Unusual Peak Research Articles

Alkali rare earth double phosphates: Promising new high temperature scintillators

Alkali rare earth double phosphates were investigated for their X-ray induced scintillation. Double phosphates with stoichiometry A3Ln(PO4)2 (A = K or Rb, Ln = Eu or Tb) were synthesized via a eutectic molten salt flux yielding high quality single crystals. The systematic variation of the alkali and rare earth elements in the structure allowed for insights into the effects of the chemical composition on the scintillation output. The radioluminescence of these compositions under X-ray excitation is reported with a discussion of the variance of their luminosity as a function of both the constituent alkali and lanthanide elements. The relative luminosity of Rb3Tb(PO4)2 surpasses BGO by 30 %. The dependance of the scintillation on temperature is also investigated, including an unusual peak intensity increase for higher temperatures that can reach 1.4x of its value at room temperature for Rb3Tb(PO4)2 at 255 °C, and 2.1x for K3Tb(PO4)2 at 495 °C.

Characterisation of sealed radioactive source for nuclear forensic purposes

Characterisation of sealed radioactive source for nuclear forensic purposes

Dramatic Rebrightening of the Type-changing Stripped-envelope Supernova SN 2023aew

Multipeaked supernovae with precursors, dramatic light-curve rebrightenings, and spectral transformation are rare, but are being discovered in increasing numbers by modern night-sky transient surveys like the Zwicky Transient Facility. Here, we present the observations and analysis of SN 2023aew, which showed a dramatic increase in brightness following an initial luminous (−17.4 mag) and long (∼100 days) unusual first peak (possibly precursor). SN 2023aew was classified as a Type IIb supernova during the first peak but changed its type to resemble a stripped-envelope supernova (SESN) after the marked rebrightening. We present comparisons of SN 2023aew’s spectral evolution with SESN subtypes and argue that it is similar to SNe Ibc during its main peak. P-Cygni Balmer lines are present during the first peak, but vanish during the second peak’s photospheric phase, before Hα resurfaces again during the nebular phase. The nebular lines ([O i], [Ca ii], Mg i], Hα) exhibit a double-peaked structure that hints toward a clumpy or nonspherical ejecta. We analyze the second peak in the light curve of SN 2023aew and find it to be broader than that of normal SESNe as well as requiring a very high 56Ni mass to power the peak luminosity. We discuss the possible origins of SN 2023aew including an eruption scenario where a part of the envelope is ejected during the first peak and also powers the second peak of the light curve through interaction of the SN with the circumstellar medium.

Investigation of unexpected silane ions caused by gas-phase reactions in Orbitrap gas chromatography-mass spectrometry.

The mass spectra of compounds containing dimethyl (phenyl)silyl group (-SiMe2Ph) sometimes exhibit unusual ion peaks when measured using Orbitrap gas chromatography-mass spectrometry (GC-MS). This would complicate the mass spectra and may limit the matching of spectral data with preexisting resources for compound annotation. These peaks were identified as products from reactions with residual water. A series of dimethyl (phenyl)silyl compounds were dissolved in methanol and investigated using Orbitrap GC-MS. Certain ions reacted with residual water in the C-trap. The reaction was confirmed using accurate mass and elemental composition analysis via MS studies, and the active center of the reaction was determined using density functional theory (DFT) calculations. Two types of gas-phase reactions between gaseous water and cations from a series of silanes were identified. DFT calculations indicate that silicon (Si) acts as the active center for these gas-phase water reactions. Compounds with multiple Si atoms generate a larger number of additional ions, which would complicate the mass spectra. The mass spectra of vinylsilanes and alkylsilanes with -SiMe2Ph indicate that the conjugated group linked to -SiMe2Ph can affect the water adduction process. Silane ions could react with residual water in the C-trap of an Orbitrap mass spectrometer. The mass spectra of these compounds may exhibit unexplained peaks arising from gas-phase reactions. Although these reactions may decrease spectral matching scores for compound annotation, they offer opportunities for systematic investigations into the mechanistic and kinetic aspects of high-energy ion reactivity.

Effects of shear-induced crystallization on the complex viscosity of lamellar-structured concentrated surfactant solutions.

