Aggregation Number Research Articles

Confinement effect on the viscoelastic particle ordering in microfluidic flows: Numerical simulations and experiments

Strings of equally spaced particles, also called particle trains, have been employed in several applications, including flow cytometry and particle or cell encapsulation. Recently, the formation of particle trains in viscoelastic liquids has been demonstrated. However, only a few studies have focused on the topic, with several questions remaining unanswered. We here perform numerical simulations and experiments to elucidate the effect of the confinement ratio on the self-ordering dynamics of particles suspended in a viscoelastic liquid and flowing on the centerline of a microfluidic channel. For a fixed channel size, the particles self-order on shorter distances as the particle size increases due to the enhanced hydrodynamic interactions. At relatively low linear concentrations, the relative particle velocities scale with the fourth power of the confinement ratio when plotted as a function of the distance between the particle surfaces normalized by the channel diameter. As the linear concentration increases, the average interparticle spacing reduces and the scaling is lost, with an increasing probability to form strings of particles in contact. To reduce the number of aggregates, a microfluidic device made of an array of trapezoidal elements is fabricated and tested. The particle aggregates reduce down to 5% of the overall particle number, significantly enhancing the ordering efficiency. A good agreement between numerical simulations and experiments is found.

521 Supporting research through the development of self-service tools and operational transparency.

OBJECTIVES/GOALS: The Informatics Program in the Wake Forest CTSI is experiencing rapid growth. To accommodate an influx of both staff and clinical investigators this program Invests resources in self-service tools to increase researcher capabilities Automates resource intensive activities Creates transparency of operational processes for researchers. METHODS/STUDY POPULATION: Self-service tools (immediate/automated) The i2b2 tool queries clinical data for feasibility numbers and cohort identification; and provides demographic breakdowns of patient sets The Data Puller tool pulls identified patient data (with IRB approval) The SKAN NLP tool pulls aggregate numbers from over 3 million clinical notes Automation A custom-built tracking system automates parts of tracking requests for data and checking IRB protocols Operational transparency The Data Request Dashboard shows requesters information about their request and where it is in the process of being fulfilled The Data Quote tool was constructed leveraging the integrated CTSA informatics network and uses details of the request to estimate how long it will take to complete. RESULTS/ANTICIPATED RESULTS: i2b2 has had over 300 unique users each year; 80% are faculty or research staff, 20% are clinicians or students. From 2017-2021 there have been an average of 300 i2b2 queries and 45 Data Puller pulls each month. SKAN has had 58 unique users since its implementation in late 2020, averaging 5 new users per month. The automated data request tracking system took approximately 30 staff hours to create and saves an average of 4 hours of staff time per week. It also decreases human error by pulling/pushing information directly between systems. The Informatics program has received positive feedback from researchers who use the Data Request Dashboard. The Data Quote Tool is being used to give standardized quotes to researchers. DISCUSSION/SIGNIFICANCE: Investing resources in developing and implementing self-service tools and operational transparency ultimately reduces overall resource consumption, saving staff and investigator time and effort. This enables the Informatics program to maintain a high standard of service while experiencing rapid growth.

Role of core-shell structure in binary mixture of amino sulfonate amphoteric surfactant with nonionic surfactant in solubilization behavior of pyrene

In order to understand the role of core-shell structure of mixed surfactant micelle and the effect of hydrophilicity of amphiphile in the enhanced remediation of contaminated soils and water, a novel amphoteric sodium 3-(N-dodecylethylenediamino)− 2-hydroxypropyl sulfonate (C12AS), three nonionic octylphenol polyoxyethylated ethers with unit number n of oxyethylene glycol ether (OP-n, n = 4, 7 and 10) and these binary mixtures of C12AS/OP-n were adopted to probe the solubilization behavior of pyrene by both the UV–vis spectrometric and the 1H NMR techniques. Some parameters including the molar solubilization ratio (MSR), the partition coefficient (Pm), the standard free energy change (∆Gp) of partition, the interaction parameter (B) based on regular solution theory and the ratio (K1/n) of first stepwise association coefficient (K1) and aggregation number (n) in mixed micelle were estimated using different models. In these single surfactants, the values of MSR and Pm depend mainly on the hydrophilic-lipophilic balance (HLB) of amphiphiles for the homologues of OP surfactants. The solubilization behavior in these mixtures, however, does not again follow the HLB effect, but is subjected to the mixing ratio of component in mixed micelle and the micellar structure. The data from these B and K1/n values can gain some understanding in tune with these parameters, e.g., MSR, Pm, R, etc. Based on the chemical shift of hydroxyl group, the core-shell structure of mixed micelle assumed in this investigation is proposed to demonstrate the solubilization locus and rationally describe the spontaneous process of solubilization and the related behaviors. These findings will help with understanding the solubilization behavior of hydrophobic organic compounds in these surfactants with a core-shell structure of micelle and designing the surfactant formulations in the surfactant enhanced remediation of contaminated soils and water.

