Femtosecond Photoexcited Carrier Dynamics in Reduced Graphene Oxide Suspensions and Films

We report ultrafast response of femtosecond photoexcited carriers in single layer reduced graphene oxide flakes suspended in water as well as few layer thick film deposited on indium tin oxide coated glass plate using pump-probe differential transmission spectroscopy at 790 nm. The carrier relaxation dynamics has three components: ~200 fs, 1 to 2 ps, and ~25 ps, all of them independent of pump fluence. It is seen that the second component (1 to 2 ps) assigned to the lifetime of hot optical phonons is larger for graphene in suspensions whereas other two time constants are the same for both the suspension and the film. The value of third order nonlinear susceptibility estimated from the pump-probe experiments is compared with that obtained from the open aperture Z-scan results for the suspension.Comment: 4 pages, 4 figures, to appear in International Journal of Nanoscience (IJN), 201

Femtosecond carrier dynamics and saturable absorption in graphene suspensions

Nonlinear optical properties and carrier relaxation dynamics in graphene, suspended in three different solvents, are investigated using femtosecond (80 fs pulses) Z-scan and degenerate pumpprobe spectroscopy at 790 nm. The results demonstrate saturable absorption property of graphene with a nonlinear absorption coefficient, $beta$, of ~2 to 9x10^-8 cm/W. Two distinct time scales associated with the relaxation of photoexcited carriers, a fast one in the range of 130-330 fs (related to carrier-carrier scattering) followed by a slower one in 3.5-4.9 ps range (associated with carrier-phonon scattering) are observed.Comment: 3 pages, 2 figures, 2 table

Detection of Sugar-Lectin Interactions by Multivalent Dendritic Sugar Functionalized Single-Walled Carbon Nanotubes

We show that single walled carbon nanotubes (SWNT) decorated with sugar functionalized poly (propyl ether imine) (PETIM) dendrimer is a very sensitive platform to quantitatively detect carbohydrate recognizing proteins, namely, lectins. The changes in electrical conductivity of SWNT in field effect transistor device due to carbohydrate - protein interactions form the basis of present study. The mannose sugar attached PETIM dendrimers undergo charge - transfer interactions with the SWNT. The changes in the conductance of the dendritic sugar functionalized SWNT after addition of lectins in varying concentrations were found to follow the Langmuir type isotherm, giving the concanavalin A (Con A) - mannose affinity constant to be 8.5 x 106 M-1. The increase in the device conductance observed after adding 10 nM of Con A is same as after adding 20 \muM of a non - specific lectin peanut agglutinin, showing the high specificity of the Con A - mannose interactions. The specificity of sugar-lectin interactions was characterized further by observing significant shifts in Raman modes of the SWNT.Comment: 12 pages, 3 figure

A Study on “Security of Cyber-Physical Systems in the Cloud”

The existing security models are built with certain assumptions. The solutions like distributed accountability, provable data possession (PDP), Third Party Auditing (TPA) and so on are secure as long as the assumptions hold true. To ensure fool proof security for cloud storage security little research has been made on quantum key cryptography. Since the quantum key distribution is unconditionally secure, we propose a new scheme known as Cloud QKDP (Quantum Key Distribution Protocol for Cloud Computing) which exploits the benefits of quantum mechanisms to secure cloud storage and data dynamics. We consider a case study in which three parties such as cloud server, data owner and trusted client have provably secure communications with our proposed scheme which uses random oracle model. Our empirical study revealed mixture of success and failure rates with private and public clouds respectively

Cold Atmospheric Pressure Argon Plasma Jet Assisted Degradation of Malachite Green (MG) Aqueous Solution

The oxidative degradation of cold atmospheric pressure plasma assisted degradation of malachite Green (MG) was investigated in this study. Cold atmospheric pressure plasma assisted MG degradation process was carried out as a function various plasma treatment time (05, 10, and 15 mins). The % of degradation and presence carbon content in the plasma treated MG was examined by UV-Visible spectroscopy (UV-Vis) and total organic carbon (TOC) analyzer. Optical emission spectrometer was used to identify formation of various reactive species during in situ plasma treatment. The higher degradation percentage of 90% was obtained after plasma treatment time of 15 min and value of TOC also found to decreased significantly with increasing plasma treatment time.  Toxicity of the plasma-treated MG aqueous solution samples was also examined by Staphylococcus aureus (S.aureus) bacteria

3D-QSAR studija afiniteta vezanja na receptor za (R,S)-2-amino-3-(3-hidroksi-5-metilizoksazol-4-il)-propansku kiselinu

