Small Shift Research Articles

Rational design of a two-photon probe with solvatochromic emission and AIE-activity for lipid droplet specific imaging

Abnormal changes in numbers, sizes and polarities of lipid droplet (LD) are thought to be closely associated with varieties diseases such as fatty liver, diabetes, atherosclerosis and even cancer. However, there still exists some shortcomings of the current commercial LD probes, such as aggregation-caused quenching (ACQ) effect, small Stokes shifts, excitation wavelength restricted to visible light region, and lacking of two-photon excitation fluorescence, which restrict the diagnosis of LD related diseases. Herein, a two-photon aggregation-induced emission (AIE) bioprobe, namely TP-LDP, was rationally designed by constructing of the donor-acceptor-donor (D-A-D) structure for specific imaging of LD. TP-LDP exhibited AIE-activities, solvatochromic emissions (λemmax: 451–652 nm), extra-large Stokes shifts (11550 cm−1) as well as two-photon absorption ability (156 GM). More importantly, cellular experiments demonstrated that TP-LDP possessed excellent photostability, nice two-photon excited fluorescence imaging ability as well as precise LD-targeting, and successfully detected abnormal LD proliferations in living cells. These features enable TP-LDP to effectively compensate for the shortcomings of commercial LD dyes and have the potential to become a powerful tool for detecting LD related diseases.

Small Stokes shift and high thermostability in Ce3+ doped K2BaPO4F phosphors

Novel K2BaPO4F:Ce3+ phosphors with strong violet-emission and high thermostability were synthesized by a traditional high-temperature solid-state reaction method. The phase composition and crystal structure were investigated in detail by XRD refinement. DFT calculations based on refined crystal structure were performed. A bright emission in the range of 340–390 nm with a small Stokes shift has been observed when excited at about 323 nm in K2BaPO4F:Ce3+ phosphors. The temperature-dependent PL spectra from 80 to 500 K were investigated systematically. The best doping concentration of K2BaPO4F:xCe3+ phosphors was verified and the concentration quenching mechanism was also confirmed. When the temperature increased from 80 K to 500 K, the emission intensity still remains 53 %. The thermal quenching mechanism was explained using the crystal structure investigation and DFT calculation. The strong near-ultraviolet emission intensity and ultra-high thermal stability indicating that the prepared K2BaPO4F:Ce3+ phosphors have potential applications in anti-counterfeiting and solid-state lighting.

Solid‐State Absorption, Luminescence, and Singlet Fission of Furanyl‐Substituted Diketopyrrolopyrroles with Different π‐Stacking Arrangements

AbstractSmall modifications of the diketopyrrolopyrrole (DPP) molecular structure induced remarkable changes in its spectral and photophysical behavior. Using furan (F) heterosubstitution instead of thiophene (T) substituent resulted in a small blue shift and decreased Huang‐Rhys factor of the absorption spectra in solution, irrespectively to N,N'‐alkyls. Branching of alkyl side chains by formal 2‐ethylation of n‐hexyl substituent (C6 to EH) switched the slipped‐stack arrangement, irrespectively on the heteroatoms. Consequent changes in steady‐state absorption spectra of thin films were interpreted using time dependent density functional theory calculations, carried out on model dimers. Solid‐state luminescence is weak and partially dependent on an excitation wavelength. Singlet fission was observed by femtosecond transient absorption spectroscopy, with considerably different yields for variously π‐stacked FDPP‐EH (30 %) and FDPP‐C6 (160 %). The shape of triplet‐triplet absorption spectra was also influenced by various π‐stacking. The results are discussed in terms of different mixing of both Frenkel and charge transfer states in model dimers and different excitonic and electronic coupling in both types of π‐stacks, visualized by natural transition orbitals.

