Slope Of Response Research Articles

Do more with less? Impact of personalized very low doses of amlodipine in the PERSONAL-CovidBP trial

Abstract Introduction The Personal-CovidBP study1 tested remote patient use of a drug-device combination of a smartphone application (App) to record blood pressure (BP), novel personalized milligram-by-milligram drug (amlodipine) dose, and relevant side effects daily during the COVID-19 pandemic. Purpose In supplementary data analyses, we examined the effect of using small doses (1 mg) and small increments (1-2 mg) of amlodipine on the BP response and side effects. Methods In this community-based trial with remote monitoring and remote medical management from the investigational site, hypertensive participants aged 18 years + with poor BP control (prior 7 day mean of 135 mmHg systolic BP or above and/or 85 mmHg diastolic BP and above) were enrolled to intervention with open label dose titration over 14 weeks, allowing personalized dosing of liquid amlodipine (1–2 mg steps from 1–10 mg daily). Results 205 patients were enrolled into the intervention group between October 2020 and July 2021. Average BP in intervention fell from 141/87 to 131/81 (difference −10/6 p < 0.001). Even low doses or small increments: 1 or 2 mg amlodipine or 5 mg to 6 mg, produced meaningful BP responses. Here we report that the addition of amlodipine during the study reduced blood pressure regardless of being amlodipine naive at baseline (n=141), or receiving amlodipine 2.5mg or 5mg at baseline (n=62). The response slopes were comparable, and mean reductions in SBP were consistent across groups: -11.7 (95% CI: -12.9 to -10.6); -9.4 (-11.1 to -7.7); respectively (Figure 1). For the amlodipine naive, the majority (76%) achieved BP control at low doses (<1 to 3mg) with occurrence of side effects increasing with dose (Figure 2). Conclusions Our real-world remote care study demonstrated that very low doses of amlodipine as little as 1 mg were effective and for 1mg-3mg gained BP control in the majority and were associated with fewer side effects which is consistent with previous meta-analyses.2 Personalized treatment titration was effective even at very low doses and also regardless of whether amlodipine naive or not at baseline.Changes in SBP- baseline amlodipine useAmlodipine dose at control vs oedema

Model-Informed Approach to Recommend Burosumab Dosing Regimens for Pediatric and Adult Patients With the Ultrarare Disease Tumor-Induced Osteomalacia.

Burosumab is approved for the treatment of hypophosphatemia in persistent tumor-induced osteomalacia. This work exemplifies a model-informed drug development approach that evaluated burosumab pharmacokinetics and pharmacokinetic/pharmacodynamics in the ultrarare tumor-induced osteomalacia population to support adult and pediatric dosing. Data from tumor-induced osteomalacia participants were combined with data from X-linked hypophosphatemia to understand pharmacokinetic and pharmacokinetic/pharmacodynamic characteristics and covariates specific to tumor-induced osteomalacia. Pharmacokinetic and pharmacokinetic/pharmacodynamic simulations were performed using final models to support dosing recommendations for adults and extrapolation to pediatric patients. Burosumab pharmacokinetics were described using a one-compartment model with first-order absorption and body weight as a significant covariate. Pharmacokinetic/pharmacodynamic relationships were described using a sigmoidal Emax model with significant covariates of baseline fibroblast growth factor 23 on baseline fasting serum phosphate and potency of burosumab response and tumor-induced osteomalacia disease state resulting in a steep slope of response; however, the covariates are not clinically meaningful. Simulations demonstrated that, in pediatric patients, starting doses of burosumab 0.3 and 0.4 mg/kg every 2 weeks at steady state would achieve normal serum phosphate levels in ≥ 30% of patients with relatively low risk of hyperphosphatemia (< 3%). In adults, burosumab 0.3 and 0.5 mg/kg every 4 weeks achieves similar percentages of responders and a relative low risk of hyperphosphatemia (< 7%). Serum phosphate titration-based burosumab dosing increased the probability of achieving normal serum phosphate levels. The models supported a model-informed drug development approach for global approvals of titration-based burosumab dosing, guided by monitoring fasting serum phosphate levels.

