1
|
Abstract
Künstliche Ultramarine werden mit Hilfe der EPR im X- und Q-Band untersucht. Es wird gezeigt, daß der Paramagnetismus durch 4 Schwefelradikale, die durch die chemische Behandlung mit NaCN abgebaut werden können, entsteht.
Collapse
Affiliation(s)
- R. Böttcher
- Physikalisches Institut der Universität Leipzig, Abteilung Struktur der Materie
| | - S. Wartewig
- Physikalisches Institut der Universität Leipzig, Abteilung Struktur der Materie
| | - W. Windsch
- Physikalisches Institut der Universität Leipzig, Abteilung Struktur der Materie
| | - A. Zschunke
- Physikalisches Institut der Universität Leipzig, Abteilung Struktur der Materie
| |
Collapse
|
2
|
Hergeth WD, Alig I, Lange J, Lochmann JR, Scherzer T, Wartewig S. On the molecular mechanism of clouding in aqueous solution of poly(oxyethylene)-poly(oxypropylene)-poly(oxyethylene) triblock copolymers. ACTA ACUST UNITED AC 2011. [DOI: 10.1002/masy.19910520129] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
3
|
Zbytovská J, Vávrová K, Kiselev M, Lessieur P, Wartewig S, Neubert R. The effects of transdermal permeation enhancers on thermotropic phase behaviour of a stratum corneum lipid model. Colloids Surf A Physicochem Eng Asp 2009. [DOI: 10.1016/j.colsurfa.2009.09.025] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
|
4
|
Zbytovská J, Kiselev M, Funari S, Garamus V, Wartewig S, Palát K, Neubert R. Influence of cholesterol on the structure of stratum corneum lipid model membrane. Colloids Surf A Physicochem Eng Asp 2008. [DOI: 10.1016/j.colsurfa.2008.06.032] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
5
|
Kessner D, Ruettinger A, Kiselev MA, Wartewig S, Neubert RHH. Properties of ceramides and their impact on the stratum corneum structure. Part 2: stratum corneum lipid model systems. Skin Pharmacol Physiol 2008; 21:58-74. [PMID: 18187965 DOI: 10.1159/000112956] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2007] [Accepted: 07/23/2007] [Indexed: 11/19/2022]
Abstract
The stratum corneum (SC) represents the outermost layer of the mammalian skin, exhibits the main skin barrier and plays an important role in the water penetration pathway through the SC. Knowing the structure and properties of the SC at the molecular level is essential for studying drug penetration through the SC and for the development of new dermal drug delivery systems. Therefore, research interest is focused on the SC lipid matrix and on water diffusion through it. Thus, the ultimate aim is to design a lipid mixture that mimics the barrier properties of the human SC to a high extent and that can substitute the SC in drug delivery systems. This review summarizes various studies performed on either isolated animal or human ceramide based SC model systems, coming to the result that using synthetic lipids with a well-defined architecture allows good extrapolation to the in vivo situation. This review is the continuation of part 1 that is focused on a detailed description of the thermotropic and/or lyotropic phase behaviour of single ceramide types obtained by various experimental techniques. The objective of part 2 is to reflect the numerous studies on SC lipid model systems, namely binary, ternary and multicomponent systems, during the last decade. In this context, neutron diffraction as a prospective tool for analyzing the internal membrane structure is addressed in particular. Based on these new insights, current SC models are presented, whose validations are still under discussion. A profound knowledge about SC lipid organization at the molecular level is still missing.
Collapse
Affiliation(s)
- D Kessner
- Institute of Pharmacy, Martin Luther University Halle-Wittenberg, Halle-Saale, Germany
| | | | | | | | | |
Collapse
|
6
|
Wartewig S, Neubert RHH. Properties of Ceramides and Their Impact on the Stratum Corneum Structure: A Review. Skin Pharmacol Physiol 2007; 20:220-9. [PMID: 17587886 DOI: 10.1159/000104420] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2007] [Accepted: 04/27/2007] [Indexed: 11/19/2022]
Abstract
The lipid matrix of the stratum corneum (SC) is the major diffusion-rate-limiting pathway by which most drugs intracellularly pass the SC. The major lipid classes extracted from the SC are ceramides, cholesterol and free fatty acids. Ceramides that comprise nine subclasses play a crucial role in maintaining the barrier function of the skin. A profound knowledge of the physical properties of ceramides is essential for a deeper understanding of the impact of each ceramide species on the barrier function. The review summarizes the thermotropic and/or lyotropic behaviour of sphingosine-type ceramides (CER AS, CER NS) and phytosphingosine-type ceramides (CER AP, CER NP) revealed by differential scanning calorimetry, X-ray diffraction, Fourier transform infrared spectroscopy and Fourier transform Raman spectroscopy in past decades. Polymorphism is a characteristic feature of ceramides. At physiological temperatures, all crystalline phases of ceramides exhibit lamellar structures with highly ordered hydrocarbon chains. The differential behaviour of the head groups of ceramides may be an important determinant for the skin barrier function.
