Initial Rate Research Articles

Artificial saliva induced structural breakdown of surimi gels with starch under continuous compressive motions

Food texture perception is dynamic, influenced by food properties and oral processing. Using the Repeatable Dual Extrusion Cell (RDEC), the oral processing dynamics of surimi gel with different corn starch concentrations (0–15%) in the presence of 1 ml artificial saliva or water were studied. The force-time curve showed increased peak forces with higher corn starch concentrations, peaking significantly at 10%, then decreasing at 15%. Salivary amylase played a crucial role in gel sample degradation, especially in samples with 5% starch, with a work value depletion ratio of 0.535 for sample with 1 ml water (SGW-5) and 0.406 for sample with 1 ml saliva (SGS-5). SEM analysis confirmed the formation of a continuous starch network with reduced intermolecular spaces in SGS-5. The starch-iodine complex showed decreasing order with increasing starch concentration, and SGS-5 exhibited the highest degradation rate (61.61 ± 0.92%). Mathematical modeling revealed that initial decay rates (k1) in gel sample decreased with increasing starch concentration, and samples with starch and artificial saliva had higher initial degradation rates. These findings highlight the intricate interplay between saliva and starch in the surimi gel matrix under continuous compressive motions by RDEC apparatus, providing insights for formulating food products with tailored textures properties.

The effect of incentive policies on the diffusion of construction and demolition waste recycling: A government perspective.

Construction and demolition (C&D) waste recycling plays a significant role in waste reduction and carbon reduction, which is critical for sustainable development. However, due to various limitations such as financial problems, C&D waste recycling industry is not well developed in developing countries. To address this problem, this study combines complex network theory and evolutionary game theory to analyse the diffusion of C&D waste recycling behaviour among enterprises under governmental incentive policies within a complex network context. The results demonstrate that the size of the network has limited effects on behaviour diffusion in Watts-Strogatz small-world network. Additionally, the study highlights the clear impact of governmental incentive probability, initial rate and connection degree on the diffusion path. By quantitatively investigating the effects of incentive tools, this study contributes to the knowledge of C&D waste management and provides valuable implications for stakeholders seeking to promote the diffusion of C&D waste recycling.

Hydration properties of magnesium phosphate cement paste mixed with metakaolin and silica fume

AbstractMagnesium phosphate cement (MPC) exhibits a faster setting time and higher early strength, making it suitable for crack repair. However, its application in civil engineering is hindered by its fast initial hydration rate and poor water resistance. To address these limitations, metakaolin (MK) and silica fume (SF) were utilized to enhance the properties of MPC. The effects of MK and SF on the setting time, compressive strength, water resistance, hydration process, and microstructure of MPC were investigated. The results demonstrate that both MK and SF significantly prolong the setting time of MPC and improve its water resistance. The main hydration products of MPC, after incorporating MK and SF, are k‐struvite (MgKPO4·6H2O) and unreacted MgO. The presence of MgSiO3 and AlPO4 also contributes to the enhancement of compressive strength and water resistance. The incorporation of MK and SF actively participates in the hydration reaction of the MPC system. Furthermore, MgSiO3 and AlPO4 intertwine with MKP, resulting in a denser internal structure of the cured MPC, thereby improving its water resistance.

High-Strength Copper/Silver Alloys Processed by Cold Spraying for DC and Pulsed High Magnetic Fields

High-strength, high-conductivity copper/silver-alloyed materials were prepared by cold-spray (CS) manufacturing. For DC high-field application at room temperature, bulk Cu/Ag (5% vol. Ag) alloys with high mechanical properties and high electrical conductivity can be obtained by CS and post-heat treatments. For pulsed-field application at liquid nitrogen temperature, bulk Cu/Ag (5% vol. Ag) alloys serve as precursors for room-temperature wire drawing. The Cu/Ag-alloyed bulk CS deposit presents a high yield strength of about 510 MPa with a corresponding electrical resistivity of 1.92 µΩ·cm (at 293 K). The Cu/Ag-alloyed wires show a very high ultimate tensile strength (1660 MPa at 77 K or 1370 MPa at 293 K) and low electrical resistivity (1.05 µΩ·cm at 77 K or 2.56 µΩ·cm at 293 K). Microstructural studies via STEM allow us to understand this very high level of mechanical strength. The results evidence that materials developed by CS exhibit very high mechanical properties compared to materials prepared by other routes, due to the high velocity of the deposited particles, which leads to high initial deformation rates and specific microstructural features.