An approach for binding affinity evaluation is suggested and exemplified using a set of triazolo [1,5-a] quinoxaline for the (R,S)-2-amino-3-(3-hydroxy-5-methylisoxazol-4-yl)-propionic acid (AMPA) receptor. Biological activity toward the AMPA receptor (expressed as -log IC5O) was taken as a dependent variable for building Comparative Molecular Field Analysis (CoMFA) and Comparative Molecular Similarity Indices Analysis (CoMSIA) models. The resulting models show the ways of increasing the binding affinity to the AMPA receptor as a potential target for epilepsy. The statistically significant results show that the cross-validated r2CV value (0.766) for the CoMFA model is greater than (0.758) for the CoMSIA model. The non-cross validated run giving the coefficient of determination r2 values of 0.944 and 0.919 for CoMFA and CoMSIA, respectively, provided good correlation between the observed and computed affinities of the training set compounds. The resulting CoMFA and CoMSIA models indicate that steric, electrostatic, hydrophobic (lipophilic), hydrogen bond donor and acceptor substituents play a significant role in increasing the binding affinity and selectivity of the compounds toward the AMPA receptor.U radu je vrednovan afinitet vezanja serije triazolo[1,5-a]kinoksalina na receptor za (R,S)-2-amino-3-(3-hidroksi-5-metilizoksazol-4-il)-propansku kiselinu (AMPA). Djelovanje na AMPA receptor (izraženo kao log IC5O) uzeta je kao zavisna varijabla u modelima usporedne analize molekulskih polja (Comparative Molecular Field Analysis, CoMFA) i usporedne analize molekulske sličnosti (Comparative Molecular Similarity Indices Analysis, CoMSIA). Ti modeli pokazuju kako povećati afinitet vezanja na AMPA receptor, što može biti korisno u terapiji epilepsije. Statistički značajni rezultati ukazuju da je križno validirana r2CV vrijednost za CoMFA model (0,766) veća nego za CoMSIA model (0,758). Koeficijenti r2 za CoMFA model (0,944) i CoMSIA (0,919) ukazuju na dobru korelaciju između izračunatih i eksperimentalno određanih afiniteta vezanja proučavane serije spojeva. Prema oba modela za povećanje afiniteta vezanja i selektivnost spojeva za AMPA receptor značajna su sterička, elektrostatska, hidrofobna (lipofilni) svojstva, te sposobnost stvaranja vodikovih veza

Applications of nanomedicine in antibacterial medical therapeutics and diagnostics

The need for new and effective/efficient antibacterial therapeutics and diagnostics is necessary if we want to be able to maintain and improve the protection against pathogenic bacteria. Bacteria are becoming increasingly resistant to traditionally used antibiotics and as a result are a major health concern. The number of deaths and hospitalizations due to bacteria is increasing. Current methods of bacterial diagnostics are inefficient as they lack speed and ultra sensitivity and cannot be performed on site. This is where nanomedicine is playing a vital role. The discovery of new and innovative materials through the improvement in fabrication techniques has seen the establishment of an influx of novel antibacterial therapeutics and diagnostics. The goal of this review is to highlight the research that has been done through the implementation of nanomaterials and nanotechnologies for antibacterial medical therapeutic and diagnostic.<br /

A Cross-sectional study on Out-of-Pocket expenditure towards Immunization and its consequences faced by families with under-five Children Residing at one of the Cities of Western India

Background: When immunization of under-five children results in Out-of-Pocket Expenditure (OOPE), it affects motivation of parents for vaccination inversely. Objectives: To assess determinants affecting preference for specific/mixed type of health facilities and to estimate out-of-pocket expenditure towards immunization of under-five children. To assess opinion of participants for prevention/decreasing OOPE towards immunization. Methods: A community-based cross-sectional study was conducted at one of zones of Ahmedabad city, selected by simple random sampling. Following technique of “30×7 cluster survey” with necessary house-hold information received from Municipal Corporation, selection of 7 children was pursued from each cluster reaching to sample-size of 210 (30 X 7). Results: Of 211 children included in study, 124(58.77%), 68(32.23%) and 19(9%) had taken immunization services from government, private and mixed variety respectively. Majority of families (110, 88.71%) preferring government healthcare-facility for immunization incurred expenses &lt;5000 INR/child as while in other two groups, all beneficiaries had expensed&gt;5000 INR/child. Conclusions: Determinants like child’s gender, parents’ education, Type of family, Socio-economic status, delivery place of child and occupation of father had statistically significant association with preferred place of vaccination. Fixation of upper ceiling-limit of vaccines which are recommended by pediatricians but not covered in government run program was one of suggestions