Evaluation of Aloe weloensis (Aloeacea) Mucilages as a Pharmaceutical Suspending Agent

Natural polymers, specifically mucilages, have been used as a suspending agent for a long period of time. Natural excipients can serve as an alternative to synthetic products since they are less expensive, less toxic, and devoid of environmental pollution. There are many species of Aloe found in Ethiopia which can be used as a source of mucilage. In this study, mucilage from Aloe weloensis, which is found in Wollo floristic region, was extracted and tested as a suspending agent at different suspending agent concentrations and compared with standard suspending agents (acacia and sodium carboxy methylcellulose (NaCMC)) by formulating zinc oxide suspension. The mucilage obtained from Aloe weloensis leaves has shown comparable suspending agent ability with acacia. The rate of sedimentation and viscosity was higher at 1% and 4% mucilage concentrations than acacia though the difference was not significant ( p > 0.05 ). The suspension was slightly basic and easily dispersible than NaCMC. Suspensions formulated from NaCMC were superior in terms of viscosity and sedimentation volume which was significantly different ( p < 0.05 ) accompanied by lower flow rates than suspensions formulated from acacia and Aloe weloensis mucilages. The results suggested that Aloe weloensis mucilage could be used as an alternative suspending agent.

Syanovskaya underground quarry (Moscow region)

В Южном Подмосковье до сих пор сохранилось несколько десятков разветвленных подземных заброшенных каменоломен, которые обнаруживают и посещают энтузиасты и которые являются объектами спелеотуризма. Протяженность некоторых из них превышает 3–5 км. В настоящее время эти объекты не являются учтенными месторождениями и расположены, как правило, под деревнями. В статье раскрыты геолого-тектонические, геоморфологические и социально-исторические предпосылки развития подземной камнедобычи в нижнем течении реки Пахра. На основе архивных материалов и преимущественно дореволюционных изданий реконструирована история заложения и развития крупнейших подземных каменоломен Московской области ― Съяновских. Установлено, что добыча в каменоломнях велась с начала XVII по конец XIX века. Описано современное состояние подземных горных выработок. Приведена краткая история туристического освоения Съяновских каменоломен. In the south of the Moscow Region, there are still some dozens of abandoned underground quarries whose forked tunnels still attract enthusiasts and speleo-tourists. Some underground quarries extend over more than 3–5 kilometres. Nowadays, these objects are no longer registered as quarries and are often situated under villages. The article treats geological, tectonic, geomorphological, social and historical prerequisites for the development of underground quarries in the lower flow of the Pakhra River. The author analyzes archival materials and pre-revolutionary publications to reconstruct the history of the Syanovskiye Quarries , the largest underground quarries in the Moscow region. The article maintains that the exploitation of the quarries started in the early 17th century, the quarries were closed in the late 19th centuries. The article describes the present state of the quarries and contains a brief history of tourism-related development of the quarries.

Study on the effect of pore-scale heterogeneity and flow rate during repetitive two-phase fluid flow in microfluidic porous media

Various energy recovery, storage, conversion, and environmental operations may involve repetitive fluid injection and, thus, cyclic drainage-imbibition processes. We conducted an experimental study for which polydimethylsiloxane (PDMS)-based micromodels were fabricated with three different levels of pore-space heterogeneity (coefficient of variation, where COV = 0, 0.25, and 0.5) to represent consolidated and/or partially consolidated sandstones. A total of ten injection-withdrawal cycles were applied to each micromodel at two different flow rates (0.01 and 0.1 mL/min). The experimental results were analyzed in terms of flow morphology, sweep efficiency, residual saturation, the connection of fluids, and the pressure gradient. The pattern of the invasion and displacement of nonwetting fluid converged more readily in the homogeneous model (COV = 0) as the repetitive drainage-imbibition process continued. The overall sweep efficiency converged between 0.4 and 0.6 at all tested flow rates, regardless of different flow rates and COV in this study. In contrast, the effective sweep efficiency was observed to increase with higher COV at the lower flow rate, while that trend became the opposite at the higher flow rate. Similarly, the residual saturation of the nonwetting fluid was largest at COV = 0 for the lower flow rate, but it was the opposite for the higher flow rate case. However, the Minkowski functionals for the boundary length and connectedness of the nonwetting fluid remained quite constant during repetitive fluid flow. Implications of the study results for porous media-compressed air energy storage (PM-CAES) are discussed as a complementary analysis at the end of this manuscript.Supplementary material: Figures S1 and S2 https://doi.org/10.6084/m9.figshare.c.5276814.Thematic collection: This article is part of the Energy Geoscience Series collection available at: https://www.lyellcollection.org/cc/energy-geoscience-series

Assessment of needle tip geometry during infusions into a brain phantom gel

Convection-enhanced delivery (CED) is a promising method to deliver therapeutic drugs directly into the brain that has shown limited efficacy, mainly attributed to backflow, in which the infused drug flows back along the needle track rather than forward into tissue. This study evaluates the effect of sharp and blunt needle tips on backflow length under different flow rates via CED. Infusions were performed in a transparent 0.6% (w/v) brain phantom agarose hydrogel. Backflow length was significantly higher using sharp-tip needles for higher flow rates. No significant differences were observed between tip shapes for lower flow rates. In conclusion, sharp-tip needles present limitations for higher flow rates, which are needed to deliver more drug during shortest times.