Adsorption mechanism and interactions of coal particles modified with a novel hyperbranched dispersant

This account, a hyperbranched dispersant (Es-SAF-DBM-PSS) was assembled with the skeleton of Es-SAF-DBM (the functional modification of hydroquinone-based sulfonated acetone formaldehyde (SAF)) and numbers of linear polystyrene sodium sulfonate (PSS) chains by single electron transfer living radical polymerization (SET-LRP) in the system of PhBr2m4/Cu wire/PMDETA. The structure of the synthesized Es-SAF-DBM-PSS was detected by FTIR, 1H NMR, XPS, UV and GPC. Series of tests about the polymerization kinetics of Es-SAF-DBM-PSS were executed. Effects of temperatures and initiator concentration on the apparent polymerization rate were investigated, the results showed the low activation energy and higher initiation rate fitted the characteristic of SET-LRP. The rheological behaviors of Es-SAF-DBM-PSS as dispersant applied to coal water slurry (CWS) were tested. The following results were found as expected: the best usage of Es-SAF-DBM-PSS was only 0.3%, maximum coal content reached 63.7%, the viscosity dropped as low as 1000mPa·s. And the penetration ratio of slurry mixed with Es-SAF-DBM-PSS was still 100% even after 35days. Adsorption mechanism and interparticle interactions of coal particles modified with Es-SAF-DBM-PSS were investigated by Langmuir equation, dynamic equations and extended Derjaguin-Landau-Verwey-Overbeek (eDLVO) theory, the results showed the excellent dispersion and stability performance of Es-SAF-DBM-PSS were mainly related to the specific hyperbranched structure.

<i>Diospyros</i> <i>crassiflora</i> (HIERN) surface and subsoil leaf litter decomposition pattern along a time gradient in a humid rainforest

Litter decomposition is a crucial bedrock of nutrient recycling, organic matter accumulation, soil physicochemical properties, biodiversity and life support of forest and agroforestry systems. We therefore investigated <i>Diospyros</i> <i>crassiflora</i> surface and subsoil leaf litter decomposition pattern along a duration gradient in a humid rainforest. The study was conducted in the nursery of the humid forest research station of the Forestry Research Institute of Nigeria (FRIN) in Umuahia, Abia State. One gram (1g) of <i>D.</i> <i>crassiflora</i> fresh leaf litter was placed on the surface and subsoil of 4kg of topsoil contained in 32cm x 20cm polyethene bags; there were a total of 108 bags in a completely randomized experimental design layout and the treatments were the duration gradient of litter decomposition which were: 2, 4, 6, 8, 10, 12, and 14 weeks; on each of the duration, litter was collected from nine of the polyethene bags for laboratory analysis and estimate of decomposition rate. The results showed a significantly high initial decomposition rate (3.19±0.13 %day-1; 4.28±0.03 %day-1) in the 2 week duration followed by significant continuous decline until the lowest (0.04±0.00%day-1; 0.28±0.02%day-1) in the 14 week in the surface and subsoil respectively. There was a positive correlation (r=0.80) in decomposition rate between the surface and subsoil leaf litter, which yielded a model with a significant R2 (0.64), for site-specific estimates of decomposition rate <i>D.</i> <i>crassiflora</i> leaf litter. A steeper and smoother subsoil cumulative percentage decomposition curve showed that leaf litter decomposition was significantly faster in the subsoil than surface soil.

