Response of osteoblast-like MG63 cells to TiO2 layer prepared by micro-arc oxidation and electric polarization

Micro-arc oxidation (MAO) is one of the useful surface modifications of titanium implants to improve bioactivity. Also, electric polarization treatment enhances bioactivity of calcium phosphate. The aim of this study was to evaluate the effect of the combination of two surface modifications, micro-arc oxidation (MAO) with electric polarization, on the behavior of osteoblast-like osteosarcoma MG63 cells. MAO-treated materials had a surface geometry that was favored by MG63 cells as determined using scanning electron microscopy and X-ray diffraction; additionally, electric polarization induced surface electric fields, which were measured using thermally stimulated depolarization currents. The results of assays to study cell–material interactions suggest that these two approaches could regulate cell attachment, spreading, proliferation, and differentiation without the addition of other reagents. This new surface modification processes produce materials with a good surface geometry, generate surface electric fields and enhance the osteopromotive ability of osteoblasts.     

Epoxy Networks Modified by a New Class of Oligomeric Silsesquioxanes Bearing Multiple Intramolecular Rings Formed through Si?O?C Bonds

Summary: A new class of silsesquioxane (SSO), containing species with two to nine Si atoms bearing multiple intramolecular rings formed through Si? O? C bonds, was synthesized as a glassy powder. It was characterized by UV‐MALDI‐TOF MS, ²⁹Si NMR and FT IR. Solutions containing different amounts of SSO in the diglycidyl ether of bisphenol A (DGEBA), were homopolymerized in the presence of (4‐dimethylamino)pyridine (DMAP) as initiator, leading to SSO‐modified epoxy networks. SSO species were covalently bonded to the epoxy network without any evidence of phase separation. The SSO addition provoked an increase in the elastic modulus in the glassy state explained by an increase in the cohesive energy density. The SSO addition gave also place to an increase in the intensity of tan δ and a decrease in both the glass transition temperature and the elastic modulus in the rubbery state. This was explained by a decrease in crosslink density associated with the flexibility of SSO structures. DMAP was much more effective than other usual initiators (like benzyldimethylamine, BDMA), in increasing the crosslink density of the resulting epoxy network. This led to high values of the glass transition temperature and the elastic modulus in the rubbery state.

Schematic representation of the chemical structure of the most significant species containing three Si atoms, present in the silsesquioxane.     

Reinforcement Mechanism of Carbon Black (CB) in Natural Rubber Vulcanizates: Relationship Between CB Aggregate and Network Structure and Viscoelastic Properties

Carbon black (CB) aggregates in CB-filled natural rubber (NR) vulcanizate were joined together and formed CB aggregates in the CB region less than 20?phr. It was found that the viscoelastic behavior was related to the hydrodynamic interaction between CB aggregate and NR matrix. In the CB loading region more than 40?phr, CB aggregates formed CB network structure in it. Using the parallel mechanical model of the two phases of a rubber matrix and an immobilized CB/NR interfacial layer excluding a CB phase, it was possible to quantitatively explain the relationship between the viscoelastic behavior of CB network structure.     

Heterogeneity of protein profiles of Helicobacter pylori isolated from individual patients

A standardized neuropsychological test battery was administered to 167 patients with different forms of mild-to-moderate dementia: probable Alzheimer dementia (AD: n = 49), multi-infarct dementia (n = 43), idiopathic Parkinson disease with dementia (n = 35), depressive pseudodementia (n = 26), and progressive supranuclear palsy (n = 14). Results obtained were used (a) to analyze the profiles of cognitive impairment shown by the different dementia groups; (b) to assess the incidence of some neuropsychological patterns that we hypothesized to be more characteristic of AD, in the various groups; and hence (c) to evaluate the reliability of these patterns as diagnostic markers of AD. Four of the patterns investigated were derived from a verbal learning task (Rey's Auditory Verbal Learning test): (1) absence of the primacy effect; (2) tendency to produce intrusion errors during free recall of a word list; (3) absolute decay of memory trace; and (4) tendency to produce false alarms during delayed recognition of the same word list. Two additional patterns were derived from visual-spatial tasks (copying drawings and Raven's Coloured Progressive Matrices): (5) occurrence of the closing-in phenomenon in copying drawings; and (6) tendency to choose globalistic or odd responses in Raven's matrices. Though all the six patterns were somewhat useful for identifying AD patients, no pattern met the criteria of being both highly sensitive and highly specific, which should characterize an ideal marker. In fact, intrusions and false alarms were observed in many AD patients, but also in patients affected by other forms of dementia. The absence of the primacy effect, the closing-in phenomenon, and the absolute decay of memory trace were more specific, but could be observed in only one-third of AD patients. We also computed the number of positive patterns shown by each patient and assumed the presence of two or more patterns as a global index suggestive of a dementia of the Alzheimer type. With this cumulative method, a higher level of sensitivity and specificity was achieved in the identification of AD patients.     

