Crystalline Morphology and Nonisothermal Crystallization Behaviors of iPP/PcBR Blends

Isotactic polypropylene/poly(cis‐butadiene) rubber (iPP/PcBR) blends were prepared by melt mixing. The influence of PcBR content on crystalline morphology and nonisothermal crystallization behaviors of iPP was investigated by polarized optical microscopy (POM), small angle light scattering (SALS), and differential scanning calorimetry (DSC). The POM showed that an increase of PcBR ranging from 10 vol% to 40 vol% led to less perfection of spherulites, vaguer boundaries between spherulites, and smaller spherulite size, which was quantitatively validated by SALS. The presence of PcBR also remarkably affected the nonisothermal crystallization behaviors of iPP. An addition of PcBR caused higher crystallization peak temperature and a faster crystallization rate, meaning a heterogeneous nucleation effect of PcBR upon crystallization of iPP. For the same sample, the crystallization peak temperature moved to lower temperature and the crystallization rate increased as the cooling rate increased. The Ozawa and combined Avrami and Ozawa equations were used to describe the nonisothermal crystallization process of iPP and blends. The combined Avrami and Ozawa equation was more appropriate for the crystallization of the blends. Crystallization activation energy of iPP and blends was calculated by the Kissinger equation; the result showed that crystallization activation energy decreased as the content of PcBR increased from 30 vol% to 40 vol%.     

Variations in the Concentrations of Cu and Zn and in the Ratio of Cu to Zn in Whole Blood and Hair Samples from Hepatocellular Carcinoma Patients and from Healthy Controls in Taiwan

An atomic absorption spectrophotometer was used to determine concentrations of copper and zinc and the ratio of Cu to Zn in samples of whole blood and hair from hepatocellular carcinoma (HCC) patients (n=51) and from healthy controls (n=50) in Taiwan. Our results indicate that the HCC patients have higher copper concentrations and higher ratios of Cu to Zn than do the healthy controls both in whole blood and hair samples, but only the concentration of copper and the ratio of Cu to Zn in whole blood were significantly different (p<0.001 and p<0.05). Conversely, a lower concentration of zinc was found in whole blood and hair samples of HCC patients. Similarly, only the concentration of zinc in whole blood showed a significant difference (p<0.001). We concluded that the whole blood concentrations of copper and zinc and the ratio of Cu to Zn seemed to have a higher correlation with HCC. Thus, we suggest that a sample of whole blood may be a more suitable diagnostic sample than is a hair sample for HCC.     

Parotid perfusion in nasopharyngeal carcinoma patients in early-to-intermediate stage after low-dose intensity-modulated radiotherapy: Evaluated by fat-saturated dynamic contrast-enhanced magnetic resonance imaging

PurposeTo investigate parotid perfusion in early-to-intermediate stage after parotid-sparing radiation dose using fat-saturated DCE-MRI, and to verify whether the perfusion alteration was related to radiation dose and the PSV.Methods and MaterialsThirty-two parotid glands from 16 consecutive patients with pathologically proven nasopharyngeal carcinoma treated by IMRT were examined. The parotid glands received a radiation dose of 28.9 ± 3.9 Gy with a PSV of 43.1% ± 13.9%. Perfusion parameters were calculated using time-shifted Brix model from fat-saturated DCE-MRI data before (pre-RT) and in early-to-intermediate stage after (post-RT) IMRT. Paired t-test was used to evaluate perfusion changes, while Pearson's correlation test was used to examine perfusion dependency on radiation dose and PSV. For multiple comparisons Bonferroni correction was applied.ResultsSuccessful fat saturation was achieved in 29 of 32 parotid glands. Compared with pre-RT, the post-RT parotid glands showed significantly higher A, peak enhancement, and wash-in slope, plus a lower K_el, suggesting a mixed effect of increased vascular permeability and acinar loss. Linear regression showed that peak enhancement was positively associated with radiation dose in post-RT parotid glands. K_el and slope were negatively associated with PSV, while time-to-peak was positively associated with PSV significantly.ConclusionsOur results suggest that time-shifted Brix model is feasible for quantifying parotid perfusion using DCE-MRI. The perfusion alterations in early-to-intermediate stage after IMRT might be related to a mixed effect of increased vascular permeability and acinar loss with dose and PSV dependencies.     

PM10 formation during the combustion of N2-char and CO2-char of Chinese coals

The formation of PM₁₀ (particles less than or equal to 10 μm in aerodynamic diameter) during char combustion in both air-firing and oxy-firing was investigated. Three Chinese coals of different ranks (i.e., DT bituminous coal, CF lignite, and YQ anthracite) were devolatilized at 1300 °C in N₂ and CO₂ atmosphere, respectively, in a drop tube furnace (DTF). The resulting N₂-chars and CO₂-chars were burned at 1300 °C in both air-firing (O₂/N₂ = 21/79) and oxy-firing (O₂/CO₂ = 21/79). The effects of char properties and combustion conditions on PM₁₀ formation during char combustion were studied. It was found that the formation modes and particle size distribution of PM₁₀ from char combustion whether in air-firing or in oxy-firing were similar to those from pulverized coal combustion. The significant amounts of PM_0.5 (particles less than or equal to 0.5 μm in aerodynamic diameter) generated from combustion of various chars suggested that the mineral matter left in the chars after coal devolatilization still had great contributions to the formation of ultrafine particles even during the char combustion stage. The concentration of PM₁₀ from char combustion in oxy-firing was generally less than that in air-firing. The properties of the CO₂-chars were different from those of the N₂-chars, which was likely due to gasification reactions coal particles experienced during devolatilization in CO₂ atmosphere. Regardless of the combustion modes, PM₁₀ formation in combustion of N₂-char and CO₂-char from the same coal was found to be significantly dependent on char properties. The difference in the PM₁₀ formation behavior between the N₂-char and CO₂-char was coal-type dependent.     

