O/W Emulsions with Liquid Crystals as Vehicles of β-Escin

Aescin is an important active substance composed of saponin glucosides topical employed in the treatment of inflammatory and edematous conditions. A particular kind of skin care product called α-gel lamellar phases emulsion was developed, containing β-escin. Detailed knowledge of the lamellar phases behavior has been obtained by DSC, rheological measurements and polarized-light optical microscopy. Moreover the effects of lamellar phases on β-escin release profiles have been studied.     

Characterization and coordination of intercalation - Non-intercalation phase transition in a new hybrid halide perovskite (n-C16H33NH3)2 ZnCl4

The ac conductivity σ(ω,T) and the complex dielectric permittivity ε^•(ω,T) as function of temperature 100 K < T < 400 K and frequency in the range 1 kHz ≤ f ≤ 100 kHz, as well as some thermal characterizations, namely the differential scanning calorimetry (DSC) and the differential thermal analysis (DTA) thermograms, were, measured and presented for polycrystalline virgin samples of the titled compound. It is one member of the long-chain of Zn hybrids of the series (n-C_nH_2n+1NH₃)₂ZnCl₄ (n = 8–18) and hence it belongs to the class of thermal energy storage materials.Our data evidenced that the hybrid undergoes a first order solid-solid structural phase transition from an intercalation to a non-intercalation at ≈373 K which is associated with an increase in the interlayer spacing “d” by 19.3%. In the room temperature phase, the hybrid is intercalated and tends to crystallize in an isolated square tetrahedra of zero-dimensional (0D) but arranged in the crystal system in two-dimensional (2D) via the assisted charge hydrogen bonds NH…Cl. It is therefore highly packed and hence have a highly transition temperature, highly thermal energy storage compared with other hybrids of the same n but of different M. These novelties characteristics suggested that the hybrid is more suitable for solar energy research. The even-odd effect, which is only common for Zn and Co in the room temperature phase and absent for other compounds, as well as the mechanism of the phase change have been discussed. The role of the coordination of the divalent metal ion and the dimensionality of the isolated unit (MCl₄)⁻² (M = Zn and/or Co) are considered. Comparison of the current phase transition with that of Zn compounds (n = 8, 10, 12, and 14) has been given.     

细菌生长的热动力学研究

用热活性检测系统测定了5种弧菌在相同培养基下生长的热谱,并在不同温度下对指数生长期的热谱进行了处理,得到有关菌种的生长速率常数和激活能;在此基础上,按化学动力学过渡态理论计算,得到有关热力学函数。     

热活性检测器性能测试及细菌热谱图的测定

介绍了２２７７——热活性检测器测量原理及应用范围，对该仪器的各项性能进行了测试，并用该仪器测定了１０种细菌代谢热谱图。     

细菌生长的热谱图测定和生长速率的研究

用微量热计测定了8种细菌在相同培养基下代谢完整的热谱曲线,并对几个温度下在指数生长期的热谱图进行了动力学处理,得出不同了温度下细菌生长的速率常数和激活能。这些数据为药物对细菌的抑制作用提供了科学依据。     

Effect of akyl-γ-cyclodextrins on the stability of retinol

Inclusion complexation between retinol (RET) and two synthetic alkyl carbonates of γ-cyclodextrin (alkyl-γ-CD) derivatives, ethyl-γ-cyclodextrin (E-CD) and octyl-γ-cyclodextrin (O-CD), was investigated by means of different techniques. The complexes were characterized by differential scanning calorimetry (DSC). Phase solubility studies, according to the method of Higuchi and Connors [1] were used to evaluate the complexation in aqueous solution at room temperature. In the present study inclusion complexes of retinol with E-CD and with O-CD were prepared to prevent its rapid degradation. In order to investigate the behavior of retinol under UV light, test of irradiation was performed separately on samples prepared dispersing retinol (0.1% w/w) or an equivalent amount of retinol/alkyl-γ-CD respectively in hydroxyethylcellulose (HEC) gel and in an O/W emulsion. The stability over time of retinol was also investigated storing the samples at 40 °C. Moreover retinol permeation through porcine skin has been evaluated employing Franz cells [2]. Retinol solubility was increased in presence of cyclodextrins while DSC analysis suggest that this inclusion agents are able to interact with retinol. Data for skin accumulation in porcine ear skin showed that alkyl-CDs increase of approximatively 1,5-fold retinol skin accumulation. Studies on the stability showed that both the inclusion complexes considered are able to increase retinol stability to light exposure and also to heat.     

Measurements of the isochoric heat capacity,the critical point (TC, ρC) and vapor–liquid coexistence curve (TS, ρS) of high-purity toluene near the critical point

Isochoric heat capacities (C_V, V, T), phase boundary properties (T_S, ρ_S) and the critical (T_C, ρ_C) parameters for high-purity (0.9999+ mole fraction) toluene have been measured with a high temperature, high pressure, nearly constant volume adiabatic calorimeter and quasi-static thermogram technique. Measurements were made at three selected liquid and vapor isochores 777.8, 555.25, and 214.64 kg m⁻³ in the temperature range from 379 to 591 K. For five near-critical isochores 268.68, 281.68, 296.62, 301.52, and 318.28 kg m⁻³, the measurements were made in the immediate vicinity of the coexistence curve in order to accurately determine the phase transition temperatures (T_S, ρ_S) (shape of the coexistence curve near the critical point) and the critical parameters (T_C, ρ_C). The total combined uncertainty of heat capacity, density, and temperature measurements were estimated to be less than 2%, 0.06%, and 15 mK, respectively. The uncertainties reported in this paper are expanded uncertainties at the 95% confidence level with a coverage factor of k = 2. The uncertainty of the phase transition and the critical temperature value was 0.02 K. The Krichevskii parameter for some toluene-containing binary mixtures was calculated. The derived values of the Krichevskii parameter were used to estimate the effect of dilute impurities on the critical parameters of toluene. The measured values of saturated density near the critical point were interpreted in terms of the “complete scaling” theory in order to study singularity behavior of the coexistence curve diameter. The measured isochoric heat capacities and saturated densities were compared with the data reported by other authors and values calculated from an equation of state and other correlations.