RESUMEN

This study aimed to investigate the effects of acid or alkali modification of isolated cassava starch (ICS) on its physicochemical properties. Acetic acid concentrations of 5%, 10%, and 20% v/v (0.87, 1.73, and 3.46 M, respectively) and calcium hydroxide concentrations of 0.15%, 0.20%, and 0.30% w/w (0.02, 0.025, and 0.04 M, respectively) were tested independently and compared with untreated isolated starch. The scanning electron microscope (SEM) shows starches with polyhedral and semispherical shapes; these modifications do not change the surface of the starch granules. Nanocrystals with orthorhombic crystal structure were extracted from ICS. Transmission electron microscopy (TEM) shows crystallites with a size (two-dimensional) of 20 ± 5 nm in length and 10 ± 2 nm in width and reveals that this starch contains nanocrystals with orthorhombic crystal structure. The X-ray patterns show that these nanocrystals are unaffected by acidic or alkaline treatments. The Ca+2 and CH3COO- ions do not interact with these nanocrystals. The alkaline treatment only affects the gelatinization temperature at a Ca(OH)2 concentration of 0.30%. Low concentrations of acidic and alkaline treatments affect the ability of cassava starch to absorb water and reduce the peak and final viscosity. The infrared spectra show that the modifications lead to C-H and C═C bond formations. ICS-B 0.30 can modify the amorphous regions of the starch, and the acid treatment leads to acetylation, which was confirmed by the presence of an IR band at 1740 cm-1.

RESUMEN

The 1-acyl thiourea family [R1C(O)NHC(S)NR2R3] exhibits the flexibility to incorporate a wide variety of substituents into their structure. The structural attributes of these compounds are intricately tied to the type and extent of substitution. In the case of 3-mono-substituted thioureas (R2 = H), the conformational behavior is predominantly shaped by the presence of an intramolecular N-H···O=C hydrogen bond. This study delves into the structural consequences stemming from the inclusion of substituents possessing hydrogen-donor capabilities within four novel 1-acyl-3-mono-substituted thiourea derivatives. A comprehensive suite of analytical techniques, encompassing FTIR, Raman spectroscopy, multinuclear (1H and 13C) NMR spectroscopy, single-crystal X-ray diffraction, and supported by computational methods, notably NBO (Natural Bond Orbital) population analysis, Hirshfeld analysis, and QTAIM (Quantum Theory of Atoms in Molecules), was harnessed to scrutinize and characterize these compounds. In the crystalline state, these compounds exhibit an intricate interplay of intermolecular interactions, prominently featuring an expansive network of hydrogen bonds between the hydroxy (-OH) groups and the carbonyl and thiocarbonyl bonds within the 1-acyl thiourea fragment. Notably, the topological analysis underscores significant distinctions in the properties of the acyl thiourea fragment and the intramolecular >C=O···H-N bond when transitioning from the isolated molecule to the crystalline environment.

RESUMEN

This study aims to investigate the impact of the π â†’ π* excitation localised in one monomer on the equilibrium geometry and oscillations of the AA dimer. Several low-frequency vibrations appear in pairs in the LIF spectrum because oscillations involving intermolecular hydrogen bonds are coupled, generating approximately symmetric and antisymmetric combinations (especially the COOH rocking modes, LIF: 295 and 301 cm-1). Furthermore, quantitative evaluation based on the TDDFT(B3LYP) results indicates that a dozen among 90 intramolecular oscillations are strongly coupled. In contrast, most vibrations are decoupled or weakly coupled, since they involve remote parts of the monomers. This makes several single vibrations active in the LIF spectrum (including the bending mode of the NH···O intramolecular hydrogen bond associated the strongest vibronic band 442 cm-1), while the other in each pair remains inactive. The reason for decoupling of oscillations and symmetry breaking is that the π â†’ π* electronic excitation is entirely localised within one of the monomers, which makes them no longer equivalent in terms of geometry and dynamics. Additionally, the excitation of one monomer induces strengthening and shortening by 6 pm of only one intermolecular hydrogen bond linking the carboxylic groups of both molecules. This causes the 1.7° in-plane distortion of the dimer and lowering of its symmetry to Cs group (from C2h for the S0 state). The distortion induces the activity of two low-frequency in-plane intermolecular vibrations, i.e. the geared oscillation (LIF: 58 cm-1) and the shearing motion (99 cm-1) of the monomers.

