Chitosan adhesive for laser tissue repair: In vitro characterization

Background and Objectives Laser tissue repair usually relies on hemoderivate protein solders, based on serum albumin. These solders have intrinsic limitations that impair their widespread use, such as limited tensile strength of repaired tissue, poor solder solubility, and brittleness prior to laser denaturation. Furthermore, the required activation temperature of albumin solders (between 65 and 70°C) can induce significant thermal damage to tissue. In this study, we report on the design of a new polysaccharide adhesive for tissue repair that overcomes some of the shortcomings of traditional solders. Study Design/Materials and Methods Flexible and insoluble strips of chitosan adhesive (elastic modulus ~6.8 Mpa, surface area ~34 mm2, thickness ~20 µm) were bonded onto rectangular sections of sheep intestine using a diode laser (continuous mode, 120 ± 10 mW, = λ 808 nm) through a multimode optical fiber with an irradiance of ~15 W/cm2. The adhesive was based on chitosan and also included indocyanin green dye (IG). The temperature between tissue and adhesive was measured using a small thermocouple (diameter ~0.25 mm) during laser irradiation. The repaired tissue was tested for tensile strength by a calibrated tensiometer. Murine fibroblasts were cultured in extracted media from chitosan adhesive to assess cytotoxicity via cell growth inhibition in a 48 hours period. Results Chitosan adhesive successfully repaired intestine tissue, achieving a tensile strength of 14.7 ± 4.7 kPa (mean ± SD, n = 30) at a temperature of 60-65°C. Media extracted from chitosan adhesive showed negligible toxicity to fibroblast cells under the culture conditions examined here. Conclusion A novel chitosan-based adhesive has been developed, which is insoluble, flexible, and adheres firmly to tissue upon infrared laser activation.

Microstructural characterization of quenched melt-textured YBa2Cu3O7-δ materials

The microstructure of YBa2Cu3O7-δ (YBCO) materials, melt-textured in air and quenched from the temperature range 900-990°C, has been characterized using a combination of x-ray diffractometry, optical microscopy, scanning electron microscopy, transmission electron microscopy, and energy dispersive x-ray spectrometry. BaCu2O2 and BaCuO2 were found to coexist in samples quenched from the temperature range 920-960°C. The formation of BaCu2O2 preceded the formation of YBCO. Once the YBCO had formed, BaCu2O2 was present at the solidification front filling the space between nearly parallel platelets of YBCO. Large Y2BaCuO5 particles at the solidification front appeared divided into smaller ones as a result of their dissolution in the liquid that quenched as BaCu2O2.

Preparation and characterization of tin oxide nanowires on SiC

Interest in nanowires of metal oxide oxides has been exponentially growing in the last years, due to the attracting potential of application in electronic, optical and sensor field. We have focused our attention on the sensing properties of semiconducting nanowires as conductometric and optical gas sensors. Single crystal tin dioxide nanostructures were synthesized to explore and study their capability in form of multi-nanowires sensors. The nanowires of SnO2 have been used to produce a novel gas sensor based on Pt/oxide/SiC structure and operating as Schottky diode. For the first time, a reactive oxide layer in this device has been replaced by SnO2 nanowires. Proposed sensor has maintained the advantageous properties of known SiC- based MOS devices, that can be employed for the monitoring of gases (hydrogen and hydrocarbons) emitted by industrial combustion processes.

Microwave synthesis and spectroscopic characterization of manganese oxalate nanocrystals

The microwave synthesis of MnC2O4·2H2O nanoparticles was performed through the thermal double decomposition of oxalic acid dihydrate (C2H2O4·2H2O) and Mn(OAc)2·4H2O solutions using a CATA-2R microwave reactor. Structural characterization was performed using X-ray diffraction (XRD), particle size and shape were analyzed using transmission electron microscopy (TEM). The chemical in the structures was investigated using electron paramagnetic resonance (EPR) as well as optical absorption spectra and near-infrared (NIR) spectroscopies. The nanocrystals produced with this method were pure and had a distorted rhombic octahedral structure.

Spectroscopic characterization of manganese minerals

Manganese minerals ardenite, alleghanyite and leucopoenicite originated from Madhya Pradesh, India, Nagano prefecture Japan, Sussex Country and Parker Shaft Franklin, Sussex Country, New Jersey respectively are used in the present work. In these minerals manganese is the major constituent and iron if present is in traces only. An EPR study of on all of the above samples confirms the presence of Mn(II) with g around 2.0. Optical absorption spectrum of the mineral alleghanyite indicates that Mn(II) is present in two different octahedral sites and in leucophoenicite Mn(II) is also in octahedral geometry. Ardenite mineral gives only a few Mn(II) bands. NIR results of the minerals ardenite, leucophoenicite and alleghanyite are due to hydroxyl and silicate anions which confirming the formulae of the minerals.