Material relationships at low temperatures were determined for concentrated surfactant solutions using a combination of rheological experiments, cross-polarized microscopy, calorimetry, and small angle X-ray scattering. A lamellar structured 70 wt% solution of sodium laureth sulfate in water was used as a model system. At cold temperatures (5 °C and 10 °C), the formation of surfactant crystals resulted in extremely high viscosity. The bulk flow behavior of multi-lamellar vesicles (20 °C) and focal conic defects (90 °C) in the lamellar phase was similar. Shear-induced crystallization at temperatures higher than the equilibrium crystallization temperature range resulted in an unusual complex viscosity peak. The effects of processing-relevant parameters including temperature, cooling time, and applied shear were investigated. Knowledge of key low-temperature structure-property-processing relationships for concentrated feedstocks is essential for the sustainable design and manufacturing of surfactant-based consumer products for applications such as cold-water laundry.

Bronchiolitis trends in out-of-hospital urgent care services in the Community of Madrid: Observational study, 2016–2023

IntroductionBronchiolitis poses a considerable challenge during its seasonal peak, overwhelming the material and human resources available to care for affected patients. As a result, interhospital transfers increase exponentially. We did not find any studies analysing the characteristics of patients with bronchiolitis managed in out-of-hospital urgent care (OHUC) services and the impact of the COVID-19 pandemic on the epidemiology of bronchiolitis. ObjectiveTo establish the characteristics of paediatric and neonatal patients with acute bronchiolitis (AB) managed in OHUC services in the Community of Madrid and to analyse the impact of the COVID-19 pandemic on the epidemiology of bronchiolitis. MethodsRetrospective cross-sectional observational and descriptive study carried out in OHUC settings in the Community of Madrid between 2016 and 2023. We included patients with a diagnosis of acute bronchiolitis based on the ICD-10 codes documented in the electronic records of urgent care visits and interhospital transports. We collected data on sociodemographic, clinical and treatment (ventilation and medication) variables. ResultsThe sample included 630 patients with AB: 343 managed in non-neonatal OHUC (non-neo) services and 287 by the mobile neonatal intensive care unit transport team (NTT). The median age was 3.7 months (IQR, 2.8–4.7) in patients in the non-neo OHUC group and 19 days (IQR, 14.2−23.7) in the NTT group. There was a statistically significant increase in age in the 2020/2021 season in the non-neo OHUC group. The severity score was significantly higher in the NTT group. There was an unusual peak in bronchiolitis cases in June 2021, coinciding with the end of the 4th wave of the COVID-19 pandemic. The incidence of bronchiolitis was highest after the 6th wave of the pandemic (13.5 cases per 10 000 children aged < 2 years). ConclusionsThe median age of paediatric patients with AB managed in OHUC services increased following the end of the lockdown imposed due to the COVID-19 pandemic, which was probably associated with the lack of exposure to the viruses that cause it. This also may explain why the incidence of bronchiolitis was highest in the season following the 6th wave of the pandemic. The severity score was higher in neonatal patients. Epidemiological surveillance, the introduction of protocols and the implementation of an ongoing training programme for non-specialized health care staff involved in the transport of these patients could improve their management.

Evolución de la bronquiolitis en los servicios de urgencias extrahospitalarias de la Comunidad de Madrid: estudio observacional 2016-2023

