Search results

To save the economic cost and improve the performance of enterprises, this study aims to synthesize high performance immobilized penicillin G acylase (PGA) carriers with fast reaction speed, high recovery rate of enzyme activity and good reusability through corresponding theoretical guidance and experimental exploration.

A diblock resin was synthesized by reversible addition-fragmentation chain transfer polymerization method using N, N-diethylacrylamide (DEA) and β-hydroxyethyl methacrylate (HEMA) as functional monomers poly(N, N-diethylacrylamide)-b-poly(β-hydroxyethyl methacrylate) (PDEA-b-PHEMA) was obtained, and the effect of the ratio of DEA and HEMA on the activity of PGA was investigated, and the appropriate block ratio of DEA and HEMA was obtained. After that, the competitive rate of HEMA and glycidyl methacrylate (GMA) under the carrier preparation conditions was investigated. Based on the above work, a thermosensitive resin carrier PDEA-b-PHEMA-b-P(HEMA-co-GMA) with different target distances was synthesized, and the chemical structures and molecular weight of copolymers were investigated by hydrogen NMR (¹H NMR).

The lower critical solution temperature of the resin support decreases with the increase of the monomer HEMA in the random copolymerization; the catalytic performance study indicated that the response rate of the immobilized PGA is fast, and the recovery rate of the enzyme activity of the immobilized PGA varies with the distance between the targets. When the molar ratio of HEMA to GMA in the resin block is 8.15:1 [i.e. resin PDEA100-b-PHEMA10-b-P(HEMA65-co-GMA8)], the activity recovery rate of immobilized PGA can reach 50.51%, which was 15.49% higher than that of pure GMA immobilized PGA.

This contribution provides a novel carrier for immobilizing PGA. Under the optimal molar ratio, the enzyme activity recovery could be up to 50.51%, which was 15.49% higher than that of PGA immobilized on the carrier with nonregulated distance between two immobilization sites.

Traditional analytical methods are often time-consuming and require bulky instruments, making their widespread implementation challenging. This paper aims to represent the principal concepts of biosensors as an introduction of this technology to readers and offers a comprehensive understanding of its functions.

The authors provide descriptions of the components, characteristics and advantages of biosensors along with the immobilization methods, followed by a brief discussion.

A biosensor is an analytical device comprising a specific biomolecule and a transducer in conjunction with an output system. The biomolecule recognizes a specific target which leads to a change in physicochemical properties of a system. This biorecognition phenomenon is later converted into a detectable signal by the transducer. Biosensors can essentially serve as rapid and cost-effective devices with excellent sensitivity and specificity for critical purposes in innumerable fields, ranging from scientific research to day-to-day applications.

Here, the authors explain and discuss the approaches and challenges with the aim of leading to an interest in biosensor development and improving their applications.

Using a reversible addition fragmentation chain transfer reaction, a series of resins were prepared by using N, N-diethyl acrylamide (DEA), poly (ß-hydroxyethyl methacrylate) (PHEMA) as hydrophilic blocks and poly (glycidyl methacrylate) (PGMA) as hydrophobic blocks (and as a target for immobilizing penicillin G acylase [PGA]) and the low critical solution temperature (LCST) of which could be adjusted by changing the segment length of blocks.

To make the catalytic conversion temperature of immobilized PGA fallen into the temperature range of the sol state of thermosensitive block resin, a type of thermosensitive block resin, i.e. PDEA-b-PHEMA-b-PGMA (DHGs) was synthesized to immobilize PGA, and the effect of segment order of block resin was investigated on the performance of PGA.

Carrier prepared with monomers molar ratio of n(DEA) : n(HEMA): n(GMA) = 100: 49: 36 presented loading capacity (L) and enzyme activity recovery ratio (Ar) of 110 mg/g and 90%, respectively, and a block resin with LCST value of 33 °C was essential for keeping higher Ar of PGA.

PGA has become an important biocatalyst in modern chemistry industry. However, disadvantages include difficulty in separation, poor repeatability and high cost, which limits the scope of PGA applications. The effective method is to immobilize the enzyme to the carrier, which could overcome the disadvantage of free enzyme.

