Short-term Stability Research Articles

A-163 Stability of apixaban in Li-heparin plasma stored refrigerated over mint green-top tube separator gel

Abstract Background Apixaban is a factor Xa inhibitor used as a direct oral anticoagulant (DOAC). The laboratory was asked to provide measurements of plasma apixaban in the context of studies regarding interaction of apixaban with other therapeutic drugs. One study involved isolation of plasma from to-be-discarded specimens, where such specimens were those originally collected in mint green-top tubes (Li-heparin tubes containing plasma separator gel), and that had been centrifuged and stored refrigerated for 5 days. Whereas apixaban concentration is known to be stable in refrigerated plasma specimens for up to two weeks, stability of apixaban concentration in plasma stored refrigerated for prolonged periods over plasma separator gel was unknown. Our objective was to examine stability of apixaban in plasma stored refrigerated for 5 days over plasma separator gel. Methods Pharmacy records were reviewed to identify inpatients who were prescribed apixaban, and for whom a mint green-top tube specimen (Becton-Dickinson BD Vacutainer PST Gel and Lithium Heparin, #367961) had been drawn for routine chemistry tests. From such specimens, 500 uL aliquots of plasma were obtained on day 1 (A) and day 5 (B) of storage under refrigeration (4 °C). Apixaban concentrations for A and B were measured by LC-MS/MS and compared. Additionally, short term (1 day) stability of apixaban was examined by comparison of replicate measurements of apixaban in a single spiked pooled purple-top plasma specimen (Becton-Dickinson BD Vacutainer K2 EDTA, #367856), with (C) or without (D) exposure to mint green-top tube separator gel for a 24h refrigeration period. Data analyses were conducted using R (version 4.0.5). Results A total of 21 specimen pairs (A, B) were examined. [Apixaban] ranged from 30-1000 ng/mL. The ratio B/A was 1.007 ± 0.034, consistent with no effect on plasma [apixaban] of refrigerated storage over separator gel between day 1 and day 5 (by paired t-test: p>0.8). Experiments for replicates of (C, D) specimens (n = 4, average [apixaban] = 410 ng/mL) gave D/C ratio of 1.009 ± 0.019, consistent with no effect on plasma [apixaban] of short term (1 day) refrigerated storage of plasma over separator gel (by paired t-test: p>0.4). Conclusions For plasma specimens collected and centrifuged in mint-green plasma separator tubes, there was no effect on plasma [apixaban] of refrigerated storage over separator gel for periods of 0-5 days.

A-317 Development of a patient-focused volumetric absorptive microsampling strategy to assess urinary amino acid excretion