Influence of Gate Depletion Layer Width on Radiation Resistance of Silicon Carbide Junction Field-Effect Transistors

Silicon carbide junction field-effect transistors (SiC JFETs) are promising candidates as devices applicable to radiation conditions, such as the decommissioning of nuclear facilities or the space environment. We investigate the origin of the threshold volage (Vth) shift and hysteresis of differently structured SiC JFETs. A large positive Vth shift and hysteresis are observed for a depletion-type JFET with a larger depletion layer width. With changing the sweep range of the gate voltage and depletion width, the Vth shift was positively proportional to the difference between the channel depth and depletion width (channel depth–gate depletion width). By illuminating the sub-band gap light, the Vth of the irradiated depletion JFETs recovers close to nonirradiated ones, while a smaller shift and hysteresis are observed for the enhancement type with a narrower width. It can be interpreted that positive charges generated in a gate depletion layer cause a positive Vth shift. When they are swept out from the depletion layer and trapped in the channel, this gives rise to a further Vth shift and hysteresis in gamma-irradiated SiC JFETs.

417 W, 2.38 mJ Innoslab amplifier compressible to a high pulse quality of 406 fs.

We demonstrate a 417 W, 175 kHz Innoslab chirped pulse amplification laser compressible to short and clean 406 fs pulse duration. A spectral bandwidth (full width at half maximum, FWHM) of ∼3 nm was maintained at full pump power, and the pulses exhibited good pulse quality in a wide tunable pulse energy range from 1.7 mJ to a maximum of 2.38 mJ. At the maximum output power, the compressed pulses were nearly pedestal free. The comprehensive effects of residual high-order dispersion from the front end, the gain shaping effects of the amplifier, and the slight mismatch of third-order dispersion (TOD) between the stretcher (CFBG) and the gating compressor, along with the small nonlinear phase shift accumulated in the amplifier, could have facilitated the high pulse quality. To the best of our knowledge, this is the shortest pulse duration from the Innoslab amplifiers at hundreds of watts average power in the millijoule energy regime.

Rational Design of Tunable Near-Infrared Oxazine Probe with Large Stokes Shift for Leucine Aminopeptidase Detection and Imaging.

Near-Infrared (NIR) fluorescence imaging with the advantages of deep tissue penetration and minimum background, has been widely employed and developed in the study of biological applications. However, small Stokes shifts, difficulty in optical tuning, and pH sensitivity are still the major limitations faced by current NIR dyes. To solve these problems, we rationally designed a pH insensitive amino-tunable NIR oxazine fluorophore DQF-NH2 , which exhibited large Stokes shift (125 nm) accompanied with NIR excitation/emission due to the introduction an asymmetrical alternating vibronic feature. By benefiting from the excellent photophysical properties of DQF-NH2 , we have successfully constructed the probe DQF-NH2 -LAP with the ability to detect endogenous LAP. Bioimaging assays demonstrated that DQF-NH2 -LAP can not only effectively detect LAP in living cells, but also was successfully applied to image tumor tissue in vivo. We anticipate that the functionalizable dye DQF-NH2 may be a potential new NIR dye platform with an optically tunable group for the development of future desirable probes for bioimaging.

Source-Free Domain Adaptation via Target Prediction Distribution Searching

Existing Source-Free Domain Adaptation (SFDA) methods typically adopt the feature distribution alignment paradigm via mining auxiliary information (eg., pseudo-labelling, source domain data generation). However, they are largely limited due to that the auxiliary information is usually error-prone whilst lacking effective error-mitigation mechanisms. To overcome this fundamental limitation, in this paper we propose a novel Target Prediction Distribution Searching (TPDS) paradigm. Theoretically, we prove that in case of sufficient small distribution shift, the domain transfer error could be well bounded. To satisfy this condition, we introduce a flow of proxy distributions that facilitates the bridging of typically large distribution shift from the source domain to the target domain. This results in a progressive searching on the geodesic path where adjacent proxy distributions are regularized to have small shift so that the overall errors can be minimized. To account for the sequential correlation between proxy distributions, we develop a new pairwise alignment with category consistency algorithm for minimizing the adaptation errors. Specifically, a manifold geometry guided cross-distribution neighbour search is designed to detect the data pairs supporting the Wasserstein distance based shift measurement. Mutual information maximization is then adopted over these pairs for shift regularization. Extensive experiments on five challenging SFDA benchmarks show that our TPDS achieves new state-of-the-art performance. The code and datasets are available at https://github.com/tntek/TPDS.

