Research Needs and Opportunities in the Dry Conservation of Fruits and Vegetables

The consumer demand for healthy convenience meals with 'near fresh' properties challenges researchers and industry to develop new or improved conservation procedures for food products. However, this recent food trend towards fresh image on one ride and convenience on the other side often conflict. In most cases the fresh quality is negatively affected by the processing procedure. Therefore nowadays efforts ars focussed on extending the shelf life of fresh products. However, sophisticated energy demanding facilities are required for storage and transporation, whereas thc use of ecologically unsound cooling agents is a major drawback.

The development of a dehydration process on the basic of electromagnetic energy (EME) may bring about a major breakthrough with respect to the retention of product quality and improved rehydration characteristics. Due to the tenfold weight reduction established in the dehydration process transport and storage costs are minimised thus reducing energy consumption. In comparison with fresh and frozen products minimal storage facilities are required.

The strategy of a consortium of five EC-research centres and two dutch drying companies is to combine and fine tune hot air drying (low processing costs) and EME-drying (quality retention) into a hybrid process, to compare the performance with conventional methods and to include packaging and storage effects.

Optimisation of the rewettability is one of the major concems since food materials with near fresh properties can only be obtained from dry material if rehydration characteristics ars excellent. To establish such dried fruit and vegetables will be considered as blends of polymeric materials. Many quality deterioration mechanisms can be attributed to the mobility of the polymeric matrix and the diffusion of water. Properties thus depend on the composition, the physical properties of the polymers (mobility) and the overall structure of the dried material.     

Preparation of monolithic catalysts

Monolithic catalysts can be attractive replacements for conventional catalysts in randomly packed beds or slurry reactors. The conventional procedures for preparing catalysts, however, cannot simply be applied to monolithic catalysts. Different procedures are discussed on how to put a coat layer of a catalyst support material like alumina, silica, or carbon on a monolith body by either filling the pores in that support or by putting a layer on that support. Different methods to apply an active phase to the support are discussed as well. Finally, methods to convert ready-made catalysts into monolithic catalysts are presented.     

Gas–liquid mass transfer in rotating solid foam reactors

Three-phase reactor designs based on rotating solid foams for the application in the fine chemical industry are developed. The aim is to use solid foams both as a catalyst support and stirrer in order to mix the gas and liquid phases and create fine gas bubbles. Gas–liquid mass transfer data are presented for different solid foam stirrer configurations and compared to an optimized Rushton stirrer. Solid foam stirrers were developed in a blade and a block design. Both foam reactor designs work at stirring rates below 600 rpm. Using the foam blade design, gas bubbles are mainly created by the turbulence at the gas–liquid interface. Large bubbles are broken up by the foam blades. Using a foam block design, rotation leads to the structurization of the reactor volume into sections strongly differing in gas holdup, flow behavior and bubble size distribution. This results in a gas–liquid mass transfer, which is 50% higher than the Rushton stirrer used as comparison. The foam stirrer designs can be easily used in ordinary three-phase reactors and show a high potential for further optimization of the gas–liquid flow pattern and therefore for further increase of the rate of mass transfer.     

Designing flow and temperature uniformities in parallel microchannels reactor

A design methodology is proposed to maintain gas and liquid flow nonuniformities below an acceptable limit in a parallel micro/millichannels reactor by determining the maximum allowed temperature deviation in each part of the reactor. The effect of temperature deviation on flow distribution was quantified using a hydraulic resistive network model. The effect of flow rate on temperature deviation was demonstrated using a one‐dimensional energy balance model. Experiments were conducted using the barrier‐based micro/millichannels reactor (BMMR). Flow distribution in the BMMR is based on placing hydraulic resistances (barrier channels) in the gas and liquid manifolds to regulate the flows. Temperature deviation in the barrier channels affects flow nonuniformity by 10 times more than in the reaction channels. Above a certain critical liquid residence time, flow rate has no significant effect on the temperature deviation which depends on the liquid used, reactor material of construction, and its geometrical dimensions. © 2014 American Institute of Chemical Engineers AIChE J, 60: 1941–1952, 2014     

改善热轧带钢板形和平直度的先进工艺包

使用先进的工艺模型可以精确计算工作辊弯辊和窜辊等辊缝执行机构所需要的设定,从而在考虑轧机中物料横向流动行为以及热应力对工作辊凸度影响等条件下确保优化辊缝形状。介绍奥钢联开发的改善热轧带钢板形和平直度的新型工艺包和工艺模型。     

