Nanosponges – a completely new nano-horizon: pharmaceutical applications and recent advances

In recent years, nanosponges (NS) have gained tremendous impetus in drug delivery through nanotechnology. Nanosponges are capable of providing solutions for several formulation related problems. Through this review, scientists working in the field of nanotechnology can have an insight into the techniques of preparation, characterization and applications of NS. Owing to their small size and porous nature they can bind poorly-soluble drugs within their matrix and improve their bioavailability. They can be crafted for targeting drugs to specific sites, prevent drug and protein degradation and prolong drug release in a controlled manner. This review attempts to elaborate different schemes of synthesis of NS and their characterization. Factors affecting drug loading and release have been enumerated. Due to their advantages, NS have not only been explored for their pharmaceutical applications but also have large popularity in allied sciences, especially in water purification.     

Stress–phase-transformation interactions – basic principles,modelling, and calculation of internal stresses

Abstract

The two main effects of stress on phase transformation, kinetics modification and transformation plasticity, are reviewed for both diffusional and non-diffusional transformations. Results for these interactions during the pearlitic and martensitic transformation of steels under uniaxial tensile stress are analysed from a metallurgical point of view. These results are used to produce a model for a triaxial stress state, and in a finite element program for calculating internal stresses during quenching. Transformation plasticity is introduced in the calculation of internal stresses as an additional strain related to the stress state and to the progress of transformation, and the kinetics of martensitic transformation are also related to the stress state. The calculated results show that these phenomena have important consequences on the stress and plastic strain histories during quenching.

MST/9     

Investigations on the extrusion defect – Axial hole or funnel

Axial hole or funnel is a common extrusion defect observed during a direct extrusion process. Though a common defect, the parameters that influence the nature and formation of this defect have not been studied and reported. Further, the die design requirement to avoid the defect has also been not yet established. In this regard, finite element analysis has been carried out to investigate the effect of important extrusion parameters such as extrusion ratio (R), extrusion die angle (θ), deformation zone height (h), friction (μ) and constitutive material behaviour on the defect formation and its characteristic. The conditions under which the defect can be avoided have been established. Physical modeling experiments using plasticine were carried out to validate the numerical modeling results.     

Strategies to synthesise copper oxide nanoparticles and their bio applications – a review

Researchers have identified copper oxide nanoparticles (CuO-NPs) as a key of interest because of their unique shape- and size-dependent bio-medical properties. Researchers have discovered and invented a variety of methods for the synthesis of CuO-NPs under physical, chemical and biological approach. In this review paper, we give an overview of the preparation of CuO-NPs through various methods and also their applications in the bio-medical field. The main aim of this paper is to keep up to date with the myriad ongoing methods of NPs’ synthesis and also examine their applications, especially in the field of medicine.     

Use of sorbitol as pharmaceutical excipient in the present day formulations – issues and challenges for drug absorption and bioavailability

Sorbitol is a popular sugar alcohol which has been used as an excipient in formulations of various drugs. Although from a safety perspective the presence of sorbitol in drug formulations does not raise a concern, reports have emerged and these suggest that sorbitol in drug formulations may alter oral absorption and bioavailability of certain drugs. The focus of this article was to review the published literature of various drugs where pharmacokinetic data has been reported for the drug alone versus drug administered with sorbitol and provide perspectives on the pharmacokinetic findings. Interestingly, for BCS class I drugs such as theophylline, metoprolol, the oral absorption, and bioavailability were generally not affected by sorbitol. However, theophylline oral absorption and bioavailability were decreased when sustained release formulation was used in place of immediate release formulation. For drugs such as risperidone (BCS class II) and lamivudine and ranitidine (BCS class III), the solution formulations showed diminished oral bioavailability in presence of sorbitol, whereas cimetidine and acyclovir (BCS class III), did not show any changes in pharmacokinetic profiles due to sorbitol. Finally, the presence of activated charcoal with sorbitol showed different pharmacokinetic outcome for BCS class I and II drugs.     

In vitro–in vivo extrapolation (IVIVE) for predicting human intestinal absorption and first-pass elimination of drugs: principles and applications

Oral administration remains the preferred dosing method in clinical practice and drug development. Oral bioavailability (F) is a function of the fraction absorbed (F_abs), gastrointestinal or gut wall availability (F_G), and hepatic availability (F_H). Therefore, predicting intestinal absorption (F_abs) and first-pass elimination (F_G and F_H) from in vitro data may facilitate the selection of more orally bioavailable drug candidates in earlier stages of drug discovery and development. This review provides an overview of the determinants of intestinal absorption and first-pass elimination of drugs and focuses on the principles and applications of conventional in vitro--in vivo extrapolation (IVIVE) methods to predict F_abs, F_G, and F_H in humans.     

