Fast Flow Rate Research Articles

Avoiding High‐Pressure Problem for Modified RNA‐attached Polystyrene Support by Pre‐Swelling Using Toluene in the Oligonucleotide Synthesis

This study describes a method to avoid the high‐pressure problem caused by swelling during the detritylation step in oligonucleotide solid‐phase synthesis using a modified RNA‐attached polystyrene support. The high‐pressure problem originated from the fast flow rate of the reagent and swelling of the solid support was solved by the addition of a pre‐swelling step using toluene before the detritylation step. Through this method, 20‐mer modified RNA/DNA oligonucleotide was synthesized at 3.0 mmol scale without pressure problems with 2′‐methoxy uridine polystyrene support, which has a loading capacity of 354 μmol/g. It was confirmed HPLC purity was improved 1.6% and impurities related to depurination were decreased 0.7% in LC–MS through the application of the pre‐swelling step. This approach has potential additional advantages like shortening detritylation times, hence helping overall cycle time and increasing the support amount in the column which leads to higher throughput.

Hydrogeochemistry of Fluorine in Groundwater in Humid Mountainous Areas: A Case Study at Xingguo County, Southern China

The understanding of F− concentration in groundwater in humid areas is limited although there are lots of research on high-fluoride groundwater in arid areas. In this paper, with controlling factors of F− concentrations in humid areas as the focus, 130 groundwater samples, obtained from four subsystems in Northwest Xingguo County, Jiangxi Province, China, were investigated to demonstrate the controlling factors of F− concentrations in humid areas. According to analytical results, the following hydrogeochemical characteristics of the fluorine in humid mountainous areas were determined: (1) F− concentration is positively correlated with total dissolved solids (TDS), Ca2+, HCO 3 − , and pH; (2) the groundwater features a high flow rate and low TDS; (3) the equilibrium constant of CaF2 is less than its solubility product constant, and the fluorine-bearing minerals in rocks are in a dissolved state; and (4) the dissolved fluoride-bearing minerals constitute the main sources of F− in the groundwater. Fluorine mainly comes from groundwater fluorine-bearing minerals in metamorphic rocks. Moreover, the low F− concentration in the groundwater mainly results from the fast flow rate of groundwater. Fluoride in groundwater has great potential hazards in humid areas.

Simulation and Relationship Strength: Characteristics of Knowledge Flows Among Subjects in a Regional Innovation System

A small-world simulation model of a regional innovation system combining the strength of the intersubject relationship of the regional innovation system with the loosely coupled system is constructed. We use a simulation to observe knowledge flow within the regional innovation system under relationships of varying strength. The results show that when the relationship between the subjects of the regional innovation system reaches a certain strength, the system will exhibit high module independence and high network integrity, forming a loosely coupled system. The knowledge flow in the system exhibits the emergence of a fast flow rate, a high mean value and little variance. When relationship strength is at other levels, the emergence of knowledge cannot be identified.

Effects of Chemical and Geometric Microstructures on the Crystallization of Surface Droplets during Solvent Exchange

In this work, we investigate the crystallization of droplets formed on micropatterned surfaces. By solvent exchange in a microchamber, a ternary solution consisting of a model compound β-alanine, water, and isopropanol was displaced by a flow of isopropanol. In the process, oiling-out droplets formed and crystallized. Our results showed that the shape and size of the crystals on surfaces with chemical micropatterns could be simply mediated by the flow conditions of solvent exchange. More uniform crystals formed on hydrophilic microdomains compared to hydrophobic microdomains or homogeneous surfaces. Varying flow rates or channel heights led to the formation of thin films with microholes, connected networks of crystals, or small diamond-shaped crystals. Physical microstructures (represented by microlenses) on the surface allowed the easy detachment of crystals from the surface. Beyond oiling-out crystallization, we demonstrated that the crystal formation of another solute dissolved in the droplets could be triggered by solvent exchange. The length of crystal fibers after the solvent-exchange process was shorter at a faster flow rate. This study may provide further understanding to effectively obtain the crystallization of surface droplets through the solvent-exchange approach.

