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1.
Zipora Tietel Sarit Melamed Noy Eretz-Kdosha Ami Guetta Raanan Gvirtz Navit Ogen-Shtern Arnon Dag Guy Cohen 《Molecules (Basel, Switzerland)》2021,26(19)
Jojoba (Simmondsia chinensis (Link) Schneider) wax is used for various dermatological and pharmaceutical applications. Several reports have previously shown beneficial properties of Jojoba wax and extracts, including antimicrobial activity. The current research aimed to elucidate the impact of Jojoba wax on skin residential bacterial (Staphylococcus aureus and Staphylococcus epidermidis), fungal (Malassezia furfur), and virus infection (herpes simplex 1; HSV-1). First, the capacity of four commercial wax preparations to attenuate their growth was evaluated. The results suggest that the growth of Staphylococcus aureus, Staphylococcus epidermidis, and Malassezia furfur was unaffected by Jojoba in pharmacologically relevant concentrations. However, the wax significantly attenuated HSV-1 plaque formation. Next, a complete dose–response analysis of four different Jojoba varieties (Benzioni, Shiloah, Hatzerim, and Sheva) revealed a similar anti-viral effect with high potency (EC50 of 0.96 ± 0.4 µg/mL) that blocked HSV-1 plaque formation. The antiviral activity of the wax was also confirmed by real-time PCR, as well as viral protein expression by immunohistochemical staining. Chemical characterization of the fatty acid and fatty alcohol composition was performed, showing high similarity between the wax of the investigated varieties. Lastly, our results demonstrate that the observed effects are independent of simmondsin, repeatedly associated with the medicinal impact of Jojoba wax, and that Jojoba wax presence is required to gain protection against HSV-1 infection. Collectively, our results support the use of Jojoba wax against HSV-1 skin infections. 相似文献
2.
Differential scanning calorimetry and X-ray diffraction experiments on the phase transformations of cyclohexane dispersed within an emulsifying medium (microsamples 1 μm3 in volume) are presented. The existence of a third metastable crystalline phase (denotedε) besides the already-known phases (two stable phases,α andγ, and two metastable phases,β andδ) is demonstrated. Interpretations of the succession of transformations between these different phases and with the liquid phase, either upon cooling or upon heating, are given. 相似文献
3.
Yu. H. Shevchenko V. A. Logvinenko N. I. Yashchina E. A. Pisarev G. V. Gavrilova 《Journal of Thermal Analysis and Calorimetry》1985,30(2):365-375
The mixed-ligand complex compoundscis- andtrans-[Cr(en)2(NH2CH3)2]Br(B10H10) were synthetized. It was demonstrated by IR spectroscopy that the hydrogen atoms of the anions B10H 10 2? carrying the negative charge interact with the proton of the amino group in the coordinated amine, forming the bond system N-H-H-B. The complex salts obtained have high densities (d 20=1.55 g/cm3 and 1.47 g/cm3 for thecis andtrans isomer, respectively) and high thermal stability 230–250 °C. At 250–270 °C both thecis and thetrans compound dissociate, with simultaneous substitution of two methylamine molecules in the coordination sphere of the chromium(III) ion by the anions Br? and B10H 10 2? . The process is described by the topochemical equationf(α)=(1?α)2/3 (reaction on the interface of the phases), and is characterized by high values of the kinetic parameters: Ea=510–524 kJ/mol, logA=49.9–50.2. We found that the value ofE a for the amine substitution process in thecis compound, determined by evolved gas analysis under non-isothermal conditions, decreases by 220 kJ/mol when the heating rate is increased from 5.0 to 7.5 deg/min. This finding can be explained in that when the heating rate is increased, the intervals in which thecis- trans isomerization and ligand substitution reactions proceed come closer to one another, and finally overlap; the activation energy of the isomerization process then compensates part of the energy required for activation of the ligand substitution process. 相似文献
4.
