Kalayu Belay

Translocation of Cell Penetrating Peptide Engrafted Nanoparticles Across Skin Layers

The objective of the current study was to evaluate the ability of cell penetrating peptides (CPP) to translocate the lipid payload into the skin layers. Fluorescent dye (DID-oil) encapsulated nano lipid crystal nanoparticles (FNLCN) were prepared using Compritol, Miglyol and DOGS-NTA-Ni lipids by hot melt homogenization technique. The FNLCN surface was coated with TAT peptide (FNLCNT) or control YKA peptide (FNLCNY) and in vitro rat skin permeation studies were performed using Franz diffusion cells. Observation of lateral skin sections obtained using cryotome with a confocal microscope demonstrated that skin permeation of FNLCNT was time dependent and after 24h, fluorescence was observed upto a depth of 120 microm which was localized in the hair follicles and epidermis. In case of FNLCN and FNLCNY formulations fluorescence was mainly observed in the hair follicles. This observation was further supported by confocal Raman spectroscopy where higher fluorescence signal intensity was observed at 80 and 120 microm depth with FNLCNT treated skin and intensity of fluorescence peaks was in the ratio of 2:1:1 and 5:3:1 for FNLCNT, FNLCN, and FNLCNY treated skin sections, respectively. Furthermore, replacement of DID-oil with celecoxib (Cxb), a model lipophilic drug showed similar results and after 24h, the CXBNT formulation increased the Cxb concentration in SC by 3 and 6 fold and in epidermis by 2 and 3 fold as compared to CXBN and CXBNY formulations respectively. Our results strongly suggest that CPP can translocate nanoparticles with their payloads into deeper skin layers.

The thermal conductivity of polycrystalline diamond films: Effects of isotope content

The thermal conductivities of two polycrystalline diamond films made by chemical‐vapor‐deposition process have been measured from a temperature of 15–550 K by using a standard steady‐state technique. While one of the samples was of natural abundance composition (98.9% 12C and 1.1% 13C) the second sample was composed of 50% of each carbon isotope. Around room temperature the thermal conductivity of the natural abundant diamond film for heat flow parallel to the plane was found to be more than three times higher than that of the sample that contained equal amounts of each 12C and 13C isotopes. The results are interpreted in terms of the Klemens–Callaway model for thermal conductivity of solids as a function of temperature.

Interaction of turbulent plasma flow with a hypersonic shock wave

A transient increase is observed in both the spectral energy decay rate and the degree of chaotic complexity at the interface of a shock wave and a turbulent ionized gas. Even though the gas is apparently brought to rest by the shock wave, no evidence is found either of prompt relaminarization or of any systematic influence of end-wall material thermal conductivities on the turbulence parameters.

A comparative study of small 3d-metal oxide (FeO)n, (CoO)n, and (NiO)n clusters

Geometrical and electronic structures of the 3d-metal oxide clusters (FeO)n, (CoO)n, and (NiO)n are computed using density functional theory with the generalized gradient approximation in the range of 1 ≤ n ≤ 10. It is found that the cluster geometries are similar in the (FeO)n and (CoO)n series but noticeably different in the (NiO)n series for several values of n. All of the lowest total energy states are found to possess relatively small spin multiplicities and are either antiferromagnetic or ferrimagnetic except for the states of (NiO)3, (NiO)4, (NiO)9, and (NiO)10, which are ferromagnetic. The computed polarizabilities per atom undergo a steep decrease when compared to the atomic values of the MO monomers (M = Fe, Co, and Ni). Surprisingly, the polarizability does not strongly depend on either M or n in all the considered series when n varies from 3 to 10. The binding energies per atom are the largest in the (FeO)n series, followed by the binding energies of (CoO)n and (NiO)n.

