Influence of nozzle area ratio on the gas-particle flow for single-hose dry ice blasting nozzle

Journal of Thermal Analysis and Calorimetry - In this paper, a numerical study was performed to examine the effect of divergent nozzle length of single-hose dry ice blasting on the development of...     

The effect of sterilization methods on the thermo-gelation properties of xyloglucan hydrogels

In this study, the influence of different sterilization methods on the thermo-gelation and structural properties of xyloglucan hydrogels was investigated. Xyloglucan samples were treated by either 70% ethanol, 70% isopropanol, γ-irradiation (10 kGy) at room temperature, γ-irradiation (10 kGy) in dry ice or autoclaving. These samples were tested for sterility by incubation with sterile Lysogeny Broth (LB) at room temperature, 30 °C and 37 °C for 30 days. According to the results obtained, xyloglucan hydrogels were only effectively sterilized by autoclaving or by γ-irradiation either at room temperature or in dry ice. These samples were analyzed by rheology measurements and dynamic and static light scattering analysis. Gamma-irradiation at room temperature markedly changed the polymer structure, preventing thermo-gelation. Only autoclaving and γ-irradiation in dry ice preserved the rheological properties of the polymer. The sol-gel transition as a function of the temperature was similar for these samples and the control sample.     

Dissociation behavior of “dry water” C_3H_8 hydrate below ice point:Effect of phase state of unreacted residual water on a mechanism of gas hydrates dissociation

The results on a dissociation behavior of propane hydrates prepared from "dry water" and contained unreacted residual water in the form of ice inclusions or supercooled liquid water(water solution of gas) were presented for temperatures below 273 K.The temperature ramping or pressure release method was used for the dissociation of propane hydrate samples.It was found that the mechanism of gas hydrate dissociation at temperatures below 273 K depended on the phase state of unreacted water in the hydrate sample.Gas hydrates dissociated into ice and gas if the ice inclusions were in the hydrate sample.The samples of propane hydrates with inclusions of unreacted supercooled water only(without ice inclusions) dissociated into supercooled water and gas below the pressure of the supercooled water-hydrate-gas metastable equilibrium.     

Onsager heat of transport for water vapour at the surface of water and ice: thermal accommodation coefficients for water vapour on a stainless-steel surface

The Onsager heat of transport Q* has been measured for water vapour at the surface of water, supercooled water, and ice, over the temperature range -8 to +10 degrees C. For liquid water, Q* is constant at -24.7 +/- 3.6 kJ mol(-1) (two standard deviations) over the pressure range 4-9.5 Torr. Provided the ice is suitably aged, the |Q*| values are very similar for water and ice, a result which is consistent with the presence of a liquid-like layer at the surface of ice. The values are slightly larger for ice, in proportion to the ratio of the heat of sublimation of ice to the heat of vaporization of the liquid. Departures from linearity of plots of P against DeltaT are attributed to temperature jumps at the surface of the dry upper plate. Hence jump coefficients and thermal accommodation coefficients have been derived as a function of temperature for collisions of water molecules with type-304 stainless steel.     

Oligomerisation anionique de l'ethylene—VII. Application a la synthese d'acides a longue chaine

Living oligomers of ethylene obtained with nBuLi complexed by tertiary amines, such as tetramethylethylene diamine (TMEDA), tetraethylethylenediamine (TEEDA) and pentamethyldiethylenetriamine (PMDT), have been deactivated by gaseous carbon dioxide or dry ice. The nuclear magnetic resonance study of the product has allowed study of the influence of the tertiary amine and the nature of the deactivation agent toward the functionalization. Two products have been characterized:

By increasing the ratio [tertiary amine]/[nBuLi] and using gaseous carbon dioxide instead of dry ice, one obtains a decrease of the functionalization.     

