Search Results (38)

The aim of this study was to examine the functional characteristics of the process of cutting surgical gauze with a drum cutting unit. For this purpose, the authors designed and constructed a test stand on which experimental tests were conducted. As part of this study, the results of the experimental tests are presented, which were conducted for three selected thicknesses of surgical gauze samples, four selected angles of feeding of the material to be cut and nine selected cutting speeds. In order to determine cutting resistance, the specific cutting resistance was used, and the energy consumption was estimated using the specific cutting work related to the cutting surface of the surgical gauze. The conducted experimental studies demonstrated that the highest value of the specific cutting resistance $p_c=78.14 \mathrm{N}\cdot {\mathrm{m}}^{-1}$ occurred during the cutting of eight-layer gauze at a cutting angle $\alpha =0°$ and a cutting speed $V_c=0.66 \mathrm{m}\cdot {\mathrm{s}}^{-1}$. Meanwhile, the highest value of the specific cutting work was approximately $L_{jS}=120.00 \mathrm{J}\cdot {\mathrm{m}}^{-2}$ during the cutting of three-layer gauze, also at a cutting speed $V_c=0.66 \mathrm{m}\cdot {\mathrm{s}}^{-1}$ for cutting angles $\alpha =0°$ and $\alpha =5°$. This study found that $V_c=0.66 \mathrm{m}\cdot {\mathrm{s}}^{-1}$ is the threshold cutting speed at which the material is cut. Below this speed, the cutting drum does not have enough momentum to cut the material. Based on the statistical analysis of the obtained test results, it was concluded that there exists a relationship between the independent and dependent variables. The cutting speed has the greatest impact on the parameters of the surgical gauze cutting process. The test results, which have not been found in the worldwide literature to date, constitute a valuable contribution to the development of the theory of surgical gauze cutting. The experimentally determined specific cutting resistance p_c and specific cutting work of surgical gauze broaden the knowledge of the materials used in medicine and contribute to the expansion of scientific knowledge in this field. Full article

Graffiti’s dual existence as both public art and illicit practice has generated sustained legal, cultural, and aesthetic debates. This article examines the role of anonymity in shaping how graffiti is recognized, regulated, and interpreted within both legal frameworks and artworld aesthetics. Focusing on the legal battle over 5Pointz, a prominent New York graffiti site that was whitewashed in 2013 and demolished in 2014, I analyze how the Cohen v. G&M Realty L.P. case reveals a structural tension between graffiti’s collective ethos and the legal system’s emphasis on identifiable authorship. Drawing upon legal studies, urban cultural theory, and aesthetics, this article explores how the Visual Artists Rights Act (VARA) mediated the legal recognition of graffiti, often privileging curated, institutionally sanctioned works while rendering anonymous street art legally vulnerable. I further synthesize scholarly perspectives on 5Pointz to highlight how legal discourse constructs and delimits the status of graffiti within public spaces. Ultimately, I argue that anonymity functions not simply as an absence of authorship but as an aesthetic and political mode of experiencing the object, one that challenges traditional frameworks of artistic attribution and cultural legitimacy. By interrogating the legal and ideological forces that shape graffiti’s recognition, this article situates anonymity as a central, yet often overlooked, feature of graffiti’s critical and aesthetic power. Full article

