1,733 research outputs found
Biomimetic multifunctional materials: a review
No full textInspired from nature, material scientists design and fabricate fascinating multifunctional composites for various applications. The profound insight on hierarchical micro/nanostructures or biological functions behind biomimetic properties and functions and their proper integration in a material for specific applications are crucial in developing biomimetic multifunctional composites. The current review discusses in detail the integration of potentially relevant biomimetic properties and/or functions such as self-cleaning with anti-reflection, self-cleaning with anti-corrosion, self-healing with self-cleaning, shape memory and wettability, super strong and tough, and self-healing with super tough. This review also outlines potential applications of such multifunctional composites in biomedical, oil-gas industry, aviation, marine, wearable electronics, fabrics, sensors, energy harvesting devices, and many more
Ca. 820-640 Ma SIMS U-Pb age signal in the peripheral Vijayan Complex, Sri Lanka: Identifying magmatic pulses in the assembly of Gondwana
No full textSri Lanka comprises three roughly north-south trending amphibolite- to granulite-facies lithotectonic complexes, from west to east the Highland Complex, the Wanni Complex, and the Vijayan Complex. These terranes were correlated with other East Gondwana continental terranes with similar lithologies forming at similar ages. The Wanni Complex and the Vijayan Complex have been interpreted as volcanic arc terranes brought together by a double-sided subduction. The Highland Complex represents the metamorphosed accretionary prism within the suture when the Wanni and Vijayan Complexes were juxtaposing against each other. In contrast to the Wanni and Highland Complexes, the Vijayan Complex has yielded only a few geochronological data with satisfactory precision. Previous studies suggested that the Vijayan Complex comprises ∼1100–924 Ma granitic gneisses, which were metamorphosed during ∼590–456 Ma. More recently, ∼772–617 Ma mafic intrusions have been identified. This study divides the Vijayan granitic gneisses and the associated melt products geochemically into a low-Nb series and a more primitive high-Nb series. Our SIMS U-Pb zircon data suggested that both series have protolith magmatic ages of ∼1062–935 Ma, and metamorphic ages of ∼580–521 Ma, which is consistent with previous work. However, some of the Vijayan granitic gneisses and granitic anatectic melt products at the Highland-Vijayan tectonic mixed zone preserve an additional Tonian-Cryogenian (∼820–630 Ma) age signal. This age signal suggested that felsic magmatism also occurred when mafic granulites were emplaced along the Highland-Vijayan boundary, which is broadly coeval with to the bimodal magmatism occurring along the Highland-Wanni boundary. This study also suggests that charnockitisation in the Vijayan Complex occurred at 562 ± 6 Ma during the Neoproterozoic regional metamorphism. The Tonian-Cryogenian signal preserved in the Highland-Vijayan tectonic mixed zone can also be found in the alkaline intrusion hosted by the Namuno Terrane and the Lurio Belt in Mozambique. This indicates a relationship between the Vijayan granitic gneisses and the Lurio foreland metagranitic basement, while the Namuno Terrane and the Lurio Belt are correlated with the Highland-Vijayan tectonic mixed zone. The ages and the isotope signatures of these granitic bodies further suggest a genetic relationship of these granitic bodies with various magmatic intrusions in East Antarctica.</p
Geochemistry and SIMS U-Pb zircon geochronology of the Vijayan anatectic melts of eastern Sri Lanka.
No full textSri Lanka comprises three roughly north-south trending lithotectonic complexes, from west to east the Highland Complex, the Wanni Complex, and the Vijayan Complex. They are made up of amphibolite- to granulite-facies metamorphic rocks. The origin of these complexes is not well-established, and correlations can be tested by comparing their geochemistry, age, and isotope signatures with other well-known tectonic units. Timing, geochemistry and pressure-temperature (P-T) conditions of the western metamorphic complexes have been previously studied, and reported by numerous workers as summarized in Santosh et al. [1]. The Highland Complex has been interpreted as a stable fragment of the Columbian supercontinent, while it is suggested that the Wanni Complex is a volcanic arc terrane accreted while in proximity to the terranes of East Africa [2][3]. Meanwhile, the origin of the Vijayan Complex is still mysterious. Geological research on this part of Sri Lanka has been hindered by civil war. Although geochronological and geochemical data of the metamorphic basement are now available [4], these data are not sufficient to reveal its origin. This poster reviews data obtained by previous workers, and provides new preliminary geochemical data as well as SIMS U-Pb zircon ages, suggesting that the geochemistry and age signatures of the anatectic melt generated during Vijayan Complex metamorphism may be more meaningful than previously thought.
