bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of various sterilization methods on the setting and mechanical properties of apatite cement
Authors: Takechi Masaaki , Miyamoto Youji , Momota Yukihiro , Yuasa Tetsuya , Tatehara Seiko , Nagayama Masaru , Ishikawa Kunio
Published: March 2004

Sterilization capability is a necessary requirement for any material that is to be used in a medical application. Therefore, it is necessary for apatite cement (AC) to be sterilized. Because there is little information on the sterilization methods of AC, the aims of this investigation were to evaluate the effects of various sterilization methods, including steam, dry heat, ethylene oxide (EtO) gas, and gamma irradiation sterilizations, on the setting and mechanical properties of AC. In the case of steam sterilization, because AC powder aggregated before setting‐time measurements, the setting time could not be measured. When the powder was sterilized by dry heat or EtO gas, the setting time was prolonged significantly and the wet diametral tensile strength (DTS) value decreased significantly. Therefore, sterilizations with steam, dry heat, or EtO gas were suggested to be inappropriate methods for AC. Accordingly, the following experiments focused on gamma sterilization. The setting time of AC was retarded with an increase in gamma irradiation dose. The wet DTS value decreased with the increase in gamma irradiation dose. There was no compositional change due to the gamma irradiation. The following tests were carried out in order to examine the effect of the gamma irradiation on the setting reaction of AC in detail. Tetracalcium phosphate [TTCP: Ca4(PO4)2O] and dicalcium phosphate anhydrous (DCPA: CaHPO4) were separately irradiated, and the cements were produced with the use of irradiated powder and nonirradiated powder. Although the wet DTS value of AC produced from irradiated TTCP and nonirradiated DCPA decreased with increasing gamma irradiation dose, there was no significant difference. In contrast, the wet DTS value of AC produced from irradiated DCPA and nonirradiated TTCP significantly decreased with the increase in gamma irradiation dose. In conclusion, although the detailed mechanism of the delayed setting time and decreased DTS value was not clarified by the present study, it was found that gamma irradiation affected DCPA more than TTCP. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 69B: 58–63, 2004
Development of medical guide wire of Cu‐Al‐Mn–base superelastic alloy with functionally graded characteristics
Authors: Sutou Yuji , Omori Toshihiro , Furukawa Akihisa , Takahashi Yukinori , Kainuma Ryosuke , Yamauchi Kiyoshi , Yamashita Shuzo , Ishida Kiyohito
Published: March 2004

A new type of medical guide wire with functionally graded hardness from the tip to the end was developed with the use of Cu‐Al‐Mn–based alloys. The superelasticity (SE) of the Cu‐Al‐Mn–based alloys in the tip is drastically improved by controlling the grain size, whereas the end of the wire is hardened using bainitic transformation by aging at around 200–400 °C. Therefore, the tip of the guide wire shows a superelasticity and its end has high stiffness. This guide wire with functionally graded characteristics shows excellent pushability and torquability, superior to that of the Ni‐Ti guide wire. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 69B: 64–69, 2004
Etched implants: A comparative surface analysis of four implant systems
Authors: Szmukler‐Moncler S. , Testori T. , Bernard J. P.
Published: March 2004

Surface texturing by acid etching has recently become popular among dental implant manufacturers. The aim of this study was to compare the surface topography of four implant systems and to check the reproducibility of the industrial process of each implant system. Three implants per system have been selected from three distinct batches. They were observed under a scanning electron microscope (SEM), and roughness was determined with a contact profilometer by measuring five height‐descriptive parameters (Ra, Rq, RzISO, Rt, and Rsk, a texture parameter Sm, and a hybrid parameter RΔq. The analysis showed that each implant system displayed a distinct surface topography that could not be mistaken. When sandblasting was performed prior to etching, surface topography was a combination of macro‐ and microroughness. The roughness and the amount of remaining sand varied among the batches, showing that the industrial process is not fully developed. Deviation from the released technical information was found for two out of four implant manufacturers. Based on the available biological and clinical data on textured surfaces, it is suggested that it is bone interlocking at the interface that maintains the biological properties of textured surfaces, rather than a strong implant fixation per se. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 69B: 46–57, 2004
The effect of six years of water storage on resin composite bonding to human dentin
Authors: Frankenberger Roland , Strobel Wolfgang O. , Lohbauer Ulrich , Krämer Norbert , Petschelt Anselm
Published: March 2004

The aim of this in vitro study was to evaluate dentin bond strength and marginal adaptation of direct resin composite fillings after different storage times. Three hundred sixty cavities were prepared in discs of freshly extracted human third molars and filled with resin composites. Multistep self‐etching adhesives (Syntac Classic, A.R.T. Bond, both with and without total etching), three‐step etch‐and‐rinse adhesives (Scotchbond Multi‐Purpose Plus, EBS), and two‐step etch‐and‐rinse adhesives (Prime&Bond 2.0, Syntac Single‐Component) were used for bonding. After 1, 90, and 2190 days of water storage and 24 h thermocycling (1150 cycles), push‐out testing was performed. From the 6‐year group, replicas were made after 1 day, 90 days, and 1, 2, 3, 4, 5, and 6 years, and examined regarding marginal adaptation under an SEM (× 200 magnification). In all groups under investigation, push‐out bond strengths remained stable after 90 days; however, the strengths significantly decreased after 6 years of water storage. The two‐step systems exhibited lower bond strengths than three‐step systems after 6 years. Marginal analysis revealed a significant loss regarding the percentage of perfect margins having been stable after 2 years for the three‐step etch‐and‐rinse systems. Overall, the older three‐step systems proved to be more effective than the simplified adhesives Syntac Single‐Component and Prime&Bond 2.0 with regard to bond strength and marginal adaptation. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 69B: 25–32, 2004
Apatite formation on the surface of wollastonite/tricalcium phosphate composite immersed in simulated body fluid
Authors: Huang Xiang , Jiang Dongliang , Tan Shouhong
Published: March 2004

