Δn Values Research Articles

Investigation of adsorption behavior of penicillamine anticancer drug upon B12P12, Ga12P12, and B6Ga6P12 fullerene-like nano-cages: A DFT insight

In this study, the interaction of Penicillamine anticancer drug with the B12P12, Ga12P12, and B6Ga6P12 nano-cages was studied using the DFT method. The negative values of Eads represent that the adsorption process is exothermic. The adsorption of PCA through the OH over nano-cages has a lower EG rather other atoms of PAC. The highest ΔN values in the PCA@B6Ga6P12 complex confirm the charge transfers from the PCA to the B6Ga6P12. The SE and SF configurations of the PCA@B6Ga6P12 complex have the highest E(2) and the PCA has a stronger interaction with the Gallium atom rather than the Boron atom. The highest and lowest recovery time value was observed for the SB of the PCA@Ga12P12 and SC of the PCA@B6Ga6P12. QTAIM analysis shows that the electrostatic interaction between nano-cages and PCA. Our results suggest that the B6Ga6P12 nano-cage is the better adsorbent for PCA due to lower EG and higher conductivity.

High-Δn tolane-liquid crystal diluters with low melting point and low rotational viscosity

High birefringence (Δn) and low melting point (Tm), high Δn and low rotational viscosity (γ1) are two pairs of contradictory performance parameters. In this work, two high-Δn LC diluters 3PTPF2V and 3PTPFOV are proposed to achieve a fine balance between them. These target compounds containing a rigid tolane core, a lateral fluorine substituent and a buty-3-enyl or allyloxy terminal group were further synthesized. Some experimental instruments, such as POM, DSC, Abbe refractometer, multi-channel liquid crystal evaluation system, were adopted to investigate their properties of mesomorphic phase behavior, Tm, Δn and γ1 by comparing with classical LC diluters 3HHV and V2PTP2V. Meanwhile, density functional theory (DFT) calculations were employed to correlate the experimental results, and their comprehensive effects on two high-Δn LC mixtures were further evaluated. Research results indicated that both target compounds possess low Tm (∼20 °C), low γ1 (∼6.5 mPa·s), and high Δn (>0.26). Performance in high-Δn LC mixture demonstrated that they could effectively decrease Tm and γ1, meanwhile maintain high Δn and Tc values, meaning their potential application prospects in fast-response LC optical devices.

Temperature dependence of the properties of the Li0.81Ag0.19InSe2 nonlinear crystal

The factors that determine the prospects of a crystal for frequency conversion of laser radiation in a wide range to the mid and far infrared (IR) ranges are nonlinear parameters and laser damage threshold (LDT). The latter is determined by the band gap and thermophysical characteristics. This work was devoted to studying the features of the structure change of the Li0.81Ag0.19InSe2 crystal in the temperature range 90–490 K. The temperature dependences of the thermal expansion coefficients, dispersion and optical characteristics in this range were studied. A relationship between the temperature change in the structure and other parameters has been established. In Li0.81Ag0.19InSe2 crystals, pyroluminescence was observed during heating or cooling in the range of 100–300 K, which indicates the crystal is attributed to pyroelectrics. The dispersion characteristics (nx, ny and nz) for wavelengths of 2 and 7 μm were studied, the values of birefringence Δn (nz - nx) were calculated in the temperature range 300–500 K. The detected fluctuations of Δn in the temperature range from 300 to 478 K may be associated with structural changes.

Synthesis and properties of biphenyl liquid crystal diluters terminated by 2,2-difluorovinyloxyl for high birefringence liquid crystals

