Optimized Geometry Structure Research Articles

Investigation of geometry-dependent sensing characteristics of microfluidic for single-cell 3D localization.

Flow cytometry-based measurement techniques have been widely used for single-cell characterizations, such as impedance, size, and dielectric properties. However, in the measurement process, the reliability of the output measurement signal directly affects the ability of the microsystem to judge the characteristics of single cells. Here, we designed a multiple nonparallel electrode structure for single-cell 3D localization. The performance of the structures was studied by analyzing the changes in electric field strength and the output differential current. The effects of microchannel height, sensing electrode distance, electrode inclination angle, and electrode width on output signals are investigated by analyzing the current change and electric field strength of single cells passing from the center of the microchannel. The numerical simulation results indicate that, when the microchannel height is 20 µm, the distance of the sensing electrodes is 100 µm, the inclination angle is 30°, the electrode width is 20 µm, and the optimal signal quality can be obtained. Reducing the height of the flow channel and shortening the sensing electrode spacing can significantly improve the signal amplitude. When the channel height is 20 µm, the signal intensity increases by 80% than that of 30 µm. The signal intensity of induced current with the sensing electrode spacing of 100 µm is 42% higher than that with the spacing of 120 µm. We analyzed the presence of multiple independent cells and adherent cells in the detection area and demonstrated through simulation that the signal changes caused by multi-cells can be superimposed by multiple single-cell signals. The induced current signal intensity of the same volume of cells with an ellipticity of 1 is 49% lower than that of cells with an ellipticity of 4. Based on the numerical investigation, we expect that the optimal geometry structure design will aid in the development of better performance signal cell impedance cytometry microsystems.

Stability of bonds, kinetic stability, energy parameters, spectral characterization, GC–MS and molecular descriptors studies on coumarine, 3-[2-(1-methyl-2-imidazolylthio)-1-oxoethyl

In the current study, the CMIO molecules synthesised from carbinol crude of the Hybanthus Enneaspermus plant was identified in GC–MS results. The vibrational frequencies assigned through theoretical and experimental results are well correlated. The electronic transitions n→π*, n→σ* performed by the TD-DFT approach. The optimized geometry structure found stability for single bonds (S1C15), double bonds (C19C21) and was compared with XRD values. Donor-acceptor interaction and highest bond strength investigated by the NBO population. Energy gap, electrophilicity, nucleophilicity index, Mulliken population analysis, MEP plot analysis of reactive sites, and all the theoretical parameters interpreted by the B3LYP/6–311G(d,p) technique. Moreover, the various degree-based topological indices used to analyse the CMIO molecules and the docking studies show excellent binding energy between ligand and 2RFN protein against kidney cancer activity.

Design and analysis of high-sensitivity multilayered structure surface acoustic wave sensor for dichloromethane gas detection

Micro- and nano-sensors are key devices used in various fields from medical to environmental science. With the progress of micro- and nano-fabrication technology and the use of newly designed materials, sensor design has been significantly improved, leading to the development of high-performance gas sensors. A novel multilayer structure gas sensor based on surface acoustic wave (SAW) is proposed for the detection of volatile harmful gas dichloromethane. The gas sensing characteristics of single-layer and multilayer SAW sensors were studied by using finite element method. The influence of geometric parameters on the sensor performance was analyzed and the optimal structure was determined. The propagation characteristics of SAW were obtained by transient simulation of the whole structure. The sensitivity of the sensor is evaluated by placing the sensor in different concentrations of dichloromethane gas. The results show that the sensitivity of the PIB/AlN/Diamond/Si SAW gas sensor is as high as 66.9 ppm/Hz under the optimal geometry structure, which is nearly 30 times higher than that of other single-layer and multilayer SAW sensors. This work provides a good solution for the design of high-sensitivity SAW sensors.

