Deposit formation from evaporating urea-water droplets on substrates of different wettability.

HYPOTHESIS: During the evaporation of urea water solution (UWS), the wall temperature and surface properties influence the dynamics of deposit formation by affecting the internal mass transport. These effects are expected to be reflected in the resulting deposit morphology and allow different deposit regimes to be distinguished. EXPERIMENTS: The temperature of metallic substrates is varied for three different surface treatments to analyze the wetting, evaporation behavior and the crystallization process of single UWS droplets in situ using a high-speed camera. The deposit morphology is captured by confocal microscopy and analyzed via the power spectral density method (PSD). PSD is used to extract the height of different surface features for each deposit, providing valuable information about the local crystallization history. FINDINGS: A significant influence of the surface properties on the crystallization process as well as on the morphology of the final deposit is found. The influence of wettability is described by the resulting internal mass transport, which determine the urea distribution. PSD analysis quantified distinct trends in the scaling tendencies of the deposit aggregates under different wall conditions. The local crystal growth history extracted by PSD agrees well with proposed crystallization mechanisms, which is further supported by high-speed and SEM imaging.

A Statistical Approach for Assessing the Compliance of Integrated Continuous Glucose Monitoring Systems with Food and Drug Administration Accuracy Requirements.

To assess the compliance of "integrated" continuous glucose monitoring (CGM) systems with U.S. Food and Drug Administration requirements, the calculation of confidence intervals (CIs) on agreement rates (ARs), that is, the percentage of CGM measurements lying within a certain deviation of a comparator method, is stipulated. However, despite the existence of numerous approaches that could yield different results, a specific procedure for calculating CIs is not described anywhere. This report, therefore, proposes a suitable statistical procedure to allow transparency and comparability between CGM systems. Three existing methods were applied to six data sets from different CGM performance studies. The results indicate that a bootstrap-based method that accounts for the clustered structure of CGM data is reliable and robust. We thus recommend its use for the estimation of CIs of ARs. A software implementation of the proposed method is freely available (https://github.com/IfDTUlm/CGM_Performance_Assessment).

Continuous Glucose Deviation Interval and Variability Analysis (CG-DIVA): A Novel Approach for the Statistical Accuracy Assessment of Continuous Glucose Monitoring Systems.

BACKGROUND: The accuracy of continuous glucose monitoring (CGM) systems is crucial for the management of glucose levels in individuals with diabetes mellitus. However, the discussion of CGM accuracy is challenged by an abundance of parameters and assessment methods. The aim of this article is to introduce the Continuous Glucose Deviation Interval and Variability Analysis (CG-DIVA), a new approach for a comprehensive characterization of CGM point accuracy which is based on the U.S. Food and Drug Administration requirements for "integrated" CGM systems. METHODS: The statistical concept of tolerance intervals and data from two approved CGM systems was used to illustrate the CG-DIVA. RESULTS: The CG-DIVA characterizes the expected range of deviations of the CGM system from a comparison method in different glucose concentration ranges and the variability of accuracy within and between sensors. The results of the CG-DIVA are visualized in an intuitive and straightforward graphical presentation. Compared with conventional accuracy characterizations, the CG-DIVA infers the expected accuracy of a CGM system and highlights important differences between CGM systems. Furthermore, it provides information on the incidence of large errors which are of particular clinical relevance. A software implementation of the CG-DIVA is freely available (https://github.com/IfDTUlm/CGM_Performance_Assessment). CONCLUSIONS: We argue that the CG-DIVA can simplify the discussion and comparison of CGM accuracy and could replace the high number of conventional approaches. Future adaptations of the approach could thus become a putative standard for the accuracy characterization of CGM systems and serve as the basis for the definition of future CGM performance requirements.

Disordered Eating and Eating Disorders in Adolescent Athletes.

CONTEXT: To summarize available literature to date and discuss the importance of Disordered Eating (DE) in adolescent athletes, with special attention to the female athlete triad. In this paper, the authors will review the literature regarding adolescent athletes who intentionally engage in abnormal eating behaviors and focus on adolescent athletes of all training levels who may be affected by both DE and eating disorders (ED). METHODS: In 2019, the authors completed a systematic literature search on PubMed using the search term variations of "Feeding and Eating Disorders" and "athletes" with "high school." RESULTS: A total of 20 pertinent articles were identified concerning DE in adolescent athletes. ED have been shown to impose higher rates of comorbidity than other psychological disorders and only a small number of individuals with ED seek treatment. ED tend to be more prevalent in adolescent elite athletes than non-athletes of both genders in all sports and levels of competition. CONCLUSIONS: More rigorous tools for family practice physicians, nurses, and coaches to use when working with at-risk adolescent athletes are needed to identify DE behaviors. Healthcare and school professionals need to be educated and trained to detect DE and the components of the female athlete triad. Additional research with adolescent males or those associating with alternative gender roles is also required to help them prevent physical and mental health consequences associated with DE.