《Journal of organometallic chemistry》1987,331(1):63-72
Bis(η-cyclopentadienyl)hydridorhenium Cp2ReH undergoes stereospecific trans insertion reactions when treated with monosubstituted acetylenes HCCR (R CO2Me, CN, CF3). The cis alkenyl complexes Cp2Re[η1-(Z)-CHCHR] thus formed isomerize thermally or under acid catalysis to produce the trans isomers Cp2Re[η1-(E)-CHCHR]. When Cp2ReH adds to HCCCOMe only the trans isomer is observed. The regiospecific β-addition of Cp2ReH contrasts with the α-addition of Cp2MoH2 and Cp2WH2. The insertion of acetylenes HCCR′ into the metalcarbon bond of some alkenyl complexes Cp2Re[η1-(E)-CHCHR] affords butadienyl complexes Cp2Re[η1-{(1E,3E)-CHCHR′CHCHR&}] (R,R′ COMe, CO2Me). The (E,E)-configuration of these compounds is deduced from 3J(13-C1H) coupling constants. 相似文献
5.
Thermal effects of theα′→γ structure transformation during heating and that ofγ→α′ during cooling (martensitic transformation) were determined in a series of high-purity iron-nickel alloys containing 20–31 per cent nickel with a differential thermal microanalyzer used as microcalorimeter. The calorimetric calibration of the DTA apparatus was carried out in the range from ?180? up to 950? on the basis of solid-solid or solid-liquid phase transformations of 18 mineral or organic compounds selected as standards. The transformation enthalpies of the thermal effects were calculated from the correlation $$[\Delta {\rm H}]_{T_s }^{T_f } = M/m[Q]_{T_s }^{T_f } $$ whereM: mole mass of the alloy;m: sample mass; \([Q]_{T_s }^{T_f } \) : thermal effect measured between the initial and final temperatures of the transformation. While the nickel content increases from 20 up to 31 percent, the enthalpy of the martensitic transformationΔH γ→α′ decreases from 820 to 310 cal ·mole?1 for cooling, and the enthalpy of the reverse transformationΔH α′→γ for heating decreases from 480 to 330 cal · mole?1. 相似文献
6.
V. V. Burlakov V. S. Bogdanov K. A. Lyssenko A. Spannenberg P. V. Petrovskii W. Baumann P. Arndt M. Kh. Minacheva B. N. Strunin U. Rosenthal V. B. Shur 《Russian Chemical Bulletin》2012,61(1):165-173
The interaction of the Negishi reagent Cp2ZrBun 2 with 1,4-bis(tert-butyl)butadiyne ButC≡C-C≡CBut leads to four products: a five-membered zirconacyclocumulene complex Cp2Zr(η4-ButC4But) (2) synthesized earlier by another method, the previously unknown seven-membered zirconacyclocumulene Cp2Zr[η4-ButC4(But)-C(C2But)=CBut] (3) as well as small amounts of the zirconocene binuclear butatrienyl complex Cp2(Bun)Zr(ButC4But)Zr(Bun)Cp2 (4), and the dimeric acetylide [Cp2ZrC≡CBut]2 (5). The structure of complexes 2–5 was established by X-ray diffraction studies. 相似文献
7.
The dehydroxylation of gibbsite into boehmite was investigated by means of DSC analysis under non-isothermal conditions in the temperature range 453–673 K at heating rates from 2.5 to 20.0 K min?1. Mathematical analysis of the experimental DSC curves revealed the mechanism and kinetics of the gibbsite dehydroxylation process. The kinetic curvesα=f(t) andα=f(T) are sigmoidal in shape; their inflection points and the νm point of the curvesν=f(T) andν=f(T) are interrelated and are defined by the concept of a stationary point. The activation energy for the first stage of gibbsite dehydroxylation in the temperature range 453–673 K is 132.92±8.33–142.26±8.33 kJ mol?1. 相似文献
8.