Corrosion characterization of steel wires based on persistent homology theory for magnetostrictive guided wave testing signal

Corrosion of steel wires in cables is a frequent occurrence and is a major factor affecting the durability and safety of cables. Magnetostrictive guided waves have been employed to detect steel wire corrosion. However, due to the complexity of the geometry of the corrosion area, it is difficult to interpret the magnetostrictive guided wave testing signals. Hence, extracting features from testing signals to characterize the corrosion condition is a great challenge. This study proposes a topological feature for corrosion characterization of steel wire, which is extracted from the two-dimensional point cloud with optimal geometry structure of the testing signal based on persistent homology theory. Corrosion experiments were carried out on 30 galvanized steel wires. The experimental results indicate that the topological feature increases roughly linearly with the corrosion depth. Furthermore, compared to other features obtained from the time domain, frequency domain, and joint time–frequency domain, this topological feature can reflect the progression of corrosion more accurately.

Structural, optical and DFT studies of disodium phthalocyanine thin films for optoelectronic devices applications

Theoretical and experimental investigations have been carried out on the structural and optical properties of disodium phthalocyanine (Na2Pc) thin films prepared using the thermal evaporation method. The optimized geometry structure, vibrational bands and HOMO-LUMO gap were predicted by density functional theory (DFT) computations. FTIR and XRD techniques were utilized to analyze the structural characteristics of Na2Pc thin films. XRD exhibited that the Na2Pc powder has α-polycrystalline nature with a triclinic structure, whereas the Na2Pc thin films have an amorphous structure. The optical properties of different thicknesses films were studied in the wavelength range of 200–2500 nm using the UV–Vis-NIR spectrophotometer. The absorption coefficient of the Na2Pc molecules showed four absorption bands in the UV–Vis region. The types of optical transitions were determined by applying the energy band model as an indirect allowed transition. The onset gap, optical gap and Urbach energy were estimated to be 1.31, 2.25 and 0.41 eV, respectively. The results of absorption coefficient and energy gap showed that the Na2Pc thin films can be utilized in optoelectronic device applications. The absorption index, k, and refractive index, n, were determined and found to be independent of the film thickness. The dispersion parameters have been evaluated according to a single oscillator model in the non-absorbing region of the spectrum.

Adsorption of toxic and harmful gas CO on TM (Ni, Pd, Pt) doped MoTe2 monolayer: A DFT study

The effect of transition metal atom (Ni, Pd, Pt) dopants on the adsorption behavior of MoTe2 monolayer adsorbed CO was studied computationally based on a first principles study. The optimized geometry structure, adsorption parameters, band structure (BS) and density of states (DOS) of CO gas adsorption on MoTe2 and TM-MoTe2 surfaces were calculated and compared with the aim of clarifying the adsorption mechanism. The analysis results findings show that the adsorption effect of TM-MoTe2 monolayer for CO gas is significantly stronger than that of intrinsic MoTe2. The amount of charge transfer increases significantly, and the adsorption processes are all chemical adsorptions. The results of this study expound the gas adsorption mechanism of MoTe2 material, and stablish a reliable theoretical foundation for the detection of toxic and harmful gases by MoTe2 sensor.

Conceptual design and performance optimization of a nighttime electrochemical system for electric power generation via radiative cooling

The conceptual design of a nighttime electrochemical system (NECS) based on radiative cooling for generating electrical power from dark night sky is proposed. Such a low temperature and passive device is capable of generating electricity during nighttime without active input of heat. A comprehensively theoretical model is developed to study its performance characteristics and parametric optimum design. The model predicts that an output power density larger than 2 W/m2 at 303.15 K is achievable, which is potentially more advantageous than that of previously proposed nighttime thermoelectric generator. The calculated results show that the heat convection conditions, optimized geometry structure, and the choice of selective radiative cooler play a critical role in improving the device performance. This work reveals the new concept of the NECS and provides important insights for the optimal designs of the NECS, thus paving a new way towards high-performance nighttime electric power generation.

