Bioactivity and cytocompatibility of dicalcium phosphate/poly (amino acid) biocomposite with degradability

A bioactive composite of dicalcium phosphate (DCP) and poly (amino acid) (PAA) was fabricated, and the in vitro bioactivity, degradability, and cellular responses to the DCP/PAA composite (DPC) were investigated as compared to PAA. Apatite formation on DPC surfaces occurred after immersion into simulated body fluid (SBF) for 7 days, but not on the surface of PAA. The weight loss ratio of DPC could reach 18.6 ± 0.3 wt% after soaking into phosphate buffered saline (PBS) for 2 months, which was higher than PAA (11.0 ± 0.2 wt%). Cell attachment and proliferation of MG-63 cells on DPC was obviously higher than on PAA. Moreover, the cells spread and formed confluent layer on the DPC surfaces. The alkaline phosphatase activity (ALP) of the cells on DPC was significantly greater than PAA at day 5 and day 7. The results suggested that introducing DCP into PAA makes the composite bioactive and more degradable, and meanwhile enhances osteoblast-like cells attach, proliferation and osteogenic differentiation.     

Influence of Rhodamine (B) doping on vibrational,morphological and absorption properties of poly(vinyl) alcohol

Contribution of Rhodamine B doping on the structural and optical properties of PVA is investigated here. With increasing doping wt%, Raman spectra show the disappearance of main PVA peaks revealing a decrease in crystallinity and breaking of bonds, which also results in modified surface morphology as seen from corresponding SEM measurements. Optical absorption measurements show the possibility of both direct and indirect transitions, also indicating strong modifications in optical properties as a result of doping fluorescent dye in the polymer host.     

套管井中仪器偏心对井壁超声电视图象的影响及其校正

文章研究了在套管井中仪器偏心对井壁超声电视图象的影响,提出了基于计算影响所用模型的校正方向,实验结果表明,该方法能较好地消除由于仪器偏心所引起的超声电视图象中的两条垂直黑带,明显地改善图象的质量,经对比度增强后,井壁的细节更加清楚。     

Surface modification of hydroxyapatite with poly(methyl methacrylate) via surface-initiated ATRP

This article describes the fabrication of hydroxyapatite (HAP) nanocomposites grafted with poly(methyl methacrylate) (PMMA). Surface-initiated atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) was carried out from hydroxyapatite particles derivatized with ATRP initiators. The structure and properties of the nanocomposites were investigated by thermogravimetric analysis (TGA), transmission electron microscopy (TEM), differential scanning calorimeter (DSC) measurements, and contact angle analyses. TGA was used to estimate the grafting density of ATRP initiators (0.49 initiator/nm²) and the amount of grafted PMMA on the HAP surface. The contact angle analyses indicated that grafting PMMA onto the HAP surface dramatically increased the hydrophobicity of the surface. Moreover, the HAP nanocomposites showed excellent dispersibility in both aqueous solution and organic solvent.     

Influence of laser irradiation on the optical and structural properties of poly(ethylene terephthalate) fibres

Laser irradiation has been previously investigated for achieving uniform heating of polyethylene terephthalate (PET) fibres in the hot-drawing stage of the production process, so as to obtain better fibre mechanical properties. The optical properties and dye uptake of PET fibres also depend on the polymer chain orientation and crystallinity within the fibre structure. This paper reports an investigation of a concept whereby laser irradiation and interferometry could be used to modify and trace a small change in the optical properties of a PET monofilament fibre, but the corresponding change in the dye uptake would not be detected visually. A copper vapour laser (550-580 nm wavelengths) was used to expose consecutive 4 mm lengths along a running length of monofilament to 39.8 W cm⁻², at a pulse rate of 9.89 kHz in order to modify, in a controlled way, the polymer crystallinity and orientation. A 3D finite element simulation, based on uncoupled heat-transfer analysis, indicated that rapid heating and cooling could be obtained with the laser to give the small changes required. Irradiated and untreated samples were analysed by interferometry and a 0.16% change was detected in the birefringence profiles, corresponding to a small reduction in the degree of orientation and crystallinity of the irradiated samples. Density measurements and wide-angle X-ray scattering (WAXS) analysis confirmed the change in crystallinity. Tests conducted for dye adsorption and tensile strength showed a small increase in the former and only a very small decrease in the latter. It was concluded that these changes in property provide the opportunity for a laser-irradiated PET monofilament fibre to be used as a subtle tracer element in brand labels for textile garments as an anti-counterfeit measure.     

