Shift Of Spectrum Research Articles

Nonlinear enhanced mass sensor based on optomechanical system

Abstract A high-precision and tunable mass detection scheme based on a double-oscillator optomechanical system is proposed. By designating one of the oscillators as the detection port, tiny mass signals can be probed through the frequency shift of the output spectrum, utilizing the system's optomechanically induced transparency (OMIT) effect. By solving the output of the optical mode, we demonstrate that the system exhibits two OMIT windows due to the double oscillator coupling, with one window being strongly dependent on the mass to be detected. Characterizing the spectrum around this window enables high magnification and precise detection of the input signal under nonlinear parameter conditions. Additionally, our scheme shows resilience to environmental temperature variations and drive strength perturbations.

Kernel-inspired algorithm to transform transmission electron microscopy images into discrete dipole approximation geometries

In this work, we present a code that transforms 2D transmission electron microscopy images into 3D geometries for discrete dipole approximation simulations in DDSCAT 7.3.3 based on Python 3.11 and OpenCV 4.8.1. This allows for the extrapolation of experimental sample images into ready-to-use simulation geometries. The advantage is that the geometry reflects complex shapes instead of approximations of basic shapes like spheres, cylinders, or cubes. The underlying algorithm to extrapolate 2D images to 3D structures is inspired by the working principle of kernels used in image processing. To showcase the code, the absorption spectrum of deposited gold nanoparticles was simulated and compared with experimental values. Apart from a small systematic shift of the simulated spectrum, it is in excellent agreement with the experiment.

Strong noninertial radiative shifts in atomic spectra at low accelerations

Despite numerous proposals investigating various properties of accelerated detectors in different settings, detecting the Unruh effect remains challenging due to the typically weak signal at achievable accelerations. For an atom with frequency gap ω0, accelerated in free space, significant acceleration-induced modification of properties like transition rates and radiative energy shifts requires accelerations of the order of ω0c. In this paper, we make the case for a suitably modified density of field states to be complemented by a judicious selection of the system property to be monitored. We study the radiative energy-level shift in inertial and uniformly accelerated atoms coupled to a massless quantum scalar field inside a cylindrical cavity. Uniformly accelerated atoms experience thermal correlations in the inertial vacuum, and the radiative shifts are expected to respond accordingly. We show that the noninertial contribution to the energy shift can be isolated and significantly enhanced relative to the inertial contribution by suitably modifying the density of field modes inside a cylindrical cavity. Moreover, we demonstrate that monitoring the radiative energy shift, as compared to transition rates, allows us to reap a stronger purely noninertial signal. We find that a purely noninertial radiative shift as large as 50 times the inertial energy shift can be obtained at small, experimentally achievable accelerations (a∼10−9ω0c) if the cavity’s radius R is specified with a relative precision of δR/R0∼10−7. Given that radiative shifts for inertial atoms have already been measured with high accuracy, we argue that the radiative energy-level shift is a promising observable for detecting Unruh thermality with current technology. Published by the American Physical Society 2024

Phyto-mediated biosynthesis of silver nanoparticles using Aloe barbadensis Miller leaves gel with improved antibacterial, anti-fungal, antioxidant, anti-inflammatory, anti-diabetic, and anti-cancer activities

