The use of life cycle tools to support decision making for sustainable nanotechnologies

Nanotechnology is a broad-impact technology with applications ranging from materials and electronics to analytical methods and metrology. The many benefits that can be realized through the utilization of nanotechnology are intended to lead to an improved quality of life. However, numerous concerns have been expressed regarding the unchecked growth of nanotechnology and the unforeseen consequences it may bring. To address the concerns, nanotechnology must be examined under the microscope of sustainability. This work applies the life cycle perspective to provide an understanding of the challenges facing the development of sustainable nanotechnology. A discussion of the holistic tools used to assess the components of sustainability serves as the basis to examine how a harmony between policy and product development can be maintained using decision making for sustainability. This harmony will be most readily achieved using an enhanced risk management strategy for sustainability that combines sustainability assessment with sustainable chemical design.     

PREDICTION OF JAPANESE ENCEPHALITIS VECTORS IN KURNOOL DISTRICT OF ANDHRA PRADESH,INDIA BY USING BAYESIAN NETWORK

Japanese encephalitis (JE), a complex viral disease transmitted by mosquitoes. Determination of vector (mosquito) density is a prerequisite for devising effective control measures against this disease. Bayesian network is a widely used tool that has recently found application in the epidemiological surveillance studies. This article describes the application of Bayesian network tool to predict the Japanese encephalitis vector density using the longitudinal data collected from the Kurnool district of Andhra Pradesh, India, from 2001 to 2006. The entomological parameter from the study area indicates that various contributing factors are responsible for the prevalence of these vectors, making it difficult to estimate the importance of any particular parameter contributing to the increase of vector density. The application of this approach resulted in 73.12% to 95.12% accuracy compared to the test data with the corrected data.     

Wide-band GaInAs MISFET amplifiers

The authors present the first reported results on wideband GaInAs MISFET amplifiers. Using 1-μm-gate-length, 0.56-mm-gate-width GaInAs MISFETs, they obtained: (a) a power output of 230±30 mW (0.41 W/mm) with 33±3% power-added efficiency; (b) a power output of 265±15 mW (0.47 W/mm) with 30±3% power-added efficiency (both over the 7-11-GHz band), and (c) a power output of 220±45 mW (0.39 W/mm) with 32±4% power-added efficiency over the 6-12-GHz band. With a 0.7-μm-gate-length GaInAs MISFET, a small-signal gain of 5±0.5 dB over the 11.4-22.6-GHz band was obtained. These data include all connector, bias network, and circuit losses. The authors present an equivalent circuit model of these MISFETs based on S-parameter measurements. The model is essentially that of a MISFET with capacitors representing gate-to-source and gate-to-drain overlap capacitances added at input and output     

High-fidelity lightwave transmission of multiple AM-VSB NTSCsignals

The progress towards developing AM lightwave links for the transmission of multiple TV signals is reported. While the signal-quality objectives and transmission distances are appropriate for CATV trunking, the technology is expected to have applicability to the distribution of video signals in the subscriber loop. Highly linear 1.3-μm distributed feedback (DFB) lasers designed expressly for analog requirements are used to transmit 42 continuous wave carriers according to the standard US CATV frequency plan. For the best lasers, when evaluated over 12 km of fiber, carrier to noise was >52 dB, composite second-order distortion was >70 dBc, and composite triple beat was >70 dBc. The relationship between measurements with continuous wave carriers and actual video signals is discussed. System design rules are offered. Properties that lead to superior analog performance are discussed. Data from 700 links indicate that composite third-order distortion generally scales with product count but that composite second-order distortion has a significant frequency-dependent component     

Alkylation of benzene with isopropanol over SAPO‐5: A kinetic study

The kinetics of benzene alkylation with isopropanol has been studied in vapour phase over SAPO‐5 catalyst. On the basis of the product distribution pattern obtained over this large pore molecular sieve, a reaction mechanism has been proposed. Based on this reaction network, suitable phenomenological models have been derived and fitted to the kinetic data. A Langmuir‐Hinshelwood model with surface reaction involving single site mechanism fitted the data better than the other models. The deactivation kinetics has also been investigated in the low temperature chosen. The activation energy for the deactivation reaction in this range is found to be lower than that for the main reaction.     

Why do Firms Locate Across Multiple Clusters? Cluster Density,Capabilities and Ethnic Ties

It is well-accepted that firms locate in clusters to benefit from spillover effects from similar firms in the location. However, some firms choose to locate in multiple clusters. In this paper, we focus on the phenomenon of multi-cluster presence. Through an empirical investigation of 95 firms from the information technology enabled service industry within India, we analyze the drivers of membership across multiple clusters. Our findings indicate first that firms that are located in lower density clusters show a tendency to locate in a larger number of clusters. Second, firms that are looking for people-based creative capabilities also tend to locate in a larger number of clusters. Finally, the firms that are not founded at the location of ethnic origin of the founder CEO also tend to locate in a larger number of clusters.     

Quasienhancement-mode operation of transferred-electron logic devices (t.e.l.d.s)

A new mode of operation is discussed for transferred-electron logic devices. In the new mode, the device dissipation can be cut down considerably. Also, the stability of the operating characteristics of the device is improved substantially against bias-supply variations.     

