Faster Transit Time Research Articles

Highly Sensitive Two‐Dimensional Ruddlesden‐Popper Perovskites for Thermochromic Smart Windows

AbstractWith the growing demand for high‐performance smart windows, the discover of a class of thermochromic materials with reversible cycling and rapid response characteristics has become urgent. In this work, we have uncovered a two‐dimensional (2D) Ruddlesden‐Popper (RP) phase halide perovskite, (PMA)2MAPb2I7−xClx, where PMA=C6H5CH2NH3 and MA=CH3NH3, exhibiting exceptional reversible thermochromic properties. The 2D RP phase perovskite thin film features a low transition temperature (Tc=30 °C from the hydrated state to the hot state, along with a fast transition time of 40 s. Furthermore, the addition of 0.5 times excess MAI significantly enhances the visible light transmittance of the hydrated state. Characteristic hydration peaks in X‐ray diffraction patterns and O−H bond absorption peaks Fourier‐transform infrared spectra are observed in the thin film in its hydrated state, which disappear in the hot state, validating its reversible thermochromic properties. Additionally, a solar cell based on the thermochromic 2D RP phase thin film achieves a power conversion efficiency of 2.31 %, offering a promising solution for advanced smart window technologies.

Electrical manipulation of the spins in phosphorene double quantum dots

We investigate electric dipole spin resonance (EDSR) induced by an oscillating electric field within a system of double quantum dots formed electrostatically in monolayer phosphorene. Apart from the observed anisotropy of effective masses, phosphorene has been predicted to exhibit anisotropic spin-orbit coupling. Here, we examine a system consisting of two electrons confined in double quantum dots. A single-band effective Hamiltonian together with the configuration interaction theory is implemented to simulate the time evolution of the ground state. We examine spin flips resulting from singlet-triplet transitions driven by external AC electric fields, both near and away from the Pauli blockade regime, revealing fast sub-nanosecond transition times. Furthermore, we analyze the impact of anisotropy by comparing dots arranged along a different crystal axis. The sub-harmonic multi-photon transitions and Landau-Zener-Stückelberg-Majorana transitions are discussed. We show modulation of spin-like and charge-like characteristics of the qubit through potential detuning.

Investigation of the Source of Iceland Basin Freshening: Virtual Particle Tracking with Satellite-Derived Geostrophic Surface Velocities

In the 2010s, a large freshening event similar to past Great Salinity Anomalies occurred in the Iceland Basin that has since propagated into the Irminger Sea. The source waters of this fresh anomaly were hypothesized to have come from an eastward diversion of the Labrador Current, a finding that has since been supported by recent modeling studies. In this study, we investigate the pathways of the freshwater anomaly using a purely observational approach: particle tracking using satellite altimetry-derived surface velocity fields. Particle trajectories originating in the Labrador Current and integrated forward in time entered the Iceland Basin during the freshening event at nearly twice the frequency observed prior to 2009, suggesting an increased presence of Labrador Current-origin water in the Iceland Basin and Rockall Trough during the freshening. We observe a distinct regime change in 2009, similar to the timing found in the previous modeling papers. These spatial shifts were accompanied by faster transit times along the pathways which led to along-stream convergence and more particles arriving to the eastern subpolar gyre. These findings support the hypothesis that a diversion of relatively fresh Labrador Current waters eastward from the Grand Banks can explain the unprecedented freshening in the Iceland Basin.

Guava fibre characterization and effects on digestibility, fermentation products, gastrointestinal transit time and palatability of dry diets for dogs.