RESUMEN

Vibrational circular dichroism (VCD) spectra of chiral high-spin organic radicals are expected to show a strong intensity enhancement and are thought to be difficult to predict using state-of-the-art theoretical methods. Herein we show that the chiral triplet nitrene obtained from photochemical cleavage of N2 from enantiopure 2-azido-9H-fluorenol does not feature extraordinarily strong intensities and that the experimental spectra match nicely with calculated ones. Thereby, this study demonstrates the general feasibility of studies on chiral high-spin organics by matrix-isolation VCD.

RESUMEN

In this study, the FT-IR, FT-Raman, and UV-Vis spectroscopic properties of three monosubstituted phenylboronic acid derivatives: ortho-chlorophenylboronic acid (o-ClPhBA), meta-chlorophenylboronic acid (m-ClPhBA) and para-chlorophenylboronic acid (p-ClPhBA) molecules are investigated both experimentally and theoretically using Density Functional Theory (B3LYP) and Hartree Fock (HF). In order to find the stable possible conformations of the compounds, the conformational analysis was carried out by running potential energy surface (PES) scan by means of rotation of two structural parameters, the dihedral angles indicated as φ2 (C6-B-O1-H1A) and φ3 (C6-B-O2-H2A), varying from -180° to 180° with an increment of 10° using B3LYP/6-31G level of theory. Also, to determinate the most stable conformer for all the molecules, potential energy curve (PEC) the stable possible conformations on PES scan were investigated as a function of φ1 (C1-C6-B-O1) dihedral angle from 0° up to 180° with an increment of 10° using B3LYP/6-311++G(d,p) and HF/6-311++G(d,p) level of theory. For all the studied compounds, two conformational structures (conformer anti-anti, syn-syn) that did not have imaginary frequency values outside the equilibrium state (conformer anti-syn) were detected theoretically at the both methods. Due to their conformational flexibility, the relative stabilities of the anti-syn, anti-anti, and syn-syn conformers of o-ClPhBA, m-ClPhBA, and p-ClPhBA are 0.0, 4.66, and 6.76 kcal/mol, respectively, at the B3LYP/6-311++G(d,p) level of theory. For the HF/6-311++G(d,p) level of theory, the relative stabilities are 0.00, 4.54, and 6.11 kcal/mol for o-ClPhBA; 0.00, 3.98, and 1.51 kcal/mol for m-ClPhBA; and 0.00, 4.10, and 1.44 kcal/mol for p-ClPhBA, respectively. Some of the determined stable conformations of these molecules are different in symmetry groups. It was observed that the increase in the symmetry was effective in the of molecular properties, especially for vibrational frequencies. The structural parameter, dipole moments (µ), vibrational frequencies, polarizability (α), hyperpolarizability (ß), the highest occupied molecular orbital (HOMO), and the lowest unoccupied molecular orbital (LUMO) of the stable conformers were calculated by using Ab initio HF/6-311++G(d,p) and DFT/B3LYP/6-311++G(d,p) level of theory. The assignments of fundamental vibrational modes of the studied molecule were performed based on total energy distribution (TED) analysis.