Photoinduced Electron Transfer Between Pyridine Coated Cadmium Selenide Quantum Dots and Single Sheet Graphene

Interest in graphene as a two‐dimensional quantum‐well material for energy applications and nanoelectronics has increased exponentially in the last few years. The recent advances in large‐area single‐sheet fabrication of pristine graphene have opened unexplored avenues for expanding from nano‐ to meso‐scale applications. The relatively low level of absorptivity and the short lifetimes of excitons of single‐sheet graphene suggest that it needs to be coupled with light sensitizers in order to explore its feasibility for photonic applications, such as solar‐energy conversion. Red‐emitting CdSe quantum dots are employed for photosensitizing single‐sheet graphene with areas of several square centimeters. Pyridine coating of the quantum dots not only enhances their adhesion to the graphene surface, but also provides good electronic coupling between the CdSe and the two‐dimensional carbon allotrope. Illumination of the quantum dots led to injection of n‐carrier in the graphene phase. Time‐resolved spectroscopy reveals three modes of photoinduced electron transfer between the quantum dots and the graphene occurring in the femtosecond and picosecond time‐domains. Transient absorption spectra provide evidence for photoinduced hole‐shift from the CdSe to the pyridine ligands, thereby polarizing the surface of the quantum dots. That is, photoinduced electrical polarization, which favors the simultaneous electron transfer from the CdSe to the graphene phase. These mechanistic insights into the photoinduced interfacial charge transfer have a promising potential to serve as guidelines for the design and development of composites of graphene and inorganic nanomaterials for solar‐energy conversion applications.     

Nasal secretion analysis in allergic rhinitis, cystic fibrosis, and nonallergic fibromyalgia/chronic fatigue syndrome subjects

Vascular surgery can be safely performed in approximately 60% of patients with advanced peripheral vascular disease, because of the high frequency of concomitant coronary artery disease and consequent increased risk of perioperative cardiac complications. The aim of this study was to validate the hypothesis that endovascular revascularization could be safely applied to high-cardiac-risk patients with a lower incidence of perioperative cardiac complications. One hundred and fourteen patients with peripheral vascular disease referred for revascularization underwent preoperatively a clinical and echocardiographic evaluation, at rest and under dipyridamole stress test, to assess the cardiac risk. Patients with high clinical score (according to Goldman and Detsky), or low left ventricular ejection fraction at rest, or positive dipyridamole stress test, were considered at high cardiac risk. To record adverse cardiac events, all patients were monitored during surgery, postoperatively, and followed up for 18 months after hospital discharge. Forty-eight patients (42%) were found to be at high cardiac risk. In this high-cardiac-risk group, endovascular surgery was performed in 37/48 patients (77%) (group A), while the remaining 11/48 patients (23%) were bypassed with open surgery (group B). Postoperative cardiac complications occurred in 16% of patients in group A and in 45% of patients in group B with two deaths (p < 0.05). At follow-up, 51% of patients in group A and 44% of patients in group B had suffered late cardiac events (p=ns), with 10 deaths in group A and three deaths in group B (p=ns). Limb salvage rate was similar in the two groups (95% group A, 100% group B; p=ns). These data show that high-cardiac-risk patients with limb-threatening ischemia have significantly less perioperative cardiac complications when treated by endovascular procedures instead of bypass surgery. Follow-up data on cardiac events confirm the severity of concomitant coronary artery disease in patients with peripheral vascular disease.     

Repeated oral dose toxicity of iron oxide nanoparticles: biochemical and histopathological alterations in different tissues of rats

Iron oxide (Fe2O3) nanoparticles are widely used in different fields of nanotechnology. However, studies on its toxicological effects in humans and the environment are scarce. Therefore in this investigation 28 days repeated dose oral toxicity studies were conducted on Fe2O3-30 nanoparticles and its counterpart Fe2O3-Bulk with special reference to target biochemical enzymes and histopathological changes in different tissues of female albino Wistar rats. The alterations observed after Fe2O3-30 treatment in various tissues of exposed rats were dose dependent. Low dose was less effective than medium and high doses with low dose demonstrating "no observed adverse effect" (NOAEL). Further, high dose treated rats showed toxic sign and symptoms but no mortality. Due to the repeated doses of Fe2O3-30 nanoparticles, significant inhibition was observed in total, Na(+)-K+, Mg2+ and Ca(2+)-ATPases in brain of exposed rats. Similarly, significant inhibition was recorded in RBC and brain acetylcholinesterase indicating that both synaptic transmission and nerve conduction were affected by this compound. Fe2O3-30 significantly increased aspartate amino transferase, alanine amino transferase and lactate dehydrogenase in serum and liver, whereas, these enzymes were significantly decreased in kidney indicating tissue necrosis and possible leakage of these enzymes into the blood stream. Increased levels of these enzymes in liver as well as in serum might be an adaptive mechanism due to the stress of iron nanoparticles. High dose treated rats of Fe2O3-30 showed dilated central vein, perivascular round cell collections in liver along with focal areas of necrosis, whereas kidney showed focal tubular damage and red pulp congestion, whereas prominent white pulp indices were observed in spleen. However, histopathological analysis of heart and brain tissues failed to show any adverse changes in their architecture exposed to repeated doses of Fe2O3-30 when compared with controls. Fe2O3-Bulk did not induce any adverse effects in either biochemical parameters or histopathology in the treated rats and the changes observed were near to controls and mostly insignificant, indicating that the counter part of nanoparticles i.e., bulk material is less potent than the nanoparticles in causing toxicity in the exposed animals. These results suggested that as particle size decreases, this iron nanoparticle showed increased toxicity, even though the same material is relatively inert in bulk form. The changes observed in these target enzyme activities could be useful as biomarkers of exposure to nanoparticles.