The use of fruit fibres as a way of reusing industrial waste is attractive and necessary, increasing the efficiency and reducing the environmental impact of the industry. This study characterized guava fibre as a fibrous ingredient and evaluated its effects when included in extruded diets for dogs on nutrient digestibility, faecal traits, fermentation products, gastrointestinal transit timeand palatability. Four diets were formulated: CO (control diet, no fibrous ingredients added), GF3 (3% guava fibre), GF6 (6% guava fibre)and GF12 (12% guava fibre). The guava fibre was added to diets in replacement of maize, with small adjustments in the other ingredients to ensure similar contents of protein and fat. The diets were fed to 24 adult Beagle dogs (6 per diet) during 15 days for adaptation followed by 15 days for assessment of digestibility, fermentation end productsand gastrointestinal transit time. The palatability of G6 and G12 treatments was evaluated against the CO by the two-pan test. Results were compared by analysis of variance and polynomial contrasts according to the guava fibre inclusion level (p < 0.05). The addition of guava fibre did not change nutrient intake except for the increase on dietary fibre (p < 0.001). Fibre inclusion resulted in a quadratic reduction in total tract apparent digestibility for dry matter, organic matter, crude protein and crude energy (p < 0.001), and on the metabolizable energy content of the foods (p < 0.001). Guava fibre addition did not change the faecal concentration of ammonia, lactic acid, faecal pHand branched chain fatty acids but it decreased acetic and propionic acids concentration (p < 0.01). The inclusion of 12% guava fibre did result in a faster transit time (p = 0.046) compared to the control diet. Guava fibre can be characterized as a novel insoluble non-fermentable fibre source that could be safely used in levels up to 12% in canine extruded diets.

A PWM Method for Reducing dv/dt and Switching Losses in Two-Stage Power Converters

Today's semiconductor devices are accompanied by high switching frequencies (> kilo-hertz) and small transition times (< micro-seconds). Such fast transition times are accompanied by undesirable effects such as voltage overshoots at the load terminals, ground leakage currents, wide-band electromagnetic noise, etc. With the advent of wide band-gap devices, several applications are moving towards higher switching frequency operation with at-least an order of magnitude reduction in transition times. While these characteristics are considered necessary to break the next-generation barriers in power density, efficiency and applicability, the undesirable effects due to faster transitions are expected to present obstacles. This work proposes a PWM approach to modify the shape of the switching voltages to overcome the disadvantages of the fast transition times without any increase in switching losses. In fact, several of the switching transitions feature ZVS operation, resulting in reduced switching losses. The paper discusses the analytical details of the approach using a simple DC-DC boost-buck converter and extends it to a DC to three-phase AC converter using the principles of space vector modulation. The paper presents detailed simulation and comparative results in terms of voltage over-shoots over long cables, loss calculations and electromagnetic noise. Results from a laboratory-scale working prototype confirm the benefits of the proposed approach in terms of EMI and loss reduction.

Structural, morphological and ammonia sensing properties of spray deposited CeO2 films

CeO2 films is formed onto glass substrates by simple spray deposition technique using pyrolytic reaction of cerium nitrate hexahydrate which is termed as as-deposited film and the CeO2 film which is kept in furnace at 350 °C in the air atmosphere for 120 min is termed as heat treated film. The characteristics like structural, spectral, morphological and optical of both the films are studied. The structural analysis affirms that both the films are in cubic structure with polycrystalline nature. Uniform spherical shaped morphology is observed by SEM. The heat-treated film is chosen for the analysis of sensing characteristics for ammonia vapour with various concentrations (0.5–100 ppm) at room temperature. The better sensing performance with fast response and recovery times are achieved for 25 ppm of NH3. The room temperature response, fast transition time and perfect repeatability are achieved for low concentration (0.5 ppm) of NH3.

Variable Stiffness Technologies for Soft Robotics: A Comparative Approach for the STIFF-FLOP Manipulator

Soft robots offer a number of advantages over traditional rigid robots in applications such as minimally invasive surgery, where safety and dexterity are required. In previous works, the STIFF-FLOP manipulator has been introduced as a new concept of using soft materials to develop endoscopic tools with high dexterity and intrinsic safety. However, due to its inherent low stiffness, the ability to generate higher forces and stability when required remains to be further explored. In the state-of-the-art technology, there is no optimal solution that satisfies all the desired requirements in terms of miniaturized dimensions, free lumen for passing tools up to the tip, stiffness variation, and dexterity. In this paper, we compare different variable stiffness technologies and present a novel design that comprises a stiffening system based either on a fiber jamming (FJ) transition or low-melting-point alloys (LMPAs) that can be embedded in the manipulator to widen its applicability by increasing its stability and load bearing capability. The two approaches have been evaluated and compared in terms of variable stiffness capability and dexterity. The results suggest that the LMPA-based solution significantly outperforms previous approaches using similar designs with a higher stiffness variation combined with a good degree of flexibility, while the solution based on FJ guarantees fast transition times and fully satisfies the required safety measures.

