Digital holographic microscopy with pure-optical spherical phase compensation

Telecentric architecture is proposed for circumventing, by the pure-optical method, the residual parabolic phase distortion inherent to standard configuration of digital holographic microscopy. This optical circumvention produces several important advantages. One is that there is no need for computer compensation of the parabolic phase during the phase map recovering procedure. The other is that in off-axis configuration, the spatial frequency useful domain is enlarged. The validity of the method is demonstrated by performing quantitative measurement of depth differences with high axial resolution.     

One-dimensional nanorod arrays: independent control of composition, length, and interparticle spacing with nanometer precision

We report the synthesis of solution dispersible, one-dimensional metal nanostructure arrays as small as 35 nm in diameter using on-wire lithography, wherein feature thickness and spacing in the arrays is tailorable down to approximately 6 and 1 nm, respectively. Using this unique level of control, we present solution-averaged extinction spectra of 35 nm diameter Au nanorod dimers with varying gap sizes to illustrate the effect of gap size on plasmon coupling between nanorods. Additionally, we demonstrate control over the composition of the arrays with Au, Ni, and Pt segments, representing important advances in controlling the ordering of sub-100 nm nanostructures that are not available with current synthesis or assembly methods.     

Community reinforcement approach plus vouchers among cocaine-dependent outpatients: Twelve-month outcomes.

The aims of this study were to assess the effectiveness of the Community Reinforcement Approach (CRA) plus vouchers treatment in a cohort of Spanish cocaine-dependent outpatients, and to examine the maintenance of treatment effects after the voucher intervention was discontinued. Sixty-four adult outpatients were randomly assigned to one of two treatment conditions, CRA plus vouchers or standard care. The vouchers program was implemented from weeks 1 to 24. Among patients assigned to the CRA plus vouchers condition, 65.5% completed 12 months of treatment versus 28.6% of those assigned to the standard care condition (p = .003). At the 12-month assessment, 58.6% of patients assigned to the CRA plus vouchers condition were abstinent, compared with 25.7% in the standard care condition (p = .008); furthermore, 34.5% of patients assigned to the CRA plus vouchers condition achieved twelve months of continuous cocaine abstinence, versus 17.1% in the standard care condition. Those treated in the CRA plus vouchers condition also achieved greater improvements in psychosocial functioning than those treated in the standard care condition. Overall, these results reveal an extension of the effectiveness of the CRA plus vouchers treatment to a community sample of cocaine-dependent outpatients, while also supporting the maintenance of treatment effects for 6 months after completion of the voucher program. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Superior hardness and Young's modulus of low temperature nanocrystalline diamond coatings

Nanocrystalline diamond (NCD) coatings with thickness of about 3 μm were grown on silicon substrates at four deposition temperatures ranging from 653 to 884 °C in CH₄/H₂/Ar microwave plasmas. The morphology, structure, chemical composition and mechanical and surface properties were studied by means of Atomic Force Microscopy (AFM), X-Ray Diffraction (XRD), Raman spectroscopy, nanoindentation and Water Contact Angle (WCA) techniques. The different deposition temperatures used enabled to modulate the chemical, structural and mechanical NCD properties, in particular the grain size and the shape. The characterization measurements revealed a relatively smooth surface morphology with a variable grain size, which affected the incorporated hydrogen amount and the sp² carbon content, and, as a consequence, the mechanical properties. Specifically, the hydrogen content decreased by increasing the grain size, whereas the sp² carbon content increased. The highest values of hardness (121 ± 25 GPa) and elastic modulus (1036 ± 163 GPa) were achieved in NCD film grown at the lowest value of deposition temperature, which favored the formation of elongated nanocrystallites characterized by improved hydrophobic surface properties.     

