Accurate determination of polyethylene pellet density using transmission Raman spectroscopy

In this study, transmission Raman spectroscopy was explored for the direct measurement of the density of packed polyethylene (PE) pellets. A simple and direct transmission Raman measurement of packed, solid granules or pellet samples without pretreatment is greatly advantageous. Initially, the optimal packing thickness of PE pellets for transmission Raman measurement was determined by investigating the reproducibility of triplicate spectra collected by varying the thickness from 2 to 9 cm. Once determined, transmission Raman spectra were collected for 25 different grades of PE pellets and the partial least squares method was used to determine the sample density. The resulting accuracy was 0.00067 g·cm⁻³, while that obtained using backscattering measurements was 0.00083 g·cm⁻³. To investigate possible inhomogeneity within a pellet, Raman line mapping was performed over the face of a sectioned pellet and spectral variations among the mapped spectra were examined using principal component analysis. In addition, differential scanning calorimetry was performed on three samples prepared separately by cutting a pellet into left, middle, and right sections. Based on both studies, internal pellet inhomogeneity was found to be minute, but was clearly present. The correct sample representation of internally inhomogeneous PE pellets by the transmission Raman measurement eventually improved the accuracy for density determination. Finally sample‐to‐sample two‐dimensional correlation analysis was used to further examine the origin of the improved accuracy. Copyright © 2011 John Wiley & Sons, Ltd.     

Parameters and properties of crystals of ionic compounds obtained by centrifugal separation of supersaturated aqueous solutions

The change in the chemical composition, structural parameters, and properties of Ba(NO₃)₂, PbCl₂, and KI crystals and the binary alkali-halide systems LiCl-KCl (eutectic) and LiCl-NaCl and KCl-KI (solid solutions) after centrifugal separation under acceleration (1.3, 6.2, 11.8)×10³ g is investigated. The composition variation was monitored by the methods of chemical gravimetric and titration analyses, as well as of flame-photometric and spectrophotometric analyses. Acceleration causes a change in the chemical composition, lattice parameter, refractive index, and microhardness in all systems as compared to the initial values. It is found that centrifugation affects the systems with different masses of cations more strongly than the systems with different masses of anions. A criterion of the ratio of the masses of ions (cations and anions) rat i/i is proposed for predicting the effect of centrifugation on the change in the chemical composition and properties of compounds and their systems (a larger value of this ratio leads to a stronger variation of the composition and properties). The crystals of all compounds and solid solutions display an increase in microinclusions (visible only in transmitted light) upon an increase in the acceleration. The lattice parameters and microhardness measured in KCl and KBr crystals four years after their fabrication by using centrifugal separation indicate a considerable return to their initial values.     

A pellet tracking system for the PANDA experiment

Frozen microspheres of hydrogen (pellets) will be one of the target types for the future hadron physics experiment PANDA at FAIR (GSI, Darmstadt, Germany) [1]. Pellets with a diameter of 25– μm are generated about 3 meters above the interaction region, to which they travel with a velocity around 80 m/s inside a narrow pipe. The interaction region is defined by the overlap of the pellet stream and the accelerator beam and has a size of a few millimeters. One would like to know the interaction point more precisely, to have better possibilities to reconstruct particle tracks and events e.g. in charmonium decay studies. One would also like to suppress background events that do not originate in a pellet, but e.g. may occur in rest gas, that is present in the beam pipe. A solution is provided by the presented pellet tracking system together with a target operation mode that provides one and only one pellet in the interaction region most of the time. The goal is to track individual pellets in order to know their position with a resolution of a few tenths of a millimeter at the time of an interaction. The system must also be highly efficient and provide tracking information for essentially all pellets that pass the interaction region. Presented results from the design studies show that the goals can be fulfilled by this solution.     

Organic-solvent-free extraction of carotenoids from yeast Rhodotorula glutinis by application of ultrasound under pressure

The extraction of Rhodotorula glutinis carotenoids by ultrasound under pressure (manosonication) in an aqueous medium has been demonstrated. The influence of treatment time, pressure, and ultrasound amplitude on R. glutinis inactivation and on the extraction of carotenoids was evaluated, and the obtained data were described mathematically. The extraction yields were lineal functions of those three parameters, whereas inactivation responded to a more complex equation. Under optimum treatment conditions, 82% of carotenoid content was recovered. Extraction of carotenoids in an aqueous medium was attributed to the capacity of ultrasound for cell disruption and emulsification. Cavitation caused the rupture of cell envelopes and the subsequent formation of small droplets of carotenoids surrounded by the phospholipids of the cytoplasmic membrane that would stabilize the emulsion. Analysis of the dispersed particle size of the extracts demonstrated that a fine, homogeneous emulsion was formed after treatment (average size: 230 nm; polydispersity <0.22). This research describes an innovative green process for extracting carotenoids from fresh biomass of R. glutinis in which only two unit operations are required: ultrasonic treatment, followed by a centrifugation step to discard cell debris. The extract obtained thanks to this procedure is rich in carotenoids (25 mg/L) and could be directly incorporated as a pigment in foods, beverages, and diet supplements; it can also be utilized as an ingredient in drugs or cosmetics.     

