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Wyszukujesz frazę "molecules" wg kryterium: Temat


Tytuł:
First-principles study on the adsorption structure of water molecules on a pyrite (100) surface
Autorzy:
Liu, Yingchao
Chen, Jianhua
Li, Yuqiong
Zhang, Junjie
Kang, Duan
Powiązania:
https://bibliotekanauki.pl/articles/1447970.pdf
Data publikacji:
2021
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
pyrite
water molecules
adsorption
Opis:
The hydration structure of water molecule adsorption at different coverages of a monolayer on a pyrite (100) surface were simulated using the density functional theory (DFT) method. The results demonstrate that the Fe-O interaction weakens and the adsorption energy per water molecule decreases with increasing water coverage, except at a monolayer coverage of 12/12 (i.e., full coverage). H-S and H-O hydrogen bonds were formed on the nearest surface layer. When large amounts of water molecules adsorb onto the surface, the adsorbed water molecules can be divided into three layers: the layer nearest to the surface, the second nearest to the surface, and the layer farthest from the surface. The thickness of the former two layers is approximately 5.5 Å. The three layers have water densities of 1.12 g/cm3, 1.08 g/cm3, and 0.95 g/cm3, respectively, suggesting that there is a strong interaction between the pyrite surface and water molecules and the influence of surface structure on water adsorption reaches a distance of more than 10 Å. Dynamics simulations suggest that the water molecules close to the mineral surfaces are in an orderly arrangement while those far from the surface are disordered.
Źródło:
Physicochemical Problems of Mineral Processing; 2021, 57, 2; 121-130
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Cell adhesion molecules and their possible role in the pathology of the peripheral nerves – a review of the literature
Autorzy:
Niezgoda, Adam
Powiązania:
https://bibliotekanauki.pl/articles/552657.pdf
Data publikacji:
2015
Wydawca:
Stowarzyszenie Przyjaciół Medycyny Rodzinnej i Lekarzy Rodzinnych
Tematy:
cell adhesion molecules
demyelination
polyneuropathies.
Źródło:
Family Medicine & Primary Care Review; 2015, 4; 323-326
1734-3402
Pojawia się w:
Family Medicine & Primary Care Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analitical criteria of homogeneous and heterogeneous detonation of liquid energetic materials
Autorzy:
Kaim, S.
Powiązania:
https://bibliotekanauki.pl/articles/92588.pdf
Data publikacji:
2013
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Przemysłu Organicznego
Tematy:
mechanism detonation initiation
hot spots
nanopores
emission atoms and molecules
shock dissociation molecules
Opis:
Statistical theory of liquids is used to investigate mechanism of detonation initiation on fronts of flat shock waves in homogeneous liquid and in liquid containing spherical nanopores. We calculated thermodynamic parameters of liquid methane sufficient for shock dissociation of molecules at a front of a shock wave. Calculations of the average single-particle force potential show that at high pressures and temperatures atoms and molecules get emitted from the surface into a nanopore with hyper-thermal speeds. Implosion of spherically symmetric stream of molecules may lead to destruction of the molecules at impact. We explained existence of top and bottom bounds for pressure during detonation initiation in heterogeneous energetic materials. In terms of pair interaction potentials and correlation functions there are formulated criteria for boundary values of thermodynamic parameters which are required for initiation of homogeneous and heterogeneous detonations based on the "hot spot"’ mechanism.
Źródło:
Materiały Wysokoenergetyczne; 2013, T. 5; 5-13
2083-0165
Pojawia się w:
Materiały Wysokoenergetyczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Dendrimers: properties and applications.
Autorzy:
Klajnert, Barbara
Bryszewska, Maria
Powiązania:
https://bibliotekanauki.pl/articles/1044187.pdf
Data publikacji:
2001
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
cascade molecules
dendrimers
PAMAM dendrimers
Opis:
Dendrimers are a new class of polymeric materials. They are highly branched, monodisperse macromolecules. The structure of these materials has a great impact on their physical and chemical properties. As a result of their unique behaviour dendrimers are suitable for a wide range of biomedical and industrial applications. The paper gives a concise review of dendrimers' physico-chemical properties and their possible use in various areas of research, technology and treatment.
