Optimization of a microfluidic mixer for studying protein folding kinetics

We have applied an optimization method in conjunction with numerical simulations to minimize the mixing time of a microfluidic mixer developed for protein folding studies. The optimization method uses a semideterministic algorithm to find the global minimum of the mixing time by varying the mixer geometry and flow conditions. We describe the minimization problem and constraints and give a brief overview of the optimization algorithm. We present results of the optimization, including the optimized geometry and parameter sensitivities, and we demonstrate the improvement in mixing performance with experiments using microfabricated mixers. The dye-quenching experiments of the original and optimized mixer designs show respective mixing times of 7 and 4 mus, a 40% reduction. The new design also provides more uniform mixing across streamlines that enter the mixer. The optimized mixer is the fastest reported continuous flow mixer for protein folding.     

Synthesis and characterization of diopside glass–ceramic matrix composite reinforced with aluminum titanate

Glass–ceramic composites in the SiO₂–CaO–MgO–(Na₂O) system, reinforced with 5, 10 and 20 wt.% aluminum titanate were synthesized by pressureless sintering. Optimum sintering temperatures with maximum relative density were determined for each composition. The composites were fired above the crystallization peak temperature of glass–ceramic. Mechanical properties of glass–ceramic and sintered composites, such as fracture toughness, flexural strength and Vickers microhardness, were investigated. The sintered composites were characterized by scanning electron microscopy (SEM), energy dispersion spectroscopy (EDS) and X-ray diffraction (XRD). The results showed that the composite containing 10 wt.% aluminum titanate has desirable behavior in comparison to the base glass–ceramic and the other compositions. It seems that crack deflection by aluminum titanate particles is the prevalent mechanism for improving mechanical characteristics.     

Effect of Na diffusion on the formation of fibrous microcrystals of manganese oxide

Diffusion of sodium through MnO₂ lattice in a high-temperature solid-state reaction can affect the original structure of manganese oxide. This effect is significantly concentration-dependent. For x < 0.5 in Na_xMnO₂, the chemical structure of sodium manganese oxide is accompanied by the formation of manganese oxide nanowires. The amount of such nanowires increases by increasing the concentration. For x > 0.5, it tends to form conventional layered structure (with microscale particles). In the case of MnO₂, this phenomenon is only for Na diffusion, when a chemical structure corresponding to Na_0.44MnO₂ (JCPDS: 27-0750) is formed.     

Biowaste-Derived,Self-Organized Arrays of High-Performance 2D Carbon Emitters for Organic Light-Emitting Diodes

Low-cost flexible organic light-emitting diodes (OLEDs) with nanoemitter material from waste open up new opportunities for sustainable technology. The common emitter materials generated from waste are carbon dots (CDs). However, these have poor luminescent properties. Further solid-state emission quenching makes application in display devices challenging. Here, flexible and rigid OLED devices are demonstrated using self-assembled 2D arrays of CDs derived from waste material, viz., human hair. High-performance CDs with a quantum yield (QY) of 87%, self-assembled into 2D arrays, are achieved by improving the crystallinity and decreasing the CDs' size distribution. The CD island array exhibits ultrahigh hole mobility (≈10⁻¹ cm² V⁻¹ s⁻¹) and significant reduction in solid-state emission quenching compared to pristine CDs; hence, it is used here as an emitting layer in both indium tin oxide (ITO)-coated glass and ITO-coated flexible poly(ethylene terephthalate) (PET) substrate OLED devices, without any hole-injection layer. The flexible OLED device exhibits a stable, voltage-independent blue/cyan emission with a record maximum luminescence of 350 cd m⁻², whereas the OLED device based on the rigid glass substrate shows a maximum luminescence of 700 cd m⁻². This work sets up a platform to develop next-generation OLED displays using CD emitters derived from the biowaste material.     

