Comparative tear concentrations of topically applied ciprofloxacin, ofloxacin, and norfloxacin in human eyes

The tear pharmacokinetic profiles of 0.3% ciprofloxacin, 0.3% ofloxacin, and 0.3% norfloxacin ophthalmic solutions after a single drop topically administrations in the eyes of 30 healthy volunteers were evaluated. Tear samples collected at 30, 120, 180, and 240 minutes, were analyzed for drug concentrations by high performance liquid chromatography (HPLC) with fluorometric detection. Topically applied ciprofloxacin, ofloxacin, and norfloxacin achieved the mean tear concentrations (mean +/- SD) of 11.28 +/- 6.98, 6.52 +/- 4.06, and 13.28 +/- 8.78 micrograms/g at 30 min, and then fell to 3.52 +/- 1.30, 4.82 +/- 1.80, and 5.79 +/- 4.80 micrograms/g at 240 min, respectively. Topical norfloxacin achieved mean tear level significantly higher than ofloxacin at 30 min (p = 0.031). There were no statistically significant differences in the mean tear levels of ciprofloxacin versus ofloxacin (at 30, 120, 180, and 240 min), ciprofloxacin versus norfloxacin (at 30, 120, 180, and 240 min) and ofloxacin versus norfloxacin (at 120, 180, and 240 min). However, the mean tear levels, 240 min after dosing ciprofloxacin and norfloxacin, fell to the statistically significant concentrations (p = 0.02 and p = 0.01, respectively). But, it is concluded that concentrations of ciprofloxacin, ofloxacin, and norfloxacin in tears were still significantly greater than the minimum inhibitory concentrations for the most sensitive organisms, 240 min after a single drop application.     

Development of germ tubes in various strains of Candida

57 different Candida strains are studied and it is observed that most of them developed germ tubes.     

Hierarchical modeling of availability in distributed systems

Distributed computing systems are attractive due to the potential improvement in availability, fault-tolerance, performance, and resource sharing. Modeling and evaluation of such computing systems is an important step in the design process of distributed systems. We present a two-level hierarchical model to analyze the availability of distributed systems. At the higher level (user level), the availability of the tasks (processes) is analyzed using a graph-based approach. At the lower level (component level), detailed Markov models are developed to analyze the component availabilities. These models take into account the hardware/software failures, congestion and collisions in communication links, allocation of resources, and the redundancy level. A systematic approach is developed to apply the two-level hierarchical model to evaluate the availability of the processes and the services provided by a distributed computing environment. This approach is then applied to analyze some of the distributed processes of a real distributed system, Unified Workstation Environment (UWE), that is currently being implemented at AT&T Bell Laboratories     

Synchronous optical network and broadband ISDN protocols

High-level technical information on Sonet (synchronous optical network) B-ISDN (broadband integrated services digital network) protocols, and interface structures is provided. Since the B-ISDN protocol standards to be used in the Broadband Reference Model are currently being discussed in the CCITT, most of the standards are not yet available. Therefore, some of the protocols described here are not based on agreements reached in national and international standards bodies. The discussion covers B-ISDN architecture and the ISO model. Sonet protocols and architecture, B-ISDN configuration, and the ATM (asynchronous transfer model) architecture     

Annealing and light effect on optical and electrical properties of ZnS thin films grown with the SILAR method

Zinc sulphide (ZnS) thin films were grown on glass substrates by the Successive Ionic Layer Adsorption and Reaction (SILAR) technique at room temperature and ambient pressure. Surface morphologies of grown films were characterized using scanning electron microscopy (SEM). The crystal structure and crystal size of the thin films were characterized by the X-ray diffraction (XRD) method and found that the films exhibit polycrystalline characterization. The optical absorption measurements were done as a function of the temperature at 10–320 K temperature range. Using absorption measurements, the band gap energies were calculated at 10 and 320 K, as 3.83 and 3.72 eV, respectively. The annealing temperature effect on optical band gap and the light effect on the electrical properties of ZnS thin films were investigated and it was found that the current increased with increasing light intensity. The annealed films were found have more resistance than the as-grown film.     

Vitamin C hinders radiation cross-linking in aqueous poly(vinyl alcohol) solutions

Poly(vinyl alcohol) (PVA) is a promising semi-crystalline material for biomedical applications. It is soluble in water and can be formed into hydrogels by freezing and thawing or crystallizing from an aqueous theta solution such as that of polyethylene glycol (PEG). Radiation cross-linking caused by sterilization or high dose irradiation of concentrated PVA solutions could compromise some properties of these hydrogels. Therefore, we hypothesized that radiation cross-linking of PVA solutions and PVA-PEG theta gels could be prevented by using the antioxidant vitamin C as an anticross-linking agent. Our hypothesis tested positive. Vitamin C concentrations of 0.75 and 4.5 mol/mol of PVA repeating unit could prevent cross-linking in 17.5 wt/v% PVA solutions made with PVA molecular weight of 115,000 g/mol irradiated to 25 and 100 kGy, respectively. Vitamin C also prevented cross-linking in 25 kGy irradiated PVA-PEG theta gels containing up to 5 wt% PEG and decreased the viscosity of those up to 39 wt%.     