An effective topical therapeutic agent requires a multifunctional attribute such as antibacterial, antioxidant, and anti-inflammatory efficacy. The green-synthesized metallic and metallic oxide nanoparticles have shown significant applicability in this regard. Hence a biosynthesis of silver nanoparticles (AgNPs) using Aloe barbadensis miller leaf gel was fabricated and evaluated for effect of imperative influences such as temperature, time, and concentration of reactant on AgNPs synthesis. Furthermore, the biomimetic qualities were assessed to ensure the safety and efficacy. The synthesis of stabilized and capped AgNPs presented a UV–vis–based plasmonic resonance at ∼ 400 nm. The reduction of silver nitrate was further confirmed by the shift in FTIR spectra for -OH around 2870 cm−1. SEM and TEM images revealed cubic shape of the AgNPs. Whereas X-ray diffraction pattern indicated crystalline structure (crystallite size of ∼ 31.14 nm) with an inter-planar spacing value of 2.77, 1.96, and 1.67 Å for (200), (220), and (311) planes, respectively. In addition, AgNPs indicated a steady dispersion, homogeneity, and strong anionic zeta potential (∼ 35.4 mV). The results of antibacterial and antifungal activity demonstrated the potential of phyto-synthesized AgNPs in mitigation of infection associated with tested bacterial strain Bacillus subtilis, Bacillus megaterium, Shigella flexneri, Trichoderma viride, Aspergillus niger, and Penicillium crysogenum. Moreover, the results of hydrogen peroxide-based scavenging, anti-inflammatory, and anti-diabetic study revealed that the biosynthesized AgNPs exhibit an improved biomimetic attribute. Additionally, the biocompatibility assay demonstrated > 80 % of CaCO-2 and L-929 cells viability at 1.67 μg/mL and 3.35 μg/mL, respectively. The anticancer activity of synthesized AgNPs against epithelium-like phenotype oral squamous carcinoma cells (CLS-354/WT) displayed IC50 of 11.58 μg/mL. The results indicate that biogenic produced AgNPs may find suitable use as a potential therapeutic agent due to multifunctional attribute.

A dual-channel fluorescent probe based on salamo-Cu(II) complex for sensitive detection of S2- in river and tap water

A new double-salamo-type tetranuclear copper complex [Cu4(L)2](ClO4)2.2CH2Cl2 was designed and prepared, in which the metal atoms in the complex crystals have two different coordination systems, forming a symmetric structure as a whole. As a complex probe molecule, the addition of S2- in solution can achieve a red shift in the fluorescence spectrum, revealing bright green fluorescence, colorimetric and fluorescent dual-channel specific recognition ability and excellent anti-interference ability. The probe can be used to detect S2- by adding acidic and alkaline solutions to adjust the pH of the system for several cycles, which is suitable for ion recognition in most organisms and environments under pH conditions. The working mechanism of S2-recognition by Cu–ZTS was determined to be a synergistic action of ESIPT effect and ICT effect by correlation spectroscopy experiments, HR-MS and XPS tests, and this conclusion was subsequently further verified using theoretical calculations. Finally, the probe molecule showed good practical application value, and the portable test strips were prepared to qualitatively detect the ions, and by testing four different water samples, it was shown that the quantitative recognition of S2- could be realized almost without interference in real water samples. It proves that the coordination probe molecule has good prospects for practical application.

Spin-wave mode coupling in the presence of the demagnetizing field in cobalt-permalloy magnonic crystals

We present the results of studies on the non-uniform frequency shift of spin wave spectrum in a two-dimensional magnonic crystal of cobalt/permalloy under the influence of external magnetic field changes. We investigate the phenomenon of coupling of modes and, as a consequence, their hybridization. By taking advantage of the fact that compressing the crystal structure along the direction of the external magnetic field leads to an enhancement of the demagnetizing field, we analyse its effect on the frequency shift of individual modes depending on their concentration in Co. We show that the consequence of this enhancement is a shift in the coupling of modes towards higher magnetic fields. This provides a potential opportunity to design which pairs of modes and in what range of fields hybridization will occur.

NiO/MWCNT incorporated methyl ammonium lead iodide for an efficient perovskite solar cells

The perovskite solar cells (PSCs) reveal the impressive performance due to the extraordinary characteristic features of perovskite material and its fabrication methods. The complex deposition process and hygroscopic nature of hole transport materials are biggest obstacles for attaining high power conversion efficiency (PCE) with long term stability in PSC. In this study, NiO/MWCNT nanocomposites have been synthesized by hydrothermal method and are incorporated in CH3NH3PbI3 to increase the performance of PSCs with stability. The incorporation has been carried out to improve the properties of CH3NH3PbI3 such as formation of large grain size/grain boundaries, reduce the defects that enhance the charge generation/collection and reduction in recombination. The fabricated PSCs with NiO/MWCNT revealed a PCE of 14.93 % with moderate hysteresis, which is significantly higher PCE than that of pristine PSC. The enhanced recombination resistance was observed by electrochemical impedance spectroscopy, which evinces the remarkable PCE of NiO/MWCNT incorporated PSC. The strong PL quenching and red shift of PL spectrum confirms the low recombination and larger grains in the NiO/MWCNT-CH3NH3PbI3 layer. Moreover, the NiO/MWCNT incorporated PSC retains 94 % of its initial PCE after 600 h of aging under atmospheric condition whereas the PCE of pristine PSC shows 87 % of its initial PCE value. The carbon back electrode also supports to lift up PCE and stability of PSCs.