Using ultrasound Nakagami imaging to assess liver fibrosis in rats

This study explored the feasibility of using the ultrasound Nakagami image to assess the degree of liver fibrosis in rats. The rat has been widely used as a model in investigations of liver fibrosis. Ultrasound grayscale imaging makes it possible to observe fibrotic rat livers in real time. Statistical analysis of the envelopes of signals backscattered from rat livers may provide useful clues about the degree of liver fibrosis. The Nakagami-model-based image has been shown to be useful for characterizing scatterers in tissues by reflecting the echo statistics, and hence the Nakagami image may serve as a functional imaging tool for quantifying rat liver fibrosis. To validate this idea, fibrosis was induced in each rat liver (n = 21) by an intraperitoneal injection of 0.5% dimethylnitrosamine. Livers were excised from rats for in vitro ultrasound scanning using a single-element transducer. The backscattered-signal envelopes of the acquired raw ultrasound signals were used for Nakagami imaging. The Metavir score determined by a pathologist was used to histologically quantify the degree of liver fibrosis. It was found that the Nakagami image could be used to distinguish different degrees of liver fibrosis in rats, since the average Nakagami parameter increased from 0.55 to 0.83 as the fibrosis score increased from 0 (i.e., normal) to 4. This correlation may be due to liver fibrosis in rats involving an increase in the concentration of local scatterers and the appearance of the periodic structures or clustering of scatterers that would change the backscattering statistics. The current findings indicate that the ultrasound Nakagami image has great potential as a functional imaging tool to complement the use of the conventional B-scan in animal studies of liver fibrosis.     

Seminal freezing in pure breed andalusian horse: difference in individual stallions and correlation between pre and post-freezing sperm parameters

The aim of this study was the optimization of the sperm freezing protocols for the Pure Breed Andalusian Horse (AH) stallions. The study was performed in 84 ejaculates from 14 stallions (6 ejaculates per stallion). We examined the effect of individual stallion, centrifugal force and centrifugation extender on post-thaw sperm quality. Neither centrifugal force nor centrifugal extender had any significant effect on post-centrifugation or post-thawing sperm quality. Stallion was the principal source of variation in our experiments, showing individual significant differences (p < 0.05) in all parameters. Individual differences were more extreme prior to freezing than after freezing-thawing. There are significant positive correlations (p < 0.05 and p < 0.01) between all post-centrifugation and post-thawing parameters.     

Novel insights into controlled drug release from coated pellets by confocal Raman microscopy

The development of novel therapeutics with improved efficacy implies increasing complexity of drug delivery systems, which in turn require advanced methods for their analytical characterization. Among these systems, pellets represent upcoming carrier systems, which show several advantages like simplified dosing and improved compliance among children and the aged population. However, rational development of such systems is hampered by the lack of non‐destructive, chemically selective analytical insight into compound distribution and drug release mechanisms. The aim of this study was to evaluate confocal Raman microscopy (CRM) for investigation of coated drug‐loaded pellets based on visualization of compound distribution and elucidation of drug release mechanisms. Three complementary approaches were applied for pellet characterization: analysis of cross sections after bisectioning, non‐invasive visualization of the pellet surface, and virtual cross sectioning in x–z direction. As the surface of such pellets is structured, a complementary approach of optical topography and CRM was applied for three‐dimensional analysis. Based on the individual Raman peak patterns, the drug and excipients forming the matrix of the pellets and the film coating were successfully visualized with high spatial resolution, verifying homogeneous drug distribution and intact polymer coating of the pellet. Further, analysis of the pellets after certain time intervals during drug release testing revealed pore formation in the polymer coating facilitating drug release and preceding drug depletion in the pellets matrix. CRM represents an upcoming technique for analytical characterization of carrier systems and elucidation of their complex drug release mechanisms, thus supporting rational development of novel therapeutics. Copyright © 2016 John Wiley & Sons, Ltd.     

