Measuring Nd(III) Solution Concentration in the Presence of Interfering Er(III) and Cu(II) Ions: A Partial Least Squares Analysis of Ultraviolet-Visible Spectra

Optical spectroscopy is a powerful characterization tool with applications ranging from fundamental studies to real-time process monitoring. However, it can be difficult to apply to complex samples that contain interfering analytes which are common in processing streams. Multivariate (chemometric) analysis has been examined for providing selectivity and accuracy to the analysis of optical spectra and expanding its potential applications. Here we will discuss chemometric modeling with an in-depth comparison to more simplistic analysis approaches and outline how chemometric modeling works while exploring the limits on modeling accuracy. Understanding the limitations of the chemometric model can provide better analytical assessment regarding the accuracy and precision of the analytical result. This will be explored in the context of UV-Vis absorbance of neodymium (Nd³⁺) in the presence of interferents, erbium (Er³⁺) and copper (Cu²⁺) under conditions simulating the liquid-liquid extraction approach used to recycle plutonium (Pu) and uranium (U) in used nuclear fuel worldwide. The selected chemometric model, partial least squares regression, accurately quantifies Nd³⁺ with a low percentage error in the presence of interfering analytes and even under conditions that the training set does not describe.

Using localized Twitter activity to assess harmful algal bloom impacts of Karenia brevis in Florida, USA

Red tide blooms of the dinoflagellate Karenia brevis (K. brevis) produce toxic coastal conditions that can impact marine organisms and human health, while also affecting local economies. During the extreme Florida red tide event of 2017-2019, residents and visitors turned to social media platforms to both receive disaster-related information and communicate their own sentiments and experiences. This was the first major red tide event since the ubiquitous use of social media, thus providing unique crowd-sourced reporting of red tide impacts. We evaluated the spatial and temporal accuracy of red tide topic activity on Twitter, taking tweet sentiments and user types (e.g. media, citizens) into consideration, and compared tweet activity with reported red tide conditions, such as K. brevis cell counts, levels of dead fish and respiratory irritation on local beaches. The analysis was done on multiple levels with respect to both locality (e.g., entire Gulf coast, county-level, city-level, zip code tabulation areas) and temporal frequencies (e.g. daily, every three days, weekly), resulting in strong correlations between local per-capita Twitter activity and the actual red tide conditions observed in the area. Moreover, an association was observed between proximity to the affected coastal areas and per-capita counts for relevant tweets. Results show that Twitter presents a trustworthy reflection of the red tide's local impacts and development over time, and can potentially augment the already existing tools for efficient assessment and a more coordinated response to the disaster.

Quantification of Raman-Interfering Polyoxoanions for Process Analysis: Comparison of Different Chemometric Models and a Demonstration on Real Hanford Waste

The Hanford site represents a complicated environmental remediation challenge, remaining from the production of nuclear weapons. Over 100 million gallons of liquid radioactive waste of unknown composition will be chemically processed and vitrified, but the varying chemical composition and highly radioactive nature of the waste preclude the implementation of more developed, offline technologies to determine the composition. The only practical approach to waste treatment will require the significant utilization of real-time, chemometric modeling approaches. Although chemometric approaches have been applied to the analysis of Hanford waste, the models developed were highly tank-specialized, and limited discussion was provided on how models fared with interfering signals. As the tank waste is largely composed of oxoanions, which tend to have interfering Raman spectra, the general question was posed as to what chemometric approach is best suited to accurately quantify analytes in the presence of interfering signals. This was carried out by examining the ability of classical least square (CLS), principal component regression (PCR), partial least square (PLS), and locally weighted regression (LWR) to quantify NO₃^- and CO₃^2- using their bands around 1050 cm^-1. For all samples, the PLS-based model was found to be the most efficient approach from a model building and application perspective.

Extraction of the trivalent transplutonium actinides americium through einsteinium by the sulfur donor Cyanex 301

When extracting metals with the sulfur donor ligand, Cyanex 301 (bis(2,4,4-trimethylpentyl)dithiophosphinic acid), a transition in the coordination mode of extracted complexes has been observed between Eu and Gd, but not within the actinide series.

Assessment of accuracy of daily set-ups in prostate radiotherapy using electronic imaging

The purpose of the study was to assess the accuracy, using electronic portal imaging, of daily set-ups, in patients undergoing radiotherapy for prostate carcinoma. We used a scanning liquid ion chamber to assess the accuracy of set-ups in 25 consecutive patients undergoing a 6 1/2 week course of radiotherapy to the prostate. Electronic images (EPIs) were collected during 33 treatments to each of four ports. The positions of anatomical structures on the EPIs were compared with the same structures seen on digitally reconstructed radiographs (DRRs) made after CT simulation before beginning radiotherapy. Displacements of the EPIs compared with the DRRs were computer-calculated in millimetres in lateral, longitudinal and rotational directions for each port. 11 patients had ports moved because of discrepancies between the EPIs and the DRRs; eight required moves in the first five treatments to correct systematic (simulator) errors. In the right-left and anterior-posterior directions, nearly 95% of the EPIs were within 5 mm of the simulated port position. In the superior-inferior direction, 98% of the ports were within 5 mm of the simulated port position. Two patients had in-plane rotational errors on the lateral ports (8 degrees and 10 degrees respectively). It was concluded that daily electronic imaging is an effective technique for assessing the accuracy of set-ups in prostate radiotherapy.