Insights into the interplay of wetting and transport in mesoporous silica films.

The understanding and design of wetting-transport and wetting-charge-transport interplay in nanometer-sized pores is a still not fully understood key step in improving nanopore transport-related applications. A control of mesopore wettability accompanied by pore filling and ionic mesopore accessibility analysis is expected to deliver major insights into this interplay of nanoscale pore wetting and transport. For a systematic understanding, we demonstrate a gradual adjustment of nanopore ionic accessibility by gradually tuning silica nanopore wettability using chemical vapor phase deposition of 1H,1H,2H,2H-perfluorooctyl dimethylchlorosilane. The mutual influence of wetting on liquid imbibition, condensation, and molecular transport as well as on heat transfer were studied by ellipsometry, cyclic voltammetry and boiling experiments, respectively. A multi-methodical analytic approach was used to directly couple wetting properties of mesoporous silica thin films to ionic mesopore accessibility allowing us to determine two different ion transport mechanisms based on three defined wetting regimes as well as a threshold hydrophobicity suppressing pore accessibility. Furthermore, boiling experiments showed a clear increase in nucleation site density upon changing the wettability of the mesoporous surfaces from hydrophilic to hydrophobic. Hence, these results provide insights into the complex interplay of pore wall functionalization, wetting, and charge-dependent nanopore properties.

Solid-Liquid Interface Thermal Resistance Affects the Evaporation Rate of Droplets from a Surface: A Study of Perfluorohexane on Chromium Using Molecular Dynamics and Continuum Theory.

We study the role of solid-liquid interface thermal resistance (Kapitza resistance) on the evaporation rate of droplets on a heated surface by using a multiscale combination of molecular dynamics (MD) simulations and analytical continuum theory. We parametrize the nonbonded interaction potential between perfluorohexane (C6F14) and a face-centered-cubic solid surface to reproduce the experimental wetting behavior of C6F14 on black chromium through the solid-liquid work of adhesion (quantity directly related to the wetting angle). The thermal conductances between C6F14 and (100) and (111) solid substrates are evaluated by a nonequilibrium molecular dynamics approach for a liquid pressure lower than 2 MPa. Finally, we examine the influence of the Kapitza resistance on evaporation of droplets in the vicinity of a three-phase contact line with continuum theory, where the thermal resistance of liquid layer is comparable with the Kapitza resistance. We determine the thermodynamic conditions under which the Kapitza resistance plays an important role in correctly predicting the evaporation heat flux.

Assessing System Accuracy of Blood Glucose Monitoring Systems Using Rectangle Target Plots.

BACKGROUND: Results from accuracy assessments of systems for self-monitoring of blood glucose (SMBG) are often visualized in difference or regression plots. These approaches become more difficult to read as the number of data points displayed increases, thus limiting their use. In the recently presented rectangle target plot (RTP) approach, data from each reagent system lot or product are displayed graphically as a single rectangle, thus allowing the plot to remain comprehensible even when displaying system accuracy data from multiple reagent system lots or products. METHODS: The RTP illustrates the accuracy of SMBG systems. Each rectangle shows the mean bias and the variability of a system. By use of statistical tolerance intervals, each rectangle most closely approximates the total error for lower (<100 mg/dL) and upper (≥100 mg/dL) glucose concentrations. RTPs were created for data from 8 different manufacturers of systems for SMBG. In total, the accuracy data of 87 different reagent system lots of 50 different SMBG systems were displayed in RTPs. RESULTS: The RTP approach was suitable for 81 of the 87 reagent system lots analyzed. In the remaining cases, outliers caused excessive skewness of the distribution of measurements. The reagent system lots analyzed were grouped according to manufacturer in RTPs. Data from 3 to 15 different reagent system lots were displayed in each RTP. CONCLUSION: Applying the RTP approach to a large number of reagent system lots showed that it was suitable in more than 93% of cases analyzed. The display of system accuracy data in RTPs enables lot-to-lot variability within specific products and product reliability of specific manufacturers to be visualized in a comprehensible manner.