Facile and selective metalation of 7-dehydro-cholesterol (pro-vitamin D3)

Subsequent treatment of 7-dehydrocholesterol with trimethylsilylmethylpotassium in tetrahydrofuran, dry ice, mineral acid and diazomethane gives a regioisomerically pure, homoconjugated ester as a diastereomeric mixture, the minor component of which turns out to be thermodynamically more stable than a conjugated isomer.     

The effect of irradiation temperature on the quality improvement of Kimchi,Korean fermented vegetables,for its shelf stability

The present study was conducted to evaluate the effect of irradiation temperature on the shelf stability and quality of Kimchi during storage at 35 °C for 30 days. Kimchi samples were N₂-packaged and heated at 60 °C and then gamma irradiated at 20 kGy under various temperatures (room temperature, ice, dry ice, and liquid nitrogen). In the results of microbial, pH, and acidity analysis, combination treatment of heating and irradiation was able to sterilize microbes in Kimchi regardless of irradiation temperature. When Kimchi was irradiated under frozen temperatures, especially dry ice, the softening of texture and the deterioration of sensory quality of Kimchi were reduced. Also, ESR signal intensities were weakened due to the decrease of irradiation dose and temperature.     

Inelastic neutron scattering studies of the interaction between water and some amino acids

The interaction between water and some of amino acids (glycine, L-glutamine, L-threonine, L-cysteine and L-serine) was studied by inelastic incoherent neutron scattering (IINS). The vibrational spectra of dry amino acids and amino acids with a water content (e.g., 1 mol water/1 mol amino acid) were recorded. Comparing the difference spectra obtained by subtracting the spectrum of dry sample from those of wet sample with the spectra of ice Ih, we obtained that the difference spectrum for serine changed greatly from normal ice spectrum; but on the other hand, the difference spectra for the other amino acids such as glycine, glutamine, threonine, and cysteine changed slightly. The results demonstrate that serine has stronger hydrophilic character than glycine, glutamine, threonine, and cysteine. This is the first time the hydrophilic or hydrophobic character of amino acids was studied by using inelastic neutron scattering techniques, which provides important information for theoretical modeling and force field refinement for the interaction between water and the amino acids studied here.     

A convergent synthesis of the imidazopyridine scaffold of fluorescent alkaloid ageladine A

A convergent synthesis of the imidazopyridine scaffold of fluorescent alkaloid ageladine A (1) has been achieved, employing 3-amino-2-chloropyridine as the staring material. A carboxylic acid was introduced using n-butyllithium and dry ice as the key reaction.     

Novel Solventless Extraction Technique to Preserve Cannabinoid and Terpenoid Profiles of Fresh Cannabis Inflorescence

Despite its use by humans for thousands of years, the technology of cannabis usage and extraction is still evolving. Given that the primary pharmacological compounds of interest are cannabinoid and terpenoids found in greatest abundance in capitate glandular trichomes of unfertilized female inflorescences, it is surprising that older techniques of hashish making have received less technological advancement. The purpose of this study was to employ organically grown cannabis and to isolate pure trichomes from freshly picked flowers via exposure to vapor from solid CO₂, commonly known as “dry ice”, followed by their isolation via sifting through a 150 µ screens while maintaining the cold chain. Biochemical analysis was undertaken on fresh flower, frozen-sifted flower by-products, treated trichomes (Kryo-Kief™), dried flower, dried sifted flower by-product and dried kief. The dry ice process successfully concentrated cannabinoid content as high as 60.7%, with corresponding concentration and preservation of monoterpenoids encountered in fresh flower that are usually lost during the conventional cannabis drying and curing process. The resulting dried sifted flower by-product after dry ice processing remains a usable commodity. This approach may be of interest to pharmaceutical companies and supplement producers pursuing cannabis-based medicine development with an eye toward full synergy of ingredients harnessing the entourage effect.     

New Glassware for Small-Scale Distillation

Distillation of less than a ml of sample can be accomplished with a jacketed Hickman still. The jacket allows positioning of a coolant such as dry ice/acetone at the site of desired condensation. A jacketed distillation head will accommodate samples up to a volume of 3 ml. Distillate is easily removed with a Pasteur pipette. Details of the glassware design are given.     