Mechanophotocatalysis: A Generalizable Approach to Solvent‐minimized Photocatalytic Reactions for Organic Synthesis

AbstractThis proof‐of‐concept study cements the viability and generality of mechanophotocatalysis, merging mechanochemistry and photocatalysis to enable solvent‐minimized photocatalytic reactions. We demonstrate the transmutation of four archetypal solution‐state photocatalysis reactions to a solvent‐minimized environment driven by the combined actions of milling, light, and photocatalysts. The chlorosulfonylation of alkenes and the pinacol coupling of aldehydes and ketones were conducted under solvent‐free conditions with competitive or superior efficiencies to their solution‐state analogues. Furthermore, decarboxylative alkylations are shown to function efficiently under solvent‐minimized conditions, while the photoinduced energy transfer promoted [2+2] cycloaddition of chalcone experiences a significant initial rate enhancement over its solution‐state variant. This work serves as a platform for future discoveries in an underexplored field: validating that solvent‐minimized photocatalysis is not only generalizable and competitive with solution‐state photocatalysis, but can also offer valuable advantages.

Mechanophotocatalysis: A Generalizable Approach to Solvent-minimized Photocatalytic Reactions for Organic Synthesis.

This proof-of-concept study cements the viability and generality of mechanophotocatalysis, merging mechanochemistry and photocatalysis to enable solvent-minimized photocatalytic reactions. We demonstrate the transmutation of four archetypal solution-state photocatalysis reactions to a solvent-minimized environment driven by the combined actions of milling, light, and photocatalysts. The chlorosulfonylation of alkenes and the pinacol coupling of aldehydes and ketones were conducted under solvent-free conditions with competitive or superior efficiencies to their solution-state analogues. Furthermore, decarboxylative alkylations are shown to function efficiently under solvent-minimized conditions, while the photoinduced energy transfer promoted [2+2] cycloaddition of chalcone experiences a significant initial rate enhancement over its solution-state variant. This work serves as a platform for future discoveries in an underexplored field: validating that solvent-minimized photocatalysis is not only generalizable and competitive with solution-state photocatalysis, but can also offer valuable advantages.

Validation of the Kidney Failure Risk Equation in the Colombian Population.

Chronic kidney disease prevention programs must identify patients at risk of early progression to provide better treatment and prolong kidney replacement therapy-free survival. Risk equations have been developed and validated in cohorts outside of Colombia, so this study aims to evaluate the discrimination and calibration of the four-variable kidney failure risk equation in a Colombian population where it has yet to be validated. External validation study of a kidney failure risk equation using a historical cohort of patients with CKD stages 3, 4, and 5, adults without a history of dialysis or kidney transplantation with a two-year follow-up, belonging to the Baxter Renal Care Services Colombia network. The discriminatory capacity of the model was evaluated by the concordance index using Harrell's C statistic, and the time-dependent area under the receiver operating characteristic (ROC) curve was estimated using the nearest neighbor method, as well as the optimal cut-off point for sensitivity and specificity. Calibration was determined by the degree of agreement between the observed outcome and the probabilities predicted by the model using the Hosmer-Lemeshow statistic. A total of 5,477 patients were included, with a mean age of 72 years, 36.4% diabetic, and a mean baseline eGFR of 36 ml/min/1.73 m2. The rate of dialysis initiation was three events per 100 patient-years, 95% CI (2.9-3.6). The optimal cutoff for sensitivity was 0.94, for specificity, 0.76, and the area under the ROC curve was 0.92. Harrell's C-statistic was 0.88 for the total population, 0.88 for diabetic patients, and 0.93 for those 65 years or older. The validation of the model showed good calibration. In this Colombian cohort, the four-variable KFRE with a two-year prediction horizon has excellent calibration and discrimination, and its use in the care of CKD Colombian patients is recommended.

Modelling method of heterogeneous rock mass and DEM investigation of seepage characteristics

The Weibull distribution is used to describe the heterogeneity of rock hydraulics and embedded into the Fish program which is based on the discrete element method. The developed program overcomes the limitation of the Universal Distinct Element Code (UDEC) software regarding the number of parameter groups, which cannot exceed 50. A method for parameter assignment of heterogeneous rocks is proposed together with a method for estimating the initial flow rate value of heterogeneous models. Based on the established heterogeneity calculation model, the influence of block homogeneity, hydraulic aperture homogeneity, and stress on the seepage characteristics is studied. The results indicate that under zero stress conditions, the flow rate is positively correlated with N0.5 showing a strong linear relationship. The linear relationship is gradually enhanced with the increase in the shape parameters. The relationship between the flow rate and shape parameters is logarithmic with a correlation coefficient greater than 0.9654. The relationship between the flow rate and the axial pressure and confining pressure can be described by quadratic and cubic polynomials, respectively, based on which we further discuss the variation characteristics of equivalent hydraulic apertures under the various axial pressures, confining pressures, and shape parameters.