Dynamic Predication of Indirect Jumps

Indirect jumps are used to implement increasingly-common programming language constructs such as virtual function calls, switch-case statements, jump tables, and interface calls. Unfortunately, the prediction accuracy of indirect jumps has remained low because many indirect jumps have multiple targets that are difficult to predict even with specialized hardware. This paper proposes a new way of handling hard-to-predict indirect jumps: dynamically predicating them. The compiler identifies indirect jumps that are suitable for predication along with their control-flow merge (CFM) points. The microarchitecture predicates the instructions between different targets of the jump and its CFM point if the jump turns out to be hard-to-predict at run time. We describe the new indirect jump predication architecture, provide code examples showing why it could reduce the performance impact of jumps, derive an analytical cost-benefit model for deciding which jumps and targets to predicate, and present preliminary evaluation results.     

Differential Responses to Bioink-Induced Oxidative Stress in Endothelial Cells and Fibroblasts

A hydrogel system based on oxidized alginate covalently crosslinked with gelatin (ADA-GEL) has been utilized for different biofabrication approaches to design constructs, in which cell growth, proliferation and migration have been observed. However, cell–bioink interactions are not completely understood and the potential effects of free aldehyde groups on the living cells have not been investigated. In this study, alginate, ADA and ADA-GEL were characterized via FTIR and NMR, and their effect on cell viability was investigated. In the tested cell lines, there was a concentration-dependent effect of oxidation degree on cell viability, with the strongest cytotoxicity observed after 72 h of culture. Subsequently, primary human cells, namely fibroblasts and endothelial cells (ECs) were grown in ADA and ADA-GEL hydrogels to investigate the molecular effects of oxidized material. In ADA, an extremely strong ROS generation resulting in a rapid depletion of cellular thiols was observed in ECs, leading to rapid necrotic cell death. In contrast, less pronounced cytotoxic effects of ADA were noted on human fibroblasts. Human fibroblasts had higher cellular thiol content than primary ECs and entered apoptosis under strong oxidative stress. The presence of gelatin in the hydrogel improved the primary cell survival, likely by reducing the oxidative stress via binding to the CHO groups. Consequently, ADA-GEL was better tolerated than ADA alone. Fibroblasts were able to survive the oxidative stress in ADA-GEL and re-entered the proliferative phase. To the best of our knowledge, this is the first report that shows in detail the relationship between oxidative stress-induced intracellular processes and alginate di-aldehyde-based bioinks.     

Surface‐Reactive Patchy Nanoparticles and Nanodiscs Prepared by Tandem Nanoprecipitation and Internal Phase Separation

Nanoparticles with structural or chemical anisotropy are promising materials in domains as diverse as cellular delivery, photonic materials, or interfacial engineering. The surface chemistry may play a major role in some of these contexts. Introducing reactivity into such polymeric nanomaterials is thus of great potential, yet is still a concept in its infancy. In the current contribution, a simple nanoprecipitation technique leads to nanoparticles with diameters as low as 150 nm and well‐defined reactive surface patches of less than 30 nm in width, as well as surface‐reactive flat, disc‐like nanoparticles with corresponding dimensions, via an additional crosslinking/delamination sequence. To this aim, chemically doped block copolymers (BCPs) are employed. Control over morphology is attained by tuning preparation conditions, such as polymer concentration, solvent mixture composition, and blending with non‐functional BCP. Surface reactivity is demonstrated using a modular ligation method for the site‐selective immobilization of thiol molecules. The current approach constitutes a straightforward methodology requiring minimal engineering to produce nanoparticles with confined surface reactivity and/or shape anisotropy.     

A Subtractive Photoresist Platform for Micro‐ and Macroscopic 3D Printed Structures

The selective removal of structural elements plays a decisive role in 3D printing applications enabling complex geometries. To date, the fabrication of complex structures on the microscale is severely limited by multistep processes. Herein, a subtractive photoresist platform technology that is transferable from microscopic 3D printing via direct laser writing to macroscopic structures via stereolithography is reported. All resist components are readily accessible and exchangeable, offering fast adaptation of the resist's property profile. The micro‐ and macroprinted structures can be removed in a facile fashion, without affecting objects based on standard photoresists. The cleavage is analyzed by time‐lapse optical microscopy as well as via in‐depth spectroscopic assessment. The mechanical properties of the printed materials are investigated by nanoindentation. Critically, the power of the subtractive resist platform is demonstrated by constructing complex 3D objects with flying features on the microscale.