Antibacterial and Antibiofilm Activity of Mercaptophenol Functionalized-Gold Nanorods Against a Clinical Isolate of Methicillin-Resistant Staphylococcus aureus

Journal of Inorganic and Organometallic Polymers and Materials - Gold nanorods (AuNRs) were synthesized by the seed-mediated wet chemical method using a binary surfactant system. AuNRs were...     

Chemical Synthesis,Sintering and Piezoelectric Properties of Ba0.85Ca0.15 Zr0.1Ti0.9O3 Lead‐Free Ceramics

The preparation of Ba_0.85Ca_0.15 Zr_0.1Ti_0.9O₃ (BCZT) powders by wet chemical methods has been investigated, and the powders used to explore relationships between the microstructure and piezoelectric properties (d₃₃ coefficient) of sintered BCZT ceramics. Sol–gel synthesis has been shown to be a successful method for the preparation of BCZT nanopowders with a pure tetragonal perovskite phase structure, specific surface area up to 21.8 m²/g and a mean particle size of 48 nm. These powders were suitable for the fabrication of dense BCZT ceramics with fine‐grain microstructures. The ceramics with the highest density of 95% theoretical density (TD) and grain size of 1.3 μm were prepared by uniaxial pressing followed by a two‐step sintering approach which contributed to the refinement of the BCTZ microstructure. A decrease in the grain size to 0.8–0.9 μm was achieved when samples were prepared using cold isostatic pressing. Using various sintering schedules, BCZT ceramics with broad range of grain sizes (0.8–60.5 μm) were prepared. The highest d₃₃ = 410.8 ± 13.2 pC/N was exhibited by ceramics prepared from sol–gel powder sintered at 1425°C, with the relative density of 89.6%TD and grain size of 36 μm.     

New binary thermoresponsive polymeric system for local chemoradiotherapy

Radiolabeled thermoresponsive polymers (TRPs) with cloud‐point temperatures between room temperature and body temperature may have an advantage for local radiotherapeutical applications because TRPs may be isotopically labeled in solution at room temperature and injected as a solution, and at the site of application, the polymers form a depo because of phase separation at body temperature. A new polymeric drug‐delivery system designed for combined local chemoradiotherapy with an injectable TRP bearing a radionuclide and the hydrophobic moiety doxorubicin (DOX) was synthesized and characterized. In the system, DOX served as an antiproliferative agent with known synergic effects with ionizing radiation and the hydrophobic moiety controlling bioerosion and elimination of the system at the same time. DOX was bound to the polymer carrier by a hydrolytically labile N‐glycosylamine bond. Hydrolysis of the N‐glycosylamine bond thus controlled the DOX release and dissolution of the system in the model aqueous milieu. DOX was slowly released during incubation in aqueous milieu at 37°C, which caused complete dissolution of the bioerodable polymer within about 2 weeks. The model radionuclide iodine 125, bound to a small amount of poly(N‐isopropylacrylamide‐co‐N‐methacryloyl tyrosinamide), was retained in the separated phase and also slowly dissolved during the incubation. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Characterization of alkylphenol degradation gene cluster in Pseudomonas putida MT4 and evidence of oxidation of alkylphenols and alkylcatechols with medium-length alkyl chain

Alkylphenols (APs) are ubiquitous contaminants in aquatic environments and have endocrine disrupting and toxic effects on aquatic organisms. To investigate biodegradation mechanisms of APs, an AP degradation gene cluster was cloned from a butylphenol (BP)-degrading bacterium, Pseudomonas putida MT4. The gene cluster consisted of 13 genes named bupBA1A2A3A4A5A6CEHIFG. From the nucleotide sequences, bupA1A2A3A4A5A6 were predicted to encode a multicomponent phenol hydroxylase (PH), whereas bupBCEHIFG were expected to encode meta-cleavage pathway enzymes. A partial sequence of a putative NtrC-type regulatory gene, bupR, was also found upstream of the gene bupB. This result indicates that APs can be initially oxidized into alkylcatechols (ACs), followed by the meta-cleavage of the aromatic rings. To confirm this pathway, AP degradation tests were carried out using the recombinant P. putida KT2440 harboring the PH genes (bupA1A2A3A4A5A6). The recombinant strain oxidized 4-n-APs with an alkyl chain of up to C7 (< or = C7) efficiently and also several BPs including those with an alkyl chain with some degree of branching. Therefore, it was found that PH had a broad substrate specificity for APs with a medium-length alkyl chain (C3-C7). Moreover, the cell extract of a recombinant Escherichia coli harboring bupB (a catechol 2,3-dioxygenase gene) converted 4-n-ACs with an alkyl chain of < or = C9 into yellow meta-cleavage products with a maximum absorbance at 379 nm, indicating that the second step enzyme in this pathway is also responsible for the degradation of ACs with a medium-length alkyl chain. These results suggest that MT4 is a very useful strain in the biodegradation of a wide range of APs with a medium-length alkyl chain, which known nonylphenol-degrading Sphingomonas strains have never degraded.     