Collapse
Affiliation(s)
- S Wartewig
- Institute of Applied Dermatopharmacy, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
| | | |
Collapse
|
7
|
Zemlyanaya EV, Kiselev MA, Zbytovska J, Almasy L, Aswal VK, Strunz P, Wartewig S, Neubert R. Structure of unilamellar vesicles: Numerical analysis based on small-angle neutron scattering data. CRYSTALLOGR REP+ 2006. [DOI: 10.1134/s1063774506070054] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|
8
|
Jäckel A, Schmelzer CEH, Wartewig S, Neubert RHH. Sublimation of antimycotic agents as proved by various analytical methods. Pharmazie 2006; 61:1045-7. [PMID: 17283666] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Qualitative and quantitative results demonstrate that the pure substances amorolfine base, amorolfine hydrochloride, two selected morpholine derivatives and terbinafine hydrochloride are clearly able to sublimate. As amorolfine hydrochloride is also capable to sublimate from galencial forms laquer and cream in this experimental setup, a clinical relevance of sublimation phenomenon at least for topical treatment of onychomycosis has to be considered. This phenomenon could be one reason for advantageous clinical and mycological cure rates of amorolfine nail laquer to comparable topical products reported in the literature.
Collapse
Affiliation(s)
- A Jäckel
- Medical Department, Galderma Laboratorium GmbH, Düsseldorf, Germany
| | | | | | | |
Collapse
|
9
|
Welter M, Kröber T, Wartewig S, Windsch W. ENDOR investigations of the structure of glycine radicals in X-irradiated tri-glycine sulphate and of structural changes near the ferroelectric phase transition point. Mol Phys 2006. [DOI: 10.1080/00268977800102431] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- M. Welter
- a Sektion Physik der Karl-Marx-Universität , DDR 701 , Leipzig , German Democratic Republic
| | - T. Kröber
- a Sektion Physik der Karl-Marx-Universität , DDR 701 , Leipzig , German Democratic Republic
| | - S. Wartewig
- a Sektion Physik der Karl-Marx-Universität , DDR 701 , Leipzig , German Democratic Republic
| | - W. Windsch
- a Sektion Physik der Karl-Marx-Universität , DDR 701 , Leipzig , German Democratic Republic
| |
Collapse
|
10
|
Neubert RHH, Gensbügel C, Jäckel A, Wartewig S. Different physicochemical properties of antimycotic agents are relevant for penetration into and through human nails. Pharmazie 2006; 61:604-7. [PMID: 16889067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
This article reports the characterization of the physicochemical properties of two important antifungal topical drugs, amorolfine and ciclopirox. Furthermore, the release of the drugs from commercial lacquer formulations for treatment of onychomycosis was studied using the online FTIR-ATR technique. Based on the physicochemical background of these two drugs and their release from commercial lacquer formulations for treatment of onychomycosis, the suitability of these drugs for optimized local antifungal therapy to human nails is discussed. Amorolfine appears to be more suitable for drug delivery to human nails because it penetrates into the nails via the hydrophilic pathway. Furthermore amorolfine penetrates very well into fungal cells, due to the pH value of the nail, as well as the pKa value of this antimycotic agent and the lipophilic properties of its base form.
Collapse
Affiliation(s)
- R H H Neubert
- School of Pharmacy, Institute of Pharmaceutical Technology and Biopharmaceutics, Martin-Luther-University, Halle-Wittenberg, Germany.
| | | | | | | |
Collapse
|
11
|
|
12
|
Zbytovská J, Kiselev MA, Funari SS, Garamus VM, Wartewig S, Neubert R. Influence of phytosphingosine-type ceramides on the structure of DMPC membrane. Chem Phys Lipids 2005; 138:69-80. [PMID: 16202987 DOI: 10.1016/j.chemphyslip.2005.08.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2005] [Revised: 08/09/2005] [Accepted: 08/17/2005] [Indexed: 11/26/2022]
Abstract
The present paper describes the influence of the ceramides with phytosphingosine base, N-stearoylphytosphingosine (Cer[NP]) and alpha-hydroxy-N-stearoylphytosphingosine (Cer[AP]), on the structure and properties of multilamellar (MLVs) and unilamellar vesicles (ULVs) of dimyristoylphosphatidylcholine (DMPC). The lamellar repeat distance, D, has been measured at various temperatures using small angle X-ray diffraction. The incorporation of ceramides into the DMPC membrane causes larger D compared to pure DMPC membrane. For both ceramide types, at 32 degrees C, there is a linear relationship between the D value and the ceramide concentration. However, there is no such dependence at 13 or 60 degrees C. Unlike Cer[AP], Cer[NP] induces a new phase with a repeat distance of 38.5A. The membrane thickness and the vesicle radius of ULVs in water and in sucrose solution were calculated from small angle neutron scattering curves. Phytosphingosine ceramides increase both the membrane thickness and the radius in comparison to pure DMPC ULVs. The stability of ULVs in time was studied by dynamic light scattering. Both ceramides induce an aggregation of the ULVs into micrometer sized non-multilamellar structures in pure water. Presence of sucrose in the environment averts the vesicle aggregation.