Electronic and vibrational spectroscopies of aromatic clusters with He in a supersonic jet: The case of neutral and cationic phenol-Hen (n = 1 and 2).

Van der Waals clusters composed of He and aromatic molecules provide fundamental information about intermolecular interactions in weakly bound systems. In this study, phenol-helium clusters (PhOH-Hen with n ≤ 2) are characterized for the first time by UV and IR spectroscopies. The S1 ← S0 origin and ionization energy both show small but additive shifts, suggesting π-bound structures of these clusters, a conclusion supported by rotational contour analyses of the S1 origin bands. The OH stretching vibrations of the PhOH moiety in the clusters match with those of bare PhOH in both the S0 and D0 states, illustrating the negligible perturbation of the He atoms on the molecular vibration. Matrix shifts induced by He attachment are discussed based on the observed band positions with the help of complementary quantum chemical calculations. For comparison, the UV and ionization spectra of PhOH-Ne are reported as well.

Efficient Monitoring of a Parameter of Non-Normal Process Using a Robust Efficient Control Chart: A Comparative Study

The control chart is a fundamental tool in statistical process control (SPC), widely employed in manufacturing and construction industries for process monitoring with the primary objective of maintaining quality standards and improving operational efficiency. Control charts play a crucial role in identifying special cause variations and guiding the process back to statistical control. While Shewhart control charts excel at detecting significant shifts, EWMA and CUSUM charts are better suited for detecting smaller to moderate shifts. However, the effectiveness of all these control charts is compromised when the underlying distribution deviates from normality. In response to this challenge, this study introduces a robust mixed EWMA-CUSUM control chart tailored for monitoring processes characterized via symmetric but non-normal distributions. The key innovation of the proposed approach lies in the integration of a robust estimator, based on order statistics, that leverages the generalized least square (GLS) technique developed by Lloyd. This integration enhances the chart’s robustness and minimizes estimator variance, even in the presence of non-normality. To demonstrate the effectiveness of the proposed control chart, a comprehensive comparison is conducted with several well-known control charts. Results of the study clearly show that the proposed chart exhibits superior sensitivity to small and moderate shifts in process parameters when compared to its predecessors. Through a compelling illustrative example, a real-life application of the enhanced performance of the proposed control chart is provided in comparison to existing alternatives.

Shifting decision thresholds can undermine the probative value and legal utility of forensic pattern-matching evidence

Forensic pattern analysis requires examiners to compare the patterns of items such as fingerprints or tool marks to assess whether they have a common source. This article uses signal detection theory to model examiners' reported conclusions (e.g., identification, inconclusive, or exclusion), focusing on the connection between the examiner's decision threshold and the probative value of the forensic evidence. It uses a Bayesian network model to explore how shifts in decision thresholds may affect rates and ratios of true and false convictions in a hypothetical legal system. It demonstrates that small shifts in decision thresholds, which may arise from contextual bias, can dramatically affect the value of forensic pattern-matching evidence and its utility in the legal system.

Hyperparasitism and the evolution of parasite virulence.

