Finite size effects in ZnO nanoparticles: An electron paramagnetic resonance (EPR) analysis

ZnO nanoparticles were synthesized by solid coprecipitation method with consecutive high energy ball milling procedure. By reducing the particle size of ZnO to nano dimensions strong nano‐size effects were observed. In order to characterize the ZnO defect structure, EPR has been applied. It was observed that below 50 nm the surface defects play a dominant role in the electronic properties of ZnO. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

A finite size analysis of the structure factor in the antiferromagnetic Heisenberg (AFH) model

From a finite size analysis we extract the structure factorS(p, N=) of the one dimensional AFH-model in the groundstate: The gross structure is well described byL (p) = –ln(1– ^p ). The fine structure which only contributes a few percent reveals a pronounced non-linear behavior inL(p) with a maximum atp=0.20 and a minimum atp=0.82.     

Specific antibody response of mice after immunization with COS-7 cell derived avian influenza virus (H5N1) recombinant proteins

To develop avian influenza H5N1 recombinant protein, the hemagglutinin (HA), neuraminidase (NA), matrix (M), and non-structural (NS1) of avian influenza H5N1 isolates from Thailand were engineered to be expressed in prokaryotic (E. coli) and mammalian cell (COS-7) system. The plasmid pBAD-His and pSec-His were used as vectors for these inserted genes. Mice immunized with purified recombinant proteins at concentration 50–250 μg intramuscularly with Alum adjuvant at week 0, week 2, and week 3 showed a good immunogenicity measured by ELISA and neutralization assay. The HA and NS recombinant proteins produced in COS-7 cells can induce specific antibody titer detected by neutralization assay significantly higher than corresponding recombinant proteins produced in E. coli system. The antibody produced in immunized mice could neutralize heterologous avian influenza virus determined by micro-neutralization assay. This study shows that avian influenza virus H5N1 recombinant proteins produced in mammalian cell system were able to induce neutralizing antibody response.     

Experimental determination of Representative Volume Element (RVE) size in woven composites

A systematic approach is proposed to estimate the length scales of the representative volume element (RVE) in orthogonal plain woven composites. The approach is based on experimental full-field deformation measurements at mesoscopic scales. Stereovision digital image correlation (DIC) is conducted to determine the full-field strain distribution in on- and off-axis specimens loaded axially in tension. A sensitivity analysis is carried out to optimize the image correlation parameters. Using the optimized set of image correlation parameters, full-field strains are measured and used in conjunction with a simple strain averaging algorithm to identify the length scales at which globally applied and spatially-averaged local strains converge in values. The size of a virtual window containing local strain data, the average of which has the same value as the global strain, is identified as the RVE dimensions for the examined material. The smallest RVE sizes found in this work are shown to be both strain and angle dependent. The largest RVE dimension obtained is reported as a unique, strain and orientation insensitive RVE size for the woven composite examined.     

Prediction of drop-on-demand (DOD) pattern size in pulse voltage-applied electrohydrodynamic (EHD) jet printing of Ag colloid ink

Drop-on-demand printing is receiving a great deal of interest in industrial applications; however, the desired pattern sizes are realized by trial and error, through repeated printing experiments with varied materials (ink and suspended particles), operating conditions (voltage, flow rate, nozzle-to-plate distance, etc.), and substrate wettability. Since this approach requires a great deal of time, cost, and effort, a more convenient and efficient method that will predict pattern sizes with a minimal number of experiments is needed. In this study, we patterned a series of Ag dots and lines using a pulsed voltage-applied electrohydrodynamic jet printing system and measured their sizes with an optical microscope. We then applied a model suggested by Stringer and Derby (J Eur Ceram Soc 29:913–918, 2009) and Gao and Sonin (Proc R Soc Lond Ser A 444:533–554, 1994) to predict the pattern sizes, comparing these predictions with the measured sizes. Finally, we demonstrated our methodology on disconnected line repairing.     