Ultrasound-intensified laccase production from Trametes versicolor

An efficient intermittent ultrasonic treatment strategy was developed to improve laccase production from Trametes versicolor mycelia cultures. The optimized strategy consisted of exposing 2-day-old mycelia cultures to 5-min ultrasonic treatments for two times with a 12-h interval at the fixed ultrasonic power and frequency (120 W, 40 kHz). After 5 days of culture, this strategy produced the highest extracellular laccase activity of 588.9 U/L among all treatments tested which was 1.8-fold greater than the control without ultrasound treatment. The ultrasonic treatment resulted in a higher pellet porosity that facilitated the mass transfer of nutrients and metabolites from the pellets to the surrounding liquid. Furthermore, the ultrasonic treatment induced the expression of the laccase gene (lcc), which correlated with a sharp increase in both extracellular and intracellular laccase activity. This is the first study to find positive effects of ultrasound on gene expression in fungal cells. These results provide a basis for understanding the stimulation of metabolite production and process intensification by ultrasonic treatment in filamentous fungal culture.     

A Study of the Fracture of Pellets Fired Against a Target

Pellets of sintered Al₂O₃ of approximately 3 mm diameter and length were broken in the Brazilian mode and the distribution of strength obtained. It was found that there was also a distribution of Young's modulus E. Hertzian theory implies that the maximum impact force of a pellet fired against a rigid target would depend on E. However, since the pellets can strike in different geometries there is a distribution of impact force for a fixed E. Comparison of theory with data obtained with a force-time transducer as the target showed that the major variation of maximum recorded force could be assigned to the variation of E. The median of the maximum recorded force varied with velocity as v^6/5, implying that the pellets behaved approximately as impacting spheres. An attempt was made to predict the probability of breakage in one impact from convoluting the distribution of impact force with the strength distribution from the Brazilian test converted to the equivalent strength distribution expected for impacting spheres. This gave the correct order of magnitude but did not accurately predict the experimental values.     

Centrifugal distortion constants and force field of HClCO

Measurement of the a- and b-type rotational transitions of formyl chloride, HClCO, was extended up to J = 50 and k_a = 5 ← 4 in the frequency range of 8 to 200 GHz. Accurate rotational parameters including the sextic centrifugal distortion constants were determined from the observed spectrum for the ³⁵Cl and ³⁷Cl species. The τ defect in the planarity relations of the quartic centrifugal distortion constants was found to be negligibly small. From the quartic centrifugal distortion constants and the previously reported fundamental vibrational frequencies, force constants of formyl chloride were calculated by assuming the Urey-Bradley force field.     

In vitro contrast-enhanced ultrasound measurements of capillary microcirculation: Comparison between polymer- and phospholipid-shelled microbubbles

The focus of contrast-enhanced ultrasound research has developed beyond visualizing the blood pool and its flow to new areas such as perfusion imaging, drug and gene therapy, and targeted imaging. In this work comparison between the application of polymer- and phospholipid-shelled ultrasound contrast agents (UCAs) for characterization of the capillary microcirculation is reported. All experiments are carried out using a microtube as a vessel phantom. The first set of experiments evaluates the optimal concentration level where backscattered signal from microbubbles depends on concentration linearly. For the polymer-shelled UCAs the optimal concentration level is reached at a value of about 2 × 10⁴ MB/ml, whereas for the phospholipid-shelled UCAs the optimal level is found at about 1 × 10⁵ MB/ml.Despite the fact that the polymer shell occupies 30% of the radius of microbubble, compared to 0.2% of the phospholipid-shelled bubble, approximately 5-fold lower concentration of the polymer UCA is needed for investigation compared to phospholipid-shelled analogues. In the second set of experiments, destruction/replenishment method with varied time intervals ranging from 2 ms to 3 s between destructive and monitoring pulses is employed. The dependence of the peak-to-peak amplitude of backscattered wave versus pulse interval is fitted with an exponential function of the time γ = A(1 − exp(−βt)) where A represents capillary volume and the time constant β represents velocity of the flow. Taking into account that backscattered signal is linearly proportional to the microbubble concentration, for both types of the UCAs it is observed that capillary volume is linearly proportional to the concentration of the microbubbles, but the estimation of the flow velocity is not affected by the change of the concentration. Using the single capillary model, for the phospholipid-shelled UCA a delay of about 0.2-0.3 s in evaluation of the perfusion characteristics is found while polymer-shelled UCA provide response immediately. The latter at the concentration lower than 3.6 × 10⁵ MB/ml have no statistically significant delay (p < 0.01), do not cause any attenuation of the backscattered signal or saturation of the receiving part of the system. In conclusion, these results suggest that the novel polymer-shelled microbubbles have a potential to be used for perfusion evaluation.     