Identifying gender disparities in research performance: the importance of comparing apples with apples

Many studies on research productivity and performance suggest that men consistently outperform women. However, women and men are spread unevenly throughout the academy both horizontally (e.g., by scientific field) and vertically (e.g., by academic position), suggesting that aggregate numbers (comparing all men with all women) may reflect the different publication practices in different corners of the academy rather than gender per se. We use Norwegian bibliometric data to examine how the “what” (which publication practices are measured) and the “who” (how the population sample is disaggregated) matter in assessing apparent gender differences among academics in Norway. We investigate four clusters of indicators related to publication volume, publication type, authorship, and impact or quality (12 indicators in total) and explore how disaggregating the population by scientific field, institutional affiliation, academic position, and age changes the gender gaps that appear at the aggregate level. For most (but not all) indicators, we find that gender differences disappear or are strongly reduced after disaggregation. This suggests a composition effect, whereby apparent gender differences in productivity can to a considerable degree be ascribed to the composition of the group examined and the different publication practices common to specific groups. We argue that aggregate figures can exaggerate some gender disparities while obscuring others. Our study illustrates the situated nature of research productivity and the importance of comparing men and women within similar academic positions or scientific fields—of comparing apples with apples—when using bibliometric indicators to identify gender disparities in research productivity.

Binary micellar schemes of cationic gemini and conventional surfactants: chain length effect

Binary micellar schemes have been appropriated to ascertain the effect of chain length on micellization and interfacial properties. Mixed micellar systems of cationic gemini surfactant, bis-N,N-tetradecyldimethyl-m-phenylenediammonium dibromide (14-m-ɸ-14), and conventional cationic surfactants, viz., dodecyltrimethylammonium bromide (C12TAB), tetradecyltrimethylammonium bromide (C14TAB) and hexadecyltrimethylammonium bromide (C16TAB), in aqueous media were investigated by conductometric, tensiometric, fluorimetric and dynamic light scattering (DLS) techniques at 25 °C. The behavior of the binary mixtures under regular solution theory have been explained in light of Clint’s and Rubingh’s models. A non-ideal behavior was indicated. This was further confirmed by interaction parameter (β) values and activity coefficients. The synergism, an attractive interaction, between the surfactant molecules was ascertained. The average aggregation number () was evaluated by steady-state fluorescence quenching method. The increased with increase in mole fraction of CnTAB (n = 12, 14, 16). The size of the aggregates varied with length of conventional surfactants as exhibited by DLS. The zeta potential values of the mixed micelles increase with increase in mole fractions of CnTAB.

Adsorption of Cetylpyridinium Chloride at Silica Nanoparticle/Water Interfaces (II): Dependence of Surface Aggregation on Particle Size

Herein, we report a thermodynamic model that relates the adsorption (aggregation) parameters of surfactants at solid/liquid interfaces to particle radius (r). The adsorption (aggregation) parameters include adsorption amounts, equilibrium constants (or the standard Gibbs free energy changes), the critical surface micelle concentration (csmc), and the average aggregation number of surface micelles (n). The model predicts the size dependence of the surface aggregation of surfactants, which is determined by the changes in the interfacial tension and the molar volume of surface components caused by adsorption. In addition, the adsorption of cetylpyridinium chloride (CPyCl), a cationic surfactant, on silica nanoparticles with different r values (ca. 6-61 nm) was determined at 298 K and pH 4, showing an obvious size dependence, consistent with the prediction of the model. With an increase in r, the adsorption isotherm changes from the double-plateau type to the Langmuir type, accompanied by obvious changes in the adsorption parameters. The size-dependent adsorption data can be well described using the model equations, indicating that the model presented here is acceptable. In addition, the model can extract information on the interfacial tensions from adsorption data. We think that the model deepens the understanding of the aggregation phenomena of surfactants at solid/liquid interfaces.

