Valorization of maize bran to obtain biodegradable plastic films

Cellulose‐enriched residues from maize bran can be transformed into plastic films after esterification of the cellulose by various fatty acid chlorides. Alkali pretreatment and acidic activation of the sample are necessary before the esterification reaction in order to form esters. The degradation by microorganisms of the plastic film was also studied. We showed that the isolated strain (chromobacterium violaceum) can hydrolyze modified cellulose plastic films. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 3040–3045, 1999     

Value-added services in next-generation SONET/SDH networks

Advances in next-generation SONET/SDH have introduced novel features for generic protocol framing/encapsulation, virtual concatenation, inverse multiplexing, dynamic circuit adjustment, and so on. In turn, these provisions have enabled much improved multi-tiered service provisioning and are viewed very favorably by carriers, particularly incumbents. This article looks at this evolved framework with a particular focus on value-added services creation. Results from a sample performance evaluation study also are presented to quantify some of the achievable gains.     

EARP: An Enhanced ACO-Based Routing Protocol for Wireless Sensor Networks with Multiple Mobile Sinks

A plenty of Ant Colony Optimization (ACO)-based routing algorithms have been proposed to find optimal path of mobile sinks in Wireless Sensor Networks (WSNs). However, they concentrate on energy efficiency and ignore fault tolerance for critical data collection points like Cluster Heads (CHs). They supposed an ideal scenario where there are no failures which is not the case in reality due to failures resulting from unattended and hostile deployment environments and so on. Moreover, the existing routing protocols are not application-specific enabled (i.e., the parameters cannot be adapted to the application’s requirements). In this paper, we propose an energetically-optimized multi-sink-based clustered WSN model along with a fault-tolerant and energy-efficient Enhanced ACO based Routing Protocol (EARP) to provide reliable data transmission in case of encountering a faulty path. Unlike existing studies, EARP addresses jointly the different constraints of forest fires detection application like fault tolerance, network lifetime and response time. The proposed EARP is simulated along with its counterparts in a general scenario based on various main metrics and also in an application-specific scenario (forest fires detection) based on network lifetime and response time. The simulations results prove its superiority, compared to its peers, in both scenarios.

     

Layer 1 Virtual Private Networks in Multidomain Next-Generation Networks

High-capacity e-science and consumer applications require transport networks that are dynamically provisioned. Rapid advances in next-generation SONET/SPH and optical switching along with GMPLS control have enabled many new services' provisioning capabilities. In particular, a key paradigm is the new layer 1 virtual private network framework, which allows clients to directly provision their own services without deploying expensive infrastructures. This article presents an overview of L1-VPN and describes a resource management scheme that will enable transport network virtualization across a multidomain network infrastructure. The scheme is implemented in both centralized and distributed control frameworks, and allows for dynamic sharing of transport resources. A case study of performance analysis results is presented showing a distributed control plane in a multidomain network architecture achieving higher VPN carrying capacity than a centralized control plane     

Synthesis and antiviral evaluation of pyrazinones substituted with acyclic chains

The synthesis of a series of pyrazine analogues of the anti-herpes compound, acyclovir is described. These syntheses were accomplished by various methods: in the presence of a Lewis acid or NaH for hydroxyethoxymethyl and hydroxybutyl groups or by sequential oxidation/reduction of 1-(beta-D-ribofuranosyl)-2-pyrazinones for 2',3'-acyclonucleosides. Antiviral (HSV-1, CMV, Cox B4, HIV-1) properties of these compounds were determined.     

Stimulation of AMP‐activated protein kinase and enhancement of basal glucose uptake in muscle cells by quercetin and quercetin glycosides,active principles of the antidiabetic medicinal plant Vaccinium vitis‐idaea