Inverse identification of time-harmonic loads acting on thin plates using approximated Green’s functions

In this paper, a non-iterative technique is proposed for the transverse load identification on Kirchhoff plates using approximate Green’s functions (AGFs). In this way, we firstly employ the recently introduced meshless method to construct the AGFs, as the combination of a series of Trefftz basis, i.e. Exponential basis functions (EBFs), and the fundamental solutions of the governing equation. As will be explained, using a proper set of EBFs, as well as a collocation technique, enables us to construct the AGFs for different types of domain shape and boundary conditions. In the second step, a set of artificially generated results, in the absence of realistic experimental results, are used to express the plate’s response field, i.e. deflection or velocity fields, as a series of AGFs through a collocation technique. It will be shown how the constant coefficients of the response series are related to the intensity of the reconstructed force at a set of selected points. The proposed method is capable of constructing both distributed and concentrated loads with desirable accuracy. This ability is shown in the solution of three sample problems of the static and time-harmonic force recovery.     

On probabilistic n-ary hypergroups

The T-fuzzy n-ary subhypergroups of an n-ary hypergroup are defined by using triangular norms and some related properties are hence obtained. In particular, we consider the probabilistic version of n-ary hypergroups by using random sets and show that the fuzzy n-ary hypergroups defined by triangular norms are consequences of some probabilistic n-ary hypergroups under certain conditions. Some results on n-ary hypergroups recently given by Davvaz and Corsini are extended.     

Combining OWL ontologies using -Connections

The standardization of the Web Ontology Language (OWL) leaves (at least) two crucial issues for Web-based ontologies unsatisfactorily resolved, namely how to represent and reason with multiple distinct, but linked ontologies, and how to enable effective knowledge reuse and sharing on the Semantic Web.In this paper, we present a solution for these fundamental problems based on -Connections. We aim to use -Connections to provide modelers with suitable means for developing Web ontologies in a modular way and to provide an alternative to the owl:imports construct.With such motivation, we present in this paper a syntactic and semantic extension of the Web Ontology language that covers -Connections of OWL-DL ontologies. We show how to use such an extension as an alternative to the owl:imports construct in many modeling situations. We investigate different combinations of the logics , and for which it is possible to design and implement reasoning algorithms, well-suited for optimization.Finally, we provide support for -Connections in both an ontology editor, SWOOP, and an OWL reasoner, Pellet.     

Benchmark Problem for Response Control of Wind-Excited Tall Buildings

This paper presents an overview and problem definition of a benchmark problem for the response control of wind-excited tall buildings. The building considered is a 76-story 306 m concrete office tower proposed for the city of Melbourne, Australia. The building is slender with a height to width ratio of 7.3; hence, it is wind sensitive. Wind tunnel tests for such a 76-story building model have been conducted at the University of Sydney and the results of across-wind data are used in the present benchmark problem. Either active, semiactive, or passive control systems can be installed in the building to reduce the wind response, although only an active control sample problem has been worked out to illustrate the control design. In the case of active control systems, either an active tuned mass damper or an active mass driver can be installed on the top floor. In the case of passive or semiactive systems, such as viscous dampers, viscoelastic dampers, electrorheological, or magnetorheological dampers, etc., control devices can be installed in selected story units. Control constraints and evaluation criteria are presented for the design problem. A simulation program based on the linear quadratic Gaussian technique has been developed and made available for the comparison of the performance of various control strategies.     

Institutionalized computer workaround practices in a Mediterranean country: an examination of two organizations

Information systems research often treats computer workarounds tangentially and as temporary phenomena. This exploratory research embraces anomalous system use in general and computer workarounds in particular by suggesting why the latter can be institutionalized and how they may be manifested in practice. Anomalous use is defined as sociomaterial actions around an IT artifact not consistent with its design or related official rules that nevertheless constitute system enactment in practice. The persistence of computer workarounds might be explained by the tension between top-down pressures from the external environment and bottom-up constraints from day-to-day operational work. These insights are drawn from an up-close study of workarounds in two cases from the Mediterranean region. The workaround practices involve decoupling and loose coupling, effectively creating ‘equilibrium’ between the aforementioned top-down and bottom-up influences. This may be attributed to parity between the influence exercised by external regulatory/accrediting bodies and the constraints of day-to-day work within the focal organization (i.e., work ethos, material constraints, and discretion to decouple). Our results show why some computer workarounds exhibit institutionalized behavior and their antecedent conditions. We also suggest that constituent workaround practices may exist as twin but distinctive behavioral patterns – non-compliance (or partial compliance) with an official rule and partially (or fully) working around designed systems.