Analytical investigation of simultaneous effects of convergent section heating of Laval nozzle,steam inlet condition,and nozzle geometry on condensation shock

Rapid expansion and supercooling of dry vapor in low-pressure steam turbines trigger nucleation phenomenon. Subsequently, following the occurrence of vapor condensation, a vapor–liquid two-phase flow is established. Entropy generation mainly by condensation shock, blade erosion, and ultimately, destruction of equipment and efficiency reduction are among adverse effects of vapor condensation, which should be either attenuated or controlled. In the present research, which is a continuation to the research performed by original authors, a one-dimensional analytical Eulerian–Lagrangian model is used to apply convergent section heating to different supersonic nozzles under various inlet conditions. The results indicate that the flow response to the heating is well dependent on the intensity of condensation shock or inlet conditions. In order to compensate for the mass flow rate resulted from the convergent section heating, effects of simultaneous reduction of inlet stagnation temperature and convergent section heating were investigated. Finally, it was found that, maintaining constant mass flow rate, simultaneous reduction of inlet stagnation temperature and convergent section heating cannot attenuate the condensation shock significantly. Therefore, the best approach to compensate for the reduction in the mass flow rate due to convergent section heating is to simultaneously increase inlet stagnation pressure.     

Formal Synthesis of (±)‐Isodihydronepetalactone

A formal synthesis of (±)‐isodihydronepetalactone ( 1 ) from cyclobutenone 5 was de scribed. Baeyer‐Villiger lactonization of cyclobutanone 8 followed by decholorination led to lactone 4 , which under went a series of functional group trans formations, furnished cyclopentanone derivative 15 . Shapiro reaction on hydrazone derivative in the presence of excess dry ice gave lactone 2 . Lactone 2 had previously been converted to isodihydronepetalactone ( 1 ).     

Phase changes of CO2 hydrate under high pressure and low temperature

High pressure and low temperature experiments with CO(2) hydrate were performed using diamond anvil cells and a helium-refrigeration cryostat in the pressure and temperature range of 0.2-3.0 GPa and 280-80 K, respectively. In situ x-ray diffractometry revealed that the phase boundary between CO(2) hydrate and water+CO(2) extended below the 280 K reported previously, toward a higher pressure and low temperature region. The results also showed the existence of a new high pressure phase above approximately 0.6 GPa and below 1.0 GPa at which the hydrate decomposed to dry ice and ice VI. In addition, in the lower temperature region of structure I, a small and abrupt lattice expansion was observed at approximately 210 K with decreasing temperature under fixed pressures. The expansion was accompanied by a release of water content from the sI structure as ice Ih, which indicates an increased cage occupancy. A similar lattice expansion was also described in another clathrate, SiO(2) clathrate, under high pressure. Such expansion with increasing cage occupancy might be a common manner to stabilize the clathrate structures under high pressure and low temperature.     

Analysis of monomeric alkyl- and arylchlorosilanes

The radioisotope carbon-14 was used to study the retention of carbon in the decomposition of alkyl- and arylchlorosilanes by wet methods. Losses by sample volatilisation were overcome by preliminary cooling in dry ice. Fuming sulphuric acid alone or in mixtures with fuming nitric acid was found to be the most effective oxidant of the acids tested. Examination of the carbon-containing silica residues by X-ray powder photography indicated that amorphous carbon was present but there was no evidence of silicon carbide.     

In-adamantane, a small inside-out molecule

The hydrocarbon in-adamantane (1), a high-energy adamantane isomer in which one methine hydrogen atom is inside the cage, is predicted by ab initio calculations to be isolable at dry ice temperature. It has 440 kJ/mol of hydrogenic strain but appears to be stable against dimerization, moisture, and air. The inverted CH bond is compressed, and the IR and NMR spectra are unusual. The symmetrical pentadecafluoro derivative (2) has an estimated half-life of 100 years at room temperature.     