Reactive astrocytes promote proteostasis in Huntington's disease through the JAK2-STAT3 pathway.

Huntington's disease is a fatal neurodegenerative disease characterized by striatal neurodegeneration, aggregation of mutant Huntingtin and the presence of reactive astrocytes. Astrocytes are important partners for neurons and engage in a specific reactive response in Huntington's disease that involves morphological, molecular and functional changes. How reactive astrocytes contribute to Huntington's disease is still an open question, especially because their reactive state is poorly reproduced in experimental mouse models. Here, we show that the JAK2-STAT3 pathway, a central cascade controlling astrocyte reactive response, is activated in the putamen of Huntington's disease patients. Selective activation of this cascade in astrocytes through viral gene transfer reduces the number and size of mutant Huntingtin aggregates in neurons and improves neuronal defects in two complementary mouse models of Huntington's disease. It also reduces striatal atrophy and increases glutamate levels, two central clinical outcomes measured by non-invasive magnetic resonance imaging. Moreover, astrocyte-specific transcriptomic analysis shows that activation of the JAK2-STAT3 pathway in astrocytes coordinates a transcriptional program that increases their intrinsic proteolytic capacity, through the lysosomal and ubiquitin-proteasome degradation systems. This pathway also enhances their production and exosomal release of the co-chaperone DNAJB1, which contributes to mutant Huntingtin clearance in neurons. Together, our results show that the JAK2-STAT3 pathway controls a beneficial proteostasis response in reactive astrocytes in Huntington's disease, which involves bi-directional signalling with neurons to reduce mutant Huntingtin aggregation, eventually improving disease outcomes.

Surface mechanical behavior of water-spread poly(styrene)–poly(ethylene glycol) (PS–PEG) micelles at the air–water interface: Effect of micelle size and polymer end/linking group chemistry

Hypothesis:The surface mechanical properties of poly(styrene)-poly(ethylene glycol) (PS–PEG) micelles are influenced by the PEG corona structure. Changes in micelle aggregation number as well as changes in the PEG end group and linking group chemistry of the PS–PEG block copolymer are expected to alter PEG corona characteristics and therefore affect surface mechanical properties of the resulting micelle film. Experiments:Different sized micelles comprised of PS–PEG block copolymer chains were formulated by equilibrating micelles in different ratios of acetone/water mixtures and subsequently removing acetone using dialysis. Additionally, micelles of a similar size and PS–PEG molecular weight but slightly different chemistry were formulated. The micelles were characterized using dynamic light scattering (DLS), transmission electron microscopy (TEM), 1H NMR, surface pressure–area isotherms and Brewster angle microscopy (BAM). Findings:The reduction in micelle aggregation number results in the subsequent monolayer having higher compressibility moduli and bending stiffnesses and collapsing at lower surface pressures. Micelle hydrophobicity was shown to improve readsorption of micelles to interface after collapse. Analysis of Brewster angle microscopy images of out-of-plane wrinkle structures which formed upon monolayer collapse indicates the presence of continuous 1 nm thick PEG layer which allows micelle monolayers to bend under high compression.

Nonlinear dynamics in micellar surfactant solutions. I. Kinetics.