Maciej Damian Korzyski Moritz Bernhardt Vladyslav Romankov Jan Dreiser Guy Matmon Fabrice Pointillart Boris Le Guennic Olivier Cador Christophe Copret 《Chemical science》2022,13(35):10574
We report a family of organometallic rare-earth complexes with the general formula (COT)M(Cpttt) (where (COT)2− = cyclooctatetraenide, (Cpttt)− = 1,2,4-tri(tert-butyl)cyclopentadienide, M = Y(iii), Nd(iii), Dy(iii) and Er(iii)). Similarly to the prototypical Er(iii) analog featuring pentamethylcyclopentadienyl ligand (Cp*)−, (COT)Er(Cpttt) behaves as a single-ion magnet. However, the introduction of the sterically demanding (Cpttt)− imposes geometric constraints that lead to a simplified magnetic relaxation behavior compared to the (Cp*)− containing complexes. Consequently, (COT)Er(Cpttt) can be viewed as a model representative of this organometallic single-ion magnet architecture. In addition, we demonstrate that the increased steric profile associated with the (Cpttt)− ligand permits preparation, structural characterization and interrogation of magnetic properties of the early-lanthanide complex, (COT)Nd(Cpttt). Such a mononuclear derivative could not be obtained when a (Cp*)− ligand was employed, a testament to larger ionic radius of this early lanthanide ion.Application of steric control principles allows for simplification of the magnetic behavior of an iconic single-ion magnet architecture as well as the preparation of its previously inaccessible representative. 相似文献
9.
Polymorphous modifications (γ-, β- and α-) of the double potassium ytterbium molybdenum oxide K5Yb(MoO4)4 were synthesized by the solid-state method and their structures were studied by X-ray powder diffraction, electron diffraction and high-resolution electron microscopy. DSC analysis shows that the γ→β↔α phase transitions are not accompanied with a significant reconstruction of the palmierite-type structure. All modifications of K5Yb(MoO4)4 are related to the mineral palmierite—K2Pb(SO4)2. The palmierite-type structure is made up of isolated AO4 tetrahedra, which connect the MOn polyhedra into a 3-D framework via common vertices. Cations occupy two crystallographic positions M1 and M2. The γ-phase crystallizes in a monoclinic system (space group C2/c) with unit-cell parameters: a=14.8236(1) Å, b=12.1293(1) Å, c=10.5151(1) Å, β=114.559(1)°, Z=4. The α-phase has space group with unit-cell parameters: a=6.0372(1) Å, c=20.4045(2) Å. The structures of the γ- and α-modification were refined by the Rietveld method (Rwp=6.25%, RI=2.16% and Rwp=9.09%, RI=5.80% for γ- and α-, respectively). In K5Yb(MoO4)4 ytterbium cations occupy M1 while K+ cations occupy M2 and M1 positions of the palmierite-type structure. In the high-temperature (α-) modification the Yb3+ and K+ occupy the M1 site in a statistical manner (M1=0.5Yb3++0.5K+) while in the low-temperature (γ-) modification these cations occupy this site in an ordered way. The intermediate β-phase shows an incommensurate modulated structure. 相似文献
10.
Akiteru WatanabeKaushik Das 《Journal of solid state chemistry》2002,163(1):224-230
This paper describes a cause of the time-dependent degradation of conductivity observed in the representative BIMEVOX phases Bi2Cu0.1V0.9O5.35 (BICUVOX.10) and Bi2Co0.1V0.9O5.35 (BICOVOX.10). In both phases, to date, the following facts were reported: the high-temperature stable γ-type phase transformed reversibly to the low-temperature stable γ′-type phase at 450-500°C through the order-disorder transition without changing to the β-type or α-type phase. In addition, the degradation of conductivity was observed in γ′-BICUVOX.10 at about 420°C. In the present study, it has turned out that a prolonged annealing at 450°C for several hundred hours causes both γ′ phases to change to a new phase with α-Bi4V2O11-related structure. This α-related phase changes promptly to the γ phase on heating (at about 535°C for BICOVOX.10 and at about 485°C for BICUVOX.10); by contrast, the γ′ phase reverts sluggishly to the α-related phase. Since the α-related phase shows far lower conductivity (10−4.8S cm−1 at 430°C for BICUVOX.10), this gradual γ′-to-α transition explains well the time-dependent degradation of conductivity in the γ′ phase reported so far. Namely, the γ′ phase is metastably quenched to room temperature and reverts gradually to the α-related phase upon heat treatment below the α-to-γ transition temperature. 相似文献
11.
