Gain Mechanism Research Articles

Effects of the anti-inflammatory drug budesonide on the gut microbiota and cytokine production of 13-lined ground squirrels during prehibernation fattening.

The gut microbiome is essential for maintaining organismal health. Gut microbiota may be disrupted through external factors like dietary change, which can lead to gut inflammation, resulting in obesity. Hibernating mammals develop low-grade gut inflammation when they accumulate fat deposits in preparation for hibernation, making them useful models for studying the relationship between the microbiome, inflammation, and weight gain. Nonsteroidal anti-inflammatory drugs and steroids are commonly used in humans to target gut inflammation, but how these drugs affect the gut microbiome and its stability is unclear. We investigated the effect of the glucocorticoid drug budesonide on the gut microbiome and cytokine levels of an obligate hibernator, the 13-lined ground squirrel, during the fattening season. We used 16S rRNA gene sequencing to characterize bacterial communities in the lumen and mucosa of the cecum and colon and measured proinflammatory [tumor necrosis factor-α (TNF-α)/interleukin 6 (IL-6)] and anti-inflammatory (IL-10) cytokine levels. Budesonide affected the microbiome only in the cecum lumen, where bacterial diversity was higher in the control group, and communities significantly differed between treatments. Across gut sections, Marvinbryantia and Enterococcus were significantly higher in the budesonide group, whereas Sarcina was higher in the control group. TNF-α and IL-6 levels were higher in control squirrels compared with the budesonide group, but there was no difference in IL-10 levels. Overall, budesonide treatment affected the microbial community and diversity of 13-lined ground squirrels in the cecum lumen. Our study presents another step toward developing ground squirrels as a model for studying the interaction between the microbiota and host inflammation.NEW & NOTEWORTHY Disruptions of gut microbiota can lead to inflammation, resulting in weight gain. Inflammation can be treated with budesonide, but how budesonide affects gut microbiota is unclear. Thirteen-lined ground squirrels experience low-grade gut inflammation during prehibernation fattening, which compares with human inflammation-weight gain mechanisms. We showed that budesonide treatment decreased microbiome diversity and lead to a shift in community in the cecum lumen. Our study supports developing ground squirrels as a model for studying microbiome-inflammation interactions.

Numerical investigation on thrust gain mechanism of helium injected solid–gas hybrid rocket motor

Numerical investigation on thrust gain mechanism of helium injected solid–gas hybrid rocket motor

On the pathogenesis of obesity: causal models and missing pieces of the puzzle.

Application of the physical laws of energy and mass conservation at the whole-body level is not necessarily informative about causal mechanisms of weight gain and the development of obesity. The energy balance model (EBM) and the carbohydrate-insulin model (CIM) are two plausible theories, among several others, attempting to explain why obesity develops within an overall common physiological framework of regulation of human energy metabolism. These models have been used to explain the pathogenesis of obesity in individuals as well as the dramatic increases in the prevalence of obesity worldwide over the past half century. Here, we summarize outcomes of a recent workshop in Copenhagen that brought together obesity experts from around the world to discuss causal models of obesity pathogenesis. These discussions helped to operationally define commonly used terms; delineate the structure of each model, particularly focussing on areas of overlap and divergence; challenge ideas about the importance of purported causal factors for weight gain; and brainstorm on the key scientific questions that need to be answered. We hope that more experimental research in nutrition and other related fields, and more testing of the models and their predictions will pave the way and provide more answers about the pathogenesis of obesity than those currently available.

Giant Tunneling Electro‐Resistance in Ultrathin Ferroelectric Tunnel Junctions: The Interface Barrier Gain Mechanism