Droughts can reduce the nitrogen retention capacity of catchments

Abstract. In 2018–2019, Central Europe experienced an unprecedented 2-year drought with severe impacts on society and ecosystems. In this study, we analyzed the impact of this drought on water quality by comparing long-term (1997–2017) nitrate export with 2018–2019 export in a heterogeneous mesoscale catchment. We combined data-driven analysis with process-based modeling to analyze nitrogen retention and the underlying mechanisms in the soils and during subsurface transport. We found a drought-induced shift in concentration–discharge relationships, reflecting exceptionally low riverine nitrate concentrations during dry periods and exceptionally high concentrations during subsequent wet periods. Nitrate loads were up to 73 % higher compared to the long-term load–discharge relationship. Model simulations confirmed that this increase was driven by decreased denitrification and plant uptake and subsequent flushing of accumulated nitrogen during rewetting. Fast transit times (&lt;2 months) during wet periods in the upstream sub-catchments enabled a fast water quality response to drought. In contrast, longer transit times downstream (&gt;20 years) inhibited a fast response but potentially contribute to a long-term drought legacy. Overall, our study reveals that severe droughts, which are predicted to become more frequent across Europe, can reduce the nitrogen retention capacity of catchments, thereby intensifying nitrate pollution and threatening water quality.

Plasmonic internal-photoemission-based Si photodetector design suitable for optical communication.

We propose a high-performance plasmonic photodetector based on the internal photoemission (IPE) process for the C-band communication wavelength. This photodetector takes advantage of an embedded nanohole array in Schottky metal. Owing to localized surface plasmon resonance, the absorption of the active metal layer increases, which results in the generation of more hot carriers and subsequently compensates for the low efficiency of IPE-based photodetectors. Simulations show that for the proposed photodetector with 2-nm-thick Au, Cu, and Ag Schottky contacts, the absorptance dramatically enhances to 95.1%, 93.2%, and 98.2%, respectively, at the wavelength of 1.55 µm. For the detector based on Au, the highest external quantum efficiency of 25.3% and responsivity of 0.32 A/W are achieved at a reverse bias voltage of 1 V. Furthermore, the 3 dB bandwidth can exceed 369 GHz owing to the low capacitance of the structure and the fast transit time of carriers from the thin p-Si layer. Finally, by studying the current-voltage characteristics of the photodetector, it is shown that under the reverse bias voltage of 1 V, the dark current is 665 nA at room temperature, and by reducing the temperature to 200 K, it improves three orders of magnitude and decreases to 810 pA.

A single-dose, open-label, randomized, scintigraphic study to investigate the gastrointestinal behavior of 2 triple-combination cold products (acetaminophen, phenylephrine, and dextromethorphan) in healthy male volunteers

BackgroundCommon cold symptoms may be mitigated by products in caplet, nasal spray, and oral solution formulations, although variations exist in the bioavailability of the active ingredients contained within these products. Rapid gastric emptying (GE) of these active ingredients is important for reducing the delay between drug absorption and onset of cold symptom relief. Hot drink cold remedies are associated with greater comfort and may enhance the bioavailability of active ingredients. The objective of this study was to characterize the gastrointestinal transit of powder (reconstituted in hot water) and caplet formulations of commercially available multisymptom cold medications.MethodsThis was an open-label, single-dose, parallel-group study. Healthy male adults under fasted conditions were randomized 1:1 to receive a single dose of radiolabeled Theraflu Daytime Severe Cold and Cough powder for oral solution or radiolabeled Theraflu ExpressMax Daytime Severe Cold and Cough caplet. External gamma scintigraphy was utilized to monitor GE and intestinal transit of two radiolabeled drug formulations.ResultsA total of 28 participants completed the study. The mean ± SE GE onset times were 1.1 ± 0.3 min and 8.5 ± 1.8 min for powder and caplet formulations, respectively. The mean ± SE GE completion times were 121 ± 13 min and 65 ± 13 min, respectively. Despite the similar mean times to GE25%, the powder had later mean GE50% (23 ± 3.0 vs 16 ± 3.2 min, respectively) and GE90% (85 ± 12 vs 36 ± 9 min, respectively) than caplets. Caplets had a shorter overall GE half-life, lower total gastric exposure, and faster transit time through the small intestine versus the powder formulation. No serious safety events were observed.ConclusionThe results of this study in healthy male adults suggest that the Theraflu powder formulation had a more rapid GE onset but longer time to GE completion than the caplet formulation.Trial registrationClinicalTrials.govNCT03415243