The Rectangle Target Plot: A New Approach to the Graphical Presentation of Accuracy of Systems for Self-Monitoring of Blood Glucose.

BACKGROUND: The measurement accuracy of systems for self-monitoring of blood glucose (SMBG) is usually analyzed by a method comparison in which the analysis results are displayed using difference plots or similar graphs. However, such plots become difficult to comprehend as the number of data points displayed increases. This article introduces a new approach, the rectangle target plot (RTP), which aims to provide a simplified and comprehensible visualization of accuracy data. METHODS: The RTP is based on ISO 15197 accuracy evaluations of SMBG systems. Two-sided tolerance intervals for normally distributed data are calculated for absolute and relative differences at glucose concentrations <100 mg/dL and ≥100 mg/dL. These tolerance intervals provide an estimator of where a 90% proportion of results is found with a confidence level of 95%. RESULTS: Plotting these tolerance intervals generates a rectangle whose center indicates the systematic measurement difference of the investigated system relative to the comparison method. The size of the rectangle depends on the measurement variability. CONCLUSIONS: The RTP provides a means of displaying measurement accuracy data in a simple and comprehensible manner. The visualization is simplified by reducing the displayed information from typically 200 data points to just 1 rectangle. Furthermore, this allows data for several systems or several lots from 1 system to be displayed clearly and concisely in a single graph.

TNF-α -308 genotypes are associated with TNF-α and TGF-ß1 mRNA expression in blood leucocytes of humans.

AIM: Tumor necrosis factor α (TNF-α) influences the pathogenesis of lung-fibrosis and carcinogenesis in normal cells. Polymorphisms of this gene are suggested to be associated with susceptibility to lung-diseases. Additionally TNF-α is postulated to play a significant role in regulating. Transforming growth factor (TGF-ß1) expression Therefore we investigated if the TNF-α or TGF-ß1 gene expression level is different within the -308 TNF-α genotypes. METHODS: Quantitative Real-time PCR of TNF-α and TGF-ß1 was performed in 178 Germans. Calculations of expression were made with the 2(-ΔΔCT) method. Detection of the -308 promoter polymorphism of the TNF-α gene was performed by rapid capillary PCR with melting curve analysis. RESULTS: The relative TNF-α mRNA expression revealed significant differences between the TNF-α -308 homozygote wild-type G/G (0.00079±0.00011; n=113) and the heterozygote genotype G/A (0.0005±0.00008; n=52; p=0.030) as well as between homozygote wild-type G/G and the homozygote mutant A/A (0.00029±0.00009; n=5; p=0.004). The relative TGF-ß mRNA expression showed, similar to TNF-α, the highest mRNA expression was seen within the TNF-α -308 homozygote wild-types, while the lowest mRNA expression lay within the homozygote mutant-types. CONCLUSION: Our findings suggest that the G-allele of TNF-α -308 is associated with a significantly higher TNF-α mRNA expression compared to the A-allele and that this also reflects in TGF-ß expression. Therefore we support the thesis that TGF-ß is regulated by TNF-α.

TNF-α mRNA expression correlates with TGF-ß mRNA expression in vivo.

TNF-α is postulated to play a significant role in regulating TGF-ß(1) expression. In lung fibroblasts, for example, TNF-α is supposed to induce TGF-ß(1) via AP-1 activation. TNF-α receptor, knock-out mice are resistant to induced fibrosis and over-expression of TNF-α causes increased TGF-ß(1) production in mice. Therefore, we investigated whether TNF-α mRNA levels are associated with the TGF-ß(1) mRNA levels of blood leucocytes in humans. Quantitative real-time PCR of TNF-α and TGF-ß(1) was performed in 118 Germans. Calculations of expression were made with the 2(-ΔΔCT) method. When the investigated population was divided in two groups (TNF-α low and TNF-α high) by the median of the determined TNF-α expression, highly significant (p < 0.0001) differences of TGF-ß1 mRNA expression were revealed. Additionally, dividing the investigated population into quartiles of the determined TNF-α expression showed significantly different TGF-ß1 mRNA expressions. Comparing the determined CT-values of TNF-α in context with these of TGF-ß1, a coefficient of determination R(2) = 0.4635 was calculated. In this study we demonstrated in vivo a significant association of the relative TNF-α/B2M mRNA expression and the relative TGF-ß(1)/B2M mRNA expression in 118 Germans.

