35 research outputs found
Density functional theory studies on IR spectra of the triphenylene derivatives : a scaled quantum mechanical force field approach
Density functional theory, B3-LYP with the 6-31G* basis set was applied to study the structures and vibrational infrared spectra of triphenylene and the hexasubstituted triphenylene derivatives. The calculated force fields
were scaled using the scaled quantum mechanical force field method. The predicted vibrational frequencies were compared with the experimental IR spectra (500-4000 cm -1 ). The spectra were interpreted and vibrational assignments were reported. This study shows that the scaled density functional force field approach enables, through the transferability of scale factors, good interpretation of vibrational spectra of large molecules
Experimental and theoretical spectroscopic studies on selected igepals
Several nonionic igepals characterized by the formula (CmH2m+1 )-C6H4-(OCH2CH2 ) n OH were investigated by high resolution NMR and IR spectroscopy. Gauge invariant atomic orbital density functional theory NMR
calculations on model molecules in the gas phase additionally supported the assignment of experimental carbon signals. Different orientations of individual sub-units of an aliphatic chain relative to external magnetic field
and trans-gαuche transitions were assumed to explain complex patterns of carbon spectra in the aliphatic region of igepals with linear alkyl chain
Quantum effects in electrical conductivity and photoconductivity of single SbSI nanowire
For the first time current quantization is reported for antimony sulfoiodide (SbSI) nanowires. It has been
registered in current responses on electric eld switching as well as on illumination on and o . Current steps
determined in all experiments have been equal to each other within the experimental error. It has been explained
by the quantized change of free carrier concentration in nanowire. Lateral dimensions of SbSI nanowires estimated from quantum steps are comparable with geometrical data reported for the same technology of material preparation
Physicochemical analysis of sediments formed on the surface of hydrophilic intraocular lens after Descemet’s stripping endothelial keratoplasty
An intraocular lens (IOL) is a synthetic, artificial lens placed inside the eye that replaces
a natural lens that is surgically removed, usually as part of cataract surgery. The opacification of
the artificial lens can be related to the formation of the sediments on its surface and could seriously
impair vision. The physicochemical analysis was performed on an explanted hydrophilic IOL and
compared to the unused one, considered as a reference IOL. The studies were carried out using surface
sensitive techniques, which can contribute to a better understanding of the sedimentation process
on hydrophilic IOLs’ surfaces. The microscopic studies allowed us to determine the morphology of
sediments observed on explanted IOL. The photoelectron spectroscopy measurements revealed the
presence of organic and inorganic compounds at the lens surface. Mass spectroscopy measurements
confirmed the chemical composition of deposits and allowed for chemical imaging of the IOL
surface. Applied techniques allowed to obtain a new set of information approximating the origin
of the sediments’ formation on the surface of the hydrophilic IOLs after Descemet’s stripping
endothelial keratoplasty
Evolution of glassy carbon under heat treatment : correlation structure-mechanical properties
In order to accommodate an increasing demand for glassy carbon products with tailored characteristics, one has to understand the origin of their structure-related properties. In this work, through the use of high-resolution transmission electron microscopy, Raman spectroscopy, and electron energy loss spectroscopy it has been demonstrated that the structure of glassy carbon at different stages of the carbonization process resembles the curvature observed in fragments of nanotubes, fullerenes, or nanoonions. The measured nanoindentation hardness and reduced Young’s modulus change as a function of the pyrolysis temperature from the range of 600–2500 °C and reach maximum values for carbon pyrolyzed at around 1000 °C. Essentially, the highest values of the mechanical parameters for glassy carbon manufactured at that temperature can be related to the greatest amount of non-planar sp2-hybridized carbon atoms involved in the formation of curved graphene-like layers. Such complex labyrinth- like structure with sp2-type bonding would be rigid and hard to break that explains the glassy carbon high strength and hardness
The use of ZrO2 waste for the electrolytic production of composite Ni- P-ZrO2 powder
Ni–P–ZrO2 composite powder was obtained from a galvanic nickel bath with ZrO2 powder.
Production was conducted under galvanostatic conditions. The Ni–P–ZrO2 composite powder was
characterized by the presence of ZrO2 particles covered with electrolytical nanocrystalline Ni–P
coating. The chemical composition (XRF method), phase structure (XRD method) and morphology
(SEM) of Ni–P–ZrO2 and the distribution of elements in the powder were all investigated. Based
on the analyses, it was found that the obtained powder contained about 50 weight % Zr and
40 weight % Ni. Phase structure analysis showed that the basic crystalline component of the tested
powder is a mixed oxide of zirconium and yttrium Zr0.92Y0.08O1.96. In addition, the sample contains
very large amounts of amorphous compounds (Ni–P). The mechanism to produce the composite
powder particles is explained on the basis of Ni2+ ions adsorption process on the metal oxide
particles. Current flow through the cell forces the movement of particles in the bath. Oxide grains
with adsorbed nickel ions were transported to the cathode surface. Ni2+ ions were discharged.