Smart Eutectic Gallium–Indium: From Properties to Applications

Eutectic gallium–indium (EGaIn), a liquid metal with a melting point close to or below room temperature, has attracted extensive attention in recent years due to its excellent properties such as fluidity, high conductivity, thermal conductivity, stretchability, self-healing capability, biocompatibility, and recyclability. These features of EGaIn can be adjusted by changing the experimental condition, and various composite materials with extended properties can be further obtained by mixing EGaIn with other materials. In this review, not only the are unique properties of EGaIn introduced, but also the working principles for the EGaIn-based devices are illustrated and the developments of EGaIn-related techniques are summarized. The applications of EGaIn in various fields, such as flexible electronics (sensors, antennas, electronic circuits), molecular electronics (molecular memory, opto-electronic switches, or reconfigurable junctions), energy catalysis (heat management, motors, generators, batteries), biomedical science (drug delivery, tumor therapy, bioimaging and neural interfaces) are reviewed. Finally, a critical discussion of the main challenges for the development of EGaIn-based techniques are discussed, and the potential applications in new fields are prospected.     

Reversible Soft Top‐Contacts to Yield Molecular Junctions with Precise and Reproducible Electrical Characteristics

The reproducibility of the electrical characteristics of molecular junctions has been notoriously low. This paper describes a method to construct tunnel junctions based on self‐assembled monolayers (SAMs) by forming reversible electrical contacts to SAMs using top‐electrodes of a non‐Newtonian liquid‐metal (GaO_x/EGaIn) stabilized in a microfluidic‐based device. A single top‐electrode can be used to form up to 15–25 junctions. This method generates SAM‐based junctions with highly reproducible electrical characteristics in terms of precision (widths of distributions) and replicability (closeness to a reference value). The reason is that this method, unlike other approaches that rely on cross‐bar or nano/micropore configurations, does not require patterning of the bottom‐electrodes and is compatible with ultra‐flat template‐stripped (TS) surfaces. This compatibly with non‐patterned electrodes is important for three reasons. i) No edges of the electrodes are present at which SAMs cannot pack well. ii) Patterning requires photoresist that may contaminate the electrode and complicate SAM formation. iii) TS‐surfaces contain large grains, have low rms values, and can be obtained and used (in ordinary laboratory conditions) within a few seconds to minimize contamination. The junctions have very good electrical stability (2500 current‐voltage cycles and retained currents for 27 h), and can be fabricated with good yields (≈78%).     

Evaluation of isotopic boron (11B) for the fabrication of low activation Mg11B2 superconductor for next generation fusion magnets

In this study, we analyze the properties of boron isotope (¹¹B)-rich powders from three different sources, that is, American, Cambridge, and Pavezyum, to fabricate the bulk Mg¹¹B₂ superconductors and evaluate their superconducting properties. While ¹¹B-rich powder is an essential precursor to fabricate Mg¹¹B₂ superconductors for fusion magnet applications, the properties of the ¹¹B powder turned out to be critical to determine the quality of the final superconducting product. Therefore, appropriate control of processing conditions is needed to comply with the requirements of the nuclear fusion application. Analysis of the B isotope ratio by accelerator mass spectroscopy and neutron transmission revealed that all three types of powder are enriched with ¹¹B to better than 99 at % quality. In addition, Pavezyum's ¹¹B shows the lowest crystallinity and smallest crystalline domain size as evidenced by the high-resolution X-ray diffractometer and scanning electron microscopy. The chemical states of the boron isotope investigated with near edge X-ray absorption fine structure spectroscopy and X-ray photoemission spectroscopy also reveals that Pavezyum boron has amorphous structure. Mg¹¹B₂ bulks and multi-filamentary (12-filament) wires have been manufactured, sintered at different temperatures and characterized via the transport critical current density. The wire with Pavezyum ¹¹B shows three times higher current carrying capacity at a particular magnetic field compared to the wire using Cambridge ¹¹B and hence, Pavezyum ¹¹B boron has the potential for manufacturing fusion grade Mg¹¹B₂ based magnets. The results of this study demonstrated that Boron powders with higher purity, smaller grain size and lower crystallinity are critical for improving the superconducting and electronic properties of Mg¹¹B₂ samples fabricated from the powder. Thus, the low-neutron-activation Mg¹¹B₂ is possibly an affordable and technically viable candidate to replace NbTi superconductors in the low field poloidal field and correction coils for the next-generation fusion reactors.