Abstract Background Biochemical determinations of urinary amino acid excretion patterns can diagnose specific inborn errors of metabolism (IEM). Clinical management of these genetic metabolic patients may require frequent urine amino acid tests. A simplified process for transporting home collected urine specimens would benefit the IEM community. Volumetric absorptive microsampling (VAMS) is an emergent alternative sampling technique for the collection of dried biological specimens. We describe the development and preliminary validation results of a VAMS strategy for the analysis of creatinine and amino acids (N=22) from microsampled dried urine. Methods Urine creatinine and amino acids were respectively measured in a clinical laboratory setting using established assays on a CobasPro (Roche) and a MassTrak ultra-performance liquid chromatography (UPLC) amino acid analysis (AAA) solution (Waters). Two 30 µL VAMS tips from a Mitra device (Neoteryx) were used to sample each random urine specimen. An ultrasonication-based solvent extraction procedure was optimized to extract the amino acids and creatinine from the VAMS tips. Solvent extracts were subsequently dried by centrifugal evaporation. Extract from one tip was re-dissolved in water and tested for creatinine using an enzymatic method. The other extract was re-dissolved in 0.02 N sodium hydroxide and tested according to the MassTrak AAA procedure, which deploys pre-column AccQTag derivatization with reversed-phase UPLC on a C18 column (2.1 × 150 mm; 1.7 µm) and UV detection at 260 nm. Accuracy, within-batch precision and short-term stability of the optimized VAMS protocol were determined. Results Extraction solvent with a 60:40 (v/v) water:methanol mixture provided the highest average amino acid recovery. This extraction solvent produced higher average amino acid recoveries at pH 11 (89±13%), than pH 3 (82±10%) or pH 7 (72±11%). Creatinine measured from the VAMS tips (N=44) had a consistent negative bias of 20% relative to neat urine (R=0.9905, slope=0.802, intercept=0.02). The creatinine corrected urine amino acid results from the Mitra device were corrected for this observed concentration bias. The accuracy of the amino acid results derived from the VAMS tip vs neat urine was 104 ± 14%. The average within-batch precision (CV%) of the amino acids was 9.8% (range=6.7% (cystine) to 17.6% (arginine)) and 6.2% for creatinine. The average 1 week storage stability at ambient temperature was 91% (range=73% (ornithine) to 107% (glycine)) for the amino acids and 107% for creatinine. The devised VAMS strategy was applied to the analysis of microsampled dried urine from a patient with cystinuria (OMIM no. 220100). Marked elevations in arginine, cystine, lysine and ornithine were respectively observed and are consistent with the biochemical diagnosis of the patient. Conclusions Creatinine corrected amino acid results from the devised VAMS strategy exhibit good precision and accuracy when compared to tradition analyses of neat urine. The potential use of microsampled dried urine for the diagnosis and monitoring of selected IEM has been demonstrated. The analytical and clinical performance of this VAMS protocol must be further validated, including the use of microsampled dried urine from home specimen collections.

Influence of Peanut Consumption on the Gut Microbiome: A Randomized Clinical Trial.

Background: Peanut consumption could impact cardiometabolic health through gut microbiota, a hypothesis that remains to be investigated. A randomized clinical trial in Vietnam evaluated whether peanut consumption alters gut microbiome communities. Methods: One hundred individuals were included and randomly assigned to the peanut intervention and control groups. A total of 51 participants were provided with and asked to consume 50 g of peanuts daily, while 49 controls maintained their usual dietary intake for 16 weeks. Stool samples were collected before and on the last day of the trial. After excluding 22 non-compliant participants and those who received antibiotic treatment, 35 participants from the intervention and 43 from the control were included in the analysis. Gut microbiota composition was measured by shotgun metagenomic sequencing. Associations of changes in gut microbial diversity with peanut intervention were evaluated via linear regression analysis. Linear mixed-effects models were used to analyze associations of composition, sub-community structure, and microbial metabolic pathways with peanut intervention. We also performed beta regression analysis to examine the impact of peanut intervention on the overall and individual stability of microbial taxa and metabolic pathways. All associations with false discovery rate (FDR)-corrected p-values of <0.1 were considered statistically significant. Results: No significant changes were found in α- and β-diversities and overall gut microbial stability after peanut intervention. However, the peanut intervention led to lower enrichment of five phyla, five classes, two orders, twenty-four metabolic pathways, and six species-level sub-communities, with a dominant representation of Bifidobacterium pseudocatenulatum, Escherichia coli D, Holdemanella biformis, Ruminococcus D bicirculans, Roseburia inulinivorans, and MGYG-HGUT-00200 (p < 0.05 and FDR < 0.1). The peanut intervention led to the short-term stability of several species, such as Faecalibacterium prausnitzii F and H, and a metabolic pathway involved in nitrate reduction V (p < 0.05; FDR < 0.1), known for their potential roles in human health, especially cardiovascular health. Conclusions: In summary, a 16-week peanut intervention led to significant changes in gut microbial composition, species-level sub-communities, and the short-term stability of several bacteria, but not overall gut microbial diversity and stability. Further research with a larger sample size and a longer intervention period is needed to confirm these findings and investigate the direct impact of gut-microbiome-mediated health effects of peanut consumption. Trial registration: The International Traditional Medicine Clinical Trial Registry (ITMCTR). Registration number: ITMCTR2024000050. Retrospectively Registered 24 April 2024.