RESUMEN

This dataset provides a comprehensive collection of vibrational data for the purpose of structural health monitoring, particularly focusing on the detection of bolt loosening in offshore wind turbine jacket foundations. The data set comprises 780 comma-separated values (CSV) files, each corresponding to specific experimental conditions, including various structural states of the wind turbine's support structure. These states are systematically varied considering three main aspects: the amplitude of a white noise (WN) signal, the type of bolt damage, and the level at which damage has occurred. The data were meticulously collected using eight triaxial accelerometers (PCB R Piezotronic model 356A17), strategically placed at different locations on a scaled-down replica of an offshore jacket-type wind turbine. This setup facilitated the acquisition of detailed vibrational data through a National Instruments' data acquisition (DAQ) system, comprising six input modules (NI 9234 model) housed in a chassis (cDAQ model). The white noise signal, simulating wind disturbance at the nacelle, was produced by a modal shaker and varied in three amplitudes (0.5, 1, and 2), directly proportional to the induced vibration in the wind turbine. The dataset uniquely captures the vibrational behaviour under different scenarios of bolt loosening in the turbine's foundation. The conditions include a healthy state (bolts tightened to 12 Nm) and various degrees of loosening (bolts loosened to 9 Nm, 6 Nm, and completely absent), examined at four distinct levels of the turbine's base structure. This granular approach offers a nuanced view of how varying degrees of bolt loosening impact the vibrational characteristics of the structure. The value of this dataset lies in its potential for wide-ranging applications in the field of structural health monitoring. Researchers and engineers can leverage this data for developing and testing new methodologies for early damage detection and progressive damage assessment in offshore wind turbines. The dataset's comprehensive coverage of damage scenarios makes it a valuable resource for the validation and enhancement of existing damage detection algorithms. Furthermore, the dataset can serve as a benchmark for comparing the efficacy of different vibrational analysis techniques in the context of wind turbine maintenance and safety. Its application is not only limited to wind turbines but can extend to other structures where bolt integrity is critical for operational safety. This dataset represents a significant contribution to the field of structural health monitoring, providing a detailed and practical resource for enhancing the reliability and safety of offshore wind turbines and similar structures.

RESUMEN

1,2,3-triazole skeleton is a valuable building block for the discovery of new promising anticancer agents. In the present work, the molecular structure of the synthesized anticancer drug 2-(4-chlorophenyl)-5-(pyrrolidin-1-yl)-2H-1,2,3-triazole-4-carboxylic acid (1b) and its anionic form (2b) was characterized by means of the B3LYP, M06-2X and MP2 quantum chemical methods, optimizing their monomer, cyclic dimer and stacking forms using the Gaussian16 program package. The molecular structure was found to be slightly out of plane. The good agreement between the IR and Raman bands experimentally observed in the solid state with those calculated theoretically confirms the synthesized structures. All of the bands were accurately assigned according to functional calculations (DFT) in the monomer and dimer forms, together with the polynomic scaling equation procedure (PSE). Therefore, the effect of the substituents on the triazole ring and the effect of the chlorine atom on the molecular structure and on the vibrational spectra were evaluated through comparison with its non-substituted form. Through molecular docking calculations, it was evaluated as to how molecule 1b interacts with few amino acids of the MMP-2 metalloproteinase receptor, using Sybyl-X 2.0 software. Thus, the relevance of triazole scaffolds in established hydrogen bond-type interactions was demonstrated.

RESUMEN

The 1,2,3-triazole derivative 2-(4-chlorophenyl)-5-(pyrrolidin-1-yl)-2H-1,2,3-triazole-4-carboxylic acid with potential anticancer activity was used as a ligand in complex formation with the lanthanum(III) ion. The molecular structure and vibrational spectra of the complex were optimized at three DFT levels, and the scaled IR and Raman spectra were compared to the experimental ones. Several scaling procedures were used. Through a detailed analysis, the structure predicted for the newly synthetized La(III) complex was confirmed by the good accordance of the calculated/experimental IR and Raman spectra. The best DFT method appeared to be M06-2X with the Lanl2mb basis set, followed closely by Lanl2dz. The effect of the lanthanide atom on the molecular structure and atomic charge distribution of the triazole ring was evaluated. The potential free radical scavenging activity of both the ligand and the complex was investigated in several radical-generating model systems. The potential mechanisms of antioxidant action (hydrogen atom transfer (HAT) and single-electron transfer (SET)) were elucidated.

