Probe Mode Research Articles

Effect of Mg/Ag co–doping on crystal structure, optical, and transport properties of SnO2 compound

The attempt to search for novel materials for optoelectronics material has become a highly debated and intensively investigated field of study. Within the scope of this investigation, Sn0.94Ag0.06-xMgxO2 (0 ≤ x ≤ 0.06) polycrystalline samples were produced using the traditional solid–state reaction method, and their crystalline structure, micro–structure, Raman spectroscopy, optical, and transport characteristics were investigated. Confirmation of a single rutile phase with a tetragonal crystal structure through XRD (X–ray diffraction) analysis is revealed. The morphology study by scanning electron microscopy indicated the formation of nanometric grains. All elements are evenly distributed throughout the structure, as seen by the elemental color mapping. The successful incorporation of Mg/Ag to the SnO2 lattice is evidenced by two prominent peaks in the Raman spectra of these compounds, with wavenumbers of 634 and 775 cm−1, which correspond to the A1g and B2g Raman modes, respectively. The UV–Vis spectrophotometer facilitated the acquisition of absorbance and transmittance data, which revealed that the optical band gap exhibited an expansion when the quantity of Mg/Ag co–doping increased in the SnO2 material. The transmittance value was also shown to increase from 80 % to 90 % with increased Mg co–doping concentration. The Maxwell–Weigner model has been employed to fully understand how the dielectric constant (εr), loss tangent (tan δ), complex impedance, and ac conductivity of Mg/Ag co–doped SnO2 compounds behave depending on frequency. The current–voltage (I–V) characteristics of the sample were measured using a Keithley 6517b electrometer in two–probe mode with a Tin metal pressure contact. The properties of I–V exhibited an Ohmic behavior. A study on the room temperature resistivity reveled that the materials are highly resistive in the nature.

A large-dynamic range conductivity-modulated PANI online analysis and sensing platform for ammonia gas detection using coupled optical probing mode

Due to the large-dynamic range and reversible conductivity modulation capability, polyaniline (PANI) shows promising prospects for diverse applications, such as supercapacitors, rechargeable batteries, and electrochromic materials. However, online characterization of the optical properties of the conductive polymer in the infrared band throughout the synthesis and redox state changing processes poses a challenge. Here, we propose and demonstrate an analysis and sensing platform for real-time evaluation of both thickness and the complex refractive index of PANI nanofilm, and employed for ammonia gas concentration sensing. The coupled optical probing mode of tilted fiber Bragg grating (TFBG) as a robust and portable permittivity perception tool is utilized for online perceiving the large-dynamic-range conductivity change of PANI nanofilm. By reproducing the spectral evolution of the probing cladding mode resonance, we introduce a simulation method for analyzing the optical properties of polymer nanofilms within the infrared band. For ammonia gas detection, the sensing platform exhibited continuous and reliable detection within a concentration range of 25–500 ppm, with an optimal film thickness of 156 nm. A good linear response was observed with a sensitivity of up to 5.2 × 10−3 dB/ppm, and a linearity (R2 = 0.9876) with a detection limit of 10 ppm. Our proposed low-cost and large dynamic range conductivity-modulated PANI-TFBG platform for optical properties online analysis and sensing shows potential in environmental monitoring, healthcare, and the biochemical field.

A new T-type electrosurgical knife with waterjet function used in probe mode: a safe technical variant for colorectal endoscopic submucosal dissection.

A new T-type electrosurgical knife with waterjet function used in probe mode: a safe technical variant for colorectal endoscopic submucosal dissection.

Does entanglement enhance single-molecule pulsed biphoton spectroscopy?

Abstract It depends. For a single molecule interacting with one mode of a biphoton probe, we show that the spectroscopic information has three contributions, only one of which is a genuine two-photon contribution. When all the scattered light can be measured, solely this contribution exists and can be fully extracted using unentangled measurements. Furthermore, this two-photon contribution can, in principle, be matched by an optimised but unentangled single-photon probe. When the matter system spontaneously emits into inaccessible modes, an advantage due to entanglement can not be ruled out. In practice, time-frequency entanglement does enhance spectroscopic performance of the oft-studied weakly-pumped spontaneous parametric down conversion (PDC) probes. For two-level systems and coupled dimers, more entangled PDC probes yield more spectroscopic information, even in the presence of emission into inaccessible modes. Moreover, simple, unentangled measurements can capture between 60% and 90% of the spectroscopic information. We thus establish that biphoton spectroscopy using source-engineered PDC probes and unentangled measurements can provide tangible quantum enhancement. Our work underscores the intricate role of entanglement in single-molecule spectroscopy using quantum light.

