Use of ridge regression for improved estimation of kinetic constants from PET data

The estimation of parameters in radio-tracer models from positron emission tomography (PET) data by nonlinear least squares (NLS) often leads to results with unacceptable mean square error (ME) characteristics. The introduction of constraints on parameters has the potential to address this problem. We examine a ridge-regression technique that augments the standard NLS criterion by the addition of a term which penalizes estimates which deviate from physiologically reasonable values. A variation on a plug-in methodology of Hoerl et al. [7] is examined for data-dependent selection of the degree of reliance to place on the penalizing term. A simulation study is carried out to evaluate the performance of this approach in the context of estimation of kinetic constants in the three-compartment model used to analyze data from PET studies with fluoro-deoxyglucose (FDG). Results show that over a range of realistic noise levels, the ridge-regression procedure can be expected to reduce the root ME of parameter estimates by 60%. This result is not found to be substantially dependent on the precise formulation of the penalty function used. Thus, the use of ridge regression for estimation of kinetic parameters in PET studies is considered to be a promising tool.     

Addressing space‐constraint driven selfishness in smart opportunistic environment

A smart opportunistic environment is a physical space, which allows the smart physical objects to communicate in the presence of disruption in connectivity. Because, the objects in such an environment are buffer constrained, some of the objects will not participate in data forwarding, when there is scarcity of storage (buffer) space. In this paper, we focus on such selfish behavior of objects triggered by space constraints in a smart opportunistic environment. We propose a novel data forwarding algorithm, selfishness and buffer‐aware routing (SBR), in which a node is chosen as a relay, based on its capability, which is a function of its available buffer space and past encounter history (delivery predictability) with the destination. SBR can efficiently utilize the limited buffer space in a node with a buffer management scheme, WSD. It can also detect space constraint driven selfish behavior of nodes and resolve it using a reputation‐based technique, MSD. We have conducted simulation using both synthetic and real‐world traces for evaluating our proposed SBR algorithm. For analyzing the performance of the algorithm in real‐time, a smart vehicular test‐bed is developed. Simulation results and test‐bed implementation show that our algorithm performs better in terms of higher delivery ratio, lower overhead ratio, and lower delivery delay, compared with existing opportunistic data forwarding algorithms.     

Graphene oxide nanoflakes from various agrowastes

Nowadays, the synthesis of graphene/ graphene oxide from graphite precursor using oxidizing agents is the most common procedure, but the direct synthesis of graphene or graphene oxide from a non-graphitic carbonaceous material without using inert atmosphere is really a great challenge. Besides, the chemistry behind the development of graphitic structure from a non-graphitic material during the thermal heating is still not clearly understood. In this research work, three agrowaste materials viz. rice husk, sugarcane bagasse and newspaper were selected and subjected to pyrolysis in presence of trace amount of air. The continued heating at the optimum temperature has resulted in aromatization and condensation along with the oxidation within the cellulosic structure of the agrowaste, which finally resulted in the formation of graphene oxide nanoflakes directly. The mechanism of formation of graphene oxide from these agrowaste materials was studied, which suggested that any carbonaceous waste materials can be converted to graphene oxide by optimizing the thermal heating conditions.     

Functional properties of sonicated and non-sonicated extracted leaf protein concentrate from Diplazium esculentum

Leaf protein concentrate of edible fern Diplazium esculentum was extracted using sonication and non-sonication methods and its functional properties were evaluated. The leaf protein concentrate contained 34.28 and 9.89% protein for sonicated and non-sonicated extractions, respectively. Sonication yielded (36.36%) better emulsion activity over non-sonication (31.10%). Foaming capacity was also found better in sonication (7.27%) over non-sonication (6.99%), and oil absorption capacity also improved in sonication (7.55 g of oil/g) over its counterpart (7.41 g of oil/g). Contact angle experiments with the leaf protein concentrate evidenced the enhancement of more hydrophilicity of the sonicated sample. Thermal properties of the leaf protein concentrate with sonication evidenced more stability (55.58 and 95.95°C) over the non-sonicated (46.75 and 75.60°C). Fourier transform infrared spectral analysis with the leaf protein concentrate of Diplazium esculentum was used to assess the secondary structural data such as α-helix and β-sheets. The various percentages of secondary structures of protein in sonicated and non-sonicated samples were 49.06 and 69.16% for α-helix, 33.59% and 17.02% for β-sheet and 42.02 and 35.68% for turn, respectively. The results of the present investigation showed credible evidence to support that sonication method of extraction of leaf protein concentrate was better in terms of protein yield and functional properties as compared to the non-sonication. The sonicated extracted leaf protein concentrate has the potential for developing value added products.     

Biodegradation of Chemically Modified Jute Fibers

Degradation of lignocellulosic fibers such as untreated jute fibers and those treated with an alkaline solution of neem oil and phenolic resin are studied by monitoring enzyme activities during burial of fibers within a compost of organic soil and animal refuse. Results indicate that biodegradation of fibers is dominated initially by enzymatic hydrolysis of hemicellulose and amorphous cellulose and subsequently by crystalline cellulose degradation. For neem oil and phenolic resin treated fibers, the degradation of hemicelluloses and cellulose were found to proceed at a remarkably slower rate compared to untreated fibers due to relative nonavailability of degradable matter.     

Managing the Topological Expansion of Computer Networks in an Optimal Way

This article describes a subgradient-based near-optimal heuristic algorithm designed for minimizing the search of links that need to be added to an existing telecommunications network to enhance the survivability and routability of the network.     

Swelling and rheological study of calcium phosphate filled bacterial cellulose-based hydrogel scaffold

This work focuses mainly about swelling and rheological properties of calcium phosphate filled bacterial cellulose (BC)-based hydrogel scaffolds. Calcium phosphate is incorporated in the form of hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) in different ratios, that is, 00:00, 10:90, 20:80, 40:60, 50:50, and 60:40. These scaffolds are also comprised with polyvinylpyrrolidone (PVP), poly(ethylene glycol), agar, and glycerin; designated as “BC-PVP” and “BC-PVP-β-TCP/HA.” All the hydrogel scaffolds are showing the notable viscoelastic property at 28 and 37 °C temperatures. The degree of swelling is found significant in BC-PVP-β-TCP/HA_50:50 scaffold and it is notably elastic at 37 °C after 5 min of swelling. However, after 60 min of swelling and at equilibrium swelling state, the elastic property of BC-PVP-β-TCP/HA_20:80 is revealed the highest. Considering the degree of swelling and rheological properties, the BC-PVP-β-TCP/HA_50:50 and BC-PVP-β-TCP/HA_20:80 hydrogel scaffolds found suitable for their application in bone tissue engineering or bone tissue regeneration. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48522.     

Impact behavior of unidirectional polyethylene–glass fibers: PMMA hybrid composite laminates

Unidirectional (UD) hybrid laminates based on glass fibers (GF) and high performance polyethylene fibers (PEF) were prepared with partially polymerized methyl methacrylate (MMA) at room temperature followed by heating at 55°C (well below the softening point of PEF) for 2 h. Izod impact strength of the composites was then measured. An interesting observation of the study was the change in impact strength that was largely dependent on the position of GF and PEF ply/plies present within the hybrid laminates. When the ply/plies of PEF were at the impacted surface, the impact strength showed a higher value than that of the case when GF ply/plies were at the impacted surface of the hybrid laminates. © 1996 John Wiley & Sons, Inc.