Numerical characterization of the mechanical properties of metal nanowires

Nanowires (NWs) have attracted appealing and broad application owing to their remarkable mechanical, optical, electrical, thermal and other properties. To unlock the revolutionary characteristics of NWs, a considerable body of experimental and theoretical work has been conducted. However, due to the extremely small dimensions of NWs, the application and manipulation of the in situ experiments involve inherent complexities and huge challenges. For the same reason, the presence of defects appears as one of the most dominant factors in determining their properties. Hence, based on the experiments' deficiency and the necessity of investigating different defects' influence, the numerical simulation or modelling becomes increasingly important in the area of characterizing the properties of NWs. It has been noted that, despite the number of numerical studies of NWs, significant work still lies ahead in terms of problem formulation, interpretation of results, identification and delineation of deformation mechanisms, and constitutive characterization of behaviour. Therefore, the primary aim of this study was to characterize both perfect and defected metal NWs. Large-scale molecular dynamics (MD) simulations were utilized to assess the mechanical properties and deformation mechanisms of different NWs under diverse loading conditions including tension, compression, bending, vibration and torsion. The target samples include different FCC metal NWs (e.g., Cu, Ag, Au NWs), which were either in a perfect crystal structure or constructed with different defects (e.g. pre-existing surface/internal defects, grain/twin boundaries). It has been found from the tensile deformation that Young's modulus was insensitive to different styles of pre-existing defects, whereas the yield strength showed considerable reduction. The deformation mechanisms were found to be greatly influenced by the presence of defects, i.e., different defects acted in the role of dislocation sources, and many affluent deformation mechanisms had been triggered. Similar conclusions were also obtained from the compressive deformation, i.e., Young's modulus was insensitive to different defects, but the critical stress showed evident reduction. Results from the bending deformation revealed that the current modified beam models with the considerations of surface effect, or both surface effect and axial extension effect were still experiencing certain inaccuracy, especially for the NW with ultra small cross-sectional size. Additionally, the flexural rigidity of the NW was found to be insensitive to different pre-existing defects, while the yield strength showed an evident decrease. For the resonance study, the first-order natural frequency of the NW with pre-existing surface defects was almost the same as that from the perfect NW, whereas a lower first-order natural frequency and a significantly degraded quality factor was observed for NWs with grain boundaries. Most importantly, the <110> FCC NWs were found to exhibit a novel beat phenomenon driven by a single actuation, which was resulted from the asymmetry in the lattice spacing in the (110) plane of the NW cross-section, and expected to exert crucial impacts on the in situ nanomechanical measurements. In particular, <110> Ag NWs with rhombic, truncated rhombic, and triangular cross-sections were found to naturally possess two first-mode natural frequencies, which were envisioned with applications in NEMS that could operate in a non-planar regime. The torsion results revealed that the torsional rigidity of the NW was insensitive to the presence of pre-existing defects and twin boundaries, but received evident reduction due to grain boundaries. Meanwhile, the critical angle decreased considerably for defected NWs. This study has provided a comprehensive and deep investigation on the mechanical properties and deformation mechanisms of perfect and defected NWs, which will greatly extend and enhance the existing knowledge and understanding of the properties/performance of NWs, and eventually benefit the realization of their full potential applications. All delineated MD models and theoretical analysis techniques that were established for the target NWs in this research are also applicable to future studies on other kinds of NWs. It has been suggested that MD simulation is an effective and excellent tool, not only for the characterization of the properties of NWs, but also for the prediction of novel or unexpected properties.

Synthesis and spectroscopic characterization of magnesium oxalate nano-crystals

Synthesis of MgC2O4⋅2H2O nano particles was carried out by thermal double decomposition of solutions of oxalic acid dihydrate (C2H2O4⋅2H2O) and Mg(OAc)2⋅4H2O employing CATA-2R microwave reactor. Structural elucidation was carried out by employing X-ray diffraction (XRD), particle size and shape were studied by transmission electron microscopy (TEM) and nature of bonding was investigated by optical absorption and near-infrared (NIR) spectral studies. The powder resulting from this method is pure and possesses distorted rhombic octahedral structure. The synthesized nano rod is 80 nm in diameter and 549 nm in length.