A comprehensive study of structural, vibrational, electronic properties of celecoxib compound by density functional theory

This paper describes the spectroscopic (FT-IR and UV–Visible), electronic, structural, vibrational properties of celecoxib compound using density functional theory. The optimized geometry structure of the titled molecule is explained by the method of B3LYP with 6–31 + G (d, p) basis set. We found that the simulated optimized geometry of the titled molecule is simulated to the experimental ones. The infrared spectrum of celecoxib compound is represented in the present work. The computational information about the organic molecule can be explained by the charge transfer properties, which is a computational tool for the precise quantum chemical calculations of space charge density distribution and HOMO-LUMO states. The transition states of celecoxib compound have explained by the time-dependent density functional theory (TD-DFT) which is observed by the UV–visible spectrum. Docking research [1] is a modeling method, with the help of docking method we can find out new drug and chemical behavior of the drug which is useful in the application purpose of the drug, the interaction between protein and legends provides the information of the binding energy and physical parameter like partition function, free energy, internal energy, entropy.

Biophysical binding profile with ct-DNA and cytotoxic studies of a modulated nanoconjugate of umbelliferone cobalt oxide loaded on graphene oxide (GO) as drug carrier

In an attempt to identify suitable nano-carriers for drug delivery, natural drug umbelliferone was chosen to synthesize new modulated nanoconjugate of umbelliferone cobalt oxide with cobalt (II) nitrate in one pot assembly in the presence of tannic acid. The synthesized nanoconjugate drug (NCD) was then loaded on graphene oxide (GO) as drug carrier by simple ultrasonication method and thoroughly characterized by various spectroscopic techniques (FT-IR, SEM, TEM, XRD, EPR and thermogravimetric analysis) which revealed the successful loading of the nanoconjugate drug on GO. The UV-visible, fluorescence and electrochemical studies suggested that strong π-π stacking interactions exist between nanoconjugate drug and GO. The binding studies of NCD-GO with ct-DNA were performed by various optical and biophysical methods viz., UV-visible, fluorescence, circular dichroism (CD) and cyclic voltammetry (CV) which indicated electrostatic mode of binding towards the ct-DNA. Furthermore, condensate of nanoconjugate drug-loaded GO (NCD-GO) with ct-DNA was prepared and analyzed by scanning electron microscopy (SEM) which revealed that the interaction of NCD-GO with ct-DNA had occurred. Cleavage activity of NCD-GO with pBR322 was evaluated by gel electrophoresis and it was found that NCD-GO cleave DNA through hydrolytic pathway involving hydroxyl radical (OH). The cytotoxicity of NCD-GO was evaluated against human liver carcinoma (Huh-7), prostate cancer (Du-145) cell lines along with normal cell line (PNT 2). The results obtained showed selective cytotoxic activity of NCD-GO against Du-145 cell lines. The intracellular uptake was visualized by confocal microscopy which revealed the significant cellular uptake and internalization of nanoparticles by cells. Moreover, the adsorption of cobalt oxide umbelliferone on GO was studied by density functional theory. The process of adsorption was found exothermic in nature and the optimized geometry structure is quite stable. Communicated by Ramaswamy H. Sarma

Sandwich Au/SMSiO2/Ag hybrid substrate: synthesis, characterization, and surface-enhanced Raman scattering performance

Surface-enhanced Raman scattering (SERS) has been considered a high sensitivity, specificity, and ultra-fast analytical technique in molecular fingerprint recognition. Herein, a kind of sandwich Au/“star-like” mesoporous SiO2/Ag (Au/MSiO2/Ag) hybrid nanostructure was developed by implementing the electrostatic adsorption and magnetron sputtering technology for SERS application. In the experiment, the decoration density of the MSiO2/Ag nanostructure was conveniently adjusted through tuning the washing times of the silicon wafer in ethanol. The prepared substrate with the optimal geometry structure exhibited an enhancement factor (EF) of 9.2 × 105, a limit of detection (LOD) of 5 × 10−5 M, and a low relative standard deviation value of 5.02%. In the end, the obtained hybrid SERS substrate was used to detect nitrofurazone and an excellent LOD of 1 ppm was achieved. Overall, our novel sandwich Au/MSiO2/Ag hybrid SERS substrate provides a rapid and accurate way of monitoring ultra-low trace antibiotics, which can significantly promote food safety.