Miniaturized High‐Performance Metasurface Antenna Embedded in Cross‐Shaped Strips

A miniaturized high‐performance metasurface (MTS) antenna with cross‐shaped strips is designed, which can be applied to wireless communication systems. The resonant frequency of the main mode of the proposed MTS is reduced by embedding a 2 × 2 cross‐shaped strip array in the gaps of the 3 × 3 circular MTS array, resulting in a lower operating frequency and miniaturization. The main mode of the MTS and the probe mode are excited simultaneously by the L‐probe structure, resulting in a dual‐mode resonance for a broadband performance. The entire design mechanism of the antenna is explained analytically through characteristic mode analysis (CMA) method. Additionally, the cross‐polarization levels in H‐plane are effectively suppressed by a metal via positioned at the MTS center. Measured results show a wide impedance bandwidth of 32.6% (reflection coefficient ≤ −10 dB) with an MTS size of 0.44λ0 × 0.39λ0 (where λ0 is the free‐space wavelength of 6.6 GHz). The achieved peak gain is 7.1 dBi, with a 2 dB gain bandwidth of 36% (5.25‐7.55 GHz) and a low cross‐polarization level below ‐20 dB.

Exploring Cerebral Perfusion Transcranial Doppler Parameters in Patients Admitted to Combined Medical Surgical Intensive Care Unit

Introduction: Encephalopathy, a common complication in Intensive Care Unit (ICU) patients, is often linked to poor outcomes. Transcranial Doppler (TCD), a non-invasive tool assesses cerebral perfusion via the Pulsatility Index (PI), Resistivity Index (RI), and Time-Averaged Peak (TAP) or Mean Flow Velocity (MFV). These parameters may offer insights into cerebral perfusion and outcomes in encephalopathic patients. Aim: To describe the PI, RI of the Middle Cerebral Artery (MCA), and MFV or TAP measured by TCD in patients admitted to the ICU, comparing those with and without encephalopathy at the time of admission. Materials And Methods: This cross-sectional observational study was conducted from January 2019 to November 2020, in a combined medical-surgical ICU of a tertiary care hospital, involving 45 enrolled patients. Patients were evaluated within 24 hours of admission and subsequently every 24 hours until ICU discharge, death, or discharge against medical advice. Bilateral Middle cerebral artery TCD studies were conducted using a 1-5 MHz phased array probe or TCD mode through the transtemporal window. The PI, RI, and MFV were measured on both sides, with the higher value used for analysis, and all statistical analyses were performed using Statistics and Data 13 software. Results: In the present study, 88% (n=40) of patients had encephalopathy (GCS<15 and RAAS less than or more than 0). The mean APACHE II score was 19 (14-25), indicating severe illness with a predicted mortality of 30-40%. Patients with encephalopathy had significantly higher APACHE II scores compared to those without (19.5 (16-25) vs 10 (4-19)). Although there was a trend towards a higher Pulsatility Index in encephalopathic patients at admission (1.11±0.378 vs 1.07±0.12, p=0.81), PI, RI, and TAP values did not significantly differ in non-survivors (1.12±0.49 vs 1.11±0.33, p=0.750). Persistent encephalopathy was associated with a trend towards higher PI at admission (1.05±0.24 vs 1.16±0.46; p=0.756), and a moderate correlation was found between decreasing PI and improvement in GCS (rho=-0.489, p=0.001). Conclusions: PI, RI, and TAP at the time of admission were not found to be associated with occurrence and recovery of encephalopathy as well as mortality. The trend of change in PI moderately correlated with improvement in GCS suggesting the importance of trends rather than absolute values.

