Exopolysaccharide from Pantoea sp. BCCS 001 GH isolated from nectarine fruit: production in submerged culture and preliminary physicochemical characterizations

Food Science and Biotechnology - Exopolysaccharide (EPS), as potential microbial base polysaccharide source, has plenty of applications due to its unique physicochemical structure. A Pantoea sp....     

Cadmium sulfide thin films growth by chemical bath deposition

Cadmium sulfide (CdS) thin films have been prepared by a simple technique such as chemical bath deposition (CBD).A set of samples CdS were deposited on glass substrates by varying the bath temperature from 55 to 75 ℃ at fixed deposition time (25 min) in order to investigate the effect of deposition temperature on CdS films physical properties.The determination of growth activation energy suggests that at low temperature CdS film growth is governed by the release of Cd2+ ions in the solution.The structural characterization indicated that the CdS films structure is cubic or hexagonal with preferential orientation along the direction (111) or (002),respectively.The optical characterization indicated that the films have a fairly high transparency,which varies between 55％ and 80％ in the visible range of the optical spectrum,the refractive index varies from 1.85 to 2.5 and the optical gap value of which can reach 2.2 eV.It can be suggested that these properties make these films perfectly suitable for their use as window film in thin films based solar cells.     

Task scheduling mechanisms in cloud computing: A systematic review

Today, cloud computing has developed as one of the important emergent technologies in communication and Internet. It offers on demand, pay per use access to infrastructure, platforms, and applications. Due to the increase in its popularity, the huge number of requests need to be handled in an efficient manner. Task scheduling as one of the challenges in the cloud computing supports the requests for assigning a particular resource so as to perform effectively. In the resource management, task scheduling is performed where there is the dependency between tasks. Many approaches and case studies have been developed for the scheduling of these tasks. Up to now, a systematic literature review (SLR) has not been presented to discover and evaluate the task scheduling approaches in the cloud computing environment. To overcome, this paper presents an SLR‐based analysis on the task scheduling approaches that classify into (a) single cloud environments that evaluate cost‐aware, energy‐aware, multi‐objective, and QoS‐aware approaches in task scheduling; (b) multicloud environment that evaluates cost‐aware, multi‐objective, and QoS‐aware task scheduling; and (c) mobile cloud environment that is energy‐aware and QoS‐aware task scheduling. The analytical discussions are provided to show the advantages and limitations of the existing approaches.     

Durability of concrete with addition of dry sludge from waste water treatment plants

This paper evaluates the use of dry sludge as an additive for concrete, for which it must be guaranteed that the resulting concrete has the appropriate mechanical strength and durability.In earlier work on the subject, it was shown that the addition of sludge reduces the mechanical strength of concrete. With the addition of 10% sludge in proportion to the amount of concrete, the mechanical strength decreases significantly, making it unsuitable for medium- to high-strength reinforced concrete.One possible area of application would be in the preparation of low-strength mass concrete that could be used for bases and subbases of roads with light traffic, as filler, etc.We subjected the concrete specimens to different types of accelerated attack in order to evaluate long-term performance and compare them with the reference concrete (not containing sludge).The following tests were made:

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Combined wet-dry cycles using fresh water, seawater and water containing 5% sulphates

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Accelerated ageing in an autoclave

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Accelerated carbonation

The performance of the concrete containing sludge was acceptable and comparable to the results obtained for the reference concrete not containing sludge.     

Decoupling between Enthalpy Relaxation and Viscous Flow and Its Structural Origin in Fragile Oxide Glass-Forming Liquids

The structural relaxation kinetics at the glass transition in tellurium oxide (TeO₂)-based glasses has been examined from viscosity and heat-capacity measurements to clarify the features of the structural relaxation in fragile oxide glass-forming liquids. A large decoupling between enthalpy relaxation and viscous flow, i.e., a large discrepancy between the activation energies for the enthalpy relaxation (recovery), Δ H , and viscous flow, E _η, has been demonstrated in TeO₂-based glasses. The values in x K₂O· x MgO·(100 − 2 x )TeO₂ glasses, for example, are ∼919–1051 kJ/mol for Δ H and ∼ 577–701 kJ/mol for E _η, given the ratio of Δ H/E _η≈ 1.44–1.59. Some viscosity and heat-capacity data (all data have been reported previously) obtained from similar experiments in Sb₂O₃–B₂O₃ glasses belonging to the category of strong glass-forming liquids have been reanalyzed in this paper for comparison; a strong coupling was found to exist between Δ H and E _η, i.e., Δ H/E _η≈ 0.98–1.18. An origin of decoupling between Δ H and E _η in fragile glass-forming systems such as TeO₂-based glasses has been discussed by considering the glass structure model for fragile glasses; strongly bonded correlated (highly constrained) regions are surrounded or connected by weakly bonded noncorrelated (unconstrained) parts.     