Characterizing the Evolution of Porosity during Controlled Drug Release

Nuclear magnetic resonance (NMR) techniques have been successfully used to characterize the evolving pore structure of partially soluble pharmaceutical pellets as they absorb water and release soluble components. The restricted diffusivity of water trapped within pellets, which have been immersed in water for differing times, has been measured by pulsed field gradient NMR. These measurements have been used to calculate the surface-to-volume ratio and tortuosity of the pore structure. A one-shot Carr–Purcell–Meiboom–Gill sequence has been used to measure the spin–spin (T ₂) relaxation time of water trapped within the pellets. These data have been regularized and then analyzed by the Brownstein–Tarr model to provide a pore size distribution for the pellets as a function of increasing immersion time. It has been found that pore structure changes significantly as water enters the pellet matrix. Two pellet formulations (herein referred to as placebo and drug-loaded) were studied and showed the same trends of a decreasing surface-to-volume ratio and tortuosity with increasing immersion time. At an immersion time of 10 min, both of these parameters decreased to approximately 70% of their values compared to an immersion time of 2 min. The placebo material tested consistently had both a higher tortuosity and surface-to-volume ratio than the drug-loaded material. At an immersion time of 2 min, the tortuosity for the placebo and drug-loaded materials were about 18 and about 10, respectively, and surface-to-volume ratios of about 6 μm⁻¹ and about 5 μm⁻¹, respectively. The materials tested also show changes in their pore size distribution with immersion time. In both formulations the mean and modal pore sizes increase with immersion time. The placebo material maintains an approximately similar mean and modal pore size, about 2 μm over the timescales studied, suggesting a more symmetric pore size distribution. In the drug-loaded pellets the mean pore size is much higher than the modal pore size, their values being 6.5 and 2.1 μm after 10 min immersion time, respectively. Authors' address: Michael D. Mantle, Department of Chemical Engineering, University of Cambridge, Pembroke Street, Cambridge CB2 3RA, UK     

Threshold effects in the interaction of a plasma with injected pellets in the T-10 tokamak

Sharp changes (peaks and dips) of the radiation signal from carbon pellets injected into the plasma in the tokamak are related to the level of introduced disturbances. The threshold size (near 0.3 mm) is determined beginning with which a pellet in the ohmic plasma of the T-10 tokamak initiates tearing processes in a region with q < 2 and Kadomtsev reconnection in the central region with q = 1. A model describing ablation under the conditions of pellet-induced reconnections is proposed. This model satisfactorily describes the observed shape of the ablation rate curve.     

Synchrotron μ‐XRF study on compositional uniformity of uranium–thorium oxide pellets prepared by different processes

A μ‐XRF study to assess the distribution of uranium and thorium in (U,Th)O₂ pellets covering the composition of advanced heavy water reactor (AHWR) fuel pellets prepared by powder metallurgical compaction (PMC) and coated agglomerate pelletization (CAP) routes was made using micro‐focus beam line (BL‐16) of Indus‐2 synchrotron radiation facility. The methodology thus developed was successfully applied to these pellets. The study reveals that the uranium distribution in pellets prepared by PMC route is uniform, whereas the pellets prepared through CAP route have a wide range of compositional variation. In addition, the uniformity in CAP route‐prepared pellets improves with increase in the relative amount of uranium in the pellets. The sample preparation in present methodology is very simple compared with scanning electron microscopy. The study reveals the utility of synchrotron‐based μ‐XRF for fuel pellet characterization of AHWR reactors. Alhough CAP route of fuel pellet preparation requires less exposure of personnel to high radiation dose, the non‐uniformity in the fuel pellet must be considered when using these pellets in reactors. Copyright © 2014 John Wiley & Sons, Ltd.     