Fluorescence lifetime imaging of dynamics of mitochondrial and nucleolar microenvironment during stimuli response in living cells

Nucleolus and mitochondria play an important role in maintaining cell balance, and studying their physiological processes is helpful in understanding the biological functions. In this work, a red fluorescent pyrene rhodamine probe is used to target and label cell mitochondria and nucleolus under different conditions, and the binding mode of probe and RNA is also clarified by bio-computational simulation results. Confocal laser scanning microscopy is used to analyze the morphological changes of apoptosis in HeLa cells under the action of laser light, paclitaxel and colchicine, and the changes of micro-environmental viscosity between mitochondria and nucleolus are quantitatively analyzed by fluorescence lifetime imaging phase map. It is determined that the average fluorescence lifetime of mitochondria labeled by probes in steady-state HeLa cells is about 3.65 ns. The mitochondrial viscosity is about 66×10<sup>–3</sup> Pa·s. After laser irradiation, mitochondrial fracture and fusion occur, the fluorescence lifetime of the probe increases to 3.82 ns and the mitochondrial viscosity increases to about 131×10<sup>–3</sup> Pa·s. The mean fluorescence lifetime of the nucleolus of HeLa cells increases from 4.23 ns to 4.32 ns, indicating that the changes of the nucleolus and mitochondrial microenvironment are induced by prolonging laser irradiation. Apoptosis is induced by paclitaxel and colchicine, and the nucleolus moves out of the nucleus and into the cytoplasm. Meanwhile, the fluorescence lifetime of nucleolus and mitochondria labeled by the probe first increase and then decrease. The treatment time of paclitaxel increases from 0.5 h to 4 h, and the average lifetime of nucleolus of HeLa cells labeled by the probe increases from 4.19 ns to 4.47 ns, and finally decreases to 4.42 ns, reflecting the differences in nucleolar microenvironment of HeLa cells induced by different treatment times of paclitaxel. Comparing with the blank HeLa cell, the average lifetime of the probe increases from 4.10 ns to 4.34 ns after 1 h treatment with colchicine at low concentration (10 nM), and continuously increases to 4.47 ns after 1 h treatment with high concentration (100 nmol/L) colchicine. The microenvironments of nucleolus and mitochondria induced by apoptosis induced by colchicine at different concentrations are shown. The above three ways of inducing apoptosis, i.e. by laser light, paclitaxel and colchicine, prove that the changes of nucleolar and mitochondrial microenvironment and functional changes of HeLa cells under the condition of cell instability provide a new method of studying the dynamic process of apoptosis induced by different pathways and the diseases related to nucleolar and mitochondrial dysfunction as well.

ON THE RECONSTRUCTION OF PRESTRESS FIELDS IN A HOLLOW CYLINDER

The present research is devoted to the development of the theoretical foundations of nondestructive acoustic method for identifying inhomogeneous prestress fields in a hollow cylinder, depending on the probing loading type. A linearized model of steady oscillations of an elastic body in the presence of an inhomogeneous prestress field of arbitrary nature is considered in the standard and weak formulations. On the basis of this model, we formulate a problem for a cantilever-clamped prestressed hollow cylinder that performs steady axisymmetric vibrations under three types of probing loading. A corresponding weak formulation of the problem in the cylindrical coordinate system is presented, in which six independent components of the prestress tensor are taken into account. At that, a case of prestress fields obtained by applying some initial mechanical external static load is considered. In the presence and absence of prestresses of various types, amplitude-frequency dependences are analyzed, and resonant and natural frequencies are found in a wide frequency range. Numerical calculations were carried out using the FEM on a non-uniform grid; mesh refinement is carried out in the vicinity of the boundary points, where the type of boundary conditions changes. Based on the numerical solution of an auxiliary set of direct problems, seven types of prestress fields are constructed, differing in the types of initial loading, most often encountered in practice. To assess the possibility of implementing the procedure for reconstructing prestresses of each of the considered types, a sensitivity analysis was additionally performed, which showed that for some prestress types there are frequencies and types of probing loading for which the presence of prestress is practically not manifested. The sensitivity analysis performed made it possible to implement the optimal method of probing loading when solving the inverse coefficient problem. The statement of the new inverse problem on the restoration of arbitrary inhomogeneous prestress fields in the considered finite hollow cylinder is formulated. When restoring the prestress of a given structure, the inverse problem is reduced to finding a set of parameters from an ill-conditioned algebraic system, which was studied with the help of the A.N. Tikhonov regularization method. Additional data for solving the inverse problem was obtained on the basis of probing both via a single load and via combined probing modes. It has been found that it is most effective to use a combined loading mode and use a sufficiently wide frequency range when selecting sounding frequencies. The results of computational experiments on the reconstruction of six components of the prestress tensor are presented and analyzed, and recommendations are proposed for choosing the optimal modes of acoustic sounding.