Źródło:
Acta Biochimica Polonica; 2001, 48, 1; 199-208
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Selected small molecules as inducers of pluripotency
Autorzy:
Baranek, Małgorzata
Markiewicz, Wojciech
Barciszewski, Jan
Powiązania:
https://bibliotekanauki.pl/articles/1038727.pdf
Data publikacji:
2016
Wydawca:
Polskie Towarzystwo Biochemiczne
Tematy:
reprogramming
pluripotency
small molecules
iPSCs
Opis:
The general idea of regenerative medicine is to fix or replace tissues or organs with live and patient-specific implants. Pluripotent stem cells are capable of indefinite self-renewal and differentiation into all cell types of the body. An easily accessible source of induced pluripotent stem cells (iPSCs) may allow obtaining and culturing tissues in vitro. Many approaches in the methods leading to obtain iPSCs have been tested in order to limit immunogenicity and tumorigenesis, and to increase efficiency. One of the approaches causing pluripotency is usage of small molecule compounds. It would be of great importance to assess their specific properties and reveal their new capacity to induce pluripotent stem cells and to improve reprogramming efficiency. Identification of the epigenetic changes during cellular reprogramming will extend our understanding of stem cell biology and many therapeutic applications. In this paper we discuss mainly the nucleotide derivatives, already proven or for now only putative inducers of the cells' pluripotency, that modulate the epigenetic status of the cell.
Źródło:
Acta Biochimica Polonica; 2016, 63, 4; 709-716
0001-527X
Pojawia się w:
Acta Biochimica Polonica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Calcium phosphate nanoparticles for delivering synthetic drug molecules across the cell membrane
Autorzy:
Rotan, O.
Sokolova, V.
Schrader, T.
Epple, M.
Powiązania:
https://bibliotekanauki.pl/articles/285174.pdf
Data publikacji:
2014
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Polskie Towarzystwo Biominerałów
Tematy:
nanoparticles
cell membranes
drug molecules
Źródło:
Engineering of Biomaterials; 2014, 17, no. 128-129; 77-78
1429-7248
Pojawia się w:
Engineering of Biomaterials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Na-montmorillonite modified with ammonium salts and azobenzene as a photoactive nanomaterial
Autorzy:
Koteja, A.
Matusik, J.
Powiązania:
https://bibliotekanauki.pl/articles/184535.pdf
Data publikacji:
2016
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
inorganic solid structures
organic molecules
minerals
Opis:
Modification of inorganic solid structures (e.g. minerals) with organic molecules is a constantly developed topic in material sciences. The organic functionalization leads to the production of new materials with integrated properties of both the organic and inorganic component. In the presented study we have modified a Na-montmorillonite with alkylammonium surfactants and subsequently azobenzene, in order to obtain a nanomaterial that shows response to UV radiation. Azobenzene is a photoswitchable organic molecule capable to change its conformation upon UV radiation from the trans- to cis-azobenzene isomer. This reaction is coupled with a change of the molecules shape and dimensions (Klajn 2010). The montmorillonite is a layered aluminosilicate that serves as an excellent host structure for organic guest species. Due to the net negative layer charge it shows the ability to swell and to exchange the originally present interlayer cations. These properties allow the intercalation of bulk organic molecules and to control their arrangement. Much attention has been paid to the possibility of transferring the photoswitching ability of organic molecule into the motion of the whole organo-mineral structure (Heinz et al. 2008). Such nanoswitch is particularly appealing as it is controlled with radiation – remotely and at a precise location. The efficiency of a synthesized nanoswitch depends on an accurate selection of the host and guest component. The target of this study to test a series of