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51.
Polymeric lipid nanoparticles were prepared in 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid buffer (pH 8.0, 10 mM) by
taking advantage of salt bridges formed between poly(N-isopropylacrylamide-co-methacrylic acid) (P(NIPAM-co-MAA)) and N-[3-(dimethylamino)propyl]-octadecanamide (DMAPODA). The homogeneous nanoparticles of 200–250 nm were obtained when the copolymer
was included in the preparation so that the relative mass of copolymer to lipid was more than 5. However, when the relative
amount of copolymer was less than 5, large agglomerates more than 10 μm were observed together with nanoparticles. The protonated
amino groups of DMAPODA will attach to the ionized carboxyl groups of P(NIPAM-co-MAA), and they would act as polymeric amphiphiles.
It is believed that the hydrophilic copolymer can stabilize the hydrophobic core of the lipid. The critical association concentrations
were determined to be 32, 112, and 158 mg/l, when the lipid/copolymer ratios were 1:5, 1:23, and 1:50, respectively. 相似文献
52.
Axel Bacher 《Journal of Combinatorial Theory, Series A》2011,118(8):2365-2391
We define a new family of self-avoiding walks (SAW) on the square lattice, called weakly directed walks. These walks have a simple characterization in terms of the irreducible bridges that compose them. We determine their generating function. This series has a complex singularity structure and in particular, is not D-finite. The growth constant is approximately 2.54 and is thus larger than that of all natural families of SAW enumerated so far (but smaller than that of general SAW, which is about 2.64). We also prove that the end-to-end distance of weakly directed walks grows linearly. Finally, we study a diagonal variant of this model. 相似文献
53.
Kurt Dehnicke 《无机化学与普通化学杂志》2003,629(5):729-743
A compilation is given on new syntheses, properties, and structures of complexes with M≡N—E ? M=N=E nitrido bridges with transition metal nitrogen multiple bonds and participation of the main group elements E of phosporus, sulfur, and chlorine. 1. MNP: This atomic sequence is realized in phosphoraneiminato complexes with transition metals in high oxidation states and termal bond of the (NPR3—) ligand. A series of new complexes of this type is reported with M = zirconium, hafnium, molybdenum, tungsten, and rhenium, among these the homoleptic species [Hf(NPPh3)4] and [M(NPPh3)4]2+ with M = Mo and W. Therefrom the isolobal complexes [:N≡Mo(NPPh3)3], [:O≡W(NPPh3)3]+, [(O)2Mo(NPPh3)2], and [(O)3Re(NPPh3)] are derived. 2. MNS: Adding to compounds with this atomic sequence, new complexes were developed on the basis of the functional ligand groups thionitrosyl ( a ), dinitridosulphate(II) ( b ), dinitridosulphate(IV) ( c ), and cyclothiazeno ( d ) (cyclo‐3, 5‐dithia‐2, 4, 6‐triazino):
54.
Electromotive forces (emf) were measured in the transference cells: AgAgCl- Nacl (m2) in Z NaCl (m1) in ZAgClAg and NaxHg1-xNaCl (m1) in Z NaCl (m2) in ZNaxHg1-x (where NaxHg1-x denotes a flowing Na–amalgam electrode and Z an aqueous-organic solvent mixture) at various molalities m
2 > m1 of NaCl in Z = (ethylene glycol + water), (acetonitrile + water) and (1,4-dioxane + water), with mass fractions of the organic components 0.8. The transference number of Na+ in (ethylene glycol + water) and (1,4-dioxane + water) varies little with respect to that in pure water medium, whereas in (acetonitrile + water) it increases remarkably with increasing proportion of acetonitrile so as to approach equitransference, behavior similar to that previously found in (methanol + water) and in (ethanol + water). At acetonitrile mass fraction 0.6 NaCl is sufficiently close to equitransference to emerge as a useful salt bridge, nearly at the same level as the popular aqueous KCl. 相似文献
55.
The reactions of Cp*M(PMe3)Cl2 (M = Rh ( 1a ), Ir ( 1b )) with (NEt4)2[WS4] led to the heterodimetallic sulfido‐bridged complexes Cp*M(PMe3)[(μ‐S)2WS2] (M = Rh ( 2a ), Ir ( 2b )), whereas the dimers [Cp*MCl(μ‐Cl)]2 (M = Rh ( 4a ), Ir ( 4b )) reacted with (NEt4)2[WS4) to give the known trinuclear compounds [Cp*M(Cl)]2(μ‐WS4) (M = Rh ( 5a ), Ir ( 5b )). Hydrolysis of the terminal W=S bonds converts 2a, b into Cp*M(PMe3)[(μ‐S)2WO2] (M = Rh ( 3a ), Ir ( 3b )). Salts of a heterodimetallic anion, A[CpMo(I)(NO)(WS4)] ( 6 ) (A+ = NEt4+, NPh4+) were obtained by reactions of [CpMo(NO)I2]2 with tetrathiotungstates, A2[WS4]. The complexes were characterized by IR and NMR (1H, 13C, 31P) spectroscopy, and the X‐ray crystallographic structure of Cp*Rh(PMe3)[(μ‐S)2WS2] ( 2a ) has been determined. The bond lengths and angles in the coordinations spheres of Rh and W in 2a (Rh···W 288.5(1) pm) are compared with related complexes containing terminal [WS42—] chelate ligands. 相似文献
56.