ABSTRACT A series of liquid crystal (LC) diluters containing a rigid biphenyl core with a lateral fluorine substituent, a 2,2-difluorovinyloxyl terminal group and a flexible n-alkyl chain were designed and synthesised through classical organic synthetic reactions. Their chemical structures were characterised and confirmed by traditional methods. Meanwhile, the effects of alkyl-chain length, terminal group and lateral fluorine substituent on the melting point (T m), birefringence (Δn), dielectric anisotropy (Δε) and rotational viscosity (γ 1) of LC diluters were investigated. Density functional theory (DFT) calculations were employed to obtain the molecular polarisability, dipole moment, frontier orbitals, biphenyl dihedral angle and aspect ratio. Furthermore, their comprehensive properties in low-Δn LC mixture 002 and high-Δn LC mixture P01-F were further evaluated, and it was found that the 2,2-difluorovinyloxyl LC diluter 3FV have a significant advantage in reducing the T m and γ 1 of LC mixtures, and increasing the values of Δn and Δε. The research results provide technical support and theoretical guidance for the molecular design of new LC diluters and the development of fast response liquid crystals.

Benzoxazole-terminated liquid crystals with large birefringence and negative dielectric anisotropy

We synthesized heterocyclic liquid crystals with large birefringence and negative dielectric anisotropy, namely, 5–4-(2-(4-(alkoxy)phenyl)-2,3-difluorophenyl)benzo(d)oxazole derivatives (nPFO). These compounds display enantiotropic nematic mesophases with wide mesophase range of 45.9–84.0 °C (heating process) and 61.3–119.6 °C (cooling process). Compared with reference analogues of traditional benzoxazole compound 6PFB with different orientation of benzoxazole-terminated structure, the compounds nPFO roughly give lower melting points and clearing points because of their increased dihedral angle. Meanwhile, compounds nPFO show obviously large birefringence (Δn, 0.28–0.39 and 0.39–0.48 for experimental measurement and DFT theoretical calculation, respectively) due to the enhanced π-conjugation caused by the ethynyl bridge group in molecules. Benefitting from the larger perpendicular dipole moments and orientation angles, nPFO displays negative dielectric anisotropy (Δɛ) ranging from −3.60 to −4.10. These compounds can endow a commercial negative LC mixture the larger Δn and higher values of figure of merit, suggesting they are suitable dopant to further improve the performance of some commercial LC mixtures.

Bilateral filter denoising of Lidar point cloud data in automatic driving scene

3D Lidar has been widely used in auto drive systems owing to its high resolution, strong imaging ability, and long detection distance. The point cloud data (PCD) is generated by scanning the surrounding environment with 3D Lidar, providing a basis for decision-making and control of unmanned driving. However, the PCD is inevitably polluted by noise because traffic condition is complex and changeable, reducing the accuracy of environmental perception. The research on bilateral filtering of PCD in the automatic driving scene was carried out. The automatic driving experiment system is constructed. The campus scene is scanned by 16 Lidar lines. Four PCD traffic scene maps are obtained, consisting of bicycles, vehicles coming from the opposite side, many pedestrians, and vehicles parking on both sides of the road, respectively. Then, four point cloud maps are added with Gaussian noise. The effect of the parameters, i.e., the number of nearest neighboring points N, European distance weight Δd, and normal direction distance weight Δn on denoising, are researched. The experimental results show that the filtering effect is the best when N, Δd, and Δn are set to 10, 0.05, and 20, respectively. The signal-to-noise ratio is reduced by 5.6 dB on average. The values of N have little effect on the denoising results. However, the values of Δd and Δn have significant effects on denoising results. The results of this research can be used as an important reference for point cloud signal processing in other fields.

Effect of femtosecond laser irradiation on structure‐terahertz property relationship in sodium borosilicate glasses

AbstractWe report the effect of high‐repetition rate femtosecond (fs) laser irradiation on structure‐terahertz (THz) property relationship for sodium borosilicate glasses. We have used nuclear magnetic resonance (NMR), terahertz time‐domain spectroscopy (THz‐TDS), and Raman spectroscopy to examine pristine and laser irradiated regions of these glasses to determine and quantify boron speciation, THz refractive index, n(THz), and change (Δn) in n(THz), and spectral, that is, structural, changes due to laser exposure, respectively. Our results suggest that laser irradiation‐induced Δn(THz) values are dependent upon the glass composition, structural units, connectivity, and network, for example, the corresponding K‐ and R‐values of the borosilicate glass. Depolymerized glass networks show no changes in NMR B4 signal, slight changes in Raman spectral changes related to silicate structural units, for example, increase in Q3 tetrahedra with one nonbridging oxygen (nbO) atom, and higher measurable n(THz) and Δn(THz). More polymerized glasses, on the other hand, show changes in NMR B4 signal, varying degrees of Raman spectral changes in the borate subnetwork and structural units, and lower n(THz) and Δn(THz). The THz refractive index is most sensitive to modifier ions in the glasses, which are directly responsible for nbO formation, glass structure, and network polymerization.