RESUMEN

The molecular structure and vibrational spectra of six 1,2,3-triazoles-containing molecules with possible anticancer activity were investigated. For two of them, the optimized geometry was determined in the monomer, cyclic dimer and stacking forms using the B3LYP, M06-2X and MP2 methods implemented in the GAUSSIAN-16 program package. The effect of the para-substitution on the aryl ring was evaluated based on changes in the molecular structure and atomic charge distribution of the triazole ring. An increment in the positive N4 charge was linearly related to a decrease in both the aryl ring and the carboxylic group rotation, with respect to the triazole ring, and by contrast, to an increment in the pyrrolidine ring rotation. Anionic formation had a larger effect on the triazole ring structure than the electronic nature of the different substituents on the aryl ring. Several relationships were obtained that could facilitate the selection of substituents on the triazole ring for their further synthesis. The observed IR and Raman bands in the solid state of two of these compounds were accurately assigned according to monomer and dimer form calculations, together with the polynomic scaling equation procedure (PSE). The large red-shift of the C=O stretching mode indicates that strong H-bonds in the dimer form appear in the solid state through this group.

Asunto(s)

RESUMEN

A comprehensive analysis of the intermolecular interaction energy and anharmonic vibrations of 41 structures of the HXeY⋯HX (X, Y = F, Cl, Br, I) family of noble-gas-compound complexes for all possible combinations of Y and X was conducted. New structures were identified, and their interaction energies were studied by means of symmetry-adapted perturbation theory, up to second-order corrections: this provided insight into the physical nature of the interaction in the complexes. The energy components were discussed, in connection to anharmonic frequency analysis. The results show that the induction and dispersion corrections were the main driving forces of the interaction, and that their relative contributions correlated with the complexation effects seen in the vibrational stretching modes of Xe-H and H-X. Reasonably clear patterns of interaction were found for different structures. Our findings corroborate previous findings with better methods, and provide new data. These results suggest that the entire group of the studied complexes can be labelled as "naturally blueshifting", except for the complexes with HI.

RESUMEN

Different structures of free base (FB), two cationic forms (CA) and three hydrochloride forms (HCl) of cholinesterase inhibitor tacrine used for treatment of Alzheimer 's disease was evaluated using hybrid B3LYP calculations in order to perform their complete vibrational assignments using the scaled harmonic force fields. Structures of anhydrous form of tacrine have been optimized in gas phase and in aqueous solution. The structure of form III HCl is in agreement with the experimental determined by X-ray diffraction while the predicted IR, Raman, 1H- 13C NMR and UV spectra show good correlations with the corresponding experimental ones. Energy values show that the three forms of HCl can exist in both media because these energetic values decrease from 35.15 kJ/mol in gas phase to 5.51 kJ/mol in solution. For the most stable species of tacrine, the following stability order using natural bond orbital (NBO) studies was found: form I HCl > form III HCl > form I CA > FB. CA presents the higher solvation energy value, as reported for hydrochloride species of alkaloids and antihypertensive agents. The structural parameters of form III of HCl present better concordance and corresponds to that experimental observed in the solid phase. Higher topological properties of form III together with the strong N2-H26⋯Cl31 interaction could justify the presence of this form in the solid phase and in solution and the higher stabilities in both media. The gap values support the higher reactivity of form III while FB is the less reactive species in both media. Complete vibrational assignments for FB, CA and HCl species together with the corresponding scaled force constants are reported.

RESUMEN

BACKGROUND: The left ventricular assist device (LVAD) is a mechanical circulatory support device for patients with severe heart failure. Microbubbles caused by cavitation in the LVAD can potentially lead to physiological and pump-related complications. The aim of this study is to characterize the vibrational patterns in the LVAD during cavitation. METHODS: The LVAD was integrated into an in vitro circuit and mounted with a high-frequency accelerometer. Accelerometry signals were acquired with different relative pump inlet pressures ranging from baseline (+20 mmHg) to -600 mmHg in order to induce cavitation. Microbubbles were monitored with dedicated sensors at the pump inlet and outlet to quantify the degree of cavitation. Acceleration signals were analyzed in the frequency domain to identify changes in the frequency patterns when cavitation occurred. RESULTS: Significant cavitation occurred at the low inlet pressure (-600 mmHg) and was detected in the frequency range between 1800 and 9000 Hz. Minor degrees of cavitation at higher inlet pressures (-300 to -500 mmHg) were detected in the frequency range between 500-700, 1600-1700 Hz, and around 12 000 Hz. The signal power of the dominating frequency ranges was statistically significantly different from baseline signals. CONCLUSION: Vibrational measurements in the LVAD can be used to detect cavitation. A significant degree of cavitation could be detected in a wide frequency range, while minor cavitation activity could only be detected in more narrow frequency ranges. Continuous vibrational LVAD monitoring can potentially be used to detect cavitation and minimize the damaging effect associated with cavitation.