This is the first of a pair of articles that present the theory of kinetic and transport phenomena in micelle-forming surfactant solutions in a form that facilitates discussion of large deviations from equilibrium. Our goal is to construct approximate but robust reduced models for both homogeneous and inhomogeneous systems as differential equationsfor unimer concentration c_{1}, micelle number concentration c_{m}, average micelle aggregation number q and (optionally) aggregation number variance σ_{m}^{2}. This first article discusses kinetics in homogeneous solutions. We focus particularly on developing models that can describe both weakly perturbed states and states in which c_{1} is suppressed significantly below the critical micelle concentration, which leads to rapid shrinkage and dissociation of any remaining micelles. This focus is motivated by the strong local suppression of c_{1} that is predicted to occur near interfaces during some adsorption processes that are considered in the second article. Toward this end, we develop a general nonlinear theory of fast stepwise processes for systems that may be subjected to large changes in q and c_{1}. This is combined with the existing nonlinear theory of slow association and dissociation processes to construct a general model for systems governed by stepwise reaction kinetics. We also consider situations in which the slow process of micelle creation and destruction instead occurs primarily by micelle fission and fusion, and analyze the dependencies of micelle lifetime and the slow relaxation time upon surfactant concentration in systems controlled by either association-dissociation or fission-fusion mechanisms.

Condition dependent self-aggregation behavior of aerosol-OT in mixed water-alcohol media: Physicochemical investigation

Amphiphiles aggregation in mixed aquo-organic solvent media has profound interest in the fields of chemistry, biology, pharmaceutics, and industry. Detailed fundamental understanding of the process in the bulk and at the interface is still remaining to be explored. In this report, the effect of two water miscible alkanols (ethanol (ET), and isopropanol (IP)) on the aggregation-behaviors of the surfactant sodium dioctylsulfosuccinate (Aerosol-OT or AOT) has been studied in a wide range of alcohol proportions (0 to 100 vol%) in water. Different physicochemical parameters like critical micelle concentration (CMC), counter-ion binding (β) and aggregation number (Nagg) of micelles, and the energetics of the AOT adsorption at the air/water interface, and its assembly formation in the bulk have been evaluated employing tensiometry and isothermal titration calorimetry (ITC) methods. The micelle forming region of AOT has been found to be 0–30 vol% for ET, and 0–20 vol% for IP. At [solvent] > 30 vol% the possibility of formation of “randomly arranged globular assembly” (RAGA) of the amphiphile [1] prevailed. Role of different solvent parameters have been attempted to explain the thermodynamics of the micellization process of AOT. SANS experiments have supported vesicle formation of concentrated solutions of AOT in 50 vol% ET or IP in water; with increasing alcohol vesicles transformed into micelles. DFT (density functional theory) calculations have been made for understanding the intermolecular interactions in AOT-H2O-ET or IP systems compared to their binary mixtures (AOT-H2O; AOT-ET; AOT-IP). NMR study has supported favorable interactions of the alkanols (ET and IP) with the head group of the AOT. Formation of micelles and reverse micelles by AOT in different composition of alcohols and pure alcohols reported by Michor and Berg [2] has been reasoned out to be incorrect.

Nonlinear dynamics in micellar surfactant solutions. II. Diffusion

We discuss diffusion in micellar surfactant solutions in a form appropriate for analyzing experiments that involve large deviations from equilibrium. A general nonlinear dynamical model for inhomogeneous systems is developed that describes the effects of diffusion and micelle kinetics as a set of coupled partial differential equationsfor unimer concentration, micelle number concentration, average micelle aggregation number, and, optionally, the variance of the micelle aggregation number. More specialized models are developed to describe slow dynamics in situations in which the system stays in a state of partial local equilibrium or full local equilibrium. As an illustrative example of a nonlinear transport phenomenon, we discuss a simple model of diffusion from an initially homogeneous micellar solution to a rapidly created absorbing interface with fast unimer adsorption.