Wollastonite/tricalcium phosphate composites were prepared and immersed in SBF for various periods to investigate the apatite‐formation mechanism on their surfaces. Surface morphologies and composition before and after immersion were analyzed by SEM and EDS technologies. The concentration changes of calcium, silicon, and phosphorus in SBF due to the immersion of the samples were measured with inductively coupled plasma atomic emission spectroscopy, and the corresponding pH values in SBF were recorded. XRD and IR were used to examine the changes in crystalline phases and functional groups. It was found that, after immersion for 1 day, the samples were covered by pom‐pom–like apatite granules, resulting from the dissolution of wollastonite and the simultaneous transformation of TCP. This quickly led to the subsequent precipitation of another apatite layer, which covered the earlier‐formed surface completely. These results indicate that the wollastonite/tricalcium phosphate composite is a potential biomaterial candidate because of its high bioactivity and in situ porous structure. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 69B: 70–72, 2004
Protein‐loaded bioresorbable fibers and expandable stents: Mechanical properties and protein release
Authors: Zilberman Meital , Schwade Nathan D. , Eberhart Robert C.
Published: March 2004

There is an increasing interest in bioresorbable polymeric stents for coronary, urethral and tracheal applications. These stents can support body conduits during their healing process and release biologically active agents from an internal reservoir to the surrounding tissue. A removal operation is not needed. Bioresorbable poly(L‐lactic acid) fibers were prepared through melt spinning accompanied by a postpreparation drawing process. Novel expandable bioresorbable stents were developed from these fibers. Bioresorbable microspheres containing albumin were prepared and attached to the stents, to serve as a protein reservoir coating. The controlled release of albumin from the microsphere‐loaded stent was studied. The fibers combine high strength and modulus, together with good ductility and flexibility. An increase in draw ratio increases the tensile strength and modulus and decreases the ultimate strain. The stents demonstrated excellent initial radial compression strength and good in vitro degradation resistivity, which makes them applicable for supporting blood vessels for at least 20 weeks. Microspheres bound to these stents enable effective protein loading, without reducing the stent's mechanical properties. The protein release from the microsphere‐loaded stent occurs by diffusion, is determined mainly by the initial molecular weight of the bioresorbable polymer and its erosion rate, and is strongly affected by the microsphere structure. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 69B: 1–10, 2004
Sol‐gel preparation and in vitro test of fluorapatite/hydroxyapatite films
Authors: Cheng Kui , Weng Wenjian , Qu Haibo , Du Piyi , Shen Ge , Han Gaorong , Yang Juan , Ferreira J. M. F.
Published: March 2004

Fluorapatite/hydroxyapatite (FA/HA) films have been demonstrated to be a good alternative to pure hydroxyapatite (HA) ones in medical applications because of their bioactivity and relatively low solubility. In this study, Ca(NO3)2, P2O5, and HPF6 were used to prepare FA/HA films on Ti6Al4V substrate with the use of a sol‐gel method. The F contents in the films could be tailored by adjusting the amount of HPF6 added. The in vitro evaluation of the films was carried out in both SBF9# solution and TRIS buffer solution. The films with appropriate F contents showed a better ability to induce calcium phosphate deposition on their surfaces than either pure HA film and FA/HA films with even higher F content, as well as smaller dissolution amounts than HA film in TRIS buffer solution. Hence, the FA/HA films obtained in this work integrate both good bioactivity and stability, and could be a better choice for bioactive film on titanium alloys to produce high‐quality implants. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 69B: 33–37, 2004
Analysis of cellular morphology, adhesion, and proliferation on uncoated and differently coated PVC tubes used in extracorporeal circulation (ECC)
Authors: Moreira Patrícia da Luz , Marreco Paula Rulf , Moraes Angela Maria , Wada Maria Lúcia Furlan , Genari Selma Candelária
Published: March 2004

