•Low mass flux about 9 kg/(m2⋅s) in the vertical evaporator tube.•Parallel/counter-flow of heating water with the downward-flow refrigerant.•Boiling heat transfer coefficient in the range from 234 to ...1008 W/(m2⋅K).•Correlation of obtained result with the predicted Nusselt number up to 92 %.
This experimental study analysis the low mass flux of refrigerant R134a, R404A, and R407C in the smooth vertical evaporator tube with an inner diameter of 32 mm. This downward-flow refrigerant with a mass flux of about 9 kg⋅m−2⋅s−1 in the parallel/counter flow of heating water shows suppressed heat transfer by convective boiling and dominant heat transfer by nucleate boiling. This dominant heat transfer by nucleate boiling is dependent on the superheated wall of evaporator tube. The experimentally obtained Nusselt number correlates 92.2 % for R134a, 92.4 % for R404A, and 83.2 % for R407C with the predicted Nusselt number for mass flux over 10 kg⋅m−2⋅s−1. In summary, the untypically low mass flux of refrigerant about 9 kg⋅m−2⋅s−1 is comparable with the current state of knowledge for low mass flux over 10 kg⋅m−2⋅s−1.
Thermal, mechanical and electrical properties and microstructure of the as-cast and cold-rolled AlMnScZr alloys were studied. Samples were isochronally annealed up to 570°C. The electrical ...resistometry and microhardness together with differential scanning calorimetry measurements were compared to microstructure development that was observed by transmission and scanning electron microscopy and also X-ray diffraction. Due to fine, coherent, and uniformly distributed Al3Sc particles, the hardening effect occurred in the studied alloys. The cold rolling at room temperature that was prior to a heat treatment has no substantial effect on temperature range of the Al3Sc-phase precipitation. However, the cold rolling accelerates the precipitation of Mn-containing particles. This precipitation is dependent on deformation degree. The formation of Mn-containing particles is responsible for the intensive resistivity decrease in the cold-rolled materials compared to the as-cast material. The apparent activation energy for precipitation of the Al3Sc and Al6Mn particles in the cold-rolled AlMnScZr alloy was determined as 116±9kJmol−1 and 162±22kJmol−1 respectively.
The aim of this study was to evaluate the correlation between the change in heart strains and the success rate of Cardiac Resynchronization Therapy (CRT) optimization. We further explored the benefit ...of speckle tracking for CRT.
In this prospective cohort study, CRT-Ds were implanted to 60 patients. 3 months later, the response was evaluated. In the non-responders, optimization based on speckle tracking was performed. The AV interval was optimized with respect to the quality of left ventricle filling and the VV interval was optimized with respect to heart strains. After a further three months, the optimization success was evaluated.
Thirty-nine patients responded well to the initial CRT. The response was independent of etiology; the subsequent optimization was however more successful in dilated cardiomyopathy (DCM) (8 out of 9) than in ischemic heart disease (IHD) patients (3 out of 10 responded). The ejection fraction increase and area strain were the best predictors of NYHA improvement.
AV and VV optimization in patients who do not respond well to initial CRT seems to have better results in patients suffering from DCM. Speckle tracking (specifically A-strain) may be used to guide CRT optimization (Tab. 2, Fig. 3, Ref. 22).
In diabetic patients, there is a discrepancy in guidelines for ankle-brachial index (ABI) screening for peripheral arterial disease (PAD). While diabetes organizations suggest the value of upper ...limit of normal ABI to be 1.3, cardiologists recommend 1.4. Also, guidelines recommend using the higher value of ankle pressure (HAP) but multiple recent studies propose the opposite (LAP).
In this prospective study, we performed ABI measurements in 62 diabetic patients. Results were calculated by comparing higher and lower values of ankle pressure to those of duplex ultrasound (stenosis ≥ 50 % was considered PAD). Special attention was paid to patients with high and non-measurable ABI.