A General Use QSAR-ARX Model to Predict the Corrosion Inhibition Efficiency of Drugs in Terms of Quantum Mechanical Descriptors and Experimental Comparison for Lidocaine.

A study of 250 commercial drugs to act as corrosion inhibitors on steel has been developed by applying the quantitative structure-activity relationship (QSAR) paradigm. Hard-soft acid-base (HSAB) descriptors were used to establish a mathematical model to predict the corrosion inhibition efficiency (IE%) of several commercial drugs on steel surfaces. These descriptors were calculated through third-order density-functional tight binding (DFTB) methods. The mathematical modeling was carried out through autoregressive with exogenous inputs (ARX) framework and tested by fivefold cross-validation. Another set of drugs was used as an external validation, obtaining SD, RMSE, and MSE, obtaining 6.76%, 3.89%, 7.03%, and 49.47%, respectively. With a predicted value of IE% = 87.51%, lidocaine was selected to perform a final comparison with experimental results. By the first time, this drug obtained a maximum IE%, determined experimentally by electrochemical impedance spectroscopy measurements at 100 ppm concentration, of about 92.5%, which stands within limits of 1 SD from the predicted ARX model value. From the qualitative perspective, several potential trends have emerged from the estimated values. Among them, macrolides, alkaloids from Rauwolfia species, cephalosporin, and rifamycin antibiotics are expected to exhibit high IE% on steel surfaces. Additionally, IE% increases as the energy of HOMO decreases. The highest efficiency is obtained in case of the molecules with the highest ω and ΔN values. The most efficient drugs are found with pKa ranging from 1.70 to 9.46. The drugs recurrently exhibit aromatic rings, carbonyl, and hydroxyl groups with the highest IE% values.

Opto-Thermo-Mechanical Characterization of Crazing Phenomena Observed for Isotactic Polypropylene Fibers Using Digital Photoelasticity and the Computed Tomography Techniques

Digital photoelasticity was used to characterize the crazing phenomena of isotactic polypropylene (iPP) fibers as a precursor of fracture processes. In this study, the effect of stretching at different rates on the formation of crazes was investigated for the iPP fibers. Also, the influence of drawing the iPP fibers at different temperatures on the formation of the crazes was studied. In addition, the effect of heating the crazed iPP fibers on the formed crazes was characterized using digital photoelasticity. Computed tomography was used to obtain qualitative and quantitative measurements of the crazes densities along the cross-sections of the iPP fibers. Also, the birefringence (Δn) values of the crazes were measured for different conditions of stretching and temperature and compared to the Δn of the bulk material. The photoelastic patterns of the iPP fibers are given for illustrating the crazes behavior in the iPP fibers.

Epigenetically modified nucleobases (5hmc, 5fc, and 5caC) interaction with boron and nitrogen doped porous graphene (B/N-pGr) as promising materials for biosensing application: A density functional theory calculations