Limited Short-Term Evolution of SARS-CoV-2 RNA-Dependent RNA Polymerase under Remdesivir Exposure in Upper Respiratory Compartments.

The extent of the SARS-CoV-2 short-term evolution under Remdesivir (RDV) exposure and whether it varies across different upper respiratory compartments are not fully understood. Patients hospitalized for COVID-19, with or without RDV therapy, were enrolled and completed up to three visits, in which they provided specimens from four respiratory compartments. Near full-length genome SARS-CoV-2 sequences were obtained from viral RNA, standard lineage and variant assignments were performed, and viral mutations in the RNA-dependent RNA polymerase (RdRp) region-the RDV target gene-were detected and compared between participants with and without RDV, across the four compartments, within participants across visits, and versus a larger sequence dataset. The statistical analysis used a generalized linear mixed-effects model. A total of 139 sequences were obtained from 37 out of the 44 (84%) enrolled participants. The genotyping success varied across respiratory compartments, which ranged from 42% with oropharyngeal specimens to 67% with nasopharyngeal specimens and showed improvement with higher viral loads. No RdRp mutations known to be associated with RDV resistance were identified, and for 34 detected mutations at 32 amino acid positions that are not known as RDV-associated, there was no evidence of any associations with the RDV exposure, respiratory compartment, or time. At least 1 of these 34 mutations were detected in all participants, and some differed from the larger sequence dataset. This study highlighted the SARS-CoV-2 short-term genomic stability within hosts and across upper respiratory compartments, which suggests a lack of evolution of RDV resistance over time. This contributes to our understanding of SARS-CoV-2 genomic dynamics.

Stability and Volatility in Cultural Models of Contention

Abstract How stable are the public’s assumptions about the legitimacy of contentious tactics? Previous studies show that the public hold a set of assumptions about what counts as legitimate and illegitimate tactics. We enrich this literature by studying the stability of these assumptions through the case of partisan protesting in the United States. Leveraging panel data collected during the 2020 Black Lives Matter and anti-lockdown protests as well as two preregistered survey experiments, we provide the first methodologically rigorous study of the short-term stability of these assumptions. We find that tactics are understood as inherently more legitimate when they are currently carried out by members of the partisan ingroup as opposed to its outgroup. However, although we do find an effect of contention, this is relatively moderate. The assumptions remain remarkably stable. This underscores the consolidated nature of the tactics in the United States and tempers fears of democratic decline in the realm of contention.

Psychometric Validation of the Slovenian Version of the Revised Child Anxiety and Depression Scale - Child and Parent Versions (RCADS and RCADS-P)

Abstract Objective Anxiety and depression are common disorders in children and adolescents and can have a negative impact on their lives. The Revised Child Anxiety and Depression Scale – Child and Parent versions (RCADS and RCADS-P) are widely used standardized measurement tools, but the Slovenian versions have not yet been validated. The aim of the present study was to examine the psychometric properties of the Slovenian version of RCADS and RCADS-P in a representative Slovenian school sample. Methods We examined the psychometric properties (factor structure, internal reliability, short-term stability, inter-rater agreement and convergent validity) of the Slovenian version of the RCADS and the RCADS-P in 754 primary and secondary school students and parents of 485 students. The short-term stability of anxiety and depressive symptoms in youth was assessed in a subsample of 117 children and adolescents. Results Confirmatory factor analysis showed an acceptable fit of the 6-factor model with CFI=0.92, TLI=0.92 and RMSEA=0.056 for RCADS and with CFI=0.93, TLI=0.92 and RMSEA=0.047 for RCADS-P. Cronbach's α and McDonald's ω ranged from 0.70 to 0.95 for the total scale and the six subscales. The subscales correlated significantly positively with the total Child Anxiety Life Interference Scale score. Conclusion The results affirm the good psychometric properties of the Slovenian versions of RCADS and RCADS-P within a school-based sample. There is a need in the future to examine psychometric properties in clinical samples and to provide normative data.