Asunto(s)

RESUMEN

Base pairs of 4-amino-3-nitrobenzonitrile (4A-3NBN) molecule with uracil, thymine and cytosine nucleobases were optimized and compared to natural Watson-Crick (WC) pairs. The slightly greater flexibility of the -NO2 group of 4A-3NBN than the N3-H group of the natural nucleobases together with a noticeable higher dipole moment of its pairs can facilitate disruption of the DNA/RNA helix formation. Several new mutagenic modified nucleosides with 4A-3NBN and 3-amino-2-nitrobenzonitrile (3A-2NBN) were proposed as antiviral prodrugs and their base pairs optimized. The special characteristics of these prodrugs appear appropriated for their clinical use. The counterpoise (CP) corrected interaction energies of the base pairs were calculated and compared to the natural ones. The M06-2X DFT method was used for this purpose. The molecular structure of 4A-3NBN was analyzed in detail and the crystal unit cell was simulated by a tetramer form and eight dimer forms. The performance of the B3LYP, X3LYP and M06-2X methods was tested on the vibrational wavenumbers in the monomer, dimer and tetramer forms of 4A-3NBN. The observed IR and Raman bands were assigned according to the optimum dimer II form determined by B3LYP and by the tetramer form calculated by M06-2X, which is the expected unit cell that forms the crystal net. The two best scaling procedures were used.Communicated by Ramaswamy H. Sarma.

Asunto(s)

RESUMEN

Hydrogen bonding is one of the most important inter-molecular interactions in the field of biochemistry and medicinal chemistry. Such non-covalent interactions play a vital role in self-assembly phenomena, chemical structures, material properties and enzymatic catalysis. Herein, we present hydrogen bonding phenomenon in alcohols-dinitrobenzene (DNB) radical anion/dianion systems using electrochemical and computational approaches. First, 1,3-DNB radical anion and dianion were generated through electrochemical method and then hydrogen bonding interactions with aliphatic alcohols in DMSO are studied through cyclic voltammetry (CV). CV results show that the cathodic peak potential of 1,3-Dinitrobenzene in Dimethyl sulfoxide is shifted catholically upon addition of alcohols which represent hydrogen bonding phenomenon. Theoretical investigations are performed to gain deep insight on hydrogen bonding interaction strength in DNB-alcohol systems. H-bonding interaction of all isomers of DNB (1,2-, 1,3-, 1,4-), its corresponding radical anion, and dianion with aliphatic alcohols is studied using density functional calculations. The strength of H-bonding is evaluated both qualitatively and quantitatively using interaction energies, vibrational and electronic spectroscopic analysis. Understanding of these interactions will be helpful in gaining insight into biological systems where these interactions play significant role.

Asunto(s)

RESUMEN

Osseointegration implant has attracted significant attention as an alternative treatment for transfemoral amputees. It has been shown to improve patients' sitting and walking comfort and control of the artificial limb, compared to the conventional socket device. However, the patients treated with osseointegration implants require a long rehabilitation period to establish sufficient femur-implant connection, allowing the full body weight on the prosthesis stem. Hence, a robust assessment method on the osseointegration process is essential to shorten the rehabilitation period and identify the degree of osseointegration prior to the connection of an artificial limb. This paper investigates the capability of a vibration-related index (E-index) on detecting the degree of simulated osseointegration process with three lengths of the residual femur (152, 190 and 228 mm). The adhesive epoxy with a setting time of 5 min was applied at the femur-implant interface to represent the stiffness change during the osseointegration process. The cross-spectrum and colormap of the normalised magnitude demonstrated significant changes during the cure time, showing that application of these plots could improve the accuracy of the currently available diagnostic techniques. Furthermore, the E-index exhibited a clear trend with a noticeable average increase of 53% against the cure time for all three residual length conditions. These findings highlight that the E-index can be employed as a quantitative justification to assess the degree of osseointegration process without selecting and tracing the resonant frequency based on the geometry of the residual femur.