Performance of the graphite felt flow-through electrode in hexavalent chromium reduction using a single-pass mode

Flow-through electrodes generally outcompete traditional parallel-plate electrodes in current efficiency and mass transfer. High-performance electrode materials can be costly and complicated to fabricate, hindering their wide application. In this study, we used commercial graphite felt (GF) as the cathode of a flow-through electrochemical cell to investigate its potential in treating Cr(VI) solution through electroreduction. The flow-through design with the porous GF electrode allowed sufficient contact surface with Cr(VI) and single-pass tests demonstrated a high reduction efficiency (95~100%) [117 mg/L~3 mg/L Cr(VI)] under acidic conditions. Slow flow rate and high current promoted electroreduction of Cr(VI). The presence of other metal ions could further improve Cr(VI) reduction at low flow rates due to enhanced conductivity in dilute solutions and generation of low valent ions as reducing agents. At fast flow rates, competition of these ions for reduction decreased Cr(VI) reduction efficiency. Moreover, an acidic environment prevented the coating of an insoluble layer on the GF surface and promoted durable performance, with a lower energy consumption [0.46 kWh for treating 100 L 117 mg/L Cr(VI) solution per unit area of GF]. This work demonstrated the potential of Cr(VI) detoxification using GF cathodes in flow-through electrochemical cell.

Can procedure time for paracentesis be optimized based on bottle selection?

The purpose of our study was to assess if plastic containers could decrease the overall procedure time for paracentesis relative to more commonly used glass containers. In this IRB exempt study, initial pilot data comparing filling time of glass and plastic containers in an ex vivo setting under identical conditions revealed power calculations that n = 37 patients per group would be needed to achieve standard deviation (SD) = 60s, difference (diff) = 40s, two-tailed alpha-level 0.05, and power 80%. Total of 43 patients (93 containers) were enrolled and randomized to glass or plastic bottles at enrollment. Timing of bottle filling was assessed using standardized sonographic screen captures. An interim look at statistics at n = 20 patients indicated that original conjectures from pilot data were conservative and smaller sample size was sufficient to stop the study and conduct the analyses. Specifically, SD = 54s, diff = 49s, two-tailed alpha-level 0.05, and power 80% required n = 21 patients per group. Plastic containers had a statistically significantly lower average filling time per bottle (162.7 ± 53.3s) compared to glass (212.2 ± 50.4s) (p = 0.003). Viscosity was calculated for each specimen and did not affect the statistical significance of the results (p = 0.32). Plastic containers have 50s time savings of per bottle filling time as compared to glass bottles as theorized based on their faster flow rate. This holds true in both an ex vivo setting and in patients and can have important downstream impacts on patient throughput, provider efficiency and system wide cost savings.

Clinical Utility of Central and Peripheral Airway Nitric Oxide in Aging Patients with Stable and Acute Exacerbated Chronic Obstructive Pulmonary Disease.

PurposeExhaled nitric oxide has been used as a marker of airway inflammation. The NO concentration in the central and peripheral airway/alveolar can be measured by a slow and fast exhalation flow rate to evaluate inflammation in different divisions within the respiratory tract. We hypothesized that FeNO200 (exhaled NO at a flow rate of 200mL/s) could be used as an evaluation tool for peripheral airway/alveolar inflammation and corticosteroid therapy in chronic obstructive pulmonary disease (COPD) patients.MethodsWe recruited 171 subjects into the study: 73 healthy controls, 59 stable COPD patients, and 39 acute exacerbations of COPD (AECOPD) patients. Exhaled nitric oxide (FeNO50 (exhaled NO at a flow rate of 50mL/s)), FeNO200 and CaNO (peripheral concentration of NO/alveolar NO) and clinical variables including pulmonary function, COPD Assessment Test (CAT), C-reactive protein concentration (CRP) and circulating eosinophil count were measured among the recruited participants. FeNO50, FeNO200 and CaNO were repeatedly evaluated in 39 AECOPD patients after corticosteroid treatment.ResultsFeNO200 was significantly higher in stable COPD and AECOPD patients than in healthy controls. Nevertheless, CaNO could not differentiate COPD from healthy controls. No correlation was found between circulating eosinophil counts or FEV1 and exhaled nitric oxide (FeNO50, FeNO200, CaNO) in COPD patients. For AECOPD patients, 64% of patients had eosinophil counts >100 cells/µL; 59% of patients had FeNO200 >10 ppb; only 31% of patients had FeNO50 > 25 ppb. Among AECOPD patients, the high FeNO50 and FeNO200 groups’ levels were significantly lower than their baseline levels, and significant improvements in CAT were seen in the two groups after corticosteroid treatment. These implied a good corticosteroid response in AECOPD patients with FeNO200>10ppb.ConclusionFeNO200 is a straightforward and feasible method to evaluate the peripheral NO concentration in COPD. FeNO200 can be a type 2 inflammation biomarker and a useful tool for predicting corticosteroid therapy in COPD.