Modified endoscopic retrograde appendicitis therapy vs. laparoscopic appendectomy for uncomplicated acute appendicitis in children.

Modified endoscopic retrograde appendicitis therapy (mERAT) has been proposed as an alternative to laparoscopic appendectomy for the treatment of appendicitis. However, data from children in large samples are lacking. The aim of this article is to evaluate the efficacy between mERAT and laparoscopic appendectomy (LA) in children with uncomplicated appendicitis. We retrospectively analyzed 594 patients with suspected uncomplicated appendicitis from October 2018 to May 2021. A pool of 294 consecutive patients who met the inclusion criteria were ultimately enrolled in this study (228 and 66 patients in mERAT and LA, respectively). Given the differences in baseline clinical data (gender, age), the regression equation including differences in clinical baseline, grouping factor, and white blood cell count was established to address the influence of potential confounding factors. The initial success rate of mERAT management was 96.9%, and the recurrence rate was 6.9% in the mERAT group and 1.7% in the LA group within 1 year, which was no significant difference. But the mERAT group had a lower rate of adverse events. Finally, those results indicated that the treatment modalities, LA or mERAT, had no significant effect on initial success rate (P = 0.99) or recurrence rate (P = 0.17) within 1 year, but a significant effect on the adverse events rate during hospitalization (P = 0.01) in the multivariate regression analysis. Among children with uncomplicated appendicitis, an initial mERAT management strategy had a success rate of 96.9%, which was similar to the LA group at 1 year. This follow-up supports the feasibility of mERAT alone as an alternative to surgery for uncomplicated appendicitis.

Approaches for bridging therapy prior to chimeric antigen receptor T cells for relapsed/refractory acute lymphoblastic B-lineage leukaemia in children and young adults.

The ongoing development of immunotherapies, including chimeric antigen receptor (CAR) T cells, has revolutionized cancer treatment. In paediatric relapsed/refractory B-lineage acute leukaemia antiCD19-CARs induced impressive initial response rates, with event-free survival plateauing at 30-50% in long-term follow-up data. During the interval between diagnosis of relapse or refractoriness and CAR T cell infusion, patients require a bridging therapy. To date, this therapy has consisted of highly variable approaches based on local experience. Here, in an European collaborative effort of paediatric and adult haematologists, we summarise current knowledge with the aim of establishing a guidance for bridging therapy. This includes treatment strategies for different patient subgroups, the advantages and disadvantages of low- and highintensity regimens, and the potential impact of bridging therapy on outcome after CAR T cell infusion. This guidance is a step towards a cross-institutional harmonization of bridging therapy, including personalized approaches. This will allow better comparability of clinical data and increase the level of evidence for the treatment of children and young adults with relapsed/refractory B-lineage ALL until CAR T cell infusion.

Impact of initial high flow nasal cannula flow rates on clinical outcomes in children with bronchiolitis.

Our aim was to evaluate the impact of the initial high flow nasal cannula (HFNC) flow rate on clinical outcomes in children with bronchiolitis. This secondary analysis of retrospective data included children <2 years who required HFNC for bronchiolitis between 10/01/2018-04/20/2019, and following implementation of a revised institutional bronchiolitis pathway between 10/01/2021-04/30/2022. The new pathway recommended weight-based initiation of HFNC at 1.5-2 L/kg/min. We evaluated the effect of low (<1.0 L/kg/min), medium (1-1.5 L/kg/min) and high (>1.5 L/kg/min) HFNC flow rates on need for positive pressure ventilation (PPV), intensive care unit (ICU) transfer, HFNC treatment time, and hospital length of stay (LOS). The majority of the 885 included children had low initial flow rates (low [n = 450, 50.8%], medium [n = 332, 37.5%] and high [n = 103, 11.7%]). There were no significant differences in PPV (high: 7.8% vs. medium: 9.3% vs. low: 8.2%, p = 0.8) or ICU transfers (high: 4.9% vs. medium: 6.0% vs. low: 3.8%, p = 0.3). The low flow group had a significantly longer median HFNC treatment time (High: 29 [18, 45] vs. medium: 29 [16, 50] vs. low: 39 [25, 63], p < .001) and hospital LOS (High: 41 [27, 59] vs. medium: 42 [29, 66] vs. low: 50 (39, 75), p < .001). Logistic and linear regression models did not demonstrate any associations between HFNC flow rates and PPV or hospital LOS. Initial HFNC flow rates were not associated with significant changes in clinical outcomes in children in children with bronchiolitis.