Hyperparasites (species which parasitize other parasites) are common in natural populations, affecting many parasitic taxa, including: eukaryotic parasites; bacterial and fungal pathogens. Hyperparasitism is therefore likely to shape the ecology and evolution of many host-parasite systems, representing a promising method for biocontrol (e.g., treating antimicrobial resistant infections). However, the eco-evolutionary consequences of hyperparasitism have received little attention. We use a host-parasite-hyperparasite model to explore how introducing a hyperparasite drives the evolution of parasite virulence, and what impact this has on the host population. We show when the introduction of a hyperparasite selects for higher or lower parasite virulence, and the changes in virulence experienced by the host population. Crucially, we show that variation in the direct effects of hyperparasites on virulence and transmission, and the probability of cotransmission, can lead to a previously unseen hysteresis effect, whereby small shifts in hyperparasite characteristics can lead to sudden shifts in parasite virulence. We also show that hyperparasites can induce diversification in parasite virulence, leading to the coexistence of high and low virulence strains. Our results show hyperparasites can have dramatic effects on the evolution of parasite virulence, and that the use of hyperparasites in biocontrol should be approached with caution.

Adaptive protocols for SU(1,1) interferometers to achieve ab initio phase estimation at the Heisenberg limit

The precision of phase estimation with interferometers can be greatly enhanced using non-classical quantum states, and the SU(1,1) interferometer is an elegant scheme, which generates two-mode squeezed state internally and also amplifies the signal. It has been shown in Anderson et al (2017 Phys. Rev. A 95 063843) that the photon-number measurement can achieve the Heisenberg limit, but only for estimating a small phase shift. We relax the constraint on the range of phase by considering two adaptive protocols: one also uses the photon-number measurement with a specially tuned sequence of feedback phase; the other implements the yet-to-be-realized optimal measurement but without fine tuning.

ARL Evaluation of a DEWMA Control Chart for Autocorrelated Data: A Case Study on Prices of Major Industrial Commodities

The double exponentially weighted moving average (DEWMA) control chart, an extension of the EWMA control chart, is a useful statistical process control tool for detecting small shift sizes in the mean of processes with either independent or autocorrelated observations. In this study, we derived explicit formulas to compute the average run length (ARL) for a moving average of order q (MA(q)) process with exponential white noise running on a DEWMA control chart and verified their accuracy by comparison with the numerical integral equation (NIE) method. The results for both were in good agreement with the actual ARL. To investigate the efficiency of the proposed procedure on the DEWMA control chart, a performance comparison between it and the standard and modified EWMA control charts was also conducted to determine which provided the smallest out-of-control ARL value for several scenarios involving MA(q) processes. It was found that the DEWMA control chart provided the lowest out-of-control ARL for all cases of varying the exponential smoothing parameter and shift size values. To illustrate the efficacy of the proposed methodology, the presented approach was applied to datasets of the prices of several major industrial commodities in Thailand. The findings show that the DEWMA procedure performed well in almost all of the scenarios tested. Doi: 10.28991/ESJ-2023-07-05-020 Full Text: PDF

Efficient signed-rank based EWMA and HWMA repetitive control charts for monitoring process mean with and without auxiliary information

Control charts are powerful tools to observe the presentation of the manufacturing process. Mostly, when the data in industries come from the process may follow non-normal or unknown distributions. So, the distribution-free control charts are useful in practice when the possibility model of the process productivity is unknown. In such situations, the correct selection of the sampling mechanism is beneficial for process examination. This paper proposes a nonparametric exponentially weighted moving average signed-rank (EWMA-SR) and also proposed a homogeneously weighted moving average Signed-Rank (HWMA-SR) control charts for examining the small shift in process with the help of an auxiliary variable (in the form of a regression estimator) by using an efficient plan, namely, a repetitive sampling plan. The proposal’s presentation is evaluated and matched with its complements for different symmetric distributions by using some famous run length properties including average run length, median run length, and standard deviation of run length.