Time‐multiplexed hysteretic control for single‐inductor dual‐input single‐output DC‐DC power converter

SummarySingle‐inductor multi‐input single‐output (SI‐MISO) switching DC‐DC power converter architecture is a cost effective solution to applications where multiple input sources are required to be managed with a limited space and cost. This paper presents a new time‐multiplexed hysteretic control (TMHC) scheme for SI‐DISO topology to decouple the power sharing among two input sources. Unlike previously reported solutions with discontinuous conduction or pseudo‐continuous conduction operation of the inductor, this paper focuses on how to keep the inductor current in a continuous conduction mode (CCM) and proposed a control scheme with considerably lower ripple current with fast transition time upon switching and higher efficiency. The mathematical proof using the expressions of inductor ripple current, comparison between efficiency and transition time from one level to other, is derived. Additionally, a low‐cost analog circuitry has been implemented to incorporate the proposed control scheme. Experimental results from the hardware prototype are given to verify the proposed control scheme.

Reliability of Poly-Si TFTs Under Voltage Pulse With Fast Transition Time

Reliability of Poly-Si TFTs Under Voltage Pulse With Fast Transition Time

Temperature Hypersensitive Organic Electroluminescence in a Reverse Biased, Frozen Polymer P–I–N Junction

AbstractSemiconductor junctions are among the most important material interfaces in modern technology. The solid polymer light‐emitting electrochemical cell (PLEC) possesses a semiconducting polymer homojunction that is reminiscent of a conventional p–n junction but also exhibits distinct features that are profoundly intriguing. The PLEC junction is formed under bias when the propagating p‐ and n‐doping fronts make contact. The PLEC junction can be immobilized by cooling after the initial junction formation. Further, the resulting frozen junction can be relaxed, or partially de‐doped into a p–i–n junction by controlled heating/cooling cycles. It is on such a frozen polymer p–i–n junction that the authors observed one of the most puzzling phenomena in organic electroluminescence (EL). The frozen p–i–n junction displays the brightest reverse bias (RB) EL ever imaged in a polymer junction and a large photovoltage. Moreover, the RB EL exhibits hypersensitivity to temperature, increasing in intensity by 22.6% K−1 when the de‐doped cell is cooled from 250 to 200 K. A model based on the tunnel injection of charge carriers with fast transit time across the intrinsic region explains the RB EL's hypersensitivity to temperature and super‐linear dependence on cell current.

Exhaled Hydrogen as a Marker of Intestinal Fermentation Is Associated with Diarrhea in Kidney Transplant Recipients.

Background: Diarrhea is common among kidney transplant recipients (KTR). Exhaled hydrogen (H2) is a surrogate marker of small bowel dysbiosis, which may drive diarrhea. We studied the relationship between exhaled H2 and diarrhea in KTR, and explored potential clinical and dietary determinants. Methods: Clinical, laboratory, and dietary data were analyzed from 424 KTR participating in the TransplantLines Biobank and Cohort Study (NCT03272841). Fasting exhaled H2 concentration was measured using a model DP Quintron Gas Chromatograph. Diarrhea was defined as fast transit time (types 6 and 7 according to the Bristol Stool Form Scale, BSFS) of 3 or more episodes per day. We studied the association between exhaled H2 and diarrhea with multivariable logistic regression analysis, and explored potential determinants using linear regression. Results: KTR (55.4 ± 13.2 years, 60.8% male, mean eGFR 49.8 ± 19.1 mL/min/1.73 m2) had a median exhaled H2 of 11 (5.0–25.0) ppm. Signs of small intestinal bacterial overgrowth (exhaled H2 ≥ 20 ppm) were present in 31.6% of the KTR, and 33.0% had diarrhea. Exhaled H2 was associated with an increased risk of diarrhea (odds ratio 1.51, 95% confidence interval 1.07–2.14 per log2 ppm, p = 0.02). Polysaccharide intake was independently associated with higher H2 (std. β 0.24, p = 0.01), and a trend for an association with proton-pump inhibitor use was observed (std. β 0.16 p = 0.05). Conclusion: Higher exhaled H2 is associated with an increased risk of diarrhea in KTR. Our findings set the stage for further studies investigating the relationship between dietary factors, small bowel dysbiosis, and diarrhea after kidney transplantation.