The associated granitic anatectic melts are biotite- and hornblende-bearing. The mineral assemblage is typical for I-type granite in a broad sense. This association is supported by geochemical and positive Nd isotopic data. However, two series of anatectic melts are identified in our samples from the Vijayan Complex. One is the ordinary metaluminous to weakly peraluminous I-type granite or granodiorite, which are dated within the widely reported age range of 1100-1050 Ma [4]. The other one is solely metaluminous granodiorite, which has a higher high field strength elements (HFSE) content. Some of these latter granodiorites contain zircons that include a significant 550 Ma age population, which could be related to metamorphism associated with the Pan-African orogeny. Our preliminary SIMS U-Pb zircon ages suggest some of these granodioritic bodies in the southern Vijayan Complex also indicate a protolith age of 790 Ma, which has not been thoroughly discussed in previous literature. Apparently, these bodies are restricted to the controversial Highland-Vijayan mixing zone of the western Vijayan Complex. Similar results have been obtained for the Wanni Complex and potentially related terranes in East Africa. Continuing research on these melts might redefine the boundary of the Vijayan Complex,
provide further clues to the origin of the Vijayan Complex, and refine its relationship with the Highland Complex.
References:
[1] Santosh M et al. (2014) Precambrian Research 255(1): 1-29
[2] Kehelpannala KVW (2004) Gondwana Research 7(4S): 41-46
[3] Kröner A et al. (2003) Journal of Asian Earth Sciences 22(3): 279-300
[4] Kröner A et al. (2013) Precambrian Research 234(1): 288-32
Paramicrolaimus damodarani Jacob, Jaleel & Vijayan, 2015, sp. nov.
No full textDescription of Paramicrolaimus damodarani sp. nov. (Figs 2–4) Material examined. Holotype, two paratype males and two juveniles [Slide No.IO/SS/NEM/00021; Deposited at FORV Referral Centre, Centre for Marine Living Resources and Ecology, Kochi, Kerala, India.] collected from continental margin of south eastern Arabian Sea. Type locality. Holotype and paratype males: Continental margin of south eastern Arabian Sea—off Kannur, 11 ° 45 ’ 02” N, 74 ° 41 ’ 47 ” E, 95 m, 11.02. 2012 (FORVSS 295). Two juveniles: South eastern Arabian Sea—off Cape Comorin, 7 ° 09’ 12 ” N, 77 ° 19 ’ 14 ” E, 207 m, 21.04. 2005 (FORVSS 233). Sediment texture was silt with low percentages of clay, bottom temperature 26.6 °C, bottom salinity 35.65 psu, bottom dissolved oxygen concentration 2.98 ml/l. Description. Holotype (male): Body cylindrical, long and thread like. Total body length 1280 µm, a = 51.2, b = 9.14, c = 20.32. Body diameter 20 µm at the level of posterior cephalic setae, with maximum 25 µm at mid body and 25 µm at anus. Cuticle thick, striated; striation in the cephalic region weak, distinct at mid body and caudal region. Hypodermal gland cells present. Head without striation, slightly constricted at the level of amphids. Labial sensillae barely visible. Cephalic setae in two separate circles (6 + 4), with similar lengths (13–14 µm). Somatic setae present in cephalic (5 µm) and caudal (7 µm) regions. Buccal cavity irregular, with deep and narrow anterior part and posterior part with sclerotized walls, two teeth present as dorsal and right subventral projections. Amphids wide (11 µm), thick walled, transversely oval-shaped with a small dorsal limb, located 19 µm away from the anterior end. Oesophagus 140 Μm long with swollen anterior end, middle part thin and cylindrical; posterior end swollen resembling a slightly elongated or weak oesophageal bulb (35 Μm long and 10 Μm wide). Males diorchic. Spicules paired, equal in size, 28 µm long, strongly arcuate, proximally cephalate with a distinct ventral, raised keel-like structure at mid-length. Gubernaculum parallel to spicule, simple in shape with lateral wing in the middle part. Seven distally expanded, cuticularised, protruding, precloacal supplements, each with distal thorn-like structures at their tips. First anterior and last posterior precloacal supplements slightly smaller than those between. Tail conoid, attenuated, ventrally coiled; 63 µm in length. Short, broad terminal spinneret present, strongly cuticularised, with long terminal setae arising from it dorsally. Females and Juveniles. Females not found; juveniles resemble males in general morphology (Table 1). Diagnosis. Cuticle finely striated. Conspicuous amphids with thick wall, transversely oval-shaped with a small dorsal limb. Spicules paired, strongly arcuate, proximally cephalate with a distinct central keel. Gubernaculum simple, plate-like, with a lateral wing in the middle part. Seven cuticularised, protruding, ventrally placed precloacal supplements. Tail conoid with a cuticularised terminal spinneret. Relationships. The general shape of the body and the spicular apparatus, position and number of cephalic setae, and position and shape of the amphid place the present specimens in Paramicrolaimus