Wettability of the morphologically and compositionally varied surfaces prepared from blends of well ordered comb-like polymer and polystyrene

Phase-separated surfaces of blends of polystyrene (PS) and well ordered comb-like polymer, poly[(oxy(decylsulfonylmethyl)ethylene)] (CH(3)-10SE), were prepared by spin casting polymer mixtures. Various surface morphologies, such as holes, islands, connected islands and pillars, were prepared by changing the blend compositions. Due to the influence of the CH(3)-10SE domain with a well ordered molecular conformation, a very low energy surface (≈22mN/m) was created, which is close to the value of the pure polymer (≈20mN/m), even when the blends contained only 20wt.% of the pure polymer. Furthermore, by selective etching the PS domain in the blend surfaces, the advancing contact angles of water and n-hexadecane were highly increased from 113.5° and 43.2° for the pure CH(3)-10SE surface to 133.3° and 67.2° for the CH(3)-10SE structural surfaces with holes prepared using the solvent etching method, respectively. The result of the water advancing contact angles measured on the samples immersed in water over 20days showed that the film stability of CH(3)-10SE could be improved considerably by even adding small amounts of PS.     

Reference-free impedance-based crack detection in plates

Impedance-based damage detection techniques gained popularity among structural health monitoring (SHM) and nondestructive testing (NDT) communities due to their sensitivity to local damage and applicability to complex structures. In general, conventional impedance-based techniques identify damage by comparing “current” impedance signals with “baseline” ones obtained from the pristine condition of a structure. However, in-situ structures are often subject to changing temperature and loading conditions that can adversely affect measured impedance signals and cause false-alarms. In this paper, a “reference-free” impedance method, which does not require direct comparison of the current impedance signals with the previously obtained baseline impedance signals, is developed for crack detection in a plate-like structure. The proposed technique utilizes a single pair of PZTs collocated on the opposite surfaces of a structure to extract mode conversion produced by crack formation. Then, a reference-free damage classifier is developed and performed on the extracted mode conversion for instantaneous damage diagnosis. Numerical simulations and experimental tests have been conducted explicitly considering varying temperature and loading conditions to demonstrate the robustness of the proposed damage detection technique under varying operational and environmental conditions.     

Fabrication of uniform nanogrooves on 6H-SiC by femtosecond laser ablation

The fabrication of parallel deep nanogrooves on 6H-SiC by femtosecond laser ablation (λ=785 nm) is reported. The periodicity of the nanogrooves was measured to be about 200±20 nm and the depth exceeded 15 μm. The nanogrooves have high uniformity in size and pattern over the entire depth. Laser fluence is found to be the critical parameter to obtain these deep and regular nanogrooves. The feasibility for large area fabrication of nanogrooves by femtosecond laser ablation is demonstrated.     

Simultaneous tracer diffusion and interdiffusion in a sandwich-type configuration to provide the composition dependence of the tracer diffusion coefficients

In this paper, a new formalism of a combined tracer and interdiffusion experiment for a binary interdiffusion couple is developed. The analysis requires an interdiffusion couple that initially contains a thin layer of tracers of one or both of the constituent elements at the original interface of the couple (sandwich interdiffusion experiment). This type of interdiffusion experiment was first performed in 1958 by J.R. Manning. The theoretical analysis presented in this paper is based on a newly developed phenomenological theory of isotopic interdiffusion combined with the Boltzmann–Matano formalism. This new analysis now provides the means to obtain the composition dependent interdiffusion coefficient and tracer diffusion coefficients simultaneously from analysis of the interdiffusion and tracer profiles in a single sandwich interdiffusion experiment. The new analysis is successfully applied to the results of Manning’s original ‘sandwich interdiffusion’ experiment in the Ag–Cd system (six couples in total) and is validated with an independent determination of the Ag and Cd tracer diffusion coefficients by Schoen using the conventional thin film technique. Suggestions for further development of the sandwich interdiffusion experiment and analysis to the case of multicomponent alloys are provided.     

Pattern recognition for evaluator errors in a credit scoring model for technology-based SMEs

A credit scoring model for technology-based small and medium enterprises presupposes evaluator objectivity and evaluation consistency; however, there is always some amount of error in any technology evaluation. This can be due in part to the subjective evaluation attributes that comprise part of the credit scoring model. The evaluated values of subjective attributes can vary among evaluators. In this study, we identified the significant characteristics of both evaluator and evaluation teams in terms of evaluation error using a decision tree analysis. Our results can improve the accuracy of a wide range of evaluation procedures for technology financing.     