The biggest challenge to improve extracorporeal circulation (ECC) circuits lays on avoiding platelet adhesion to their surfaces, because this contributes to thrombus formation, resulting in the activation of blood coagulation. One approach to minimize this effect is to improve the biocompatibility of ECC circuits by modifying their surfaces. This can be achieved by coating them with heparin or phospholipids. The present study investigated the adhesion and morphology characteristics of fibroblastic and blood cells cultured on uncoated poly (vinyl) chloride PVC tubes as well as on heparin, phosphatidylcholine (DMPC), and phosphatidylethanolamine (DMPE) ‐coated tubing. The results showed the importance of uniform coating regardless of the substance used, because the coatings cover the grooves on PVC surfaces, which favor cell adhesion. The comparison among the three different coatings showed the best biocompatibility results for the PVC tubes coated with heparin, followed by the coating with DMPE and with DMPC. For all coated tubes, cells did not spread on the PVC surfaces and, consequently, did not adhere to their surfaces, increasing the overall biocompatibility of PVC tubes. However, possible DMPE′s alkylation, caused by sterilization, resulted in increased material hydrophobicity, which explains the decrease in fibroblastic adhesion. Furthermore, sterilization of DMPC‐PVC improves its hydrophilic character, also decreasing adhesion. Based on these results, coating PVC with the phospholipids DMPC and DMPE seems to be a promising technique to improve the biocompatibility of PVC tubes, and is worthy of further investigation. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 69B: 38–45, 2004
Sublethal concentrations of Au (III), Pd (II), and Ni(II) differentially alter inflammatory cytokine secretion from activated monocytes
Authors: Wataha John C. , Lewis Jill B. , Volkmann Keith R. , Lockwood Petra E. , Messer Regina L. W. , Bouillaguet Serge
Published: March 2004

Many transition metals have been viewed collectively as nonspecific biological toxins in cells, which has limited investigation into their possible therapeutic effects. In the current study, the effects of Au(III), Ni(II), and Pd(II) on the differential secretion of cytokines from monocytes has been investigated. This is critical to understanding any therapeutic potential of these metals, their allergenicity, or the clinical effects of current metal therapies such as chrysotherapy. Lethal concentrations (defined as > 50% suppression of mitochondrial succinate dehydrogenase (SDH) activity) of metals were determined by dose‐response curves with the use of 72 h exposures to human THP‐1 monocytes. Then, secretion of TNFα, IL1β, and IL6 were measured after the monocytes were exposed to sublethal concentrations of metals, with or without stimulation by lipopolysaccharide. The concentrations of Au(III), Pd(II), and Ni(II) required to suppress SDH activity by 50% were found to be 255, 270, and 90 μM, respectively. No sublethal concentration of any metal alone caused secretion of the cytokines. However, LPS‐induced cytokine secretion was significantly and differentially altered by sublethal concentrations of each metal. Differential responses were highly dependent on metal concentration and involved both suppression and potentiation of the LPS activation. In the case of Ni(II), potentiation of TNFα, IL1β, and IL6 ranged from 200% for TNFα to over 1200% for IL6. Metals such as Au(III), Pd(II), and Ni(II) differentially alter cytokine expression from monocytes. These results imply that metals have more specific effects on cell signaling than previously assumed. These results also are important in explaining multiple clinical effects often seen with chrysotherapy, identifying potential new avenues for metal therapy, and understanding the inflammatory effects of metals such as nickel. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 69B: 11–17, 2004
Development of a recombinant human collagen‐type III based hemostat
Authors: Yang C. , Hillas P. , Tang J. , Balan J. , Notbohm H. , Polarek J.
Published: March 2004

Animal‐tissue‐derived collagen, containing mostly type I collagen with a minor amount of type III collagen, has been widely used in the production of hemostats for many decades, although it has been known for a long time that type III collagen is more likely to induce platelet aggregation in vitro. Because it is hard to purify type III from animal tissue, it has not been possible to correlate this finding with in vivo data. In this report, it is demonstrated that recombinant human collagen III fibrils are more capable of inducing platelet aggregation in vitro than those comprised of bovine collagen I, in agreement with previously published data on tissue‐derived type III collagen. When formed into three‐dimensional matrices, the use of type III collagen results in formulations with better mechanical integrity, larger surface area, and higher hemostatic activity in a rabbit spleen injury model as compared with commercially available hemostats formed from bovine type I collagen. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 69B: 18–24, 2004
Wear‐particle–induced osteoclast osteolysis: The role of particulates and mechanical strain
Authors: MacQuarrie Robyn A. , Fang Chen Ying , Coles Chad , Anderson Gail I.
Published: March 2004

Periprosthetic osteolysis involves osteoclast activation by wear particulates and their exposure to mechanical perturbation through exposure to shear forces generated by periprosthetic fluid as well as interface micromotion. This study aimed to determine the interactions between wear particulates, mechanical stimulation, and osteoclasts. In static cultures, wear particulates increased osteoclast differentiation. Addition of neutralizing antibodies to RANKL (receptor activator of nuclear factor kappa ligand) inhibited the particle‐induced increase in osteoclast numbers. Cyclic 5000 microstrains were applied with the use of a custom‐built device to marrow‐derived cultures to assess the effect on osteoclast differentiation. Mechanical strain application alone decreased osteoclast differentiation, which was further decreased by the addition of particles despite increases in the soluble RANKL to osteoprotegerin (OPG) ratio. Mechanical strain alone induced mature osteoclast apoptosis in a dose‐dependent manner. In contrast, in the mature osteoclast model, the addition of nonmetal particulates protected the osteoclasts from becoming apoptopic. Titanium (Ti) and cobalt chromium (CoCr) particles, however, induced osteoclast apoptosis, whereas polyethylene (PE) and polymethylmethacrylate (PMMA) did not. Wear particulates and mechanical stimulation interact via an eicosanoid‐dependent pathway to alter osteoclast function and survival. The addition of mechanical perturbation to a particle‐laden system thus appears to enhance the potential for osteolytic activity by enhancing osteoclast survival. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 69B: 104–112, 2004
The physicochemical properties of the solidification of calcium phosphate cement
Authors: Liu Changsheng , Huang Yue , Chen Jianguo
Published: March 2004