Laboratory Model Tests on the Deformation and Failure of Terraced Loess Slopes Induced by Extreme Rainfall

Heavy rainfall is the main factor inducing the failure of loess slopes. However, the failure mechanism and mode of terraced loess slopes under heavy rainfall have not been well investigated and understood. This paper presents the experimental study on the deformation and failure of terraced loess slopes with different gradients under extreme rainfall conditions. The deformation and failure processes of the slope and the migration of the wetting front within the slope during rainfall were captured by the digital cameras installed on the top and side of the test box. In addition, the mechanical and hydrological responses of the slope, including earth pressure, water content, pore water pressure, and matric suction, were monitored and analyzed under rainfall infiltration and erosion. The experimental study shows that the deformation and failure of terraced loess slopes under heavy rainfall conditions exhibit the characteristic of progressive erosion damage. In general, the steeper the slope, the more severe the deformation and failure, and the shorter the time required for erosion failure. The data obtained from sensors embedded in the slope can reflect the mechanical and hydraulic characteristics of the slope in response to rainfall. The earth pressure and pore water pressure in the slope exhibit a fluctuating pattern with continued rainfall. The failure mode of terraced loess slopes under extreme rainfall can be summarized into five stages: erosion of slope surface and formation of small gullies and cracks, expansion of gullies and cracks along the slope surface, widening and deepening of gullies, local collapse and flow-slip of the slope, and large-scale collapse of the slope. The findings can provide preliminary data references for researchers to better understand the failure characteristics of terraced loess slopes under extreme rainfall and to further validate the results of numerical simulations and analytical solutions.

Evaluating Heat Stress Effects on Growth in Tunisian Local Kids: Enhancing Breeding Strategies for Arid Environments.

This study evaluates the impact of thermal load on the weights of Tunisian local kids using 24 models with cubic and quadratic Legendre polynomials, based on daily temperatures (Tmin, Tmax, and Tavg) on the day of weight recording and averaged over 7, 14, and 21 days before weighing. The deviance information criterion (DIC) consistently shows that cubic polynomial models offer a better fit than quadratic models, highlighting their superior accuracy in studying the effects of thermal load on kid weights. The models with the best fit utilized average or maximum temperatures over 14 or 21 days. The patterns of response were similar across the temperature variables and periods, showing a stable weight response at lower temperatures (thermoneutral region) followed by a decline as the temperatures increased. The weight loss was -125 g/°C beyond the moderate heat stress threshold (Tavg21 = 17.7 °C) and -450 g/°C beyond the severe heat stress threshold (Tavg21 = 25.3 °C) for Tavg21. The heat stress thresholds for moderate heat stress (HS1) were 8.6 °C for Tmin14, 27.4 °C for Tmax14, and 18.6 °C for Tavg14; moreover, for acute heat stress (HS2), they were 17.2 °C for Tmin14, 32.4 °C for Tmax14, and 25.5 °C for Tavg14. High variability in individual responses was observed, with differences in the slope of response ranging from 2.0 kg/°C for moderate heat stress to around 3.0 kg/°C for severe heat stress for Tavg. The correlations between the weights under different temperatures were low, indicating that rankings based on weight could change with varying heat conditions. The animals with larger weight levels generally demonstrated better heat tolerance, and those with good heat tolerance under moderate conditions were also likely to have good tolerance under severe conditions.

An All-Solid-State Ti/RuOx pH Electrode Prepared Based on the Thermal Oxidation Method.