Biodistribution and tumor uptake of C60(OH) x in mice

Radiolabeling of fullerol, ¹²⁵I–C₆₀(OH) _x , was performed by the traditional chloramine-T method. The C–I covalent bond in I–C₆₀(OH) _x was characterized by X-ray photoelectron spectroscopy (XPS) that was sufficiently stable for in vivo study. Laser light scattering spectroscopy clearly showed that C₆₀(OH) _x aggregated to large nanoparticle clumps with a wide range of distribution. The clumps formed were also visualized by transmission electron microscope (TEM). We examined the biodistribution and tumor uptake of C₆₀(OH) _x in five mouse bearing tumor models, including mouse H22 hepatocarcinoma, human lung giantcellcarcinoma PD, human colon cancer HCT-8, human gastric cancer MGC803, and human OS732 osteosarcoma. The accumulation ratios of ¹²⁵I–C₆₀(OH) _x in mouse H22 hepatocarcinoma to that in normal muscle tissue (T/N) and blood (T/B) at 1, 6, 24 and 72 h, reveal that ¹²⁵I–C₆₀(OH) _x gradually accumulates in H22 tumor, and retains for a quite long period (e.g., T/N 3.41, T/B 3.94 at 24 h). For the other four tumor models, the T/N ratio at 24 h ranges within 1.21–6.26, while the T/B ratio ranges between 1.23 and 4.73. The accumulation of C₆₀(OH) _x in tumor is mostly due to the enhanced permeability and retention effect (EPR) and the phagocytosis of mononuclear phagocytes. Hence, C₆₀(OH) _x might serve as a photosensitizer in the photodynamic therapy of some kinds of tumor.     

Nonpermuting limits (of zero-damping and infinite-system size) in an exactly solvable one-dimensional electrodynamical model

The quantum mechanics of an oscillating electron interacting with a one-dimensional electromagnetic string in the limit of zero damping (e → 0) and infinite field extension (Λ → ∞) depends on the order in which the limits are taken. If the limit e → 0 is taken after the limit Λ → ∞, one obtains gaussian wavefunctions for all stationary states (n = 0, 1, 2, …) of the particle. These gaussians do have the correct standard values for the variances 〈z²〉_n but otherwise obviously differ from the standard harmonic oscillator result. The latter arises only if the zero damping limit is taken before the infinite system limit.     

A delayed class of BOLD waveforms associated with spreading depression in the feline cerebral cortex can be detected and characterised using independent component analysis (ICA)

An application of independent component analysis to blood oxygenation level- dependent MRI (BOLD-MRI) results was used to detect cerebrovascular changes that followed the initiation of cortical spreading depression (CSD) in feline brain. The cortical images were obtained from a horizontal plane at 28 s intervals before, and for 1.4-1.75 h after, KCl dissolved in agar (KCl/agar) had been directly applied to the left suprasylvian gyrus of 13 anesthetized cats for 10 min. It successfully resolved, for the first time, a novel class of prolonged, and delayed, biphasic BOLD waveforms. These were larger in amplitude ( approximately 20%), longer lasting and more delayed in onset (13-33 min) than the brief propagating (90 s) BOLD increase ( approximately 4%) already known to be associated with CSD on earlier occasions. Furthermore, such changes occurred in localized regions on the hemisphere ipsilateral to the site of stimulus application in 4 out of 5 control subjects rather than themselves generating propagating waves. Finally, the biphasic waveforms were consistently abolished in the 4 experimental animals studied following the i.v. administration of sumatriptan (0.3 mg kg(-1)), an antimigraine 5-HT(1B/1D) agonist, 15 min before the application of the transient stimulus. They were abolished in 2 out of 4 animals following the intraperitoneal (i.p.) administration of SB-220453 (tonabersat: 10 mg kg(-1), 90 min before stimulus application), a novel anticonvulsant that has recently been reported to inhibit CSD. ICA has thus been successful in detecting a novel localized, as opposed to propagating, signal of potential physiological significance hidden in complex BOLD- MRI data, whose sensitivity to sumatriptan may relate it to the cerebrovascular changes reported in the headache phase of migraine.     