IntroductionBronchiolitis poses a considerable challenge during its seasonal peak, overwhelming the material and human resources available to care for affected patients. As a result, interhospital transfers increase exponentially. We did not find any studies analysing the characteristics of patients with bronchiolitis managed in out-of-hospital urgent care (OHUC) services and the impact of the COVID-19 pandemic on the epidemiology of bronchiolitis. ObjectiveTo establish the characteristics of paediatric and neonatal patients with acute bronchiolitis (AB) managed in OHUC services in the Community of Madrid and to analyse the impact of the COVID-19 pandemic on the epidemiology of bronchiolitis. MethodsRetrospective cross-sectional observational and descriptive study carried out in OHUC settings in the Community of Madrid between 2016 and 2023. We included patients with a diagnosis of acute bronchiolitis based on the ICD-10 codes documented in the electronic records of urgent care visits and interhospital transports. We collected data on sociodemographic, clinical and treatment (ventilation and medication) variables. ResultsThe sample included 630 patients with AB: 343 managed in non-neonatal OHUC (non-neo) services and 287 by the mobile neonatal intensive care unit transport team (NTT). The median age was 3.7months (IQR: 2.8-4.7) in patients in the non-neo OHUC group and 19days (IQR: 14.2-23.7) in the NTT group. There was a statistically significant increase in age in the 2020/2021 season in the non-neo OHUC group. The severity score was significantly higher in the NTT group. There was an unusual peak in bronchiolitis cases in June 2021, coinciding with the end of the fourth wave of the COVID-19 pandemic. The incidence of bronchiolitis was highest after the sixth wave of the pandemic (13.5 cases per 10,000 children aged <2years). ConclusionsThe median age of paediatric patients with AB managed in OHUC services increased following the end of the lockdown imposed due to the COVID-19 pandemic, which was probably associated with the lack of exposure to the viruses that cause it. This also may explain why the incidence of bronchiolitis was highest in the season following the sixth wave of the pandemic. The severity score was higher in neonatal patients. Epidemiological surveillance, the introduction of protocols and the implementation of an ongoing training programme for non-specialized health care staff involved in the transport of these patients could improve their management.

Synthesis, characterization, and photoluminescence of zinc oxide ultra-thin nanowires

Ultra-thin Zinc oxide nanowires were prepared by a simple thermal evaporation method using a suitable amount of lead sulfide as an additive. It has been found that the nanowires are single crystalline of zincate grown along [1 0 1] direction. The transmission electron microscopy images show that nanowires consist of smooth ultra-thin cantilever-like with a diameter in the range of 10–20 nanometer (nm) and length of few microns. At room temperature, the photoluminescence spectra exhibit unusual strong broad peaks extending from the visible to near infrared (∼500–800 nm). The synthesized nanowires can serve as a novel platform for electrochemical and nano-biomolecular applications.

The impact of the COVID-19 pandemic on pediatric acute conjunctivitis disease trends

The COVID-19 pandemic notably influenced the transmission of infectious diseases across various age groups. In this study, we assessed its impact on pediatric acute conjunctivitis trends in southern Israel. We analyzed acute conjunctivitis diagnoses from 2017 to 2022, categorizing them into pre-lockdown, lockdown, and post-lockdown intervals. A control group of non-infectious dermatologic conditions was included. Time-series analysis, adjusted for seasonality, was employed. Pre-lockdown data indicated steady conjunctivitis diagnoses, primarily in winter. Post-lockdown interval exhibited an added summer peak before the regular winter surge. The lockdown saw a 56% decline in diagnoses, most pronounced in younger ages. Post-lockdown observed a 7% overall drop with age-specific variations. The acute conjunctivitis IRR was 0.44 (95% CI 0.39–0.49) during lockdowns and 0.93 (95% CI 0.86–1.02) post-lockdowns. Control group IRRs were 0.84 (95% CI 0.78–0.89) and 0.90 (95% CI 0.84–0.96), respectively, with the 0–5 age range demonstrating significant disparities. Pediatric acute conjunctivitis in southern Israel decreased significantly during the pandemic. Post-lockdown patterns varied by age group. An unusual summer peak in cases was observed post-lockdown; this peak may be influenced by a combination of altered behaviors in the summer and possibly increased susceptibility to infection.

Application of real-time PCR-based multicolor melting curve with automatic analysis system in pregestational and prenatal thalassemia diagnoses.

To evaluate the value of the real-time PCR-based multicolor melting curve analysis (MMCA) with an automatic analysis system used in a mass thalassemia screening and prenatal diagnosis program. A total of 18,912 peripheral blood samples from 9456 couples and 1150 prenatal samples were detected by MMCA assay. All prenatal samples were also tested by a conventional method. Samples with unknown melting peaks, unusual peak height ratios between a wild allele and a mutant allele, or a discordant phenotype-genotype match were further studied by using multiplex ligation-dependent probe amplification (MLPA) or Sanger sequencing. All MMCA results were automatically analyzed and manually checked. The consistency between MMCA assay and conventional methods among prenatal samples was investigated. Except for initiation codon (T>G) (HBB:c.2T>G), all genotypes of thalassemia inside the scope of conventional methods were detected by MMCA assay. Additionally, 27 carriers with 10 rare HBB variants, 13 with α fusion gene, 1 with a rare deletion in α globin gene, and 1 with rare HBA variant were detected by using MMCA assay. MMCA can be an alternative approach used in routine thalassemia carrier screening and prenatal diagnosis for its high throughput, sufficient stability, low cost, and easy operation.