Wieser, 1954 (Figs 2–4; Tables 1 & 2). They are most similar to Paramicrolaimus mirus Tchesunov, 1988 in the general shape of the body, buccal cavity, oesophagus, size and shape of amphid and shape of gubernaculum. Paramicrolaimus damodarani sp. nov. strongly differs from P. mirus in body length (1.28 mm vs 4.06 mm), length of cephalic setae (6 + 8 µm vs 13 + 14–15 µm), a -value (105–106 vs 51–52.4), b - value (21.7–21.8 vs 8.8–9.1), c -value (28–40.5 vs 18.8–20.3), number of precloacal supplements (7 vs 9), shape and size of spicular apparatus (28 µm vs 23 µm), and in having a terminal spinneret which is absent in P. mirus (Figs 2–4, Tables 1 & 2). Specimens of P. mirus from the Yellow Sea (Huang & Zhang, 2005) showed larger measurements in all morphological characters compared with P. damodarani sp. nov. (Table 2). Also, the spicule of P. mirus has a velum (Huang & Zhang 2005) whereas P. damodarani sp. nov. has a central keel at mid-length. The gubernaculum in both the species were plate-shaped with a lateral wing in middle part but is of different size (19 µm vs 18 µm). The spinneret of P. damodarani sp. nov. has strongly cuticularised walls and the setae in the caudal region are longer (Figs 2, 3) than in P. mirus. Paramicrolaimus damodarani sp. nov. can be differentiated from P. spirulifer in being smaller (1.28 mm vs 4.43 mm) in all morphological measurements in addition to the number of precloacal suppliments (7 vs 6) and the shape of the gubernaculum (Figure 2–4; Table 2). While Wieser, 1959 reported 6 precloacal supplements in P. spirulifer, Jensen (1978) counted 10 in the redescription of the species. The gubernaculum in P. spirulifer is weakly sclerotized and apparently surrounds the distal parts of the spicules but in P. damodarani sp. nov. it is plate-shaped with a lateral wing in the middle part. Etymology. The species is named in honour of Prof. R. Damodaran, with deep gratitude and in appreciation of his invaluable contributions to benthic studies in India.Published as part of Jacob, Jini, Jaleel, Abdul & Vijayan, Anil Kumar, 2015, A new species of the rare nematode genus Paramicrolaimus Wieser, 1954 (Chromadorida: Paramicrolaimidae) from the south eastern Arabian Sea, pp. 563-571 in Zootaxa 3904 (4) on pages 566-568, DOI: 10.11646/zootaxa.3904.4.5, http://zenodo.org/record/23306
Effect of organically modified nanoclay on the miscibility, rheology, morphology and physical properties of diglycidyl ether of bisphenol-A epoxy/ carboxyl-terminated (butadiene-co-acrylonitrile) blend
No full textCarboxyl-terminated (butadiene-co-acrylonitrile) (CTBN) modified epoxy/clay nanocomposites (epoxy/clay/CTBN ternary nanocomposites) were synthesized using nadic methyl anhydride as curing agent. Effect of nanoclay on the phase behavior (UCST) of epoxy oligomer/CTBN blend has been studied in detail. The phase diagram was shifted to a higher temperature with increase in clay loading due to the easy penetration of low molecular weight CTBN into the clay galleries. The XRD studies confirmed the penetration of CTBN into the clay galleries, as the ‘ d ’ spacing increased with increase in CTBN content in the epoxy/clay/CTBN ternary nanocomposite. The interaction of organically modified clay with epoxy and CTBN were studied using frequency sweep rheological analysis. The individual and combined effect of nanoclay and CTBN on the cure reaction was followed by isothermal rheological analysis. It was found that complex viscosity profiles during cure reaction follow an exponential growth. The characteristic relaxation time of viscosity growth was described by the WLF equation. Moreover the dynamics of phase separation during cure was followed using optical microscopy. The scanning electron microscopic (SEM) images revealed that the domain size of phase separated CTBN in epoxy/clay/CTBN ternary nanocomposite was smaller than in epoxy/CTBN binary blend. The kinetic factor in epoxy-anhydride cure reaction and the presence of clay at epoxy–CTBN interface was used to explain this size reduction. The high resolution transmission electron microscopic (HRTEM) image of epoxy/3 phr clay nanocomposite showed that the clay platelets were mostly intercalated. Epoxy/3 phr clay/15 phr CTBN nanocomposite has an intercalated with occasional exfoliated microstructure with slightly distorted clay orientation. Low magnification TEM images showed that most of the clay platelets located near the phase separated CTBN and the presence of clay at the epoxy–CTBN interface. The viscoelastic properties of epoxy/clay/CTBN nanocomposite was studied and compared with that of epoxy/clay nanocomposite and epoxy/CTBN blend. A quantitative measurement of constrained region (macromolecular chains immobilized by the clay platelets) was carried out for epoxy/clay and epoxy/clay/CTBN nanocomposites. Finally thermal degradation studies were performed to evaluate the thermal stability of the ternary nanocomposites