Longitudinal objective assessment of speech in Multiple Sclerosis

BackgroundRemote objective tests may supplement in-clinic examination to better inform treatment decisions. Previous cross-sectional studies presented objective speech metrics as potential markers of Multiple Sclerosis (MS) disease progression. ObjectiveTo examine the short-term stability and long-term sensitivity of speech metrics to MS progression. MethodsWe prospectively recorded speech from people with MS at baseline, six, twelve weeks, and at ten months or longer after baseline (1y+). Only people with a definite diagnosis of MS and without other potential causes of dysarthria were included. Speech tasks comprehended 1) a sustained vowel /a/, 2) saying the days of the week, 3) repeating the non-word pa-ta-ka multiple times as fast as possible, 4) reading the Grandfather Passage, and 5) telling a personal story. We selected speech metrics of interest according to their association with MS presence, correlation with general disability, and short-term metric stability in the absence of disease progression. Selected speech metrics were analysed for short- versus long-term changes in the whole MS cohort and in the clinically stable versus progression subgroups at 1y+. ResultsSixty-nine people with MS participated (76.8 % female, age mean 47.5 ± 11.1 SD, EDSS median 3.5, interquartile range 3.5). Twenty-six unique speech metrics satisfied the suitability criteria. On average, reading rate improved 3.5 % for all people with MS and 6.5 % for slow readers with MS from baseline to the six-week, driven by a reduction in pauses. At 1y+, participants showed a 3.1 % average reduction in vocalization time during the reading task, which was similar in the progression (n = 29) and non-progression (n = 40) groups and thus unrelated to disease progression. Both findings are in the opposite direction of what would be generally expected for deterioration in speech performance and might be attributable to familiarity and training effects. Other speech metrics showed either negligible change or a similar variability between short-term and long-term differences. ConclusionMost individual long-term changes were small and within short-term variability intervals, irrespective of clinical disease progression. Familiarity and practice effects might have blunted the measurement of change. The present lack of longitudinal sensitivity of speech in MS contradicts previous cross-sectional findings and requires further investigation.

The Langmuir-Blodgett trough (Langmuir film balance) can be used to understand the stabilizer concentrations in aqueous nano- and microsuspensions

Aqueous suspensions of poorly soluble, crystalline drug particles in the sub-micron range hold the ability to regulate the drug release for a defined period of time after e.g., intramuscular, or subcutaneous administration, working as an eminent formulation strategy for the preparation of long-acting injectables. Aqueous suspensions are typically prepared by top-down approaches, e.g., wet bead media milling or high-pressure homogenization, containing the active pharmaceutical compound and surfactants and/or polymers for stabilization purposes. Currently, the screening of proper stabilizers and adequate stabilizer concentration during formulation investigations is based on a trial-and-error approach with variations in combinations, concentrations, and/or ratios. To obtain a more efficient methodology during formulation screening, the present study investigated the correlation between the surface activity of two different surfactants, i.e., poloxamer 188 and polysorbate 20, by drop profile tensiometry and Langmuir trough monolayer, and the obtained sizes of cinnarizine particles as a tool to predict the optimal surfactant concentration to prepare physical stable nano- and microsuspensions. The obtained results demonstrated that the molecular area determined as the area per surfactant molecule measured in the Langmuir trough combined with the specific surface area of the prepared suspensions could be used to predict the suitable concentration of the surfactant based upon short-term stress stability data. The results further showed that higher concentrations of poloxamer 188 were necessary to stabilize the suspensions when compared to the needed concentration of polysorbate 20. In addition, it was observed that there was a need for a slightly higher surfactant concentration when the suspensions were milled with the smallest bead size of 0.5 mm instead of larger sizes of bead (0.8 and 1.0 mm), which could not be accounted for by differences in specific surface area.

