External-cavity semiconductor laser with 15 nm continuous tuning range

A 1.26 ?m optical amplifier with a facet modal reflectivity below 0.0001 has been used in a 58 mm-long grating external cavity. The lasing wavelength has been continuously tuned without mode hopping over a range of 15 nm by combined translation-rotation of the diffraction grating. A linewidth of 20 kHz has been derived from heterodyne beat frequency measurements between two tunable external-cavity lasers.     

Effects of low-intensity ultrasound on the central nervous system of primates

The brains of anesthesized squirrel monkeys were exposed to 2.25 to 5 MHz ultrasound at low intensities (average power from 3 mW/cm2 to 0.9 W/cm2). The exposure produced evoked potentials recorded by EEG electrodes chronically implanted in the midline parietal region. Computer analysis of the waveforms showed that ultrasound produced a transient upward shift in both the peak frequency and in its amplitude. Complete adaptation occurred with 3 min of continuous exposure to either CW or pulsed irradiation.     

A comparative analysis of pulmonary perfusion scans with pulmonary angiograms

Pulmonary angiograms and pulmonary lung perfusion scans on 162 patients with pulmonary embolism were comparatively analyzed. Among the expert angiographic panel members who independently evaluated the studies there was consistent agreement on the diagnosis, size of the emboli, and severity. Consistency of agreement among the expert pulmonary lung perfusion scan panelists was considerably less. These data demonstrate that, in addition to the lack of specificity of the lung perfusion scan for the diagnosis of pulmonary thromboemboli, there is a considerable problem of interpretation in this patient population.     

Special Feature: Prometheus or Pandora: The Influence of Automation on Society

Even though computer technology may challenge one of man's last and most cherished illusions—that he alone is capable of thought—it can also show him how to live in harmony with nature.     

Phytochemical composition and antioxidant capacity of various botanical parts of the fruits of Prunus × domestica L. from the Lorraine region of Europe

Mirabelle plums represent a famous fruit from the Lorraine region, however little is known about their phytochemical composition. The oil of the fruit contained predominantly oleic acid (59%) and linoleic acid (29%). The total content of phenolic antioxidants in the whole fruits was 5.338 g/kg with 456 mg/kg (9%), 701 mg/kg (13%) and 4159 mg/kg (78%) detected in the peels, flesh and pits respectively. The peels contained solely 3,4-dihydroxybenzoic acid (270 mg/kg) and rutin (186 mg/kg), the flesh exclusively echinoids (723 mg/kg), whereas the pits contained a rich variety of phenolic compounds (4.2 g/kg) dominated by amygdalin (3.8 g/kg), but with significant contributions from vanillin (102 mg/kg), guajacyl-glycerin-coniferyl aldehyde isomers (87 mg/kg), dehydro-diconiferyl aldehyde (52 mg/kg), and vanillin diglucoside (48 mg/kg). Of the major phenolic compounds tested across a range of in vitro assays, rutin was the superior antioxidant.     

Critical assessment of methods for measurement of temperature profiles and heat load history in microwave heating processes—A review

Limitations of microwave processing due to inhomogeneities of power input and energy absorption have been widely described. Over- and underheated product areas influence reproducibility, product quality, and possibly safety. Although a broad range of methods is available for temperature measurement and evaluation of time/temperature effects, none of them is sufficiently able to detect temperature differences and thermally induced effects within the product caused by inhomogeneous heating. The purpose of this review is to critically assess different methods of temperature measurement for their suitability for different microwave applications, namely metallic temperature sensors, thermal imaging, pyrometer measurement, fiber optic sensors, microwave radiometry, magnetic resonance imaging, liquid crystal thermography, thermal paper, and biological and chemical time-temperature indicators. These methods are evaluated according to their advantages and limitations, method characteristics, and potential interference with the electric field. Special attention is given to spatial resolution, accuracy, handling, and purpose of measurement, that is, development work or online production control. Differences of methods and examples of practical application and failure in microwave-assisted food processing are discussed with a special focus on microwave pasteurization and microwave-assisted drying. Based on this assessment, it is suggested that infrared cameras for measuring temperature distribution at the product surface and partially inside the product in combination with a chemical time/temperature indicator (e.g., Maillard reaction, generating heat-induced color variations, depending on local energy absorption) appear to be the most appropriate system for future practical application in microwave food process control, microwave system development, and product design. Reliable detection of inhomogeneous heating is a prerequisite to counteracte inhomogeneity by a targeted adjustment of process and product parameters in microwave applications.     

Simultaneous fractionation of multiple classes of polyphenols from honeybush tea using solid-phase extraction

The structural diversity of polyphenols and the inherent limitations of current extraction techniques pose a challenge to extract polyphenols using a simple and green method. Hence, in this study, a method was developed to simultaneously fractionate multiple classes of polyphenols by only varying ethanol-water solutions. Honeybush tea, which is rich in polyphenols, was selected as a model for this study. Solvent extraction followed by solid-phase extraction (SPE) was developed to obtain a polyphenol-rich fraction from six honeybush samples. Based on a gradient elution programme (10%, 30%, 50%, 70% and 90% (v/v) ethanol-water solution) of SPE, the Strata X cartridge showed a better recovery of most targeted polyphenols under 0.9 mL of the drying volume and 1 mL min⁻¹ of the dispensing speed. The elution programme for fractionating most polyphenols was as follows: single elution with 50% ethanol, followed by twice elution with 70% ethanol. The antioxidant capacity was used to analyse the differences among the polyphenol-rich fractions from six honeybush samples. Principal component analysis (PCA) revealed that unfermented C. genistoides (GG) has the greatest antioxidant capacity among the honeybush species studied. Additionally, mangiferin, isomangiferin and vicenin-2 were the main contributors to the antioxidant capacity in six honeybush fractions according to the correlation study.