Phase-matching properties for AgGaGeS4

The phase-matching conditions of AgGaGeS(4) have been measured for second-harmonic generation at 0.8 and 5.3 microm, and difference-frequency generation at 2.2, 3.6-5.1, and 4.8-11.8 microm. The improved Sellmeier equations that reproduce well the various phase-matching conditions are presented.     

Light scattering from particles located under a rough dielectric layer

A discussion is presented of the effect of roughness on the detectability of subsurface particles by means of the light-scattering method. We have studied the scattering of light by calibrated spheres located under a slightly rough dielectric surface both experimentally and theoretically. In our experiments, the scattering from slightly rough layers with nonresonant particles was dominated by the roughness, and the scattering diagram did not bear any discernible indications of the spheres. However, at resonance, the subsurface particles manifested themselves by an increase in the total scattered intensity and by well-pronounced maxima in the angular dependence of both the scattering diagram and the backscattered intensity. Theoretical calculations show that the angular positions of the maxima in the scattering diagram are essentially determined by the interference of fields scattered by the particles and by the surface, whereas the contribution of the multiple interparticle scattering is negligible. By contrast, the oscillations in the angular dependence of the backscattered intensity are due primarily to the scattering between neighboring spheres.     

Testing the immunity of active implantable medical devices to CW magnetic fields up to 1 MHz by an immersion method

This paper presents a magnetic-field system and the method developed for testing the immunity of the active implantable medical devices to continuous-wave magnetic fields in the frequency range up to 1 MHz. The system is able to produce magnetic fields of 150 A/m for frequencies up to 100 kHz and strengths decreasing as 1/f between 100 kHz and 1 MHz, with uniformity of the field within +/-2.5% in the volume for tests. To simulate human tissue, the medical device, together with its leads, is placed on a plastic grid in a saline tank that is introduced in the magnetic field of the induction coil. This paper offers an alternative for the injection voltage methods provided in the actual standards for assessing the protection of the implantable medical devices from the effects of the magnetic fields up to 1 MHz. This paper presents the equipment and signals used, the test procedure, and results from the preliminary tests performed at the Food and Drug Administration-Center for Devices and Radiological Health on implantable pacemakers and neurostimulators. The new system and test method are useful for the EMC research on the implantable medical devices.     

Process design of waste gas treatment from Emirates Gold Refinery

In this case study, the process modifications and improvement to the existing process at the Emirates Gold refinery (in order to meet the United Arab Emirates (UAE) nitrogen oxides air emission regulations) is presented. In the past, Emirates Gold refinery used a single small scrubber to treat waste gases. In order to treat the waste gas efficiently, it was found that a cooled oxidation reactor (oxidizer) before the existing scrubber, as well as a second scrubber is needed. The waste gas is mixed with air at a fixed ratio before entering the oxidizer which is designed to obtain the optimum degree of NO oxidation (about 50%).To keep the oxidation reactions in the desirable direction the temperature should be kept between 15 and 20°C There for an internal cooler was required. The gas mixture from the Oxidizer enters the first scrubber (existing) where most of the NO _x , mainly as N₂O₃, are absorbed by a NaOH solution (15–20%). The remaining NO _x , mainly as N₂O₃ is absorbed in the second scrubber by a NaOH solution (8–10%). The mass transfer area of the packing in the two scrubbers, the solution circulation rate, and the cooling duty were designed to reach the desired degree of absorption of N₂O₃ and NO₂. This ensures that the recommended NO _x residual value of 500 mg/m³ (250 ppm) is reached. All reactions occur simultaneously was calculated using EQ4WIN software. The data obtained for different temperatures was processed with Stat View, SuperPro Designer simulation and Aspen HYSYS simulation.     

Update: An Efficient Synthesis of Poly(ethylene glycol)‐Supported Iron(II) Porphyrin Using a Click Reaction and its Application for the Catalytic Olefination of Aldehydes

The facile synthesis of polyethylene glycol (PEG)‐immobilized iron(II) porphyrin using a copper‐catalyzed azide‐alkyne [3+2] cycloaddition “click” reaction is reported. The prepared complex 5 (PEG‐C₅₁H₃₉FeN₇O) was found to be an efficient catalyst for the selective olefination of aldehydes with ethyl diazoacetate in the presence of triphenylphosphine, and afforded excellent olefin yields with high (E) selectivities. The PEG‐supported catalyst 5 was readily recovered by precipitation and filtration, and was recycled through ten runs without significant activity loss.     