Collapse
Affiliation(s)
- J Zbytovská
- Department of Pharmacy, Martin-Luther-University Halle-Wittenberg, Wolfgang-Langenbeck Str. 4, D-06120 Halle/Saale, Germany.
| | | | | | | | | | | |
Collapse
|
13
|
Fechner PM, Wartewig S, Kiesow A, Heilmann A, Kleinebudde P, Neubert RHH. Interaction of water with different cellulose ethers: a Raman spectroscopy and environmental scanning electron microscopy study. J Pharm Pharmacol 2005; 57:689-98. [PMID: 15969923 DOI: 10.1211/0022357056109] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Different non-ionic cellulose ethers like methyl cellulose (MC), hydroxypropyl cellulose (HPC) and hydroxypropylmethyl cellulose (HPMC) were investigated. The characterization of the cellulose ethers was carried out by thermogravimetry and sorption/desorption isotherms. Differences in the properties of the cellulose ether films were described by time-dependent contact angle measurements. Changes in molecular structure of the raw materials, gels and films caused by water contact were studied using Raman spectroscopy. Differences between the substitution types and changes due to the gel or film formation were observed. An environmental scanning electron microscopy (ESEM) technique was used to distinguish the morphological behaviour of the cellulose ether films in contact with water. Based on in-situ ESEM experiments, the swelling and drying behaviour of the various stages of cellulose ether films (film-hydrated film-dried film) were quantified by using image analysis.
Collapse
Affiliation(s)
- P M Fechner
- Institute of Pharmaceutics and Biopharmaceutics, Martin Luther University Halle-Wittenberg, W.-Langenbeck-Strasse 4, 06120 Halle, Germany.
| | | | | | | | | | | |
Collapse
|
14
|
Kiselev MA, Ryabova NY, Balagurov AM, Dante S, Hauss T, Zbytovska J, Wartewig S, Neubert RHH. New insights into the structure and hydration of a stratum corneum lipid model membrane by neutron diffraction. Eur Biophys J 2005; 34:1030-40. [PMID: 16032423 DOI: 10.1007/s00249-005-0488-6] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2004] [Revised: 03/03/2005] [Accepted: 04/26/2005] [Indexed: 11/25/2022]
Abstract
The structure and hydration of a stratum corneum (SC) lipid model membrane composed of N-(alpha-hydroxyoctadecanoyl)-phytosphingosine (CER6)/cholesterol (Ch)/palmitic acid (PA)/cholesterol sulfate (ChS) were characterized by neutron diffraction. The neutron scattering length density across the SC lipid model membrane was calculated from measured diffraction peak intensities. The internal membrane structure and water distribution function across the bilayer were determined. The low hydration of the intermembrane space is a major feature of the SC lipid model membrane. The thickness of the water layer in the SC lipid model membrane is about 1 A at full hydration. For the composition 55% CER6/25% Ch/15% PA/5% ChS, in a partly dehydrated state (60% humidity) and at 32 degrees C, the lamellar repeat distance and the membrane thickness have the same value of 45.6 A . The hydrophobic region of the membrane has a thickness of 31.2 A . A decrease of the Ch content increases the membrane thickness. The water diffusion through the SC lipid model multilamellar membrane is a considerably slow process relative to that through phospholipid membranes. In excess water, the membrane hydration follows an exponential law with two characteristic times of 93 and 44 min. At 81 degrees C and 97% humidity, the membrane separates into two phases with repeat distances of 45.8 and 40.5 A . Possible conformations of CER6 molecules in the dry and hydrated multilayers are discussed.
Collapse
Affiliation(s)
- M A Kiselev
- Institute of Pharmaceutical Technology and Biopharmacy, Martin Luther University, Halle, Saale, Germany.
| | | | | | | | | | | | | | | |
Collapse
|
15
|
Kiselev M, Zbytovska J, Matveev D, Wartewig S, Gapienko I, Perez J, Lesieur P, Hoell A, Neubert R. Influence of trehalose on the structure of unilamellar DMPC vesicles. Colloids Surf A Physicochem Eng Asp 2005. [DOI: 10.1016/j.colsurfa.2004.09.017] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
16
|
Uhr M, Wartewig S, Unruh T, Richter H. Physicochemical characterization of silicon-containing glycolipids by DSC, FT-Raman spectroscopy and X-ray diffraction. Chem Phys Lipids 2003; 124:1-13. [PMID: 12787939 DOI: 10.1016/s0009-3084(03)00021-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Derivatives of dimethylalkylchlorosilanes are novel substances which may be used in formulations for drug targeting. In order to design their properties it is essential to perform physicochemical characterization. For this purpose, a combination of differential scanning calorimetry (DSC), FT-Raman spectroscopy and X-ray diffraction is well suited. For the starting material dimethyloctadecylchlorosilane (DMOC), the assignment of Raman bands is discussed. The influence of sugar-containing head groups on the structures of the hydrocarbon chains of 1-O-(dimethyldodecylsilyl)-[2,3,4,6-tetra-O-acetyl-beta-D-glucopyranoside] and 1-O-(dimethyloctadecylsilyl)-[2,3,4,6-tetra-O-acetyl-beta-D-glucopyranoside] was investigated using the band position of the symmetric methylene mode. The temperature dependence of conformationally sensitive bands in the CH(2)-stretching region (2800-2900 cm(-1)), C-C-stretching region (1000-1150 cm(-1)) and CH(3)-rocking region (830-900 cm(-1)) was studied to characterize the state of order of the alkyl chains. Using X-ray diffraction, the repeating distances of layered structures was determined. The phase transitions occurring were found to be completely reversible. The subcell of DMOC shows an orthorhombic perpendicular packing structure in the crystalline state.