The development of all-solid-state precise pH electrodes holds significant importance in various fields, particularly in marine scientific research. To achieve this goal, we proposed a novel fabrication technique for an all-solid-state ruthenium oxide (Ti/RuOx) pH electrode. We thin-coated the RuCl3 precursor solution on a titanium wire substrate using a heat gun repeatedly and then calcined it in a mixture of Li2CO3 and Na2O2 at 400 °C to obtain a ruthenium oxide (RuOx) film. This RuOx film was subjected to acid treatment with dilute nitric acid, and a polytetrafluoroethylene heat shrink tube was wrapped around the non-RuOx film area. Finally, the RuOx film was fully immersed in a pH 4.00 buffer solution, finalizing the electrode preparation. The RuOx film exhibits a dense and regular conical morphology. The Ti/RuOx electrode demonstrates a good near-Nernstian response slope (e.g., -59.04 mV/pH at 25 °C), high linearity (e.g., R2 = 0.9999), rapid response (<1 s), low hysteresis (<3 mV), excellent reversibility, and good repeatability in the pH range of 2.00-10.00. After full hydration, the Ti/RuOx electrode shows a potential drift of 8.5 mV and a drift rate of approximately 0.27 mV/day over a period of 25 days, indicating good long-term stability. Furthermore, the Ti/RuOx electrode exhibits robust resistance against interference from various ions and low-concentration redox substances, ensuring a long storage life (at least 280 days), and high measurement accuracy (e.g., ± 0.02 pH units) for diverse water samples, including seawater, freshwater, and tap water. This study has evaluated the potential of the Ti/RuOx electrode as a reliable and accurate tool for pH measurements in marine scientific applications.

Association between exposure to air pollution and increased ischaemic stroke incidence: a retrospective population-based cohort study (EP-PARTICLES study)

Abstract Aims Short-term effects of Polish smog, particularly benzo(alpha)pyrene [B(a)P], are unclear. We aimed to examine the association between short-term exposure to air pollution and ischaemic stroke (IS) incidence. Methods and results We conducted a retrospective population-based cohort study including an EP-PARTICLES cohort of 8 million inhabitants in the years 2011–20 (80 million person-years of observation). Individual clinical data on emergency hospitalizations due to IS (ICD-10: I63.X) was analysed. We used quasi-Poisson models to examine municipality-specific associations between air pollutants and IS, considering various covariates. We recorded 146 262 cases of IS with a dominance of females (51.8%) and people over 65 years old (77.6%). In the overall population, exposure to PM2.5, NO2, B(a)P, and SO2 increased the risk of IS onset on the day of exposure by 2.4, 1, 0.8, and 0.6%, respectively. Age and sex were modifying variables for PM2.5, NO2, and B(a)P exposure with more pronounced effects in non-elderly individuals and women (all Pinteraction &amp;lt; 0.001). Residents of regions with high tobacco and alcohol consumption were more sensitive to the effects of PM2.5 and SO2. The slopes of response–effect curves were non-linear and steeper at lower concentrations. Conclusion Exposure to air pollution may be associated with higher IS incidence, particularly posing a higher risk to non-elderly women. Harmful lifestyle habits might exacerbate its impact. Exposure to even low levels of air pollutants had negative effects. Registration The study was registered at ClinicalTrials.gov (NCT05198492).

A cathodically polarized PANI-based lead ion-selective electrode: achieving high stability with antibiofouling capabilities.

Solid-state contact ion-selective electrodes (SC-ISEs) are an efficacious means of monitoring heavy metal contamination. Instability of the electrode potential is a key factor limiting their development, with biofouling in real water samples posing a significant challenge to maintaining stability. Therefore, addressing biofouling is crucial for optimizing solid-state ion-selective electrodes. In this work, high stability and antibiofouling capability in a solid-state contact lead ion-selective electrode (SC-Pb2+-ISE) based on polyaniline (PANI) was achieved through cathodic polarization. Specifically, PANI played a dual role in the ion-selective membrane (ISM) as an ion-to-electron transducer and antifouling agent. Given the excellent electrochemical performance of PANI, the prepared electrode (GC/PANI-Pb2+-ISM) demonstrated a remarkable antibiofouling efficiency of 98.2% under a cathodic polarization of -0.2V. Furthermore, a standard deviation of standard potential (Eθ) as low as ± 0.5mV was realized successfully. The excellent chrono-potentiometric stability of 17.0 ± 2.9μV/s was also demonstrated. The electrode maintained a Nernstian response slope of 30.7 ± 0.2 (R2 = 0.998) after applying a cathode potential (-0.2V) for 30min. The developed GC/PANI-Pb2+-ISM electrode is suitable for practical applications in real environmental water sample monitoring.