Influence of electric field on the ultrasound velocity in PZT ceramics

The paper deals with the influence of the electric bias field on the ultrasound velocity of various samples of Pb(Zr _x Ti_1−x )O₃ (PZT) ceramics. The ultrasonic velocities were measured on commercial types of PZT ceramics as APC 841, APC 850, and APC 856, at room temperature. The comparison of the ultrasound velocities dependence on electric bias field was made for poled/unpoled soft ceramics. The ultrasonic pulse-echo technique was used in our experiment. The ultrasonic system is based on Matec Instruments, Inc. modules. The time domain response was recorded and time of flight between echoes was directly measured by digital oscilloscope, type Agilent 54622D. The high bias field was applied on disk samples by the high voltage amplifier type Trek 610D, using a special setup and sample holder. The sound velocity was found to change drastically near the coercive field for a PZT ceramics, where the velocity of longitudinal waves decreases with an increasing field while the velocity of shear waves increases, which is caused by the change of the elastic anisotropy under influence of the depolarization field. The consequent change of the piezoelectric contribution to effective elastic constant decreases the velocity of longitudinal waves and at the same time increases the velocity of shear waves around the coercive field.     

Accessibility and findability of local e-government websites in the Czech Republic

This article focuses on the accessibility of local e-government web pages. Accessibility is herein considered in a broader perspective, taking also into account that information must be findable within the Internet through conventional fulltext search engines. Based on this assumption, an analysis of 39 local e-government websites in the Czech Republic was carried out in two testing periods (March 2006 and April 2008). The web pages were analysed both from a citizen’s point of view (with disadvantage due to disability or to technical equipment) and from the point of view of fulltext search engines. In the analysis of results, there is an overall evaluation and comparison between testing periods and recommendations for improvement of the current conditions.     

Photoelectrochemical and photocatalytic properties of titanium (IV) oxide nanoparticulate layers

Titania nanostructured particles were produced by the sol-gel method in the reverse micelle environment treated thermally and by various extraction steps including supercritical carbon dioxide, subcritical water and their combinations. Thin films comprised of the organized nanoparticles were tested in photoelectrochemical and photocatalytic experiments. The former were configured for the open circuit potential measurements and evaluation of polarization curves and the corresponding photocurrents. Photocatalytic activities of the layered films were assessed by following decomposition of the methyl ester of stearic acid. Attention was also paid to evaluation of the extent of the surface wettability of the layers. The effect of content of residual surface carbon, extent of hydrophilic properties and presence of anatase structure were identified as essential parameters responsible for the enhanced photoactivity of the tested layers. On the other hand also layers treated without any thermal steps revealed certain level of photoactivity that might be of special importance in some specific applications.     

Automatic Verification of Fault-Tolerant Register Emulations

The design and verification of fault-tolerant distributed algorithms is a complicated task. Usually, the proof of correctness is done manually, and thus depends on the skill of the prover. Using automated verification methods, such as model checking, can greatly simplify the verification. However, model checking of distributed algorithms is often intractable because of the state-explosion problem. In this paper we present a novel approach to verification of quorum-based distributed register emulation algorithms with undetectable crash failures of processes. Our approach is based on projection and abstraction and allows us to reduce the task of model-checking the whole system to fair model-checking of subsystems consisting of a constant number of processes. Our method is highly scalable and can be applied to a large class of algorithms. Aside from efficient verification, it can also be used for finding redundancies in existing algorithms.     

Effect of maternal dietary vitamin C intake on the level of vitamin C in breastmilk among nursing mothers in Baghdad,Iraq

The vitamin C content of breastmilk was investigated in a group of nursing mothers attending maternal and child health centers in Baghdad during 1998-2000. Two hundred healthy, nonsmoking, 28- to 38-year-old lactating women were studied. Individual samples of breastmilk were obtained for estimation of vitamin C. Dietary data were collected by using 24-hour food recalls. The mean intake of vitamin C was far below the Food and Agriculture Organization/World Health Organization requirement of 26 +/- 2.13 (SD) mg/day). The vitamin C content of breastmilk was significantly correlated with the maternal intake of vitamin C (r = 0.61, p < .01). The vitamin C content of breastmilk varied with the season. The level was much higher in summer (3.9 +/- 1.05 mg/100 ml) than in winter (3.02 +/- 2.01 mg/100 ml; p < .05). This fluctuation indicates the dependence of breastmilk vitamin C on dietary intake. The results show the need to increase the consumption of vegetables and fruits and to monitor maternal ascorbic acid intake.     

Aligned nanofibres made of poly(3-hydroxybutyrate) grafted to hyaluronan for potential healthcare applications

In this work, a hybrid copolymer consisting of poly(3-hydroxybutyrate) grafted to hyaluronic acid (HA) was synthesised and characterised. Once formed, the P(3HB)-g-HA copolymer was soluble in water allowing a green electrospinning process. The diameters of nanofibres can be tailored by simply varying the M_w of polymer. The optimization of the process allowed to produce fibres of average diameter in the range of 100–150?nm and low polydispersity. The hydrophobic modification has not only increased the fibre diameter, but also the obtained layers were homogenous. At the nanoscale, the hybrid copolymer exhibited an unusual hairy topography. Moreover, the hardness and tensile properties of the hybrid were found to be superior compared to fibres made of unmodified HA. Particularly, this reinforcement was achieved at the longitudinal direction. Additionally, this work reports the use in the composition of a water-soluble copolymer containing photo cross-linkable moieties to produce insoluble materials post-electrospinning. The derivatives as well as their nanofibrous mats retain the biocompatibility of the natural polymers used for the fabrication.

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