Effects of Ion Content on the Ion Aggregation Morphology and Glass Transition of Poly(styrene-ran-cinnamic acid) (SCA) Zn-Salt Ionomer

Poly(styrene-ran-cinnamic acid) (SCA) Zn-salt ionomers (SCA‒Zn) bearing increasing contents (0, 0.23, 0.55, 1.3, 3.0, and 5.5 mol%) of Zn2+ ions were successfully synthesized by solution neutralization of the SCA with Zn2+ ions at room temperature. As the ion content of the SCA‒Zn increased from 0 to 5.5 mol%, the size and the aggregation number of the ionic aggregates did not change significantly, because the increase in ion content led to a monotonic increase in the number density of ionic aggregates, while the number of ions participating in the aggregates to form ionic aggregates was essentially fixed. Furthermore, the T g values of the SCA‒Zn increased slowly as the Zn2+ ion content increased, and the linear increase rate with Zn2+ ion content was ∼0.8 °C mol−1, which was quite different from the reported increase rate in the T g values of the matrix phase with Na+ ion content of 3–6 °C mol−1. This appeared to be caused by the steric hindrance effect of the adjacent groups of –COO− ions in the SCA and the long-distance electrostatic attraction. In addition, the degree of ionization of the SCA‒Zn was too low to cause large changes in thermal stability.

Coarse-Grained Molecular Dynamics Simulations of Paclitaxel-Loaded Polymeric Micelles.

A continuous manufacturing technology based on coaxial turbulent jet in coflow was previously developed to produce paclitaxel-loaded polymeric micelles. Herein, coarse-grained molecular dynamics (CG-MD) simulations were implemented to better understand the effect of the material attributes (i.e., the drug-polymer ratio and the ethanol concentration) and process parameters (i.e., temperature) on the self-assembly process of polymeric micelles as well as to provide molecular details on micelle instability. An all-atom (AA) poly (ethylene glycol)-poly (lactic acid) (PEG-PLA) polymer model was developed as the reference for parameterizing a coarse-grained (CG) model, and the AA polymer model was further validated with experimental glass transition temperature (Tg). The model transferability was verified by comparing structural properties between the AA and CG models. The CG model was further validated with experimental data, including micelle particle size measurements and drug encapsulation efficiency. Furthermore, the encapsulation of paclitaxel into the polymeric micelles was included in the simulations, taking into consideration the interactions between the paclitaxel and the polymers. The results from various points of view demonstrated a strong dependence of the shape of the micelles on the drug encapsulation, with micelles transitioning from spherical to ellipsoidal structures with an increasing paclitaxel amount. Simulation data were also used to identify the critical aggregation number (i.e., the number of polymer and drug molecules required for transition from one shape to another). Improved micellar structural stability was found with a larger micellar size and less solvent accessibility. Lastly, an evaluation was performed on the micellar dissociation free energy using a steered molecular dynamics simulation over a range of temperatures and ethanol concentrations. These simulations revealed that at higher ethanol and temperature conditions, micelles become destabilized, resulting in greater paclitaxel release. The increased drug release was determined to originate from the solvation of the hydrophobic core, which promoted micellar swelling and an associated reduction in hydrophobic interactions, leading to a loosely packed micellar structure.

Solubilization of aqueous-insoluble phenothiazine drug in TX-100 micellar solution and interactions of cationic/anionic surfactants with phenothiazine–TX-100 system

This article discusses the interaction of surfactants such as tetradecyltrimethylammonium bromide (TTAB), hexadecyltrimethylammonium bromide (CTAB), cetylpyridinium chloride (CPC), cetylpyridinium bromide (CPB) and sodium dodecylsulphate (SDS) in presence of poorly soluble drug phenothiazine (PTZ) in triton X-100 (TX-100) micellar aqueous media through the investigation of different physicochemical parameters. The interaction of surfactants in PTZ–TX-100 media has been studied using conductometric technique at pH 7.4 (SP buffer) and at three temperatures. The conductometric results reveal the sequence of critical micelle concentration (CMC) values of surfactants as SDS > TTAB > CPC > CPB > CTAB. UV–vis spectroscopy studies were used to learn the interactions of surfactants with the drug PTZ in TX-100 aqueous media (at 303.15 K and pH 7.4) which suggest the interactions are highly feasible (change of Gibbs energy; ΔGb < 0) and greatly improve beyond the CMC values of corresponding surfactants. The estimated parameters using the Benesi–Hildebrand equation indicate higher binding constant (Kb) for cetylpyridinium surfactants and least for SDS and the drug–surfactant complex formations are found to be in 1:2 stoichiometric ratios. Fluorescence technique has also been employed to study the aggregation number (Nagg), Stern-Volmer constant (KSV) and micro-polarity of TTAB/CTAB/SDS in PTZ–TX-100 systems at 303.15 K. The evaluated thermodynamic parameters such as change in Gibbs energy (ΔGm0), enthalpy (ΔHm0) and entropy (ΔSm0) of micellization show the process of micellization of all studied surfactants in PTZ–TX-100 aqueous media are spontaneous and exothermic.