LAP ABI appears to be a preferable method for PAD screening in diabetics. The upper cut-off value of 1.4 yielded better results with sensitivity of 93 % and negative predictive value of 91 %. No limbs with ABI between 1.3 and 1.4 with significant stenosis were found. However, using HAP for the upper cut-off captured additional PAD patients. PAD was abundant among patients with high or non-measurable ABI.
LAP should be used for assessing low ABI (cut-off 0.9) while HAP for detecting the abnormally high ABI. The preferable high ABI cut-off is 1.4. Condition with abnormally high or non-measurable ABI should be considered as PAD (Tab. 3, Ref. 22).
In response to the widespread youth mental health crisis, some kindergarten-through-12th-grade (K-12) schools have begun employing artificial intelligence (AI)-based tools to help identify students ...at risk for suicide and self-harm. The adoption of AI and other types of educational technology to partially address student mental health needs has been a natural forward step for many schools during the transition to remote education. However, there is limited understanding about how such programs work, how they are implemented by schools, and how they may benefit or harm students and their families. To assist policymakers, school districts, school leaders, and others in making decisions regarding the use of these tools, the authors address these knowledge gaps by providing a preliminary examination of how AI-based suicide risk monitoring programs are implemented in K-12 schools, how stakeholders perceive the effects that the programs are having on students, and the potential benefits and risks of such tools. Using this analysis, the authors also offer recommendations for school and district leaders; state, federal, and local policymakers; and technology developers to consider as they move forward in maximizing the intended benefits and mitigating the possible risks of AI-based suicide risk monitoring programs.
Basic tenets related to the use of three main classes of potentiometric redistribution fluorescent dyes (carbocyanines, oxonols, and rhodamines) are discussed in detail. They include the ...structure/function relationship, formation of nonfluorescent (H-type) and fluorescent (J-type) dimers and higher aggregates, probe partitioning between membranes and medium and binding to membranes and intracellular components (with attendant changes in absorption and emission spectra, fluorescence quantum yield and lifetime). The crucial importance of suitable probe-to-cell concentration ratio and selection of optimum monitored fluorescence wavelength is illustrated in schematic diagrams and possible artifacts or puzzling results stemming from faulty experimental protocol are pointed out. Special attention is paid to procedures used for probe-response calibration (potential clamping by potassium in the presence of valinomycin, use of gramicidin D in combination with N-methylglucamine, activation of Ca-dependent K-channels by A23187, the null-point technique). Among other problems treated are dye toxicity, interaction with mitochondria and other organelles, and possible effects of intracellular pH and the quantity of cytosolic proteins and/or RNA on probe response. Individual techniques using redistribution dyes (fluorescence measurements in cuvettes, flow cytometry and microfluorimetry of individual cells including fluorescence confocal microscopy) are discussed in terms of reliability, limitations and drawbacks, and selection of suitable probes. Up-to-date examples of application of slow dyes illustrate the broad range of problems in which these probes can be used.
Zusammenfassung
Hintergrund
Zur Bestimmung der therapeutischen Impulsrichtung bei der Atlastherapie nach Arlen gilt die Anfertigung einer a.-p.-Röntgenaufnahme des zervikookzipitalen Übergangs ...traditionell als unverzichtbar. Überlegungen zum Strahlenschutz sowie technische und ökonomische Aspekte förderten die Suche nach einer klinischen Methode, die in der Lage ist, die radiologische Untersuchung zu ersetzen. Zur Diskussion stand der manualdiagnostische 3-Zeichen-Test nach Coenen
Methodik
Die Zuverlässigkeit des 3-Zeichen-Tests wurde an 438 neurologisch gesunden Patienten mit Funktionsstörung der oberen Halswirbelsäule (HWS) untersucht. Das Testergebnis jedes einzelnen Patienten wurde mit der Analyse seiner Atlas-a.-p.-Röntgenaufnahme verglichen. Jeder Patient erhielt die Atlastherapie nach Arlen gemäß dem 3-Zeichen-Test-Ergebnis; die Bestimmung der Sensitivität des Tests erfolgte aus dem Therapieergebnis nach einmaliger Behandlung.