In this present work, porous graphene (pGr), boron (B-pGr), and nitrogen (N-pGr) doped porous sheets are explored as a bio-sensor device for sensing modified nucleobases (MBs) in cancer therapy using density functional theory (DFT). The obtained geometrical, energetic and electronic properties revealed that the B-pGr is highly reactive and it adsorbs MBs better than the pGr and N-pGr, because B atom holds empty p-orbitals which easily interact with partially filled p-orbital of N and O atom. Thus, the adsorption energies of 5hmc, 5caC, and 5fc on B-pGr are high rather than the pGr and N-pGr. The corresponding adsorption energies are −96.074, −77.0, and −60.721 kcal/mol for 5hmc, 5caC, and 5fc respectively. The positive signature of ΔN values (0.005 eV, 0.076 eV, and 0.047 in MBs on pGr and 0.171 eV, 0.252 eV and 0.205 eV in MBs on N-pGr) are obtained at MBs on pGr and N-pGr complex. The negative ΔN values (−0.141 eV, −0.032 eV, and −0.061 eV in MBs on B-pGr) are obtained at MBs of B-pGr. The calculated absorption values shows that the B-pGr is strongly adsorbed MBs at 342 nm. The obtained results exhibit that the B-pGr sheet retains significant therapeutic potential as a bio-sensing application for cancer therapy.

Measurements of microwave and NMR spectra for 15N substituted formamidinium formate

A sample of doubly-substituted 15N formamidinium formate was synthesized and the microwave spectrum was measured in the 5.6–14.2 GHz frequency range using a Flygare-Balle type pulsed beam Fourier transform microwave (MW) spectrometer. A total of 13 a-type rotational transitions were measured and fitted to obtain the rotational constants and centrifugal distortion constants for the15N substituted isotopologue. The rotational constants and centrifugal distortion constants determined have the following values: A = 5808.02(18) MHz, B = 2127.008(2) MHz, C = 1557.615(2) MHz, DJ = 0.60(11) kHz, DJK = 4.95(71) kHz and DK = −0.138(24) kHz. Tunneling splittings were searched for, but not observed. NMR spectra for this compound are reported including values of δC, δN, 1JCH, 1JCN and 2JNH in CD3SOCD3, CD3OD and D2O. The occurrence of NH to ND exchange in D2O allowed the fortuitous measurement of 1JND.

Classical calculation of radiative decay rates of hydrogenic Stark states

The Kepler–Coulomb problem is solved in parabolic coordinates and the Larmor radiation problem is analyzed to complement a previous study performed for the usual representation in spherical polar coordinates. The problem is then extended to include a weak electric field and a solution in terms of action-angle variables is provided. A comparison with quantum spontaneous decay rates shows that for azimuthal quantum number m = 0 states only transitions to nearby n −Δn principal quantum number states are described properly by the Wentzel–Kramers–Brillouin (WKB) quantized classical motions, but that for m > 0 reasonable results emerge for many values of Δn. A simple approximate expression for the lifetime of m ≠ 0 states emerges from the semi-classical analysis.

Optical Properties, Excess Volume Prediction from Refractive Index and Intermolecular Interactions in Dibutylamine + Isomeric Butanol

The alkyl or alkanol amines are widely used as absorbent for CO2 capture owing to interaction between amines and CO2. In order to increase the CO2 loading in amine based absorbents, blending of amine with alkanol may be one option. As thermophysical properties of of utmost importance in designing, in present work, the refractive index of dibutylamine (DBA) and isomeric butanol as well as their binary mixtures at 298.15 K to 308.15 K were measured. The Δn are found positive for DBA + isomeric butanol mixtures. The Δn values were correlated with Redlich-Kister polynomial. The refractive index data were also predicted by various correlations and results were expressed in terms of standard deviation. The Δn values were also employed to calculate the excess molar volume of the present binary mixtures. Further Δn data analysed in terms of intermolecular interaction among DBA (1) + isomeric butanol (2) mixtures.

Optical Studies of Binary Mixture of Chloro Substituted Benzene and n-Hexane or Cyclohexane or 1,4-Dioxane

Thermophysical properties of binary liquid mixtures are highly beneficial for getting information about the intermolecular interactions and geometrical effects in the system. The chloro-substituted benzene compounds like 2-chlorotoluene, 4-chlorotoluene, 1,3-dichlorobenzene also have wide range of industrial and biomedical areas. In present work, the refractive indices (n) of haloarenes, hydrocarbons, ether, and respective possible binary mixtures were experimentally determined over the entire compositions at T= (298.15-318.15) K. The mixtures selected were 2-chlorotoluene or 4-chlorotoluene or 1,3-dichlorobenzene (1) + n-hexane or cyclohexane or 1,4-dioxane (2) with its possible combinations. The Δn is positive for all binary mixtures at all investigated compositions. Different rules of mixing like Lorentz-Lorentz, Erying-John, Arago-Biot, etc. were also used to predict n values. The Δn values were also analyzed in terms of ongoing intermolecular interactions among the components of the selected system.