Synthesis of a Functional Aluminium Alkynide, Me3C‐C≡C‐AlBr2, and its Reactions with the Bulky Lithium Compound LiCH(SiMe3)2 Treatment of aluminium tribromide with the lithium alkynide (Li)C≡C‐CMe3 afforded the aluminium alkynide Me3C‐C≡C‐AlBr2 ( 1 ) in an almost quantitative yield. 1 crystallizes with trimeric formula units possessing Al3C3 heterocycles and the anionic carbon atoms of the alkynido groups in the bridging positions. A dynamic equilibrium was determined in solution which probably comprises trimeric and dimeric formula units. Reaction of 1 with one equivalent of LiCH(SiMe3)2 yielded the compound [Me3C‐C≡C‐Al(Br)‐CH(SiMe3)2]2 ( 2 ), which is a dimer via Al‐C‐Al bridges. Two equivalents of the lithium compound gave a mixture of four main‐products, which could be identified as 2 , Li[Me3C‐C≡C‐Al{CH(SiMe3)2}3] ( 3 ), Me3C‐C≡C‐Al[CH(SiMe3)2]2 ( 4 ), and Al[CH(SiMe3)2]3. The lithium atom of 3 is coordinated by the C≡C triple bond and an inner carbon atom of one bis(trimethylsilyl)methyl group. Further interactions were observed to C‐H bonds of methyl groups. 相似文献
57.
Georg Reinhard Michael Knorr Pierre Braunstein Ulrich Schubert Saeed Khan Charles E. Strouse Herbert D. Kaesz Alfred Zinn 《欧洲无机化学杂志》1993,126(1):17-21
Transition Metal Silyl Complexes, 44. — Preparation of the Binuclear Silyl Complexes (CO)3(R3Si)Fe(μ-PR′R′′)Pt(PPh3)2 by Oxidative Addition of (CO)3(R′R′′HP)Fe(H)SiR3 to (C2H4)Pt(PPh3)2 The complexes (CO)3(R′R′′HP)Fe(H)SiR3 ( 1 ) [PHR′R′′ = PHPh2, PH2Ph, PH2Cy; SiR3 = SiPh3, SiPh2Me, SiPhMe2, Si(OMe)3] react with Pt(C2H4)(PPh3)2 to give the dinuclear, silyl-substituted complexes (CO)3(R3Si)Fe(μ-PR′R′′)Pt(PPh3)2 ( 2 ) in high yields. Upon reaction of 2 (R = R′ R′′ = Ph) with CO, the PPh3 ligand at Pt being trans to the PPh2 bridge is exchanged, and (CO)3(Ph3Si)Fe(μ-PPh2)Pt(PPh3)CO ( 3 ) is formed. Complex 3 is characterized by an X-ray structure analysis. The rather short Fe — Si distance [233.9(2) pm] and the infrared spectrum of 3 indicate that the Fe — Pt bond is quite polar. 相似文献
58.
Douglas X. West Jerry P. Jasinski John M. Jasinski Ray J. Butcher 《Journal of chemical crystallography》1999,29(10):1089-1095
Structures of two binuclear copper(II) complexes with sulfato bridges and tridentate 2-acetylpyridine 3-azacyclothiosemicarbazone ligands have been solved. The complex-sulfato-bis{(2-acetylpyridine 3-hexamethyleneiminyl-thiosemicarbazonato)copper(II)} N,N-dimethylformamide, [Cu(Achexim)]2SO4·DMF, has the following structural properties: triclinic, P1¯(#2), a = 12.314(4), b = 15.885(4), c = 10.959(4) Å, = 103.25(2), = 103.60(2), = 109.94(2)°, V = 1843(2) Å3, and Z = 2; for -sulfato-bis{(2-acetylpyridine 3-piperidylthiosemicarbazonato)copper(II)}chloroform, [Cu(Acpip)]2SO4·CHCl3: triclinic, P1¯(#2), a = 11.657(1), b = 17.101(2), c = 10.338(1) Å, = 98.51(1), = 109.294(7), = 107.016(9)°, V = 1790.3(4) Å3, and Z = 2. The size of the azacyclo ring significantly affects the stereochemistry of these binuclear complexes. 相似文献
59.
Summary First we give a construction of bridges derived from a general Markov process using only its transition densities. We give sufficient conditions for their existence and uniqueness (in law). Then we prove that the law of the radial part of the bridge with endpoints zero derived from a special multidimensional Ornstein--Uhlenbeck process equals the law of the bridge with endpoints zero derived from the radial part of the same Ornstein--Uhlenbeck process. We also construct bridges derived from general multidimensional Ornstein--Uhlenbeck processes. 相似文献
60.
Harald Schfer 《Angewandte Chemie (International ed. in English)》1976,15(12):713-727
The chemistry of the gaseous halide complexes which have been observed in large numbers in recent years is discussed for the example of chlorides. Homo-complexes—dimeric or polymeric chloride molecules containing chlorine-bridge linkages [e.g.(NaCl)n, n = 2—4; (CuCl)n, n = 2—5; (BeCl2)n, n = 2—4; Pd6Cl12]—occur through broad areas of the Periodic Table. Comparison of the dissociation enthalpy of such molecules with the vaporization enthalpy of the liquid chlorides is particularly informative. Hetero-complexes are formed from different chloride molecules by linkage through Cl bridges. Not only 1:1 complexes (e.g. NaAlCl4, TIPbCl3, KThCl5, CdPbCl4, AlUCl8) but also larger molecules (e.g. CoAl2Cl8, CrAl3Cl12, Cu2UCl6, In2UCl10) are known. Types of formulas, structures, and above all the formation enthalpies of such complexes are discussed critically. Hetero-complexes are useful in chemical transport reactions, as aids in syntheses, and in gas-chromatographic separations (lanthanoids, actinoids). They also play a part in many industrial processes (chlorination of ores) and in recently developed types of high-pressure discharge tubes. 相似文献