Size controlled synthesis of biocompatible gold nanoparticles and their activity in the oxidation of NADH

Size and shape controlled synthesis remains a major bottleneck in the research on nanoparticles even after the development of different methods for their preparation. By tuning the size and shape of a nanoparticle, the intrinsic properties of the nanoparticle can be controlled leading tremendous potential applications in different fields of science and technology. We describe a facile route for the one pot synthesis of gold nanoparticles in water using monosodium glutamate as the reducing and stabilizing agent in the absence of seed particles. The particle diameter can be easily controlled by varying the pH of the reaction medium. Nanoparticles were characterized using scanning electron microscopy, UV-vis absorption spectroscopy, cyclic voltammetry, and dynamic light scattering. Zeta potential measurements were made to compare the stability of the different nanoparticles. The results suggest that lower pH favours a nucleation rate giving rise to smaller particles and higher pH favours a growth rate leading to the formation of larger particles. The synthesized nanoparticles are found to be stable and biocompatible. The nanoparticles synthesized at high pH exhibited a good electrocatalytic activity towards oxidation of nicotinamide adenine dinucleotide (NADH).     

Differential nano-bio interactions and toxicity effects of pristine versus functionalized graphene

We report the effect of carboxyl functionalization of graphene in pacifying its strong hydrophobic interaction with cells and associated toxic effects. Pristine graphene was found to accumulate on the cell membrane causing high oxidative stress leading to apoptosis, whereas carboxyl functionalized hydrophilic graphene was internalized by the cells without causing any toxicity.     

Phytofiltration of cadmium from water by Limnocharis flava (L.) Buchenau grown in free-floating culture system

A hydroponics experiment was conducted to examine the phytofiltration of Cd by Limnocharis flava (L.) Buchenau grown in low-level Cd-contaminated water. For this, 45 d old seedlings of L .flava were transferred to a floating-support culture system containing nutrient solution spiked with four levels of Cd (0.5, 1, 2 and 4 mg l⁻¹) and were separately harvested after 3, 7, 21 and 30 d. After 30 d harvesting, the percentage removal of Cd from the above four treatments reached up to 98, 96, 95 and 93%, respectively. Interestingly, all treatments had higher growth rate than control at 95% confidence level and plants still remained healthy at 4 mg l⁻¹ Cd exposure. The bioaccumulation study showed a linear relationship of Cd (R² = 0.896–0.999) in all plant parts with the exposure time (3–30 d) and Cd concentrations in hydroponics system (0.5–4 mg l⁻¹). Although, the root of L. flava had higher Cd concentration than leaf and peduncles, the total Cd concentrations in aerial plant parts were higher than the roots. The maximum bioconcentration factor (BCF) and translocation factor (TF) value of L. flava were calculated as 984.42 and 1.43, respectively. Estimated Cd accumulation capacity of L. flava per unit area (m²) was found to be in the range of 218. 35–1698.92 mg m⁻².The experimental results demonstrated that L. flava is a suitable candidate for the phytofiltartion (>93%) of Cd from low-level Cd-contaminated water.     

A comparative study of the tensile properties of compression molded and 3D printed PLA specimens in dry and water saturated conditions

Journal of Mechanical Science and Technology - This research work presents a comparative study of the tensile properties of polylactic acid (PLA) specimens per ASTM D638-14 fabricated by...     

Bidirectional Optical Interconnection at Gb/s Data Rates With Monolithically Integrated VCSEL-MSM Transceiver Chips

We present the operation characteristics of 850-nm wavelength GaAs-based monolithically integrated transceiver chips designed for low-cost short-distance bidirectional optical data transmission over a butt-coupled 200-mum core diameter polymer-clad silica fiber. The chips containing a vertical-cavity surface-emitting laser and a large-area metal-semiconductor-metal photodiode can well handle data rates of 2.5Gb/s in back-to-back mode and 0.5 Gb/s for 10-m fiber length     