Olfaction plays a very important role in daily life. The olfactory system has the ability to recognize, discriminate and identify thousands of odorant compounds with extremely high sensitivity and specificity. The research on olfactory system has very important values in exploring the mechanisms of information processing in the other sensory nervous systems and brain. Recently, with the development of molecular biological and microelectronics technology research, the study of olfactory cell-based sensors has made great progress. The purpose of this paper is to provide details of recent developments in olfactory cell-based sensors.

Following an introduction, this paper first discusses some olfactory cell-based biosensors, which focus on the light-addressable potentiometric sensors and the microelectrode arrays. Second, surface modification, microfabrication and microfluidic technology which can improve the efficiency of cell immobilization will be summarized. The research trends of olfactory cell-based sensor in future will be proposed.

This paper shows that the biosensors’ performance is expected to be greatly improved due to the fast development of nanotechnology, optical technology and microelectronics. More and more emerging intelligent olfactory sensors will have a promising prospect in many application fields, including food quality and safety assessment, environmental monitor and human diseases detection.

This paper provides a detailed and timely review of the rapidly growing research in the olfactory cell-based sensors.

The national accounts make no attempt to take earnings from culture, as such, into account. This does not mean that the sums which people pay to go to concerts, visit monuments and museums and for other cultural phenomena are incalculable, for indeed the can be estimated in the same way as the spending of tourists. But to carry out a straight‐forward business audit of the investment in each cultural attraction, the revenues, return on the investment and so on would be to miss the point, or at least much of it. For much of the benefit from such activities comes from “knock‐on effects” such as VAT, the advantages of which spread well beyond the individual sites, and the local authorities responsible for the original investments. Studies in the tourism industry have shown that investments in touristic and cultural attractions have a “multiplier effect” on total spending by visitors. This article looks at a cultural project which sonsists of a network of attractions. It describes a method which makes it possible to assess the economic significance of such networks.

This paper aims to address the questions of different outsourcing strategies between Airbus and Boeing and point out the theoretical limits of the resource-based view (RBV) approach that must be broadened with a finance perspective. Owing to the complexity of systems, the aircraft industry is nowadays structured around a well-organised value chain of product development and manufacturing. However, according to the RBV, capabilities attached to some systems and components are strategic resources and must be kept in house to maintain competitive advantage. In commercial aircraft avionics, critical systems such as flight controls fall directly under this rule, due to substantial risks of passenger safety they deal with.

This study is based on two comparative studies concerning the A330/340 and A350 programmes at Airbus and their equivalents at Boeing, the B777 and the B787. The data are both primary (financial and patent data) and secondary (semi-structured interviews and documentation.

The main result highlights the limits of the RBV model to understand why Airbus has chosen to re-internalise the development and production of flight control systems contrary to Boeing. For both, cost reduction is the main objective of outsourcing, but European firms are more careful with critical resources. The financialisation of aircraft manufacturers’ strategies is another explanatory factor relevant to understand why Boeing outsources strategic resources such as flight controls.

The authors demonstrate the potential of multiplication of research methods to address a question. Second, they try to bring together different theories in a preliminary effort, which gives them some promising stuffy perspective for future works.

By addressing both the RBV and the financialisation perspectives, the authors provide an interesting view of the COmplex Products and Systems (CoPS) challenges.

The findings of this research must provide key of interpretation for business managers, which may consider the two faces, knowledge management and financial, to explain corporate performance.

Several originalities are relevant in this work. From a methodological point of view, the authors offer a comparison between the two main players of commercial aircraft manufacturing, an oligopolistic industry. Second, the data they choose to rely on are both qualitative and quantitative to strengthen the results. Third, at a micro level, this study is original in its approach of linking outsourcing to financialisation.

In this work, the sensing and actuating elements are designed with interdigitated capacitors away from the sensitive element on which the droplet is placed. This pattern helps to prevent interference of electrical elements with the droplet. Choosing shear resonance mode at this proposed structure minimizes the damping effect of droplet touch by the resonator structure. The glass-based standard fabrication method of the proposed biosensor is presented exactly.

Mechanical resonator sensors are extremely limited because of the high damping factor and the high electrical conductivity in the aqueous environment. In this work, a molecule detector biosensor is proposed for droplet analysis, which is possible to fabricate using micro-electro-mechanical systems (MEMS) technology. By electromechanical coupling of resonators as a mechanical resonator structure, a standing mechanical wave is formed at this structure by electrostatic actuating elements.