Characteristics of surface ozone pollution and its correlations with meteorological factors: the case of Xiangtan.

Based on ozone (O3) monitoring data for Xiangtan and meteorological observation data for 2020-2022, we examined ozone pollution characteristics and the effects of meteorological factors on daily maximum 8-h average ozone (O3-8h) concentrations in Xiangtan. Thus, we observed significant increases as well as notable seasonal variations in O3-8h concentrations in Xiangtan during the period considered. The ozone and temperature change response slope (KO3-T) indicated that local emissions had no significant effect on O3-8h generation. Further, average O3-8h concentration and maximum temperature (Tmax) values showed a polynomial distribution. Specifically, at Tmax < 27 °C, it increased almost linearly with increasing temperature, and at Tmax between 27 and 37 °C, it showed an upward curvilinear trend as temperature increased, but at a much lower rate. Then, at Tmax > 37 °C, it decreased with increasing temperature. With respect to relative humidity (RH), the average O3-8h concentration primarily exceeded the standard value when RH varied in the range of 45-65%, which is the key humidity range for O3 pollution, and the inflection point for the correlation curve between O3-8h concentration and RH appeared at ~55%. Furthermore, at wind speeds (WSs) below 1.5 m∙s-1, O3-8h concentration increased rapidly, and at WSs in the 1.5-2 m∙s-1 range, it increased at a much faster rate. However, at WSs > 2 m∙s-1, it decreased slowly with increasing WS. O3-8h concentration also showed the tendency to exceed the standard value when the dominant wind directions in Xiangtan were easterly or southeasterly.

Experimental Approaches to Iron Determination in Potentiometric Sensors Using (2-2-(4-Dinitrophenyl) Hydrazono) Methylphenol

The study presents a PVC membrane-based potentiometric sensor for iron (III) detection, demonstrating impressive selectivity in Fe(III) ion-selective electrodes (ISE). The sensor achieves a detection limit of 4.0×10−7 M and a Nernstian response slope of 19.4 mV per decade change within a concentration range of 7.4×10−7 to 1×10−1 M. Operating efficiently within the pH range of 3.6–10, the sensor maintains its potential divergence-free utility for at least eight weeks and has a rapid response time of approximately twenty seconds. The sensor’s selectivity for Fe3+ ions makes it a robust tool for specific Fe(III) ion detection. The sensor’s reliability and longevity make it a valuable tool for continuous monitoring applications, providing accurate and timely information on the presence of iron ions in diverse settings.

A highly stable membrane-free potentiometric pH sensor with nickel cobalt sulfide as the solid contact layer and ion recognition

In this work, a new NiCo2S4 based H+ ion-selective electrode (ISE) without a polymer membrane was proposed and used to rapidly monitor the pH values of wetland soils in the Yellow River Delta in China. This NiCo2S4-based potentiometric pH sensor without an ion-selective membrane (ISM) exhibited a near-Nernstian response slope (50.9 ± 0.4 mV/dec) and good sensitivity. Furthermore, the developed pH sensors using NiCo2S4 as a solid contact (SC) layer present good reproducibility and the standard deviation of Eo is only 0.75 mV (n = 6). The water layer at the SC/ISM interface of the NiCo2S4-based membrane-free potentiometric pH sensor vanished, thus yielding excellent long-term potential stability (8.6 ± 0.4 μV/h over 264 h). This pH sensor offers a new design strategy for the construction of miniaturized highly stable ISEs without ISM.