Simulation based analysis of the partial shading at different locations on polycrystalline PV array

Photovoltaic (PV) technologies have definite environmental advantages over other power generation techniques. No matter many technologies are used, PV power generation emits no emissions. Solar cells and PV modules are produced using a variety of manufacturing techniques, and as with any energy source or product, there are no dangers to the environment, human health, and safety associated with these processes. Like any other device, even PV cells and modules go under degradation due numerous reasons. Shading is one such mode of degradations which directly impact the output of a PV system. Along with that the output power drastically get impacted. There is a drop in the output power and the electrical characteristics gets distorted. During shading condition the characteristics curves,Power - Voltage and Current-Voltage curve are seen with unusual peaks which is the exact reason for the presence of shading in the module. The paper presents the various impact on the curves which confirm the presence of power loss due to shading.

Tunable electron-flexural phonon interaction in graphene heterostructures.

Peculiar electron-phonon interaction characteristics underpin the ultrahigh mobility1, electron hydrodynamics2-4, superconductivity5 and superfluidity6,7 observed in graphene heterostructures. The Lorenz ratio between the electronic thermal conductivity and the product of the electrical conductivity and temperature provides insight into electron-phonon interactions that is inaccessible to past graphene measurements. Here we show an unusual Lorenz ratio peak in degenerate graphene near 60 kelvin and decreased peak magnitude with increased mobility. When combined with ab initio calculations of the many-body electron-phonon self-energy and analytical models, this experimental observation reveals that broken reflection symmetry in graphene heterostructures can relax a restrictive selection rule8,9 to allow quasielastic electron coupling with an odd number of flexural phonons, contributing to the increase of the Lorenz ratio towards the Sommerfeld limit at an intermediate temperature sandwiched between the low-temperature hydrodynamic regime and the inelastic electron-phonon scattering regime above 120 kelvin. In contrast to past practices of neglecting the contributions of flexural phonons to transport in two-dimensional materials, this work suggests that tunable electron-flexural phonon couping can provide a handle to control quantum matter at the atomic scale, such as in magic-angle twisted bilayer graphene10 where low-energy excitations may mediate Cooper pairing of flat-band electrons11,12.

Charge carrier transport and polarization in M/PZT/M structures

A model of non-stationary charge carrier transport in M/PZT/M ferroelectric structures has been developed. It is assumed that, at room temperature, electrons generated by oxygen vacancies are captured by Ti+3 levels and move between them under the action of electric fields caused by the external bias and polarization. The polarization distribution in a PZT film is described with varying degrees of complexity, from a constant value outside the defect layers to one determined by the equation following from the Landau–Ginzburg theory. The numerical simulation performed made it possible to explain the reasons and conditions for the appearance of current–voltage characteristics with unusual current peaks, to show the existence of several solutions in the Landau–Ginzburg model for a film with Schottky barriers, and to reveal the response of charged domain walls to an applied voltage.

Quantifying changes in respiratory syncytial virus-associated hospitalizations among children in Texas during COVID-19 pandemic using records from 2006 to 2021.

To quantify changes on RSV- associated hospitalizations during COVID-19 pandemic, among children four years of age or younger at the state and county levels of Texas using routinely acquired hospital admission records. We used the Texas Public Use Data Files (PUDF) of the Department of State Human Services (DSHS) to obtain hospital admissions and healthcare outcomes from 2006 to 2021. We used the 2006-2019 period to estimate a long-term temporal trend and predict expected values for 2020-2021. Actual and predicted values were used to quantify changes in seasonal trends of the number of hospital admissions and mean length of hospital stay. Additionally, we calculated hospitalization rates and assessed their similarity to rates reported in the RSV Hospitalization Surveillance Network (RSV-NET). An unusually low number of hospitalizations in 2020 was followed by an unusual peak in the third quarter of 2021. Hospital admissions in 2021 were approximately twice those in a typical year. The mean length of hospital stay typically followed a seasonal trend before COVID-19, but increased by a factor of ∼6.5 during the pandemic. Spatial distribution of hospitalization rates revealed localized healthcare infrastructure overburdens during COVID-19. RSV associated hospitalization rates were, on average, two times higher than those of RSV-NET. Hospital admission data can be used to estimate long-term temporal and spatial trends and quantify changes during events that exacerbate healthcare systems, such as pandemics. Using the mean difference between hospital rates calculated with hospital admissions and hospital rates obtained from RSV-NET, we speculate that state-level hospitalization rates for 2022 could be at least twice those observed in the two previous years, and the highest in the last 17 years.