Significant decrease in interfacial energy of grain boundary through serrated grain boundary transition

The mechanism of serrated grain boundary formation and its effect on liquation behaviour have been studied in a wrought nickel-based superalloy – Alloy 263. It was newly discovered that grain boundaries are considerably serrated in the absence of γ?′-phase or M₂₃C₆ at the grain boundaries. An electron energy-loss spectroscopy study suggests that serration is triggered by the discontinuous segregation of C and Cr atoms at grain boundaries for the purpose of relieving the excessive elastic strain energy. The grain boundaries serrate to have specific segments approaching one {111} low-index plane at a boundary so that the interfacial free energy of the grain boundary can be decreased, which may be responsible for the driving force of the serration. The serrated grain boundaries effectively suppress grain coarsening and are highly resistant to liquation due to their lower wettability resulting from a lower interfacial energy of the grain boundary.     

Two-Phase Closed-Loop Thermosyphon for Electronic Cooling

This study experimentally investigated the thermal performance of a two-phase closed-loop thermosyphon with a thermal resistance model for electronic cooling. The evaporator, rising tube, condenser, and falling tube, which are the four main devices, formed a closed-loop system with water as the working fluid. The experimental parameters were the evaporator surface type, fill ratio of working fluid, and input heating power. The results indicated that the evaporator and condenser thermal resistance decrease with increasing input heating power. The condenser thermal resistance clearly increased with increasing fill ratio. A groove-type evaporator surface with 0.2 mm height and 1 mm width had the best performance, decreasing the evaporator thermal resistance about 15.5% compared to a smooth surface. Correlations for evaporator and condenser thermal resistance were also developed, and their precisions, when compared with the experimental data, were about 9.6 and 11.6%, respectively. Because of the intermittent boiling mechanism at 47% fill ratio with input heating power from 60 to 80 W, the temperature showed obvious oscillations with the smooth evaporator surface.     

A study of design velocity field computation for shape optimal design

Design velocity field computation is an important step in computing shape design sensitivity coefficients and updating a finite element mesh in the shape design optimization process. Applying an inappropriate design velocity field for shape design sensitivity analysis and optimization will yield inaccurate sensitivity results or a distorted finite element mesh, and thus fail in achieving an optimal solution. In this paper, theoretical regularity and practical requirements of the design velocity field are discussed. The crucial step of using the design velocity field to update the finite element mesh in the design optimization process is emphasized. Available design velocity field computation methods in the literature are summarized and their applicability for shape design sensitivity analysis and optimization is discussed. Five examples are employed to discuss applicability of these methods. It was found that a combination of isoparametric mapping and boundary displacement methods is ideal for the design velocity field computation.     

Optimal growth and recursive utility: Phase diagram analysis

The dynamics of the one-sector optimal growth model with recursive utility is analyzed through the use of a phase diagram. The steady state uniquely exists and is a saddle point. An increase in recursivity lowers both the steady-state capital and steady-state consumption. The model differs from the constant discount rate model in that a reduction in the population growth rate or a Hicks-neutral technical progress increases the steady-state consumption but not necessarily the steady-state capital.This research was supported in part by Indiana University through an Outstanding Young Faculty Award for which the author is grateful.The author is particularly indebted to Robert Becker and John Boyd for a careful reading of and detailed comments on an earlier draft, and to Frank Raymond and an anonymous referee for suggesting various expositional improvements. He is also indebted to Roy Gardner, Nori Hashimoto, and Nicolas Spulber for their suggestions.     

产量──密度模型讨论

本文给出产量与密度函数关系     

HPLC法测定库克Noni果汁中游离态水溶性维生素

采用HPLC法测定Noni果汁中游离态的抗坏血酸（Vc）、硫胺素（VB1）和烟酰胺（VB5）,其测定条件为：色谱柱为Alhima C18柱,流动相为甲醇-0．01％磷酸（3：7,V／V）,流速为1．0mL／min,进样量为20μL,柱温为室温,采用二极管阵列检测器在251nm下检测。在上述色谱测定条件下三种维生素能得到良好分离。结果表明,该方法灵敏度高,定量准确,重现性好,回收率高。昕测Noni果汁中三种维生素的含量分别为：Vc0．354mg／mL,VB10．0663mg／mL,VB50．131mg／mL。说明Noni果汁中三种必需维生素含量丰富,可作为维生素缺乏的营养补充剂;所建立的测定方法可作为一种Noni果汁生产质量控制方法。