organic surfactants and to establish a modification pathway that leads to obtaining a material most promising in the view of its photoresponsive behavior. The montmorillonite modification was performed in a two-step procedure, as the direct intercalation of a nonionic azobenzene is not possible. First, the Na-montmorillonite (denoted SWy) was ion-exchanged with trimethylalkylammonium cations abbreviated C n and benzyldimethylalkylammonium cations – BC n , where n refers to the number of carbon atoms in the alkyl chain and is equal to 12, 14 or 16. In the second step the organo-montmorillonites were reacted with azobenzene (AzBz) for 24 h at 120°C in a hermetically closed teflon vessel. The yellowish products were characterized with the X-Ray diffraction (XRD), the infrared spectroscopy (FTIR) and CHN elemental analysis. In all cases the intercalation of the ammonium cation caused an increase of the montmorillonites basal spacing ( d 001 ). The d 001 values were equal to 16.4 Å, 18.2 Å and 20.5 Å for SWy-C 12 , SWy-C 14 and SWy-C 16 , respectively. The samples modified with the BC n cations showed ~1.5 Å larger basal spacing, due to the presence of the benzyl group in the intercalated molecule. A linear relationship was observed between the d 001 value and the alkyl chain length of the introduced salts. This suggests that the organic cations formed paraffin-type aggregates in the interlayer (Ogawa et al. 1999) where the molecules are inclined to the layer surface. The FTIR spectra of modified SWy sample showed intense bands corresponding to CH 2 vibration modes. Along with the increasing alkyl chain length the CH 2 stretching bands shifted towards lower energies. This is an effect of growing packing density of alkylammonium molecules in the interlayer (He et al. 2004) and it is coupled with straightening of the alkyl chains due to transformation of disordered gauche conformer to the ordered all-trans conformer (Vaia et al. 1994). It can be concluded that the longer alkyl chains (C 16 and BC 16 ) form more ordered, solid-like aggregates in the interlayer space. The molar content of organic molecules was calculated basing on the CHN elemental analysis. The amount of intercalated alkylammonium cations was nearly equal to the cation exchange capacity (CEC) of montmorillonite – 88.9 meq/100 g. The reaction with azobenzene was most effective for montmorillonite modified with the alkylammonium cations having the longest chains as confirmed by the XRD patterns. The d 001 values of SWy-C 16 and SWy-BC 16 samples after reaction with AzBz increased to 36.9 Å and 35.9 Å, respecively. Well resolved and intense (001) peaks as well as the presence of the 2 nd and 3 rd order reflections indicated a highly ordered structure of these intercalates. On the contrary, diffraction peaks were less resolved and broadened for samples prepared with the shorter C 12 , C 14 , BC 12 and BC 14 molecules after reaction with AzBz. Based on these results, it is assumed that the long chain alkylammonium ions are more effective surfactants for the further intercalation of azobenzene into the montmorillonites interlayer space. The obtained highly ordered structures are promising materials for application as photo-actuated nanoswitches.
Źródło:
Geology, Geophysics and Environment; 2016, 42, 1; 87-88
2299-8004
2353-0790
Pojawia się w:
Geology, Geophysics and Environment
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Resonance contributions to low-energy electron collisions with molecular hydrogen
Autorzy:
Horácek, J.
Cížek, M.
Houfek, K.
Kolorenc, P.
Pichl, L.
Powiązania:
https://bibliotekanauki.pl/articles/148461.pdf
Data publikacji:
2003
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
electron scattering
molecules
attachment
vibrational excitation
Opis:
Calculations of electron dissociative attachment and vibrational excitation of molecular hydrogen by low-energy electrons based on an improved nonlocal resonance model are reported. The role of the rotational excitation of the target molecules is discussed.