Sandra Bolaño Luca Gonsalvi M.a Mar Rodríguez-Rocha Maurizio Peruzzini 《Journal of organometallic chemistry》2008,693(14):2397-2406
The reaction between 1-boranyl-1,3,5-triaza-7-phosphaadamantane ligand N-B-PTA(BH3) and [Cp∗RhCl(μ-Cl)]2 affords [Cp∗Rh{N-B-PTA(BH3)}Cl2] (3) or [Cp∗Rh{N-B-PTA(BH3)}2Cl]Cl (5) containing one or two P-bonded boronated PTA ligands. The hydride [Cp∗Rh{N-B-PTA(BH3)}H2] (8) was also obtained by reaction of 3 with NaBH4 and alternatively by direct hydroboration of [Cp∗Rh(PTA)Cl2] with excess NaBH4. Moderately slow hydrolysis of the N-boranyl rhodium complexes affords dihydrogen, H3BO3 and the corresponding PTA derivatives, including the water-soluble dihydride [Cp∗Rh(PTA)H2] (9). Finally, the reaction of 8 with electron poor alkynes gives the alkene complexes [Cp∗Rh{N-B-PTA(BH3)}(η2-CH2 = CHR)] (R = Ph, 10; C(O)OEt, 11) as a mixture of rotamers η2-coordinated to rhodium without affecting the N-BH3 moiety. The X-ray crystal structures of 3 and 10 were also obtained and are here discussed. 相似文献
12.
N. Sivakumar N. Kanagathara K. Gayathri P. Krishnan G. Anbalagan 《Journal of Thermal Analysis and Calorimetry》2014,115(2):1295-1301
New semi-organic bis(thiourea)silver(I)nitrate (TuAgN) single crystals have been grown from slow evaporation solution growth technique. Single crystal X-ray diffraction study reveals that the crystal belongs to orthorhombic system with the non-centrosymmetric space group C2221 and the calculated cell parameters are a = 33.3455 (6) Å, b = 45.2957 (7) Å, c = 20.3209 (5) Å, α = β = γ = 90°, and V = 30692.8 (10) Å 3. The thermal stability and decomposition behavior of TuAgN compound have been studied by thermogravimetric analysis at three different heating rates 5, 10, and 15 °C min?1. The effective activation energy (E a) and pre-exponential factor (ln A) of thermal decomposition of thiourea from TuAgN compound at three different heating rates are estimated by model free methods: Arrhenius, Flynn–Wall, Kissinger, and Kim–Park. The calculated effective activation energies were found to vary with the fraction (α) reacted. The compensation effect between the (ln A) and (E a) has also been studied. Dielectric properties of TuAgN crystal have been studied in a wide range of frequencies and temperatures. AC conductivity has also been carried out. 相似文献
13.
Two new divalent samarocenes, Cp*′2Sm(THF) (1) and (CpPh3)2Sm(THF) (2) (Cp*′=C5Me4nPr, CpPh3=H2C5Ph3-1,2,4), were synthesized and characterized by 1H NMR and elemental analysis. The activity of 1 and 2 as butadiene polymerisation catalysts was studied, in the presence of MAO and MMAO, and compared to this of Cp*2Sm(THF)2 (3) and (Cp4i)2Sm (4) (Cp*=C5Me5, Cp4i=C5HiPr4), in the same conditions. The 1/MAO system presents the highest activity. The less active 2/MAO system leads to a high cis-1,4 regular structure up to 97%. The MMAO cocatalyst is found very sensitive to the steric hindrance of the samarocenes: the activity decreases from 1/MAO to 1/MMAO, and no activity is observed in the case of complexes 2 and 4, associated to MMAO. Complexes 1 and 2 can be both oxidized with AlMe3 to give the corresponding Sm/Al bimetallics and , respectively. 相似文献
14.