Evaluation of effects of ultrasound-assisted saucing on the quality of chicken gizzards

The purpose of this study was to evaluate the effects of ultrasound-assisted saucing on the quality of chicken gizzards. The results showed that with the prolonging of the saucing time, the yield, water holding capacity (WHC), lightness (L*), redness (a*) and springiness of chicken gizzards significantly decreased, while the shear force, hardness and chewiness significantly increased (P < 0.05). When the saucing time was the same, the yield, WHC, springiness and tenderness of the ultrasound group were significantly higher than those of the non-ultrasound group (P < 0.05). In particular, when the saucing time was 30 min, the yield, WHC and springiness of the ultrasound group increased by 2.13%, 0.97% and 10.53%, and the shear force decreased by 21.22% compared with those of the non-ultrasound group, respectively. Besides, ultrasound pretreatment increased the content of aromatic compounds, short-chain alkanes, alcohols, aldehydes and ketones, and the principal component analysis displayed that C-50 (saucing for 50 min without ultrasound pretreatment) and U-30 (saucing for 30 min with ultrasound pretreatment) were similar in flavor. Therefore, ultrasound pretreatment is a potential way to improve the quality of saucing chicken gizzards and shorten the processing time.     

Electron spin resonance characterization of calcretes from Thar desert for dating applications

Results of a study to characterize electron spin resonance (ESR) signals from naturally occurring carbonates from Thar desert are reported. Three radiation induced signals at g=2.0071 (signal A, very weak), g=2.0012 (signal B) and g=2.0003 (signal C) with linewidths ranging from 0.5–2 G are seen. A broad signal (BL) with linewidth 7 G is also seen at 2.0038. Detailed ESR experiments involving (1) sensitivity of ESR signals to ionizing radiation, (2) intensity variation of ESR signals with microwave power at different temperatures, (3) analysis of acid insoluble residue to estimate the interference from ESR signals of silicate fraction, and (4) X-ray diffraction analysis (to study possible phase changes on heating), led to the choice of signal BL for dating. Experiments on acid insoluble residue revealed that signal C has a contribution from the E′₁ centre of quartz and signal B is the parallel component (g_∥) of the E′₁ centre. Paleodose estimates based on signal BL are stratigraphically consistent.     

Structure of luminous clouds near a sublimated hydrogen pellet

The spatial structure of a luminous cloud near a hydrogen pellet sublimated in a tokamak plasma is investigated experimentally. The luminous cloud has the form of a constant-intensity plateau extended along the magnetic field and is surrounded by an exponentially fading halo. The cross size of the plateau is determined by the boundary of the ionization region of atoms leaving the pellet surface. The plateau length is approximately determined by the balance between the pressures in the luminous cloud and the bulk plasma. Taking into account the structure described is important for the correct interpretation of the signals from alpha-particle diagnostics by charge-exchange neutral fluxes, because these signals depend on the characteristic dimensions of the cloud.     

Oxygen hole centers in coesite,a high pressure phase of SiO2

Electron spin resonance (ESR) spectra have been measured for coesite synthesized under high pressure condition from natural quartz and irradiated by γ-rays at 77K. The prominent signals detected at 77 K have an anisotropicg-factor of orthorhombic symmetry,g ₁=2.0015,g ₂=2.0055 andg ₃=2.065 and are ascribed to an oxygen related hole center in coesite. The observed signal atg _‖=2.0033 andg _⊥=2.0085 might be related with an O- or O₂-type hole center.     

Dependence of Cm on the composition of solid binary propellants in ablative laser propulsion

Propulsion pellets of different metal/salt (Zn/CaCO₃) composition have been prepared. The impulse imparted to the pellet by the laser has been measured using two different methods: a torsion pendulum and a piezoelectric sensor. The dependence of the coupling coefficient, C_m, on the composition of the solid binary propellants in ablative laser propulsion has been investigated under different experimental conditions: in vacuum and at atmospheric pressure as well as with two different wavelengths, IR and UV. The composition of the Zn/CaCO₃ propellant mixture that optimizes the coupling coefficient, C_m, has been determined.     

Electron paramagnetic resonance and the thermoluminescence emission mechanism of the 280 °C peak in natural andalusite crystal

Samples of natural andalusite (Al₂SiO₅) crystal have been investigated in terms of thermoluminescence (TL) and electron paramagnetic resonance (EPR) measurements. The TL glow curves of samples previously annealed at 600 °C for 30 min and subsequently gamma-irradiated gave rise to four glow peaks at 150, 210, 280 and 350 °C. The EPR spectra of natural samples heat-treated at 600 °C for 30 min show signals at g=5.94 and 2.014 that do not change after gamma irradiation and thermal treatments. However, it was observed that the appearance of a paramagnetic center at g=1.882 for the samples annealed at 600 °C for 30 min followed gamma irradiation. This line was attributed to Ti³⁺ centers. The EPR signals observed at g=5.94 and 2.014 are due to Fe³⁺. Correlations between EPR and TL results of these crystals show that the EPR line at g=1.882 and the TL peak at 280 °C can be attributed to the same defect center.