Enzymatic Knoevenagel condensation in dual‐functionalized water‐mimicking ionic liquids and tertiary amide solvents

AbstractBACKGROUNDKnoevenagel condensation is an important tool for building carbon–carbon (CC) bonds, especially when catalyzed by enzymes to enable a potentially high chemo‐, regio‐ and/or stereoselectivity. Although many Knoevenagel condensation reactions are carried out in aqueous solutions, insoluble hydrophobic substrates often lead to poor catalytic efficiencies. The use of water‐miscible organic solvents improves the substrate solubilization, but usually induces activity suppression or inactivation of enzymes. There is a great need to develop alternative solvents for both substrate dissolution and enzyme compatibility in CC bond formation reactions.RESULTSOur group previously developed dual‐functionalized water‐mimicking ionic liquids (ILs) for the activation and stabilization of hydrolases (e.g. lipase and protease). In the present study, we evaluated the Knoevenagel condensation of 4‐chlorobenzaldehyde with acetylacetone, and found that porcine pancreas lipase in water‐mimicking ILs carrying ammonium, imidazolium and benzimidazolium cations enabled higher reaction rates (up to 3.22 μmol min−1 g−1 lipase) and better yields than tert‐butanol, glymes and [BMIM][Tf2N]. Interestingly, tertiary amide solvents such as N‐methyl‐2‐pyrrolidone (NMP), N,N‐dimethylformamide (DMF) and N,N‐dimethylacetamide (DMAc) led to 8.2‐ to 11.1‐fold increases in the initial rate (up to 35.66 μmol min−1 g−1 lipase) when compared with dual‐functionalized ILs, which is likely due to some synergistic effect of these tertiary amides with the lipase.CONCLUSIONDual‐functionalized ILs based on ammonium, imidazolium and benzimidazolium cations improved Knoevenagel condensation reaction rates and yields when compared with tert‐butanol and glymes. Tertiary amides (NMP, DMF and DMAc) significantly increased the reaction rate. © 2024 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley &amp; Sons Ltd on behalf of Society of Chemical Industry (SCI).

Intraoperative AI-assisted early prediction of parathyroid and ischemia alert in endoscopic thyroid surgery.

The preservation of parathyroid glands is crucial in endoscopic thyroid surgery to prevent hypocalcemia and related complications. However, current methods for identifying and protecting these glands have limitations. We propose a novel technique that has the potential to improve the safety and efficacy of endoscopic thyroid surgery. Our study aims to develop a deep learning model called PTAIR 2.0 (Parathyroid gland Artificial Intelligence Recognition) to enhance parathyroid gland recognition during endoscopic thyroidectomy. We compare its performance against traditional surgeon-based identification methods. Parathyroid tissues were annotated in 32 428 images extracted from 838 endoscopic thyroidectomy videos, forming the internal training cohort. An external validation cohort comprised 54 full-length videos. Six candidate algorithms were evaluated to select the optimal one. We assessed the model's performance in terms of initial recognition time, identification duration, and recognition rate and compared it with the performance of surgeons. Utilizing the YOLOX algorithm, we developed PTAIR 2.0, which demonstrated superior performance with an AP50 score of 92.1%. The YOLOX algorithm achieved a frame rate of 25.14 Hz, meeting real-time requirements. In the internal training cohort, PTAIR 2.0 achieved AP50 values of 94.1%, 98.9%, and 92.1% for parathyroid gland early prediction, identification, and ischemia alert, respectively. Additionally, in the external validation cohort, PTAIR outperformed both junior and senior surgeons in identifying and tracking parathyroid glands (p < 0.001). The AI-driven PTAIR 2.0 model significantly outperforms both senior and junior surgeons in parathyroid gland identification and ischemia alert during endoscopic thyroid surgery, offering potential for enhanced surgical precision and patient outcomes.