Determining How Critical Zone Structure Constrains Hydrogeochemical Behavior of Watersheds: Learning From an Elevation Gradient in California's Sierra Nevada

Concentration-discharge (C-Q) relations can provide insight into the dynamic behavior of the Critical Zone (CZ), as C-Q relations integrate the spatial distribution and timing of watershed hydrogeochemical processes. This study blends geomorphologic analysis, C-Q relations and reactive-transport modeling using a rich dataset from an elevation gradient of eight watersheds in the Southern Sierra Nevada, California. We found that the CZ structure exerts a strong control on the C-Q relations, and on the hydrogeochemical behavior of headwater watersheds. Watersheds with thin regolith, a large stream network, and limited water storage have fast mean transit times along subsurface flow lines, and show limited seasonal variability in ionic concentrations in streamflow (i.e. chemostatic behavior). In contrast, watersheds with thicker regolith, a small stream network and more water storage have longer transit times along subsurface flow lines, and exhibit greater chemical variability (i.e. chemodynamic behavior). Independent estimates of mean transit times and water storage from other isotopic, hydrologic and geophysical studies were consistent with results from modeling C-Q relations. The stream chemistry and its variability were controlled by lateral flow within the regolith, and no mixing with deep groundwater was needed to explain the observed chemical variability. This study opens the possibility to estimate water-storage capacity and mean transit times, and thus drought resistance in watersheds, by using quantitative modeling of C-Q relations.

Modeling and Optimization of Plasmonic Detectors for Beyond-CMOS Plasmonic Majority Logic Gates

In this work, we report the modeling and design of a high-speed Ge-based plasmonic detector coupled with a Metal-Insulator-Metal (MIM) plasmonic majority gate. The detector is designed to distinguish between multiple output levels of the integrated majority gate. Through numerical analyses we predict the proposed plasmonic detector has an intrinsic bandwidth beyond $\text{220 GHz}$ at an applied bias of only $\text{100 mV}$ . An asymmetric Metal-Semiconductor-Metal (MSM) configuration of the plasmonic detector ensures a dark current of a few nA which results in high sensitivity. The high electric field generated by the electrode asymmetry enables effective separation of the photogenerated carriers resulting in high photocurrent even at few mVs of applied bias. The low capacitance of less than $1fF$ arising from the small detector dimensions results in a high RC-limited bandwidth. Moreover, the narrow plasmonic Ge slot of the photodetector provides a short drift path and fast transit time for carriers. Unlike previously reported plasmonic detectors that use noble metals as electrodes, our proposed detector employs Al and Cu to meet CMOS compatibility requirements and thus can be a potential candidate for high-speed computational systems in industry-level applications. Additionally, the findings presented in the article will be helpful for the future realization of an integrated plasmonic system.

Keratin 14-dependent disulfides regulate epidermal homeostasis and barrier function via 14-3-3σ and YAP1.

The intermediate filament protein keratin 14 (K14) provides vital structural support in basal keratinocytes of epidermis. Recent studies evidenced a role for K14-dependent disulfide bonding in the organization and dynamics of keratin IFs in skin keratinocytes. Here we report that knock-in mice harboring a cysteine-to-alanine substitution at Krt14's codon 373 (C373A) exhibit alterations in disulfide-bonded K14 species and a barrier defect secondary to enhanced proliferation, faster transit time and altered differentiation in epidermis. A proteomics screen identified 14-3-3 as K14 interacting proteins. Follow-up studies showed that YAP1, a transcriptional effector of Hippo signaling regulated by 14-3-3sigma in skin keratinocytes, shows aberrant subcellular partitioning and function in differentiating Krt14 C373A keratinocytes. Residue C373 in K14, which is conserved in a subset of keratins, is revealed as a novel regulator of keratin organization and YAP function in early differentiating keratinocytes, with an impact on cell mechanics, homeostasis and barrier function in epidermis.