F. Carrasco L.A. Pérez-Maqueda P.E. Sánchez-Jiménez A. Perejón O.O. Santana M.Ll. Maspoch 《Polymer Testing》2013,32(5):937-945
An enhanced general analytical equation has been developed in order to evaluate the kinetic parameters of the thermal degradation of poly(lactic acid) (PLA) at various linear heating rates and at constant rate conditions. This improvement consisted of replacing the n-order conversion function by a modified form of the Sestak-Berggren equation f(α) = c(1?α)nαm, which led to better adjustment of experimental data, and also adequately represented the conventional mechanisms for solid-state processes. The kinetic parameters so obtained have been compared to those determined by conventional differential and isoconversional methods. Given that the thermal degradation of PLA has been argued to be caused by random chain scission reactions of ester groups, the conversion function (α) = 2(α1/2?α), corresponding to a random scission mechanism, has been tested. 相似文献
15.
Johannes Zagermann 《Journal of organometallic chemistry》2009,694(6):862-867
Four differently substituted mixed ligand sandwich complexes CpRu(p-BrC6H4)Tp (3), CpRu(p-BrC6H4)TpMe (4), Cp∗Ru(p-BrC6H4)Tp (5), CpiPrRu(p-BrC6H4)Tp (6), incorporating cyclopentadienyl (Cp) and functionalized tris(pyrazolyl)borate (Tp) ligands, have been synthesized and characterized. Air-stable 6 has been converted to benzoic acid-functionalized CpiPrRu(p-(CO2H)C6H4)Tp (7), which has been structurally characterized in the solid state by X-ray diffraction. Compound 7 may be readily coupled to biomolecules as exemplified by the coupling to phenylalanine-methylester to give CpiPrRu(p-(CO-Phe-OMe)C6H4Tp) (8). In a solid phase peptide synthesis (SPPS), 7 has been coupled to the pentapeptide Enkephalin, to provide CpiPrRu(p-(CO-Tyr-Gly-Gly-Phe-Leu-OH)C6H4Tp) (9) as the first example of a mixed ligand sandwich ruthenium bioconjugate. 相似文献
16.
Hana Palá?ková Jana Holubová Milan Erben 《Journal of organometallic chemistry》2007,692(17):3758-3764
Vanadocene dichloride (1) reacts with sulfur-containing amino acids, cysteine and methionine, giving new complexes with five- or six-membered chelate ring, but the structure of isolated compounds is affected by the pH value of the reaction mixture. Methionine reacts with aqueous 1 in the pH range of 3-8 affording chelate structure [Cp2V(N,O-met)]Cl (4). Similar reaction with cysteine gives two different products depending on pH. In the acidic solution, the complex [Cp2V(O,S-cys)]Cl (2) is present, whereas in neutral media the compound [Cp2V(N,S-cys)] (3) could be identified. On inspection of spectroscopic measurements, particularly EPR and vibrational spectroscopy, it is evident that sulfur atom of amino acid is bonded directly to the vanadium atom of [Cp2V]2+ moiety. For the purpose of comparison the complexes [Cp2V(O,S-mpa)] (5) and [Cp2V(N,S-csam)]+ (6a) with related chelating ligands, 3-mercaptopropionic acid (mpa) and cysteamine (csam), respectively, were prepared and spectroscopically characterized. The structure of the complex [Cp2V(N,S-csam)]BPh4 (6b) was also determined by X-ray diffraction analysis. 相似文献
17.
V. Sangeetha K. Gayathri P. Krishnan N. Sivakumar N. Kanagathara G. Anbalagan 《Journal of Thermal Analysis and Calorimetry》2014,117(1):307-318
Single crystals of melaminium bis (hydrogen oxalate) (MOX) single crystals have been grown from aqueous solution by slow solvent evaporation method at room temperature. X-ray powder diffraction analysis confirms that MOX crystallises in monoclinic system with space group C2/c. The calculated lattice parameters are a = 20.075 ± 0.123 Å b = 8.477 ± 0.045 Å, c = 6.983 ± 0.015 Å, α = 90°, β = 102.6 ± 0.33°, γ = 90° and V = 1,159.73 (Å)3. Thermogravimetric analysis at three different heating rates 10, 15 and 20 °C min?1 has been done to study the thermal decomposition behaviour of the crystal. Non-isothermal studies on MOX reveal that the decomposition occurs in two stages. Kinetic parameters [effective activation energy (E a), pre-exponential factor (ln A)] of each stage were calculated by model-free method: Kissinger, Kim–Park and Flynn–Wall method and the results are discussed. A significant variation in effective activation energy (E a) with conversion progress (α) indicates that the process is kinetically complex. The linear relationship between the ln A and E a was established (compensation effect). DTA analyses were conducted at different heating rates and the activation energy was determined graphically from Kissinger and Ozawa equation. The average effective activation energy is calculated as 276 kJ mol?1 for the crystallization peak. The Avrami exponent for the crystallization peak temperature determined by Augis and Bennett method is found to be 1.95. This result indicates that the surface crystallization dominates overall crystallization. Dielectric study has also been done, and it is found that both dielectric constant and dielectric loss decreases with increase in frequency and is almost a constant at high frequency region. 相似文献
18.