A Response Surface Methodology Study for Chlorella vulgaris Mixotrophic Culture Optimization.

Glycerol is a carbon source that produces good biomass under mixotrophic conditions. Enhancing the composition of culture media in algae biomass production improves growth rates, biomass yield, nutrient utilization efficiency, and overall cost-effectiveness. Among the key nutrients in the medium, nitrogen plays a pivotal role. Urea can be effectively used as a nitrogen source and is considered a low-cost form of nitrogen compared to other sources. Urea metabolism releases some CO2 in photosynthesis, and magnesium plays a major role in urea uptake. Magnesium is another key nutrient that is key in photosynthesis and other metabolic reactions. To maximize glycerol consumption in the mixotrophic system and to obtain high biomass and lipid productions, the variations in MgSO4·7H2O and urea concentrations were evaluated in the growth medium of the microalgae. A response surface methodology (RSM) using a central composite design (CCD) was designed to maximize glycerol consumption at the initial cellular growth rates (up to four days). The magnesium and urea supply varied from 0.3 to 1.7 g L-1. Response surface methodology was utilized to analyze the results, and the highest glycerol consumption rate, 770.2 mg L-1 d-1, was observed when C. vulgaris was grown at 1.7 g L-1 urea, 1.0 g L-1 MgSO4·7H2O. Using the optimal urea and magnesium concentrations with acetate, glucose, and glycerol as carbon sources, the same lipid content (10% average) was achieved on day 4 of mixotrophic C. vulgaris culture. Overall, the results show that mixotrophic growth of C. vulgaris using urea with an optimum magnesium concentration yields large amounts of fatty acids and that the carbon source greatly influences the profile of the fatty acids.

Gd2O3/CdS Nanocomposites were Synthesized for Photocatalytic Elimination of Methyl Blue (MB) Dye Under Visible Light Irradiation

Water contamination with hazardous dyes is a serious environmental issue that concerns humanity. A green technology to resolve this issue is the use of highly efficient photocatalysts under visible light to degrade these organic molecules. Adding composite and modifying shape and size on semiconductor materials are attempts to improve the efficacy of these compositions. The optical, microstructural and photocatalytic features of the compositions were investigated by several characterization procedures such as XRD, XPS, SEM, and TEM. Here, modifies Scherrer equation, Williamson–Hall (W–H), and Halder–Wagner method (H–W) have been used to investigate the crystal size and the micro-strain from the XRD peak broadening analysis. The average crystal size according to Modified Scherrer’s formula was 6.04–10.46 nm for pristine CdS and CdS/Gd2O3@GO, respectively. While the micro-strain (ɛ) corresponds to 3.88, 4.63, 4.03, and 4.15 for CdS, Gd2O3, CdS/Gd2O3, and CdS/Gd2O3@GO. It was also shown that the modest difference in average crystal size acquired by the Modified Scherrer and Halder–Wagner (HW) forms was related to differences in average particle size classification. As a result, the Halder–Wagner method was accurate in estimating crystallite size for the compositions. The average roughness is slightly changed from 4.4 to 4.24 nm for CdS/Gd2O3 and CdS/Gd2O3@GO, respectively. A kinetics investigation further revealed that the photocatalytic degradation of MB dyes was accompanied by a Langmuir isotherm and a pseudo-second-order reaction rate. The highest adsorption capacity (qe) determined for (type 1) CdS, Gd2O3, CdS/Gd2O3, and CdS/Gd2O3@GO adsorption was 5, 0.067, 0.027, and 0.012 mgg−1, respectively. The R2 values originated from the pseudo-second-order (type 2) for CdS, Gd2O3, CdS/Gd2O3, and CdS/ Gd2O3@GO were 0.904, 0,928, 0.825, and 0.977. As a result, the initial sorption rate (h) is altered between types 1 and 2. In type 2, the pseudo-second-order rate constant (k2) ranges from 0.005 for CdS to 0.011 for CdS/Gd2O3@GO. The Langmuir Hinshelwood and pseudo-second-order kinetic models describe the photodegradation process. The results demonstrate that the developed compositions can be used as a long-term substance for dye removal.