AbstractUltrathin ferroelectric tunnel junctions (FTJs) hold considerable promise for next‐generation, high‐speed, low‐power, and high‐density nonvolatile memory applications. Achieving a substantial tunneling electro‐resistance (TER) remains a challenge as the ferroelectric layer is thinned to nanoscale dimensions, often resulting in a diminished or lost polarization. An innovative interface barrier gain mechanism is introduced, employing interface electronic state modulation to precisely control the size of an additional interface barrier. This strategy lessens the dependency of the tunneling barrier on ferroelectric polarization strength, facilitating a remarkable TER even at ferroelectric thicknesses as minimal as ≈1 nm. The focus is on composite FTJs using In2Se3/MTe2 (M = Mo, W), where the inclusion of an MTe2 monolayer disrupts the asymmetric electrode configuration. The weak ferroelectric polarization reversal of the In2Se3 monolayer effectively modulates the electronic state coupling at the In2Se3/MTe2 interface. This modulation leads to variations in the width and height of the Schottky barrier at the heterojunction‐electrode interface corresponding with the ferroelectric polarization reversal, establishing a beneficial Ohmic contact in the “on” state and resulting in an exponential TER increase up to 5.4 × 106%. This work introduces a universal mechanism to overcome the thickness limitations traditionally associated with enhancing TER, marking a significant advancement in the development of ultrathin ferroelectric nonvolatile devices.

Emission mechanisms in low-threshold UV random laser based on ZnO microrod array

Despite rather extensive study of the random lasing effect in ZnO structures, the issue of the optical gain mechanisms in microstructured ZnO random lasers remains poorly understood. In this work, the radiative properties of an array of vertically aligned ZnO microrods, synthesized by a modified thermal evaporation method, were studied. The microrods exhibited lengths up to 60 μm and diameters ranging from 1 to 5 μm. Random lasing from a microrod array was observed in the near-UV range (with a laser emission peak wavelength of ∼391 nm) with a threshold down to 40 kW/cm2 under optical excitation. An analysis of the nature of optical gain in the grown structure was conducted at various temperatures. It was found that at room temperature, two-phonon-assisted exciton recombination is the main process leading to light amplification.

Hypoactivation of the central auditory system in listeners who are hypertolerant of background noise.

Listeners exhibit varying levels of tolerance for background noise during speech communication. It has been proposed that low tolerance of background noise may be the consequence of abnormally amplified gain in the central auditory system (CAS). Here, using a dataset of young adults with normal hearing thresholds, we asked whether central gain mechanisms might also explain cases of hypertolerance of background noise, as well as cases of reduced, but not abnormal, tolerance. We used the auditory brainstem response to derive a measure of CAS gain (wave V/wave I ratio) to compare listeners' background noise tolerance while listening to speech, grouping them into three categories: hyper, high, and medium tolerance. We found that hypertolerant listeners had reduced CAS gain compared to those with high tolerance. This effect was driven by wave V not wave I. In addition, the medium tolerant listeners trended toward having reduced wave I and reduced wave V amplitudes and generally higher levels of exposure to loud sound, suggestive of the early stages of noise-compromised peripheral function without an apparent compensatory increase in central gain. Our results provide physiological evidence that 1) reduced CAS gain may account for hypertolerance of background noise but that 2) increased CAS gain is not a prerequisite for medium tolerance of background noise.NEW & NOTEWORTHY Our findings strengthen the proposed mechanistic connection between background noise tolerance and auditory physiology by suggesting a link between hypertolerance and reduced central auditory gain, measured by the auditory brainstem response.

Experimental evidence on the feasibility of employing a replica symmetry breaking classification random laser.

Replica symmetry breaking (RSB) has been introduced in a random laser to investigate the interactions between disorder and fluctuations. In this work, the dynamic difference between four non-energy transfer and Förster resonance energy transfer (FRET)-assisted random laser systems is investigated based on RSB. It is found that FRET is one of the key factors influencing RSB, and it is demonstrated that RSB in a random laser is not robust. This dynamic difference can be attributed to the different disorders induced by the gain mechanism in different random laser systems. This provides experimental evidence and theoretical support for the classification feasibility of RL with different emission mechanisms employing RSB.

High-speed waveguide lateral Ge/Si avalanche photodetector for C-band and L-band

Germanium/silicon (Ge/Si) avalanche photodiodes (APDs) have been intensively investigated and are widely used in various fields, such as near-infrared detection and quantum communication. However, existing research of Ge/Si APDs mostly focuses on a single optical communication band. The influence of wavelengths has not been studied. In this paper, we propose a lateral separate absorption multiplication (SAM) APD and conduct an in-depth research into the performance of Ge/Si APDs at different wavelengths. We reveal a significant enhancement in the performance of Ge/Si APDs at L-band (1600 nm) compared to the C-band (1550 nm). A gain-bandwidth product of 279 GHz corresponding to a gain of 18.4 and a bandwidth of 15.2 GHz are achieved at 1600 nm. Through systematic experimental design and theoretical analysis, we evaluate the mechanisms of the higher gain, providing insights into its potential applications in the field of optical communication. This study holds significant implications for expanding the application scope of Ge/Si APDs in optical communication, providing experimental support for their superior performance at higher wavelengths and potentially driving advancements in related technologies.