In this article, the physicochemical properties of the solidification of calcium phosphate cement (CPC) were investigated, and the components of the solidified body and the characteristics involved in the application were measured. The setting process of CPC was moderate and slightly exothermic, the heat liberation rate was slow, and the temperature increased little. At the initial stage of the hydration, the compressive strength rose linearly with time, and reached the maximum value after 4 hours. The volume was slightly shrunken by 1% during the setting process, and the total heavy metal content was below 2 ppm. The porosity of the solidified body was about 30%, which was mainly the gel pore with size below 0.1 μm. The final product of hydration was low crystalline hydroxyapatite (HAP). Its real density was 2.859 g/cm3, which was lower than the theoretical value. This may be due to the existence of lattice defects, which will lead to a slight rise in solubility when leached in physiological saline. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 69B: 73–78, 2004
Effects of neutral sodium hydrogen phosphate on the setting property and hemostatic ability of hydroxyapatite putty as a local hemostatic agent for bone
Authors: Momota Yukihiro , Miyamoto Youji , Ishikawa Kunio , Takechi Masaaki , Yuasa Tetsuya , Tatehara Seiko , Nagayama Masaru
Published: March 2004

Hydroxyapatite (HAP) putty has been reported to have good hemostatic ability and excellent biocompatibility. Although the setting reaction of HAP putty and resulting transformation to HAP is the reason for this excellent biocompatibility, it also limits the handling period. In this study, the relationship between the setting reaction of HAP putty and its hemostatic ability was investigated, where neutral sodium hydrogen phosphate concentration and postpreparation time were used as indexes. A higher concentration of neutral sodium hydrogen phosphate was found to result in decreased hemostatic ability. The hemostatic ability of HAP putty decreased with time after its preparation; thus it was important to use HAP putty within 10 min after its preparation. The adhesive strength of HAP putty to bone increased with time. Therefore reliable hemostasis can be expected with HAP putty. Although the limited handling time is a drawback, HAP putty is thought to have a good potential as a hemostatic agent—it is highly reliable, and has a high hemostatic ability with excellent biocompatibility. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 69B: 99–103, 2004
Hydrolytic degradation and cracks in resin‐modified glass‐ionomer cements
Authors: Fano Luca , Fano Vincenzo , Ma Wanyun , Wang Xiaoguang , Zhu Feng
Published: March 2004

Water‐absorption affects the basic properties of resin‐modified glass‐ionomer cements (RMGICs). Fick's law is usually invoked to explain the absorption process. The purpose of this study is to show that the absorption in accordance with the Fickian model cannot be extended to the whole of the specimen, and that microcrack formation is the main degradation mechanism for specimens cured in a closed environment. For this purpose, flat disk‐shaped paste specimens 1.5 mm thick (aspect ratio 4), irradiated in closed conditions between two glass slides and stored in water for ≈20 months, were analyzed periodically gravimetrically and under confocal fluorescence microscopy, with absorbed eosin used as the fluorescent probe. At pH 7.0, the specimen surface (10–20 micrometers in depth) absorbed water rapidly, swelled, and disintegrated in 20–40 days. Long‐term storage produced isolated cracks and grains, no progress in the swelling, and a slow weight decrease. A lower pH (pH 3.5) produced a significant increase of the number of microcracks. The decrease in the irradiation time (30 s or less) enhanced the erosion process, producing very broad cracks. It was concluded that the prevalent mechanism of long‐term hydrolytic degradation was based on the slow formation of cracks, whereas only in the early stage of storage did absorption occur quickly in accordance with the Fickian diffusion. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 69B: 87–93, 2004
Surface treatment of injectable strontium‐containing bioactive bone cement for vertebroplasty
Authors: Zhao F. , Lu W. W. , Luk K. D. K. , Cheung K. M. C. , Wong C. T. , Leong J. C. Y. , Yao K. D.
Published: March 2004

A novel injectable bioactive bone‐bonding cement (SrHAC) composed of strontium‐containing hydroxyapatite (Sr‐HA) as the inorganic filler and bisphenol A diglycidylether dimethacrylate (Bis‐GMA) as the organic matrix for vertebroplasty was developed previously. In this study, the Sr‐HA powders were surface treated with methyl methacrylate (MMA) to improve the interface integration of the two phases. After surface treatment, the compression strength and Young's modulus, which were tested after immersion in distilled water at 37 °C for 24 h according to ISO 5833, were increased by 68.65 % (p < .001) and 31.02% (p < .001), respectively. The bending strength and bending stiffness of the bioactive bone cement were significantly improved by 54.44% (p < .001) and 83.90% (p < .001). In addition, the handling property of the cement was also enhanced. In vitro biomechanical testing showed that the stiffness of the fractured spine recovered to 82.5% (p < .01) of the intact condition after cementation with surface‐treated SrHAC. The failure load of the spine cemented with original and MMA‐treated SrHAC improved by 14.25% (p < .05) and 46.91% (p < .05) in comparison with the fractured spines. Results from this study revealed that the MMA‐treated SrHAC has a better mechanical effect for orthopedic applications. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 69B: 79–86, 2004
Transmittance of a bioceramic dental restorative material based on calcium aluminate
Authors: Engqvist Håkan , Lööf Jesper , Uppström Stina , Phaneuf Mike W. , Jonsson Jacob C. , Hermansson Leif , Ahnfelt Nils‐Otto
Published: March 2004