Asunto(s)

RESUMEN

In this research, a combined study on structures and vibrational spectra of antiviral rimantadine have been performed using hybrid B3LYP/6-311++G∗∗ calculations and the scaled quantum force field (SQMFF) procedure. Harmonic force fields and scaled force constants of Free Base (FB), Cationic (CA) and Hydrochloride (HCl) species derived from the antiviral rimantadine have been calculated in gas phase and in aqueous solution using normal internal coordinates and scaling factors. Good correlations were acquired comparing the theoretical IR, Raman, 1H- 13C-NMR and UV spectra of three species with the analogous experimental ones, suggesting probably, the presence of all them in both phases. The main force constants of three species have evidenced lower values than the corresponding to antiviral amantadine. The ionic character of N1-H33⋯Cl36 bond of HCl species in aqueous solution evidence positive Mulliken charge on N1 atom indicating that this species is as CA one. Rimantadine presents higher solvation energies in water than other antiviral species, such as chloroquin, niclosamide, cidofovir and brincidofovir. The FB and HCl species of rimantadine are slightly less reactive than the corresponding to amantadine while the opposite is observed for the CA species. The predicted ECD spectra for the FB and CA species show positive Cotton effect different from the negative observed for the HCl one. These different behaviours of three species of rimantadine could probably explain the differences observed in the intensities of bands predicted in the electronic spectra of these species.

RESUMEN

In this study, detailed structural and vibrational analysis of merocyanine has been investigated using Raman, surface enhanced Raman scattering (SERS) and surface-enhanced resonance Raman scattering (SERRS). The Raman, SERS and SERRS studies aided by density functional theoretical (DFT) calculations clearly established the prevalence of the trans- and cis-conformers of the protonated form of merocyanine (MCH+) in solid and acetonitrile solution. The binding characteristics of merocyanine adsorbed on nanostructured silver-coated films (SCFs) were investigated using excitation-dependent SERS, concentration-dependent SERRS and DFT studies. The conformers of merocyanine involved in the surface adsorption processes were recognized. The prominent marker bands observed at 1538 (ethylenic C=C stretch) and 1133 cm-1 (pyridinium C-N stretch) in the Raman spectrum of merocyanine in acetonitrile shifted to 1540 and 1126 cm-1, respectively on the nanostructured SCFs. The shift in the marker bands is associated with either the preferential binding of selective conformer or change in resonance equilibrium between the benzenoid and quinoid forms. The excitation wavelength dependent SERS spectrum infers that in addition to the major contribution from the electromagnetic enhancement, chemical (resonance) effect leads to the amplification of the 1540 cm-1 band. The concentration-dependent SERRS study showed maximum enhancement for the nanostructured SCFs functionalized with 1 µM concentration of merocyanine, indicative of monolayer coverage. For lower concentrations of merocyanine, the SERRS signal intensity reduced without any alteration in the peak positions. The SERRS study thus, revealed sub-nanomolar (0.1 nM) sensing of merocyanine using nanostructured SCFs with the analytical enhancement factor (AEF) of ∼ 1010 for the 1126 cm-1 and 1540 cm-1 Raman bands for MC concentration of 0.1 nM. In this study, combination of SERRS and DFT have clearly established the predominance of trans-MCH+ on the nanostructured silver surface with minor contribution from cis-MCH+, which remain exclusively bound to the surface via the phenoxyl ring O atom. This conformational surface selectivity of geometrical isomers of merocyanine using nanostructured surfaces can be further explored for energy efficient and economical separation of geometrical isomers.