Threat sensitivity in emotion dynamics: Negativity effects and sex differences

Evolutionary theorizing has given rise to the idea that responding to any particular threat may be more mandatory than responding to any particular reward. The present three experiments (total N = 375) sought to provide support for this perspective in an emotion dynamics task in which participants continuously rated their affective state in response to appetitive (reward-related) versus aversive (threat-related) images. Even when equating images for arousal and extremity, several negativity effects (e.g., steeper reactivity slopes in response to aversive images) were found. These negativity effects can serve as an experimental model of threat sensitivity, which should predispose some individuals, more than others, to symptoms related to fear and anxiety. This point was made with respect to sex differences, given that women (relative to men) are diagnosed with anxiety disorders at higher rates. Sex differences were pronounced and extensions of this work, both basic and applied, are proposed.

Interplay of Adolescents' and Parents' Mindsets of Socioeconomic Status on Adolescents' Stress-Related Outcomes.

The reciprocity and variation of values and beliefs are dynamic features of the parent-child relationship. Parents and adolescents may hold congruent or incongruent views regarding the malleability of socioeconomic status (mindset of SES), potentially influencing adolescents' psychological and physiological stress outcomes, as reflected in stress perceptions and the hypothalamic-pituitary-adrenal (HPA) axis functioning. The current study investigated how patterns of parent-adolescent congruence and incongruence in mindset of SES were associated with adolescents' perceived stress and diurnal cortisol patterns four months later. A total of 253 adolescents (Mage = 12.60, 46.2% girls) and their parents (Mage = 40.09 years, 59.5% mothers) participated in this study. Polynomial regression analyses and response surface analyses showed that adolescents perceived lower levels of stress when they themselves or their parents reported a stronger growth mindset of SES. Additionally, adolescents with a stronger growth mindset of SES also exhibited a steeper diurnal cortisol slope. Moreover, parents' mindset significantly interacted with adolescents' mindset to influence adolescents' diurnal cortisol patterns such that when adolescents hold weaker growth mindset of SES, those with higher parental growth mindsets had significantly higher cortisol awakening response and steeper diurnal cortisol slope. Furthermore, adolescents who showed incongruence with their parents but had averagely stronger growth mindsets of SES reported a significantly steeper diurnal cortisol slope than those who had averagely weaker growth mindsets with their parents. The findings point to the beneficial impacts of the growth mindset of SES on stress-related outcomes among adolescents, as well as the significance of considering both parents' and adolescents' mindsets when exploring these associations.

Predicting symptom response and quality of life to the low FODMAP diet in irritable bowel syndrome: a 6-month longitudinal study

The low fermentable oligosaccharide, disaccharide, monosaccharide and polyol (FODMAP) diet is recommended as a first line therapeutic management strategy for irritable bowel syndrome (IBS)(1). The low FODMAP diet is supported by meta-analytical evidence(2), and demonstrates acceptability and effectiveness for improving symptoms and quality of life (QoL) in 50-75% of individuals with IBS. However, a subset of individuals (25-50%) do not respond to the diet(3). The identification of individual-level predictors of treatment response across all three phases of the low FODMAP diet is currently lacking. The study aims were to assess psychological predictors of symptom and QoL response to the low FODMAP diet in patients with IBS. Adults with IBS underwent a three-phase low FODMAP diet, guided by individualised dietetic education. Predictor variables included levels of depressive, anxiety, and extraintestinal somatic symptoms, stress, treatment beliefs and expectations, behavioural avoidance, and illness perceptions. Symptom severity and QoL were the main outcomes. Questionnaires assessing psychological predictors, symptoms and QoL were administered at five points: pre-dietitian (week 0), post-dietitian, end of elimination (week 5), end of reintroduction (week 13), and end of personalisation (week 25) phases. Latent class growth analysis was used to identify classes of response trajectories for symptoms. Linear mixed models were used to test the effect of baseline psychological scores on symptoms and QoL over time. Cross lagged panel models determined the directional predictive relationship between psychological predictors and symptom severity. 112 participants (89% F) median age 30 ± 17 years were included. There were three classes of symptom response trajectories, including ‘non-improvers’ (21.3% of participants) with high initial symptom severity and minimal improvement, ‘improvers’ (22.5% of participants) with low initial symptom severity and significant improvement, and an ‘intermediate’ group (56.2% of participants) with moderate initial symptom severity and significant improvement. Higher treatment beliefs predicted a stronger initial symptom response (effect on linear slope p = 0.036). Lower gut-specific anxiety, as well as higher levels of personal and treatment control at baseline predicted a stronger reduction in IBS symptom severity and improved QoL from week 0 to week 25. Participants with higher levels of baseline psychological symptoms and negative illness perceptions (i.e., lower emotional representations) predicted a stronger initial and later QoL response (effect on linear (p = 0.006) and quadratic (p = 0.049) slopes). Increased cyclical time beliefs predicted poorer initial and later QoL response (effect on linear (p = 0.015) and quadratic (p = 0.029) slopes). Individuals experiencing lower to mid-range symptom severity at baseline had greater improvement with the low FODMAP diet. Lower anxiety, positive illness views and higher treatment beliefs predict better QoL and symptom response. Personalised strategies are crucial for optimising low FODMAP diet effectiveness in IBS.