Multi-cation doped CuCrO[formula omitted] crystallite matrix: Exploring bandgap tunability through Ni-Zn and Ni-Zn-Mg doping for optoelectronic application

Bandgap tuning is a key approach to optimizing materials for advanced technologies, enabling the development of more efficient and specialized devices. In this study, we demonstrate the tunability of the bandgap of CuCrO2 from 2.38 to 4.37 eV via single cation-doping with Ni and Zn, and multi-cation doping with Ni-Zn and Ni-Zn-Mg. XRD analysis reveals structural changes due to lattice distortions by cationic substitution, while FESEM shows the impact of doping on particle size, surface morphology, and crystallinity. The lamellar structure observed with multi-cation doping in FESEM investigations indicates increased structural disorder and defects, causing tailing above the valence band and below the conduction band, significantly reducing the bandgap. The effect of Zn-Ni doping on the lattice is reversed with Mg2+ insertion due to p-p orbital interactions between Mg2+-O, replacing the d-p interaction in the Cr3＋-O bond, as confirmed by optical studies. UV–Vis and photoluminescence analyses reveal significant shifts in bandgaps and emission spectra, with Ni doping yielding a bandgap of 3.97 eV, Zn doping 3.16 eV, Zn-Ni doping expanding it to 4.37 eV, and Zn-Ni-Mg doping reducing it to 2.38 eV. The dopants also affect emission characteristics, including band edge and deep-level emissions. This study provides valuable insights into the relationship between cationic doping and material properties, guiding the design of CuCrO2-based materials with tailored functionalities.

Neutron imaging of the deuterium-tritium tamping gas volume in an inertial confinement fusion hohlraum.

To benchmark the accuracy of the models and improve the predictive capability of future experiments, the National Ignition Facility requires measurements of the physical conditions inside inertial confinement fusion hohlraums. The ion temperature and bulk motion velocity of the gas-filled regions of the hohlraum can be obtained by replacing the helium tamping gas in the hohlraum with deuterium-tritium (DT) gas and measuring the Doppler broadening and Doppler shift of the neutron spectrum produced by nuclear reactions in the hohlraum. To understand the spatial distribution of the neutron production inside the hohlraum, we have developed a new penumbral neutron imager with a 12mm diameter field of view using a simple tungsten alloy spindle. We performed the first experiment using this imager on a DT gas-filled hohlraum and successfully obtained the spatial distribution of neutron production in the hohlraum plasma. We will report on the design of the spindle, characterization of the detectors, and methodology of the image reconstruction.

Polarization-maintaining fiber based macehead shaped interferometric sensor for accurate measurement of refractive index and temperature

A macehead-shaped bent polarization-maintaining fiber-based interferometric sensing structure called MBPIS is described and experimentally demonstrated for precise temperature and refractive index measurement. The sensor’s working principle is explained by simulating the spatial distribution of the field intensity in straight and bending PANDA fibers. A maximum extinction ratio (∼21 dBm) for the interference dip wavelength (1527.825 nm) in the sensor’s output spectrum was optimized by manipulating the birefringence of propagating fiber modes by adjusting PMF’s bending diameter from 17 to 11 mm. The phase difference changes between these fiber modes due to temperature and RI-induced birefringence cause a shift in the interference spectrum. The sensor’s highest RI sensitivity has been seen at −259.32 nm/RIU for a wide range of analytes from 1.3333 to 1.3579. In contrast, the highest temperature sensitivities evaluated for the temperature range of 0 ∼ 100 ℃ are −220 pm/℃ and −0.139 dBm/℃, respectively.