A density functional theory study of metalloporphyrin derivatives act as fluorescent sensor for rapid evaluation of trimethylamine

A fluorescent sensor based on metalloporphyrin was developed for trimethylamine (TMA) evaluation. Density functional theory (DFT) has been performed to investigate the design mechanism of fluorescent sensor. Fourteen metalloporphyrin (MP) models were selected to find the influence of metal atoms and substituent groups on the binding performance of fluorescent sensor. The optimized geometry structures, relative energies, mulliken charges, spin densities, and four frontier molecular orbitals together with binding energies of these fluorescent sensors were investigated. AgP sensor has the lowest relative energies before and after exposure to TMA, which make AgP sensor better than the others to go through more than one pathway. Binding energy results revealed that the metalloporphyrin sensors with different metal atoms and substituent groups cause remarkable changes in TMA binding performances. Thus, theoretical investigations can be used to extend the fluorescent sensor in to TMA related analytes in different detection requirements, and perhaps other molecule.

Double Stopband Bilayer Photonic Crystal Based Upconversion Fluorescence PSA Sensor

Precise detection on tumor markers is significant for the early diagnosis on cancer. Upconversion fluorescence probes are ideal for tumor marker sensing, but still subject to bottleneck problems of low emission efficiency/strength. In this work, a novel bilayer of poly(methyl methacrylate) opal photonic crystal (PMMA OPC) with double photonic stop bands was fabricated to match the excitation field and emission field of the upconversion nanoparticles (UCNPs) at the same time, and greatly enhance their upconversion fluorescence intensity. Herein, NaYF4:Yb3+,Er3+ UCNPs and NaYF4:Yb3+,Er3+@NaYF4:Yb3+,Nd3+ UCNPs with a core-shell structure were employed as a core, which could be excited by 980 nm and 808 nm light, respectively. With the optimized geometry structure, the upconversion emission intensity was enhanced over 150 folds under the excitation of both 808 nm and 980 nm laser. Through the NaYF4/OPC biochip and florescence resonant energy transfer (FRET) sensing strategy, the lowest detection limit of 0.01 ng/mL with good linear relationship was obtained ranging from 0.1 ng/mL to 10 ng/mL. The power density of the pumping light was as low as 1.7 W/cm2. This enhanced upconversion tumor marker biochip sensor provides a promising and powerful tool for facile early diagnosis on cancer markers.

Mechanistic Insight of Metalloporphyrin-based Fluorescence Sensor Reacting with Volatile Organic Compounds

The theoretical design of a metalloporphyrin-based fluorescence sensor was developed for the discrimination of volatile organic compounds (VOCs). Molecular models of cobalt tetraphenylporphine (CoTPP) with small VOCs were investigated by the density functional theory (DFT) method at the Becke, 3-parameter, Lee–Yang–Parr (B3LYP) and LAN2DZ level. The relative energies of CoTPP and its complexes were calculated at three spin states (low, intermediate, and high) to obtain their optimized geometry structures. Singlets were found to be the most stable states for CoTPP and its complexes, except for CoTPP-oxygen and CoTPP-propanol at triplets. The binding performance was represented by the binding energy (BE), which showed the following order based on the most stable states: propane (L3) < oxygen (O2) < propanol (L2) < hydrogen sulfide (H2S) < propionaldehyde (L6) < nitrogen (N2) < butanone (L5) < ethyl acetate (L4) < trimethylamine (L1). We suggest that the CoTPP-based fluorescence sensor is sensitive to trimethylamine and ethyl acetate, and avoids the interference from propane and oxygen.