Enhancement of transport of curcumin to brain in mice by poly(n-butylcyanoacrylate) nanoparticle

Curcumin, a widely used coloring agent and spice in food, has a potential in blocking brain tumor formation and curing Alzheimer’s disease. Due to the specific properties of blood–brain barrier (BBB), only traces of curcumin were transported across BBB. The aim of the present study was to design and characterize curcumin loaded polybutylcyanoacrylate nanoparticles (PBCN) coated with polysorbate 80, and to evaluate the effect of PBCN as a delivery system on carrying curcumin across BBB. Curcumin loaded nanoparticles were prepared by an anionic polymerization method, and they presented in a core–shell spherical shape under transmission electron microscopy, with an average diameter of 152.0 nm. The average drug loading was 21.1%. Physicochemical status of curcumin in the nanoparticles was confirmed with differential scanning colorimetry and Fourier transform infrared spectroscopy. The in vitro release behavior of drug from the nanoparticles was fitted to a double phase kinetics model. The studies of pharmacokinetic and bio-distribution to brain were conducted in mice after intravenous administration of the nanoparticle formulation at the dose of 5 mg/kg and curcumin solution at the dose of 10 mg/kg via the tail vein. The results showed that in plasma, the area under concentration–time curve (AUC_0–∞) for curcumin loaded nanoparticles was greater than that for the control solution, moreover, the mean residence time of curcumin loaded nanoparticles was 14-fold that of the control solution. In brain, AUC_0–∞ for curcumin loaded nanoparticles was 2.53-fold that for the control solution. In conclusion, the present study demonstrated that PBCN could enhance the transport of curcumin to brain and have a potential as a delivery system to cross the BBB.     

A simple method for the determination of strains in epitaxial films: application to Eu(110) deposited on a Nb(110) buffer

In order to determine the strain tensor in a 375 nm thick Eu(110) epitaxial thin film, we have developed a new method, based on the accurate determination of the lattice vectors by high resolution X-ray diffraction. We show that a biaxial strain model gives a good representation of the state of the strains field in the film.     

Cavity size versus anion size in (TMTSF)2X salts: Possible implications for the uniqueness of (TMTSF)2C104

A simple, effective method for deducing the fit of the complex anion, X, within its structural cavity for (TMTSF)₂X salts with tetrahedral anions is presented. Subsequent analysis suggests that an electronic instability is operative over the full range of salts, becoming coincident with or leading to anion ordering and an insulating ground state above some critical fit of the anion within its structural cavity. Moreover, (TMTSF)₂C10₄ can be considered unique in that the perchlorate anion is too small for anion ordering to be the critical instability, yet large enough for anion ordering to occur at a finite temperature.     

A new aspect of size effect on the high-spin(5T2)-low-spin(1A1) transition in supported ferrous complexes

The temperature-dependent Mössbauer studies of carbon or MgO-supported Fe(ppi)₂(NCS)₂ show that the high-spin fraction f_hs vs wt% Fe loading plots obtained at 298 K and 78 K have a crossover point (we say the critical size) near 5 wt% Fe size (l0 size). For the SiO₂-supported Fe(2-pic)₃Cl₂.EtOH (pic=2-picolylamine), the room temperature Mössbauer spectra show that the high-spin fraction decreases steeply with decreasing iron-complex loading.     

Particle-number-conserving analysis of multiquasiparticle bands in ~(177)Lu

The experimental one-, three-, and five-quasiparticle bands in 177Lu are analyzed by the particle-number conserving (PNC) method for treating the cranked shell model with pairing interaction, in which the blocking effects are taken into account exactly. The experimental moments of inertia are reproduced very well by PNC calculations with us free parameter.     

Particle-number-conserving analysis of multiquasiparticle bands in ~(177)Lu

The experimental one-, three-, and five-quasiparticle bands in ~(177)Lu are analyzed by the particle-number conserving (PNC) method for treating the cranked shell model with pairing interaction, in which the blocking effects are taken into account exactly. The experimental moments of inertia are reproduced very well by PNC calculations with us free parameter.     

Role of the Metal/Semiconductor interface in quantum size effects: Pb /Si(111)

Self-organized islands of uniform heights can form at low temperatures on metal/semiconductor systems as a result of quantum size effects, i.e., the occupation of discrete electron energy levels in the film. We compare the growth mode on two different substrates [Si(111)- (7x7) vs Si(111)- Pb(sqrt[3]xsqrt[3] )] with spot profile analysis low-energy electron diffraction. For the same growth conditions (of coverage and temperature) 7-step islands are the most stable islands on the (7x7) phase, while 5-step (but larger islands) are the most stable islands on the (sqrt[3]xsqrt[3] ). A theoretical calculation suggests that the height selection on the two interfaces can be attributed to the amount of charge transfer at the interface.     

Classical size effects in the Raman scattering spectra of highly dispersed particles. Experimental studies (review)

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 49, No. 3, pp. 359–382, September, 1988.