Pulsatile Femoral Vein Doppler Pattern is a Parameter of Venous Congestion in ICU Patients

ObjectivesThe aim of this study was to evaluate whether the presence of a pulsatile femoral vein pattern is and indicator of venous congestion in ICU; DesignRetrospective observational study; SettingThree medico-surgical university-affiliated ICUs; ParticipantsAdult patients who had ultrasound evaluation at several time points during ICU stay: at baseline (within 24h of admission to ICU), and/or daily during ICU stay, and/or within 24h before ICU discharge; InterventionsAt each time point, the hemodynamic, respiratory and cardiac ultrasound parameters were recorded. The common femoral vein was studied with pulsed-wave Doppler at the level of the femoral trigonum, with high frequency (5–13 MHz) linear array vascular probe and venous vascular mode, in supine patients. Measurements and Main resultsOne hundred-and-eight patients who underwent 400 ultrasound evaluations (3.7 ± 1 ultrasound evaluations per patient) during their ICU stay were included. 79/108 patients (73%) had a pulsatile femoral vein pattern at least at one timepoint. The multivariable mixed effects logistic regression model demonstrated an association between pulsatile femoral vein pattern, BMI (OR: 0.91(CI95%: 0.85-0.96), p=0.002), IVC mean diameter (OR:2.35 (CI95%: 1.18-4.66), p=0.014), portal vein pulsatility (OR: 2.3 (CI95%:1.2-4.4), p=0.012), and congestive renal vein flow pattern (OR: 4.02 (CI95%: 2.01-8.03), p<0.001). The results were confirmed by principal component analysis. ConclusionIn ICU, a pulsatile femoral vein pattern is associated with parameters of venous congestion, independently of patient's volume status, and ventilatory treatment. These results suggest the femoral vein Doppler pulsatility as a parameter of congestion in ICU patients.

Triangle Tip-Jet Knife used as "probe mode" can reduce the risk of mucosal damage during incision and tunneling phase of peroral endoscopic myotomy (POEM) procedures.

Peroral endoscopic myotomy (POEM) is a minimally invasive endoscopic technique for the treatment of achalasia and its use has been widely spread in recent years. The Triangle Tip-Jet (TTJ) (Olympus Triangle TipKnife-J, KD645L) has become very popular in this field and currently one of the most used knives for POEM procedures. It has the capability of knife dissection along with submucosal injection and its triangle tip shape is especially useful for pulling tissue during the myotomy phase. However, its length may be too long in situations such as tight esophagogastric junction (EGJ), narrow submucosa due to fibrosis, trimming after mucosal incision and/or less experienced endoscopists3 in which preserving the integrity of the mucosa is vitally important. Distal attachment conical caps like ST Hood (DH28GR,29CR; Fujifilm, Tokyo, Japan) are commonly used for POEM, resting the distal end of the TTJ on the cap, with only the triangular tip protruding. By using straight caps, you can get a wider view and greater maneuverability, however is more difficult to calculate the distance between the triangle tip and the distal attachment end due to its straight shape. The T-shape of the distal TTJ tip was designed for its use in an open position. In this way, while using straight caps and/or less experiences endoscopists during challenging procedures (tight EGJ, submucosal fibrosis) can make them feel unsafe during incision and/or tunneling phase. Herein, we suggest the use of the TTJ knife in "probe mode"4 to reduce the distal knife length from 4.5 mm to 0.3 mm, thus allowing a greater control of the knife tip. In addition, the TTJ probe mode can be safely used with both contact and non-contact currents, which are becoming increasingly popular in recent years.