A Theoretical Study of Metalloporphyrin-Based Fluorescent Array Sensor using Density Functional Theory.

The influences of metal atoms on optimized geometry structures, relative energies, frontline molecular orbitals, and binding energies of metalloporphyrin-based fluorescent array sensor were systematically investigated by density functional theory (DFT) at B3LYP/LAN2DZ level. DFT calculated results reveal that the selected metal atoms in the center of the metalloporphyrin plane provide difference performances of metalloporphyrin-based fluorescent array sensor for the rapid determination of trimethylamine. The calculated binding energies have displayed in the following order at the most stable states: zinc porphyrin (ZnP) < copper porphyrin (CuP) < silver porphyrin (AgP) < iron porphyrin (FeP) < tin porphyrin (SnP) < cobalt porphyrin (CoP) < ruthenium porphyrin (RuP) < manganese porphyrin (MnP). Therefore, this theoretical study provides a design mechanism for how to choose a proper metal atom for low or high concentration trimethylamine. This research also suggests that theoretical results may be useful for the rapid detection of food containing trimethylamine.

Evidence for stepwise excited state double proton transfer process in quinolone–pyrazole triggered by methanol solvent

Basing on the density functional theory and time-dependent density functional theory, we present a systematic theoretical investigation on the excited state double proton transfer process (ESDPT) of quinolone–pyrazole (QP) in methanol (MeOH). The theoretical results provide convincing evidence that ESDPT process takes place in QP-MeOH hydrogen bond (HB) complex. The analysis of the optimized geometry structures and non-covalent interactions adequately demonstrates that the strengthened intermolecular HBs make remarkable effect on the ESDPT process. Meanwhile, the frontier molecular orbitals have been delineated to understand the driving force of the ESDPT process. The changes of characteristic peaks in the infrared spectra further prove the occurrence of the ESDPT process. Combining with the analysis of constructed potential energy curves, the ESDPT mechanism for QP-MeOH complex is clearly clarified. Our studies not only shed light on the nature of ESDPT process of QP-MeOH, but also be helpful to design novel promising photoelectric materials.

Understanding the impact of polymorphism on the electronic structures and charge transport properties of contorted hexabenzocoronene

Organic semiconductors with polymorphism characteristics have been attracted increasing attention for their great importance on disclosing the structure-property relationship of organic solids. The impact of polymorphism on the electronic structures and charge transport properties of contorted hexabenzocoronene (c-HBC) is explored based on density functional theory (DFT) method combined with Marcus electron transfer theory. The geometry structures, reorganization energies, frontier molecular orbitals, ionization energies, electronic affinities, crystal packing motif, transfer integrals as well as charge carrier mobilities of three polymorphs are investigated to establish the relationship between the structure and property. The results show that the polymorphism has little influence on the optimized geometry structures, reorganization energies, and the distribution of the frontier molecular orbitals. The reorganization energies of hole and electron for the three polymorphs are small, which are 0.11 and 0.15 eV, respectively. However, the crystal packing arrangements and the transfer integrals of the three polymorphs are significantly different, leading to different charge carrier mobility. All the three polymorphs show high hole mobilities, indicating that they could be used as p-type semiconductors. Specially, for polymorph II, the calculated hole mobility is as high as 0.90 cm2V−1s−1. Meanwhile, the electron mobilities of polymorphs II and III are in the same order of magnitude with the hole mobilities, which are 0.47 and 0.17 cm2V−1s−1, respectively. Due to the high hole and electron mobilities of polymorph II, it may be used as a bipolar transport semiconductor.