Several medicinal plants that stimulate glucose uptake in skeletal muscle cells were identified from among species used by the Cree of Eeyou Istchee of northern Quebec to treat symptoms of diabetes. This study aimed to elucidate the mechanism of action of one of these products, the berries of Vaccinium vitis idaea, as well as to isolate and identify its active constituents using a classical bioassay‐guided fractionation approach. Western immunoblot analysis in C2C12 muscle cells revealed that the ethanol extract of the berries stimulated the insulin‐independent AMP‐activated protein kinase (AMPK) pathway. The extract mildly inhibited ADP‐stimulated oxygen consumption in isolated mitochondria, an effect consistent with metabolic stress and the ensuing stimulation of AMPK. This mechanism is highly analogous to that of Metformin. Fractionation guided by glucose uptake activity resulted in the isolation of ten compounds. The two most active, quercetin‐3‐O‐glycosides, enhanced glucose uptake by 38–59% (50 μM; 18 h treatment) in the absence of insulin. Quercetin aglycone, a minor constituent, stimulated uptake by 37%. The quercetin glycosides and the aglycone stimulated the AMPK pathway at concentrations of 25–100 μM, but only the aglycone inhibited ATP synthase in isolated mitochondria (by 34 and 79% at 25 and 100 μM, respectively). This discrepancy suggests that the activity of the glycosides may require hydrolysis to the aglycone form. These findings indicate that quercetin and quercetin 3‐O‐glycosides are responsible for the antidiabetic activity of V. vitis crude berry extract mediated by AMPK. These common plant products may thus have potential applications for the prevention and treatment of insulin resistance and other metabolic diseases.     

Acidic activation of cellulose and its esterification by long‐chain fatty acid

Cellulose‐enriched residues from wheat bran can be transformed in bioplastics after esterification of the cellulose by lauroyl chloride. Before the esterification reaction, an activation step with a swelling of the sample in dilute acid and subsequent drying was required. This activation had a marked influence on the amount of esterified product and its degree of substitution. Using pure cellulose as well as cellulose‐enriched agricultural residues, we have shown that the cellulose was totally recovered after this pretreatment and that partial hydrolysis of cellulose chains occurred during the drying step, which probably improved the accessibility to chemical reagents. The possible role of sulfuric acid as catalyst for the esterification reaction of the cellulose by lauroyl chloride was discussed. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 1933–1940, 1999     

Preliminary study of formation of films from cellulose-enriched agricultural by-products

Two agricultural by-products, sugar-beet pulp and wheat bran, have been examined for their suitability to be transformed into bioplastics by esterification by lauroyl chloride. Influence of cellulose content was studied on eleven samples enriched in cellulose after chemical or enzymatic removal of pectins from sugar-beet pulp and heteroxylans from wheat bran. After a pretreatment by immersion in 0.5 mol/L sulfuric acid, esterification was carried out with lauroyl chloride. Neither the amount of cellulose nor the extraction treatment had a marked influence on the formation of plastic. A film could be obtained from all the wheat-bran samples, including samples with low cellulose content, but only from one sugar-beet pulp sample. The crystallinity of the cellulose in sugar-beet pulp and wheat bran were different. The nature of cellulose could be responsible for the failure of sugar-beet pulp residues to form plastic. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68:331–337, 1998     

Remote Laboratories for Optical Circuits

This paper presents a remote laboratory implementation for an optical circuits course. The process from design and implementation towards assessment and continuous improvement phase is outlined. The design of the experiments involved the research on remote access technology and the investigation of best practices for an experimental setup. The first pilot implementations were used to determine the possible shortfalls during an ldquoIntroduction to an Optical Communicationsrdquo course in fall 2004 at the University of Colorado, Boulder, and an ldquoOptical Circuitsrdquo course in fall 2005 at the University of Houston, Houston, TX. After improvements, two experiments were pilot tested during spring 2006 at the University of Houston. Assessment of learning outcomes and teaching methods were performed. The remote access methods, in addition to the delivery of the class and lectures, are presented in the paper. Delivery of a class with remote laboratories and videotaped lectures are also outlined under future directions of this project.     

Buried interface characterization in optoelectronic materials by interference microscopy

Abstract

In optoelectronic materials development, the analysis of buried interfaces is sometimes necessary in order to achieve the best optical and electrical performance. Interference microscopy has been investigated as a means to characterize interfaces buried under transparent layers. This technique is typically used at the air/material surface but since it is a non-contacting optical far field technique, it can also be used to measure buried interfaces which are innaccessible by near field scanning probes. We have succeeded in measuring the nanometric roughness of interfaces of porous silicon layers on silicon and of up to three successive buried interfaces in rare earth doped fluoride glass planar waveguides having reflectivities as low as 10^?4 using phase stepping microscopy. Errors in the measured roughness values were introduced with increased depth of the interface, due to the distortion of the wavefront passing through the overlying transparent layer. Scanning white light interferometry was also used to measure the depth of the different interfaces in cases where the refractive indices were known to be homogeneous. Further work is required to better understand the origin of errors in the measurements due to the presence of the overlying transparent layers in order to improve the accuracy of the technique.