1, 10-phenanthroline derivative as colorimetric and ratiometric fluorescence probe for Zn2+ and Cd2+

A colorimetric and ratiometric fluorescent probe 2-phenyl-1H-imidazo[4,5-f][1,10]phenanthroline (probe 1), was designed and synthesized for sensitive and selective detection of Zn2+ and Cd2+ ions in methanol, test paper and actual water samples. When probe 1 was excited at 350 nm in methanol solution, in the presence of alkali metal ions, alkali-earth metal ions and a variety of transition metal ions, it showed sensitive fluorescence selectivity to Zn2+ and Cd2+ ions. With the addition of Zn2+, the color of the solution changed from purple to cyan with the naked eye, and with the addition of Cd2+, the color of the solution changed from purple to blue. The fluorescence intensity of probe 1 showed a good linear relationship with Zn2+ and Cd2+ concentrations, and the detection limits were 0.04 μM and 0.11 μM, respectively. The binding mode of probe 1 and Cd2+ was discussed according to the 1-Cd single X-ray crystal structure. In addition, the results of strip test and real water sample test showed that probe 1 has potential application in environmental metal ion recognition and detection.

Phenanthroline-based ligand scaffold as an efficient colorimetric and ratiometric fluorescence probe for Zn2+ and Cd2+ ion detection

A colorimetric and ratiometric fluorescent probe 2-(naphthalen-2-yl)-2,11b-dihydro-1H-imidazo[4,5-f][1,10]phenanthroline (probe 1), was designed and synthesized for sensitive and selective detection of Zn2+ and Cd2+ in methanol, test paper and actual water samples. When probe 1 was excited at 350 nm in methanol solution, in the presence of alkali metal ions, alkali-earth metal ions and a variety of transition metal ions, it showed sensitive fluorescence selectivity to Zn2+ and Cd2+. With the addition of Zn2+, the color of the solution changed from purple to green with the naked eye, and with the addition of Cd2+, the color of the solution changed from purple to cyan. The fluorescence intensity of probe 1 showed a good linear relationship with Zn2+ and Cd2+ concentrations, and the detection limits were 0.09 μM and 0.06 μM, respectively. The binding mode of probe 1 and Zn2+ was discussed according to the 1-Zn single X-ray crystal structure. In addition, the results of strip test and real water sample test showed that probe 1 has potential application in environmental metal ion recognition and detection.

Extracting bath information from open-quantum-system dynamics with the hierarchical equations-of-motion method

We present a simple and effective approach for extracting the bath information in open-quantum-system dynamics under the framework of the numerically exact hierarchical equations-of-motion method, for which it is usually not straightforward to adjust the boundary between the system and bath. The key component of our approach is an additional bath mode that weakly interacts with the system through the same coupling channel as the mode of interest, which we call the probe mode. By combining the probe mode with the system and calculating its expectation value, we can deduce the corresponding expectation value of the mode of interest via simple relations. The effectiveness of our approach is demonstrated by exact decomposition of dissipation by a continuous spectral density.

A colorimetric and ratiometric fluorescence probe for Zn2+ and Cd2+ with 1,10-phenanthroline derivative

A colorimetric and ratiometric fluorescent probe 2-([1, 1′-biphenyl]-4-yl)-2, 3b,11a,11b-tetrahydro-1H-imidazo[4,5-f][1,10]phenanthroline (probe 1), was designed and synthesized for sensitive and selective detection of Zn2+ and Cd2+ in methanol, test paper and actual water samples. When probe 1 was excited at 350 nm in methanol solution, in the presence of alkali metal ions, alkali-earth metal ions and a variety of transition metal ions, it showed sensitive fluorescence selectivity to Zn2+ and Cd2+. With the addition of Zn2+, the color of the solution changed from purple to green with the naked eye, and with the addition of Cd2+, the color of the solution changed from purple to cyan. The fluorescence intensity of probe 1 showed a good linear relationship with Zn2+ and Cd2+ concentrations, and the detection limits of both Zn2+ and Cd2+ were 0.11 μM. The binding mode of probe 1 and Zn2+ was discussed according to the 1-Zn single X-ray crystal structure. In addition, the results of strip test and real water sample test showed that probe 1 has potential application prospect in environmental ion recognition.

Cucurbit[7]uril Macrocyclic Sensors for Optical Fingerprinting: Predicting Protein Structural Changes to Identifying Disease-Specific Amyloid Assemblies.