Theoretical design on a new double functional device of 2,2′‐bipyridine‐embedded N‐(9‐pyrenyl methyl)aza‐15‐crown‐5

AbstractTheoretical design on a new molecular switch and fluorescent chemosensor double functional device of aza‐crown ether (2,2′‐dipyridine‐embedded N‐(9‐anthraceneyl(pyrenyl)methyl)aza‐15‐crown‐5) was explored. The interactions between ligands and a series of alkaline earth metal cations (Mg2+, Ca2+, Sr2+, and Ba2+) were investigated. The fully optimized geometry structures of the free ligands (L1, L2) and their metal cation complexes (L1/M2+, L2/M2+) were calculated with the B3LYP/6‐31G(d) method. The natural bond orbital analysis, which is based on optimized geometric structures, was used to explore the interaction of L1/M2+, L2/M2+ molecules. The absorption spectra of L1, L2, L1/M2+, and L2/M2+, and their excited states were studied by time‐dependent density functional theory. A new type molecular device L2(2,2′‐dipyridine‐embedded N‐(9‐pyrenyl methyl)aza‐15‐crown‐5) is designed, which not only has the selectivity for Sr2+, and construct allosteric switch, but also has fluorescent sensor performance.

Photochromic behavior of triangle trithiophene with π-extension at the bridge unit

ABSTRACTA photochromic triangle terthiophene with phenylethynyl attached was synthesized under Sonogashira coupling condition and fully characterized. The photochromic behavior was investigated in typical solvents. In hexane, the reversibly photochromic process was induced by UV and Visible light. The solution color could be toggled between colorless and pink color. The photo- and thermo-stability were also investigated at 273 and 323 K. It is stable in the dark at the room temperature, while the degradation accelerated with the temperature rising. Correspondingly, the optimized geometry structure and frontier molecular orbitals were calculated. Both the distance between reactive carbon atoms and the HOMO distribution of ring-open form support the photo-cyclization reaction.

Photochromic behavior of 2,3-bis(2,5-dimethylthiophene-3-yl)thiophene-5-carbaldehyde oxime

ABSTRACTPhotochromic diarylethene oxime isomers were obtained by coupling between hydroxylamine hydrochloride and 2,3-bis(2,5-dimethylthiophene-3-yl)thiophene-5-carbaldehyde. The two isomers were confirmed by NMR. Photochromic behavior was investigated in THF. Reversible photochromism could be induced by alternated UV/Visible light. The solution color also can be toggled between colorless and light purple. Corresponding photo- and thermo-stability measurements indicate that they are stable in the dark at room temperature. However, the degradation of the two isomers is accelerated with the temperature rising and prolonged exposure to UV light. Optimized geometry structure and frontier molecular orbitals further supported their photochromic activity.

Exploration of photonic crystal circulator based on gyromagnetic properties and scaling of ferrite materials

Three port optical circulators are designed predicated on two dimensional triangular lattice photonic crystals and examined with different size of regular (circular) and irregular (triangular) ferrite posts, through the structure optimization and exploration of defect mode coupling. Ferrite, a special type of highly permeable and low-loss magnetic material, which is anisotropic when biased by a much larger static magnetic field is modeled and the gyromagnetic property of the same is investigated. According to theoretical analysis, the optimized geometry structure can make the non-reciprocal transmission of electromagnetic waves accompanying a high caliber isolation and low insertion loss with the avail of ferrite post inserted at the center of the joint. In order to minimize the reflections in the isolated port at the nominal frequencies, the scaling of ferrite post is implemented by defining S parameter. The structural optimization and the calculation of tensor elements of the anisotropic medium is executed by the finite element method. Moreover, the further study shows the importance of scaling the magneto-photonic material and the way it affects the transmission and isolation of the structured contrivance. Numerical simulations are performed to manifest the attainability and the characteristics of the designed circulators. Finally the triangular ferrite post with the scale of 0.518 makes the non-reciprocal transmission of electromagnetic waves with the minimum insertion loss at the normalized frequency range of 191.6GHz which benefits from a broad operational bandwidth. This optimized device can realize the operations of splitting, routing and isolation and have good technological compatibility for chip level integration into Photonic Integrated Circuits.