Effect of molecular weight on the ultrasonic degradation of poly(vinyl-pyrrolidone)

The ultrasonic degradation of poly(vinyl-pyrrolidone) (PVP) of different initial molecular weights was studied at a fixed temperature. The effect of solution concentration on the rate of degradation was investigated. A method of viscometry was used to study the degradation behavior and kinetic model was developed to estimate the degradation rate constant. The results were indicated that the rate of ultrasonic degradation increased with increasing molecular weight. It was found that rate constant decreases as the concentration increases. The calculated rate constants correlated in terms of inverse concentration and relative viscosity of PVP solutions. This behavior in the rate of degradation was interpreted in terms of viscosity and concentration of polymer solution. With increasing solution concentration, viscosity increases and it causes a reduction in the cavitation efficiency thus, the rate of degradation will be decreased. The experimental results show that the viscosity of polymers decreased with ultrasonic irradiation time and approached a limiting value, below which no further degradation took place. This study confirms the general assumption that the shear forces generated by the rapid motion of the solvent following cavitational collapse are responsible for the breakage of the chemical bonds within the polymer. The effect of polymer concentration can be interpreted in terms of the increase in viscosity with concentration, causing the molecules to become less mobile in solution and the velocity gradients around the collapsing bubbles to, therefore, become smaller.     

Kinetics of the ultrasonic degradation of poly (alkyl methacrylates)

The influence of the alkyl group substituents on the ultrasonic degradation of poly (alkyl methacrylate)s, namely poly (methyl methacrylate) (PMMA), poly (ethyl methacrylate) (PEMA) and poly (butyl methacrylate) (PBMA) was studied. The rate coefficient increased with an increase in the number of carbon atoms in the alkyl group: thus the order of degradation was PBMA>PEMA>PMMA. This was attributed to the scission of the main chain, which increases with the length of the side chain. The ultrasonic degradation of PBMA was investigated in various solvents, at different temperatures and at different ultrasound intensities. The degradation rate coefficients increased logarithmically with the decrease in vapor pressure and increased linearly with an increase in viscosity of the solvent and ultrasound intensity. The effect of three different initiators, benzoyl peroxide (BPO), dicumyl peroxide (DCP) and azo-bisisobutyronitrile (AIBN) on the ultrasonic degradation of PBMA was also studied. The degradation of the polymer decreased in the presence of the initiator. A continuous distribution model was developed for the radical mechanism involved in degradation and was used to determine the degradation rate coefficients of PBMA in presence of initiator. The model indicated that the degradation rate coefficient of the interaction of the PBMA radical with the initiator is independent of the dissociation constant of the initiator.     

Scale invariance of the density fluctuations in films and macromolecular aggregates in poly(styrene) solutions

The specific features of the transformation of a polymer solution into a solid state (film) of an amorphous polymer are investigated using electron microscopy. The correspondence between the characteristics of fractal macromolecular aggregates in a solution and the parameters of the spatial distribution of density fluctuations at the surface of the film is established using a linear atactic poly(styrene) as an example. The correspondence exists under the condition that the packing density of coils does not exceed a critical value at the liquid-solid phase transition point and the polymer concentration in the solution provides the formation of a continuous network of entangled macromolecules.     