RESUMEN

The positively charged products of Cisplatin hydrolysis can form bonds with Guanine and Adenine, showing the ability to crosslink with nucleobases within the double helical DNA, and leading to apoptosis of the neoplastic cell. It has been proved that the presence of chemicals other than nucleobases, compound of aromatic rings with a nitrogen lone pair on the ring, such as B vitamins, may have a competitive character in relation to a chemotherapeutic drug. A theoretical study confirms the stability of bonds formed not only between Cisplatin and Guanine/Adenine but also Cisplatin and B vitamins, namely Thiamine (vit.B1), Niacin (vit.B3), Riboflavin (vit.B2) and Pyridoxal phosphate (vit.B6). That is why it seems to be justified to conduct the research on the physicochemical, thermochemical and optical properties of mono and diaqua complexes of Cisplatin with nucleobases and B vitamins. Equally important is carrying out such research as spectroscopic measurements, bond order analysis and vibrational analysis of the studied complexes. The complexation reaction is spontaneous and thermodynamically favored with the high electronegativity value, a shift of the electron density from the metal zone towards organic compounds, a reduction the value of gap parameter and a shift of the maximum absorbance ΔλABS towards longer wavelengths. Moreover, the performed density variation upon photoexcitation showed the contributions from HOMO→LUMO transition, where the maximum of the absorption band shifts towards shorter wavelengths compared to the cisPt derivatives, thereby lowering the photoexcitation energy. The formation of complexes causes the reduction of energy gap (ΔEgap) values and show higher kinetic stability with high values of gap. The bonding energies between Cisplatin and the target molecules were performed. Cisplatin forms the strongest bonds with Guanine and Pyridoxal phosphate (vit.B6). The vibrations of Pt-N7 bond in complexes occur in the low range of frequencies with low intensities. Only in case of nucleobases appeared vibrations of Pt-N7 in high frequencies. The highest intensity is shown by symmetry and asymmetry stretching vibrations of H-O(H2O) bonds in the high range of frequencies. The vibrations related with ammonium groups (NH3) of great importance appear in the medium and high range of frequencies. The complexes with Guanine show the highest intensities. A theoretical IR spectra were studied. The obtained calculated IR spectra for native nucleobases and vitamins from B group were compared with their experimental FT-IR. So the conducted research provides theoretical knowledge in practical terms regarding the physicochemical and spectral properties of the formed Cisplatin complexes with both nucleobases and B vitamins. Theoretical and partially experimental studies of the molecular and electronic structure or prediction of spectroscopic characteristics are quite useful for better understanding of the reactivity of this drug with physiological target molecules.

Asunto(s)

RESUMEN

Osseointegrated prostheses are widely used following transfemoral amputation. However, this technique requires sufficient implant stability before and during the rehabilitation period to mitigate the risk of implant breakage and loosening. Hence, reliable assessment methods for the osseointegration process are essential to ensure initial and long-term implant stability. This paper researches the feasibility of a vibration analysis technique for the osseointegration (OI) process by investigating the change in the dynamic response of the residual femur with a novel implant design during a simulated OI process. The paper also proposes a concept of an energy index (the E-index), which is formulated based on the normalized magnitude. To illustrate the potential of the E-index, this paper reports on changes in the vibrational behaviors of a 133 mm long amputated artificial femur model and implant system, with epoxy adhesives applied at the interface to simulate the OI process. The results show a significant variation in the magnitude of the colormap against curing time. The study also shows that the E-index was sensitive to the interface stiffness change, especially during the early curing process. These findings highlight the feasibility of using the vibration analysis technique and the E-index to quantitatively monitor the osseointegration process for future improvement on the efficiency of human health monitoring and patient rehabilitation.

Asunto(s)

RESUMEN

Alkannin is the main coloring matter of Alkanet, a natural red dye extracted from the root of Alkanna tinctoria L. Shikonin, the optical isomer of alkannin, is extracted from Lithospermum erythrorhizon. As both red dyes are only slightly soluble in water, the application of ordinary Raman spectroscopy is limited. Thus, Surface-enhanced Raman spectroscopy (SERS) can be successfully applied to the study of the red dyes solutions. Solid alkannin and shikonin were characterized by ordinary Raman spectroscopy. Density Functional Theory (DFT) methods were used to calculate the Raman spectrum of the dyes and to assign the experimental Raman bands to their vibrational normal modes. Different pH conditions were tested in order to determine the optimal conditions for the SERS detection of alkannin and shikonin. Based on the previous results, a perpendicular orientation of the red dyes on the Ag substrate was deducted. Finally, shikonin was identify by SERS spectroscopy in a dyed paper sample from an 8th century handscroll from Japan.

Asunto(s)