Improving metrology with quantum scrambling in a spin-1 Bose-Einstein condensate coupled to a cavity

Spinor Bose-Einstein condensate is an ideal candidate for implementing the many-body entanglement, quantum measurement and quantum information processing owing to its inherent spin-mixing dynamics. Here we present a system of an 87Rb atomic spin-1 Bose-Einstein condensate coupled to an optical ring cavity, in which cavity-mediated nonlinear interactions give rise to saddle points in the semiclassical phase space, providing a general mechanism for exponential fast scrambling and metrological gain augment. We theoretically study metrological gain and fidelity out-of-time-ordered correlator based on time-reversal protocols and demonstrate that exponential rapid scrambling dynamics can enhance quantum metrology. In addition, we use the out-of-time-ordered correlator to probe dynamical phase transitions. This work is useful to understand the intrinsic relation between the concepts from different subfields of quantum science.

Origin of Optical Gain in Narrow ZnO Microrods with Whispering Gallery Modes

Due to sufficiently high lasing thresholds, stimulated emission in relatively small ZnO microcrystal lasers is often considered to be fed by an inverted electron–hole plasma (EHP). In this study, the nature of optical gain in such emitters is investigated using ZnO microrods 1–6 µm in diameter synthesized by a modified thermal evaporation method and exhibiting whispering-gallery mode (WGM) lasing in the near ultraviolet range. It is demonstrated that optical gain in these objects is not a consequence of population inversion of the EHP at either low or room temperatures. Instead, the primary gain mechanism is the process of scattering of electron–hole pairs by free electrons. Unlike the case of large ZnO WGM microcavities, in small-diameter microrods this process turns out to be dominant over a wide temperature range.

Spray-lithography of hybrid graphene-perovskite paper-based photodetectors for sustainable electronics

Paper is an ideal substrate for the development of flexible and environmentally sustainable ubiquitous electronic systems. When combined with nanomaterial-based devices, it can be harnessed for various Internet-of-Things applications, ranging from wearable electronics to smart packaging. However, paper remains a challenging substrate for electronics due to its rough and porous nature. In addition, the absence of established fabrication methods is impeding its utilization in wearable applications. Unlike other paper-based electronics with added layers, in this study, we present a scalable spray-lithography on a commercial paper substrate. We present a non-vacuum spray-lithography of chemical vapor deposition (CVD) single-layer graphene (SLG), carbon nanotubes (CNTs) and perovskite quantum dots (QDs) on a paper substrate. This approach combines the advantages of two large-area techniques: CVD and spray-coating. The first technique allows for the growth of SLG, while the second enables the spray coating of a mask to pattern CVD SLG, electrodes (CNTs), and photoactive (QDs) layers. We harness the advantages of perovskite QDs in photodetection, leveraging their strong absorption coefficients. Integrating them with the graphene enhances the photoconductive gain mechanism, leading to high external responsivity. The presented device shows high external responsivity of ∼520 A W−1 at 405 nm at <1 V bias due to the photoconductive gain mechanism. The prepared paper-based photodetectors (PDs) achieve an external responsivity of 520 A W−1 under 405 nm illumination at <1 V operating voltage. To the best of our knowledge, our devices have the highest external responsivity among paper-based PDs. By fabricating arrays of PDs on a paper substrate in the air, this work highlights the potential of this scalable approach for enabling ubiquitous electronics on paper.

High gain NiO/ZnO heterojunction photodiodes operated in Deep-ultraviolet region

Epitaxially matched (0001) Al2O3 single substrates are utilized to design p-n heterojunctions (p-NiO/n-ZnO) as they offer low defect density for device fabrication due to small lattice mismatches. Using the radio frequency sputtering technique, the NiO/ZnO thin film-based heterojunction has been fabricated by varying the n-type film's (ZnO) thickness for ultra-violet (UV) photodiode application. It has been investigated how different ZnO film thicknesses affect junction parameters and photoresponse properties. The high photosensitivity (∼ 104), enhanced current gain (∼ 105) and fast response obtained at very low UV intensity (0.62μW/cm2) at 300 nm wavelength are attributed to the internal gain mechanism (recombination tunnelling and space-charge limited current conduction with the remarkable effect of the presence of excess free oxygen) in these devices. The prepared heterojunction photodiode with high speed and deep-UV sensitivity can be a potential solution for visible blind UV detection.

