Induced bone by calcium ohosphate (Ca-P) ceramics after 2-years implantation

The changes of induced bone with four kinds of Ca-P ceramics after 2 years implantation in the dorsal muscles of rabbits were investigated. After 2 years implantation, mature bone (with a lamellar structure after the remodeling process) with bone marrow was observed in HA1100 (HA, micro+macro porous), HA900 (HA, micro+macro porous) and BCP (HA/TCP=7:3, micro+ macro porous), and no bone formation was observed in HA1200 (HA, macro porous) ceramics. The induced bone neither disappeared nor grew uncontrollably, and was seen inside the pores of the implants or on the outer surface under the fibrous layer after 2 years. No bone formation was observed in the soft tissues distant from the implants. These results indicate that heterotopic bone formation induced by Ca-P materials did not give rise to uncontrolled growth over time, and the induced bone is limited to the inside or around the implants. Moreover, ectopic bone formation on the outer surface of the implants was detected in rabbits after 2 years.     

Experimental investigation on the effect of mixing length on the performance of two-phase ejector for CO2 refrigeration cycle with and without heat exchanger

In ejector system using the promising natural refrigerant CO₂, the mixing of high-speed two-phase primary flow and suction vapor is crucial in designing an efficient ejector. In this study, the effect of mixing length on ejector system performance was analyzed experimentally. The mixing lengths used were 5 mm, 15 mm, and 25 mm, with constant rectangular cross-section. The experiments were performed for both ejector and conventional expansion systems with and without internal heat exchanger (IHX) at different operating conditions. Based on the experimental results, mixing length had significant effect on entrainment ratio and on magnitude and profile of pressure recovery. The 5 mm and 15 mm types yielded the lowest and highest ejector efficiency and COP in all of the conditions used in this research, respectively. The use of IHX had net positive effect on system performance which verified the results of our previous study. A COP improvement of up to 26% over conventional system was obtained but improper sizing of mixing length lowered the COP by as much as 10%.     

Electronic Communication in the Mixed-valence States of Cyclobutadienecobalt Complexes having Two Ferrocenes and Two Anthraquinones

Two geometric isomers, Z and E forms of (η⁴-cyclobutadiene)(η⁵-cyclopentadienyl) cobalt simultaneously containing two ferrocene moieties and two anthraquinone moieties, 1 and 2, respectively, were synthesized, and their crystal structures were determined. These molecules formed double mixed-valence states caused by ferrocene–ferrocenium and anthraquinone–anthrasemiquinone electronic communications. In both 1 and 2, the thermodynamic stability of the mixed-valence state for the ferrocene moieties was higher than that of the anthraquinone moieties because of the orbital coupling of the CB–Co bridging unit. The comproportionation constant, K _c, for the ferrocene moieties was similar between 1 and 2, whereas the mixing coefficient, α, and the off-diagonal matrix-coupling element in the Marcus-Hush two-state model, H _AB, evaluated from analysis of the intervalence charge transfer (IVCT) band were larger for 1 than for 2. These results suggest the existence of higher electrostatic repulsion between two ferrocenium cations in 1 than in 2 and the occurrence of through-bond electronic communication. K _c for the anthraquinone moieties in the E form is smaller than that of the Z form, probably due to the through-space electronic interaction.     

Site-selective electroless nickel plating on patterned thin films of macromolecular metal complexes

We demonstrate a simple route to depositing nickel layer patterns using photocross-linked polymer thin films containing palladium catalysts, which can be used as adhesive interlayers for fabrication of nickel patterns on glass and plastic substrates. Electroless nickel patterns can be obtained in three steps: (i) the pattern formation of partially quaterized poly(vinyl pyridine) by UV irradiation, (ii) the formation of macromolecular metal complex with palladium, and (iii) the nickel metallization using electroless plating bath. Metallization is site-selective and allows for a high resolution. And the resulting nickel layered structure shows good adhesion with glass and plastic substrates. The direct patterning of metallic layers onto insulating substrates indicates a great potential for fabricating micro/nano devices.     

Organic–inorganic hybrid material as zwitterion: Synthesis and structure of terminal ammonium ions-containing organosilyl species supported on mono-lacunary Dawson polyoxometalate

The title compound 1 with a formula of (Bu₄N)₄[α₂-P₂W₁₇O₆₁{Me₃N⁺(CH₂)₃Si}₂O] · CH₃CN was obtained in 77.1% (4.21 g scale) yield by a 1:2 molar-ratio reaction of the mono-lacunary Dawson polyoxometalate (POM) [P₂W₁₇O₆₁]¹⁰⁻ with N-trimethoxysilylpropyl-N,N,N-trimethylammonium chloride ([Me₃N(CH₂)₃Si(OMe)₃]Cl) in mixed water/acetonitrile solution under acidic conditions and unequivocally characterized with complete elemental analysis, thermogravimetric and differential thermal analyses (TG/DTA), FTIR, solution (³¹P, ¹H, ¹³C and ²⁹Si) NMR and X-ray crystallography. Compound 1 contained two types of the ammonium cations, i.e., the counterions Bu₄N⁺ (free cations) and the terminal quaternary ammonium ions (bound cations) which are connected to the POM through the organosilyl groups.     

