequestration by sediments.
23 Apr 2014
TL;DR: In this article, the authors present challenges and issues in smart grid concept with solutions, and present solutions to the problems of the smart grid, which is to promote clean energy, control the energy consumption pattern and bring security to grid.
Abstract: Great efforts are being made all over the world towards the promotion of clean energy for environmental protection and scheduling energy consumption pattern to meet its increasing demand. The grid is to be modified or upgraded to promote clean energy, control the energy consumption pattern and bring security to grid. The smart grid will fulfil these requirements. The developments in information and communication technology support the smart grid vision. Sensor and control technologies also support the up-gradation of existing grid to smart grid. There are many challenges and issues in the implementation of smart grid. This paper presents challenges and issues in smart grid concept with solutions.
TL;DR: Conservative treatment or detorsion without oophorectomy is recommended for pre-menopausal women regardless of the estimated torsion duration and macroscopic appearance of the ovary.
01 Jan 2014
TL;DR: The properties of bio-composites are influenced by a number of factors such as fiber type, environmental conditions of preparation, processing method, as well as any modifications to the fiber via physical or chemical means as discussed by the authors.
Abstract: Bio-composites are prepared using natural fibers for the reinforcement phase and natural rubber or other natural polymer for the matrix. Natural fibers are abundantly available and cheap, and many have high strength and stiffness, as well as low cost and density. The properties of bio-composites are influenced by a number of factors such as fiber type, environmental conditions of preparation, processing method, as well as any modifications to the fiber via physical or chemical means. Various production techniques such as extrusion, calendaring, compression molding, injection molding, etc., may be employed in the manufacture of composite products.
TL;DR: Investigation on the ZnO mediated sono, photo and sonophoto catalytic degradation of phenol pollutant in water reveal that H2O2 formed in situ cannot be quantitatively correlated with the degradation of the pollutant.
TL;DR: Interestingly, the estimated fluorescence linear diattenuation and polarizance parameters were considerably reduced in the precancerous tissues as compared to the normal ones.
Abstract: Quantitative fluorescence spectroscopic Mueller matrix measurements from the connective tissue regions of human cervical tissue reveal intriguing fluorescence diattenuation and polarizance effects. Interestingly, the estimated fluorescence linear diattenuation and polarizance parameters were considerably reduced in the precancerous tissues as compared to the normal ones. These polarimetry effects of the autofluorescence were found to originate from anisotropically organized collagen molecular structures present in the connective tissues. Consequently, the reduction of the magnitude of these polarimetric parameters at higher grades of precancer was attributed to the loss of anisotropic organization of collagen, which was also confirmed by control experiments. These results indicate that fluorescence spectral diattenuation and polarizance parameters may serve as potentially useful diagnostic metrics.
TL;DR: In this paper, marine benthic vibrios were used to degrade polyvinyl alcohol-low linear density polyethylene (PVA-LLDPE)-blended plastic films in shake flask conditions at 120rpm at 37°C over 15 weeks.
Abstract: Marine bacteria, Vibrio
alginolyticus and Vibrio
parahemolyticus isolated from sediments were evaluated for their ability as a consortia, to degrade polyvinyl alcohol-low linear density polyethylene (PVA-LLDPE)-blended plastic films in shake flask conditions at 120 rpm at 37 °C over 15 weeks. Results indicated that relatively 20 % decrease in tensile strength of the film could be achieved with 25 and 30 % blend of PVA in the PVA-LLDPE plastic film compared to other ratios. Micrographs obtained with scanning electron microscope showed visible cracks and grooves on the surface of the PVA-LLDPE blend film after 15 weeks of incubation with bacterial consortium. The decrease in tensile strength of the PVA-blended plastic films after treatment and the results of the scanning electron microscopic analysis evidence that the consortium could cause degradation of PVA-LLDPE plastic blends compared to suitable controls. This is the first report on polyvinyl alcohol degrading Vibrio sp. from marine sediments and its application in microbial degradation of polyvinyl alcohol-low linear density polyethylene plastic blends. The study indicated potential of marine benthic vibrios that have novel enzymes and unique characteristics for application in bioremediation and solid waste management particularly in handling synthetic polymers such as PVA-blended plastic films.