Preparation and properties of high refractive index polythioetherimide film based on thiol-ene click chemistry

Three kinds of biscitraconimide (BCI) monomers, 4,4′-(diaminodiphenylsulfone) biscitraconimide (DDS-BCI), 1,2-(ethylenediamine) biscitraconimide (EDA-BCI) and m-(xylylenediamine) biscitraconimide (MXDA-BCI), were respectively prepared from the reaction of citraconic anhydride with three different diamines by reflux dehydration in glacial acetic acid. As-prepared products further reacted with 4,4′-thiodibenzenethiol (TDBT) and 1,6-hexanedithiol (HDT) to synthesize a series of new transparent thermoplastic polythioetherimides (PTEI) films with excellent solubility, high refractive index and low birefringence. All PTEI films had the 5% weight loss temperature between 332 °C and 417 °C and the thermal expansion coefficient ranged from 39.4–94.8 ppm/°C, showing good thermal stability. Besides, the transmittance of PTEI film at 450 nm exceeded 85 %, the average refractive index (nav) measured at 589 nm reached up to 1.6236 ∼1.6635 and in-plane/out of-plane birefringence (Δn) values were between 0.0014 and 0.0036. Especially DDS-BCI/TDBT sample exhibited the highest refractive index, relatively small birefringence and excellent thermal stability among all PTEI films, which is expected to be an ideal advanced optical material.

Thermophysical properties of ternary liquid mixture of diisopropyl ether (1) + ethanol (2) + n-heptane (3): Measurement and correlation

Densities (ρ), speeds of sound (u) and refractive indices (n) of system containing diisopropyl ether, ethanol and n-heptane were measured at temperature 298.15 K to 318.15 K and at pressure 0.1 MPa. The values of excess molar volume (VmE), deviation in speed of sound (Δu), deviation in refractive index (Δn), excess isentropic compressibility (κsE), excess intermolecular free length (LfE), and excess available volume (VaE) of the system were calculated using measured data of densities, speeds of sound and refractive indices. The VmE values were fitted to the Singh, Cibulka and Nagata equations. Several analytical models like Rastogi model, Kohler model, Tsao-Smith model, Radojkovic model and Jacob-Fitzner model were applied to estimate VmE values. The values of Δu, κsE, LfE, VaE and Δn were also fitted to the Singh equation. Different correlations and models were applied for estimation of speed of sound and refractive index values.

Thermodynamics of molecular interaction of ternary mixture containing ethanol, n-heptane and n-octane at 298.15, 308.15 and 318.15 K

In this research article, densities (ρ), speeds of sound (u) and refractive indices (n) of the ternary liquid mixture of oxygenated fuel additive (ethanol) and aliphatic hydrocarbons (C7, C8) were experimentally measured at different temperatures (T = 298.15 K to 318.15 K) and pressure of 0.1 MPa over whole composition range. Excess molar volume (VmE), excess ultrasound speed (uE), excess isentropic compressibility (ksE), excess intermolecular free length (LfE), excess available volume (VaE) and deviation in refractive index (Δn) of the ternary mixture were evaluated using experimental data. The VmE values were fitted to the Singh, Nagata and Cibulka equations and also interpreted using Prigogine-Flory-Patterson (PFP) theory. Various geometrical solution models like Tsao-Smith model, Kohler model, Rastogi model, Jacob-Fitzner model, and Radojkovic model were used to predict VmE values. The uE, ksE, LfE, VaE and Δn values were also fitted to the Singh equation. Various correlations and mixing rules were used for theoretical prediction of u and n values. Temperature effects on various thermodynamic properties were also studied. The values of VmE, uE, ksE, LfE, VaE and Δn were interpreted in terms of molecular interactions in between the fuel additive and hydrocarbons.