Fluctuation of Inducer Recirculation Stemming From Diffuser Stall in Centrifugal Turbomachinery Near Surge Condition

This work investigates the unsteady fluctuation of inducer recirculation stemming from the diffuser stall that occurs near the surge condition. Experiments and unsteady numerical simulation were utilized for the investigation. Inducer recirculation is known to occur near the surge occurrence flow rate, where the flow rate has a positive slope of the performance curve and the recirculation extends to the upstream of the impeller inlet when decreasing the flow rate more. However, few papers have investigated the unsteady phenomenon of the recirculation, even though the surge is what causes it. Clarifying the recirculation phenomenon is essential in terms of expanding the operation range to the lower flow rate for centrifugal turbomachinery. This was our motivation for investigating the unsteady oscillation phenomenon of the inducer recirculation. We investigated a single-stage centrifugal blower with the maximum pressure rise ratio of 1.2 and focused on the flow rates near surge occurrence. The blower was equipped with an open type centrifugal impeller, a vane-less diffuser, and a scroll casing. The blower performance and pressure time-history data were obtained by experiments. Unsteady simulations using large eddy simulation (LES) were conducted to investigate the flow field in the blower for each flow rate. The obtained performance curve showed that the positive slope of the pressure rise at the lower flow rate was due to the impeller stall and that the inducer recirculation extending upstream of the suction pipe near the slope of the curve was flat. LES analysis revealed that this inducer recirculation had two typical fluctuation peaks, one at 20% of the rotation frequency and the other at 95%. We also found that the stall cell at the impeller inlet propagated in the circumferential direction and swirled at almost the same frequency as the impeller rotation. In addition, the fluctuation at the diffuser derived from the diffuser rotating stall propagated to the suction pipe.

Impact of alum pretreatment on biosand filter performance: a commentary on Curry et al. (2020)

In a recent contribution by Curry and colleagues, a field-derived assessment of a reportedly common pretreatment technique to reduce turbidities of biosand filter (BSF) feed water was reported. Their results demonstrated that despite alum pretreatment achieving lower settled turbidity values relative to control filters, such intervention led to significantly lower flow rates in the alum-dosed BSFs. However, their study stopped short of providing a more meaningful interpretation to what may initially seem like a counterintuitive finding, which is presented here.

Part Load Instability and Rotating Stall in a Multistage Low Specific Speed Pump

A new diffuser design is developed for a low specific speed, multistage pump. In this design the diffuser and the de-swirl vanes are integrated into single vanes. This creates diffuser channels that extend from behind the impeller exit through the cross-over, up to the eye of the next stage impeller. Experiments show the occurrence of a saddle type instability in the head curve. At a critical flow rate of close to 50% of the flow rate at Best Efficiency Point (BEP), the head drops by 7% of the head at BEP. In this study Computational Fluid Dynamics (CFD) are used in an effort to understand the underlying flow phenomena. The head curve that is obtained with the transient CFD simulations contains a saddle type instability at a flow rate that is approximately the same as in the experiments, but with a lower magnitude. At flow rates higher than the critical flow rate, the predicted head and power are in very good agreement with the experimental data. At flow rates lower than the critical flow rate, the head and power are slightly over-predicted. An analysis of the pressure distribution in the pump reveals that the head loss at different flow rates in the diffuser shows a discontinuity at the critical flow rate. Since both the impeller head and the head loss in the vaneless gap increase continuously for decreasing flow rate, this is an indication that the cause of the head instability lies in the diffuser. Moreover, a strong increase in the variability of head and power at flow rates below the critical flow suggests that the phenomenon is unsteady. Flow patterns in the impeller and in the diffuser, as calculated by CFD, show a high degree of periodicity and are very similar for flow rates down to the critical flow rate. However, for lower flow rates the flow pattern changes completely. A single rotating stall cell is observed that causes two or three neighboring diffuser channels to stall, leading to a significantly lower flow rate or even a reversed flow. This stall pattern rotates in the direction of impeller rotation at a very low frequency of approximately 3.3% of the impeller rotation frequency.

