Ultrasound technology for food fermentation applications

Fermentation processes involve the participation of enzymes and organic catalysts, generated by range of microorganisms to produce chemical transformations. Ultrasound can be used in such processes to either monitor the progress of fermentation or to influence its progress. High frequency ultrasound (>2 MHz) has been extensively reported as a tool for the measurement of the changes in chemical composition during fermentation providing real time information on reaction progress. Low frequency ultrasound (20–50 kHz) can influence the course of fermentation by improving mass transfer and cell permeability leading to improved process efficiency and production rates. It can also be used to eliminate micro-organisms which might otherwise hinder the process. This review summarises key applications of high and low frequency ultrasound in food fermentation applications.     

Ultrasound in natural products synthesis: applications to the synthesis of histrionicotoxin via nitroalkanal acetals

Ultrasound promoted the Kornblum reaction of silver nitrite or sodium nitrite with haloalkyl acetals to afford the corresponding C-nitro compounds. The acetalprotected nitro compounds were used as reactants in a 'double Henry' reaction to produce the key intermediate nitrocyclohexane diol with a masked aldehyde side chain. The nitrodiol was then subjected to an ultrasound-promoted one-pot/single operation sequence involving a reduction deprotection followed by a cyclization-reduction. The entire sequence provided the core spiropiperidine substructure of the histrionicotoxins.     

Ultrasound irradiation as an effective tool in synthesis of the slag-based catalysts for carboxymethylation

Waste minimization strategy was applied in the current work for synthesis of the catalysts from industrial solid waste, namely desulfurization slag. The starting slag material comprising CaCO₃, Ca(OH)₂, SiO₂, Al₂O₃, Fe₂O₃, and TiO₂ was processed by various treating agents systematically varying the synthesis parameters. A novel efficient technique – ultrasound irradiation, was applied as an additional synthesis step for intensification of the slag dissolution and crystallization of the new phases. Physico-chemical properties of the starting materials and synthesized catalysts were evaluated by several analytical techniques. Treatment of the industrial slag possessing initially poor crystal morphology and a low surface area (6 m²/g) resulted in formation of highly-crystalline catalysts with well-developed structural properties. Surface area was increased up to 49 m²/g. High basicity of the neat slag as well as materials synthesized on its basis makes possible application of these materials in the reactions requiring basic active sites. Catalytic performance of the synthesized catalysts was elucidated in the synthesis of carbonate esters by carboxymethylation of cinnamyl alcohol with dimethyl carbonate carried out at 150 °C in a batch mode. Ultrasonication of the slag had a positive effect on the catalytic activity. Synthesized catalysts while exhibiting similar selectivity to the desired product (ca. 84%), demonstrated a trend of activity increase for materials prepared using ultrasonication pretreatment. The choice of the treating agent also played an important role in the catalytic performance. The highest selectivity to the desired cinnamyl methyl carbonate (88%) together with the highest activity (TOF₃₅ = 3.89*10⁻⁷ (mol/g*s)) was achieved over the material synthesized using 0.6 M NaOH solution as the treating agent with the ultrasound pre-treatment at 80 W for 4 h.     

Emerging applications of wavelets: A review

Although most of its popular applications have been in discrete-time signal processing for over two decades, wavelet transform theory offers a methodology to generate continuous-time compact support orthogonal filter banks through the design of discrete-time finite length filter banks with multiple time and frequency resolutions. In this paper, we first highlight inherently built-in approximation errors of discrete-time signal processing techniques employing wavelet transform framework. Then, we present an overview of emerging analog signal processing applications of wavelet transform along with its still active research topics in more matured discrete-time processing applications. It is shown that analog wavelet transform is successfully implemented in biomedical signal processing for design of low-power pacemakers and also in ultra-wideband (UWB) wireless communications. The engineering details of analog circuit implementation for these continuous-time wavelet transform applications are provided for further studies. We expect a flurry of new research and technology development activities in the coming years utilizing still promising and almost untapped analog wavelet transform and multiresolution signal representation techniques.     

kltool: A tool to analyze spatiotemporal complexity

We announce the availability of a software package, called kltool, that can extract phase space information from complex spatiotemporal data via the Karhunen-Loeve analysis. Data generated by the periodic, quasiperiodic or chaotic evolution of a small number of spatially coherent structures can be processed. A key feature of kltool is that it allows the user to interact easily with the data processing and its graphical display. We illustrate the use of kltool on numerical data from the Kuramoto-Sivashinsky equation and laboratory data from a flame experiment.     

Intrastate γ-transitions: A spectroscopic tool?