Determination of locust bean gum and guar gum by polymerase chain reaction and restriction fragment length polymorphism analysis

A polymerase chain reaction (PCR) was developed to differentiate the thickening agents locust bean gum (LBG) and the cheaper guar gum in finished food products. Universal primers for amplification of the intergenic spacer region between trnL 3' (UAA) exon and trnF (GAA) gene in the chloroplast (cp) genome and subsequent restriction analysis were applied to differentiate guar gum and LBG. The presence of <5% (w/w) guar gum powder added to LBG powder was detectable. Based on data obtained from sequencing this intergenic spacer region, a second PCR method for the specific detection of guar gum DNA was also developed. This assay detected guar gum powder in LBG in amounts as low as 1% (w/w). Both methods successfully detected guar gum and/or LBG in ice cream stabilizers and in foodstuffs, such as dairy products, ice cream, dry seasoning mixes, a finished roasting sauce, and a fruit jelly product, but not in products with highly degraded DNA, such as tomato ketchup and sterilized chocolate cream. Both methods detected guar gum and LBG in ice cream and fresh cheese at levels <0.1%.     

Development of a new QuEChERS method based on dry ice for the determination of 168 pesticides in paprika using tandem mass spectrometry

This study describes a new QuEChERS method referred to as the dry ice-partitioning QuEChERS method. This current method can be differentiated from the other QuEChERS methods in the sense that it uses dry ice rather than salts or buffers to extract and partition pesticides in the first extraction step. The dry ice-partitioning QuEChERS method consists of extraction method A (for detection of the acetonitrile layer) and extraction method B (for detection of both acetonitrile and aqueous layers). The extraction efficiency was then compared with the citrate-buffering QuEChERS method by means of recovery. Recovery values of the tested 168 pesticides were above 76%, with relative standard deviations of less than 20%. Certain problematic pesticides, including benfuracarb, carbosulfan, dichlofluanid, probenazole, pymetrozine, tolylfluanid, TFNA, and TFNG evidenced acceptable recoveries via the dry ice-partitioning QuEChERS method compared to the less than 70% recoveries of the citrate-buffering QuEChERS method examined herein. The matrix effect of paprika on the method developed herein was not significant, and matrix-matched calibration was performed well, with an r(2)≥0.99. The dry ice-partitioning QuEChERS method is capable of detecting the aqueous layer as well as the acetonitrile layer; this interesting feature makes it worth in application as an alternative QuEChERS method for the multiresidue analysis of pesticides within a broad polarity range in various matrices.     

The determination of organotin compounds in edible oils by gas chromatography-atomic absorption spectrometry

An extraction method for butyl-, cyclohexyl-, octyl- and phenyltin compounds from edible oils was developed using 0.05% tropolone in 0.04M HCl/methanol. Cooling the methanol extracts in a dry ice/methanol bath removed approximately 64% of nonvolatile coextractives without affecting recoveries. Methyl derivatives formed by Grignard reaction were quantitated by gas chromatography-atomic absorption spectrometry. Edible oils sold in poly(vinyl chloride) containers had ng/g levels of dioctyl- and monooctyltin. GCMS confirmed the presence of octyltin and did not detect any other organotin compounds in the extracts.     

Formal Synthesis of (±)-Mitsugashiwalactone and (±)-Isodihydronepetalactone from Norborn-5-en-2-one Involving Shapiro Reaction

A formal synthesis of (±)-mitsugashiwalactone ( 1 ) and (±)-isodihydro nepetalactone ( 2 ) was accomplished. Baeyer-Villiger lactonization of ketone 9 followed by acidic treatment led to the rearranged lactone 8 , which underwent a series of functional group transformations to give cyclopentanone derivatives 19 and 20 . Shapiro reaction on 21 and 22 in the presence of excess dry ice gave lactones 5 and 6 . Lactones 5 and 6 previously have been converted to mitsugashiwalactone ( 1 ) and isodihydronepetalactone ( 2 ), respectively.