A Monte Carlo simulation study of the mechanical and conformational properties of networks of helical polymers. I. General concepts

We study the mechanical and conformational properties of networks of helical polymers with a combination of Monte Carlo simulations based on the Wang-Landau algorithm and the three-chain model. We find that the stress-strain behavior of these networks has novel features not observed in typical networks made of synthetic polymers. In particular, we find that as these networks are stretched they first strengthen, then soften and finally strengthen again. This non-monotonic behavior of the stress correlates with the one of the helical content and is rationalized by the elongation-induced formation and melting of the helical structure of the polymer. We complement these results with a study of other conformational properties of the polymer strands that clarify the molecular mechanisms behind the mechanical behavior of these networks. Finally, we present a qualitative comparison of some of our results with the theoretical ones recently reported by Kutter and Terentjev.     

Synthesis and Biological Characterization of (3R,4R)‐4‐(2‐(Benzhydryloxy)ethyl)‐1‐((R)‐2‐hydroxy‐2‐phenylethyl)‐piperidin‐3‐ol and Its Stereoisomers for Activity toward Monoamine Transporters

A novel series of optically active molecules based on a 4‐(2‐(benzhydryloxy)ethyl)‐1‐((R)‐2‐hydroxy‐2‐phenylethyl)‐piperidin‐3‐ol template were developed. Depending on stereochemistry, the compounds exhibit various degrees of affinity for three dopamine, serotonin, and norepinephrine transporters. These molecules have the potential for treating several neurological disorders such as drug abuse, depression, and attention deficit hyperactivity disorder.

     

Design and analysis of fuzzy morphological algorithms for imageprocessing

A general paradigm for lifting binary morphological algorithms to fuzzy algorithms is employed to construct fuzzy versions of classical binary morphological operations. The lifting procedure is based upon an epistemological interpretation of both image and filter fuzzification. Algorithms are designed via the paradigm for various fuzzifications and their performances are analyzed to provide insight into the kind of liftings that produce suitable results. Algorithms are discussed for three image processing tasks: shape detection, edge detection, and clutter removal. Detailed analyses are given for the effect of noise and its mitigation owing to fuzzy approaches. It is demonstrated how the fuzzy hit-or-miss transform can be used in conjunction with a decision procedure to achieve word recognition     

Changes in anterior chamber depth and intraocular pressure after phacoemulsification and posterior chamber intraocular lens implantation

BACKGROUND AND OBJECTIVE: To determine anterior chamber depth (ACD) and intraocular pressure (IOP) following uncomplicated cataract extraction with phacoemulsification and posterior chamber intraocular lens (IOL) implantation. PATIENTS AND METHODS: The ACDs and IOPs of 56 patients were prospectively evaluated after phacoemulsification and IOL implantation. Measurements of ACD were performed using ultrasonography and measurements of IOP were performed using a Goldmann applanation tonometer preoperatively and at 1 week and 1, 3, 6, and 9 months postoperatively. RESULTS: The mean IOP had decreased and the mean ACD had increased significantly by 1 month postoperatively (P < .03 and P < .01, respectively). Between 1 and 3 months, a significant increase in ACD (P < .05) and decrease in IOP (P < .01) was also observed. The ACD peaked (3.51 +/- 0.45 mm) and the IOP reached its lowest value (10.05 +/- 2.23 mm Hg) at 3 months postoperatively. The reduction in IOP and increase in ACD remained significant during the follow-up period, compared with the preoperative values. CONCLUSION: These results suggest that increases in ACD and decreases in IOP occur in selected patients after uncomplicated cataract extraction by phacoemulsification with IOL implantation.     

The use of perfluorodecalin in retinal detachments with retinoschisis

BACKGROUND AND OBJECTIVE: To evaluate the effect of perfluorodecalin on the repair of retinal detachments with retinoschisis. PATIENTS AND METHODS: Twenty-two eyes of 20 patients with degenerative and X-linked retinoschisis underwent pars plana vitrectomy, perfluorodecalin injection, internal fluid drainage, and fluid-air exchange. RESULTS: The retina was reattached intraoperatively in 21 (95.4%) of the 22 eyes. In 4 eyes, retinal detachment recurred within 2 months postoperatively. All of the recurrent cases underwent reoperation with perfluoropropane gas and the retina was reattached at the end of 2 operations. As a result, visual acuity increased in 18 (81.8%) of the 22 eyes. CONCLUSION: Perfluorodecalin makes flattening of the retina and evacuation of subretinal fluid easier in the management of rhegmatogenous retinal detachments associated with degenerative and X-linked retinoschisis.     

Comparison of aqueous humour and vitreous humour levels of two 0.3% ciprofloxacin eyedrops

BACKGROUND: Two ophthalmic solutions of 0.3% ciprofloxacin eyedrops are available in Turkey: Ciloxan and Siprogut. The objective of this study was to compare the concentrations of drug produced by the two products in the aqueous humour and vitreous humour after local administration. METHODS: Twenty-one patients undergoing primary vitreoretinal surgery received either Ciloxan (10 patients) or Siprogut (11 patients). Six hours before surgery, two drops of solution were instilled onto the operative eye. Drops were then instilled every 30 minutes for the first 3 hours and then hourly for the next 3 hours. Aqueous and vitreous samples were collected 30 minutes after administration of the last dose and were assayed for ciprofloxacin concentration by means of high-performance liquid chromatography with fluorometric detection. RESULTS: The mean aqueous humour concentrations of Ciloxan and Siprogut were 0.36 (standard error of the mean [SEM] 0.09) microgram/mL and 0.44 (SEM 0.17) microgram/mL respectively. The corresponding vitreous humour concentrations were 0.21 (SEM 0.05) microgram/mL and 0.22 (SEM 0.06) microgram/mL. Neither of these differences was statistically significant. The aqueous and vitreous levels of both products exceeded the minimum inhibitory concentrations for certain bacterial species that frequently cause intraocular infections. INTERPRETATION: Our results show that the ocular bioavailability of Ciloxan and Siprogut after local administration is equivalent. Penetration of ciprofloxacin into the vitreous humour seems to be poorer than that into the aqueous humour.     

The knowledge and practice of food safety and hygiene of cookery students in Turkey

The aim of this study was to assess the knowledge and practice of food safety and hygiene among students in university cookery programs in Turkey. A questionnaire was given to 82 cookery students in two vocational schools from two different universities. The results showed that although the students regarded the issues of food safety and personal hygiene as important, they had inadequate knowledge in these areas.     

HIV enteropathy: comparative morphometry of the jejunal mucosa of HIV infected patients resident in the United Kingdom and Uganda

The substructure and responses of individual 100-nm synaptic vesicles to osmotic stress have been probed with an atomic force microscope (AFM) operating in tapping mode. Cholinergic synaptic vesicles from the electric organ of Torpedo californica were imaged continuously as the osmolarity of the buffer was decreased. Vesicles in hyposmotic buffer lysed to form flat circular structures on the mica surface with a diameter about two times that of intact vesicles and a thickness of 7.2 +/- 1.7 nm, which can accommodate the lipid bilayer plus the internal proteoglycan. Images of intact vesicles in air reveal creases in the membrane surface. Phase mode AFM images of lysed vesicles in air show the presence of a material not seen on intact vesicles that might be intravesicular proteoglycan released from the membrane at very low osmotic and ionic strength.