Collapse
Affiliation(s)
- M Uhr
- Department of Pharmacy, Institute of Pharmaceutical Chemistry, Martin-Luther-Universität Halle/Wittenberg, Wolfgang-Langenbeck-Str. 4, 06120 Halle, Germany
| | | | | | | |
Collapse
|
17
|
Abstract
Small-angle neutron and X-ray scattering, dynamic light scattering, X-ray diffraction coupled with differential scanning calorimetry, and Raman spectroscopy were applied to investigate unilamellar (ULVs) and multilamellar (MLVs) dimyristoylphosphatidylcholine (DMPC) vesicles in aqueous sucrose solutions with sucrose concentrations from 0 to 60% w/w. In case of ULVs, the addition of sucrose decreases the polydispersity of vesicle population. A minimum value of polydispersity was found at 20% sucrose. For sucrose concentration from 0 to 35% oligolamellar vesicles in the ULV population have a minimum presence. Vesicles with 5-10% sucrose exhibit the best stability in time. For the case of MLVs, sucrose influences the temperature of the phase transitions, but the internal membrane structure remains unchanged.
Collapse
Affiliation(s)
- M A Kiselev
- Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research (JINR), 141980 Dubna, Moscow Region, Russia.
| | | | | | | | | | | | | |
Collapse
|
18
|
Pohle W, Selle C, Rettig W, Heiser U, Dobner B, Wartewig S. Phase transitions and hydrogen bonding in a bipolar phosphocholine evidenced by calorimetry and vibrational spectroscopy. Arch Biochem Biophys 2001; 396:151-61. [PMID: 11747292 DOI: 10.1006/abbi.2001.2593] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
As a model for natural archaebacterial bolalipids, we have synthesized omega-hydroxybehenylphosphocholine (HBPC, HO-(CH(2))(22)-OP(O(-)(2))O-(CH(2))(2)-N+(CH(3))(3)) and investigated it, by Fourier-transform infrared and Raman spectroscopy and differential scanning calorimetry, both as fully hydrated dispersions (varying temperature) and as aligned films (varying hydration) in terms of particular structural features predestining such bipolar lipids for their occurrence in extremophilic organisms. The phase behavior of HBPC in dispersions depends on sample pretreatment as it comprises metastabilities in annealed samples. However, main transition proceeds consistently near 81 degrees C. Some (extra) deal of headgroup (phosphate) hydration accompanying a gel-gel phase transition near 66 degrees C appears to precede chain melting. Studies with HBPC films revealed lamellar interdigitated-like solid phases with an extraordinarily strong omega-OH--OPO(-) omega-OH--OPO(-) omega-OH hydrogen-bond pattern formed along both sides of the resulting monolayers. The "clamping" effect inherent to such structures provides a clue to explain the relatively high main-transition temperature of HBPC assemblies.
Collapse
Affiliation(s)
- W Pohle
- Institute of Molecular Biology, Friedrich-Schiller University Jena, Winzerlaer Strasse 10, D-07745 Jena, Germany.
| | | | | | | | | | | |
Collapse
|
19
|
Abstract
The ring-opening polymerization of epsilon-caprolactone, delta-valerolactone (VL) and D,L-lactide, respectively, in the presence of different proportions of hydroxyapatite (HA) was catalyzed by stannous (II)octoate (SnOct2) at 130 degrees C and resulted in composites. The lactones were almost completely converted to the polymers within a reaction time of 70 up to 240 min. The number-average molecular weights Mn as determined by size exclusion chromatography decreased with increasing content of HA. The initiating efficiency of HA as calculated from the difference of the polymerization degrees P. obtained with and without HA turned out to be relatively low with ca. 11 to 0.5% for 1 to 80 wt% HA, respectively. For the polymerization of VL, the initiating efficiency of HA was on the average threefold higher. The quantitative proof of non-extractable polymer on HA by means of thermogravimetric analysis, fourier transform infrared spectroscopy with photoacoustic detection and differential scanning calorimetry confirmed the initiating efficiency of HA as mentioned above. This poly(lactone) can be debound from HA by treatment with aqueous HCl. Hence it is assumed to be ionically bound.