Thermoplastic–epoxy interactions and their potential applications in joining composite structures – A review

This paper presents a literature survey on the theoretical backgrounds and the past research efforts in relation to the interactions between certain thermoplastics and epoxies, and their applications in polymer blending, epoxy toughening and composite joining. The main objectives are to understand the possible mechanisms of interfacial adhesion between thermoplastic and thermoset polymers, and also to explore the feasible approaches to improve interfacial adhesion for the purposes of joining fibre reinforced polymer (FRP) composite structures by fusion bonding. Further, it is expected that the review would provide some visions to the potential applications of the thermoplastic–thermoset interfacial interactions for the quick assembly of composite structures in cost-effective manufacturing of composite structures, through the uses of the technologies, such as thermoset composite fusion bonding, welding of thermoplastic composites with thermoset composites, and thermoplastic article attachment on thermoset composites.     

Billet quenching extrusion process as efficient and reliable replacement for conventional extrusion of Al–Cu alloys

Abstract

In order to eliminate the separate solution soaking treatment used for Al–Cu extrudates, the influence of billet heat treatments before the extrusion process on a precipitation hardenable AlCu6PbBi (AA2011) alloy was studied. The hot deformation behaviour of the alloy was studied using compression tests. A comparison of the conventional extrusion process, press quenching and billet quenching (BQ) before extrusion was made in production on a 35 MN press. The transformation kinetics was studied by heat treating homogenised samples in salt baths. The mechanical testing, using tensile tests and the Brinell hardness test, and a microstructural investigation, using light and TEM microscopy, revealed that extrusion using the billet quenching process results in the formation of extrudates with similar mechanical properties, hardness and microstructures as those produced using conventional technology. In the extrudates produced by BQ a supersaturated solid solution is formed directly after cooling in a standing water wave, which makes BQ an efficient and reliable substitute for the conventional extrusion process.     

Growth and characterization of Zn1 – x Mg x S thin films for electroluminescent applications

:Mn thin films (x=0–0.30) were prepared by thermal co-evaporation of ZnS, Mg and Mn. The structural investigation shows the solid solution is formed in the Mg composition range x=0–0.25 and phase segregation occurs at higher Mg composition (x > 0.25). The optical band gap shows an increase with increase of Mg composition. The electroluminescent emission corresponding to the transition ion shows a blue shift with increase of Mg composition in the film. :Mn films could be used as an active layer in a.c. thin film electroluminescent (ACTFEL) devices for obtaining green emission color.     

Process and die design for rod extrusion of γ iron

This study is related to materials modeling and die and process design of rod extrusion of γ iron. Strain dependent rate power law is used for materials modeling whose coefficients are arrived at through genetic algorithm (GA). Die profile of the rod extrusion process is optimized to produce products of desirable microstructure at maximum production speed and minimum left out material in the die. The design problem is formulated as a nonlinear programming problem which is solved using GA. Selection of the processing parameters is carried out using dynamic materials modeling (DMM). Using this approach rod extrusion process of γ iron is successfully designed. FE simulation on the optimum profile is also attempted to study deformation behaviour and load requirement.     

A basic need for integration – bringing focus to the scoping process

In response to the lead article in this edition, we have the following observations made mostly on our professional practice. First, good scoping is essential for effective impact assessment (IA) but is rarely done well. Second, interdisciplinary teams are also essential for effective IA and are often used. Third, the use of sustainability as a tool for doing IA is intellectually attractive but may conflict with IA legislation and so should be used only with care.     

Phase change material based cold thermal energy storage: Materials,techniques and applications – A review

This paper gives a comprehensive review on recent developments and the previous research studies on cold thermal energy storage using phase change materials (PCM). Such commercially available PCMs having the potential to be used as material for cold energy storage are categorised and listed with their melting point and latent heat of fusion. Also techniques for improving the thermo-physical properties of PCM such as heat transfer enhancement, encapsulation, inclusion of nanostructures and shape stabilization are reviewed. The effect of stability due to the corrosion of construction materials is also reported. Finally, different applications where the PCM can be employed for cold energy storage such as free cooling of building, air-conditioning, refrigerated trucks and cold packing are discussed.     

Syalon ceramics — their development and engineering applications

This article concentrates on one family of ceramic alloys, the sialons, derived from silicon nitride. The development, chemical composition, mechanical properties and manufacturing routes are described, with current and potential application areas also outlined.     