The design of LLRF system for STCF storage ring

The Super Tau Charm Facility (STCF) is a new generation of high brightness electron–positron collider planned by China, designed to achieve a center of mass collision energy is 2–7[Formula: see text]GeV and a peak brightness is 0.5–[Formula: see text][Formula: see text]cm[Formula: see text]s[Formula: see text]. The digital low-level RF control system (LLRF), as the essential equipment of the storage ring RF system, is usually responsible for maintaining the stability of the cavity field. This paper presents the design scheme of LLRF for cavity in STCF storage ring, which mainly includes the hardware structure and software design of the system. We perform simulation analysis on the STCF RF system to evaluate the influence of delay and control parameters on the stability of the system and the influence of control parameters on the suppression of two kinds of noise. Desktop testing on the existing prototype demonstrates that the adopted direct-sampling architecture introduces less phase drift compared to the down-conversion architecture. Under the direct-sampling architecture, non-IQ demodulation offers better SNR and stability in both amplitude and phase. Specifically, direct-sampling in non-IQ mode achieves open-loop RMS short-term stability of 0.019% for amplitude and 0.021∘ for phase. Long-term stability in the closed-loop setting measures 0.027% for amplitude and 0.024∘ for phase.

Leveraging the Physicochemical Attributes of Biomimetic Hydrogel Nanocomposites in Stem Cell Differentiation.

The field of tissue engineering has witnessed significant advancements with the advent of hydrogel nanocomposites (HNC), emerging as a highly promising platform for regenerative medicine. HNCs provide a versatile platform that significantly enhances the differentiation of stem cells into specific cell lineages, making them highly suitable for tissue engineering applications. By incorporating nanoparticles, the mechanical properties of hydrogels, such as elasticity, porosity, and stiffness, are improved, addressing common challenges such as short-term stability, cytotoxicity, and scalability. These nanocomposites also exhibit enhanced biocompatibility and bioavailability, which are crucial to their effectiveness in clinical applications. Furthermore, HNCs are responsive to various triggers, allowing for precise control over their chemical properties, which is beneficial in creating 3D microenvironments, promoting wound healing, and enabling controlled drug delivery systems. This review provides a comprehensive overview of the production methods of HNCs and the factors influencing their physicochemical and biological properties, particularly in relation to stem cell differentiation and tissue repair. Additionally, it discusses the challenges in developing HNCs and highlights their potential to transform the field of regenerative medicine through improved mechanotransduction and controlled release systems.

Short-term and Long-term Stability of the Autism Diagnostic Observation Schedule (ADOS-2) Calibrated Comparison Scores (CCS) and Classification Scores in Youth with Down Syndrome or Fragile X Syndrome with Intellectual Disability

AbstractAutism diagnosis in individuals with fragile X syndrome (FXS) or Down syndrome (DS) with co-occurring intellectual disability is complex since clinicians often must consider other co-occurring behavioral features. Understanding how best to assess the features of autism in individuals with these conditions is crucial. In this study, we consider the short-term and long-term psychometric consistency of the Autism Diagnostic Observation Schedule-2 (ADOS-2) calibrated comparison scores (CCSs) and ASD classifications in individuals with FXS or DS. 76 individuals with DS (39 males; Mage = 15.27) and 90 individuals with FXS (71 males; Mage = 14.52 years) completed an assessment battery (ADOS-2, abbreviated IQ assessment and semi-structured language sample) at three timepoints (initial visit, short-term stability visit, long-term stability visit). All CCSs were found to have short-and long-term consistency for both groups, with lowest reliability scores for the repetitive behaviors (RRB) CCSs. Decreased reliability of RRB CCSs was found in the DS group than the FXS group. Variable short- and long-term ASD classifications were observed in both groups, with significantly higher variability in the DS group. Across groups, participants with variable classifications had lower ADOS-2 CCSs and higher language scores than those with stable ASD classifications. In the FXS group, those with variable classifications earned higher cognitive scores than did participants with stable ASD classifications. These findings highlight the high incidence of autism symptomatology in individuals with DS or FXS and co-occurring intellectual disability, while elucidating the short- and long-term variability of symptom expression in the context of structured observational tasks such as the ADOS-2.