In this paper, a mechanical resonator structure as a biosensor is proposed for micro-droplet analysis that can be fabricated by MEMS technology. It is designed at a lower cost fabrication method using electrostatic technology and interdigitated capacitors. The response of the biosensor displacement frequency at the resonance frequency of the desired mode is reasonable for measuring the capacitive changes of its output. The mass sensitivity of the proposed biosensor is in the range of 1 ng, and it has a large sensitive area for capturing target molecules.

To evaluate the quality of the proposed design, the stimulated analysis is conducted by COMSOL and results are presented.

This paper aims to present a novel and cost-effective optical biosensor design by simple preparation method for detection of “parathion-methyl,” which is a model pesticide pose to public health and the environment.

The optical enzyme biosensor (TCA) for detection of pesticide “parathion-methyl” was developed on the basis of immobilization of tyrosinase enzyme on chitosan film by adsorption technique. The analytic performance of TCA was investigated by measuring its activity with Ultraviolet (UV) visible spectrophotometer.

Uniform porous network structure and protonated groups of chitosan film provided a microenvironment for tyrosinase immobilization evident from Fourier transform infrared (FTIR) spectroscopy and Atomic Force Microscopy analysis. TCA has a wide linear detection range (0-1.03 µM) with high correlation coefficient and it can detect the parathion-methyl concentration as low as 159 nM by noncompetitive inhibition kinetics. Using the TCA sensor both for ten times and at least 45 days without a significant loss in its activity are the indicators of its good operational and storage stability. Moreover, TCA can be applicable to tap water, providing a promising tool for pesticides detection.

This is the first time to use the in situ analytical technique that can improve the performance of optical enzyme sensor provided to control the pesticide residue better with respect to traditional techniques. The effect of organic solvents on the performance of optical enzyme biosensor was investigated. Inhibition kinetic of the solvents rarely encountered in literature was also studied besides the pH and temperature tolerance of the optical biosensor.

This review aims to focus on recent reported research work on the construction and function of different electrochemical DNA biosensors. It also describes different sensing materials, chemistries of immobilization probes, conditions of hybridization and principles of transducing and amplification strategies.

The human disease-related mutated genes or DNA sequence detection at low cost can be verified by the electrochemical-based biosensor. A range of different chemistries is used by the DNA-based electrochemical biosensors, out of which the interactions of nanoscale material with recognition layer and a solid electrode surface are most interesting. A diversity of advancements has been made in the field of electrochemical detection.

Some important aspects are also highlighted in this review, which can contribute in the creation of successful biosensing devices in the future.

This paper provides an updated review of construction and sensing technologies in the field of biosensing.

Brussels Capital Region has to deal with urban conflicts arising from the different kinds of land uses. On the one hand the process of metropolisation has intensified the inner city's land use through residential, economic and urban development and on the other hand this same process has contributed to the expansion and sprawling of the city beyond its administrative borders. The city's main challenge is to ensure the cohabitation of different urban forms and densities in a multi-scale level related to metropolitan and local functions (Ananian P. 2010). Brussels, originally an industrial city, has become an administrative centre, generating a series of disaffected areas. Urban regeneration and sustainable development policies aim to improve the standard of living through urban, social and economic enhancements. Indeed, these policies deal with the construction, renovation and requalification of obsolete areas into new dwelling complexes. In this context, the present article shows the results of a broader research commissioned by the Brussels Capital Region on residential densification between 1989 and 2007(Declève B. Ananian P. et al 2009). Through the analysis of this inventory, we have identified three main techniques concerning the requalification of old places into residential uses: firstly the reurbanisation of brownfields generated by the delocalisation of large facilities; secondly the requalification and reconversion of isolated buildings (abandoned and obsolete industrial and office buildings) and last but not least, the recycling of terrains merged into the urban fabric of old neighbourhoods. Following two methodological approaches (morphological observation and analysis of social perception), this research has shown us that, in the last twenty years of housing production in Brussels, the main abandoned buildings and sites that were available were requalified, increasing density and improving urbanity through the diversity of the urban forms adopted for the public and private spaces.