Simultaneous production of singlet oxygen and superoxide anion by thiocarbonyl coumarin for photodynamic therapy

Photodynamic therapy (PDT) is a medical treatment that kills target cells through reactive oxygen species (ROS) generated by photosensitizers (PS) and surrounding oxygen under the stimulus of light. Despite of its popularity in cancer treatment, PDT relys on oxygen and therefore suffers from long response time and low efficiency under low-oxygen situations such as tumor hypoxia. Herein, to improve the usage of oxygen and increase ROS yield, we synthesized six potential PSs termed DC-O, DC-S, DC-BrO, DC-BrS, DC-IO, and DC-IS, by modifying coumarins with thiocarbonyl and bromine/iodine. We found that the thiocarbonyl group induces a significant bathochromic shift of the absorption spectra. In addition, the ROS production was significantly improved, likely because these PSs can simultaneously generate singlet oxygen (1O2) and superoxide anions (O2•−) through different pathways. Among these compounds, DC-BrS produces largest amount of ROS and exhibits strongest cytotoxicity towards cells, the survival rate of B16-F10 cells incubated with DC-BrS was only 20.7 % after irradiation at 460 nm for 10 min, indicating DC-BrS as a strong candidate for photodynamic therapy. Most importantly, this work provides an important direction for the design of PSs in the future.

Analysis of NCM concentration and extraction efficiency in the lithium-ion battery extraction process

In recent years, with the increasing popularity of portable electronic devices (PEDs) and electric vehicles (EVs), the demand for lithium-ion batteries (LIBs) has continued to expand; however, the supply of raw materials such as nickel cobalt, and manganese (NCM) is limited, and it is essential to develop efficient recycling technologies. Hydrometallurgical methods, particularly extraction processes, can be used to obtain high-grade recycled LIB products with proper control of the process window. This study focused on the separation of NCM from copper (Cu) and aluminum (Al) by diluting the metal concentrations ([Me]) and adjusting the pH (using NH4OH) during extraction. For metal composition analysis, in addition to using inductively coupled plasma mass spectrometry (ICP-MS), ultraviolet–visible (UV–Vis) spectroscopy and colorimetric analysis were also employed to monitor ion concentrations. The change in solution color is directly related to the nickel (Ni) and cobalt (Co) ion concentrations. Moreover, a continuous shift in the Ni ion absorption spectra at different pH values did not occur for the Co ion absorption spectra. According to the extraction efficiency (EE%) results, the lower [Me] resulted in the higher EE% of NCM. The optimal process window was established within the range of 0.025–0.1 M and pH = 6.5–7.4.

Structure regulation and luminescence improvement of Gd3Ga5O12:Cr3+: An anti-thermal quenching NIR phosphor for multifunctional applications

Near-infrared (NIR) phosphors converted light emitting diodes (LEDs) are booming as next NIR light sources. But the quantum efficiency and thermal stability of the NIR phosphors need to be improved. Here, thermally stable garnet Gd3Ga5O12 is selected as the matrix and Cr3+ as the luminescent center to obtain Gd3Ga5O12:Cr3+ NIR phosphor. Equivalent smaller Lu3+ was adopted to regulate the structure of Gd3Ga5O12 to further improve the luminescence performance. By regulating the structure the emission spectra shift toward blue region and the intensity is improved. Optimized GdLu2Ga5O12:Cr3+ exhibits anti-thermal quenching behavior and the internal quantum efficiency reaches 73.69 %. Relative sensitivity value of the phosphor GdLu2Ga5O12:Cr3+ reaches 3.353 % K−1 at 423 K based on lifetime mode. LED device is fabricated by combining the phosphor GdLu2Ga5O12:Cr3+ and the commercial red phosphor with blue chip. Electroluminescence spectrum can cover the absorption spectra of the plant dyes well. The lettuce grow faster by adopting this LED device as compensating light source. This work provides an anti-thermal quenching NIR phosphor for multiple applications.