Development of a new reference material for accurate measurements of lithium in Li-clays

Currently, there are no national and international certified reference materials (CRM) in lithium clays that can make reliable and traceable lithium measurements for the International System of Units (SI). Hence, it is necessary to have references to meet the needs in terms of mining and activities that involve the use of lithium to favor the economy derived from its multiple uses and associated benefits in the exploration, exploitation, and handling of lithium ore. In this study, a candidate for reference material (RM) of Li in clays was developed and certified based on the provisions of ISO 17034:2016 and ISO Guide 35:2017. Different mass sizes of the RM (0.05, 0.1, and 0.25 g) were used to evaluate homogeneity. An isochronous study (short-term stability) was carried out in the assessment of stability, influenced by the effects of transport at different temperatures (20, 40, and 50 °C) for a determined time of 6 weeks, in addition to a classic (long-term) study for 19 weeks. The sample was treated using microwave-assisted acid digestion and Li measurements were performed using the analytical technique of Flame Atomic Absorption Spectrometry (FAAS). The CRM is homogeneous for the sample mass sizes of 0.05 and 0.1 g, and the mass fraction of w(Li) was stable in the RM for temperatures of 20, 40, and 50 °C. The determined period of validity was 3 years.

Enhanced oxidation resistance and electrochemical performance of PEMFC gas diffusion layer through [EMIM][TFSI] ionic liquid coating

The performance and durability of Proton Exchange Membrane Fuel Cells (PEMFCs) are critically hindered by the oxidation susceptibility of graphite felt gas diffusion layers (GDLs). This study addresses this challenge by employing a protective coating of 1-Ethyl-3-methylimidazolium Bis(trifluoromethyl sulfonyl)imide ([EMIM][TFSI]) on the GDL through a dip-coating method, followed by thermal curing to ensure uniform distribution and strong adherence. Comprehensive characterization, including Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), and Fourier-Transform Infrared Spectroscopy (FTIR), confirmed the homogeneous coating, adhesion, and maintained porosity and gas diffusion properties of the GDL. The coated GDL exhibited a substantial increase in oxidation resistance, resulting in higher hydrophobicity with a contact angle of approximately 131°, compared to 96° for the uncoated GDL. Electrochemical analyses revealed that the [EMIM][TFSI]-coated GDL achieved a current density of 27 mA cm−2 at 0.925 V, surpassing the 19 mA cm−2 of the uncoated GDL at 0.91 V during cyclic voltammetry (CV) analysis. This study is limited by the short-term stability tests and the specific environmental conditions under which the experiments were conducted. Future work will focus on optimizing the coating process for varied environmental conditions and exploring the scalability of this technique for practical applications.

Oil unsaturation degree dictates emulsion stability through tuning interfacial behaviour of proteins

The unsaturated vegetable oil is commonly incorporated as protein-stabilized emulsion into fat-substituted emulsified meat products (FSEMP), whose quality is closely related with the emulsion stability. Here, we systematically investigated the effects of oil unsaturation degree (UD) on the interfacial properties (structural changes, adsorption dynamics, interfacial rheology, adsorption layer thickness) of proteins and thus the emulsion stability. The oleic acid and linolenic acid were mixed with dodecane as model oils. Three types of proteins were selected as model emulsifiers (fibrous myofibrillar protein, MP; globular whey protein, WP; random-coiled sodium caseinate, SC). The proteins diffused slower to the higher UD interface, resulting in a lower interfacial pressure. This led to a larger droplet size of the higher UD oil emulsion upon emulsification. However, the proteins penetrated and rearranged faster at the higher UD interface ascribed to a more extensive structural unfolding, enabling the formation of stiffer and thicker adsorption layers. This contributed to a stronger short-term stability of MP- and WP-stabilized higher UD oil emulsion; while for the random-coiled SC, the higher UD oil emulsion was less short-term stable, which was primarily determined by the initial (larger) droplet size but not the interfacial layer properties. The stiffer layer at the higher UD interface was on the other hand less stretchable, which tended to yield when subjected to higher strain. This probably accounted for the weaker long-term stability of the higher UD oil emulsion, regardless of protein types. These results highlighted that the oil UD should be elaborately considered for the rational formulation of FSEMP.