Ergebnisse
Eine Übereinstimmung des 3-Zeichen-Tests mit der Röntgenbildanalyse ergab sich bei 84,6 % der untersuchten Patienten, keine Übereinstimmung fand sich bei 8,5 % und unklar blieben 6,3 %. Eine Bestätigung des Tests durch das Therapieergebnis nach einmaliger Behandlung wurde bei 94,5 % der Patienten ermittelt, bei 5,3 % fand sich keine Bestätigung.
Schlussfolgerung
Bei der Bestimmung der atlastherapeutischen Impulsrichtung erwies sich der 3-Zeichen-Test als mindestens gleichwertig mit der Röntgenbildanalyse. Der Test kann somit die rein therapeutisch indizierte Röntgenuntersuchung des zervikookzipitalen Übergangs ersetzen und leistet einen wichtigen Beitrag zur Minderung der Strahlenexposition. Er ist kein Ersatz für eine diagnostische Röntgenaufnahme zum Ausschluss pathologischer Prozesse an der HWS bei auffälliger Anamnese und suspekter Symptomatik.
HintergrundZur Bestimmung der therapeutischen Impulsrichtung bei der Atlastherapie nach Arlen gilt die Anfertigung einer a.-p.-Röntgenaufnahme des zervikookzipitalen Übergangs traditionell als ...unverzichtbar. Überlegungen zum Strahlenschutz sowie technische und ökonomische Aspekte förderten die Suche nach einer klinischen Methode, die in der Lage ist, die radiologische Untersuchung zu ersetzen. Zur Diskussion stand der manualdiagnostische 3-Zeichen-Test nach CoenenMethodikDie Zuverlässigkeit des 3-Zeichen-Tests wurde an 438 neurologisch gesunden Patienten mit Funktionsstörung der oberen Halswirbelsäule (HWS) untersucht. Das Testergebnis jedes einzelnen Patienten wurde mit der Analyse seiner Atlas-a.-p.-Röntgenaufnahme verglichen. Jeder Patient erhielt die Atlastherapie nach Arlen gemäß dem 3-Zeichen-Test-Ergebnis; die Bestimmung der Sensitivität des Tests erfolgte aus dem Therapieergebnis nach einmaliger Behandlung.ErgebnisseEine Übereinstimmung des 3-Zeichen-Tests mit der Röntgenbildanalyse ergab sich bei 84,6 % der untersuchten Patienten, keine Übereinstimmung fand sich bei 8,5 % und unklar blieben 6,3 %. Eine Bestätigung des Tests durch das Therapieergebnis nach einmaliger Behandlung wurde bei 94,5 % der Patienten ermittelt, bei 5,3 % fand sich keine Bestätigung.SchlussfolgerungBei der Bestimmung der atlastherapeutischen Impulsrichtung erwies sich der 3-Zeichen-Test als mindestens gleichwertig mit der Röntgenbildanalyse. Der Test kann somit die rein therapeutisch indizierte Röntgenuntersuchung des zervikookzipitalen Übergangs ersetzen und leistet einen wichtigen Beitrag zur Minderung der Strahlenexposition. Er ist kein Ersatz für eine diagnostische Röntgenaufnahme zum Ausschluss pathologischer Prozesse an der HWS bei auffälliger Anamnese und suspekter Symptomatik.
Redistribution potentiometric dyes represent a powerful tool for monitoring membrane potential of mitochondria, especially when these dyes are used with flow cytometry. In particular, ...tetramethylrhodamine methyl ester proved to be suitable for the screening of mitochondrial membrane potential in cultured human skin fibroblasts from patients suffering from different defects of oxidative phosphorylation. We have developed a method that makes it possible to measure the changes in mitochondrial membrane potential, or to assess the differences between respective mitochondrial membrane potentials in investigated cells and controls in the absolute scale of millivolts. Our approach employs the fact that a logarithmic transformation of Nernst equation-controlled intensity of fluorescence from potentiometric dyes accumulated in mitochondria leads to a linear scale for mitochondrial membrane potentials.
PDF