Dual-frequency multi-angle ultrasonic processing technology and its real-time monitoring on physicochemical properties of raw soymilk and soybean protein

To improve the soybean protein content (SPC), flavor and quality of soymilk, the effects of dual-frequency ultrasound at different angles (40 + 20 kHz 0°, 40 + 20 kHz 30°, 40 + 20 kHz 45°) on physicochemical properties and soybean protein (SP) structure of raw soymilk were mainly studied and compared with the conventional single-frequency (40 kHz, 20 kHz) ultrasound. Furthermore, the intensity of the ultrasonic field in real-time was monitored via the oscilloscope and spectrum analyzer. The results showed that 40 + 20 kHz 45° treatment significantly increased SPC. The ultrasonic field intensity of 40 + 20 kHz 0° treatment was the largest (8.727 × 10⁴ W/m²) and its distribution was the most uniform. The emulsifying stability of SP reached the peak value (233.80 min), and SP also had the largest particle size and excellent thermal stability. The protein solubility of 40 + 20 kHz 30° treatment attained peak value of 87.09%. 20 kHz treatment significantly affected the flavor of okara. The whiteness and brightness of raw soymilk treated with 40 kHz were the highest and the system was stable. Hence, the action mode of ultrasonic technology can be deeply explored and the feasibility for improving the quality of soymilk can be achieved.     

Rheological,thermal, and mechanical properties of poly(ethylene naphthalate)/poly(ethylene terephthalate) blends

Structural, Theological, thermal, and mechanical properties of blends of poly(ethylene naphthalate) (PEN) and poly(ethylene terephthalate) (PET) obtained by melt blending were investigated using capillary rheometry, differential scanning calorimetry (DSC), scanning electron microscopic (SEM) observation, tensile testing. X-ray diffraction, and ¹H nuclear magnetic resonance (NMR) measurements. The melt Theological behavior of the PEN/PET blends was very similar to that of the two parent polymers. The melt viscosity of the blends was between that of PEN and that of PET. Thermal properties and NMR measurement of the blends revealed that PEN is partially miscible with PET in the as molded blends, indicating that an interchange reaction occurs to some extent on melt processing. The blend of 50/50 PEN/PET was more difficult to crystallize compared with blends of other PEN/PET ratios. The blends, once melted during DSC measurements, almost never showed cold crystallization and subsequent melting and definitely exhibited a single glass transition temperature between those of PEN and PET during a reheating run. Improvement of the miscibility between PEN and PET with melting is mostly due to an increase in transesterification. The tensile modulus of the PEN/PET blend strands had a low value, reflecting amorphous structures of the blends, while tensile strength at the yield point increased linearly with increasing PEN content.     

Influence of the carboxylic acid groups on the structure and properties of sulfonated poly(arylene ether nitrile) copolymer

A series of novel sulfonated poly(arylene ether nitrile) (SPEN) containing carboxylic acid group was successfully synthesized by direct aromatic nucleophilic substitution polycondensation of 2,6-difluorobenzonitrile (DFBN), potassium 2,5-dihydroxybenzenesulfonate (SHQ), phenolphthalin (PPL), and 4,4′-biphenol (BP). The expected chemical structure of copolymers was confirmed by using FTIR and ¹H NMR. To balance the performance for PEM applications, the proportion of four different components were controlled. The influences of the carboxylic acid groups on the structure and properties of SPEN, including thermal and mechanical properties, oxidative stability, water uptake, swelling, proton conductivity, and methanol permeability, were investigated in detail. The results revealed that SPEN membranes containing nitrile and carboxylic acid groups could lead low water absorption, swelling, and methanol penetration. In such a way, efficient proton transport channels were constructed by the formation of the hydrogen bonds. The proton conductivity of SPEN with high sulfonation degree (DS >?0.6) was higher than 0.05 S/cm and increased with increasing temperature. Especially, the conductivity of SPEN-0.6 and SPEN-0.7 reached up to 0.157 and 0.267 S/cm at 80 °C, respectively. Meanwhile, SPEN membranes exhibit low methanol permeability (0.13 ×?10^-6– 0.52 ×?10^-6 cm²·s^?1). Consequently, the highest selectivity of SPEN-0.6 reaches 2.02 ×?10⁵ S·cm^?3·s, which is about 4.5 times higher than that of Nafion 117 (0.45 ×?10⁵ S·cm^?3·s). All the data prove that this series of membranes exhibits excellent comprehensive performance and might have potential applications in direct methanol fuel cells.     