TL;DR: In this article, the voltammetric behavior of synthetic food colourant, amaranth, was studied using a multiwalled carbon nanotube (MWCNT) thin film-modified gold electrode in 0.1 M acetate buffer solution of pH 5.0.
Abstract: The voltammetric behaviour of synthetic food colourant, amaranth, was studied using a multiwalled carbon nanotube (MWCNT) thin film-modified gold electrode in 0.1 M acetate buffer solution of pH 5.0. A well-defined oxidation peak was obtained for amaranth at 0.792 V with the modified electrode. The diffusion controlled oxidation of amaranth at the modified electrode can be attributed to the electrocatalytic nature of MWCNT, since the bare electrode has not produced an electrochemical signal under the same experimental conditions. The operational parameters such as supporting electrolyte, pH of the solution and amount of MWCNT–Nafion suspension were optimised. Under optimum conditions, the oxidation peak current varies linearly with concentration in the range from 1.0 × 10−5 M to 1.0 × 10−6 M with a limit of detection at 6.8 × 10−8 M. The developed sensor has good sensitivity and selectivity towards oxidation of amaranth. The sensor was successfully employed for the determination of amaranth in three different samples of soft drinks, and the results were in good agreement with the standard spectrophotometric method.
TL;DR: In this article, a single layer electromagnetic wave absorber was designed by incorporating appropriate amounts of carbon black in a nitrile butadiene rubber matrix along with an optimized amount of magnetic counterpart, namely, barium hexaferrite for applications in S, C, and X-bands.
Abstract: Flexile single layer electromagnetic wave absorbers were designed by incorporating appropriate amounts of carbon black in a nitrile butadiene rubber matrix along with an optimized amount of magnetic counterpart, namely, barium hexaferrite for applications in S, C, and X-bands. Effective dielectric permittivity and magnetic permeability were measured using cavity perturbation method in the frequency range of 2–12 GHz. The microwave absorbing characteristics of the composites were studied in the S, C, and X-bands employing a model in which an electromagnetic wave is incident normally on a metal terminated single layer. Reflection loss exceeding −20 dB is obtained for all the samples in a wide frequency range of 2–12 GHz when an appropriate absorber thickness between 5 and 9 mm is chosen. The impact of carbon black is clearly observed in the optimized composites on the mechanical strength, thickness, band width of absorption, dielectric properties, and absorptivity.
TL;DR: In this article, an ENR-modified epoxy resin resin was used as a modifier for an anhydride hardener/epoxy monomer mixture, resulting in the formation of a phase-separated structure consisting of rubber domains dispersed in the epoxy rich phase.
Abstract: Epoxidized natural rubbers (ENRs) were prepared. ENRs with different concentrations of up to 20 wt % were used as modifiers for epoxy resin. The epoxy monomer was cured with nadic methyl anhydride as a hardener in the presence of N,N-dimethyl benzyl amine as an accelerator. The addition of ENR to an anhydride hardener/epoxy monomer mixture gave rise to the formation of a phase-separated structure consisting of rubber domains dispersed in the epoxy-rich phase. The particle size increased with increasing ENR content. The phase separation was investigated by scanning electron microscopy and dynamic mechanical analysis. The viscoelastic behavior of the liquid-rubber-modified epoxy resin was also evaluated with dynamic mechanical analysis. The storage moduli, loss moduli, and tan δ values were determined for the blends of the epoxy resin with ENR. The effect of the addition of rubber on the glass-transition temperature of the epoxy matrix was followed. The thermal stability of the ENR-modified epoxy resin was studied with thermogravimetric analysis. Parameters such as the onset of degradation, maximum degradation temperature, and final degradation were not affected by the addition of ENR. The mechanical properties of the liquid-natural-rubber-modified epoxy resin were measured in terms of the fracture toughness and impact strength. The maximum impact strength and fracture toughness were observed with 10 wt % ENR modified epoxy blends. Various toughening mechanisms responsible for the enhancement in toughness of the diglycidyl ether of the bisphenol A/ENR blends were investigated. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 39906.