Rapid and high-capacity loading of IgG monoclonal antibodies by polymer brush and peptides functionalized microspheres

Fast-throughput and cost reduction of current purification platforms are becoming increasing requests during antibody manufacture. The macroporous-matrix absorbents have presented extensive potentiality in improving operational throughput during purification of macromolecule. And meanwhile the peptide ligand has become a promising alternative to recombinant protein ligands for cost reduction of chromatographic purification. Therefore, here we designed a functionalized microspheres resin with both macroporous matrix of polymerized glycidyl methacrylate and ethylene glycol dimethacrylate (PGMA-EDMA) and peptide ligand of hexapeptide (FYEILH). In order to circumvent the steric effect of peptides and amplify the binding sites on macroporous matrix, the peptide ligand was coupled on a liner PGMA polymer brushes grafted on microspheres. Comparing to the conventional agarose-matrix resin and the general peptide-grafted microspheres, the functionalized microspheres presented excellent permeability and high capacity to rapid loading hIgG by maintaining a stable level of dynamic binding capacity at fast flow rate above 110 column volume per hour (cv/h) and very short residence time below 0.5 min. Such functionalized microspheres provide a facile and broadly applicable strategy to develop the attractive candidate for rapid and cost-reduced purification of antibody.

Modeling of a controlled flow cup for improved transitional drinking development in children.

IntroductionClinical observations of children with swallowing disorders using a traditional “sippy” or transitional drinking cup identified a need for a novel cup. Children with swallowing disorders are often unable to initiate the forces required to activate the cup and/or maintain suction pressure. Furthermore, fast flow rates can result in choking.MethodsA new cup design tool is proposed using fluid-cup interactions to capture the changing geometry of the fluid during drinking. A Petri net formulation is integrated with standard fluid flow principles. A new parametric cup simulation provides visualization and direct implementation for microcontroller prototypes. A vent-based controller is developed and modeled for a novel transitional drinking cup design. A simulated pouring study is performed for water and a baseline liquid volume of 200 ml in the cup. The study varies rotation rates, initial volume, system control and desired flow rates.ResultsVolumetric flow rate curves over time are generated and compared in relation to a target flow rate. The simulation results show expected behavior for variations in cup parameters.ConclusionThe new simulation model facilitates future dysphagia research through rapid prototyping by tuning cup geometry, liquid parameters and control signals to meet the varying needs of the users.

Sparged but not stirred: Rapid, ADH-NADH oxidase catalyzed deracemization of alcohols in a bubble column

We investigate in detail both the deracemization reaction rate and maximum conversion of (R,S)-1-phenylethanol in a bubble column and the deactivation rates of both enzymes involved, alcohol dehydrogenase (ADH) and NADH oxidase (nox2). Instead of the predicted ellipsoidal shape of the bubbles, we observe a spherical shape in all our experiments. Calculated values for the area-specific mass transfer coefficient kLa in sparged, but not stirred, solution ranged from 17 to 87 h−1. We find that minimizing the air–liquid interface over time results in the lowest rate of nox2 deactivation. The onset of nox2 dissociation beyond the initial 50 h correlates with a tenfold increase in the observed deactivation rate constant. The highest conversion (99%) for deracemizing 50 mM (R,S)-1-phenylethanol was reached in the shortest reaction time (6 h) if large air bubbles (diameter 2.6 mm) at slow flowrates (5 bubbles/s) were employed. A faster flowrate, which delivers more oxygen per unit time, increased the initial reaction rate but resulted in a slower rate at higher conversions and ultimately incomplete maximum conversion (94%). Reaction rates under sparging were 4–8 times faster than in quiescent solution. Lastly, stirring did not significantly aid conversion (41% vs 37% in quiescent solution after 12 h) but caused increased enzyme deactivation (44 h vs 136 h half-life quiescent solution).