Collapse
Affiliation(s)
- E Helwig
- Institute of Technical and Macromolecular Chemistry, Martin-Luther-University, Halle-Wittenberg, Halle/Saale, Germany
| | | | | | | | | | | |
Collapse
|
20
|
Wohlrab J, Vollmann A, Wartewig S, Marsch WC, Neubert R. Noninvasive characterization of human stratum corneum of undiseased skin of patients with atopic dermatitis and psoriasis as studied by Fourier transform Raman spectroscopy. Biopolymers 2001; 62:141-6. [PMID: 11343282 DOI: 10.1002/bip.1006] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Etiopathogenetic regulatory disorders of epidermal metabolism and the subsequent changes in the molecular pattern of the stratum corneum play an important role in the clinical differentiation of particular dermatoses (e.g., psoriasis, atopic dermatitis). In this study we present in vitro Fourier transform Raman spectra of the stratum corneum from healthy skin, as well as from clinically undiseased skin of the right heel of atopic and psoriatic volunteers. Differences in the averaged spectra were detected, particularly in the spectral ranges of 1112-1142 (lipid band), 1185-1220, and 1394-1429 cm(-1). By using the first derivative of the averaged spectra and/or a statistical evaluation of the spectroscopic data it was possible to distinguish the skin types examined.
Collapse
Affiliation(s)
- J Wohlrab
- Department of Dermatology, Martin-Luther-University Halle-Wittenberg, Ernst-Kromayer-Strasse 5-6, D-06097 Halle, Germany.
| | | | | | | | | |
Collapse
|
21
|
Meyer N, Nestler K, Engisch L, Marx G, Füting M, Kiesow A, Heilmann A, Wartewig S, Kleinebudde P. Raman spectroscopic surface characterization of cellulose derivatives. Fresenius J Anal Chem 2001; 370:789-91. [PMID: 11508470 DOI: 10.1007/s002160100864] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
First results of experiments on the surface characterization of cellulose derivatives are presented. Different water contents of the surface of microcrystalline cellulose have been investigated by means of Raman spectroscopy, SERS, and environmental scanning electron microscopy (ESEM).
Collapse
Affiliation(s)
- N Meyer
- TU Chemnitz, Physikalische Chemie, Chemnitz, Germany
| | | | | | | | | | | | | | | | | |
Collapse
|
22
|
Hanh BD, Neubert RH, Wartewig S, Lasch J. Penetration of compounds through human stratum corneum as studied by Fourier transform infrared photoacoustic spectroscopy. J Control Release 2001; 70:393-8. [PMID: 11182209 DOI: 10.1016/s0168-3659(00)00371-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The penetration of the lipophilic model permeant, 1-cyanodecane, into isolated human stratum corneum (SC) was followed nondestructively by step-scan Fourier transform infrared (FTIR) photoacoustic spectroscopy (PAS) with phase modulation technique. The uptake of the compound in the SC was quantified by monitoring the alterations in the spectra in the course of the penetration using multivariate analysis. Step-scan technique in conjunction with phase modulation offers the possibility for controllable depth profiling (sampling depth up to 30 microm) during the penetration process. Based on Fick's second law and assuming a virtually layered structure of the membrane, depth-dependent diffusion coefficients were derived by numerical fitting of the spectroscopic data. For 1-cyanodecane, the diffusion coefficient in the inner region of the SC is 1.6-fold that measured in the outer region.
Collapse
Affiliation(s)
- B D Hanh
- School of Pharmacy, Institute of Pharmaceutics and Biopharmaceutics, Martin-Luther-University Halle-Wittenberg, Wolfgang-Langenbeck-Strasse 4, D-06120 Halle/Saale, Germany
| | | | | | | |
Collapse
|
23
|
Abstract
The sodium oleate-oleic acid (1:1) complex (NaHOl(2)) is characterized using X-ray diffraction, FT-IR photoacoustic spectroscopy, FT-Raman spectroscopy, and DSC. The special arrangement of hydrogen-bonded pairs of carboxylic acid and carboxylate groups into unique "head-group" is supported by frequency shifts and partial or total disappearance of characteristic vibrations of carboxylic acid dimer and of carboxylate groups. The well-ordered state of hydrocarbon chains is demonstrated by the existence of sharp Raman bands in the C-C stretching region (1000-1150 cm-1) and other conformationally sensitive modes. The FT-Raman results suggest that the transition at about 32 degrees C involves the cooperative melting of methyl- and carboxyl/carboxylate-sided hydrocarbon chains. From the X-ray diffraction data it is clear that this transition is associated with the disintegration of the hydrogen-bonded carboxylate-carboxylic acid complex, followed by the separate formation of oleic acid and sodium oleate. The packing of hydrocarbon chain in the acid-soap complex is different from the parent oleic acid or sodium oleate. The hydrocarbon chains in the NaHOl(2) form more stable packing (O subcell) in comparison to that of oleic acid. A temperature composition phase diagram is presented.