Fluid-Dynamic Mechanisms Underlying Wind Turbine Wake Control with Strouhal-Timed Actuation

A reduction in wake effects in large wind farms through wake-aware control has considerable potential to improve farm efficiency. This work examines the success of several emerging, empirically derived control methods that modify wind turbine wakes (i.e., the pulse method, helix method, and related methods) based on Strouhal numbers on the O(0.3). Drawing on previous work in the literature for jet and bluff-body flows, the analyses leverage the normal-mode representation of wake instabilities to characterize the large-scale wake meandering observed in actuated wakes. Idealized large-eddy simulations (LES) using an actuator-line representation of the turbine blades indicate that the n=0 and ±1 modes, which correspond to the pulse and helix forcing strategies, respectively, have faster initial growth rates than higher-order modes, suggesting these lower-order modes are more appropriate for wake control. Exciting these lower-order modes with periodic pitching of the blades produces increased modal growth, higher entrainment into the wake, and faster wake recovery. Modal energy gain and the entrainment rate both increase with streamwise distance from the rotor until the intermediate wake. This suggests that the wake meandering dynamics, which share close ties with the relatively well-characterized meandering dynamics in jet and bluff-body flows, are an essential component of the success of wind turbine wake control methods. A spatial linear stability analysis is also performed on the wake flows and yields insights on the modal evolution. In the context of the normal-mode representation of wake instabilities, these findings represent the first literature examining the characteristics of the wake meandering stemming from intentional Strouhal-timed wake actuation, and they help guide the ongoing work to understand the fluid-dynamic origins of the success of the pulse, helix, and related methods.

Evaluating methodological enhancements to the Yes/No Angoff standard-setting method in language proficiency assessment

This study evaluated the efficacy of two proposed methods in an operational standard-setting study conducted for a high-stakes language proficiency test of the U.S. government. The goal was to seek low-cost modifications to the existing Yes/No Angoff method to increase the validity and reliability of the recommended cut scores using a convergent mixed-methods study design. The study used the Yes/No ratings as the baseline method in two rounds of ratings, while differentiating the two methods by incorporating item maps and an Ordered Item Booklet, each of which is an integral tool of the Mapmark and the Bookmark methods. The results showed that the internal validity evidence is similar across both methods, especially after Round 2 ratings. When procedural validity evidence was considered, however, a preference emerged for the method where panelists conducted the initial ratings unbeknownst to the empirical item difficulty information, and then such information was provided on an item map as part of the Round 1 feedback. The findings highlight the importance of evaluating both internal and procedural validity evidence when considering standard-setting methods.

Intersubunit communication in glycogen phosphorylase influences substrate recognition at the catalytic sites

Glycogen phosphorylase (GP) is biologically active as a dimer of identical subunits, each activated by phosphorylation of the serine-14 residue. GP exists in three interconvertible forms, namely GPa (di-phosphorylated form), GPab (mono-phosphorylated form), and GPb (non-phosphorylated form); however, information on GPab remains scarce. Given the prevailing view that the two GP subunits collaboratively determine their catalytic characteristics, it is essential to conduct GPab characterization to gain a comprehensive understanding of glycogenolysis regulation. Thus, in the present study, we prepared rabbit muscle GPab from GPb, using phosphorylase kinase as the catalyst, and identified it using a nonradioactive phosphate-affinity gel electrophoresis method. Compared with the half-half GPa/GPb mixture, the as-prepared GPab showed a unique AMP-binding affinity. To further investigate the intersubunit communication in GP, its catalytic site was probed using pyridylaminated-maltohexaose (a maltooligosaccharide-based substrate comprising the essential dextrin structure for GP; abbreviated as PA-0) and a series of specifically modified PA-0 derivatives (substrate analogs lacking part of the essential dextrin structure). By comparing the initial reaction rates toward the PA-0 derivative (Vderivative) and PA-0 (VPA-0), we demonstrated that the Vderivative/VPA-0 ratio for GPab was significantly different from that for the half-half GPa/GPb mixture. This result indicates that the interaction between the two GP subunits significantly influences substrate recognition at the catalytic sites, thereby providing GPab its unique substrate recognition profile.