In a three-dimensional (3D) representation, each protein molecule displays a specific pattern of chemical and topological features, which are altered during its misfolding and aggregation pathway. Generating a recognizable fingerprint from such features could provide an enticing approach not only to identify these biomolecules but also to gain clues regarding their folding state and the occurrence of pathologically lethal misfolded aggregates. We report here a universal strategy to generate a fluorescent fingerprint from biomolecules by employing the pan-selective molecular recognition feature of a cucurbit[7]uril (CB[7]) macrocyclic receptor. We implemented a direct sensing strategy by covalently tethering CB[7] with a library of fluorescent reporters. When CB[7] recognizes the chemical and geometrical features of a biomolecule, it brings the tethered fluorophore into the vicinity, concomitantly reporting the nature of its binding microenvironment through a change in their optical signature. The photophysical properties of the fluorophores allow a multitude of probing modes, while their structural features provide additional binding diversity, generating a distinct fluorescence fingerprint from the biomolecule. We first used this strategy to rapidly discriminate a diverse range of protein analytes. The macrocyclic sensor was then applied to probe conformational changes in the protein structure and identify the formation of oligomeric and fibrillar species from misfolded proteins. Notably, the sensor system allowed us to differentiate between different self-assembled forms of the disease-specific amyloid-β (Aβ) aggregates and segregated them from other generic amyloid structures with a 100% identification accuracy. Ultimately, this sensor system predicted clinically relevant changes by fingerprinting serum samples from a cohort of pregnant women.

Ionic Dynamics and Vibrational Spectral Diffusion of a Protic Alkylammonium Ionic Salt through Intrinsic Cationic N-H Vibrational Probe from FPMD Simulations.

We employed density functional theory (DFT)-based molecular dynamics simulations to explore the structure, dynamics, and spectral properties of the protic ionic entity trimethylammonium chloride (TMACl). Structural investigations include calculating the site-site radial distribution functions (RDFs), the distribution of constituent cations and anions in three-dimensional space, and combined distribution functions of the hydrogen-bonded pair RDF versus angle, revealing the structural characteristics of the ionic solvation and the intermolecular interactions within ions. Further, we determined the instantaneous vibrational stretching frequencies of the intrinsic N-H stretch probe modes by applying the time-series wavelet method. The associated ionic dynamics within the protic ionic compound were investigated by calculating the time-evolution of the fluctuating frequencies and the frequency-time correlation functions (FFCFs). The time scale related to the local structural relaxation process and the average hydrogen bond lifetime, ion cage dynamics, and mean squared displacement were investigated. The faster decay component of the FFCFs, depicting the intermolecular motion of intact hydrogen bonds in TMACl, is 0.07 ps for the Perdew-Burke-Ernzerhof (PBE)-based simulation and 0.06 ps for the PBE-D2 representation. The slower time scale of the longer picosecond decay time component of PBE and PBE-D2 representations are 3.13 and 2.87 ps, respectively. These picosecond time scales represent more significant fluctuations of the hydrogen-bonding partners in the ionic entity and hydrogen-bond jump events accompanied by large angular jumps. The longest picosecond time scales represent structural relaxation, including large angular jumps and ion-pair dynamics. Also, ion cage lifetimes correlate with the slowest time scale of the associated dynamics of vibrational spectral diffusion despite the type of DFT functional. This study benchmarks DFT treatments of the exchange-correlation functional with and without the van der Waals (vdW) dispersion correction scheme. The inclusion of vdW interactions to the PBE functional represents a less structured state of the ionic entity and faster dynamics of the molecular motions relative to the one predicted by the PBE system. All the results illustrate the necessity of accurately describing the Coulomb interactions, vdW dispersive interactive forces, and localized hydrogen bonds required to sustain the energetic balance in this ionic salt.

Microheterogeneity-Induced Vibrational Spectral Dynamics of Aqueous 1-Alkyl-3-methylimidazolium Tetrafluoroborate Ionic Liquids of Different Cationic Chain Lengths.