In the framework of a potential model we have calculated the various bremsstrahlung cross sections into the⁵Li ground state, includingM 1 andE 2 γ-transitions leading from the high energy wing of the⁵Li ground state resonance into states belonging to the same resonance at lower energy (intrastate transition). Our calculation supports the hypothesis of Schmalbrock et al. [1] that intrastate transitions ofM 1 andE 2 multipolarity exist. While we find a maximum cross section of roughly 1.4 nb for theE 2 transition, we predict the cross sections forM 1 intrastate transition to be less than 3·10^?5nb. An experimental observation of the intrastate γ-ray emission appears to be very difficult due to the dominance of competing resonant (M 1) and direct (E 1) capture processes. Schmalbrock et al. have suggested to deduce magnetic dipole and electric quadrupole moments of resonant states from the measurements of the respectiveM 1 andE 2 intrastate transitions. We will show that theM 1 intrastate cross sections do not yield the appropriate information to determine the magnetic dipole moment. We will also discuss thatE 2 intrastate transitions do not seem to be a suited tool to find the quadrupole moment of an unstable state.     

Medical applications of infrared thermography: A review

Abnormal body temperature is a natural indicator of illness. Infrared thermography (IRT) is a fast, passive, non-contact and non-invasive alternative to conventional clinical thermometers for monitoring body temperature. Besides, IRT can also map body surface temperature remotely. Last five decades witnessed a steady increase in the utility of thermal imaging cameras to obtain correlations between the thermal physiology and skin temperature. IRT has been successfully used in diagnosis of breast cancer, diabetes neuropathy and peripheral vascular disorders. It has also been used to detect problems associated with gynecology, kidney transplantation, dermatology, heart, neonatal physiology, fever screening and brain imaging. With the advent of modern infrared cameras, data acquisition and processing techniques, it is now possible to have real time high resolution thermographic images, which is likely to surge further research in this field. The present efforts are focused on automatic analysis of temperature distribution of regions of interest and their statistical analysis for detection of abnormalities. This critical review focuses on advances in the area of medical IRT. The basics of IRT, essential theoretical background, the procedures adopted for various measurements and applications of IRT in various medical fields are discussed in this review. Besides background information is provided for beginners for better understanding of the subject.     

A speckle-shearing interferometer: A tool for measuring derivatives of surface displacements

A speckle-shearing interferometer is developed using a sheared Michelson interferometer. The tool, like speckle interferometry, utilizes the speckle effect of coherent light. However, while speckle interferometry measures surface displacements, the speckle-shearing interferometer determines the derivatives of the surface displacements. Hence, it eliminates the necessity of differentiating the measured displacements to obtain strain.     

Ultrasound accelerated Claisen-Schmidt condensation: A green route to chalcones

Chalcones have been synthesized under sonochemical irradiation by Claisen-Schmidt condensation between benzaldehyde and acetophenone. Two basic activated carbons (Na and Cs-Norit) have been used as catalysts. The effect of the ultrasound activation has been studied. A substantial enhancing effect in the yield was observed when the carbon catalyst was activated under ultrasonic waves. This “green” method (combination of alkaline-doped carbon catalyst and ultrasound waves) has been applied to the synthesis of several chalcones with antibacterial properties achieving, in all cases, excellent activities and selectivities. A comparative study under non-sonic activation has showed that the yields are lower in silent conditions, indicating that the sonication exerts a positive effect on the activity of the catalyst. Cs-doped carbon is presented as the optimum catalyst, giving excellent activity for this type of condensation. Cs-Norit carbon catalyst can compete with the traditional NaOH/EtOH when the reaction is carried out under ultrasounds. The role of solvent in this reaction was studied with ethanol. High conversion was obtained in absence of solvent. The carbons were characterized by thermal analysis, nitrogen adsorption and X-ray photoelectron spectroscopy.     

Ion implantation: A useful tool for semiconductor research

The general features of ion implantation are described in a brief survey to illustrate the usefulness of, and the new possibilities for, semiconductor research provided by implantation of high-energy ions. The advantages for research are explained by presenting examples which make use of the special features of implantation. Macroscopic properties are distinguished from the microscopic ones. Macroscopic properties are, for instance, the doping profile obtained, the flexibility in the choice of the implanted impurity, and the chemical, elastical and optical effects of the radiation damage. Microscopic properties are the various states of incorporation of the impurities after implantation, the interaction of the impurities with radiation defects, and the anomalous diffusion observed.     