Collapse
Affiliation(s)
- P Tandon
- Department of Pharmacy, Martin-Luther-Universität Halle-Wittenberg, Wolfgang-Langenbeck-Str.4, D-06120 /Saale, Halle, Germany
| | | | | | | | | |
Collapse
|
24
|
Hanh BD, Neubert RH, Wartewig S, Christ A, Hentzsch C. Drug penetration as studied by noninvasive methods: fourier transform infrared-attenuated total reflection, fourier transform infrared, and ultraviolet photoacoustic spectroscopy. J Pharm Sci 2000; 89:1106-13. [PMID: 10944375 DOI: 10.1002/1520-6017(200009)89:9<1106::aid-jps2>3.0.co;2-j] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The penetration of the drugs dithranol and methoxsalen from semisolid Vaseline formulation into an artificial dodecanol-collodion membrane was followed by three spectroscopic methods; they are, step-scan Fourier transform infrared (FTIR) photoacoustic spectroscopy (PAS) with phase modulation, FTIR-attenuated total reflection (FTIR-ATR), and ultraviolet (UV) PAS. The uptake of the drug in the membrane was quantified by monitoring the dependence of an appropriate drug band on the penetration time. The PAS experiments were carried out with various modulation frequencies for generating various sampling depths. Based on Fick's second law, the diffusion coefficient was derived by numerical fitting of the experimental data. It appears that the diffusion coefficient for the drug in the membrane depends on the distance. The comparative studies demonstrate that FTIR-ATR is favored for permeation studies, whereas the PAS techniques are capable of providing the drug penetration profile in the membrane. Thus, extended experimental data are available for new insight into the penetration process. However, because of the photacoustic cells at hand, PAS is only suitable for in vitro studies.
Collapse
Affiliation(s)
- B D Hanh
- Martin-Luther-University, School of Pharmacy, Institute of Pharmaceutics and Biopharmaceutics, Wolfgang-Langenbeck-Str. 4, D-06120 Halle/Saale, Germany
| | | | | | | | | |
Collapse
|
25
|
Hanh BD, Wartewig S. Investigation of drug release from suspension using FTIR-ATR technique: part I. Determination of effective diffusion coefficient of drugs. Int J Pharm 2000; 204:145-50. [PMID: 11011998 DOI: 10.1016/s0378-5173(00)00488-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Fourier transform infrared attenuated total reflectance (FTIR-ATR) spectroscopy was used to study directly the release of drug particles (ketoconazole) in a liquid medium (paraffinum liquidum). In the case of the release experiment, the formulation is placed on the ATR crystal and the acceptor membrane on the top of the ointment. The decrease of the drug content in the sediment near the interface ATR crystal-formulation in the course of the release process was quantified by monitoring the changes of the IR spectrum in relevant spectral ranges using multivariate analysis. A mathematical model based on Fick's second law with appropriate initial and boundary conditions was applied in order to determine the diffusion coefficient of the drug in the liquid medium. Knowing this value, it is possible to calculate the effective diffusion coefficient of the drug in heterogeneous semisolid formulation (Vaseline) as a function of the volume fraction of the solid phase.
Collapse
Affiliation(s)
- B D Hanh
- Department of Pharmacy, Institute of Pharmaceutics and Biopharmaceutics, Martin-Luther University, Halle/Saale, Germany
| | | |
Collapse
|
26
|
Hanh BD, Neubert RH, Wartewig S. Investigation of drug release from suspension using FTIR-ATR technique: part II. Determination of dissolution coefficient of drugs. Int J Pharm 2000; 204:151-8. [PMID: 11011999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
Fourier transform infrared attenuated total reflectance (FTIR-ATR) spectroscopy was applied to a release experiment in order to determine the dissolution coefficient of drug particles in heterogeneous semisolid formulations. The drug release experiment was carried out using ketoconazole suspended in Vaseline with various amounts of paraffinum liquidum as donor and an artificial dodecanol-collodion (DDC) membrane as acceptor compartment. Monitoring changes in IR bands due to ketoconazole the decrease of the drug content near the ATR crystal ointment was followed as a function of time. A mathematical model based on Fick's second law with a source term was used to derive the apparent dissolution coefficient Kdis by numerical fitting the experimental data. It was found that Kdis is dependent on the fraction of paraffinum liquidum in the suspension. Taking into account all experimental parameters required, the transport process was simulated and discussed in terms of drug concentration- time and drug concentration- distance profiles. Calculating the area under the mass-time curve it was tried to predict the 'dermal bioavailability' in the acceptor (AUCa).
Collapse
Affiliation(s)
- B D Hanh
- Department of Pharmacy, Institute of Pharmaceutics and Biopharmaceutics, Martin-Luther University, Halle/Saale, Germany
| | | | | |
Collapse
|
27
|
Tandon P, Neubert R, Wartewig S. Thermotropic phase behaviour of sodium oleate as studied by FT-Raman spectroscopy and X-ray diffraction. J Mol Struct 2000. [DOI: 10.1016/s0022-2860(00)00441-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|
28
|
Pallas P, Wartewig S, Zimmermann I, Richter H. Characterization of dimethyldiacyloxysilanes by differential scanning calorimetry, Raman scattering and X-ray diffraction. Pharmazie 2000; 55:503-7. [PMID: 10944777] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
The phase behaviour of diacyloxydimethylsilanes (DMS Cn; n = 10, 12, 14, 16, 18, 20, 22) was investigated by differential scanning calorimetry, X-ray diffraction and Raman spectroscopy. All DMS Cn melt from a crystalline phase to an isotropic liquid with a single sharp transition. On cooling, the homologous DMS C16 up to DMS C22 show a characteristic monotropic phase (L beta'H). In contrast to the calorimetrical investigations, it was not possible to analyse the monotropic phase of DMS C16 by X-ray diffraction. This behaviour is due to a two-phase region (gel phase--crystalline phase). The Raman spectra of all DMS are very similar. Only in the low frequency range we find different bands of the longitudinal acoustic modes. The Raman measurements demonstrate undoubtedly that in the solid state the alkyl chains are in all-trans conformation. The factor group splitting of the CH2 scissoring Raman mode show that the DMS Cn are arranged in a subcell packing with two molecules per unit cell. The highly ordered all-trans structure of the alkyl chains is present up to the melting transition. On melting there are changes in different regions of the Raman spectra: C-H stretching, CH2 scissoring mode, C-C skeletal stretching, CH3 rocking and longitudinal acoustic modes. On cooling DMS C18 and DMS C20 from the melt to the crystalline state, the gel phase is also proved by Raman scattering. Based on the results of the Raman and X-ray data the gel phase is characterized by a hexagonal subcell packing and by an ordered structure of the alkyl chain residues.