Identification of N‐ or O‐Alkylation of Aromatic Nitrogen Heterocycles and N‐Oxides Using 1H–15N HMBC NMR Spectroscopy

A series of representative diazines and pyridine N‐oxides were subjected to alkylation using several different alkylating agents. The 15N NMR chemical shifts (δN values) of the diazines, pyridine N‐oxides and derived alkylation products were determined using 1H‐15N HMBC NMR spectroscopy at natural 15N abundance. The changes in the 15N NMR chemical shifts (Δ(δN) values) that occurred on going from starting materials to products in these reactions were analyzed. N‐alkylation of diazines resulted in large upfield shifts of the δN values of the alkylated nitrogen (of the order of 100 ppm or greater). While O‐alkylation of pyridine N‐oxides resulted in upfield shifts of the δN values of the N‐(alkoxy)pyridinium nitrogen, the Δ(δN) values were of a much smaller magnitude (ca. –42 ppm) than those observed for N‐alkylations of diazines. Nitrogen NMR spectroscopic data from the literature of relevance to alkylation of azines, diazines, azine N‐oxides and diazine N‐oxides was gathered together, and using this in tandem with our 15N NMR spectroscopic data, we have been able to corroborate our observations on the trends observed in the Δ(δN) values associated with N‐ and O‐alkylation reactions of aromatic N‐heterocycles and N‐oxides. An analysis protocol that relies on synergistic evaluation of 1H‐15N HMBC and 1H‐13C HMBC NMR spectra has been developed that enables unambiguous diagnosis of the occurrence of N‐alkylation of aromatic N‐heterocycles and O‐alkylation of aromatic N‐oxides.

Tilted black-Si: ∼0.45 form-birefringence from sub-wavelength needles.

The self-organised conical needles produced by plasma etching of silicon (Si), known as black silicon (b-Si), create a form-birefringent surface texture when etching of Si orientated at angles of θi < 50 - 70° (angle between the Si surface and vertical plasma E-field). The height of the needles in the form-birefringent region following 15 min etching was d ∼ 200 nm and had a 100 μm width of the optical retardance/birefringence, characterised using polariscopy. The height of the b-Si needles corresponds closely to the skin-depth of Si ∼λ/4 for the visible spectral range. Reflection-type polariscope with a voltage-controlled liquid-crystal retarder is proposed to directly measure the retardance Δn × d/λ ≈ 0.15 of the region with tilted b-Si needles. The quantified form birefringence of Δn = -0.45 over λ = 400 - 700 nm spectral window was obtained. Such high values of Δn at visible wavelengths can only be observed in the most birefringence calcite or barium borate as well as in liquid crystals. The replication of b-Si into Ni-shim with high fidelity was also demonstrated and can be used for imprinting of the b-Si nanopattern into other materials.

Development of Novel Triazine-Based Poly(phenylene sulfide)s with High Refractive Index and Low Birefringence.

High-refractive-index (high-n) polymers with a high optical transparency and low birefringence (Δn) have been desired in progressive optoelectronic devices. However, the trade-off between high-n and low-Δn remains a challenge at present. Here, the development of a novel array of high-n, high-sulfur-containing, highly transparent, colorless poly(phenylene sulfide) (PPS) polymers bearing triazine units in the main chains is reported. Six new triazine monomers T1–T6 with various pendant groups via different linkers (−O– and −NH−) could be prepared for developing PPSs with high-n and low Δn values. These PPSs (P1–P6) were obtained by the polycondensation of T1–T6 with commercial aromatic dithiol, 4,4′-thiobisbenzenethiol, respectively, which showed very high-n values (nav: 1.6902–1.7169 at 633 nm), high optical transparency (T % > 90% @ 400 nm), and low birefringence (Δn = 0.0015–0.0042). All the PPSs displayed high n∞ values (1.6340–1.6654), providing valuable information for the development of high-n triazine-based PPS materials for application not only in the visible region but also in the near-infrared region.