Crossed gratings: A theory and its applications

We introduce a rigorous formulation for the problem of the diffraction by a finitely-conducting, bi-periodic surface. The formationon is based on a coordinate transformation which maps the grating surface onto a plane. The transformed Maxwell equations are resolved using an iterative technique. The numerical implementation is tested against a number of criteria, including a comparison with two recently developed formalisms. As well, it is shown to give results in agreement with the Reciprocity Theorem, which is derived for efficiencies of crossed gratings in unpolarized light. The method has been shown to work throughout the whole range of values of surface conductivity. We investigate the effect of a surface-corrugation on the solar absorptance of a metallic mirror. We discuss a useful equivalence property linking the behaviour of crossed gratings with that of classical gratings. We exhibit for the first time a grating in a highly-reflecting metal capable of totally absorbing unpolarized incident light. On leave from the Department of Theoretical Physics, School of Physics, University of Sydney, Sydney, N.S.W., 2006, Australia     

A scheme to realize time-bin entanglement between two photons that never interacted

We propose a scheme of entangling two photons from two separated sources. Our proposal which is inspired by the time-bin entanglement developed recently, provides a novel alternative for revealing contradiction between quantum nonlocality and local realism based on two independent single photon sources.     

Ultrasound for microalgal cell disruption and product extraction: A review

Microalgae are a promising feedstock for the production of biofuels, nutraceuticals, pharmaceuticals and cosmetics, due to their superior capability of converting solar energy and CO₂ into lipids, proteins, and other valuable bioactive compounds. To facilitate the release of these important biomolecules from microalgae, effective cell disruption is usually necessary, where the use of ultrasound has gained tremendous interests as an alternative to traditional methods. This review not only summarizes the mechanisms of and operation parameters affecting cell disruption, but also takes an insight into measuring techniques, synergistic integration with other disruption methods, and challenges of ultrasonication for microalgal biorefining. Optimal conditions including ultrasonic frequency, intensity, and duration, and liquid viscosity and sonochemical reactor are the key factors for maximizing the disruption and extraction efficiency. A combination of ultrasound with other disruption methods such as ozonation, microwave, homogenization, enzymatic lysis, and solvents facilitates cell disruption and release of target compounds, thus provides powerful solutions to commercial scale-up of ultrasound extraction for microalgal biorefining. It is concluded that ultrasonication is a sustainable “green” process, but more research and work are needed to upscale this process without sacrificing performance or consuming more energy.     

Geometric calculus: A new computational tool for Riemannian geometry

We compare geometric calculus applied to Riemannian geometry with Cartan's exterior calculus method. The correspondence between the two methods is clearly established. The results obtained by a package written in an algebraic language and doing general manipulations on multivectors are compared. We see that the geometric calculus is as powerful as exterior calculus.     

A new tool for painting diagnostics: Optical coherence tomography

Nondestructive techniques have seen successful growth in the last few years, and, among them, optical ones are widespread and extremely well received in the field of painting diagnostics because of their effectiveness and safety. At present, many techniques for nondestructive investigations of paintings are available; nevertheless, none of them is suitable for a quantitative characterization of varnish. However, varnish removal, either partial or complete, is a fundamental part of the cleaning process, which is an essential step in painting conservation. This critical process has been carried out, up to now, without the possibility of any non-destructive measurement for assessing the actual varnish thickness, but with microscopic observation of a detached microfragment. Optical coherence tomography (OCT) is a noninvasive technique that is well established for biomedical applications. In this work, we present a novel application of OCT to measure the varnish film thickness for painting diagnostics. The text was submitted by the authors in English.     

Classical trajectories: A powerful tool for solving tunneling problems

In the realm of Ehrenfest’s theorem, classical trajectories obeying Newton’s laws have been proven useful to construct explicit solutions to the time-dependent Wigner–Liouville equation. Whereas previous works have particularly focused on the initial distribution function as a vehicle found to carry the signatures of quantum statistics into the time-dependent solution, the present paper shows that the Lagrange–Charpit method based on classical trajectories can be successfully invoked as well to tackle quantum mechanical features with no classical counterpart, such as tunneling.     

Plasmonic nanoparticles and their analytical applications: A review

Plasmonic nanoparticles (NPs) have been reviewed herein for their fascinating optical properties in a wide spectral range and for their various applications. The surface plasmon resonance (SPR) bands of metal NPs can be tuned from visible to near infrared region by varying the shape of the metal NPs. As a result, the tuning of the SPR band over a spectral range is possible by making plasmonic NPs of different shapes. This review emphasizes fundamental studies of plasmonic NPs and nanocomposites with well-defined and controlled shapes that have several analytical applications such as molecular detection and determination in different fields. This review describes how oxidative etching and kinetic control can be utilized to manipulate the shape and optical properties of NPs. This review also describes the specific examples of the sensing applications of the localized surface plasmon resonance studies in which the researchers use both wavelength shift and surface-enhanced Raman scattering sensing to detect the molecules of chemical and biological relevance. The review ends with a perspective of the field, identifying the main challenges to be overcome and suggesting areas where the most promising developments are likely to happen in future.