Collapse
Affiliation(s)
- P Pallas
- Department of Pharmacy, Martin-Luther-Universität Halle-Wittenberg, Germany
| | | | | | | |
Collapse
|
29
|
Polizos G, Georgoussis G, Kyritsis A, Shilov V, Shevchenko V, Gomza YP, Nesin S, Klimenko N, Wartewig S, Pissis P. Structure and electrical conductivity in novel polyurethane ionomers. POLYM INT 2000. [DOI: 10.1002/1097-0126(200009)49:9<987::aid-pi492>3.0.co;2-b] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
30
|
Kammer S, Albinsky K, Sandner B, Wartewig S. Polymerization of hydroxyalkyl methacrylates characterized by combination of FT-Raman and step-scan FT-i.r. photoacoustic spectroscopy. POLYMER 1999. [DOI: 10.1016/s0032-3861(98)00341-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
31
|
Schendzielorz A, Hanh BD, Neubert RH, Wartewig S. Penetration studies of clotrimazole from semisolid formulation using step-scan FT-IR photoacoustic spectroscopy. Pharm Res 1999; 16:42-5. [PMID: 9950277 DOI: 10.1023/a:1018810526576] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
PURPOSE The aim of this study was to elucidate the potential use of the step-scan FT-IR photoacoustic spectroscopy (PAS) for the non-destructive determination of drug penetration into membranes. METHODS The penetration of clotrimazole from a 10% (w/w) suspension in Vaseline into a dodecanol-collodion acceptor membrane was studied by three methods: the step-scan FT-IR PAS with a phase modulation, a multilayer membrane system, and a modified libration model. Based on Fick's second law, the diffusion coefficient of the drug in the membrane was derived by numerical fitting of the experimental data. RESULTS The three methods applied provided almost the same diffusion coefficient D = 2.2 10(-9) cm2/s for clotrimazole in the membrane. Because of the non-destructive mode of operation, the accuracy of results obtained by FT-IR PAS is much better than that attainable by other two methods. CONCLUSIONS Step-scan FT-IR photoacoustic spectroscopy in conjunction with a phase modulation is useful to determine the penetration of drug through membranes. The fact that samples can be investigated without elaborate preparation is an advantage of this spectroscopic technique.
Collapse
Affiliation(s)
- A Schendzielorz
- Martin-Luther-University, School of Pharmacy, Institute of Pharmaceutics and Biopharmaceutics, Halle/Saale, Germany
| | | | | | | |
Collapse
|
32
|
Sandner B, Tübke J, Werther A, Sandner R, Wartewig S, Shashkov S. Ionic association in gel electrolytes of varied polarity as studied by FT Raman spectroscopy. Electrochim Acta 1998. [DOI: 10.1016/s0013-4686(97)10054-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|
33
|
Sandner B, Weinkauf A, Reiche A, Siury K, Tübke J, Wartewig S, Shashkov S. Properties of gel electrolytes based on crosslinked copolymers of oligo(ethylene glycol) dimethacrylate and cyanomethyl methacrylate. Electrochim Acta 1998. [DOI: 10.1016/s0013-4686(97)10028-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
|
34
|
Neubert R, Rettig W, Wartewig S, Wegener M, Wienhold A. Structure of stratum corneum lipids characterized by FT-Raman spectroscopy and DSC. II. Mixtures of ceramides and saturated fatty acids. Chem Phys Lipids 1997; 89:3-14. [PMID: 9353900 DOI: 10.1016/s0009-3084(97)00049-2] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Fourier transform (FT) Raman spectroscopy and differential scanning calorimetry (DSC) were used to study the thermotropic phase behaviour of mixtures of ceramides type IV (CER) and stearic acid (SA). For comparison the melting behaviour of SA was re-examined. The Raman spectra of all mixtures in the solid state show sharp bands associated with trans sequencies of the alkyl chain residues of both lipids. These features demonstrate that the hydrocarbon chains are highly ordered in the mixtures, too. The temperature dependence of the conformationally sensitive bands is used to estimate the degree of order in terms of the relative population of trans and gauche conformations. The DSC heating curves for the mixtures show two endothermic transitions which are typical for eutectic melting. The factor group splitting of the CH2 scissoring mode, arising from the orthorhombic subcell packing of SA, disappears in the course of the eutectic melting of samples with a SA content lower than 90 mol%. Both DSC and Raman spectroscopic studies reveal that CER and SA are immiscible in the solid state. The phase diagram of the system is a simple eutectic type one. The addition of SA to CER shifts the melting temperature of ceramides to lower values. However, though SA is a major component of stratum corneum (SC) it is not efficient enough to increase the fluidity of ceramides.