Neural Network-Based Analysis on the Unusual Peak of Cavitation Performance of a Mixed Flow Pipeline Pump

Neural Network-Based Analysis on the Unusual Peak of Cavitation Performance of a Mixed Flow Pipeline Pump

Understanding the hydroxyl adsorption behavior at Pt electrode surface in high-temperature alkaline solutions

Since the application in fuel cell, the electrochemical adsorption of hydroxyl has received considerable attention in recent years. While most research mainly focus on the room temperature, in this paper, the electrochemical adsorption of hydroxyl in alkaline solution at high temperature was investigated. An unusual oxidation peak was observed at −0.27 V, suggesting new behavior of hydroxyl adsorption occurred. As is known two kinds of cation hydrated clusters exist in alkaline solution, (H 2 O) x− 1 M + --H 2 O--O ad H and (H 2 O) x M + --O ad H. For K + and Cs + , the cluster shows unstable structure due to the weak interaction between hydrated cation and OH − especially at high temperature. However, For Li + , Na + the cluster structure would be stable, as the interaction force between the hydrated cation and OH − is so strong. It was revealed that the unusual oxidation peak has some relationship with the (H 2 O) x −1 M + --H 2 O--O ad H cluster (K + and Cs + ) absorbed at Pt electrode surface. When the temperature was raised, (H 2 O) x −1 M + --H 2 O- and -O ad H was disconnected, then the O ad H absorbed at Pt surface got oxidated. Based on the SEM observation, it was showed the unusual electrochemical oxidation reaction would generate platinum oxides, blocking the reactive sites at Pt electrode surface, thus reducing the electrochemical reactivity of Pt electrode. Accordingly, parameters of alkaline concentration and temperature were systematically studied, it was found that increase temperature or alkaline concentration was in favor of the unusual oxidation reaction. This study provides more understanding of hydroxyl adsorption behavior at Pt electrode surface for the high temperature water solution environment.

Spectral Characterization of Parent Soils From Globally Important Dust Aerosol Entrainment Regions

AbstractWe investigated the variation in the mineralogical composition of surface soil samples from a wide range of atmospheric dust aerosol generating regions. These soils likely have mineral compositions similar to dust aerosols. We measured the visible, shortwave infrared (VSWIR) and long wave infrared (LWIR) reflectance spectra, as well as LWIR transmission spectra and carried out linear spectral mixture modeling on the transmission data. The spectroscopically identified minerals were compared with the mineralogy previously obtained using X‐ray diffraction (XRD) and optical microscopy (OM). The results showed that VSWIR is very sensitive to iron‐bearing minerals and better identifies their presence and type compared to XRD and OM. Clay minerals and carbonates have multiple distinct absorptions features in SWIR but are often overlapping, limiting our ability to uniquely assign spectral features. LWIR reflectance easily distinguishes carbonates, even in trace amounts that were not identified with other techniques. LWIR reflectance spectra for silicates were more complicated to interpret. In some samples, we were able to identify Si‐O features diagnostic of common silicates; however, in most cases these features were absent, and an unusual new peak (∼7.4–7.9 μm) was observed. LWIR transmission is characterized by strong absorption that arises from overlapping features from multiple silicate minerals, but carbonates are readily identifiable. Spectroscopy is complementary to XRD and can help identify additional minerals in these soil samples. Our results can help improve global soil atlases and can be used to support interpretation and validation of data acquired by current and future remote sensing instruments.