P585Intra left ventricular hemodynamics assessed using 4D flow MRI in the patient with left ventricular thrombus

Background Early detection of left ventricular mural thrombus (LVT) in patients with reduced ejection fraction (EF) is crucial in prevention of arterial embolism. 3D-cine phase-contrast magnetic resonance imaging (4D flow MRI) can visualize the intra-LV vortex flow in diastole and quantify the maximum flow velocity (Vmax) at the apex. it remains, however, unknown whether 4D flow MRI is useful for detecting LVT. Purpose The purpose of our study is to examine the intra-LV vortex formation and flow velocity in patients with severe LV dysfunction using 4D Flow MRI, and to compare differences in intra-LV flow dynamics between patients with and without LVT. We also examined the diagnostic accuracy to detect LVT by 4D flow MRI. Methods Twenty-nine patients with impaired LV function (LVEF 25.8±7.4%, 62.5±12.3 years old, 24 males, 11 with ischemic cardiomyopathy, 9 with LVT) underwent 4D flow MRI from January 2012 to August 2018 in our institution. Intra-LV vortex size was evaluated as vortex/LV area ratio by streamline imaging (Figure 1). The diagnostic accuracy to predict LVT by vortex size and Vmax at the apex was determined by ROC analysis. Results The vortex was smaller (vortex/LV area ratio; 30.6±7.0% vs. 45.1±9.0%, p<0.05) and Vmax at the apex was lower (0.20±0.04 m/s vs. 0.28±0.09 m/s, p=0.013) in patients with LVT compared to those without LVT. The AUC was 0.789 for Vmax (cut-off value=0.226 m/s, sensitivity=0.889, specificity=0.650) and was 0.900 for vortex/LV area ratio (cut-off value=34.7%, sensitivity=0.889, specificity=0.850). Figure 1 Conclusion The smaller size of intra-LV vortex and the lower flow velocity at the LV apex may have association with LVT formation in patients with reduced EF. 4D flow MRI might be useful to predict LVT formation. Large scale longitudinal study is warranted to evaluate the incidence of LVT in the patients with lower flow velocity. Acknowledgement/Funding None

Blockholders on Boards and CEO Compensation, Turnover and Firm Valuation

We find that the presence of independent directors who are blockholders (IDBs) in firms promotes better CEO contracting and monitoring, and higher firm valuation. Using a panel of about 11,500 firm-years with a unique, hand-collected dataset on IDB-identity and a novel instrument, we find that firms with IDBs have lower excess CEO pay, lower flow and stock of CEO equity incentives, and higher valuations. These effects are substantial and robust. Our findings imply that by making it easier for blockholders to obtain a board seat, proxy access rules or bylaws can benefit shareholders.

Estimación del uso de agua en el lavado de agregados pétreos. Caso de estudio: diseño de mezcla asfáltica. [Water use estimation in the washing process of unbound granular aggregates. Case of study: hot mix asphalt design]

Durante el lavado de agregados pétreos para la ejecución de ensayos en el laboratorio se consumen grandes cantidades de agua. En el presente estudio se estimó, el volumen de agua que se utiliza cuando se realiza el diseño de una mezcla asfáltica. Adicionalmente se evaluó, el efecto de lavar el agregado en diversas cantidades másicas y con dos niveles de velocidad de salida de agua del grifo. Se realizó un análisis de varianza (ANOVA) para verificar si los resultados obtenidos son significativos o estáticamente iguales. Como conclusión general se reporta, que el consumo de agua disminuye significativamente cuando se lavan mayores cantidades de material al mismo tiempo y se emplea para rociar o humedecer las partículas, menores caudales.Palabras clave: agua, consumo de agua en el laboratorio, lavado de agregados pétreos, medio ambiente.AbstractLarge quantities of water are consumed during the washing of granular aggregates in laboratory tests. In this study, the volume of water used when is designed a hot mix asphalt - HMA was estimated. Besides, the effect of washing the aggregate in different quantities of mass and with two levels of water speed flow was evaluated. An analysis of variance (ANOVA) was performed to verify if the results obtained are significant or statically equal. As a general conclusion, it is reported that water consumption decreases significantly when larger amounts of material are washed at the same time and used to wash the particles, lower flow rates.Keywords: water, water consumption in the laboratory, washing of unbound granular aggregates, environment.ResumoDurante a lavagem de agregados para a execução de testes no laboratório, grandes quantidades de água são consumidas. No presente estudo, o volume de água utilizado no projeto de uma mistura asfáltica quente foi estimado. Adicionalmente, o efeito da lavagem do agregado em várias quantidades de massa e com dois níveis de velocidade de saída da água da torneira foi avaliado. Uma análise de variância (ANOVA) foi realizada para verificar se os resultados obtidos são significativos ou estaticamente iguais. Como conclusão geral, é relatado que o consumo de água diminui significativamente quando quantidades maiores de material são lavadas ao mesmo tempo e são usadas para umedecer as partículas, taxas de fluxo menores.Palavras-chave: água, consumo de água no laboratório, lavagem de agregados, meio ambiente