A single centre experience of arteriovenous fistula creation for hemodialysis access in Dar es Salaam, Tanzania

Chronic kidney disease (CKD) is increasingly diagnosed and thus more patients are in need of hemodialysis (HD) to sustain their life. The quality of vascular access for HD should be suitable for repeated puncture and allow a fast blood flow rate for high-efficiency dialysis with minimal complications. Our study aimed to document local experience and early outcomes after arteriovenous fistula (AVF) creation for hemodialysis access including complications related to AVF creation.This was a hospital based clinical audit in which case notes of patients who had undergone AVF creation between May, 2017 and March, 2018 at Muhimbili National Hospital (MNH) were reviewed using a structured data collection tool. Information regarding preoperative assessment for AVF creation, outcome of AVF, and age of the patients were collected. Descriptive statistics were prepared and summarized as tables. A total of 57 case notes of patients who underwent AVF creation for HD access with males contributing majority of patients (77.2%) were reviewed. The predominant age group was 41 to 60 years of age (56.2%) with mean age 47 years and age range of 18 -69 years. Three patients had procedure abandoned on the table due to sclerotic vein. The functional maturation rate was found to be 64.9% and post AVF complications in 15 patients (26.3%). Recorded post AVF creation complications were fistula stenosis/revision (27.8%), bleeding/haematoma (22.2%), limb oedema (22.2%), aneurysm (11.1%), surgical site infection [SSI] (11.1%) and thrombus formation (5.6%).AVF creation for HD access is common at MNH with a functional maturation rate of 64.9%, which is an acceptable rate. The preoperative vascular assessment in this survey was mainly found to be physical examination while preoperative vascular imaging was not commonly done to assess suitability of veins and arteries for AVF creation although post AVF complications are relatively few.

Oiling‐Out Crystallization of Beta‐Alanine on Solid Surfaces Controlled by Solvent Exchange

AbstractIn this work, the solvent‐exchange crystallization processes of beta‐alanine in mixture of isopropanol and water on solid surfaces are reported. As the antisolvent isopropanol displaces the alanine solution pre‐filled in a microchamber, liquid–liquid phase separation occurs at the mixing front. The alanine‐rich subphase forms surface microdroplets that subsequently crystallize with during the solvent exchange. It is found that the flow rates and solid surfaces have significant influence on the droplet size, growth rate, and crystal size and morphology. At fast flow rates, the droplets solidify rapidly, forming spherical‐cap structures resembling the shape of droplets, in contrast to crystal microdomains or thin films formed at slow flow rates. On a highly hydrophilic surface, the crystals form thin film without droplets formation. It is further demonstrated that by the solvent exchange, the crystals, generated by using a stock solution with a very low concentration of the precursor, can be used as seeds to facilitate crystallization in bulk solution. The results suggest that the solvent exchange has the potential to be an effective approach for controlling oiling‐out crystallization, and to be wider applied in, such as, separation and purification of many food, medical, and therapeutic ingredients.

Annual variation characteristics of eutrophication in Dongting Lake, China

The seasonal variation characteristics of eutrophication based on HJ-1 data and synchronous observation data on the ground were studied to provide a theoretical basis for the restoration and management of eutrophication in Dongting Lake. The remote sensing model of chlorophyll-a concentration inversion was established through the comparative analysis of the linear model, exponential model, logarithmic model and quadratic polynomial model by 38 kinds of band combinations. The average relative error was 22.81%. The RMSE of 13.71 mg/m3was far lower than the average concentration of 34.16 mg/m3. The results showed the following. (i) From the perspective of time distribution, the eutrophication degree decreased successively in summer, autumn, spring, and winter. Dongting Lake is mainly in the state of moderate nutrition, which may be attributed to its unique hydrological conditions (short water cycle and fast flow rate). (ii) Eutrophicated water bodies are mainly distributed in the East Dongting Lake and inner lake where the water flow is relatively slow. The water bodies with pool nutrient status are mainly distributed in the outer lake areas where the water flows faster, such as West Dongting Lake.