Optimizing graded metamaterials via genetic algorithm to control energy transmission

Optimization of functionally graded metamaterial arrays with a high dimensional and continuous geometric design space is cumbersome and could be accelerated via machine learning tools. Mechanical metamaterials can manipulate acoustic or ultrasonic waves by introducing significant dispersive and attenuative effects near their natural frequency. In this work, functionally graded structures are designed and optimized to combine the energy attenuation performance of multiple unit cells with varying frequency responses and to reduce the interlayer mismatch effects. Optimization through genetic algorithms avoids many local minima related to high dimensionality of the design space, but requires many iterations. A reduced order model (ROM) is applied, which can reproduce the transmission response traditionally calculated with FEM in a fraction of the time. Pairing GA and the ROM together, an array of 6 unit cells (with a total of 18 independent geometric design variables) is optimized to have stop bands with extended width and sharper boundaries. Symmetric functionally graded structures are determined to have optimal geometric configurations. Measured 3D printed features are projected onto the ROM solutions to quantify the effect of printing uncertainty on array performance. Repeatability error of ±20μm is determined to reduce the mean depth of the transmission stop band by a factor of 102 and introduce small shifts in center frequency and band width. Proposed methods to improve the resolution of accessible points in the ROM space, reduce sensitivity to geometric uncertainty, and add design freedom include introducing out-of-plane perforations and varying constituent materials using tunable filled resin systems.

Triple exponentially weighted moving average control charts without or with variable sampling interval for monitoring the coefficient of variation

The coefficient of variation (CV) chart is widely used in the process where the standard deviation is proportional to the mean. In this work, two separate one-sided triple exponentially weighted moving average control charts are proposed to monitor the CV squared (denoted as TEWMA- γ 2 chart). By adding the variable sampling interval (VSI) feature to the proposed - γ 2 charts, the VSI TEWMA- γ 2 charts are further proposed to improve the performance of the TEWMA- γ 2 charts. Through extensive Monte Carlo simulations, the zero-state and steady-state run length (RL) performances are presented. The comparisons with the existing CV charts, based on several run length metrics show the superiority of the proposed charts, especially for small shifts. Moreover, the overall measure, expected ARL (EARL), also shows the outperformance of the γ 2 charts. In addition, based on the average time to signal (ATS) and adjusted ATS (AATS), it is shown that the VSI strategy makes the TEWMA- γ 2 charts detect the shifts more quickly. An illustrative example from the sintering process is finally provided to display the application of the proposed charts.

Rational Design of Cost-Effective 4-Styrylcoumarin Fluorescent Derivatives for Biomolecule Labeling.

Fluorescent labels are key tools in a wide range of modern scientific applications, such as fluorescence microscopy, flow cytometry, histochemistry, direct and indirect immunochemistry, and fluorescence in situ hybridization (FISH). Small fluorescent labels have important practical advantages as they allow maximizing the fluorescence signal by binding multiple fluorophores to a single biomolecule. At present, the most widely used fluorescent labels available present small Stokes shifts and are too costly to be used in routine applications. In this work we present four new coumarin derivatives, as promising and inexpensive fluorescent labels for biomolecules, obtained through a cost-effective, efficient, and straightforward synthetic strategy. Density functional theory and time-dependent density functional theory calculations of the electronic ground and lowest-lying singlet excited states were carried out in order to gain insights into the observed photophysical properties.

Q-Carbon as a Corrosion-Resistant Coating.