The oxide particles were covered with a Ni–P layer and the heavy composite grains of Ni–P–ZrO2
flowed down to the bottom of the cell
Molecular structure, in vitro anticancer study and molecular docking of new phosphate derivatives of betulin
A series of 30-diethylphosphate derivatives of betulin were synthesized and evaluated
for their in vitro cytotoxic activity against human cancer cell lines, such as amelanotic melanoma
(C-32), glioblastoma (SNB-19), and two lines of breast cancer (T47D, MDA-MB-231). The molecular
structure and activities of the new compounds were also compared with their 29-phosphonate
analogs. Compounds 7a and 7b showed the highest activity against C-32 and SNB-19 cell lines. The
IC50 values for 7a were 2.15 and 0.91 M, and, for 7b, they were 0.76 and 0.8 M for the C-32 and
SNB-19 lines, respectively. The most potent compounds, 7a and 7b, were tested for their effects
on markers of apoptosis, such as H3, TP53, BAX, and BCL-2. For the whole series of phosphate
derivatives, a lipophilicity study was performed, and the ADME parameters were calculated. The
most active products were docked to the active site of the EGFR protein. The relative binding affinity
of selected phosphate betulin derivatives toward EGFR was compared with standard erlotinib on the
basis of ChemScore and KDEEP score. Positively, all derivatives docked inside the cavity and showed
significant interactions. Moreover, a molecular dynamics study also reveals that ligands 7a,b form
stable complexes and the plateau phase started after 7 ns
Correlation between locally ordered (hydrogen-bonded) nanodomains and puzzling dynamics of polymethysiloxane derivative
We examined the behavior of poly(mercaptopropyl)methylsiloxane
(PMMS), characterized by a polymer chain backbone of alternate
silicon and oxygen atoms substituted by a polar pendant group able to form
hydrogen bonds (−SH moiety), by means of infrared (FTIR) and dielectric
(BDS) spectroscopy, differential scanning calorimetry (DSC), X-ray diffraction
(XRD), and rheology. We observed that the examined PMMS forms relatively
efficient hydrogen bonds leading to the association of chains in the form of
ordered lamellar-like hydrogen-bonded nanodomains. Moreover, the recorded
mechanical and dielectric spectra revealed the presence of two relaxation
processes. A direct comparison of collected data and relaxation times extracted
from two experimental techniques, BDS and rheology, indicates that they
monitor different types of the mobility of PMMS macromolecules. Our
mechanical measurements revealed the presence of Rouse modes connected to
the chain dynamics (slow process) and segmental relaxation (a faster process),
whereas in the dielectric loss spectra we observed two relaxation processes related most likely to either the association−dissociation
phenomenon within lamellar-like self-assemblies or the sub-Rouse mode (α′-slower process) and segmental (α-faster process)
dynamics. Data presented herein allow a better understanding of the peculiar dynamical properties of polysiloxanes and associating
polymers having strongly polar pendant moieties
Aromaticity Effect on Supramolecular Aggregation. Aromatic vs. Cyclic Monohydroxy Alcohols
In this paper, the steric hindrance effect related to the presence of either an aromatic or cyclic
ring on the self-association process in the series of monohydroxy alcohols (MAs), from
cyclohexanemethanol to 4-cyclohexyl-1-butanol and from benzyl alcohol to 4-phenyl-1-
butanol, was studied using X-Ray Diffraction (XRD), Differential Scanning Calorimetry
(DSC), Fourier Transform Infrared (FTIR) spectroscopy, Broadband Dielectric Spectroscopy
(BDS) and the Pendant Drop (PD) methods. Based on FTIR results, it was shown that phenyl
alcohol (PhA) and cyclohexyl alcohol (CA) derivatives reveal substantial differences in the
association degree, the activation energy of dissociation, and the homogeneous distribution of
supramolecular nanoassociates suggesting that the phenyl ring exerts a stronger steric impact
on the self-assembling of molecules than cyclohexyl one. Additionally, XRD data revealed
that phenyl moiety introduces more heterogeneity in the organization of molecules compared
to the cyclic one. The changes in the self-association process of alcohols were also reflected
in differences in the molecular dynamics of the H-bonded aggregates, as well as in the
Kirkwood factor, defining the long-range correlation between dipoles, which were slightly
higher for CAs with respect to those determined for PhAs. Unexpectedly it was also found
that the surface layers of PhAs were more organized than those formed by CAs. Thus, these
findings provided insight into the impact of aromaticity on the self–assembly process, Hbonding
pattern, supramolecular structure, and intermolecular dynamics of the studied
alcohols