Comparison of the determination of a low-concentration active ingredient in pharmaceutical tablets by backscatter and transmission raman spectrometry

A total of 383 tablets of a pharmaceutical product were analyzed by backscatter and transmission Raman spectrometry to determine the concentration of an active pharmaceutical ingredient (API), chlorpheniramine maleate, at the 2% m/m (4 mg) level. As the exact composition of the tablets was unknown, external calibration samples were prepared from chlorpheniramine maleate and microcrystalline cellulose (Avicel) of different particle size. The API peak at 1594 cm(-1) in the second derivative Raman spectra was used to generate linear calibration models. The API concentration predicted using backscatter Raman measurements was relatively insensitive to the particle size of Avicel. With transmission, however, particle size effects were greater and accurate prediction of the API content was only possible when the photon propagation properties of the calibration and sample tablets were matched. Good agreement was obtained with HPLC analysis when matched calibration tablets were used for both modes. When the calibration and sample tablets are not chemically matched, spectral normalization based on calculation of relative intensities cannot be used to reduce the effects of differences in physical properties. The main conclusion is that although better for whole tablet analysis, transmission Raman is more sensitive to differences in the photon propagation properties of the calibration and sample tablets

Sound Production Treatment: Synthesis and Quantification of Outcomes

Treatment for acquired apraxia of speech (AOS) has taken numerous forms, with positive outcomes reported for most treatments. Following a critical evaluation and synthesis of the AOS treatment literature, AOS treatment guideline developers concluded that “taken as a whole, the AOS treatment literature indicates that individuals with AOS may be expected to make improvements in speech production as a result of treatment, even when AOS is chronic….and the strongest evidence for this conclusion exists for treatments designed to improve articulatory kinematic aspects of speech production” (Wambaugh, Duffy, McNeil, Robin, & Rogers, 2006; p.lxii ). This conclusion was based upon general criteria concerning the overall quantity and quality of the evidence-base. Strom (2008) subsequently confirmed the positive effects of articulatory-kinematic AOS treatment approaches using meta-analysis. The AOS guidelines developers grouped treatment studies by general focus (e.g., articulatory-kinematic, rate/rhythm, intersystemic reorganization, and alternative/augmentative); at the time of the guidelines report, no one treatment had a sufficient database to warrant individual consideration (Wambaugh et al., 2006). Over the past decade, additional AOS treatment evidence has accumulated with investigations moving toward comparisons of treatment approaches (Wambaugh, Mauszycki, & Ballard, 2013). Sound Production Treatment (SPT; Wambaugh, Kalinyak-Fliszar, West, & Doyle, 1998) is an articulatory-kinematic AOS treatment that has received relatively systematic study over the past 15 years. There are now sufficient reports of SPT to support its evaluation as a specific approach rather than as part of the general category of articulatory-kinematic approaches. A synthesis and quantification of the effects of SPT is needed to permit comparison to other treatments, to allow evaluation of different applications of SPT, and to facilitate examination of generalization effects of treatment. The purpose of the current investigation was to quantify the effects of SPT in terms of the magnitude of change (i.e., effect size) associated with treatment and follow-up phases of efficacy studies

In situ monitoring of powder blending by non-invasive Raman spectrometry with wide area illumination

A 785 nm diode laser and probe with a 6 mm spot size were used to obtain spectra of stationary powders and powders mixing at 50 rpm in a high shear convective blender. Two methods of assessing the effect of particle characteristics on the Raman sampling depth for microcrystalline cellulose (Avicel), aspirin or sodium nitrate were compared: (i) the information depth, based on the diminishing Raman signal of TiO2 in a reference plate as the depth of powder prior to the plate was increased, and (ii) the depth at which a sample became infinitely thick, based on the depth of powder at which the Raman signal of the compound became constant The particle size, shape, density and/or light absorption capability of the compounds were shown to affect the "information" and "infinitely thick" depths of individual compounds. However, when different sized fractions of aspirin were added to Avicel as the main component, the depth values of aspirin were the same and matched that of the Avicel: 1.7 mm for the "information" depth and 3.5 mm for the "infinitely thick" depth. This latter value was considered to be the minimum Raman sampling depth when monitoring the addition of aspirin to Avicel in the blender. Mixing profiles for aspirin were obtained non-invasively through the glass wall of the vessel and could be used to assess how the aspirin blended into the main component, identify the end point of the mixing process (which varied with the particle size of the aspirin), and determine the concentration of aspirin in real time. The Raman procedure was compared to two other non-invasive monitoring techniques, near infrared (NIR) spectrometry and broadband acoustic emission spectrometry. The features of the mixing profiles generated by the three techniques were similar for addition of aspirin to Avicel. Although Raman was less sensitive than NIR spectrometry, Raman allowed compound specific mixing profiles to be generated by studying the mixing behaviour of an aspirin-aspartame-Avicel mixture

Phonon Dispersion and Relaxation Time in Uranium Dioxide

Phonon dispersion branches are used to obtain an effective relaxation time to calculate thermal conductivity of Uranium Dioxide (UO2). The method presented closely follows that of Deskins’ phonon-phonon interaction that uses a three-phonon process which satisfies momentum and energy conservation. All phonon branches including longitudinal acoustic, transverse acoustic, longitudinal optical and transverse optical are considered in the calculation of the relaxation time. After one phonon is identified, a scan is initiated to test all phonon combinations that will satisfy the conservation equations. When the scan identifies a valid three-phonon combination a relaxation time is calculated for that combination. All the relaxation times from the possible combinations are summed using Mathias’ rule to obtain a total approximate relaxation time for that phonon. Thermal conductivity at equilibrium can be calculated at a specific temperature using the relaxation time approximation of the Boltzmann equation. This approximation uses specific heat, relaxation time, group velocity and the Bose-Einstein distribution. Eventually, the goal of this work is to apply the routine for calculating relaxation time from this work to a Monte Carlo simulation that will treat systems not in equilibrium

Engineering Planktonic and Biofilm Microalgae Systems For Productivity, Power Requirements, Cost, and Scalability

Microalgae cultivation offers dual benefits as an effective wastewater treatment method and a sustainable source of valuable bioproducts, such as biofuels, bioplastics, and feedstocks. This approach supports sustainability by transforming waste into high-value products while minimizing environmental impact. However, scaling microalgae cultivation to industrial levels presents significant challenges, particularly in optimizing harvesting efficiency, reducing mixing and transport costs, and managing large water requirements. This report compares the productivity, scalability, cost, and energy requirements of two primary cultivation systems: planktonic and biofilm. Planktonic systems, such as open raceway ponds (ORPs), excel in light distribution and nutrient uptake due to continuous mixing, promoting high growth rates. In contrast, biofilm systems are more resource-efficient, using less water and energy while maintaining stable multi-species communities that enhance resilience. This review highlights the importance of addressing key scalability challenges and optimizing system designs. Field-scale studies are essential to advance industrial microalgae cultivation, making it a viable solution for both wastewater treatment and renewable resource generation