The (τ,d), (d,p) and (d,n) reactions on28Si

The model of a three-particle proton cluster coupled to the quadrupole vibrational field is applied to¹²⁹I. The energy spectrum and spectroscopic factors, as obtained in a (³He,d) stripping reaction, are calculated and compared with experimental data. With the wave functions obtained magnetic-dipole and electric-quadrupole moments are derived.     

Proton-conducting properties of the membranes based on poly(vinyl phosphonic acid) grafted poly(glycidyl methacrylate)

Proton-conducting properties of the graft copolymer electrolytes were examined throughout this work. The homopolymers poly(glycidyl methacrylate), PGMA and poly(vinyl phosphonic acid), PVPA were synthesized by free-radical polymerizations of the monomers glycidyl methacrylate, GMA, and vinyl phosphonic acid, VPA, respectively. The graft copolymers were produced by grafting of PVPA onto PGMA via ring opening of ethylene oxide groups. To examine the influence of the concentration of VPA on the proton conductivity, several graft copolymers were produced at various stoichiometric ratios with respect to monomer repeat units. The materials were characterized by FT-IR and ¹H NMR spectroscopy and the thermal properties were studied by thermogravimetry (TG) and differential scanning calorimetry (DSC). The TGA results demonstrated that the samples are thermally stable up to at least 150 °C. The proton conductivities of humidified and dry samples were studied via impedance spectroscopy. In the anhydrous state, the proton conductivity of P(GMA)-graft-P(VPA)₁₀ was 5 × 10^? 5 S/cm at 150 °C. The proton conductivity of the same material increased with the humidity content and reached to 0.03 S/cm at 80 °C under 50% of RH, which approached to that of Nafion^® at the same humidification level.     

Statistical analysis of the (d,p) and (d,d) reactions on 40Ca

Excitation functions of the ⁴⁰Ca(d, p)⁴¹Ca and ⁴⁰Ca(d, d)⁴⁰Ca reactions have been measured at 45°, 90°, 135° and 170° from E_d = 4.50 to 5.43 MeV in 10 keV steps. Angular distributions of these reactions have been taken at E_d = 4.70, 5.00 and 5.30 MeV from 25° to 170° in 5° steps. Transitions were observed to the excited states for the range 0.0 ≦ E_x ≦ 3.74 MeV in ⁴¹Ca. Rapid fluctuations in the excitation functions and strong variations of the angular distributions with the incident energy were observed, suggesting that the contribution from compound nucleus processes is very large. Various quantities extracted from the experimental data were compared to the predictions of the statistical theories combined with the DWBA theory for the calculation of the direct reaction amplitudes. The results of the present analysis are consistent with the predictions of the standard statistical theories based on the neglect of the channel-channel correlation.     

Electro-optical properties of poly(2-ethynyl-N-hexylpyridinium bromide) and poly(2-ethynyl-N-hexylpyridinium iodide)

Poly(2-ethynyl-N-hexylpyridinium bromide) and poly(2-ethynyl-N-hexylpyridinium iodide) were synthesized by the direct polymerization of 2-ethynylpyridine and the corresponding n-hexyl halides without any additional initiator or catalyst under mild reaction condition. The polymerization proceeded well to give high yield of polymer. The polymer structures were characterized to have the conjugated polymer backbone system having N-hexylpyridyl moieties. The photoluminescence spectra of poly(2-ethynyl-N-hexylpyridinium bromide) and poly(2-ethynyl-N-hexylpyridinium iodide) showed that the photoluminescence peaks are located at 603 and 611 nm corresponding to the photon energy of 2.06 and 2.03 eV, respectively. The electrochemical properties of the resulting polymers were also measured and discussed.     