Parallel computational geometry of rectangles

Rectangles in a plane provide a very useful abstraction for a number of problems in diverse fields. In this paper we consider the problem of computing geometric properties of a set of rectangles in the plane. We give parallel algorithms for a number of problems usingn processors wheren is the number of upright rectangles. Specifically, we present algorithms for computing the area, perimeter, eccentricity, and moment of inertia of the region covered by the rectangles inO(logn) time. We also present algorithms for computing the maximum clique and connected components of the rectangles inO(logn) time. Finally, we give algorithms for finding the entire contour of the rectangles and the medial axis representation of a givenn × n binary image inO(n) time. Our results are faster than previous results and optimal (to within a constant factor).The work of Sung Kwan Kim was supported by NSF Grant CCR-87-03196 and the work of D. M. Mount was partially supported by National Science Foundation Grant CCR-89-08901.     

Agyria-pachygyria and agenesis of the corpus callosum: autosomal recessive inheritance with neonatal death

We report three neonates, one boy and two girls, born to an inbred Arab family who had cortical dysplasia, probably agyria-pachygyria, and agenesis of the corpus callosum. All had asphyxia, intractable seizures, and increased muscle tone at birth and died in the neonatal period. Congenital microcephaly or dysmorphic features were absent. Cytogenetic abnormality, metabolic disorder, and intrauterine infection were excluded. These cases suggest a new cerebral dysgenesis syndrome with autosomal recessive inheritance.     

Can Diastat Grafts Meet the Challenges of Daily Punctures?

To determine whether Diastat grafts can meet the challenges of daily needle punctures required for home hemodialysis (HD), a retrospective analysis was performed on the experience with 47 grafts placed in 44 patients receiving HD three times a week. The control group consisted of 17 patients who received 17 stretch polytetrafluoroethylene (s-PTFE) grafts. Apart from their ability to better contain bleeding after needle withdrawal, in all measures of longevity the Diastat grafts were outperformed by the s-PTFE grafts. No more direct data exist to address the original challenge.     

Multiple token‐based neighbor discovery for directional sensor networks

Directional sensor networks (DSNs) can significantly improve the performance of a network by employing energy efficient communication protocols. Neighbor discovery is a vital part of medium access control (MAC) and routing protocol, which influences the establishment of communication between neighboring nodes. Neighbor discovery is a challenging task in DSNs due to the limited coverage provided by directional antennas. Furthermore, in these networks, communication can only take place when the beams of the directional antennas are pointed toward each other. In this article, we propose a novel multiple token‐based neighbor discovery (MuND) protocol, in which multiple tokens are transmitted based on an area exploration algorithm. The performance of the protocol is evaluated using the Cooja simulator. The simulation results reveal that the proposed MuND protocol achieves lower neighbor discovery latency, with a 100% neighbor discovery ratio, and has a relatively low communication overhead and low energy consumption.     

Innovation systems in Malaysia: a perspective of university—industry R&D collaboration

Collaborative research and development (R&D) activities between public universities and industry are of importance for the sustainable development of the innovation ecosystem. However, policymakers especially in developing countries show little knowledge on the issues. In this paper, we analyse the level of university–industry collaboration in Malaysia. We further examine the fundamental conditions that hinder university–industry collaboration despite the government’s initiatives to improve such linkages. We show that the low collaboration  is a result of an R&D gap between the entities. While the universities engage in basic and fundamental R&D, the private sectors involved in incremental innovation that requires less R&D investments. The different nature of the industries’ R&D requires closer cooperation between firms namely buyers, suppliers and technical service providers and not the universities. Among others, the lack of an intermediary role, absorptive capacity and collaborative initiative by the industry also contribute to the problem. The study suggests that the collaborative activities can benefit both if deliberate and effective efforts on reducing the R&D mismatch are made between the universities and industry. Likewise, proper institutional arrangements in coordinating these activities are required. This result seems to reflect the nature of many developing countries’ national innovation systems, and therefore, lessons from Malaysia may serve as a good case study.