THE EFFECT OF BRAND PERSONALITY ON TRUST, ATTACHMENT, AND COMMITMENT TO THE BRAND IPHONE USERS – CASE STUDY TANGERANG RAYA

Abstract: The purpose of this research is to offer a model that incorporates both direct and indirect effects of brand’s perceived personality on three major relational consequences of this construct: trust, attachment, and commitment to the brand. In addition to the links between brand personality and its relational consequences, the interdependence links amongst these consequences are also considered. The objectives of this research was : (a) brand personality have an effect on trust in the brand, (b) brand personality have an effect on attachment in the brand, (c) brand personality have an effect on commitment in the brand, (d) trust in the brand have an effect on attachment in the brand, (e) attachment in the brand have an effect on commitment in the brand.Brand personality plays an important role in creating a brand, and plays an important role in brand attributes, because consumers look for products that reflect their own image. The design of this research applies a survey toward unit of analysis onconsumers iPhone to interview for testing hypothesis. Meanwhile the required data consist of four variables; brand personality as independent variable, trust in the brand and attachment to the brand as intervening variables and commitment to the brand asdependent variable. The aggregate numbers of consumers iPhone that being respondent of the study are 185. Data analysis used in this research was consists of Structural Equation Method by AMOS 7.0 as software. The result of this research conclude that variable of brand personality had an effect on trust and commitment in the brand, and didn’t had an effect on attachment in the brand, trust in the brand have an effect on attachment in the brand and attachment in the brand have an effect on commitment in the brand. Keywords: brand personality, trust, attachment, and commitment.

Investigation of the synergistic effect and the morphology of the binary compound systems with potassium N-lauroyl glycinate

Abstract Potassium N-lauroyl glycinate (PLG) is an amino acid surfactant widely used in detergents and has excellent chemical properties. In the present work, PLG was mixed in different molar ratios (α1) with the commonly used amphoteric surfactant lauryl amidopropyl betaine (LAB) or the non-ionic surfactant alkyl glycoside (APG). Subsequently, the surface tension, average hydrodynamic radius and number of micellar aggregates of the individual surfactants and the compound systems were measured using the hanging plate method, dynamic light scattering and fluorescence probe method, respectively, and the corresponding surface activity parameters were calculated. The results show that the binary PLG/LAB and PLG/APG systems exhibit non-ideal behaviour and that there was mutual attraction in the systems. The broad distribution of the micelle radius of the PLG/LAB compound system indicates that there are two types of micelles, namely spherical and rod-shaped in the systems. The distribution of the micelle radius of the PLG/APG compound system decreases to the minimum value at α 1 = 0.5. At α 1 = 0.7 and 0.9, double peaks and a broad distribution were also observed. The number of micelle aggregates in the PLG/LAB and PLG/APG compound systems is less than that of the individual surfactants at the respective mole fractions.

Cluster-cluster interaction in nanodiamond hydrosols by small-angle scattering

The structure and interaction of nanodiamond fractal clusters were studied by small-angle X-ray and neutron scattering including contrast variation. The density of nanodiamonds, the aggregation number, and the ratio of aggregated/non-aggregated particles were determined. The analysis of the structure-factor made it possible to obtain the effective potential of cluster–cluster interaction. Branched fractal colloids behave to a certain extent like hard spheres, but the effective correlation length decreases with increasing concentration up to the sol–gel transition. The proposed approach for analyzing cluster–cluster correlations can be used in wider class of liquid systems with nano-sized non-compact inclusions.