Voltage-assisted 3D printing of polymer composite dielectric films with low energy loss and high energy storage density

PVDF-based polymers have garnered significant attention in the field of high-power density electrostatic capacitors due to their exceptional dielectric strength. However, their practical applications are constrained by low charge-discharge efficiency (η) and energy storage density (Ue), which stem from high ferroelectric relaxation and low breakdown strength (Eb). Here, a hydrogenated glassy polymer poly(styrene-methyl methacrylate-methylallyl alcohol) (PSMA) is designed and synthesized to be homogeneously distributed in PVDF through voltage-assisted 3D printing-hot pressing, resulting in a flexible composite film. The findings demonstrate that PSMA, rich in hydrogen bonds and high modulus strength, effectively mitigates the ferroelectric phase transition of PVDF to enhance η. Additionally, the voltage-assisted 3D printing process induces an entropy gain mechanism, facilitating the uniform distribution of the two phases and enhancing the interfacial properties for enhancing Eb. Remarkably, the study achieves prominent growth in energy storage performance, with Ue and η reaching 18.1 J/cm3 and 80 % at 525 MV/m, respectively. These remarkable results highlight the potential of 3D printing technology in enhancing the energy storage performance of PVDF-based dielectrics.

Metabolic liability for weight gain in early adulthood

While weight gain is associated with a host of chronic illnesses, efforts in obesity have relied on single "snapshots" of body mass index (BMI) to guide genetic and molecular discovery. Here, we study >2,000 young adults with metabolomics and proteomics to identify a metabolic liability to weight gain in early adulthood. Using longitudinal regression and penalized regression, we identify a metabolic signature for weight liability, associated with a 2.6% (2.0%-3.2%, p= 7.5×10-19) gain in BMI over≈20 years per SD higher score, after comprehensive adjustment. Identified molecules specified mechanisms of weight gain, including hunger and appetite regulation, energy expenditure, gut microbial metabolism, and host interaction with external exposure. Integration of longitudinal and concurrent measures in regression with Mendelian randomization highlights the complexity of metabolic regulation of weight gain, suggesting caution in interpretation of epidemiologic or genetic effect estimates traditionally used in metabolic research.

Mechanisms of Optical Gain in Heavily Doped AlxGa1 – xN:Si Structures (x = 0.56–1)

Mechanisms of Optical Gain in Heavily Doped AlxGa1 – xN:Si Structures (x = 0.56–1)

Optical gain in a degenerate two-level system in the presence of a transverse magnetic field

Here we report a theoretical model that allows magnetically assisted narrowband probe beam amplification in a closed two-level system with triple Zeeman degeneracy. The gain mechanism can be understood in terms of coherent population transfer between the levels of the Zeeman ground state induced by the external magnetic field. The theoretical model we develop here using a simpler atomic transition Fg=1→Fe=0, in agreement with the experimental results already observed in recent literature. Additionally, we validate our theoretical predictions with the results obtained via density matrix numeric calculation and we believe our theoretical results could useful in communication protocols involving distant nodes.

Fabrication and mechanical properties of multi-principal cation (Mg,Ti,Cr,Zr,Al,Si) mullite ceramic

Milti-principal cation oxide ceramics with excellent mechanical properties for potential applications in coating materials. A Multi-principal cation mullite (MPCM) ceramic is synthesized with MgO, TiO2, Cr2O3, ZrCl2O·8H2O and Al2O3, SiO2 via solid state reaction at 1600 °C. It is determined that 96.9 % of the sample composition is mullite. MPCM ceramic exhibits higher compressive strength (981 ± 19 MPa) and fracture toughness (3.37 ± 0.05 MPa∙m1/2), the compressive strength has raised by 453 MPa, and the added value of solution strengthening (452 MPa) is gained by using solid-solution strengthening theory. The improvement of compressive strength is mainly due to the solution strengthening effect of the four oxides(Mg, Ti, Zr, Cr), and the improvement of fracture toughness is caused by the grain hindrance during crack propagation. Moreover, its application at the high-temperature resistant coating is verified through experimentation. The interfacial binding force, as an important mechanical property index for ceramics, is researched. In this study, pure mullite powder and MPCM powder are coated onto the refractory TaWNbV alloy matrix by slurry coating method, and the interfacial toughness of the two coatings mingled with the matrix is calculated to be 72.9 and 62.6 J·m−2, respectively. The “shrinking cylinder” model is introduced to interpret the oxidative weight gain mechanism of the two coatings.