Synthesis, characterization and comparative OFET behaviour of indenofluorene-bithiophene and terthiophene alternating copolymers

The synthesis of alternating copolymers of tetraalkylindenofluorene with bithiophene and terthiophene using Suzuki polycondensation route is reported. We report on the optical and electrochemical properties of these copolymers. AFM analysis of the microscopic morphology of thin deposits showed that the copolymer with terthiophene units produced the more ordered films, with well-defined fibrillar structures, resulting from highly-regular dense packing due to strong π-π interchain interactions, in contrast to the amorphous bithiophene copolymer. Upon testing these materials in FETs the terthienyl copolymers displayed the higher charge mobilities among the studied compounds, with values of over 10-4 cm2 V-1 s-1 being obtained.

Synthesis, characterization and comparative study of thiophene- benzothiadiazole based donor-acceptor-donor (D-A-D) materials

The synthesis and characterization of solution processable donor-acceptor-donor (D-A-D) based conjugated molecules with varying ratios of thiophene as donor (D) and benzothiadiazole as acceptor (A) are reported. Optical, electrochemical, thermal, morphological and organic thin film transistor (OTFT) device properties of these materials were investigated. The thermal and polarized optical microscope analysis indicates that the materials having higher D/A ratios exhibit both liquid crystalline (LC) and OTFT behavior. AFM analysis of the materials having D/A ratios of 3 and 4 (3T1B and 4T1B) show well ordered structures, resulting from strong π-π interchain interactions compared to the other molecules in this study. A XRD patterns for 3T1B and 4T1B thin films also shows high crystalline ordering. Solution processed OTFTs of 3T1B and 4T1B have shown un-optimized charge carrier mobilities of 2 × 10 -2 cm 2 V -1 s -1 and 4 × 10 -3 cm 2 V -1 s -1, respectively on bare Si/SiO 2 substrate.

Furan containing diketopyrrolopyrrole copolymers : synthesis, characterization, organic field effect transistor performance and photovoltaic properties

In this work, we report design, synthesis and characterization of solution processable low band gap polymer semiconductors, poly{3,6-difuran-2-yl-2,5-di(2- octyldodecyl)-pyrrolo[3,4-c]pyrrole-1,4-dione-alt-phenylene} (PDPP-FPF), poly{3,6-difuran-2-yl-2,5-di(2-octyldodecyl)-pyrrolo[3,4-c]pyrrole-1, 4-dione-alt-naphthalene} (PDPP-FNF) and poly{3,6-difuran-2-yl-2,5-di(2- octyldodecyl)-pyrrolo[3,4-c]pyrrole-1,4-dione-alt-anthracene} (PDPP-FAF) using the furan-containing 3,6-di(furan-2-yl)pyrrolo[3,4-c]pyrrole-1,4(2H,5H)-dione (DBF) building block. As DBF acts as an acceptor moiety, a series of donor-acceptor (D-A) copolymers can be generated when it is attached alternatively with phenylene, naphthalene or anthracene donor comonomer blocks. Optical and electrochemical characterization of thin films of these polymers reveals band gaps in the range of 1.55-1.64 eV. These polymers exhibit excellent hole mobility when used as the active layer in organic thin-film transistor (OTFT) devices. Among the series, the highest hole mobility of 0.11 cm 2 V -1 s -1 is achieved in bottom gate and top-contact OTFT devices using PDPP-FNF. When these polymers are used as a donor and [70]PCBM as the acceptor in organic photovoltaic (OPV) devices, power conversion efficiencies (PCE) of 2.5 and 2.6% are obtained for PDPP-FAF and PDPP-FNF polymers, respectively. Such mobility values in OTFTs and performance in OPV make furan-containing DBF a very promising block for designing new polymer semiconductors for a wide range of organic electronic applications.

Sol-gel synthesis and characterization of cubic bismuth zinc niobium oxide nanopowders

Bismuth zinc niobium oxide (BZN) was successfully synthesized by a diol-based sol-gel reaction utilizing metal acetate and alkoxide precursors. Thermal analysis of a liquid suspension of precursors suggests that the majority of organic precursors decompose at temperatures up to 150°C, and organic free powders form above 350°C. The experimental results indicate that a homogeneous gel is obtained at about 200°C and then converts to a mixture of intermediate oxides at 350–400°C. Finally, single-phased BZN powders are obtained between 500 and 900°C. The degree of chemical homogeneity as determined by X-ray diffraction and EDS mapping is consistent throughout the samples. Elemental analysis indicates that the atomic ratio of metals closely matches a Bi1.5ZnNb1.5O7 composition. Crystallite sizes of the BZN powders calculated from the Scherrer equation are about 33–98 nm for the samples prepared at 500–700°C, respectively. The particle and crystallite sizes increase with increased sintering temperature. The estimated band gap of the BZN nanopowders from optical analysis is about 2.60–2.75 eV at 500-600°C. The observed phase formations and measured results in this study were compared with those of previous reports.