Collapse
Affiliation(s)
- R Neubert
- Department of Pharmacy, Martin-Luther-University Halle-Wittenberg, Germany
| | | | | | | | | |
Collapse
|
35
|
Wegener M, Neubert R, Rettig W, Wartewig S. Structure of stratum corneum lipids characterized by FT-Raman spectroscopy and DSC. III. Mixtures of ceramides and cholesterol. Chem Phys Lipids 1997; 88:73-82. [PMID: 9297854 DOI: 10.1016/s0009-3084(97)00050-9] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The thermotropic and lyotropic phase behaviour of mixtures of ceramides type IV and cholesterol was investigated using Fourier transform (FT) Raman spectroscopy and differential scanning calorimetry (DSC). In the dry and in the fully hydrated state of these mixtures the DSC-curves exhibit an eutectic melting followed by the melting of the residual solid component. The Raman spectrum of the mixtures is complex, nevertheless, the appearance of the conformationally dependent bands indicates the ordered structure of the hydrocarbon chains. The temperature dependence of the conformationally sensitive bands in the CH2 stretching region (2800-2975 cm-1) and in the chain C-C stretching region (1050-1150 cm-1) was used to estimate the degree of order in terms of the relative population of trans and gauche conformers. The spectrum of the pure cholesterol shows only a weak temperature dependence in the CH2 stretching region and, therefore, the decrease of the intensity of the asymmetric CH2 stretching mode at 2880 cm-1 can be attributed to the melting of the alkyl chains of ceramides. The temperature and width of the phase transition, derived from Raman data, are similar to those of the DSC study.
Collapse
Affiliation(s)
- M Wegener
- Department of Pharmacy, Martin-Luther-University Halle-Wittenberg, Germany
| | | | | | | |
Collapse
|
36
|
Neubert R, Collin B, Wartewig S. Direct determination of drug content in semisolid formulations using step-scan FT-IR photoacoustic spectroscopy. Pharm Res 1997; 14:946-8. [PMID: 9244155 DOI: 10.1023/a:1012168304557] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Affiliation(s)
- R Neubert
- Martin-Luther-University, Department of Pharmacy, Institute of Pharmaceutics and Biopharmaceutics
| | | | | |
Collapse
|
37
|
|
38
|
|
39
|
|
40
|
|
41
|
Wartewig S, Alig I, Bloss P, Hergeth WD, Lange J, Lochmann JR, Scherzer T. Poly(oxyethylen)-poly(oxypropylen)-poly(oxyethylen)-triblockcopolymere. Struktur und dynamik. ACTA ACUST UNITED AC 1990. [DOI: 10.1002/actp.1990.010410707] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
42
|
Wartewig S, Alig I, Hergeth WD, Lange J, Lochmann R, Scherzer T. Spectroscopic investigations on aqueous solution of poly(oxyethylene) - poly(oxypropylene) - poly(oxyethylene) triblockcopolymers. J Mol Struct 1990. [DOI: 10.1016/0022-2860(90)80083-v] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
|
43
|
Alig I, Stieber F, Wartewig S, Bakhramov A, Manučarov Y. Ultrasonic absorption and shear viscosity measurements for solutions of polybutadiene and polybutadiene-block-polystyrene copolymers. POLYMER 1987. [DOI: 10.1016/0032-3861(87)90355-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
|
44
|
Alig I, Lochmann R, Wartewig S. Zu Konformationsuntersuchungen mit der PCILO-Methode an Polymer-Modellmolekülen: n-Pentan. Z PHYS CHEM 1985. [DOI: 10.1515/zpch-1985-26624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
|
45
|
Alig I, Lochmann R, Wartewig S. Zu Konformationsuntersuchungen mit der PCILO-Methode an Polymer-Modellmolekülen: n-Pentan. Z PHYS CHEM 1985. [DOI: 10.1515/zpch-1985-0124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
|
46
|
Hauptmann P, S�uberlich R, Wartewig S. Ultrasonic attenuation and mobility in polymer solutions and dispersions. Poly(vinyl alcohol) and poly(vinyl acetate). Polym Bull (Berl) 1982. [DOI: 10.1007/bf00700288] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
|
47
|
|
48
|
Kirmse R, Wartewig S, Bottcher R. On the existence of a paramagnetic adduct of Ni(II)-bis-(di-n-butyl-diselenocarbamate). An EPR study. Chem Phys Lett 1973. [DOI: 10.1016/0009-2614(73)80584-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
49
|
|
50
|
Hübner H, Sulimow J, Wartewig S, Windsch W. Elektronenspinresonanz an perdeuterierten Triphenylmethylradikalen. Z PHYS CHEM 1963. [DOI: 10.1515/zpch-1963-0115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
|