Negative regulation of two hyperproliferative keratinocyte differentiation markers by a retinoic acid receptor-specific retinoid: insight into the mechanism of retinoid action in psoriasis

Retinoids down-regulate the expression of metalloproteinases, cytokines, and other genes involved in cell proliferation and inflammation. Tazarotene (AGN 190168), a retinoic acid receptor (RAR)-specific retinoid, is effective in the treatment of psoriasis, a hyperproliferative and inflammatory skin disease. Because negative regulation of genes appears to be important in the antiproliferative and antiinflammatory action of retinoids, we studied the down-regulation of genes in skin raft cultures by this antipsoriatic retinoid. By subtraction hybridization, we found that migration inhibitory factor-related protein (MRP-8) and skin-derived anti-leukoproteinase (SKALP) are down-regulated by AGN 190168. MRP-8 and SKALP are overexpressed in psoriatic lesions as compared to the normal epidermis, and they are markers of hyperproliferative keratinocyte differentiation. We also show that MRP-8 expression is retinoid inhibitable in cultured keratinocytes induced to differentiate with 10% serum or IFN-gamma, and that MRP-8 is inhibited by RAR but not by retinoid X receptor-specific retinoids in a dose-dependent manner. Finally, MRP-8, SKALP, and the previously characterized differentiation marker, transglutaminase I, are all down-regulated in vivo in psoriatic lesions after treatment with AGN 190168 in comparison to placebo. Taken together, these data suggest that these markers may be down-regulated by tazarotene in psoriasis through direct action on keratinocyte gene expression rather than by an overall tazarotene effect on lesional therapeutic status.

GTPase-activating protein interactions with the viral and cellular Src kinases

GTPase-activating protein (GAP), which regulates the activities of Ras proteins, is implicated in mitogenic signal transduction by growth-factor receptors and oncoproteins with tyrosine kinase activity. Oncogenic viral Src (p60v-src) encoded in Rous sarcoma virus possesses elevated tyrosine kinase activity compared with its nononcogenic normal homolog, cellular Src (p60c-src). To examine molecular interactions between GAP and the two Src kinases, immunoprecipitates of Src or GAP prepared from cell lystates were resolved by gel electrophoresis and analyzed by an immunoblot procedure with antibodies to GAP or Src used as probes. Results suggest that p60c-src is associated with a complex containing GAP in immunoprecipitates from lysates of normal rat and chicken cells. However, GAP is not phosphorylated in p60c-src immunoprecipitates subjected to in vitro kinase reactions. By contrast, GAP undergoes tyrosyl phosphorylation in vitro when immunoprecipitates of p60v-src prepared from transformed cell lysates are incubated with ATP. Our findings suggest that p60v-src and p60c-src associate with complexes containing GAP and provide a biochemical link between both kinases and GAP/Ras signal transduction pathways. These results are consistent with the hypothesis that GAP has a role in mediating normal functions of p60c-src as well as oncogenic activities of p60v-src.

Bladder and rectal complications following radiotherapy for cervix cancer

One-hundred and thirty-two patients with cervix carcinoma who were treated with whole pelvis irradiation and two intracavitary applications had bladder and rectal dosimetry during brachytherapy with contrast agents placed into the bladder and rectum prior to orthogonal simulator radiographs. Doses were computer calculated at points A and B, F (bladder), R1 (rectum), and R2 (rectosigmoid). Late occurring bladder and rectal complications were graded on a severity scale of 1 to 3, and 14% had grade 2 or 3 injuries (9% developed fistulas). Statistical evaluation of the data showed that severe bladder and rectal injuries occur more commonly in stage IIIA and IIIB disease and in those receiving high external beam doses (5000 rad +). Analysis of variance tests revealed a significant correlation of brachytherapy dose to points R1 and R2 with severe rectal injuries but there was not a correlation of dose to F with bladder injuries. Nor was there correlation of injuries with dose to point A or the milligram-hour dose. We conclude that our technique for rectal dosimetry is adequate but that an improved technique of bladder dosimetry is needed. Also, when combining whole pelvis irradiation with two intracavitary applications (4000 rad to point A), the whole pelvis dose should probably not exceed 4000-4500 rad.

Citrus artifact interference in aflatoxin M1 determination in milk

Dried citrus waste was fed to dairy cows, their milk was extracted, and aflatoxin M1 was quantitated by using both high pressure liquid chromatography (HPLC) and thin layer chromatography (TLC). Results indicate that a compound from the citrus waste, which is excreted into the milk, interferes with the HPLC determination of aflatoxin M1 in milk and causes a false positive test. This interference can be overcome by using TLC with proper selection of developing solvents.