A newly discovered quenched form of carbon, widely known as Q-carbon, thin films are synthesized by the direct conversion of the amorphous carbon layer using the nanosecond pulsed laser annealing technique, and its corrosion-resistant properties, that is, potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy technique, are investigated. The unique microstructure and the existence of defects (sp2 content) in sp3-rich Q-carbon are highly desirable for efficient corrosion-resistant performance. The sp3 percentage of the as-grown Q-carbon is measured to be ∼80.5% from the D and G peaks of the Raman and C-1S X-ray photoelectron spectrum. The anti-corrosion properties with inhibition durability of Q-carbon thin films are systematically investigated in various concentrations of Na2SO4 solutions, and the corrosion potential, corrosion current, and corrosion rate of Q-carbon are determined to be -253 V, 30.1 × 10-5 A/cm2, and 0.00528, respectively, for 1 M Na2SO4 solution. Both series and contact resistance decrease from 5498.6 and 821.1 Ω to 698.8 and 124.3 Ω with an increase of Na2SO4 concentration from 0.1 to 1 M, respectively. The small shift of PDP curves toward more negative potential, the shrinkage of the radius of semicircular arcs in the Nyquist plot (Z″ vs Z'), and negligible loss in corrosion resistance (∼78%) are observed for Q-carbon thin film at the immersion time up to 48 h. The unique sp2-sp3 ratio, shorter bond length, compact atomic arrangement, and minimum porosity, along with the high adhesion strength, due to the ultrafast solid-liquid-solid growth route, of Q-carbon thin film on the substrate signify it as a better alternative compared to the existing corrosion-resistant materials.

Acoustic trauma increases inhibitory effects of amygdala electrical stimulation on thalamic neurons in a rat model

Acoustic trauma (AT) induced hearing loss elicits plasticity throughout the central auditory pathway, including at the level of the medial geniculate nucleus (MGN). Hearing loss also results in altered neuronal responses in the amygdala, which is involved in sensory gating at the level of the MGN. However, whether these altered responses in the amygdala affect sensory gating at the level of the MGN requires further evaluation. The current study aimed to investigate the effects of AT-induced hearing loss on the functional connectivity between the amygdala and the MGN. Male Sprague–Dawley rats were exposed to either sham (n = 5; no sound) or AT (n = 6; 16 kHz, 1 h, 124 dB SPL) under full anaesthesia. Auditory brainstem response (ABR) recordings were made to determine hearing thresholds. Two weeks post-exposure, extracellular recordings were used to assess the effect of electrical stimulation of the amygdala on tone-evoked (sham n = 22; AT n = 30) and spontaneous (sham n = 21; AT n = 29) activity of single neurons in the MGN. AT caused a large temporary and small permanent ABR threshold shift. Electrical stimulation of the amygdala induced differential effects (excitatory, inhibitory, or no effect) on both tone-evoked and spontaneous activity. In tone-evoked activity, electrical stimulation at 300 µA, maximum current, caused a significantly larger reduction in firing rate in AT animals compared to sham, due to an increase in the magnitude of inhibitory effects. In spontaneous activity, there was also a significantly larger magnitude of inhibitory effects following AT. The findings confirm that activation of the amygdala results in changes in MGN neuronal activity, and suggest the functional connectivity between the amygdala and the MGN is significantly altered following AT and subsequent hearing loss.

The Design and Investigation of a Super Wideband Antenna with Dual-Band Notch Characteristics for MIMO Application

A printed monopole super wideband (SWB) antenna is presented in this paper. It consists of a beveled-shaped radiator and a tapered ground plane. It is investigated that tapering of the radiator and ground plane enhances the impedance matching and results in broad impedance bandwidth. The experimental result depicts that the antenna achieved 164.9% impedance bandwidth from 2.6 to 27.27 GHz. Furthermore, to prevent the interference caused by communication systems within the ultra-wideband (UWB) range, dual-band rejection at Wi-MAX (2.7–4 GHz). and X-band (8.5–12 GHz) are introduced by etching an H-shape and two back-to-back C-shaped notches in the radiator and feedline, respectively. The measured result demonstrates that both slots effectively reject the desired frequency bands with a small shift in the lower frequency edge from 2.41 to 2.6 GHz. In addition, the proposed antenna application is shown in the two elements MIMO system where a bowtie decoupling structure is utilized to improve the isolation. It is found that the presence of a decoupling structure improves the isolation by up to 60%. To characterize the diversity performance, parameters such as Diversity Gain (DG), Envelop Correlation Coefficient (ECC), Channel Capacity Loss (CCL), and Mean Effective Gain (MEG) are calculated and all are found in the acceptable limit.