Missing data recovery based on temporal smoothness and time-varying similarity for wireless sensor network

Wireless Sensor Networks (WSN) play a vital role in the Internet of Things (IoT) and show great potential in monitoring applications. However, due to harsh environmental conditions and unreliable communication links, WSN often encounter partial data loss during data collection, which inevitably affects the quality of service. To address this challenge, researchers have employed matrix completion techniques to recover missing data by exploiting the low-rank features in the data, but its accuracy is not satisfactory. This paper argues that the spatiotemporal characteristics of the data underlie its low-rank nature, enabling a more accurate capture of the intrinsic patterns within the data. Drawing on this insight, we propose a missing data recovery algorithm based on Temporal Smoothness and Time-Varying Similarity (TSTVS). Unlike traditional low-rank methods, the TSTVS algorithm directly utilizes the structural features of data in the spatiotemporal domain to establish a missing data completion model. Subsequently, the model is converted into an unconstrained optimization problem using the penalty function method, and the gradient descent method is applied to solve it, reconstructing the complete data matrix. Finally, simulation experiments were conducted on three real-world monitoring datasets, comparing the TSTVS with three low-rank methods, Efficient Data Collection Approach (EDCA), Matrix factorization with Smoothness constraints (MFS) and Data Recovery Based on Low Rank and Short-Term Stability(DRLRSS). The experimental results indicate that the proposed TSTVS algorithm consistently outperforms the three low-rank based algorithms in terms of recovery accuracy across different datasets and missing rate scenarios.

Short-term voltage stability analysis in power systems: A voltage solvability indicator

This paper presents an analytical study for short-term voltage stability based on a novel indicator. First, it is shown that the reduced Jacobian matrix of network equations can be transformed to obtain an approximately symmetric matrix which is usually positive definite when the system under study is stable. The minimum eigenvalue of the matrix is suggested as a short-term Voltage Solvability Indicator (VSI). Then, properties of the reduced conductive matrix and susceptance matrix which have significant impacts on VSI are examined. The focus of the study is power systems with multiple constant power injections, while VSI can also be applied to analyze the impact of generic power system models. It is shown that as the penetration level of constant power injections increases, VSI decreases and the system becomes more vulnerable to voltage collapse. Finally, the relationship between the eigenvalues of the reduced Jacobian matrix and the structure-preserving Jacobian matrix is established. As a result, the suggested VSI can be efficiently computed by exploring the sparsity of structure-preserving Jacobian matrix of network equations. Case studies of several test systems including a simplified 575-machine 8117-bus East China power system are reported, demonstrating the effectiveness and practicability of the proposed method.

Deferasirox nanosuspension loaded dissolving microneedles for ocular drug delivery

Deferasirox (DFS) is an oral iron chelator that is employed in retinal ailments as a neuroprotectant against retinal injury and thus has utility in treating disorders such as excitoneurotoxicity and age-related macular degeneration (AMD). However, the conventional oral route of administration can present several disadvantages, e.g., the need for more frequent dosing and the first-pass effect. Microneedles (MNs) are minimally invasive systems that can be employed for intrascleral drug delivery without pain and can advantageously replace intravitreal injections therapy (IVT) as well as conventional oral routes of delivery for DFS. In this study, DFS was formulated into a nanosuspension (NS) through wet media milling employing PVA as a stabilizer, which was successfully loaded into polymeric dissolving MNs. DFS exhibited a 4-fold increase in solubility in DFS-NS compared to that of pure DFS. Moreover, the DFS-NSs exhibited excellent short-term stability and enhanced thermal stability, as confirmed through thermogravimetric analysis (TGA) studies. The mechanical characterization of the DFS-NS loaded ocular microneedles (DFS-NS-OcMNs), revealed that the system was sufficiently strong for effective scleral penetration. Optical coherence tomography (OCT) images confirmed the insertion of 81.23 ± 7.35 % of the total height of the MN arrays into full-thickness porcine sclera. Scleral deposition studies revealed 64 % drug deposition after just 5 min of insertion from DFS-NS-loaded ocular microneedles (OcMNs), which was almost 5 times greater than the deposition from pure DFS-OcMNs. Furthermore, both DFS and DFS-NS-OcMN exhibited remarkable cell viability when evaluated on human retinal pigment (ARPE) cells, suggesting their safety and appropriateness for use in the human eye. Therefore, loading DFS-NS into novel MN devices is a promising technique for effectively delivering DFS to the posterior segment of the eye in a minimally invasive manner.