Anti-corrosive properties of polyaniline,poly(2-toluidine), and poly(aniline-co-2-toluidine) coatings on stainless steel

This study examines the use of polyaniline (PANi), poly(2-toluidine) (PT), and poly(aniline-co-2-toluidine) (co-PT) for corrosion protection of 304-stainless steel (SS) in 0.5 M HCl solution. The PANi, PT, and co-PT coatings were synthesized on SS substrates under cyclic voltammetric (CV) conditions from acetonitrile solution using tetrabuthylammonium perchlorate (TBAP) as supporting electrolyte and perchloric acid (HClO₄) as acid. These coatings were characterized by CV, FTIR, and UV–vis spectroscopy. The ability of PANi, PT, and co-PT to serve as corrosion protective coatings for SS was examined by open circuit potential-time (E_ocp-time), potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) measurements. The results of this study reveal that PANi, PT, and co-PT acts as corrosion protective coatings on SS and every coating gives protection efficiency of greater than 80% after 48 h of immersion in corrosive test solution.     

Influence of lithium potassium zirconate nanoparticles on the electrical properties and structural characteristics of poly(vinyl alcohol) films

We investigated the influence of lithium potassium zirconate (LiKZrO₃) nanoparticles on the electrical properties and structural characteristics of poly(vinyl alcohol) (PVA) films. PVA/LiKZrO₃ nanocomposite films were prepared by casting of aqueous solutions with varying LiKZrO₃ content (0.5, 1.0, and 2.0 wt.%). The dielectric constant (ε′), dielectric loss (ε″), AC conductivity (σ_ac), dielectric loss tangent (tan δ), and electric modulus (M′ and M″) of the nanocomposite films were measured over a range of frequencies at ambient temperature. The results show increases in σ_ac and M′ with frequency, whereas ε′, ε″, and tan δ decreased with increasing frequency. The films were also characterized using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and X-ray diffraction (XRD) techniques. DSC and XRD revealed the nature of LiKZrO₃ nanoparticle interaction with the PVA matrix. TGA analysis revealed an increase in thermal stability of the nanocomposites with increasing nanoparticle concentration. Scanning electron microscopy confirmed uniform dispersion of LiKZrO₃ nanoparticles in the PVA matrix.     

Studies on the Ne(p, d)Ne and Ne(d, p)Ne reactions

Angular distribution measurements have been performed on the ²¹Ne(p, d)²⁰Ne and ²¹Ne(d, p)²²Ne reactions at E_p = 20 MeV and E_d = 10.2 MeV, respectively. In the ²¹Ne(p, d) ²⁰Ne reaction, the prolific formation of the J^π = 2⁺, 1.63 MeV state was characterized by l_n = 2 pickup, and the distribution associated with the 4⁴, 4.25 MeV state was suggestive of a weak l_n = 2 pickup. All of the observed l_n = 1 pickup strength is associated with formation of the 2⁻, 4.97 MeV ²⁰Ne level. The ²¹Ne(d, p)²²Ne results indicate that l_n = 2 transfer is involved in the formation of the 1.28, 3.36, 5.52, 5.63 and 6.65 MeV ²²Ne states. The angular distribution observed for the 2⁺, 4.46 MeV state and also the unresolved 5.33, 5.36 MeV composite of states required both l_n = 0 and l_n = 2 components in the associated distorted-wave Born approximation fits. The spectroscopic factors extracted from the present results are compared with those predicted by the Nilsson model without mixing: Applications of the angular momentum projection rule to the ²¹Ne(d, p)²²Ne reaction are considered.     

Synthesis and spectral-luminescent properties of poly(N-isopropylacrylamide)

The spectral-luminescent characteristics of water and methanol solutions of polymers containing tetraphenylporphyrin substituents were investigated. The water-soluble polymer was obtained by the interaction of poly(N-isopropylamide) containing N-oxysuccinimide substituents with 5-(4-aminophenyl)-10,15,20-triphenylporphyrin. From the synthesized polymer its analog with Zn-porphyrin substituents was obtained. This phenomenon is attributed to the specific features of the conformational behavior of polymeric chains in water solutions. Water solutions of polymers experience a thermally reversible phase transition upon heating, which is accompanied by a considerable enhancement of light scattering. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 4, pp. 483–487, July–August, 2000.