Moving stimuli enhance beat timing and sensorimotor coupling in vision.

Vision has long been known for its inefficiency in beat perception and synchronization. However, this has been challenged by the finding that moving stimuli (bouncing ball or moving bar) can significantly improve visual beat synchronization. The present study examined two possible mechanisms for this phenomenon: visual motion facilitates temporal processing or promotes sensorimotor coupling. Instead of a single visual object (such as a ball or bar), random-dot kinematograms (RDKs) were used to construct visual motion sequences to avoid confounding factors, such as changes in trajectory and velocity. Experiment 1 showed that RDKs improved beat-timing discrimination compared with visual flashes, but auditory tones were still superior to RDKs. In Experiment 2, synchronized movements improved auditory-tone beat timing but impaired visual-flash beat timing, with no effect on RDK beat timing. Experiment 3 indicated that the regression slope of the phase correction response in RDKs was higher than that in visual flashes but still lower than that in auditory tones. The results showed that moving stimuli enhances both temporal processing (Experiment 1) and sensorimotor coupling (Experiments 2 and 3) in vision, but to a lesser degree, with audition retaining an advantage. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Serial Diurnal Salivary Cortisol Profiles in 667 Pregnant Women-Association With Cardiometabolic Complications.

Maternal obesity, hypertensive pregnancy disorders, and gestational diabetes (GDM) are linked to an increased risk of negative offspring health outcomes. This association may be mediated by maternal hypothalamic-pituitary-adrenal axis (HPA axis) activity, resulting in elevated maternal cortisol levels and fetal exposure, but evidence remains scarce. We (1) examined maternal diurnal cortisol profiles longitudinally across gestation, and (2) explored associations with maternal cardiometabolic complications. Women in the InTraUterine sampling in early pregnancy (ITU) study (n = 667) provided 7 salivary cortisol samples from awakening to bedtime up to 3 times during pregnancy (median gestational week 19.3, 25.7, and 38.1; n = 9356 samples). Changes in cortisol awakening response (CAR) and diurnal slope (indicative of HPA axis activity) and their associations with maternal body mass index (BMI), hypertensive pregnancy disorders and GDM were examined using linear mixed models. The CAR declined in 60% to 67% of women, and the diurnal slope attenuated from early to late pregnancy (b = 0.006; P = .001). Higher BMI was associated with less decline in CAR (b = 0.031; P = .0004) and less attenuation in diurnal slope from early to late pregnancy (b = -0.001; P = .006). Hypertensive pregnancy disorders and GDM were not significantly associated with diurnal cortisol profiles. The attenuation in CAR and diurnal slope support HPA axis hyporesponsivity during pregnancy. Less attenuation of both markers in women with a higher BMI may indicate reduced adaption of the HPA axis to pregnancy, presenting a mechanistic link to offspring health outcomes.