High‐performance polymer‐stabilized blue‐phase LCD with low driving voltage

We have developed a polymer‐stabilized blue‐phase LCD in which the diffraction wavelength of blue‐phase liquid crystal is in the ultraviolet region and which is driven at a low voltage of V₁₀₀ = 27 V. Prototypes of 3.4‐in polymer‐stabilized blue‐phase LCDs were made, which include a highly reliable crystalline oxide semiconductor. We succeeded in fabricating not a test cell but a display having a contrast ratio higher than 1000 : 1 for the first time in the world.     

An approach to the pursuit problem on a heterogeneous multiagent system using reinforcement learning

Cooperation among agents is important for multiagent systems having a shared goal. In this paper, an example of the pursuit problem is studied, in which four hunters collaborate to catch a target. A reinforcement learning algorithm is employed to model how the hunters acquire this cooperative behavior to achieve the task. In order to apply Q-learning, which is one way of reinforcement learning, two kinds of prediction are needed for each hunter agent. One is the location of the other hunter agents and target agent, and the other is the movement direction of the target agent at next time step t. In our treatment we extend the standard problem to systems with heterogeneous agents. One motivation for this is that the target agent and hunter agents have differing abilities. In addition, even though those hunter agents are homogeneous at the beginning of the problem, their abilities become heterogeneous in the learning process. Simulations of this pursuit problem were performed on a continuous action state space, the results of which are displayed, accompanied by a discussion of their outcomes’ dependence upon the initial locations of the hunters and the speeds of the hunters and a target.     

Gastric carcinoma in young adults

Among 47 blood donors tested positive with HCV EIA 2.0 Abbott, 27 (57.4%) also reacted with four ?third-generation' EIAs. The presence of anti-HCV antibodies was confirmed with 3 different immunoblot assays in 16 of 27 sera (34.0%) while 10 samples (21.3%) had indeterminate profile with antibodies usually directed against structural core antigen. Anti-HCV core IgM response was found in 12 of 47 sera (25.5%) and HCV viremia detected by the polymerase chain reaction (PCR) procedure was observed in 15 samples (31.9%). A comparative study of the different markers confirmed a good correlation between a strong antibody response in EIAs and immunoblot assays and the presence of HCV RNA in the serum; only 2 immunoblot indeterminate samples were PCR positive. An association was observed between IgM antibodies against "core' epitopes and HCV RNA carriage: all IgM-positive sera were found positive by PCR. However, the direct detection of viral genome remains the best method for identifying HCV carriers in the blood donor population.     

Tribochemical Reactions and Lubricating Effects of Fluorinated Methanes for Al2O3 Ceramic

It has been found that CF₃CH₂F (HFC-134a) gas is an effective lubricant for several ceramics because of the formation of fluorine-containing tribochemical products. To understand the influence of the molecular structure of fluorine-containing gases on the lubricating characteristics, the lubricating effects and tribochemical reactions of some fluorinated methanes for Al₂O₃ ceramic were studied. X-ray Photoelectron Spectroscopy (XPS) and Time-of-Flight Secondary Ion Mass Spectroscopy (TOF-SIMS) were used to identify the chemical structure of tribochemical products. It was found that the friction and wear of Al₂O₃ ceramic were dependent on the molecular structure of the reacting fluorocarbon gases. The lowest friction was obtained in CH₂F₂. CHF₃ showed the best anti-wear effect. The results of surface analyses indicate that greater amounts of tribochemical products are produced when Al₂O₃ rubs in CH₂F₂ than in CF₄ and CHF₃ gases. C–C/C–H/carbon and AlF₃, which are mainly formed on the sliding surface in CH₂F₂, are responsible for the low friction. The mechanism of tribochemical reactions of the different environmental molecules on the nascent surface of Al₂O₃ was also discussed.     

Production and characterization of a monoclonal antibody against recombinant thermolabile hemolysin and its application to screen for Vibrio parahaemolyticus contamination in raw seafood

Thermolabile hemolysin gene (tlh) is regarded as a species-specific marker for Vibrio parahaemolyticus. To assess the utility of the tlh gene product, thermolabile hemolysin (TLH), as a marker to screen for V. parahaemolyticus-contamination in raw seafood, we generated a monoclonal antibody (MAb) against recombinant TLH and established with an enzyme-linked immunosorbent assay using the MAb (TLH-ELISA). TLH-ELISA testing of broth cultures for 78 V. parahaemolyticus strains showed positive results all around. In contrast, most broth cultures of 53 non-V. parahaemolyticus species tested yielded negative results.We devised a screening method using TLH-ELISA to check for low-level contamination of V. parahaemolyticus in raw seafood within 24 h and evaluated its ability. In testing of V. parahaemolyticus-spiked raw seafood, results suggested that our screening method can detect 100 most-probable-number (MPN) of V. parahaemolyticus/g. Further, on testing 119 commercial raw seafood samples with our screening method, 117 samples were determined to contain less than 100 MPN of V. parahaemolyticus/g. All of the 117 samples were also estimated by the MPN method to contain less than 100 MPN of V. parahaemolyticus/g. Taken together, these results suggest that our screening method using TLH-ELISA is useful to check for low-level (<100 MPN/g) of V. parahaemolyticus in raw seafood.