Three-dimensional simulation of performance in through-mask electrochemical micromachining

Through-mask electrochemical micromachining (TMEMM) is a kind of microfabrication. The major feature of through-mask electrochemical micromachining is that the tool is not limited by the shape, and can be processed in various shapes according to the pattern on the mask. This paper uses the finite element method to create a three-dimensional model to discuss the influence of flow direction, voltage, and electrolyte flow rate on the shape of the through-mask electrochemical micromachining. The simulation results show that processing shape is deeply affected by processing parameters, electrolyte flow rate affects processing temperature distribution, and temperature distribution at the bottom of aperture affects processing depth and flatness during processing, which in turn causes the difference in orifice size and roundness. At the same flow rate, the larger voltage, the larger average radius, flatness, and roundness. At the same voltage, the faster flow rate, the lower average depth, flatness, and average radius. Overall, it has best-processed aperture profile at a flow rate of 0.5 m/s. As a whole, the through-mask electrochemical micromachining is indeed suitable for array microfabrication of various shapes. In this study, experiments were added to verify the simulation results. At a fixed electrolyte flow rate, when the voltage, concentration, and mask aperture are changed, it will have an effect on the overall experimental results. From the experimental results, we know that the electrolyte flow rate and temperature distribution will indeed affect the overall processability.

Monodisperse core–shell silica particles as a high-performance liquid chromatography packing material: Facile in situ silica sol-gel synthesis

In recent years, core–shell silica particles (CSSPs) have been increasingly used for highly efficient separation at fast flow rates and relatively low back pressures in high-performance liquid chromatography (HPLC). However, material synthesis techniques for producing CSSPs economically in batch processes remain elusive. In this report, a practical and straightforward method for the preparation of CSSPs is presented. By refluxing freshly prepared nonporous silica particles in ammonia–water solution in the presence of poly(diallyldimethylammonium chloride) at 70–100 °C, CSSPs with shell thicknesses of up to 300 nm and pore sizes from 8 to 25 nm were easily prepared. The effects of the synthetic conditions on the shell thickness, surface area, and pore size were investigated in detail, and the method reproducibility was evaluated in scale-up experiments. A mechanism of CSSP formation is also proposed. The CSSPs were characterized via scanning electron microscopy, transmission electron microscopy, laser particle size (dynamic light scattering) analysis, and nitrogen adsorption and desorption experiments. The synthesized 3.4-μm CSSPs were functionalized with dimethyloctadecylchlorosilane and used as an HPLC packing material, exhibiting excellent separation performance for both small molecules and large biomolecules. In summary, we report the simplest method developed thus far for the preparation of monodisperse core–shell silica particles suitable for HPLC column packing.

Improving saccharide concentration by mixing octyl acetate during semi-flow, hot-compressed water treatment of woody biomass

Biomass-based ethanol or acetic acid can be produced by fermentation of saccharides following wood hydrolysis. Both high saccharide yield and concentration are essential for achieving an efficient hydrolysis process. However, there can be a trade-off between yield and concentration during semi-flow, hot-compressed water treatment, a candidate for wood hydrolysis. This trade-off is because the fast water flow rate is necessary for high saccharide yields, but the large amount of water dilutes the produced hydrolysate. In this study, we mixed octyl acetate, which is a water-immiscible solvent, during hot-compressed water treatment of beech wood. By adding octyl acetate, a high flow rate was achieved without increasing the water flow rate, and the saccharide concentration was thus improved, while suppressing the decrease in saccharide yield. Furthermore, lignin-derived oligomers, which have inhibitory effects on fermentation, were removed from hydrolysate because they can dissolve in octyl acetate. We performed acetic acid fermentation using the obtained hydrolysate and found that the fermentability was markedly improved compared with the hydrolysate obtained without octyl acetate.