Do Economic and Social Satisfaction Matter Equally in Sustainable Business? Hotel Membership Types and Sales Promotions

Customer responses to economic and social satisfaction are important in business-to-business transactions; however, these responses can vary when customer segments and sales promotions are combined. This study investigates the roles of two satisfaction types by demonstrating three-way interactions with two moderators: memberships and promotion levels. Using survey data on paid hotel memberships in Korea, this study focuses on the moderated moderation effects of hotel membership type and sales promotions. The authors find that sales promotions positively affect members’ behavioral intentions when they are economically or socially satisfied, regardless of the membership type. In particular, when social satisfaction is positive, the impact of sales promotions on paid membership renewal intentions increases dramatically regardless of the membership type. Meanwhile, lower-tiered members respond more positively to price discounts, increasing their paid membership renewal intentions. In contrast, premium members prefer coupons over price discounts. However, the slope of customer responses is steeper for social satisfaction than economic satisfaction, highlighting that the impact of sales promotions differs by membership type.

Fabrication of flexible paper-based conducting molecularly imprinted polymer as analytical devices: Electrochemically assisted solid phase microextraction and selective flexible sensor for determination of naproxen

An electrochemical method is presented for the preparation of paper-based conductive molecular imprinted polymer (CMIP) film as a recognition element of a sensor and a selective absorber in separation methods. The paper became conductive by chemically incorporating polypyrrole (PPy) doped with anion dopant. The effects of the anion dopant and oxidant type on the conductivity of the modified paper were studied. Afterward, a CMIP film based on PPy and an anionic drug as a template was electrochemically synthesized on conductive paper surface, which was then utilized as a selective sorbent for electrochemically assisted solid phase microextraction (EC-SPME) and a recognition element in fabricating flexible drug-selective sensor. Factors affecting the performance of the paper-based EC-SPME device were studied in naproxen (NAP) analysis. All quantitative analytical parameters in the EC-SPME device were obtained by UV–vis absorption spectroscopy. Under the optimal conditions, linearity was achieved within the range of 2.0 × 10−7–2.0 × 10−5 mol/L with determination coefficient (R2 = 0.99) and the limit of detection (LOD) was 0.6 × 10−7mol/L. Moreover, a fabricated paper-based NAP-selective sensor, showed Nernstian response slopes of −61.6 ± 0.5 mV decade−1 over the linear range of 4.0 × 10−7–1.0 × 10−2 mol/L and LOD was 2.0 × 10−7 mol/L. The applicability and efficiency of the paper-based analytical devices were investigated for NAP determination as a model drug in human serum samples. The recoveries were obtained in the range of 90.0–103.0 %. Accordingly, paper-based CMIPs were found to be a novel fabrication method for efficient, selective, flexible and cost-effective material for analytical devices.

ИМПЕДАНСНЫЙ АНАЛИЗ ПРОЦЕССОВ ПЕРЕНОСА ЗАРЯДА В СТРУКТУРЕ МЕТАЛЛ/ПОЛИМЕР/МЕТАЛЛ

The reaserch is devoted to the experimental study of charge transfer processes in thin films of an electroactive polymer from the class of polyarylene phthalides – poly (diphenylene phthalide). The method of impedance analysis of thin polymer films was used in this work. The material is quite well studied using other methods, such as thermally stimulated methods, optical spectroscopy, etc. However, frequency measurements were carried out mainly only in the field of determining capacitance-voltage characteristics. And since the polymer is electroactive, we should expect to identify features associated with charge transfer in the alternating field mode. In this regard, the work carried out an impedance analysis of thin films of poly (diphenylene phthalide) in the frequency range from 0.1 to 106 Hz. Typically, in impedance analysis, in addition to an ac field, a small DC bias voltage is applied to the metal/polymer/metal structure. This makes it possible to obtain data on surface polarization, charge carrier mobility, and the Maxwell-Wagner effect in the case of studying multilayer films. However, taking into account the electrical activity of the studied material, even impedance analysis in an alternating field, but with an effective voltage range from 0.1 to 10 V, made it possible to evaluate some of the electrophysical characteristics of the behavior of thin films. It was found that the slope of the impedance curve depends on the mechanism of transport of charge carriers in the polymer film. As the voltage increases from 0.1 to 10 V, an increase in the slope of the graph is observed. With an increase in the magnitude of the effective voltage, a transition occurs from the ohmic to the injection mechanism of transport of charge carriers limited by traps. When reaching 2 V, a mode of complete filling of the traps is observed, as a result of which an increase in voltage ceases to affect the slope of the frequency response. The dependence of the transition frequency fc on voltage has been plotted. This frequency corresponds to the transition from the predominance of the active to the reactive component of the impedance. Here, an exponential dependence on the magnitude of the applied voltage is observed, which also indicates the dependence of the mechanisms of transport of charge carriers in the polymer film on voltage (electric field).