Performances of concrete with binder and/or aggregates replacement by all-solid waste materials

Aiming for an all-solid waste concrete, a quaternary solid waste binder (SWBs) system comprising blast furnace slag, fly ash, desulfurization gypsum, and Bayer red mud was developed and utilized for both binders and preparation of cold bonded artificial aggregates. The first section investigated and discussed the hydration properties and strength gain mechanism of SWBs, revealing that ettringite formation and growth contribute to early age strength development of SWBs, while C-A-S-H formation contributes significantly to the later strength gain. The second section systematically studied the concrete performances, including mechanical properties, shrinkage, chlorides, and seawater resistance. An all-solid waste-based concrete strategy was presented by gradually substituting cement and natural aggregates. It was observed that SWBs-based concrete exhibited significantly lower shrinkage and excellent chloride ion resistance, although slightly lower mechanical properties were observed. The solid waste-based artificial aggregates proved viable alternatives to natural rock aggregates in low-strength concrete classes. Incorporating artificial aggregates endowed the concrete with self-curing properties and reduced its shrinkage and chloride migration, with only a minor effect on its mechanical strength. Lastly, an all-solid waste concrete combining the characteristics of SWBs and cold-bonded artificial aggregates was achieved. The resulting concrete exhibited lower shrinkage and excellent chloride and seawater resistance. This study provides a reference for designing and developing solid waste-based binders and concrete.

Sensitive organic/inorganic polarized photodetectors enhanced by charge transfer with image sensing capacity.

Organic photodetectors (OPDs) have attracted increasing attention in the future wearable sensing and real-time health monitoring, due to their intrinsic features including the mechanical flexibility, low-cost processing and cooling-free operations; while their performances are lagging as the results of inferior carrier mobility and small exciton diffusion coefficient of organic molecules. Graphene exhibits the great photoresponse with wide spectral bandwidth and high response speed. However, weak light absorption and the absence of a gain mechanism have limited its photoresponsivity. Here, we report a sensitive organic/inorganic phototransistor with fast response speed by coupling PTCDA organic single crystal with the monolayer graphene. The long range exciton diffusion in highly ordered π-conjugated molecules, efficient exciton dissociation and charge transfer at the PTCDA/graphene heterointerfaces, and the high mobility of graphene enable a high responsivity (8 × 104A/W), short response time (220 µs) and excellent specific detectivity (>1011 Jones), which is higher than the level of commercial on-chip device. This interfacial photogating effect is verified by the high-resolution spatial photocurrent mapping experiment. In addition, the high sensitivity to polarization is clear and the ultrahigh photoconductive gain enables a near-infrared (NIR) response for 980 and 1550 nm. Finally, high-speed visible and NIR imaging applications are successfully demonstrated. This work suggests that high quality organic single crystal/graphene is a promising platform for future high performance optoelectronic systems and imaging applications.

Incorporation of Empirical Gain and Loss Mechanisms in Open Quantum Systems through Path Integral Lindblad Dynamics.

Path integrals offer a robust approach for simulating open quantum dynamics with advancements transcending initial system size limitations. However, accurately modeling systems governed by mechanisms that do not conserve the number of quantum particles, such as lossy cavity modes, remains a challenge. We present a method to incorporate such empirical source and drain mechanisms within a path integral framework using quantum master equations. This technique facilitates rigorous inclusion of bath degrees of freedom while accommodating empirical time scales via Lindbladian dynamics. Computational costs are primarily driven by the path integral method with minimal overhead from Lindbladian terms. We use it to study exciton transport in a four-site Fenna-Matthews-Olson model, examining the potential loss of the exciton to the reaction center. This path integral Lindblad method promises an enhanced ability to simulate dynamics and will be fundamental to simulation of spectra in diverse quantum processes in open systems.