We have monitored the impacts of an increment in the alkyl chain length of the imidazolium-based tetrafluoroborate ionic liquids on the local deuteroxyl probe modes of interest. For this study, we have taken 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIm][BF4], 1-butyl-3-methylimidazolium tetrafluoroborate [BMIm][BF4], 1-octyl-3-methylimidazolium tetrafluoroborate [OMIm][BF4], and 1-decyl-3-methylimidazolium tetrafluoroborate [DMIm][BF4] ionic liquid solutions with 5% HOD in H2O as the vibrational reporter of the associated ultrafast system dynamics. Classical molecular dynamics (MD) simulations were employed to determine molecular structure and dynamic properties, while the spectral profiles were derived by applying the wavelet analysis of classical trajectories. Spatial distribution functions reveal the heterogeneity within the molecular structures of the ionic liquids (ILs) with varying alkyl chain lengths. The intense position of the spectral peak, the frequency corresponding to the shoulder peak, and the spectral linewidth of the O-D stretch distribution are not influenced by the increment in the cationic chain length. In addition, the ionic liquid (IL) [BMIm][BF4] exhibits a notable trend; the dynamic timescales are longer than the other studied systems. Therefore, we have performed the Voronoi decomposition analysis of the ionic and the polar-apolar domains, symmetrically increasing the length of alkyl chains on the IL cations. Domain analysis reveals structural microheterogeneity; the anions form discrete domains, and the ionic liquid constituting cations form continuous domains irrespective of the alkyl chain length on the imidazolium cations. Therefore, this computational ultrafast spectroscopy study aids in forming a molecular-level picture of the ionic liquid cations and anions in the liquid phase, providing a detailed interpretation of the spectral properties of the probe stretching vibrations.

Vibrational spectral dynamics and ion-probe interactions of the hydrogen-bonded liquids in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide

We investigate ion-probe interactions within the molecular liquid, examine dynamics, and interpret the vibrational spectral dynamics of the mixtures of ionic liquid, 1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [EMIm][NTf2] with the probes of varying alkyl chain length – HOD, methanol-d4, ethanol-d6. Structural analysis depicts pronounced interactions of the oxygen atom of HOD with the corresponding anionic oxygen site rather than the hydrogen atom located at the two-position of the imidazolium ring. Our computed frequency distribution for each of the probes in IL exhibits similarity with the experimental linear FT-IR spectrum. We further performed the orientational anisotropy calculations; the ion reorientation plays a significant role in determining the transport properties in ILs. The results of rotational anisotropy of the O-D bond vector reflect the hydrogen bond length-scale fluctuations and collective reorientation associated with the complete structural reorganization of the probe modes. Our findings in this study agree well with the earlier experimental and simulation studies.

Теоретические аспекты метода фазового зонда

The authors discuss theoretical matters inherent in modern algorithms for processing satellite measurements’ data. Using the simplest radio navigation system MPS (abbreviation for Mandelstam, Papaleksi, Schegolev), developed in the USSR in 1936 as an example, it was shown that the main drawback of existing algorithms is that they did not use the mathematical notation of simultaneous registration of phase cycles, and all researchers, without exception, note the importance of these acts. It is proved that the operation of resolving ambiguity is not theoretically justified. It is recommended to record the duration of the measurement session, and it is proved that this can serve as an additional source of information. Based on the studies, a simple, unified, and rigorous algorithm for calculating the coordinates of the points to be determined from the results of registering phase cycles at using the radio navigation system in the phase probe mode is recorded.

A ratiometric fluorescent, colorimetric, and paper sensor for sequential detection of Cu2+ and glutathione in food: AIEE and reversible piezofluorochromic activity

A new Schiff base 2 was rationally synthesized that exhibited aggregation induced emission enhancement (AIEE) and unique reversible piezofluorochromic properties. Probe 2 displayed a distinguished ratiometric fluorescent and colorimetric recognition of Cu2+ and further acted as a probe for the selective detection of glutathione (GSH) based on its 2–Cu2+ complex. Firstly, probe 2 showed a highly selective fluorescence quenching response towards Cu2+ over its competing ions that was attributed to the intermolecular charge transfer (ICT) to paramagnetic Cu2+. Based on ratiometric fluorescence titration, the limit of detection (LOD) of probe 2 for Cu2+ was calculated as 2.13 nM. The complexation mode of probe 2 for Cu2+ was confirmed through 1H NMR titration, Job plot, computational, and DLS studies. Subsequently, the addition of GSH to probe 2–Cu2+ complex immediately enhanced its fluorescence, and the emission of probe 2 was recovered which was ascribed to the displacement of Cu2+ by GSH and release of probe 2. The developed strategy for the identification of GSH was confirmed through 1H NMR titration experiments. Advantageously, probe 2 and probe 2–Cu2+ complex coated paper sensors were successfully developed for the nanoscale sensing of Cu2+ and GSH in food samples. The detection of Cu2+ and GSH in food and actual water samples was adequately accomplished through a very effective dip-coating method. Finally, a sequential detection strategy was used to design logic circuits.