Single step fabrication of N-doped graphene/Si3N4/SiC heterostructures

In-plane heteroatom substitution of graphene is a promising strategy to modify its properties. The ability to dope graphene with electron-donor nitrogen heteroatoms is highly important for modulating electrical properties of graphene. Here we demonstrate a transfer-free method to directly grow large area quasi free-standing N-doped graphene bilayers on an insulating substrate （Si3N4）. Electron-bombardment heating under nitrogen flux results in simultaneous growth of N-doped graphene and a Si3N4 layer on the SiC surface. The decoupling of N-doped graphene from the substrate and the presence of Si3N4 are identified by X-ray photoemission spectroscopy and low-energy electron diffraction. The substitution of nitrogen atoms in the graphene planes was confirmed using high resolution X-ray photoemission spectroscopy which reveals several atomic configurations for the nitrogen atoms： Graphitic-like, pyridine-like, and pyrrolic- like. Furthermore, we demonstrated for the first time that N-doped graphene could be used to efficiently probe oxygen molecules via nitrogen atom defects.     

Inverted vs standard PTB7:PC70BM organic photovoltaic devices. The benefit of highly selective and extracting contacts in device performance

In this work we compare the photovoltaic performance of different cell designs, standard and inverted, for one of the most promising systems to achieve power conversion efficiencies over 10% in polymer:fullerene single cells, namely PTB7:PC70BM. Impedance spectroscopy, charge extraction and transient photovoltage are used in order to assign the electrical losses initially observed in the current density–voltage curve and understand the main limitation of every design. While inverted devices show competitive performance in terms of charge generation, transport of carriers and also for charge collection at electrodes, standard devices present additional resistive losses that are assigned to charge transfer issues at the active layer/anode interface. This additional resistance increase the overall series resistance of devices, lowers the fill factor and it is the ultimate responsible for the observed reduced device performance of standard cells in comparison to inverted ones. In this way, devices over 7.2% are reported with ZnO and MoO₃ as interlayer electrodes that act as improved highly selective and extracting contacts in comparison to standard PEDOT:PSS and Ca/Ag. Contacts are thus electrically optimized. Additional improvement of device performance must consider enhancement of intrinsic recombination properties of the blend. Lower molecular weights and/or any residual catalyst impurities with respect to other batches are the only limitation to reach record efficiencies as those shown in recent works.     

Biological control of Monilinia laxa and Rhizopus stolonifer in postharvest of stone fruit by Pantoea agglomerans EPS125 and putative mechanisms of antagonism

Treatment of stone fruits (apricot, peach and nectarine) with Pantoea agglomerans strain EPS125 decreased the incidence and diameter of lesions of brown rot caused by Monilinia laxa and soft rot caused by Rhizopus stolonifer. Root control was achieved on fruits either wounded and subsequently inoculated with the pathogens or non-wounded and naturally infected from orchards. The efficacy of biocontrol was dependent on the concentration of the biocontrol agent and pathogen. At medium to low pathogen dose, optimal EPS125 concentrations were above 10(7) CFU ml(-1). The median effective dose (ED(50)) of EPS125 was 4.5x10(4) in M. laxa and 2.2x10(5) CFU ml(-1) in R. stolonifer. However, EPS125 was more effective in M. laxa than in R. stolonifer as indicated by the ratio between ED(50) of the biocontrol agent and pathogen (K(z)/K(x)) which was 166 and 1263, respectively. Interactions between the strain EPS125 and the fruit surface, and M. laxa and R. stolonifer, were studied to determine the mechanisms of protection from postharvest rots. The strain EPS125 colonizes, grows and survives on stone fruit wounds. Significant inhibition of conidial germination and hyphal growth of R. stolonifer and M. laxa was achieved when the fungal and EPS125 cells were cocultivated on peel leachate or nectarine juice. However, no effect was observed when the antagonist and the pathogen cells were physically separated by a membrane filter which permits nutrient and metabolite interchange. Therefore, a direct interaction between the strain and the pathogen cells is necessary for antagonism, without a significant contribution of the production of antibiotic substances or nutrient competition. Preemptive exclusion by wound colonization and direct interaction with the pathogen is proposed as the mechanism of biocontrol.