Graphene oxide dielectric permittivity at GHz and its applications for wireless humidity sensing

Graphene oxide relative dielectric permittivity, both its real and imaginary parts, have been measured under various humidity conditions at GHz. It is demonstrated that the relative dielectric permittivity increases with increasing humidity due to water uptake. This electrical property of graphene oxide was used to create a battery-free wireless radio-frequency identification (RFID) humidity sensor by coating printed graphene antenna with the graphene oxide layer. The resonance frequency as well as the backscattering phase of such graphene oxide/graphene antenna become sensitive to the surrounding humidity and can be detected by the RFID reader. This enables batteryless wireless monitoring of the local humidity with digital identification attached to any location or item and paves the way for low-cost efficient sensors for Internet of Things applications

Effects of occurrence data density on conservation prioritization strategies

Place-prioritization analyses are a means by which researchers can translate information on the geographic distributions of species into quantitative prioritizations of areas for biodiversity conservation action. Although several robust algorithms are now available to support this sort of analysis, their vulnerability to biases deriving from incomplete and imbalanced distributional information is not well understood. In this contribution, we took a well-sampled group (i.e., Icteridae or New World blackbirds) in an intensively sampled region (the contiguous continental United States), and developed a set of pseudo-experimental manipulations of occurrence data density—in effect, we created situations in which data density was reduced 10- or 100-fold, and situations in which data density varied 100-fold from region to region. The effects were marked: priority areas for conservation shifted, appeared, and disappeared as a function of our manipulations. That is, differences in density of data can affect the position and complexity of areas of high conservation priority that are identified using distributional areas of species derived from ecological niche modeling. The effects of data density on prioritizations become more diffuse when considerations of existing protected areas and costs related to human intervention are taken into account, but changes are still manifested. Appropriate considerations of sampling density when constructing ecological niche models to identify distributional areas of species are key to preventing artifactual biases from entering into and affecting results of analyses of conservation priority

Atomic structure and properties of graphene and novel graphene derivatives

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

An evaluation of the ecological niche of Orf virus (Poxviridae): Challenges of distinguishing broad niches from no niches.

Contagious ecthyma is a skin disease, caused by Orf virus, creating great economic threats to livestock farming worldwide. Zoonotic potential of this disease has gained recent attention owing to the re-emergence of disease in several parts of the world. Increased public health concern emphasizes the need for a predictive understanding of the geographic distributional potential of Orf virus. Here, we mapped the current distribution using occurrence records, and estimated the ecological niche in both geographical and environmental spaces. Twenty modeling experiments, resulting from two- and three-partition models, were performed to choose the candidate models that best represent the geographic distributional potential of Orf virus. For all of our models, it was possible to reject the null hypothesis of predictive performance no better than random expectations. However, statistical significance must be accompanied by sufficiently good predictive performance if a model is to be useful. In our case, omission of known distribution of the virus was noticed in all Maxent models, indicating inferior quality of our models. This conclusion was further confirmed by the independent final evaluation, using occurrence records sourced from the Centre for Agriculture and Bioscience International. Minimum volume ellipsoid (MVE) models indicated the broad range of environmental conditions under which Orf virus infections are found. The excluded climatic conditions from MVEs could not be considered as unsuitable owing to the broad distribution of Orf virus. These results suggest two possibilities: that the niche models fail to identify niche limits that constrain the virus, or that the virus has no detectable niche, as it can be found throughout the geographic distributions of its hosts. This potential limitation of component-based pathogen-only ENMs is discussed in detail

Evolutionary history of Kingiodendron pinnatum (Fabaceae: Caesalpinoideae), an endangered species of Western Ghats, India: A phylogeographical approach

Palaeoclimatic conditions and the Palghat Gap (PG), an ancient geological break, influence structuring of genetic diversity in the Western Ghats (WG) of India. The present study describes the first approach of its kind on a plant species in the WG to decipher its evolutionary history by testing three hypotheses: (1) PG acts as a geographical barrier and forms two distinct phylogroups; (2) speciation and diversification occurred before Pleistocene glaciations; and (3) no distributional shifts have occurred since the late Pleistocene. The trnH?psbA and trnL?trnF markers were sequenced from leaf samples of Kingiodendron pinnatum collected from 14 populations across its geographical distribution. Two divergent haplogroups were found to the North and South of PG, with 13 and 12 haplotypes, respectively. A dated phylogenetic tree of haplotypes reveals the time of divergence between these groups as ~14.62 Mya. Diffusion analysis predicts the most probable origin of diversification to be in central Kerala. Niche modelling suggests that the potential distributional range of K. pinnatum in the present conditions covers a larger area than that predicted for the Last Glacial Maximum. Thus, only the first and second hypotheses are accepted. The predicted future distribution suggests that two subgroups in the southern group should be treated as evolutionarily significant unitsFil: Raveendran Nair, Rahul. Centre For Evolutionary Ecology, Aushmath,biosciences; IndiaFil: Karumathil, Sudeesh. Centre for Evolutionary Ecology, Aushmath Biosciences; IndiaFil: Udayan, Punnakkal Sreedharan. Department Of Botany, Sree Krishna College; IndiaFil: Prakashkumar, Raveendran Pillai. Centre for Evolutionary Ecology, Aushmath Biosciences; IndiaFil: Sersic, Alicia Noemi. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; Argentin

Probing Photoexcited Carriers in a Few-Layer MoS2 Laminate by Time-Resolved Optical Pump–Terahertz Probe Spectroscopy

We report the dynamics of photoinduced carriers in a free-standing MoS₂ laminate consisting of a few layers (1–6 layers) using time-resolved optical pump–terahertz probe spectroscopy. Upon photoexcitation with the 800 nm pump pulse, the terahertz conductivity increases due to absorption by the photoinduced charge carriers. The relaxation of the non-equilibrium carriers shows fast as well as slow decay channels, analyzed using a rate equation model incorporating defect-assisted Auger scattering of photoexcited electrons, holes, and excitons. The fast relaxation time occurs due to the capture of electrons and holes by defects <i>via</i> Auger processes, resulting in nonradiative recombination. The slower relaxation arises since the excitons are bound to the defects, preventing the defect-assisted Auger recombination of the electrons and the holes. Our results provide a comprehensive understanding of the non-equilibrium carrier kinetics in a system of unscreened Coulomb interactions, where defect-assisted Auger processes dominate and should be applicable to other 2D systems

RAPD markers for screening shoot gall maker (Betousa stylophora Swinhoe) tolerant genotypes of amla (Phyllanthus emblica L.)

Phyllanthus emblica Linn. is the most important medicinally useful tree crop in Asian Subcontinent and is severely infested by Betousa stylophora Swinhoe, known as shoot gall maker (SGM). This pest tunnels the shoots of seedlings and actively growing branches of trees and develops gall, leading to stunted growth, unusual branching and death of actively growing shoots. Our study revealed that trees possessing smooth bark were free from the attack of this pest than those with rough bark surface. Unfortunately, this character is not detectable either at seedling stage or during early growth of trees in the orchard. RAPD genetic fingerprinting of trees possessing smooth and rough bark revealed distinguishable and highly reproducible DNA banding pattern between the two genotypes. Of the 20 RAPD primers tested, five of them produced distinguishable RAPD bands between rough and smooth barked genotypes of P. emblica. Trees with smooth bark produced five unique RAPD bands with molecular weight ranging from 350 bp to 1500 bp and those with rough bark produced six RAPD bands (350 bp–650 bp) to utilize these DNA bands as potential DNA marker for screening tolerant genotypes of this crop against SGM. The utility of this finding in genetic improvement of this tree crop against SGM is discussed