Structure and properties of iron oxide clusters: From Fe6 to Fe6O20 and from Fe7 to Fe7O24

Geometrical and electronic structures of the neutral and singly negatively charged Fe6On and Fe7Om clusters in the range of 1 ≤ n ≤ 20 and 1 ≤ m ≤ 24, respectively, are computed using density functional theory with the generalized gradient approximation. The largest clusters in the two series, Fe6O20 and Fe7O24, can be described as Fe(FeO4)5 and Fe(FeO4)6 or alternatively as [FeO5](FeO3)5 and [FeO6](FeO3)6, respectively. The Fe6O20 and Fe7O24 clusters possess adiabatic electron affinities (EAad) of 5.64 eV and 5.80 eV and can be attributed to the class of hyperhalogens since FeO4 is an unique closed‐shell superhalogen with the EAad of 3.9 eV. The spin character of the lowest total energy states in both series changes from ferromagnetic to ferrimagnetic or antiferromagnetic when the first FeOFe bridge is formed. Oxidation decreases substantially the polarizability per atom of the initial bare clusters; namely, from 5.98 Å3 of Fe6 to 2.47 Å3 of Fe6O20 and from 5.67 Å3 of Fe7 to 2.38 Å3 of Fe7O24. The results of our computations pertaining to the binding energies of O, Fe, O2, and FeO in the Fe7Om series provide an explanation for the experimentally observed abundance of the iron oxide nanoparticles with stoichiometric compositions.

Foil Strain Gauges Using Piezoresistive Carbon Nanotube Yarn: Fabrication and Calibration

Carbon nanotube yarns are micron-scale fibers comprised by tens of thousands of carbon nanotubes in their cross section and exhibiting piezoresistive characteristics that can be tapped to sense strain. This paper presents the details of novel foil strain gauge sensor configurations comprising carbon nanotube yarn as the piezoresistive sensing element. The foil strain gauge sensors are designed using the results of parametric studies that maximize the sensitivity of the sensors to mechanical loading. The fabrication details of the strain gauge sensors that exhibit the highest sensitivity, based on the modeling results, are described including the materials and procedures used in the first prototypes. Details of the calibration of the foil strain gauge sensors are also provided and discussed in the context of their electromechanical characterization when bonded to metallic specimens. This characterization included studying their response under monotonic and cyclic mechanical loading. It was shown that these foil strain gauge sensors comprising carbon nanotube yarn are sensitive enough to capture strain and can replicate the loading and unloading cycles. It was also observed that the loading rate affects their piezoresistive response and that the gauge factors were all above one order of magnitude higher than those of typical metallic foil strain gauges. Based on these calibration results on the initial sensor configurations, new foil strain gauge configurations will be designed and fabricated, to increase the strain gauge factors even more.

Foil Strain Gauge Sensors of Piezoresistive Carbon Nanotube Yarn: Fabrication and Calibration

Carbon nanotube yarns are micron-scale fibers comprised by tens of thousands of carbon nanotubes in their cross section and exhibiting piezoimpedance characteristics that can be tapped to sense strain. This paper presents the details of novel foil-based strain gauge sensor configurations comprising carbon nanotube yarn. The strain gauge sensors were designed considering parametric studies that maximize the sensitivity of the sensor to mechanical loading. The fabrication details of the strain gauge sensors that exhibit the highest sensitivity, based on the modeling results, are described including the materials and procedures used in the first prototypes. Details of the calibration of the strain gauge sensors are also provided and discussed in the context of the electromechanical characterization when bonded to metallic specimens. This characterization included studying their response under monotonic and cyclic loading. It is shown that these strain gauge sensors consisting of carbon nanotube yarn are sensitive enough to capture strain. Previous modeling results indicated the potential of the strain gauges to exhibit gauge factors higher than those of metallic foil strain gauges.

Modification of Magnetic Properties of Iron Clusters by Doping and Adsorption: From a Few Atoms to Nanoclusters

Electronic and geometrical structure of neutral and charged iron clusters Fe n , \({\text{Fe}}_{n}^{ - }\), and \({\text{Fe}}_{n}^{ + }\) (n = 2–20) will be discussed. Computational results will be compared to experimental data, in particular, to the recent data obtained from the magnetic moment measurements of \({\text{Fe}}_{n}^{ + }\). We consider iron cluster oxides, single Fe atom oxides FeO n for n up to 12, and FeX n superhalogens. We present the results of computational simulations of gas-phase interactions between small iron clusters and OH, N2, CO, NO, O2, and H2O. Competition between surface chemisorption and cage formation in Fe12O12 clusters will be discussed. The magnetic quenching found in Fe12O12 will be qualitatively explained using the natural bond orbital analysis performed on Fe2O2. Special attention will be paid to the structural patterns of carbon chemisorbed on the surface of a ground-state Fe13 cluster.