E. Romera Toshikatsu Koga J. S. Dehesa 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1997,42(4):251-257
The present paper addresses the controversial problem on the nonmonotonic behavior of the spherically-averaged momentum density γ(p) observed previously for some ground-state atoms based on the Roothaan-Hartree-Fock (RHF) wave functions of Clementi and Roetti. Highly accurate RHF wave functions of Koga et al. are used to study the existence of extrema in the momentum density γ(p) of all the neutral atoms from hydrogen to xenon. Three groups of atoms are clearly identified according to the nonmonotonicity parameter μ, whose value is either equal to, larger, or smaller than unity. Additionally, it is found that the function p?α γ(p) is (i) monotonically decreasing from the origin for α ≥ 0.75, (ii) convex for α ≥ 1.35, and (iii) logarithmically convex for α ≥ 3.64 for all the neutral atoms with nuclear charges Z = 1–54. Finally, these monotonicity properties are applied to derive simple yet general inequalities which involve three momentum moments 〈p t≥. These inequalities not only generalize similar inequalities reported so far but also allow us to correlate some fundamental atomic quantities, such as the electron-electron repulsion energy and the peak height of Compton profile, in a simple manner. 相似文献
19.
《Journal of molecular catalysis. A, Chemical》1998,128(1-3):5-28
Addition of [Li2(THF)4][C(NPh)3] (2) to a THF solution of Cp*ZrCl3 (Cp*=C5Me5) yields, after recrystallization in Et2O, the zwitterionic species Cp*[C(NPh)3]ZrCl2Li(Et2O)(THF) (3). Treating 3 with excess methylaluminoxane (MAO) affords a homogeneous Ziegler–Natta catalyst for ethylene polymerization. Addition of LiNPh2 to 3 allows for Cl substitution to give the new product Cp*[C(NPh)3]Zr(NPh2)ClLi(THF)2 (4). A single crystal diffraction study of 4 reveals that the [C(NPh)3] ligand is η2-bound. The group 5 complex Cp*[C(NPh)3]TaMe2 (5) was prepared by addition of 2 to Cp*TaMe2Cl(OSO3CF3). The X-ray diffraction structure of 5 shows that the [C(NPh)3] ligand is η2-bound to tantalum and that, when compared to 4, there is less electron delocalization across the inner core of [C(NPh)3]. 相似文献
20.
R. M. Mehra A. Ganjoo Gurinder P. C. Mathur 《Journal of Thermal Analysis and Calorimetry》1995,45(3):405-415
The effect of In impurity on the crystallization kinetics and the changes taking place in the structure of (Se7Te3) have been studied by DTA measurements at different heating rates (α=5 deg·min?1, 10 deg·min?1, 15 deg·min?1 and 20 deg·min?1). From the heating rate dependence of the values ofT g,T c andT p, the glass transition activation energy (E t) and the crystallization activation energy (E c) have been obtained for different compositions of (Se7Te3)100?xInx (0≤×≤20). The variation of viscosity as a function of temperature has been evaluated using Vogel-Tamman-Fulcher equation. The crystallization data are analysed using Kissinger's and Matusita's approach for nonisothermic crystallization. It has been found that for samples containing In=0, 10, 15, 20 at%, three dimensional nucleation is predominant whereas for samples containing In=5 at%, two dimensional nucleation is the dominant mechanism. The compositional dependence ofT g and crystallization kinetics are discussed in terms of the modification of the structure of the Se?Te system. 相似文献