Electron- and ion-beam-induced maneuvering of nanostructures: phenomenon and applications

Electron-and ion-induced bending (EIB/IIB) phenomena have been studied in self-supported polycrystalline metallic and metal-amorphous bilayered nanocantilevers. The experiments reveal many interesting facts regarding electron/ion-matter interaction, which builds a proper foundation for the understanding of the phenomenon. The mechanism for bending of metallic cantilevers has been proposed to be primarily due to void-induced stress generation during ion beam irradiation. On the other hand, thermal effects have been found to play the dominant role in the case of bending of bilayer (amorphous-metal) nanocantilevers. The instantaneous, reversible, highly controllable and permanent nature of the process has been exploited to fabricate several complicated nanostructures in three dimensions. IIB of the fabricated cantilevers is shown to have a high precession mass sensing aptitude, capable of detecting a change in mass of the order of femtograms.     

Shift and intensity modeling in spectroscopy—general concept and applications

Multivariate analysis and calibration in spectroscopy have been widely used in many fields of applications in recent years. The number of components to use in such applications for sufficiently describing the spectra is dependent on the stability of positions of the peaks of interest. Unwanted shifts give rise to a more complex model, i.e., more components. Various kinds of shift correction can be applied as preprocessing tools to cope with these effects. In this paper we describe a general concept of how to model intensity (peak height) and position as separate phenomena. We described methods and theory from image modeling, and apply them on one-dimensional signals such as traditional Raman spectroscopy.     

Performance evaluation of an active magnetic regenerator for cooling applications – part I: Experimental analysis and thermodynamic performance

In this first part of a two-part paper, a new active magnetic regenerator (AMR) laboratory apparatus is presented and evaluated. The setup is composed of a nested Halbach cylinder magnetic circuit (maximum magnetic flux density of 1.69 T) assembled in phase with a double effect displacer that provides the cold and hot blows to the regenerator. A single packed-bed regenerator with 195.5 g of gadolinium spheres is used in a discontinuous (i.e., reciprocating) cycle. The system performance is evaluated in terms of characteristic curves (i.e., cooling capacity as a function of temperature span), coefficient of performance and second-law efficiency as a function of the utilization factor and operating frequency. Maximum values of COP have been identified for a given temperature span. The maximum values of second-law efficiency were obtained at system temperature spans between 15 and 20 K.     

Performance evaluation of an active magnetic regenerator for cooling applications – part II: Mathematical modeling and thermal losses

In this second part of a two-part paper, a mathematical model of active magnetic regenerators is applied to identify and quantify the main losses taking place in the AMR evaluated experimentally in Part I. Among those losses, the heat interaction with the external environment and the presence of dead (void) volumes between each end of the regenerator and the hot and cold heat exchangers were found to be the main factors that affect the AMR performance. Demagnetizing losses were considered as a function of the matrix geometry, temperature and applied magnetic field. In addition to predicting the time-dependent behavior of the fluid temperature exiting the regenerator during each blow and the cycle average cooling capacity, the model was able to quantify the impact of each loss mechanism on the thermal performance of the AMR.     

Microstructure and mechanical properties of an inertia friction welded INCOLOY alloy 909 – INCONEL alloy 718 joint for rotating applications

Abstract

Inertia welding is a common practice to join axially symmetrical parts for aero-engine applications. The shaft for a new advanced high-pressure compressor will be produced by joining the high strength superalloys INCOLOY® alloy 909 (Incoloy909) and INCONEL® alloy 718 (IN718). IN718 is the work-horse nickel-iron-chromium alloy for a variety of parts for aero-engine applications due to a good combination of relevant mechanical properties, good corrosion resistance and easy fabricability. Incoloy909 is a nickel-iron-cobalt alloy used in aero-engines due to an interesting combination of a nearly constant low coefficient of thermal expansion combined with a constant modulus of elasticity and high strength over a wide range of temperatures. Both alloys are strengthened by precipitationhardening through additions of niobium and titanium. Ring shaped specimens of fully heat-treated Incoloy909 and IN718 are joined by inertia welding. The microstructure in the welded zone is investigated by optical microscopy and transmission electron microscopy with the focus on the Incoloy909 side. Post-weld heat-treatments (PWHT) are evaluated by microstructural investigations and by hardness measurements. The chosen PWHT is characterized by its tensile, creep and load controlled fatigue properties. The results of the mechanical tests are described in terms of the microstructural changes observed in the welded zone.