Hydantoins, a class of five-membered heterocyclic compounds, exhibit diverse biological activities. The aim of this study was to synthesize and characterize a series of novel 3,5-disubstituted hydantoins and to investigate their antiproliferative activity against human cancer cell lines. The new hydantoin derivatives 5a–i were prepared as racemic mixtures of syn- and anti-isomers via a base-assisted intramolecular amidolysis of C-3 functionalized β-lactams. The enantiomers of syn-5a and anti-hydantoins 5b were separated by preparative high-performance liquid chromatography (HPLC) using n-hexane/2-propanol (90/10, v/v) as the mobile phase. The absolute configuration of the four allyl hydantoin enantiomers 5a was assigned based on a comparison of the experimental electronic circular dichroism (ECD) and vibrational circular dichroism (VCD) spectra with those calculated using density functional theory (DFT). The antiproliferative activity evaluated in vitro against three different human cancer cell lines: HepG2 (liver hepatocellular carcinoma), A2780 (ovarian carcinoma), and MCF7 (breast adenocarcinoma), and on the non-tumor cell line HFF1 (normal human foreskin fibroblasts) using the MTT cell proliferation assay. In silico drug-like properties and ADMET profiles were estimated using the ADMET Predictor ver. 9.5 and the online server admetSAR. Eighteen new 3,5-disubstituted hydantoins were synthesized and characterized. The compound anti-5c showed potent cytotoxic activity against the human tumor cell line MCF7 (IC₅₀ = 4.5 µmol/L) and the non-tumor cell line HFF1 (IC₅₀ = 12.0 µmol/L). In silico analyzes revealed that the compounds exhibited moderate water solubility and membrane permeability and are likely substrates for CYP3A4 and P-glycoprotein and have a high probability of antiarthritic activity. Full article

In this study, Ce₂[Zr_1−x(Ba_1/3Nb_2/3)_x]₃(MoO₄)₉ (0.02 ≤ x ≤ 0.1, CZ_1−xN_x) ceramics were sintered at 600 °C and 700 °C using the traditional solid-state method. An analysis conducted through XRD and Rietveld refinement confirmed that all the CZ_1−xN_x ceramics displayed a single phase with a trigonal structure (space group R-3c). The observed increases in cell volume with increasing x values indicate the successful substitution of (Ba_1/3Nb_2/3)⁴⁺. The high densification of the synthesized phase was validated by the density and SEM results. Additionally, the P-V-L theory demonstrates a strong correlation between the Ce-O bond and ε_r, as well as τ_f, and between the Mo-O bond and Q×f. Notably, the CZ_0.98N_0.02 ceramics demonstrated superior performance at 675 °C, exhibiting ε_r = 10.41, Q×f = 53,296 GHz, and τ_f = −23.45 ppm/°C. Finally, leveraging CZ_0.98N_0.02 ceramics as substrate materials enabled the design of a patch antenna suitable for the 5G communication band, demonstrating its significant potential in this field. Full article

Integral equations, which are defined as “the equation containing an unknown function under the integral sign”, have many applications of real-world problems. The second type of Fredholm integral equations is generally used in radiation transfer theory, kinetic theory of gases, and neutron transfer theory. A special case of these equations, known as the quadratic Chandrasekhar integral equation, given by $x\left(s\right)=1+\lambda x\left(s\right){\int }_0^1\frac{s}{t+s}x\left(t\right)dt,$ can be very often encountered in many applications, where x is the function to be determined, $\lambda$ is a parameter, and $t,s\in [0,1]$. In this paper, using a fixed-point theorem, the existence conditions for the solution of Fredholm integral equations of the form $\chi \left(l\right)=\varrho \left(l\right)+\chi \left(l\right){\int }_p^{q}k(l,z)\left(V\chi \right)\left(z\right)dz$ are investigated in the space $C_{\omega }\left[p,q\right],$ where $\chi$ is the unknown function to be determined, V is a given operator, and $\varrho ,k$ are two given functions. Moreover, certain important applications demonstrating the applicability of the existence theorem presented in this paper are provided. Full article

A new structurally simple fluorescent CP probe based on chromone was designed and synthesized, and its structure was fully characterized using various analytical techniques. The CP probe displays a high selectivity and sensitivity for sensing Fe³⁺ with a “turn-off” fluorescence response over other metal ions in a DMSO/H₂O (4:1, v/v) solution. The experiment results show that the CP probe is stable over a wide pH range of 2.0–12.0. The detection limit for Fe³⁺ was calculated to be 0.044 μmol•L⁻¹. The molar ratio method indicated that the binding mode between the CP probe and Fe³⁺ is a 1:1 complex formation. HR-MS and density functional theory (DFT) calculations were also performed to further confirm the recognition mechanism. Both fluorescence imaging experiments and the MTT assay demonstrated that the CP probe was suitable for detecting intracellular Fe³⁺ and no significant cytotoxicity in living cells. Full article