This article investigates the transmittance of a new ceramic filling material as a function of time, thickness, wavelength, and addition of pigments. In the hardened state the ceramic material is composed of hydrates, calcium aluminate, and glass fillers. The radiopacity of the investigated material is also measured. The results of the transmittance are compared to a commercial glass ionomer cement (Fuji II) and resin composite (Tetric Ceram). The transmittance increased with time from low values after 1 h to values close to the glass ionomer cements after 1 week. The resin composite had almost twice the transmittance as the calcium aluminate material and the glass ionomer cement. The amount of light passing through the material was dependent on both the sample thickness and the wavelength. Samples of 0.5‐mm thickness transmitted almost twice as much as 1‐mm‐thick samples. Regarding the wavelength, blue light was scattered very effectively (low transmittance), whereas red light was not (high transmittance). Addition of pigments lowered the transmittance. The radiopacity was slightly higher than that of enamel. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 69B: 94–98, 2004
Car‐Parrinello simulations with a real space method
Authors: Schmid Rochus
Published: March 2004

An approach for Car‐Parrinello type molecular dynamics simulations using real space discretized wave functions is presented. The implementation uses a higher order finite difference approximation for the Laplacian in the kinetic energy operator and in the Poisson equation for the evaluation of the Hartree energy. Norm conserving pseudopotentials are employed to replace the nucleus‐core interactions. Both nuclei and wave functions are propagated with a second‐order Verlet propagator with a timestep comparable to standard plane wave implementations. The orthonormality constraints are fulfilled via Lagrange multipliers. Both periodic and nonperiodic boundary conditions can directly be imposed within the real space approach. In order to maintain energy conservation both forces on the nuclei and the wave functions must be sufficiently accurate. It is shown that the spurious energy dependence on the nuclear positions with respect to the grid points, which is an inevitable artifact of the discretization, is mirrored in the nuclear forces, and does not affect energy conservation. In contrast to the plane wave methodology, the Hartree energy is calculated via an iterative solution of the Poisson equation. As a result, the quality of the forces on the wave function crucially depends on its convergence, as well as on the accuracy of the approximation for the boundary values in nonperiodic calculations. The influence of these factors on the energy conservation is investigated. It is shown that Car‐Parrinello simulations can be performed with real space wave functions, given a proper prescription to calculate the Hartree potential is used. © 2004 Wiley Periodicals, Inc. J Comput Chem 25: 799–812, 2004
Continuous medium theory for nonequilibrium solvation: II. Interaction energy between solute charge and reaction field and single‐sphere model for spectral shift
Authors: Li Xiang‐Yuan , Fu Ke‐Xiang , Zhu Quan , Shan Min‐Hua
Published: March 2004

On the basis of continuous medium theory, a model for evaluation of spectral shifts in solution has been developed in this work. The interaction energy between solute dipole and reaction field and the self‐energy of the reaction field have been formulated through derivations. Applying the interaction energy expression together with the point dipole approximation to the case of spherical cavity produces new formulations of spectral shifts. The same expression of electrostatic free energy of the nonequilibrium state is achieved by integrating the change of the electrostatic free energy for a charging process. Moreover, generalized formulations evaluating spectral shifts have been established in the charge‐potential notation, and the reduction of them to the point dipole case consistently leads to the same formulations of spectral shifts as those by interaction energy approach. Mutual supports provide convincing evidences for the reliability of the present results. In this work, attentions are particularly paid to the conclusion of zero self‐energy of the reaction field, which is different from the previous theory. Reasoning and arguments are given on this point. From the present derivations, it is concluded that the spectral shifts of light absorption and emission were theoretically exaggerated in the past, in particular, by a factor of 2 for the spectral shift sum. © 2004 Wiley Periodicals, Inc. J Comput Chem 25: 835–842, 2004
Modification of the Wiener index 4
Authors: Yang Feng , Wang Zhen‐Dong , Huang Yun‐Ping
Published: March 2004

A novel topological index WF is defined by the matrices X, W, and L as WF = XWL. Where L is a column vector expressing the characteristic of vertices in the molecule; X is a row vector expressing the bonding characteristics between adjacent atoms; W is a reciprocal distance matrix. The topological index WF, based on the distance‐related matrix of a molecular graph, is used to code the structural environment of each atom type in a molecular graph. The good QSPR/QSAR models have been obtained for the properties such as standard formation enthalpy of inorganic compounds and methyl halides, retention indices of gas chromatography of multiple bond‐containing hydrocarbons, aqueous solubility, and octanol/water partition of benzene halides. These models indicate that the idea of using multiple matrices to define the modified Wiener index is valid and successful. © 2004 Wiley Periodicals, Inc. J Comput Chem 25: 881–887, 2004
The calculation of the vibrational frequencies of crystalline compounds and its implementation in the CRYSTAL code
Authors: Pascale F. , Zicovich‐Wilson C. M. , López Gejo F. , Civalleri B. , Orlando R. , Dovesi R.
Published: March 2004

