Treatment of Bone Defects in Rabbit Tibiae using CaO-SiO(2)-P(2)O(5)-B(2)O(3) Bioactive Ceramics: Radiological, Biomechanical, and Histological Evaluation

Many calcium phosphate ceramics have been developed as bone graft Substitutes to treat bone defect. Bioactive glass ceramics have been improved in terms of mechanical strength and bioabsorbance. The purpose of this study was to compare bone binding capacity of hydroxyapatite and bioactive ceramics made by CaO-SiO(2)-P(2)O(5)-B(2)O(3)(Bonglass 6, 7). Bioactive ceramics(Bonglass 6, 7) or hydroxyapatite plates of 5 mm height were inserted to tibial bony defect of New Zealand white rabbits weighing 3-3.5 kg. Total number of rabbits was 36 and divided into 3 groups randomly. Bony binding and fusion capacity were evaluated through the radiological study every 2 weeks. 12 weeks after surgery gross examination, manual palpation, biomechanical and histological studies were made. Seven rabbits in all group died during breeding but in autopsy finding, there was no evidence suggesting infection or graft rejection. Fusion rates were 77.8%(7/9) in Bonglass 6 group, 80%(8/10) in Bonglass 7group, and 70%(7/10) in hydroxyapatite group. Mean values of the tensile strengths were 126.3 +/- 74.6 N in Bonglass 6 group, 136.6 +/- 77.2 N in Bonglass 7 group, and 135.6 +/- 113 N in hydroxyapatite group. In histological analysis of 2 specimens from each group, porous hydroxyapatite group showed slightly better bone binding capacity. Bonglass and hydroxyapatite group showed similar bone binding capacity and there was no statistically significant difference between 3 groups.Khang G, 2007, TISSUE ENG REGEN MED, V4, P441Asazuma T, 2005, J SPINAL DISORD TECH, V18, pS41Gosain AK, 2004, PLAST RECONSTR SURG, V114, P590, DOI 10.1097/01.PRS.0000128355.95900.DDLee Y, 2003, PHOTONIC NETW COMMUN, V6, P151LEE JH, 2003, J KOR ORTHOP ASS, V38, P612RYU HS, 2002, J KOR CERAMIC SOC, V39, P490BETS RR, 2002, ORTHOPAEDICS, V25, pS561Marchesi DG, 2000, EUR SPINE J, V9, P372Bauer TW, 2000, CLIN ORTHOP RELAT R, P10Ehrler DM, 2000, CLIN ORTHOP RELAT R, P38Hall EE, 1999, J PERIODONTOL, V70, P526JIRO T, 1997, CLIN ORTHOP RELAT R, V343, P183Emery SE, 1996, SPINE, V21, P2713BODEN SD, 1995, SPINE, V20, P412KIM YM, 1995, J KOREAN ORTHOP ASS, V30, P1099KOTANI S, 1992, CLIN ORTHOP RELAT R, P226KOKUBO T, 1987, J MATER SCI, V22, P4067HENCH LL, 1971, J BIOMED MATER RES S, V2, P117, DOI DOI 10.1002/JBM.820050611

Reduction of Lattice Thermal Conductivity in PbTe Induced by Artificially Generated Pores

Highly dense pore structure was generated by simple sequential routes using NaCl and PVA as porogens in conventional PbTe thermoelectric materials, and the effect of pores on thermal transport properties was investigated. Compared with the pristine PbTe, the lattice thermal conductivity values of pore-generated PbTe polycrystalline bulks were significantly reduced due to the enhanced phonon scattering by mismatched phonon modes in the presence of pores (200 nm–2 μm) in the PbTe matrix. We obtained extremely low lattice thermal conductivity (~0.56 W m−1 K−1 at 773 K) in pore-embedded PbTe bulk after sonication for the elimination of NaCl residue

Illuminating Recent Progress in Nanotransfer Printing: Core Principles, Emerging Applications, and Future Perspectives