The effect of the variability in a layered structure, characterized by the spatial variability of the saturated hydraulic conductivity, on the distribution of a pressure head $p$ in a foundation subjected to water level fluctuation in a reservoir is investigated with the aid of the random field theory, Karhunen–Loève (K-L) expansion, first-order moment approach, and cross-correlation analysis. The results show that the variability in the foundation structure has significant impacts on the groundwater response to the reservoir’s water level fluctuations. Regions with relatively large uncertainties of the $p$ and ${\sigma }_p$ values in the foundation are those around the initial water level at the reservoir side, and those at the distal end away from the reservoir. In addition, there is a larger variance of $K_s$, denoted as ${\sigma }_{ln{K}_s}^2$, a larger correlation scale in the horizontal direction ${\lambda }_h$, a larger correlation scale in the vertical direction ${\lambda }_v$, and a larger one-way time consumption of fluctuations T to a larger uncertainty in $p$. Moreover, the four factors (${\sigma }_{ln{K}_s}^2$, ${\lambda }_h$, ${\lambda }_v$, and $T$) all have positive correlations with ${\sigma }_p$. ${\sigma }_{ln{K}_s}^2$ has the largest impact on ${\sigma }_p$ in the foundation, ${\lambda }_v$ has the second largest impact, and ${\lambda }_h$ has the smallest impact. A foundation with small $K_s$ values around the initial water level at the reservoir side and large $K_s$ values around the highest water level at the reservoir side may produce larger $p$ values in the foundation. These results yield useful insight into the effect of the variability in a layered structure on the distribution of the pressure head in a foundation subjected to water level fluctuation in a reservoir. Full article

This study utilizes Aspen Plus chemical process simulation software (V11), applies uniform nucleation theory and growth kinetics equations, and explores the particle formation mechanism of TiCl₄ hydrolysis to prepare nano TiO₂. In the water/ethanol system, the effects of the reaction time, reaction temperature, water addition, pH value, and ethanol amount on the crystal nucleation rate and TiO₂ particle distribution (PSD) were studied in detail by adding triethanolamine dropwise and using the Aspen Plus chemical process software simulation calculation method. The calculation results indicate that at room temperature, the formation of TiO₂ crystal nuclei mainly occurs in the first 300 s and then enters the growth stage. The reaction was carried out under neutral conditions at room temperature for 4 h in 1 mL TiCl₄, 6 mL C₆H₁₅NO₃, 15 mL H₂O, and 30 mL C₂H₅OH. The maximum number of particles reached 195 mesh per cubic micrometer, and the particle size after crystal nucleus growth was smaller, with a D₅₀ of 6.15 nm. The distribution curve shows a normal distribution, which is basically consistent with the experimental results. When studying various factors, it was found that controlling the reaction time within 60 min and maintaining the reaction temperature at room temperature can reduce the particle size D₅₀ to 2.44 nm. Continuing to adjust the amount of water added, it was found that at 1 mL, D₅₀ decreased again to 0.19 nm. Adjusting the pH value found that maintaining the neutrality did not change the particle size. Continuing to adjust ethanol, it was found that adding an appropriate amount of ethanol promoted nucleation and growth. At 4 mL, the maximum number of particles reached 199 mesh per cubic micrometer, but D₅₀ slightly increased to 0.24 nm. Full article