Urban data and urban design: A data mining approach to architecture education

The configuration of urban projects using Information and Communication Technologies is an essential aspect in the education of future architects. Students must know the technologies that will facilitate their academic and professional development, as well as anticipating the needs of the citizens and the requirements of their designs. In this paper, a data mining approach was used to outline the strategic requirements for an urban design project in an architecture course using a Project-Based Learning strategy. Informal data related to an award-winning public space (Gillett Square in London, UK) was retrieved from two social networks (Flickr and Twitter), and from its official website. The analysis focused on semantic, temporal and spatial patterns, aspects generally overlooked in traditional approaches. Text-mining techniques were used to relate semantic and temporal data, focusing on seasonal and weekly (work-leisure) cycles, and the geographic patterns were extracted both from geotagged pictures and by geocoding user locations. The results showed that it is possible to obtain and extract valuable data and information in order to determine the different uses and architectural requirements of an urban space, but such data and information can be challenging to retrieve, structure, analyze and visualize. The main goal of the paper is to outline a strategy and present a visualization of the results, in a way designed to be attractive and informative for both students and professionals – even without a technical background – so the conducted analysis may be reproducible in other urban data contexts.     

Photocurable shape-memory polyether-polythioether/graphene nanocomposites and the study of their thermal conductivity

Herein a method is described to prepare photocurable thermally-conductive shape memory epoxy/ graphene composites. By photopolymerizing the epoxy resin diglycidyl ether of bisphenol A with an allyl-functionalized ditertiary amine as the curing agent, jointly with a multifunctional thiol, a crosslinked polyether-polythioether co-network was obtained. The presence of a soft domain like the flexible polythioethers enable the co-network to display shape memory properties. By varying the polyether to polythioether ratio it was possible to modulate the shape memory characteristics of the composite. The effect of the concentration of graphene nanoplatelets (GNP) in the composite was also investigated. Shape memory performances revealed excellent values of shape recovery and shape fixity with maximums of 98 and 99% respectively. The temporary- shaped composites with higher concentration of polythioethers and GNP regained their permanent shapes in 2–3 s when heated above the programming temperature. The thermal conductivity in the composites reached 0.39 W/m°K for the composite with 15% w/w of GNP. The presence of the polythioethers in the co-network enhanced the toughness of the composite as revealed by the impact resistance analysis.     

Electrical properties of Cu4ZnSnS2/ZnS heterojunction prepared by ultrasonic spray pyrolysis

Cu₂ZnSnS₄ (CZTS)/ZnS heterojunctions have been prepared by a successive deposition of ZnS and CZTS thin films by ultrasonic spray pyrolysis technique on glass substrates. The cupric chloride concentration has been varied in the starting solution in order to investigate its influence on device properties. CZTS/ZnS heterojunctions were characterized by recording their current-voltage characteristics at different temperatures. The obtained results exhibit a good rectifying behavior of the realized heterojunction. Analysis of these results yields saturation current, series resistance and ideality factor determination. From the activation energy of saturation current we inferred that the thermal emission through the barrier height is the dominant mechanism of the reverse current rather than the defects contribution.     

Prevention of melanin formation by yeast cerebroside in B16 mouse melanoma cells

The effects of plant and yeast cerebrosides on melanin formation were examined in B16 mouse melanoma cells. Addition of yeast cerebroside significantly reduced melanin content to the same level as that of arbutin in control cells, although there was no suppression by plant cerebrosides and bovine brain cerebroside up-regulated melanin formation. None of the bovine brain cerebrosides examined had any effect on tyrosinase activity, but yeast cerebroside reduced the contents of tyrosinase. The results of the present study clearly showed that melanin formation is regulated by several different cerebrosides via tyrosinase. In addition, the findings presented here suggest that cerebrosides containing a 9-methyl type sphingoid base, such as yeast cerebroside, may be useful as skincare products for suppressing melanin formation.     

Dehydration of d-glucose in high temperature water at pressures up to 80 MPa

Reaction of d-glucose in water to yield 5-hydroxymethylfurfural (5-HMF), 1,2,4-benzenetriol (BTO) and furfural was studied at high temperatures (up to 400 °C) and high pressures (up to 80 MPa) using a continuous flow reactor. Maximum temperature and pressure conditions gave maximum furfural yield. Increasing pressure from 40 to 70 and 80 MPa enhanced dehydration reactions to 5-HMF, but also enhanced hydrolysis of 5-HMF leading to the production of BTO and thus lead to lower yields of 5-HMF (below 10%). Remarkably, the dehydration reaction to 5-HMF and the hydrolysis of 5-HMF were both enhanced by the increase in water density at 400 °C.