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741.
Vishwas Akavaram Kush Kumar Shreya Sriram Saisrinath Narra Akshant Kumawat Santosh Kumar Meena Karthik Pushpavanam 《Macromolecular bioscience》2023,23(11):2300091
Counterfeited biomedical products result in significant economic losses and pose a public health hazard for over a million people yearly. Hydrogels, a class of biomedical products, are being investigated as alternatives to conventional biomedical products and are equally susceptible to counterfeiting. Here, a biocompatible, physically unclonable function (BPUF) to verify the authenticity of therapeutically relevant hydrogels are developed. The principle of BPUF relies on the self-assembly of tyrosine into fibril-like structures which are incorporated into therapeutically relevant hydrogels resulting in their random dispersion. This unclonable arrangement leads to distinctive optical micrographs captured using an optical microscope. These optical micrographs are transformed into a unique security code through cryptographic techniques which are then used to authenticate the hydrogel. The temporal stability of the BPUFs are demonstrated and additionally, exploit the dissolution propensity of the structures upon exposure to an adulterant to identify the tampering of the hydrogel. Finally, a platform to demonstrate the translational potential of this technology in validating and detecting tampering of therapeutically relevant hydrogels is developed. The potential of BPUFs to combat hydrogel counterfeiting is exemplified by its simplicity in production, ease of use, biocompatibility, and cost-effectiveness. 相似文献
742.
Y. Marchal 《Journal of Molecular Structure》2008,880(1-3):38
The ubiquity of the hydrogen bond in many various scientific domains comes for a great part from its fundamental geometrical, thermodynamical and dynamical properties, but also owes much to the existence of such an exceptional molecule as the water molecule H2O. Illustrative examples of up to date problems that are picked in various different scientific fields that extend from physics to biology and strongly involve H-bonds and/or the water molecule are examined. They hopefully show that if science is to propose solutions to newly arising problems humanity has to face, it absolutely needs knowing more about the subtle properties of hydrogen bonds and the often ignored crucial roles of water molecules. The interest of teaching more than is up to now done hydrogen bonds in university courses of physics, chemistry or molecular biology is stressed as a conclusion. 相似文献
743.
Sphingomyelin (SM) is an important lipid of eukaryotic cellular membranes and neuronal tissues. We studied lateral diffusion in macroscopically oriented bilayers of synthetic palmitoylsphingomyelin (PSM) and natural sphingomyelins of egg yolk (eSM), bovine brain (bSM) and bovine milk (mSM) by pulsed field gradient NMR (PFG NMR) in the temperature range 45-60 °C. We found that the mean values of lateral diffusion coefficients (LDCs) of SMs are 1.9-fold lower compared with those of dipalmitoylphosphatidylcholine (DPPC), which is similar in molecular structure. This discrepancy could be explained by the characteristics of intermolecular SM interactions. The LDCs of different SMs differ: egg SM is most similar to PSM; both of them have a 10% higher LDC value compared with the other two natural SMs. Besides, all natural SMs show a complicated form of the spin-echo diffusion decay (DD), which is an indicator of a distribution of LDC values in bilayers. This peculiarity is explained by the broad distributions of hydrocarbon chain lengths of the natural SMs studied here, especially mSM and bSM. We confirmed the relationship between chain length and LDC in the bilayers by computer analysis of a set of (1)H NMR spectra obtained by scanning the value of the pulsed field gradient. There is a correlation between lower LDC values and SM molecules with longer acyl chains. The most probable mechanisms by which long-chain SM molecules decrease their lateral diffusion relative to the average value are protrusion into the other side of the bilayer or lateral separation into areas that diverge with their LDCs. 相似文献
744.
The physical parameters obtained from modal tests do not satisfy the dynamic constraints of eigenvalue function and orthogonality requirements due to modeling and measurement errors. The purpose of this study is to present the analytical equations on the updated stiffness and mass matrices in the satisfaction of such dynamic constraints. Minimizing the cost functions of the difference between analytical and desired physical parameter matrices, the corrected parameter matrices are straightforwardly derived by utilizing the Moore–Penrose inverse without using any multipliers. The cost functions given by a few researchers are utilized. From the comparison of the existing analytical results and the proposed equations, the validity of the proposed methods is evaluated in an application. 相似文献
745.
Summary: In this article we analyze in how far semiflexible behavior enhances the differences in the properties of classes of polymers whose topological structure varies. We focus on three pairs of macromolecular classes: stars vs. chains, unknotted rings vs. rings with one knot (trefoils), and stars vs. unknotted rings. For this we determine the mean-square radii of gyration and the bond-bond correlation functions through Monte Carlo simulations which use the bond fluctuation model. We show that introducing semiflexibility magnifies the differences between experimentally measurable quantities and may even lead to qualitative changes. Our simulation results are supported by theoretical studies which make use of the maximum entropy principle. 相似文献
746.
747.
748.
Francesco Ferdinando Summa Guglielmo Monaco Riccardo Zanasi Stefano Pelloni Paolo Lazzeretti 《Molecules (Basel, Switzerland)》2021,26(14)
The electric dipole–magnetic dipole polarizability tensor , introduced to interpret the optical activity of chiral molecules, has been expressed in terms of a series of density functions , which can be integrated all over the three-dimensional space to evaluate components and trace . A computational approach to , based on frequency-dependent electronic current densities induced by monochromatic light shining on a probe molecule, has been developed. The dependence of on the origin of the coordinate system has been investigated in connection with the corresponding change of . It is shown that only the trace of the density function defined via dynamic current density evaluated using the continuous translation of the origin of the coordinate system is invariant of the origin. Accordingly, this function is recommended as a tool that is quite useful for determining the molecular domains that determine optical activity to a major extent. A series of computations on the hydrogen peroxide molecule, for a number of different HO–OH dihedral angles, is shown to provide a pictorial documentation of the proposed method. 相似文献
749.
4-Hexyl-4′-[2-(4-isothiocyanatophenyl)ethyl]-1-1′-biphenyl, a liquid crystalline material shows smectic-B (SmB) and nematic phases, respectively, between 60.3–98.5°C and 98.5–130.8°C. X-ray diffraction patterns were recorded at different temperatures in the SmB phase and were used to compute translational order parameters. For this purpose, we have employed a theoretical model recently reported by Kapernaum and Giesselmann. The results obtained are discussed in terms of the basic understanding of the SmB phase. 相似文献
750.
Fusheng Wang Shihui Huo Shengjun Qiao Junran Zhang Zhufeng Yue 《Mathematical and Computer Modelling of Dynamical Systems: Methods, Tools and Applications in Engineering and Related Sciences》2013,19(1):58-76
Static aeroelastic and flutter characteristics of an aircraft composite wing with high aspect ratio were analysed by an effective Computational Fluid Dynamics and Computational Structure Dynamics coupled method. Effects of stiffness distribution on aeroelastic characteristics were considered. Honeycomb core sandwich composite was considered to be equivalent to an orthotropic material by stiffness and inertance equivalent method to allow highly efficient numerical simulation, which was used for analysis of bending and torsional stiffness distribution. The results showed that the redistributed aerodynamic load leads to a decrease of pressure difference between the upper and lower airfoils. The flutter speed of the composite wing is near 0.64 Ma. Both bending and torsional stiffness increases with a small increase of beam size. Stiffness of the wing root has a major influence generally on the static aeroelastic characteristics. Both the lift coefficient and the loss percent decrease with a small increase of beam size. Effects of stiffness distribution on frequency are not obvious. Flutter speed remains close to the initial value when the beam size is changed. 相似文献