The problem of numerical accuracy in the calculation of vibrational frequencies of crystalline compounds from the hessian matrix is discussed with reference to α‐quartz (SiO2) as a case study and to the specific implementation in the CRYSTAL code. The Hessian matrix is obtained by numerical differentiation of the analytical gradient of the energy with respect to the atomic positions. The process of calculating vibrational frequencies involves two steps: the determination of the equilibrium geometry, and the calculation of the frequencies themselves. The parameters controlling the truncation of the Coulomb and exchange series in Hartree–Fock, the quality of the grid used for the numerical integration of the Exchange‐correlation potential in Density Functional Theory, the SCF convergence criteria, the parameters controlling the convergence of the optimization process as well as those controlling the accuracy of the numerical calculation of the Hessian matrix can influence the obtained vibrational frequencies to some extent. The effect of all these parameters is discussed and documented. It is concluded that with relatively economical computational conditions the uncertainty related to these parameters is smaller than 2–4 cm−1. In the case of the Local Density Approximation scheme, comparison is possible with recent calculations performed with a Density Functional Perturbation Theory method and a plane‐wave basis set. © 2004 Wiley Periodicals, Inc. J Comput Chem 25: 888–897, 2004
Carbon‐14 wiggle‐match dating of peat deposits: advantages and limitations
Authors: Blaauw Maarten , Van Geel Bas , Mauquoy Dmitri , Van Der Plicht Johannes
Published: March 2004

Carbon‐14 wiggle‐match dating (WMD) of peat deposits uses the non‐linear relationship between 14C age and calendar age to match the shape of a series of closely spaced peat 14C dates with the 14C calibration curve. The method of WMD is discussed, and its advantages and limitations are compared with calibration of individual dates. A numerical approach to WMD is introduced that makes it possible to assess the precision of WMD chronologies. During several intervals of the Holocene, the 14C calibration curve shows less pronounced fluctuations. We assess whether wiggle‐matching is also a feasible strategy for these parts of the 14C calibration curve. High‐precision chronologies, such as obtainable with WMD, are needed for studies of rapid climate changes and their possible causes during the Holocene. Copyright © 2004 John Wiley & Sons, Ltd.
Tephrostratigraphical evidence for the timing of pleistocene explosive volcanism at Jan Mayen
Authors: Hunt John B.
Published: March 2004

Wavelength dispersive (WDS) electron microprobe analysis of glass shards recovered from Pleistocene sediments at Ocean Drilling Program Hole 907A (Leg 151) has been used to define key Pleistocene tephrochronostratigraphical markers for the Greenland–Iceland–Norwegian (GIN) seas. Two tephras have particularly distinctive geochemistry, making them useful as marker horizons in cores from the Iceland Plateau, and potentially further afield. These tephras enable the construction of a sedimentation rate history that indicates reduced sediment deposition in the mid‐Brunhes magnetochron, possibly through reduced carbonate preservation. No significant geochemical weathering of the Iceland Plateau tephra sequence has occurred. The geochemical signature of a key tephra, dated to 577–640 ka, can be attributed to the Jan Mayen rock suite, demonstrating unambiguously the explosive potential of Jan Mayen and its potential to contribute to the North Atlantic tephra record. Copyright © 2004 John Wiley & Sons, Ltd.
Characterisation of frozen orange juice by ultrasound and wavelet analysis
Authors: Lee Suyong , Pyrak‐Nolte Laura J , Cornillon Paul , Campanella Osvaldo
Published: March 2004

Ultrasound technology was used to analyse the freezing behaviour of orange juice. The ultrasonic properties of orange juice, specifically velocity and attenuation coefficient, were characterised as the temperature was decreased from 20 to −50 °C. The results were compared with NMR free induction decay data and correlated with the amount of unfrozen water present in the frozen sample. The velocities of longitudinal waves (P‐wave) and shear waves (S‐wave) in frozen orange juice were measured, yielding values of around 4000 and 2000 m s−1 respectively. They were related to the amount of unfrozen water in the frozen sample. The elastic moduli of the samples at different temperatures were obtained from the measured ultrasonic velocities. Significant changes in the attenuation of the ultrasonic waves propagated through the frozen sample were observed as a result of ice nucleation and growth. Information about the spectral behaviour of the ultrasound signal was obtained by means of wavelet analysis. The analysis provided a direct measure of the spectral content of the ultrasonic waves over time and showed the variation in the ultrasonic velocity dispersion with temperature. Significant velocity dispersions occurred for frequencies less than 1 MHz. Copyright © 2004 Society of Chemical Industry
Variation in the composition of Cretan avocado cultivars during ripening
Authors: Vekiari Stavroula A , Papadopoulou Parthena P , Lionakis Spiros , Krystallis Athanasios
Published: March 2004

The effect of ripening on the chemical characteristics of fruits of the avocado (Persea americana) cultivars Ettinger, Fuerte and Hass was investigated. A study of some quality parameters of these main avocado cultivars grown on the island of Crete was performed. As the fruit ripened, a decrease in the moisture content was observed, with a high degree of correlation for all the cultivars. At the same time an increase in the fat and protein contents was measured. The content of total sugars was high in the unripe fruit but decreased during ripening. The fatty acid composition of the oil extracted from the fruit pulp was determined by gas chromatographic analysis. The oil of the edible portion of the fruit was rich in oleic, palmitic, linoleic and palmitoleic acids, while stearic acid was present in small quantities. During the ripening process the amount of palmitic acid decreased and that of oleic acid increased in all the cultivars. The ratio of polyunsaturated to saturated fatty acids, which is considered as an indicator of the nutritional value of the fruit, was also calculated. No significant differences were observed between the cultivars. Principal component analysis was also performed to examine the relationship among the quality variables of the cultivars. From these data, Fuerte was considered to be the cultivar with the best characteristics. Copyright © 2004 Society of Chemical Industry
Contents of hypericin and pseudohypericin in five commercial products of St John's wort (Hypericum perforatum)
Authors: Wang Zhao‐Jun , Lin Shih‐Mei , Hu Miao‐Lin
Published: March 2004