The lattice dynamical properties of dilute InAs_1−xN_x/InP (001) epilayers (0 ≤ x ≤ 0.03) grown by gas-source molecular beam epitaxy were carefully studied experimentally and theoretically. A high-resolution Brüker IFS 120 v/S spectrometer was employed to measure the room-temperature infrared reflectivity (IRR) spectra at near-normal incidence (θ_i = 0). The results in the frequency range of 180–500 cm⁻¹ revealed accurate values of the characteristic In-As-like and In-N-like vibrational modes. For InAs_1−xN_x alloys, a classical “Drude–Lorentz” model was constructed to obtain the dielectric functions $\tilde{\mathsf{\epsilon }}\left(\mathsf{\omega }\right)$ in the far IR regions by incorporating InAs-like and InN-like transverse optical ${\mathsf{\omega }}_{\mathrm{T}\mathrm{O}}$ modes. Longitudinal optical ${\mathsf{\omega }}_{\mathrm{L}\mathrm{O}}$ phonons were achieved from the imaginary parts of the simulated dielectric loss functions. The theoretical results of IRR spectra for InAs_1−xN_x/InP (001) epilayers using a multi-layer optics methodology provided a very good agreement with the experimental data. At oblique incidence (θ_i ≠ 0), our study of s- and p-polarized reflectance (R_s,p(ω)) and transmission (T_s,p(ω)) spectra allowed the simultaneous perception of the ${\mathsf{\omega }}_{\mathrm{T}\mathrm{O}}$ and ${\mathsf{\omega }}_{\mathrm{L}\mathrm{O}}$ phonons of the InAs, InN and InAs_0.97N_0.03 layers. Based on the average t-matrix Green’s function theory, the results of local vibrational modes for light ${\mathrm{S}\mathrm{i}}_{\mathrm{I}\mathrm{n}}^{+}$ donors and ${\mathrm{S}\mathrm{i}}_{\mathrm{A}\mathrm{s}}^{-}, {\mathrm{C}}_{\mathrm{A}\mathrm{s}}^{-}$ acceptors in InAs were found in good agreement with the existing Raman scattering and infrared spectroscopy data. $\mathrm{I}\mathrm{n}\mathrm{I}\mathrm{n}\mathrm{N}$, however, the method predicted an in-band mode for the ${\mathrm{M}\mathrm{g}}_{\mathrm{I}\mathrm{n}}^{-}$ acceptor while projecting an impurity mode of the ${\mathrm{S}\mathrm{i}}_{\mathrm{I}\mathrm{n}}^{+}$ donor to appear just above the maximum ${\mathsf{\omega }}_{\mathrm{m}\mathrm{a}\mathrm{x}}^{\mathrm{I}\mathrm{n}\mathrm{N}}[\equiv 595 {\mathrm{c}\mathrm{m}}^{-1}$] phonon frequency region. In InAs_1−xN_x/InP (001) epifilms, the comparison of reflectivity/transmission spectra with experiments and the predictions of impurity modes for isoelectronic donor and acceptor impurities in InAs and InN can be valuable for appraising the role of defects in other technologically important semiconductors. Full article

A new copper(I) complex, [Cu₂(L)₂dppm](PF₆)₂ (1) [L = 3-(2-Pyridyl)-5,6-diphenyl-1,2,4-triazine and dppm: Bis(diphenylphosphino)methane], was prepared and characterized by IR, ¹H-NMR, ³¹P-NMR spectroscopy, elemental and thermogravimetric analysis, and a single-crystal X-ray diffraction technique. Complex 1 is a dinuclear compound, showing that L and dppm act as tridentate and bidentate chelating ligands, respectively. The two Cu(I) atoms exhibit a distorted tetrahedral coordination sphere embedded in N₃P environments. The supramolecular interactions in the solid-state structure are characterized by C−H···N, C−H···F, C-H···π and π···π intermolecular interactions, which we studied using Hirshfeld surface and fingerprint tools. Additionally, the complex was studied experimentally using UV–Vis spectroscopy and cyclic voltammetry, and theoretical studies with time-dependent density functional theory (TD-DFT) were performed. Moreover, the optical and electrochemical properties were studied, focusing on the band gap. Compound 1 was used as a co-sensitizer in a dye-sensitized solar cell, showing a good photovoltaic performance of 2.03% (Jsc = 5.095 mAcm⁻², Voc = 757 mV, and FF = 52.7%) under 100 mW cm⁻² (AM 1.5G) solar irradiation, which is similar to that of DSSC, which was only sensitized by N719 (2.2%) under the same condition. Full article