Źródło:
Nukleonika; 2003, 48, 2; 109-112
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Evaluation of neutrophil phagocytic, complement functions, and cytokines expression among diabetic patients in Abuja, Nigeria
Autorzy:
Babandina, Musa Muhammad
Mainasara, Abdullahi Suleiman
Bakare, Mustapha
Emeribe, Anthony Uchenna
Shuwa, Halima Ali
Haruna, Shamsuddeen
Muhammad, Aminu Said
Abdullahi, Idris Nasir
Powiązania:
https://bibliotekanauki.pl/articles/454973.pdf
Data publikacji:
2019
Wydawca:
Uniwersytet Rzeszowski. Wydawnictwo Uniwersytetu Rzeszowskiego
Tematy:
diabetes mellitus
effector molecules
pro-inflammatory markers
Opis:
Introduction. Inflammatory response in Diabetes Mellitus (DM) begins with chronic sub-clinical inflammations as a result of insulin resistance and activation of both innate and adaptive immune system as the disease progresses to complicated diabetes. Hence, the present study investigated the neutrophil phagocytic, complement function (CH50), and some cytokine profiles among diabetic and non-diabetic patients attending the National Hospital in Abuja, Nigeria. Aim. To evaluate the neutrophil phagocytic, complement function (CH50), and some cytokine profiles among post-operative septic diabetic and post-operative septic non-diabetic patients at the National Hospital in Abuja, Nigeria. Material and methods. Subjects were recruited by convenient sampling technique through interviewer-administered questionnaires. Subsequently, blood samples were collected. Fasting blood sugar (FBS) (mmol/L) was determined using glucose oxidase method. Neutrophil function test (Fmol/phag) was assayed using nitroblue tetrazolium reduction test (NBT). Hemolytic complement function (CH 50) test was conducted using serum harvested from sheep sensitized with human group (ORh D +ve) red blood cells. While serum Interleukin-4, -6, -10 and TNF- α were determined using Enzyme Linked Immunosorbent Assay (ELISA). Results. Mean ± Standard deviation (SD) of FBS concentration of 10.5 ± 1.3 (mmol/|L) among diabetic and 4.7 ± 0.9 (mmol/L) among non-diabetics was recorded. There is a decrease in neutrophil phagocytic function with a mean ± SD of 5.4 ± 2.1 (Fmol/ phag) in diabetics compared to 9.2 ± 2.1 (Fmol/phag) in non-diabetics. Similarly, complement (CH 50) function and C-reactive protein were significantly lower in diabetics when compared to non-diabetics (p<0.001). There was a significant difference in IL-6 concentration between diabetics and non-diabetics groups, but no significant difference was observed in TNF-α, IL-4 and IL-10 concentrations between study groups (p>0.05). TNF-α and IL-6 was significantly higher in diabetics with cardiovascular disorders compared to non-diabetics subjects with cardiovascular disorders (p<0.001). Conclusion. Findings from this study revealed the association of complement, neutrophil phagocytic function, CRP and IL-6 among septic diabetic patients,. In addition TNF-α and IL-6 expression was higher in DM patients with cardiovascular disorders.
Źródło:
European Journal of Clinical and Experimental Medicine; 2019, 3; 229-235
2544-2406
2544-1361
Pojawia się w:
European Journal of Clinical and Experimental Medicine
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Free electrons: fundamental interactions, applications and data needs
Autorzy:
Christophorou, L.
Powiązania:
https://bibliotekanauki.pl/articles/148509.pdf
Data publikacji:
2003
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
applications
data
interactions
low-energy electrons
molecules
Opis:
In spite of the important recent advances in the field of low-energy electron interactions with atoms and molecules, there still exist fundamental needs and challenges, some of which are generic in their basic and applied significance. These include measurements of cross sections for a number of fundamental low-energy electron–ground-state molecule interaction processes such as vibrational excitation (direct and indirect) and dissociation into neutral fragments, studies of low-energy electron–excited molecule interactions, investigations of low-energy electron interactions with radicals and transient species, and measurements of electron energy losses in electron–molecule collision processes. They also include studies for linking of knowledge on isolated electron–molecule interactions to that in the condensed phases of matter, and the systematic and quantitative exploration of the interactions of low-energy electrons with molecular and macromolecular biological structures.
Źródło:
Nukleonika; 2003, 48, 2; 67-74
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł

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