Both edge substitution effects on thermal conductivity of armchair graphene nanoribbons under tensile strain: From equilibrium molecular dynamics simulations

Thermal conductivity and phonon spectra change of graphene nanoribbon as function of both side edges substitution and strain is investigated using equilibrium molecular dynamics. Under small strain, the edge’s partial substitution by graphane plays effect role to change the phonon mode of GNR. Under large tensile strain, reduction ratio of thermal conductivity is the largest in case of fluorographane hybrid and the smallest in case of graphane hybrid. Especially, under 16 % strain, the thermal conductivity of GNR is reduced until 13 % by edges substitution of graphane. The phonon spectra shift peaks towards low frequency at high frequency range (>50 THz).

Temperature‐Dependent Reversible Afterglow Between Green, Orange, and Red in Dual‐Delay Organic Doped Material

AbstractAchieving a wide‐range color‐tunable and dynamically long‐afterglow emission in a single‐doped system remains a challenge. In this study, a unique host‐guest doped material, TPA‐PTPQ/TPA, exhibits dual‐delay emission at 516 and 605 nm, both with long lifetimes of up to 108 and 145 ms, which derives from thermally activated delayed fluorescence (TADF) and room temperature phosphorescence (RTP) mechanisms, respectively. Notably, this host‐guest material demonstrates a temperature‐dependent dynamically reversible afterglow characteristic, transitioning green, orange, and red with a substantial spectra shift of ≈90 nm under different temperature conditions. This phenomenon is due to the diverse temperature effect on TADF and RTP emissions. These remarkable luminescence properties are successfully applied in security checks and anti‐counterfeiting encryption. This study provides valuable insights into the design of dynamically reversible dual‐delay‐emissive long‐afterglow luminescent materials based on a host‐guest doping system.

A new approach to assessing the consequences of radiation on the eye

The authors propose a new approach to assessing the consequences of exposure to ionizing radiation on the structures of the eye. The approach is based on the results recently obtained by the authors together with employees of the Joint Institute for Nuclear Research in Dubna, according to which radiation exposure causes oxidation of the bisretinoids contained in the structures of the eye - the retina and retinal pigment epithelium. As a result of this oxidation, the fluorescence spectrum of bisretinoids shifts to the blue region of the visible spectrum. The shift in the fluorescence spectrum can be recorded non-invasively using the method of recording fundus autofluorescence, which is currently generally accepted in ophthalmology. Since the oxidation of bisretinoids occurs during radiation exposure, it becomes possible almost immediately after irradiation to assess the degree of impact of ionizing radiation on both the structures of the eye and the body as a whole. There is no analogue to such a non-invasive assessment of the effects of radiation on the body. The proposed approach may become important for assessing the radiation safety of nuclear industry workers, astronauts, and patients undergoing proton or gamma therapy.

FBG Interrogator Using a Dispersive Waveguide Chip and a CMOS Camera.

Optical sensors using fiber Bragg gratings (FBGs) have become an alternative to traditional electronic sensors thanks to their immunity against electromagnetic interference, their applicability in harsh environments, and other advantages. However, the complexity and high cost of the FBG interrogation systems pose a challenge for the wide deployment of such sensors. Herein, we present a clean and cost-effective method for interrogating an FBG temperature sensor using a micro-chip called the waveguide spectral lens (WSL) and a standard CMOS camera. This interrogation system can project the FBG transmission spectrum onto the camera without any free-space optical components. Based on this system, an FBG temperature sensor is developed, and the results show good agreement with a commercial optical spectrum analyzer (OSA), with the respective wavelength-temperature sensitivity measured as 6.33 pm/°C for the WSL camera system and 6.32 pm/°C for the commercial OSA. Direct data processing on the WSL camera system translates this sensitivity to 0.44 μm/°C in relation to the absolute spatial shift of the FBG spectra on the camera. Furthermore, a deep neural network is developed to train the spectral dataset, achieving a temperature resolution of 0.1 °C from 60 °C to 120 °C, while direct processing on the valley/dark line detection yields a resolution of 7.84 °C. The proposed hardware and the data processing method may lead to the development of a compact, practical, and low-cost FBG interrogator.