Abstract As the demand for diverse nanostructures in physical/chemical devices continues to rise, the development of nanotransfer printing (nTP) technology is receiving significant attention due to its exceptional throughput and ease of use. Over the past decade, researchers have attempted to enhance the diversity of materials and substrates used in transfer processes as well as to improve the resolution, reliability, and scalability of nTP. Recent research on nTP has made continuous progress, particularly using the control of the interfacial adhesion force between the donor mold, target material, and receiver substrate, and numerous practical nTP methods with niche applications have been demonstrated. This review article offers a comprehensive analysis of the chronological advancements in nTP technology and categorizes recent strategies targeted for high‐yield and versatile printing based on controlling the relative adhesion force depending on interfacial layers. In detail, the advantages and challenges of various nTP approaches are discussed based on their working mechanisms, and several promising solutions to improve morphological/material diversity are presented. Furthermore, this review provides a summary of potential applications of nanostructured devices, along with perspectives on the outlook and remaining challenges, which are expected to facilitate the continued progress of nTP technology and to inspire future innovations

Hf-Doping Effect on the Thermoelectric Transport Properties of n-Type Cu0.01Bi2Te2.7Se0.3

Polycrystalline bulks of Hf-doped Cu0.01Bi2Te2.7Se0.3 are prepared via a conventional melt-solidification process and subsequent spark plasma sintering technology, and their thermoelectric performances are evaluated. To elucidate the effect of Hf-doping on the thermoelectric properties of n-type Cu0.01Bi2Te2.7Se0.3, electronic and thermal transport parameters are estimated from the measured data. An enlarged density-of-states effective mass (from ~0.92 m0 to ~1.24 m0) is obtained due to the band modification, and the power factor is improved by Hf-doping benefitting from the increase in carrier concentration while retaining carrier mobility. Additionally, lattice thermal conductivity is reduced due to the intensified point defect phonon scattering that originated from the mass difference between Bi and Hf. Resultantly, a peak thermoelectric figure of merit zT of 0.83 is obtained at 320 K for Cu0.01Bi1.925Hf0.075Te2.7Se0.3, which is a ~12% enhancement compared to that of the pristine Cu0.01Bi2Te2.7Se0.3

Anti-reflective porous Ge by open-circuit and lithography-free metal-assisted chemical etching

Porous Ge (PGe) layer is formed on single-crystalline Ge (c-Ge) as well as in a releasable form (e.g., free-standing PGe) by lithography-free metal-assisted chemical etching (MacEtch) at room temperature under open-circuit. A thin layer of Au is evaporated on the entire surface of c-Ge and Ge on insulator prior to immersion in an etching solution. It is found that an oxide-free interface between the surface and metal catalyst is vital to form uniform PGe layer. PGe layers with different morphologies and thicknesses are produced after various MacEtch times. In order to show the functionality of PGe, reflection spectra of c-Ge (i.e., before etching) and PGe layers are characterized at a wavelength range of 1000–1600 nm. The reflection of PGe is broadly reduced to 10%, which matches well with simulation results based on finite-difference-time-domain method. Among all the modeling factors, thickness of PGe layers is found to be the primary cause of the broadband reduction of the reflection. In addition, transfer-printable free-standing PGe layers are realized. The capability of the simple, clean, and lithography-free MacEtch to achieve PGe on rigid substrates as well as in a free-standing form holds significant potential in photonic and optoelectronic device applications.Ministry of Education (MOE)Submitted/Accepted versionThe work was supported by Ministry of Education, Singapore, under grant AcRF TIER 1-2018-T1-002-115 (RG 173/18). Simulation part was supported by Institute of Information & Communications Technology Planning & Evaluation (IITP) grant funded by the Korea government (MSIT) (No. 2020-0-00914, Development of hologram printing downsizing technology based on holographic optical element (HOE) and No. 2020-0-00109, Development of holographic lithography equipment and printing technology for security and books). X.L. acknowledges the US NSF DMR Award #1508140