Two new vanadium (V) complexes involving 6-hexyl-4-(2-thiazolylazo)resorcinol (HTAR) and tetrazolium cation were studied. The following commercially available tetrazolium salts were used as the cation source: tetrazolium red (2,3,5-triphenyltetrazol-2-ium;chloride, TTC) and neotetrazolium chloride (2-[4-[4-(3,5-diphenyltetrazol-2-ium-2-yl)phenyl]phenyl]-3,5-diphenyltetrazol-2-ium;dichloride, NTC). The cations (abbreviated as TT⁺ and NTC⁺) impart high hydrophobicity to the ternary complexes, allowing vanadium to be easily extracted and preconcentrated in one step. The complexes have different stoichiometry. The V(V)–HTAR–TTC complex dimerizes in the organic phase (chloroform) and can be represented by the formula [(TT⁺)[VO₂(HTAR)]]₂. The other complex is monomeric (NTC⁺)[VO₂(HTAR)]. The cation has a +1 charge because one of the two chloride ions remains undissociated: NTC⁺ = (NT²⁺Cl⁻)⁺. The ground-state equilibrium geometries of the constituent cations and final complexes were optimized at the B3LYP and HF levels of theory. The dimer [(TT⁺)[VO₂(HTAR)]]₂ is more suitable for practical applications due to its better extraction characteristics and wider pH interval of formation and extraction. It was used for cheap and reliable extraction–spectrophotometric determination of V(V) traces in real samples. The absorption maximum, molar absorptivity coefficient, limit of detection, and linear working range were 549 nm, 5.2 × 10⁴ L mol⁻¹ cm⁻¹, 4.6 ng mL⁻¹, and 0.015–2.0 μg mL⁻¹, respectively. Full article

The synthesis and X-ray crystal structure analyses of the azido complex [Zn(N₃)(Arg)₂](N₃)·3H₂O, where Arg is L-arginine, were presented. The molecular structure of the complex was further studied using FT-IR spectra as well as atoms in molecules (AIM) theory. An analysis of the crystal data indicated monoclinic crystal system and P2₁ space group with a = 13.0283(5) Å, b = 15.2032(7) Å, c = 13.3633(6) Å, β = 114.3580(10)°, V = 2411.28(18) ų, and Z = 4. Two of the [Zn(N₃)(Arg)₂](N₃)·3H₂O formulae represent the asymmetric unit of this complex where the geometric parameters of both units are slightly different. In [Zn(N₃)(Arg)₂](N₃)·3H₂O, the central Zn(II) ion is penta-coordinated with two Arg molecules as a bidentate ligand and one terminally coordinated azide ion. Each of the two Arg molecules are located trans to one another and coordinated with the Zn(II) via the N and O atoms of the amino and carboxylate groups, respectively. Hence, Zn(II) is five-coordinated and has a distorted square pyramidal coordination geometry. The supramolecular structure of the [Zn(N₃)(Arg)₂](N₃)·3H₂O complex was inspected using the Hirshfeld analysis. The O···H (26.6–28.4%), H···H (32.3–35.3%), and N···H (30.4–34.0%) contacts are the most significant interactions in the crystal structure of the [Zn(N₃)(Arg)₂](N₃)·3H₂O complex. The Zn–N, and Zn–O bonds have slight covalent interactions based on the AIM study. Full article