Hypericin and pseudohypericin are the two major dianthrones of St John's wort (SJW, Hypericum perforatum) that are reported to have antidepressant and antiviral effects. In this study we used methanol extracts of five commercial SJW products to determine the two congeners using a modified reverse phase HPLC method with gradient elution. One SJW product is specified by the manufacturer to contain 340 µg hypericin per tablet (170 mg extract), while the other four products are specified to contain 900 µg hypericin per tablet (300 mg); none of the products is claimed to contain pseudohypericin. Our results showed that the actual contents of hypericin in these products ranged from 1.7 to 38.5% of the claimed amounts. However, the amounts of pseudohypericin were in general much higher than those of hypericin. When hypericin and pseudohypericin were combined as total hypericin, the four products that supposedly contain 900 µg per tablet were found to contain 26, 484, 587 and 615 µg total hypericin per tablet, or 2.9, 53.8, 65.2 and 68.3% of the claimed hypericin contents respectively. The product which supposedly contains 340 µg hypericin per tablet was found to contain 388 µg total hypericin per tablet, or 114% of the claimed hypericin content. The relatively low hypericin contents measured in these products are not a result of losses during extraction, because the two congeners had high recoveries (93.7 and 94.3% for hypericin and pseudohypericin respectively) when added before methanolic extraction to an SJW product with known amounts of the two congeners. Thus our results show that the commercial SJW products vary greatly in their amounts of total hypericin and that pseudohypericin, rather than hypericin, is the major hypericin in these products. Copyright © 2004 Society of Chemical Industry
Protein and amino acids contents of Libyan dates at three stages of development
Authors: Ishurd Omar , Zahid Muhammad , Xiao Peng , Pan Yuanjiang
Published: March 2004

The protein and amino acid contents of three Libyan date varieties (Taasfirt, Bikrari and Khadhrai) at different stages of fruit development were determined. The protein concentration in all three varieties was highest at the green stage. Seventeen amino acids were detected and quantified; their concentrations (dry weight basis) were higher in Khadhrai and Bikrari than in Taasfirt. At the green stage the concentrations of glutamic acid, aspartic acid, lysine, leucine, alanine and serine were highest. At the yellow and ripe stages, glutamic acid, aspartic acid, lysine, leucine, proline and glycine were present in high concentrations. For most amino acids the concentrations were higher at the yellow stage than at the ripe stage. Copyright © 2004 Society of Chemical Industry
Nutritional evaluation of peas for ducks
Authors: Nyachoti Charles M , Onyango Edward M , Omogbenigun Olufemi F , Adeola Olayiwola
Published: March 2004

The nutritive value of four pea cultivars (AC Advantage, Carneval, CDC Mozart and Keoma) and soybean meal (SBM) was evaluated in a 102 h study with 48 male White Pekin ducks. All birds were tube‐fed 25 g of dextrose at 24 and 30 h after feed withdrawal, then 25 g of each feedstuff was tube‐fed to eight ducks at 48 and 54 h after feed withdrawal. Excreta were quantitatively collected during the next 54 h. Endogenous nitrogen, amino acids and energy per bird in the 54 h collection period were 1.06 ± 0.58 g, 0.047 ± 0.025 g and 0.098 ± 0.049 MJ respectively. There were differences (P < 0.05) in apparent amino acid digestibilities (AAAD) and true amino acid digestibilities (TAAD). On average, AAAD were 82.8, 82.0, 70.3, 82.4 and 77.7% and TAAD were 89.4, 89.2, 82.3, 89.5 and 85.3% for SBM, AC Advantage, Carneval, CDC Mozart and Keoma respectively. The nitrogen‐corrected apparent and true metabolisable energy values did not differ among the pea diets and were 13.36 ± 0.071 and 14.59 ± 0.071 MJ kg−1 respectively. Respective values for SBM were 12.16 ± 0.16 and 13.39 ± 0.16 MJ kg−1 and both were lower (P < 0.05) than in peas. Copyright © 2004 Society of Chemical Industry
Chemical composition of shell and flesh of three prawn samples from Lagos lagoon
Authors: Adeyeye E Ilesanmi , Adubiaro H Omolara
Published: March 2004