Pyrene based conjugated materials: synthesis, characterization and electroluminescent properties

In this work, three novel pyrene cored small conjugated molecules, namely 1,3,6,8-tetrakis(6-(octyloxy)naphthalene-2-yl)pyrene (PY-1), 1,3,6,8-tetrakis((E)-2-(6-(n-octyloxy)naphthalene-2-yl)vinyl)pyrene (PY-2) and 1,3,6,8-tetrakis((6-(n-octyloxy)naphthalene-2-yl)ethynyl)pyrene (PY-3) have been synthesized by Suzuki, heck and Sonogashira organometallic coupling reactions, respectively. The effects of single, double and triple bonds on their optical, electrochemical, and thermal properties are studied in detail. These are all materials fluorescent and they have been used in organic light-emitting diodes (OLEDs) and their electroluminescent properties have been studied.

Synthesis, characterization, and electronic structure studies of cubic Bi1.5ZnTa1.5O7 for photocatalytic applications

Bi1.5ZnTa1.5O7 (BZT) has been synthesized using an alkoxide based sol-gel reaction route. The evolution of the phases produced from the alkoxide precursors and their properties have been characterized as function of temperature using a combination of thermogravimetric analysis (TGA) coupled with mass spectrometry (MS), infrared emission spectrometry (IES), X-ray diffraction (XRD), ultraviolet and visible (UV-Vis) spectroscopy, Raman spectroscopy, and N2 adsorption/desorption isotherms. The lowest sintering temperature (600∘C) to obtain phase pure BZT powders with high surface area (14.5m2/g) has been determined from the thermal decomposition and phase analyses.The photocatalytic activity of the BZT powders has been tested for the decolorization of organic azo-dye and found to be photoactive under UV irradiation.The electronic band structure of the BZT has been investigated using density functional theory (DFT) calculations to determine the band gap energy (3.12 eV) and to compare it with experimental band gap (3.02 eV at 800∘C) from optical absorptionmeasurements. An excellent match is obtained for an assumption of Zn cation substitutions at specifically ordered sites in the BZT structure.

Fabrication and characterization of polyterpenol as an insulating layer and incorporated organic field effect transistor

A non-synthetic polymer material, polyterpenol, was fabricated using a dry polymerization process namely RF plasma polymerization from an environmentally friendly monomer and its surface, optical and electrical properties investigated. Polyterpenol films were found to be transparent over the visible wavelength range, with a smooth surface with an average roughness of less than 0.4 nm and hardness of 0.4 GPa. The dielectric constant of 3.4 for polyterpenol was higher than that of the conventional polymer materials used in the organic electronic devices. The non-synthetic polymer material was then implemented as a surface modification of the gate insulator in field effect transistor (OFET) and the properties of the device were examined. In comparison to the similar device without the polymer insulating layer, the polyterpenol based OFET device showed significant improvements. The addition of the polyterpenol interlayer in the OFET shifted the threshold voltage significantly; + 20 V to -3 V. The presence of trapped charge was not observed in the polyterpenol interlayer. This assisted in the improvement of effective mobility from 0.012 to 0.021 cm 2/Vs. The switching property of the polyterpenol based OFET was also improved; 107 compared to 104. The results showed that the non-synthetic polyterpenol polymer film is a promising candidate of insulators in electronic devices.

Fabrication and characterization of RF plasma polymerized thin films from 3,7-dimethyl-1,6-octadien-3-ol for electronic and biomaterial applications

Poly(linalool) thin films were fabricated using RF plasma polymerisation. All films were found to be smooth, defect-free surfaces with average roughness of 0.44 nm. The FTIR analysis of the polymer showed a notable reduction in –OH moiety and complete dissociation of C=C unsaturation compared to the monomer, and presence of a ketone band absent from the spectrum of the monomer. Poly(linalool) were characterised by chain branching and a large quantity of short polymer chains. Films were optically transparent, with refractive index and extinction coefficient of 1.55 and 0.001 (at 500 nm) respectively, indicating a potential application as an encapsulating (protective) coating for circuit boards. The optical band gap was calculated to be 2.82 eV, which is in the semiconducting energy gap region.