Biocompatibility of a PDMS-coated micro-device: Bladder volume monitoring sensor

We evaluated the biocompatibility of a dimethylpolysiloxane-coated micro-device which had been designed for monitoring real-time bladder volume in previous studies.The extract assay with dimethylpolysiloxane which had been used for coating the micro-device to measure the bladder volume was performed as an in vitro cytotoxicity test.For in vivo biocompatibility testing,the inflammatory responses around the implantation site of the micro-device in subcutaneous tissue of rat were assessed by light microscope with H&E stain and fluorescence microscope with ED1 stain and von Willebrand factor stain.The averages of cell viability in dimethylpolysiloxane group were 84.6%and 82.3%at 24 h and 72 h incubation, respectively.The qualitative evaluations with light and fluorescence microscope revealed that the inflammatory changes peaked during 2 weeks but almost disappeared at 4 weeks after implantation of devices.The quantitative evaluations for granulation layer formation and neovascularization showed that the thickness of the layer in dimethylpolysiloxane group peaked during 2 weeks but it came to be stabilized at 4 weeks as thin as at 2 weeks in control group,and the frequency of neovascularization was higher in dimethylpolysiloxane group than in control group but it was not increased with time.The dimethylpolysiloxane-coated micro-device is thought be a reliable bio-medical device.     

Facile synthesis of near-infrared CuInS<Subscript>2</Subscript>/ZnS quantum dots and glycol-chitosan coating for in vivo imaging

This study describes the synthesis method of water-soluble, low-toxicity, photostable highly luminescent probes based on I–III–VI₂ type semiconductor quantum dots (QDs) and the possibility of tumor targeting in living animals. Cd-free high-quality CuInS₂/ZnS core/shell QDs were synthesized, and their surfaces were reacted with mercaptoundecanoic acid for aqueous phase transfer followed by reaction with glycol-chitosan; lastly, Arg-Gly-Asp (RGD) integrin-binding peptide was covalently attached for in vivo tumor targeting. Dowtherm A, a highly viscous heat-transfer organic fluid, was used to control semiconductor crystal growth at high temperature (>230 °C) during organic synthesis. The structural and optical properties of the resulting CuInS₂/ZnS QDs were investigated. The average diameters of CuInS₂ and CuInS₂/ZnS QDs were 3.0 and 3.7 nm, respectively. Cell toxicity and in vivo tumor targetability in RR1022 cancer cell-xenografted mice were further evaluated using cRGDyk-tagged glycol-chitosan-coated CuInS₂/ZnS QDs. Glycol-chitosan-coated MUA-QDs displayed a Z-average diameter of 203.8 ± 7.67 nm in water by dynamic light scattering.

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Graphical abstract In vivo tumor targeting using cRGDyk-tagged glycol-chitosan-coated MUA-CuInS₂/ZnS QDs nanoparticles

     

Flexibility of inorganic tennis ball structures inducing anion selectivity

Inorganic tennis balls (ITBs), [[{Pt(betmp)(dach)}(2)Cu](2)(X)][X](3) (in which X=ClO(4) (-) (3), NO(3) (-) (4), Cl(-) (5) and Br(-) (6); dach=trans-1,2-diaminocyclohexane and betmp=bisethylthiomethylidenepropanedioate) and [[{Pt(dteym)(dach)}(2)Cu](2)(PF(6))][PF(6)](3) (7; dteym=1,3-dithiepane-2-ylidenemalonate), were prepared as crystals. Investigation of their X-ray crystal structures revealed that shapes of the cavities in ITBs show significant distortions that depend on the properties of the encapsulated anions. The CuCu* distance was observed to be longest in 7 and shortest in 5, the difference between them being 2.05 A. The flexibility of cavity structures of ITBs makes it possible to encapsulate various anions inside the cavity, while their distortions may be a reason for the difference in the encapsulating ability for anions, that is, anion selectivity. Especially, the distortions observed in 7 are so severe that the encapsulating ability of the cavity for PF(6) (-) is very low compared to other anions. The shapes of ITBs with ClO(4) (-) and BF(4) (-) ions inside their cavities are very similar; however, ClO(4) (-) is encapsulated by the cavity better than BF(4) (-), which is explicable by the difference of metal-anion interactions. This structural study on ITBs gives a clue to the origin of the anion selectivity of the cavity in ITBs previously investigated by (19)F NMR spectroscopy of the ITBs in methanol.     

Storage allocation under processor sharing I: exact solutions and asymptotics

We consider a processor-sharing storage allocation model, which has m primary holding spaces and infinitely many secondary ones, and a single processor servicing the stored items (customers). An arriving customer takes a primary space, if one is available. We define the traffic intensity ρ to be λ/μ where λ is the customers’ arrival rate and μ is the service rate of the processor. We study the joint probability distribution of the numbers of occupied primary and secondary spaces. For 0<ρ<1, we obtain the exact solutions for m=1 and m=2. For arbitrary m we study the problem in the asymptotic limit ρ↑1 with m fixed. We also give the tail of the distribution for a fixed ρ<1 and any m.