Development of mathematical description of mechanical characteristics of integrated multi-motor electric drive for drying plant

More than 60 % of electric energy in industry and agriculture is consumed by an electric drive. In a number of production mechanisms, machines and aggregates of various industries, synchronous rotation of several electric motors connected to each other mechanically, electrically or technologically is needed. This requires the use of more complex methods of controlling electromechanical systems, since two or more electric motors must work in concert for one load, which, in turn, entails the use of a new element base, power and control, allowing to implement these technological cycles of work. The object of research is a three-motor electromechanical system interconnected and operating according to the “electric working shaft” (EWS) system. The main fundamental difference from earlier works is that they consider a system of coordinated rotation of only two asynchronous motors, respectively, only one misalignment angle between two asynchronous motors was taken into account. At the same time, the conclusions of the moments and currents of the motors were significantly simplified. In the proposed study, the number of consistently (synchronously) rotating motors from three and above is taken into consideration. In this case, the number of misalignment angles is assumed to be equal to the number of engines, that is, three involved in rotation. The analytical expressions of the basic electromechanical relations of the “electric working shaft” system with the regulation of the supply voltage are developed. A method is proposed for calculating the statistical characteristics of the regulated EWS system, which is easy to use and allows calculations in a wide range of rotor misalignment angles at various engine loads

Structure and ablation behavior of “Z-pins like” M-MC1-x (M = Zr, Hf) gradient cermet rods prepared by carbon diffusion in situ reaction method

In this study, “Z-pins like” M-MC1-x (M = Zr, Hf) gradient cermet rods were prepared by the carbon diffusion in situ reaction method, and the effects of different heat treatment temperatures on the microstructure of MC layers in “Z-pins like” M-MC1-x gradient cermet rods and the ablation behavior of “Z-pins like” M-MC1-x gradient cermet rods were investigated. The results showed that “Z-pins like” M-MC1-x (M = Zr, Hf) gradient cermet rods formed gradient MC layer after heat treatment, and the thickness of MC layer increased with the increase of heat treatment temperature, and the in situ reaction method improved the bonding conditions of different phase interfaces. The ablation performance of “Z-pins like” M-MC1-x cermet rods was good. After ablation, the “Z-pins like” M-MC1-x cermet rods formed multilayer structure inside, from the surface oxide layer to the substrate: partially molten MO2 layer, loose MO2 skeleton, MO2 layer formed by a large number of nanoscale microcrystalline aggregates, dense MCxOy layer and unoxidized MC1-x and M-MC1-x eutectic phases.

International Association for the Study of Lung Cancer Study of the Impact of Coronavirus Disease 2019 on International Lung Cancer Clinical Trials

IntroductionTo evaluate the effects of the global coronavirus disease 2019 (COVID-19) pandemic on lung cancer trials, we surveyed investigators and collected aggregate enrollment data for lung cancer trials across the world before and during the pandemic. MethodsA Data Collection Survey collected aggregate monthly enrollment numbers from 294 global lung cancer trials for 2019 to 2020. A 64-question Action Survey evaluated the impact of COVID-19 on clinical trials and identified mitigation strategies implemented. ResultsClinical trial enrollment declined from 2019 to 2020 by 14% globally. Most reductions in enrollment occurred in April to June where we found significant decreases in individual site enrollment (p = 0.0309). Enrollment was not significantly different in October 2019 to December of 2019 versus 2020 (p = 0.25). The most frequent challenges identified by the Action Survey (N = 172) were fewer eligible patients (63%), decrease in protocol compliance (56%), and suspension of trials (54%). Patient-specific challenges included access to trial site (49%), ability to travel (54%), and willingness to visit the site (59%). The most frequent mitigation strategies included modified monitoring requirements (47%), telehealth visits (45%), modified required visits (25%), mail-order medications (25%), and laboratory (27%) and radiology (21%) tests at nonstudy facilities. Sites that felt the most effective mitigation strategies were telehealth visits (85%), remote patient-reported symptom collection (85%), off-site procedures (85%), and remote consenting (89%). ConclusionsThe COVID-19 pandemic created many challenges for lung cancer clinical trials conduct and enrollment. Mitigation strategies were used and, although the pandemic worsened, trial enrollment improved. A more flexible approach may improve enrollment and access to clinical trials, even beyond the pandemic.