The protein, ash, fibre and individual mineral ion contents of three species of prawn taken from the Lagos lagoon were determined. The median liveweights of Macrobrachium vollenhovenii (Herklots), Palaemon species A (Powell) and Penaeus notialis were respectively, 25.52 g (shell + head 16.76 g; flesh 9.26 g), 3.15 g (shell + head 1.71 g; flesh 1.44 g) and 5.11 g (shell + head 2.14 g; flesh 2.96 g). All (shell + head) samples had high protein, ash and fibre contents but only the protein content was high in the flesh, which had low or undetectable quantities of fibre. The fat and carbohydrates contents were generally low. In M vollenhovenii the (shell + head) was a better source of Mg, Zn, Cu and K than the flesh, which was a better source of Ca, Ni, P, Fe, Co and Na. In P species A the (shell + head) was a better source of Ca, Mg, P, Cu, Co, Na and K than the flesh (higher in Zn and Ni). In P notialis the (shell + head) was the better source of Ca, Zn, P, Fe and Co and the flesh the better source of Mg, Ni, Fe, Na and K. Copyright © 2004 Society of Chemical Industry
Effect of melon seed meal addition on some quality characteristics of chicken sausages
Authors: Abiola Samuel S , Kadiri Elizabeth I , Kareem Talubi T
Published: March 2004

A study was conducted in which melon seed meal (MSM) replaced fat at levels of 0, 330, 660 and 1000 g kg−1 in four batches of chicken sausage. The chemical, storage and sensory properties of the sausages were determined in a meat processing laboratory. MSM increased both the ash and protein contents but decreased the ether extract content. The highest ether extract content (257.5 g kg−1) was obtained for batch 1 (control) while the lowest value (241.5 g kg−1) was recorded for batch 4. Differences of refrigeration weight loss were statistically significant (P < 0.05) while the results recorded for cooking weight loss did not show any particular trend. MSM decreased refrigeration weight loss and improved overall acceptability of the finished products. Copyright © 2004 Society of Chemical Industry
Molecular studies of pressure/temperature‐induced structural changes in bovine β‐lactoglobulin
Authors: Aouzelleg Amar , Bull Laura‐Anne , Price Nicholas C , Kelly Sharon M
Published: March 2004

β‐Lactoglobulin in 50 mM Tris/HCl buffer at pH 7 was subjected to combined pressure and temperature treatments using a central composite experimental design. Pressures up to 294 MPa, temperatures up to 62 °C and processing times up to 30 min were studied. The molecular structure at the secondary and tertiary levels was analysed post‐processing using far‐ and near‐UV circular dichroism. It was found that, although the pressures applied were moderate, the far‐UV circular dichroism spectra showed important changes corresponding to an increase in α‐helix content. The tertiary structure was almost completely lost for the highest processing intensities. This suggests a transition to the molten globule state. The percentage change in molar ellipticity at 293 nm (tertiary structure) was found to be linearly connected to the three independent variables, hence possibly allowing process optimisation for that response. Pressure was found to be the most important parameter to bring about the molecular changes at the two molecular levels investigated. Copyright © 2004 Society of Chemical Industry
Flavour characteristics of Ilex paraguariensis infusion, a typical Argentine product, assessed by sensory evaluation and electronic nose
Authors: Grigioni Gabriela , Carduza Fernando , Irurueta Martín , Pensel Norma
Published: March 2004

Sensory evaluation and electronic nose (E‐nose) technology were applied to study two formulations of a new product intended to have organoleptic characteristics similar to those of Ilex paraguariensis (Saint Hilaire) infusions. Infusions prepared from I paraguariensis, called ‘yerba mate’ in South America, possess distinct sensory properties that were described by trained panellists using a lexicon of 17 terms. The two commercial products were formulated by combining various flavour components and processed as instant powders for infusion. Results from the sensory panel showed that it would be necessary to change the product formulation in order to achieve desirable yerba mate characteristics. Odour, mouthfeel and sweetness intensities would have to be improved. The E‐nose had an array of 32 sensors which were able to discriminate between infusions prepared from yerba mate and from the instant powders. Using stepwise discriminant analysis, the group of sensors that contributed to this classification was identified. The response of these sensors correlated (P < 0.05) with yerba mate odour, mouthfeel and sweetness attributes. Comparison of the results obtained by the two methodologies enabled the E‐nose procedure to be improved and showed that this methodology is suitable for food product development and is a good complement to sensory evaluation. Copyright © 2004 Society of Chemical Industry
Influence of cultivar, storage and cooking on the mechanical properties of winter squash (Cucurbita maxima)
Authors: Ratnayake RM Sunil , Hurst Paul L , Melton Laurence D
Published: March 2004

Texture profile analysis and rupture tests were carried out on raw and cooked tissues of ‘Delica’, ‘CF 2’ and ‘CF 4’ buttercup squash cultivars and ‘Red Warren’ pumpkin during storage. The raw tissues of ‘CF 2’ were the firmest, exhibiting high tissue strength (high failure force) combined with less rigidity, ie lower modulus of deformability (MOD) and higher compressibility (high strain and deformation at failure). ‘Red Warren’ had the least firm tissues combined with high rigidity and low compressibility. The firmness of ‘Delica’ and ‘CF 4’ tissues was intermediate. The texture parameters such as MOD, failure force, hardness, gumminess and chewiness measured on raw and cooked tissues of the four cultivars showed no significant differences up to 2 months of storage but then decreased (P < 0.05) between 2 and 3 months of storage. The size of the cells and thickness of the parenchyma cell walls among ‘Delica’, ‘CF 2’ and ‘CF 4’ were similar. The greater size of ‘Red Warren’ parenchyma cells, larger intercellular spaces and thinner cell walls appear to account for its lower tissue strength compared with the other cultivars. Copyright © 2004 Society of Chemical Industry