UV-activated semiconductor gas sensor response measurement for formaldehyde detection

The gas sensing characteristics of ultraviolet light-emitting diodes (UV-LEDs)-activated semiconductor sensors were investigated to detect formaldehyde (HCHO) as a model volatile organic compound (VOC). As the major drawback of formaldehyde gas sensors is the low durability of the sensing material, efforts were made to establish a suitable metal oxide semiconductor and to enhance its stability throughout the sensing process. In2O3 nanoparticles (NPs) as the sensing material showed restructuring caused by exposure to different concentrations of formaldehyde in the presence of UV radiation when its morphology and structure were analyzed. UV radiation in the presence of formaldehyde was found to play a critical role in nanoparticles agglomeration, as well as its response inconsistency and instability.The novel method of measuring UV radiation elimination in the initial stages of the response curve was deemed effective for sensing layer preservation in this study. The scanning electron microscopy (SEM) results showed that this approach prevented any notable deformation in the nanoparticles’ shape and size and resulted in reproducible responses to various formaldehyde concentrations (10–50 ppm) in the steady-state and transient (5 min exposure) phases of the response curve. Hence, a short-time UV exposure has the potential to be applied in practical gas sensing applications in which the sensor can be automatically turned off a few minutes after any target gas detection. The gas sensor response slope in the transient phase of the response curve was found to be a very good indicator of target gas concentration and to obtain fast and consistent results while preserving the sensing material from restructuring. The findings of this study can be incorporated into the development of UV-LED-activated gas sensors where stable and fast response measurements of VOCs are required.

Paradoxical breathing during sleep is associated with increased sleep apnea and reduced ventilatory capacities in high-level spinal cord injury.

Sleep-disordered breathing is highly prevalent in individuals with high-level spinal cord injury. In addition, chest mechanics are known to be altered, leading to paradoxical breathing. Here we investigated the interaction between paradoxical breathing and sleep quality in these patients, and its association with measurements of respiratory function, hypercapnic ventilatory response and peak exercise ventilation. Home-based polysomnography was performed in 13 patients with spinal cord injury (C4 to T4) untreated for sleep-disordered breathing. We defined paradoxical breathing as counterphase between thoracic and abdominal movements during slow-wave and rapid eye movement sleep. Sleep quality, pulmonary function, hypercapnic ventilatory responses and peak exercise ventilation were compared between those with and without paradoxical breathing. Half of individuals presented with nocturnal paradoxical breathing. Despite similar age, body mass index, injury level, time since injury, and respiratory function, those with paradoxical breathing had higher apnea-hypopnea index (13 ± 8 versus 5 ± 3 events per hr) and average sleep heart rate (67 ± 12 versus 54 ± 4 bpm; p < 0.05). Moreover, paradoxical breathing was associated with lower hypercapnic ventilatory response (slope: 0.35 ± 0.17 versus 0.96 ± 0.38) and lower peak exercise ventilation (33 ± 4 versus 48 ± 12 L min-1; p < 0.05). Nocturnal respiratory muscle desynchronization could play a role in the pathophysiology of sleep apnea, and could relate to low ventilatory responses to both hypercapnia and exercise in high-level spinal cord injury. Polysomnography may be an important diagnostic tool for these patients for whom therapeutic approaches should be considered to treat this abnormality.