A novel intracochlear injection method for rapid drug delivery to vestibular end organs

BackgroundInjection into the inner ear through the round window (RW) or a cochleostomy is a reliable method for delivering drugs or viruses to the cochlea. This method has been less effective for fast deliveries to vestibular end organs. New MethodWe describe a novel approach for rapid delivery of drugs to the vestibular end organ via the oval window (OW) and scala vestibuli in 1–3 month old C57BL/6 mice. The OW was directly accessed through the external ear canal after ablating the tympanic membrane and middle ear ossicles. A canalostomy in the superior canal provided a low pressure point for faster transit of injected solution from the OW to the vestibular neuroepithelia, allowing for higher rates of injection. ResultsThe efficacy of this technique was shown by fast transit times of a colored artificial perilymph from the OW to the utricle and the ampullae of the horizontal and superior canals in ∼2 min. Following injection, the response of the vestibular nerve was preserved, as measured by the vestibular sensory evoked potentials (VsEP). Comparison with Existing MethodsPrevious studies have used posterior semicircular canals or the RW with canalostomy to gain access to vestibular end organs in mice. The OW with canalostomy, provides the means for high injection rates and fast and reliable delivery of drugs to vestibular hair cells and afferent terminals. ConclusionsThe presented method for injections through the OW provides rapid delivery of solutions to vestibular end organs without adversely affecting vestibular nerve responses measured by VsEP.

Chemical Characterization, Gastrointestinal Motility and Sensory Evaluation of Dark Chocolate: A Nutraceutical Boosting Consumers' Health.

We performed a comprehensive study encompassing chemical characterization and sensory evaluation of two types of dark chocolate, i.e., artisanal (Choco-A) and industrial (Choco-I), as well as an evaluation of onset of gastrointestinal symptoms and gastrointestinal motility in healthy subjects fed with dark chocolate. Proteomic, lipid and metabolite analysis were performed by LC-MS/MS analysis and the total phenol content and antioxidant activity were estimated in both types of chocolate. Fifty healthy volunteers joined the study of the sensory characteristics of both types of chocolate; another 16 subjects underwent the study of gallbladder and gastric emptying by functional ultrasonography and orocecal transit time by lactulose H2-breath test after ingestion of dark chocolate. Identification of polyphenols, amino acids and fatty acids was carried out in both types of chocolate analysed, and results confirmed their richness in polyphenols, amino acid derivatives and fatty acids (FAs) either saturated (stearic, myristic, palmitic, ecosanoic) or unsaturated (oleic and linolenic). For agreeability, Choco-A scored higher than Choco-I for smell, texture, and taste and they did not show significant differences in the gastrointestinal motility. In conclusion as for gastrointestinal motility studies, we report that the ingestion of a small amount of chocolate induced a mild gallbladder, gastric contraction and a fast transit time compared to the test meal in healthy subjects.

Digestible Energy Intake and Digestive Efficiency of Human-Managed North American River Otters (Lontra canadensis).

Diets currently provided to captive North American river otters (Lontra canadensis) are highly variable with different institutions providing various whole foods, commercial complete prepared diets, or combinations of both. This study investigated the digestible energy intake, gastrointestinal transit time, and digestive efficiency of three different diets being fed at three North Carolina institutions. Otters housed at Institution A (n = 3) were fed strictly fish. Otters housed at Institutions B (n = 3) and C (n = 2) were fed a majority fish based diet (58.5 and 74.1%, respectively), supplemented with fruits, vegetables, and supplemental protein sources as enrichment. There was an apparent trend between increased percentage of fish in the diet and faster transit time and higher digestive efficiency. As less fish was included in the diets, the GI transit time was longer (Institution A, 106 minutes; Institution B, 145 minutes; Institution C, 208 minutes). Median digestive efficiency was high for all three groups (A, 91.4%; B, 87.8%; C, 89.8%) but was higher for the institutions feeding fish. Additionally, the overall median gross energy intake for the eight animals in this study was 163.1 kcal/kgBM0.75/day (range: 92.2 to 260.7 kcal/kgBM0.75/day). While all three institutions had healthy otter populations, it appears that a higher fish diet should be further studied as the model North American river otter diet.