A novel optical orthogonality control approach based on noise propagation and its application in spin-exchange relaxation-free co-magnetometers

This paper presents a non-destructive optical orthogonality control method based on adaptive gradient descent for spin-exchange relaxation-free co-magnetometers (SERFCM). The spin-exchange optical pumping technique serves as the foundation of SERFCM measurement. Analyzing the impact of pump power fluctuation on the transverse polarizability of alkali metal atoms in the presence of non-orthogonal beams, considering stochastic noise propagation, is addressed. Subsequently, an optical orthogonal calibration scheme is proposed. Leveraging the proposed orthogonal calibration scheme, an adaptive gradient descent method based on the reference model is formulated, and simulation validates its effectiveness in addressing the rapid online optimization control of SERFCM optical quadrature. Experimental results indicate that the proposed optical orthogonal calibration scheme offers higher accuracy, with the proposed optical orthogonal control algorithm saving 34% of the time compared to the traditional algorithm. Finally, the stability of SERFCM is evaluated using Allan variance, demonstrating that the adjusted SERFCM enhances short-term stability by 84% at around 1s and long-term stability by 639% at around 300s.

Monetary policy impact on sustainability: Analyzing interest rates and corporate carbon emissions

This study aims to investigate the impact of monetary policy on firms’ carbon emissions. The primary focus is on the effect of increasing interest rates on the carbon footprint of companies, both prior to and following the implementation of the Paris Agreement in 2015. The results show that there is a positive relationship between interest rates and carbon emissions indicating that in the face of increasing interest rates, companies are more likely to choose short-term financial stability above long-term sustainability objectives. This positive relationship is less prevalent following the Paris Agreement suggesting that policymakers should continue to strengthen global climate initiatives as a pressure for companies to invest in green activities. Additional evidence suggests that the impact of interest rates on carbon emissions is particularly noticeable in situations characterized by elevated levels of economic and policy uncertainty, weak corporate governance quality, and poor investor protection. These results are robust to endogeneity concerns, alternative measures of interest rates, carbon emission, and alternative samples.

Complex non-linear relationship between conventional and green bonds: Insights amidst COVID-19 and the RU–UA conflict

In times of crisis, such as global pandemics or conflicts, investors’ preference between green and conventional bonds may lean towards the latter due to increased risk aversion and a focus on short-term stability. However, some investors motivated by increased awareness of sustainability issues may maintain or increase their allocation to green bonds, seeing them as an opportunity for long-term resilience and sustainable investing. We use multifractal detrended cross-correlation analysis, wavelet coherence, and copula-based dependence analysis to examine the complex relationship between the S&P Green Bond Index and the S&P 500 Bond Index. The results indicate the presence of multifractal cross-correlations, the strength of which is most pronounced in times of crisis, especially in the post-COVID-19 period. The wavelet-based analysis also detects the COVID-19 break and shows significant interdependence at all frequency levels after the RU–UA conflict. The copula-based correlation values exhibit a distinct oscillating pattern over time, characterized by an initial break coinciding with the impact of COVID-19. In light of these findings on the impact of COVID-19 and the RU–UA conflict, we have included the Geopolitical Risk Index in our analysis to better understand how geopolitical tensions and conflicts influence the observed interdependence and to gain insight into how changes in the global risk environment affect both bond market dynamics. Overall, the results of this study provide insights into the interconnectedness between conventional and green bond markets and highlight potential spillover effects and systemic risks in an increasingly complex financial landscape.