This work studied the phase constitution, bond characteristics, and microwave dielectric performances of Sr₂TiO₄ ceramics. Based on XRD and Rietveld refinement analysis, pure tetragonal Ruddlesden–Popper type Sr₂TiO₄ ceramic is synthesized at 1425~1525 °C. Meanwhile, the microstructure is dense and without porosity, indicating its high sinterability and densification. Great microwave dielectric performances can be obtained, namely an ε_r value of 39.41, and a Q × f value of 93,120 GHz, when sintered at 1475 °C. Under ideal sintering conditions, the extrinsic factors are minimized and can be ignored. Thus, the intrinsic factors are considered crucial in determining microwave dielectric performances. Based on the P–V–L complex chemical bond theory calculation, the largest bond ionicity, and proportions to the bond susceptibility from Sr–O bonds suggest that Sr–O bonds mainly determine the dielectric polarizability. However, the Ti–O bonds show lattice energy about three times larger than Sr–O bonds, emphasizing that the structural stability of Sr₂TiO₄ ceramics is dominated by Ti–O bonds, and the Ti–O bonds are vital in determining the intrinsic dielectric loss. The thermal expansion coefficient value of the Sr₂TiO₄ structure is also mainly decided by Ti–O bonds. Full article

Ba_1−xSr_x(Zn_1/3Nb_2/3)O₃ (BSZN) perovskite ceramics are prepared using the traditional solid-state reaction method. X-ray diffraction (XRD), Scanning electron microscopy (SEM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS) were used to analyze the phase composition, crystal structure, and chemical states of BSZN ceramics, respectively. In addition, the dielectric polarizability, octahedral distortion, complex chemical bond theory, and PVL theory were investigated in detail. Systematic research showed that Sr²⁺ addition could considerably optimize the microwave dielectric properties of BSZN ceramics. The change in τ_f value in the negative direction was attributed to oxygen octahedral distortion and bond energy (E_b), and the optimal value of 1.26 ppm/°C was obtained at x = 0.2. The ionic polarizability and density played a decisive role in the dielectric constant, achieving a maximum of 45.25 for the sample with x = 0.2. The full width at half-maximum (FWHM) and lattice energy (U_b) jointly contributed to improving the Q × f value, and a higher Q × f value corresponded to a smaller FWHM value and a larger U_b value. Finally, excellent microwave dielectric properties (ε_r = 45.25, Q × f = 72,704 GHz, and τ_f = 1.26 ppm/°C) were obtained for Ba_0.8Sr_0.2(Zn_1/3Nb_2/3)O₃ ceramics sintered at 1500 °C for 4 h. Full article

After a brief introduction of Born’s reciprocal relativity theory is presented, we review the construction of the $deformed$ quaplectic group that is given by the semi-direct product of $U(1,3)$ with the $deformed$ (noncommutative) Weyl–Heisenberg group corresponding to $noncommutative$ fiber coordinates and momenta $[X_a,X_b]\ne 0$; $[P_a,P_b]\ne 0$. This construction leads to more general algebras given by a two-parameter family of deformations of the quaplectic algebra, and to further algebraic extensions involving antisymmetric tensor coordinates and momenta of higher ranks $[X_{a_1{a}_2\cdots a_n},X_{b_1{b}_2\cdots b_n}]\ne 0$; $[P_{a_1{a}_2\cdots a_n},P_{b_1{b}_2\cdots b_n}]\ne 0$. We continue by examining algebraic extensions of the Yang algebra in extended noncommutative phase spaces and compare them with the above extensions of the deformed quaplectic algebra. A solution is found for the exact analytical mapping of the noncommuting $x^{\mu },p^{\mu }$ operator variables (associated to an 8D curved phase space) to the canonical $Y^A,{\mathsf{\Pi }}^A$ operator variables of a flat 12D phase space. We explore the geometrical implications of this mapping which provides, in the $classical$ limit, the embedding functions $Y^A(x,p),{\mathsf{\Pi }}^A(x,p)$ of an 8D curved phase space into a flat 12D phase space background. The latter embedding functions determine the functional forms of the base spacetime metric $g_{\mu \nu }(x,p)$, the fiber metric of the vertical space $h^{ab}(x,p)$, and the nonlinear connection $N_{a\mu }(x,p)$ associated with the 8D cotangent space of the 4D spacetime. Consequently, we find a direct link between noncommutative curved phase spaces in lower dimensions and commutative flat phase spaces in higher dimensions. Full article