Diurnal Variation of Summer Monsoon Season Precipitation Over Southern Hainan Island, China: The Role of Boundary Layer Inertial Oscillations Over Indochina Peninsula

AbstractIn June after the onset of the East Asian summer monsoon season, rainfall on the south side of Hainan Island (HNI) of China exhibits a trimodal pattern with an unusual peak near noon. A typical case of 20 June 2017 is chosen to analyze the mechanisms through a convection‐permitting simulation together with rainfall observations. Clockwise rotation in low‐level winds is found at and off the coast of south HNI, leading to maximum onshore southwesterly winds in the late morning that is closely linked to the diurnal variation of rainfall. The offshore diurnal variations of low‐level winds are tracked upstream and attributed to boundary layer inertial oscillations over the inland plain of Indochina Peninsula. In addition, a short wide gap comprised mostly of hills lower than 700 m is located across the higher Annamite Range along the east coast of the Peninsula, right upstream of HNI. Nocturnal boundary layer low‐level jet (LLJ) forming over the plain passes through the gap with significant acceleration due to gap channeling and downslope flow effects, reaching peak intensity off the Peninsula coast at around 09 local standard time (LST). The enhanced LLJ propagates downstream towards HNI and impinges on the mountains at around 12 LST when rainfall reaches peak there. As the inertial‐oscillation‐indued perturbation winds approaching the Island weaken and eventually reverse direction, lifting weakens and low‐level stability increases as descending motion develops offshore. Rainfall on the southern Island therefore dissipates in late afternoon.

Electronic absorption spectral analysis of chlorin-based dyad sensitizers by TD-DFT calculations

As part of our studies of chlorophyll-based sensitizers for solar energy applications, we recently synthesized two dyad panchromatic chromophores of chlorin-indoline (Chl-Ind) and chlorin-carotenoid (Chl-Car) conjugates aiming at the wider range of sunlight utilization. By comparing the absorption spectra of these dyad sensitizers in various solvents, we found that each chromophore unit in Chl-Ind showed drastic red-shift when measured in polar solvents, while the spectra of Chl-Car showed lesser solvent effects. To elucidate the origin of such solvatochromism by time dependent density functional theory (TD-DFT) calculations with molecular dynamics studies, we decided to compare the estimation results of TD-DFT/CAM-B3LYP (M06-2X and ωB97X-D)/6-31(d,p) using polarizable continuum model (H2O and THF) with the absorption spectra for Chl-Ind and Chl-Car, together with their sole chromophore units methyl trans-32-carboxy-pyropheophorbide-a (Chl), methyl ester of indoline dye D102 (Ind), and β–apo-8ʹ-carotenoic acid ethyl ester (Car). The results revealed that the unusual peak shifts of Chl and Ind moieties in Chl-Ind dyad could be most properly reproduced at ωB97X-D density functionals. This is likely because ωB97X-D contains dispersion-corrected and long-range corrected functionals. The destabilized HOMO−1 is expected to contribute to the red-shift of Ind peak in the dyad. Our results would provide useful information for the selection of computational methods to anticipate spectral characteristics of covalently-linked multi-chromophores in advance.

Two-channel anomalous Hall effect originating from the intermixing in Mn2CoAl/Pd thin films

The anomalous Hall effect (AHE) is an electronic transport phenomenon with rich physics. In thin magnetic films and multilayers, an unusual peak observed in AHE is often identified as the topological Hall effect (THE), induced by topologically nontrivial spin textures. However, it is a challenge to determine whether this unusual peak truly originates from such spin textures or is an artifact due to inhomogeneities. In this work, we systematically study the Pd thickness and temperature dependence of the Hall effect in ${\mathrm{Mn}}_{2}\mathrm{CoAl}$/Pd thin films. We observe an unusual peak in the Pd thickness dependence and rule out that the origin of the peak is from the topologically nontrivial spin textures by directly imaging the magnetic domain structures. We also build a model for the AHE based on the sum of contributions from ${\mathrm{Mn}}_{2}\mathrm{CoAl}$ and an intermixed CoPd alloy. These materials have opposite signs of the AHE and different coercive fields, which successfully explains the thickness and temperature behaviors of the unusual peak. Our results show that the interface mixing layer can play an important role in the interpretation of the AHE in ferromagnet/heavy metal systems.