Effects of inner sleeves on the inner frictional resistance of open-ended piles driven into sand

In open-ended piles, inner friction is developed between inner pile shaft and the inner soil. Inner frictional resistance depends largely on the degree of soil plugging, which is influenced by many factors including pile diameter, relative density and end conditions of piles. In this paper, effects of inner sleeves on inner frictional resistance are discussed. The experiments were conducted on a medium-dense sandy ground using laboratory-scale piles. It was observed that the piles penetrated under partially-plugged or unplugged state. The results suggest that inner frictional resistance, Q_in increases with sleeve height, l linearly and requires 2D (D is pile outer diameter) of l to produce a large as 50% of Q_t by Q_in (Q_t is total resistance). The results also indicate that bearing capacity increases with wall thickness at the pile tip, which can be attributed to the increase in annular area. The results also indicate that soil plug height is independent of sleeve height. The results also reveal that the penetration of straight piles is closer to unplugged state than the sleeved piles. The results of incremental filling ratio and plug length ratio also indicate that the degree of soil plugging is affected by the sleeve height.     

Experimental cranioplasty and skeletal augmentation using an alpha-tricalcium phosphate/dicalcium phosphate dibasic/tetracalcium phosphate monoxide cement: a preliminary short-term experiment in rabbits

Calcium phosphate cement consisting of alpha-tricalcium phosphate (alpha-TCP), dicalcium phosphate dibasic (DCPD) and tetracalcium phosphate monoxide (TeCP) was implanted into surgically created full-thickness defects in the cranial bone (bone defect experiment) and directly onto the cranial bone under the periosteum (augmentation experiment). Three months after the implantation, the implants were retrieved with the surrounding tissues and studied histologically and micrographically to evaluate if the cement can be used as a cranioplasty and skeletal augmentation material. In the bone defect experiment, successful reconstruction of the defect was seen in 8 out of 12 specimens. Four specimens, where bleeding control was difficult at the time of implantation, showed partial loss of the cement. Histological and microradiographic studies of the successfully implanted cement revealed that new bone surrounded the implant nearly completely and united directly with the cement surface. In the augmentation experiment, the augmented area maintained the hemispherical shape and was connected tightly with the host bone. Histology and microradiography demonstrated that new bone formation was seen in the gap between the cement and the host bone, and on the outer surface (periosteum side) of the cement at the edge of the implant. From this preliminary short-term study, it could be concluded that the cement is a promising material for cranioplasty and skeletal augmentation with indications that it has good osteoconductivity.     

Calcium phosphate cement: in vitro and in vivo studies of the α-tricalcium phosphate-dicalcium phosphate dibasic-tetracalcium phosphate monoxide system

In this paper, calcium phosphate cement consisting of -tricalcium phosphate (-TCP), dicalcium phosphate dibasic (DCPD) and tetracalcium phosphate monoxide (TeCP) was investigated in vitro and in vivo. Measurements of compressive strength against soaking time in simulated body fluid (SBF) showed a rapid increase of the hardness for the first 7 days. The gained strength was retained up to 1 year and the maximal mean value was 94.7 (±14.4) MPa. X-ray diffraction (XRD) and scanning electron microscopy (SEM) presented precipitates of hydroxyapatite (HA) after mixing, also after soaking in SBF and after implantation in rat subcutaneous tissues. However, the conversion to HA happened in different ways between in vitro and in vivo exposures. Histologic examinations showed that the cement causes the same reactions at the interface with surrounding soft tissues as HA. The authors consider the cement to be a promising material as a bone substitute, bone cement or dental material, however, further studies in a paste form and in bone tissue environments are necessary.     

Microbolometer Terahertz Focal Plane Array and Camera with Improved Sensitivity in the Sub-Terahertz Region

Journal of Infrared, Millimeter, and Terahertz Waves - A pixel in an uncooled microbolometer terahertz (THz) focal plane array (FPA) has a suspended structure above read-out integrated circuit...     

Near-Infrared-Triggered On-Demand Controlled Release of Adeno-Associated Virus from Alginate Hydrogel Microbeads with Heat Transducer for Gene Therapy

Gene therapy using adeno-associated virus (AAV) has potential as a radical treatment modality for genetic diseases such as sensorineural deafness. To establish clinical applications, it is necessary to avoid immune response to AAV by controlled release system of AAV. Here, a near-infrared (NIR)-triggered on-demand AAV release system using alginate hydrogel microbeads with a heat transducer is proposed. By using a centrifuge-based microdroplet shooting device, the microbeads encapsulating AAV with Fe₃O₄ microparticles (Fe₃O₄-MPs) as a heat transducer are fabricated. Fe₃O₄-MPs generated heat by NIR enhanced the diffusion speed of the AAV, resulting in the AAV being released from the microbeads. By irradiating the microbeads encapsulating fluorescent polystyrene nanoparticles (FP-NPs) (viral model) with NIR, the fluorescence intensity decreased only for FP-NPs with a diameter of 20 nm and not for 100 or 200 nm, confirming that this system can release virus with a diameter of several tens of nanometers. By irradiating NIR to the AAV-encapsulating microbeads with Fe₃O₄-MPs, the AAV is released on demand, and gene transfection to cells by AAV is confirmed without loss of viral activity. The NIR-triggered AAV release system proposed in this study increases the number of alternatives for the method of drug release in gene therapy.