ELSA-PSYCHE: An Improved Method for Protecting Pure Shift Spectra from Artifacts.

Numerous 1H-1H J couplings contribute to complex multiplets in 1H nuclear magnetic resonance spectroscopy, leading to an ambiguous spectral assignment, particularly for strongly coupled protons. Although the PSYCHE approach has proven to be effective in simplifying complex spectra by collapsing J couplings, the PSYCHE pure shift spectrum of strongly coupled protons always suffers from sideband artifacts and baseline oscillations, which impede spectral identification. Herein, we introduce a novel universal technique designed to separate artifacts from the desired absorption-mode pure shift signals. This new study will significantly benefit the development of molecular structure elucidations and composition analysis in the fields of chemistry, biochemistry, and metabonomics.

A Plasmonic Nanoledge Array Sensor for Selective Detection of Cardiovascular Disease Biomarkers in Human Whole Blood.

Optical sensors face challenges when detecting ultralow amounts of analytes in whole blood, including signal quenching due to optical absorption and false positives due to nonspecific binding. This study introduces gold nanoscale array features termed nanoledges (NLs), which interact with incident white light to produce a transmitted surface plasmon resonance (tSPR) signal. This extraordinary optical transmission (EOT) spectrum occurs in the near-infrared (NIR) region, thereby minimizing signal quenching caused by visible-light absorption from blood proteins and pigments. To develop a sensitive, selective, and label-free optical biosensor for detecting various levels of cardiac troponin I (cTnI) in very small volumes of whole blood samples, DNA aptamers are tethered to the NL surface, specifically binding to the cTnI biomarker. This biological binding activity alters the refractive index at the NL surface, causing a peak shift in the EOT spectrum and enabling quantification of cTnI levels. The NL array chip demonstrated high sensitivity for cTnI detection in buffer, human serum (HS), and human whole blood (HB), with detection limits of 0.079, 0.084, and 0.097 ng/mL, respectively. Control measurements using blank target mediums and those containing up to 125 ng/mL of other proteins, such as myoglobin, creatine kinase, and heparin, showed minimal interference and high specificity. The NL plasmonic array's performance in biosensing underscores its promise for clinical analysis and its potential development as a point-of-care platform for early cardiovascular disease (CVD) diagnostics.

Benzo[6,7]cyclohepta[1,2-d]pyrazolo[1,5-a]pyrimidines: Regioselective synthesis of a Novel Ring System, DFT-based NMR prediction, local reactivity indexes, and MEP analysis

Novel benzo[6,7]cyclohepta[1,2-d]pyrazolo[1,5-a]pyrimidines were prepared as a new ring system utilizing a regioselective protocol. A mixture of the appropriate 3,5-diamino-1H-pyrazoles and benzosuberone-based enones in ethanolic potassium hydroxide solution was heated at reflux for 5 h to produce the novel benzosuberone-fused pyrazolo[1,5-a]pyrimidines in 87–94 % yields. Both spectral data as well as elemental analyses were used to establish the structure of the novel products. Theoretical calculation of chemical shifts of NMR spectra is a powerful tool in analyzing experimental spectra for known substrates as well as elucidating the chemical structure for unknown ones. Using the DFT-GIAO approach under the B3LYP and mPW1PW91 functions, as well as a variety of basis sets, including 6–31G(d,p), 6–31+G(d), 6–311G(d), 6–311+G(d,p), 6–311++G-(d,p), and 6–311+G(2d,p), the chemical shifts of 1H- and 13C NMR in DMSO were calculated. The results that are most similar to the experimental observations are obtained from the computation of the chemical shift values under the 6–31G(d,p) or 6–31+G(d,p) basis sets and mPW1PW91 when using the multistranded approach. By identifying the preferred regions for electrophilic and nucleophilic attack, DFT-based FMO, global descriptors, local reactivity indexes, and MEP mapping were applied at the B3LYP function using the 6–31+G(d,p) basis set to provide additional insight into the regioselectivity in the desired reaction as well as the plausible mechanism for the formation of new products.