Factors Influencing Mononuclear Cell Collection in Tumor Cell Biotherapy

To investigate the factors affecting counting and collection efficiency of the final product- mononuclear cells (MNCs) in the collection of mononuclear cells for tumor cell biotherapy. The collected data of 142 tumor patients and healthy donors were analyzed, including age, sex, height, weight, BMI, the total blood volume, diagnostic category, vascular access, operator, final product volume, ACD anticoagulant usage, flow rate and circulation times, pre-apheresis Hb, RBC, Plt, WBC, lymphocyte count, monocyte count, neutrophil count, circulating blood volume without anticoagulant, final product MNC and collection efficiency of MNC. CE(collection efficiency)%= final product MNC×100/(pre-apheresis MNC×circulating blood volume without anticoagulant). The factors affecting final products MNC and CE of MNC were detected by T test and multiple linear regression analysis. The CE of tumor patients was higher than that of healthy donors （24.41±1.91,vs 20.01±0.99)，(P=0.043）, and CE of MNC was different among different operators (P=0.01, H=18.59). There was a positive correlation of the final MNC with the volume of final product, ACD anticoagulant usage and pre-apheresis lymphocyte count (P= 0.00, P= 0.01, P= 0.00， r=0.811); CE of MNC negatively correlated with flow rate and pre-apheresis RBC, but positively correlated with operator's working age and ACD anticoagulant usage (P=0.01, P=0.04, P=0.03, P= 0.00, r=0.495). more higher pre-apheresis lymphocyte , more amount of the final product and ACD anticoagulant usage, and more high the final MNC. During the collecting process, more ACD anticoagulant usage and more high operator's seniority, lead to the higher MNC'S CE; while more high pre-apheresis RBC and more fast flow rate, cause the lower the CE of MNC.

Effect of architectural adjustments on pedestrian flow at bottleneck

In the last decades, a series of terrible accidents happened within pedestrian crowds, which makes crowd dynamic a significant issue to be investigated. Literature reviews show that pedestrian flow presents different features within different architectural layout. In this paper, pedestrian movement properties at bottleneck are studied by carrying out series of experiments under laboratory condition. The influence of door sizes and exit locations on pedestrian crowd flow is investigated. It was found that larger door width resulted in shorter evacuation time and faster flow rate. By comparing the fundamental diagram among crowd evacuation, the average velocity increases as the width increases under the same density condition. Interestingly, the influence of the boundary layer, as well as the effective width on pedestrian crowd dynamic, was clearly observed. Our results suggest that the combination of exit width and location resulted in a synergistic effect, but the exit widths gradually became the most important factor influencing the flow rate.

Remediation of Copper Contaminated Soils Using Water Containing Hydrogen Nanobubbles

This basic research study was undertaken to use ecofriendly nanobubbles that can improve the electrokinetic remediation of copper-contaminated soil, as well as to determine that remediation efficiency. The nanobubbles were generated by using pressurized hydrogen gas, and the quantity of hydrogen gas bubble that remained over 14 days was measured. The generated nanobubbles were used as an enhancer to remove a heavy metal on contaminated soil, and their applicability was confirmed. A batch test was used to compare the remediation effects of nanobubbles and distilled water on copper-contaminated soil. The results proved that the nanobubbles are a proper desorption agent for copper-contaminated sand and clay specimens. The solid–liquid ratio and the contact time for desorption of the sand and clay were then respectively determined. A large amount of effluent was obtained from electrokinetic remediation of the sand sample after applying the nanobubbles as an enhancer. The remediation efficiency demonstrated with sand proved to be higher than that for clay. This greater efficiency was attributed to a wider specific surface area, demonstrating the potential use of the nanobubbles as an enhancer for soil contaminated by copper with a large amount of effluent outflow. It was also assumed to be affected by the moving capability of the nanobubbles in the soil layer. Thus, the nanobubbled water can be used to improve the removal of heavy metals from contaminated soils. An ecofriendly enhancer for electrokinetic remediation with a relatively large void ratio and fast flowrate was confirmed by the nanobubbles.

New EMPIR project – Metrology for Drug Delivery

This document presents the scientific and technical objectives, state of the art and expected progress beyond it, and most importantly the expected impact on metrology, science, standards, and society of the new joint research project - MeDD II, Metrology for Drug Delivery (follow up of project MeDD I). It was selected for funding through the EURAMET EMPIR program of the European Commission and the participating countries. The project started in June 2019 and will last for three years. It involves 15 partners from National and Designated Metrology Institutes, companies, and academia. The main objective is to enable traceable measurements of volume, flow and pressure of existing drug delivery devices (like infusion pumps and analysers) and inline sensors that work at flow rates lower than 100 nL/min, in order to prevent inaccurate measurement results. This project will also investigate fast changing flow rates, liquid mixing behaviour and occlusion phenomena in multi-infusion systems with the purpose of improving dosing accuracy in each infusion line.