Formaldehyde exposure at various workplaces

The results of formaldehyde determinations in the air at various workplaces in the period 1980-1988 are presented. The airborne concentrations varied between less than 0.01 and 10.9 mg m-3 (mean 0.7 mg m-3). For ambient air monitoring, active sampling and capillary gas chromatography are reliable and sensitive methods. Formic acid excretion in urine is an unspecific and insensitive biological indicator for monitoring low-dose formaldehyde exposure.     

The Chardonnay wine olfactory concept revisited: A stable core of volatile compounds, and fuzzy boundaries

An earlier study by the same team showed that Chardonnay wines have common olfactory properties by which wine experts can recognize them. The specific Chardonnay olfactory space was also tentatively linked to the relative concentrations of 29 volatile compounds, regarded as possible aroma-impact compounds. The question now is whether or not those initial results hold independently of the sample under consideration, that is, whether these sensory and chemical spaces are vintage-specific. A series of investigations was conducted on a new set of 46 wines (23 Chardonnay wines and 23 non Chardonnay wines) using the same sensory (wine typicality level) and physico-chemical (Gas Chromatography-mass spectrometry-selected ion monitoring: GC-MS-SIM) approaches as in the earlier study. The sensory space of Chardonnay wines has been identified again in this new study. Compared with white wines of other grape varieties, Chardonnay wines do have distinctive and recognizable olfactory characteristics. LSD tests carried out on the chemical data and a PLS analysis predicting wine typicality level from the chemical data showed that the relative concentrations of 35 volatile compounds affected the wines' typicality scores. Of the 35 compounds, 18 were already among the 29 possible aroma-impact compounds identified by the earlier study. These 18 common volatile compounds seem to be vintage-independent and as such might represent the core of the Chardonnay wine olfactory space. The others seem to be specific to the new wines tested and may contribute to the fuzziness of the boundaries of the Chardonnay wine olfactory space. These results emphasize the complexity of the odor quality of Chardonnay wines, with some volatile compounds remaining stable across vintages, while others are specific to enological practices and to vintages.     

Immobilization of Lipoxygenase,Catalase, and Lipase for a Reactor Design Targeting Linoleic Acid Hydroperoxidation

Hydroperoxy-9Z,11E-octadecadienoic acid (13-HPODE) can be obtained from safflower oil in an enzyme cascade utilizing lipase, lipoxygenase (LOX), and catalase for in situ oxygen generation. The application of immobilized enzymes may open a new path to a cost-efficient production of 13-HPODE, which is used for the synthesis of green note aroma hexanal. Ten immobilization supports are compared for immobilization of lipoxygenase-1 from Glycine max (LOX-1) and oxirane-based Immobead 150 P proves to be best with a maximum LOX-1 activity of 22 470 U g⁻¹. The immobilizate is successfully recycled in eight consecutive batches and maintains full activity over a period of 16 h using a 3D-printed column reactor. Catalase from Micrococcus lysodeikticus and LOX-1 are co-immobilized on Immobead 150 P allowing a constant production of 13-HPODE for up to six cycles with a maximum product conversion of 45% and a 13-regioselectivity of 83% . In this two-enzyme system with H₂O₂-dosage, foam generation is significantly reduced. Co-immobilization of LOX-1 and lipaseis possible; however, rapid lipase deactivation occurs. Therefore, a two-reactor approach with oil hydrolysis in the first reactor is proposed. Immobilized lipases from C. rugosa are suitable for safflower oil hydrolysis and maintain full activity over ten hydrolysis cycles. Practical applications: Linoleic acid hydroperoxide (13-HPODE) is the starting material for the synthesis of the green note aroma compound hexanal. The byproduct of the hydroperoxide splitting is ω-oxododecenoic acid, which is currently not employed industrially. The bifunctional oxodocecenoic acid is interesting as precursor for the synthesis of polymer building blocks. Simple one-step derivatization of the oxo-group can yield suitable C12 monomers such as dicarboxylic acids, ω-amino acids, or ω-hydroxy acids. Cost-efficiency is a key parameter to incorporate these new biobased building blocks for polymer applications. In this approach, immobilized enzymes are used for the synthesis of 13-HPODE starting from safflower oil with in situ oxygen generation to prevent excessive foam formation. A two-reactor concept is designed to circumvent hydroperoxide-induced lipase deactivation. Direct comparison of both batch and continuous process is performed and provides information for the implementation of the enzyme cascade and the design of an optimized reactor system.