Dynamics of the cavity and the surface film for impingements of single drops on liquid films of various thicknesses.

This paper presents experimental and numerical investigations of single drop impacts onto liquid films of finite thickness. The dynamics of the drop impingement on liquid surface films, the shape of the cavity, the surface film dynamics and the residual film thickness are investigated and analysed. The shape of the penetrating cavity within the surface film is observed experimentally using a high-speed video system. Additionally, the thickness of the liquid film between the expanding, receding and retracting cavity and the solid wall is monitored in time using an optical sensor based on chromatic confocal imaging. The effects of various influencing parameters, such as the drop impingement velocity, liquid properties (surface tension and viscosity) and the initial liquid film thickness, on the time evolution of the cavity and film dynamics are investigated. Complementary to the experiments direct numerical simulations of the drop impacts and cavity expansion are performed using a volume-of-fluid free-surface capturing model in the framework of the finite volume numerical method. The numerical predictions of the film thickness dynamics agree well with the experiments for most phases of the impingement process. Finally, a scaling analysis of the residual film thickness between the cavity and the solid wall is performed for various impingement parameters.

Static and dynamic contact angles of evaporating liquids on heated surfaces.

We studied both static and dynamic values of the apparent contact angle for gravity-driven flow of a volatile liquid down a heated inclined plane. The apparent contact line is modeled as the transition region between the macroscopic film and ultra-thin adsorbed film dominated by disjoining pressure effects. Four commonly used disjoining pressure models are investigated. The static contact angle is shown to increase with heater temperature, in qualitative agreement with experimental observations. The angle is less sensitive to the details of the disjoining pressure curves than in the isothermal regime. A generalization of the classical Frumkin-Derjaguin theory is proposed to explain this observation. The dynamic contact angle follows the Tanner's law remarkably well over a range of evaporation conditions. However, deviations from the predictions based on the Tanner's law are found when interface shape changes rapidly in response to rapid changes of the heater temperature. The Marangoni stresses are shown to result in increase of the values of apparent contact angles.

Breakup and atomization of a stretching crown.

This study is devoted to experimental and theoretical investigation of splash produced by spray impact onto a smooth, rigid target under microgravity conditions. In particular, the formation of a film by the deposited liquid, the propagation and breakup of uprising sheets created by drop impacts, and the creation of secondary droplets have been observed. Three scenarios of splash have been identified during the experiments: (i) cusp formation and jetting due to the rim transverse instability, (ii) sheet destruction and the consequent rapid axisymmetric capillary breakup of a free rim, and (iii) the rim merging. Experimental data for various geometrical parameters of splash have been collected. Next, in order to predict the typical length scales of the interjet distance, a linear stability analysis of the rim in relation to transverse disturbances has been performed. The influence of the sheet stretching has been investigated and shown to be significant. The experimentally measured average values of the interjet distances agree well with the theoretical predictions. The sheet stretching is responsible for the appearance of the relatively long interjet distances.

The SCGM1 System: subcutaneous continuous glucose monitoring based on microdialysis technique.

The SCGM1 System is designed to allow continuous glucose monitoring in the subcutaneous interstitial fluid for up to 120 h. The system is based on the microdialysis technique and is composed of three components: (1) a disposable Cassette, which contains the microdialysis catheter (with the necessary tubes), an electrochemical flow-through sensor for glucose measurement, and the fluid reservoirs for both the microdialysis perfusate and a reagent solution containing glucose oxidase; (2) the Sensor Unit, which houses the Cassette and is worn by the patient using a belt pack; and (3) the Data Manager, with an integrated blood glucose meter for the calibration of the glucose signal. The Data Manager also has the option of displaying the continuous glucose signal. The Sensor Unit and Data Manager exchange glucose data and calibration data by radio transmission. In vitro precision was assessed by measurements of two standard glucose solutions (90 mg/dL, 3.4%; 360 mg/dL, 2.4%) over a time course of 4 days. The mean difference (+/- SD) between SCGM1 System devices (n = 11) and 15 glucose standard solutions with different concentrations was 1.4 +/- 3.5 mg/dL. The mean relative difference and the mean absolute relative difference ranged from - 0.6% to 3.7% and from 0.2% to 3.8%, respectively. The inherent physical lag time was 31 +/- 2 min (n = 10). The interference on the glucose signal of ascorbic acid, acetaminophen, and uric acid at the highest physiological concentrations was below 4%. The SCGM1 System showed a reliable and precise performance under in vitro conditions.