Effect of nanoclay and carboxyl-terminated (butadiene-coacrylonitrile) (CTBN) rubber on the reaction induced phase separation and cure kinetics of an epoxy/cyclic anhydride system
No full textThe effects of nano clay, carboxyl-terminated
(butadiene-co-acrylonitrile) (CTBN) liquid rubber and the
combination of both on the cure kinetics of diglycidyl ether
of bisphenol-A (DGEBA)-based epoxy resin/nadic methyl
anhydride were studied. Cure kinetics studies were carried
out by performing dynamic and isothermal differential
scanning calorimetric (DSC) experiments. The dynamic
DSC experiments were carried out at four different heating
rates. Dynamic kinetic modeling was performed using
Kissinger and Ozawa approaches. Since these methods are
based exclusively on the maximum rate of cure, which
occurs approximately at the beginning of the cure reaction,
the activation energy calculated using these methods is
valid only for the initial stage of the cure. The clay (3 phr)
filled epoxy system has an activation energy 24 % lower
than the unfilled system. The role of the surfactant chemistry
on the initial stage of the cure reaction was also
studied. A plausible reaction mechanism which involves
the effect of the nanoclay surfactant as an accelerator of the
cure reaction was proposed. The phase separated CTBN
rubber hindered the cure reaction and has 3 % higher
activation energy for epoxy/CTBN system than the unfilled
system. In the ternary epoxy/3 phr clay/15 phr CTBN
system, the accelerating effect of clay on cure was highlighted.
The cure activation observed in the presence of
clay overshadows the hindrance created by the phase separated
CTBN. Isothermal DSC scans were carried out at
five different temperatures. The experimental datas showed
an autocatalytic behavior of the reaction, and the isothermal
modeling was carried out by Kamal autocatalytic
model. The results showed a very good agreement within
the whole conversion range for the unfilled and all the filled
systems. The evolution of the morphology and phase separation
was also studied using optical and scanning electron
microscope. Faster cure reaction resulted in smaller
phase-separated CTBN particles in epoxy/clay/CTBN ternary
system as compared with those observed in epoxy/
CTBN binary blend
Gangrene of the penis in a diabetic male with multiple amputations and follow up
No full textA 60-year-old insulin dependent, diabetic male with severe atherosclerosis requiring multiple amputations in the extremities in the past, with normal renal function presented with gangrene of glans penis. He was initially treated with debridement but as the gangrene progressed, partial penile amputation was performed. He showed no further progress of the disease and had no voiding difficulties even after 4 years of follow up
Acetogenins from Annona muricata as potential inhibitors of antiapoptotic proteins: a molecular modeling study
No full textPriya Antony, Ranjit Vijayan Department of Biology, College of Science, United Arab Emirates University, Al Ain, Abu Dhabi, United Arab Emirates Abstract: Apoptosis is a highly regulated process crucial for maintaining cellular homeostasis and development. The B-cell lymphoma 2 (Bcl-2) family of proteins play a crucial role in regulating apoptosis. Overexpressed Bcl-2 proteins are associated with the development and progression of several human cancers. Annona muricata is a tropical plant that belongs to the Annonaceae family and is well known for its anticancer properties. In this study, molecular docking and simulations were performed to investigate the inhibitory potential of phytochemicals present in A. muricata against antiapoptotic proteins of the Bcl-2 family including Bcl-2, B-cell lymphoma extra-large (Bcl-Xl), and Mcl-1. Docking results revealed that the acetogenins, such as annomuricin A, annohexocin, muricatocin A, annomuricin-D-one, and muricatetrocin A/B, exhibited strong binding interactions with Bcl-Xl when compared to Bcl-2 and Mcl-1. Binding score and interactions of these acetogenins were notably better than those of currently available synthetic and natural inhibitors. Molecular dynamics simulations of the top-scoring lead molecules established that these molecules could bind strongly and consistently in the active site of Bcl-Xl. These results suggest that acetogenins could be explored as selective natural inhibitors of Bcl-Xl that could assist in promoting the intrinsic pathway of apoptosis. Keywords: apoptosis, molecular docking, molecular dynamics, phytocompounds, drug discover
Ventral urethral diverticulum of fossa navicularis
No full textA rare case of ventral diverticulum of fossa navicularis was encountered in an adult. This has not been reported earlier in the urological literature
Traumatic dislocation of testis
No full textTraumatic dislocation of testis occurs as a consequence of high velocity road traffic accident. We report traumatic testicular dislocation in a young man which was successfully treated with closed reduction under general anesthesia
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