Quantitative analysis of degree of substitution/molar substitution of etherified polysaccharide derivatives.

Due to the unique properties such as nontoxicity, biodegradability, availability from renewable resources, and cost-effectiveness, polysaccharides play a very important part in the science and technology field. The various chemically modified derivatives of these offer a wide range of high value-added in both food and non-food industries. Among the chemical modification, etherified polysaccharide is one of the most widespread derivatives by introducing an ether group which is commonly stable in both acidic and alkaline conditions. Hydroxyalkylation, alkylation, carboxymethylation, cationization, and cyanoethylation are some of the modifications commonly employed to prepare polysaccharides ethers derivatives. There also has been a growing tendency for creating new types of modification by combining the different means of chemical techniques. The correct determination of degree of substitution (DS)/molar substitution (MS) is crucially important. The objective of this article is to summarize developments in synthetic etherified polysaccharides, involving analytical methods for determination of MS/DS, measurement processes, and the associated mechanisms.

B-periodic oscillations in the Hall-resistance induced by a dc-current-bias under combined microwave-excitation and dc-current bias in the GaAs/AlGaAs 2D system.

We report the observation of dc-current-bias-induced B-periodic Hall resistance oscillations and Hall plateaus in the GaAs/AlGaAs 2D system under combined microwave radiation- and dc bias excitation at liquid helium temperatures. The Hall resistance oscillations and plateaus appear together with concomitant oscillations also in the diagonal magnetoresistance. The periods of Hall and diagonal resistance oscillations are nearly identical, and source power (P) dependent measurements demonstrate sub-linear relationship of the oscillation amplitude with P over the span 0 < P ≤ 20 mW.

Semi-metals as potential thermoelectric materials.

The best thermoelectric materials are believed to be heavily doped semiconductors. The presence of a band gap is assumed to be essential to achieve large thermoelectric power factor and figure of merit. In this work, we propose semi-metals with large asymmetry between conduction and valence bands as an alternative class of thermoelectric materials. To illustrate the idea, we study semi-metallic HgTe in details experimentally and theoretically. We employ ab initio calculations with hybrid exchange-correlation functional to accurately describe the electronic band structure in conjunction with the Boltzmann Transport theory to investigate the electronic transport properties. We calculate the lattice thermal conductivity using first principles calculations and evaluate the overall figure of merit. To validate our theoretical approach, we prepare semi-metallic HgTe samples and characterize their transport properties. Our first-principles calculations agree well with the experimental data. We show that intrinsic HgTe, a semimetal with large disparity in its electron and hole masses, has a high thermoelectric power factor that is comparable to the best known thermoelectric materials. Finally, we propose other possible materials with similar band structures as potential candidates for thermoelectric applications.

Comparative study of microwave radiation-induced magnetoresistive oscillations induced by circularly- and linearly- polarized photo-excitation.

A comparative study of the radiation-induced magnetoresistance oscillations in the high mobility GaAs/AlGaAs heterostructure two dimensional electron system (2DES) under linearly- and circularly- polarized microwave excitation indicates a profound difference in the response observed upon rotating the microwave launcher for the two cases, although circularly polarized microwave radiation induced magnetoresistance oscillations observed at low magnetic fields are similar to the oscillations observed with linearly polarized radiation. For the linearly polarized radiation, the magnetoresistive response is a strong sinusoidal function of the launcher rotation (or linear polarization) angle, θ. For circularly polarized radiation, the oscillatory magnetoresistive response is hardly sensitive to θ.

Long-term outcome of transcatheter arterial chemoembolization after radiofrequency ablation as a combined therapy for Chinese patients with hepatocellular carcinoma.

OBJECTIVE: This study was undertaken to assess the long-term outcome of transcatheter arterial chemoembolization (TACE) after radiofrequency ablation (RFA) combined with a combined therapy for Chinese patients with intermediate (stage B) hepatocellular carcinoma (HCC) of single block type, and evaluate the survival rate for 1, 3, 5, and 7 years. RESEARCH DESIGN AND METHODS: This prospective, single-center study consisted of patients with solitary massive intermediate (stage B) HCC treated by RFA combined with TACE from October 1999 to December 2013. MAIN OUTCOME MEASURES: The survival rate of the patients for 1, 3, 5, and 7 years, and safety of the RFA treatment in the interim, total RFA for each case, and number of TACE cycles were evaluated. RESULTS: Ninety-three patients (aged 54.4 ± 8.0 years) underwent RFA combined with TACE as a combined therapy, and they were analyzed and followed up until December 2013. The mean time for the initial ablation was 1.5-3 h, and, on average, each patient received 1.39 RFA and 1.43 TACE therapies. Overall, complete ablation was achieved in nine patients, and the majority of ablation was seen in 84 patients. The longest survival time was 102 months and, among the survivors the 1, 3, 5, and 7 year survival rate was 94.4%, 52.3%, 26.1%, and 14.1%, respectively. The median survival time was 36 months (95% confidence interval = 32.7-39.3). Serum alpha-fetoprotein (AFP) levels showed significant correlation with tumor size in patients with HCC (r = 0.323, p = 0.0001). There were no major complications related to this therapy. CONCLUSION: This was the first study that performed RFA combined with TACE in Chinese patients with intermediate (stage B) HCC. RFA combined with TACE, as a combined therapy for intermediate (stage B) HCC, seems to be a promising regimen that showed a satisfactory clinical effect, which may become a new therapy mode for HCC. However, a larger cohort and control group(s) reflecting usual standards of care are needed to assess the external validity of these results in a wider population.

Transcatheter arterial chemoembolization combined with interferon-α is safe and effective for patients with hepatocellular carcinoma after curative resection.

OBJECTIVES: Intrahepatic recurrence is the major cause of death among patients with hepatitis B virus (HBV)- related hepatocellular carcinoma (HCC) after curative surgical resection. Several approaches have been reported to decrease the recurrence rate. The objective of our study was to compare the clinical effects of transcatheter arterial chemoembolization (TACE) combined with interferon-alpha (IFN-α) therapy on recurrence after hepatic resection in patients with HBV-related HCC with that of TACE chemotherapy alone. METHODS: We retrospectively analyzed the data from 228 patients who were diagnosed with HBV-related HCC and underwent curative resection between January 2001 to December 2008. The patients were divided into TACE (n = 126) and TACE-IFN-α (n = 102) groups for postoperative chemotherapy. The TACE regimen consisted of 5-fluorouracil (5-FU), cisplatin (DDP) , and the emulsion mixed with mitomycin C (MMC) and lipiodol. The recurrence rates, disease-free survival (DFS), overall survival (OS), and risk of recurrence were evaluated. RESULTS: The clinicopathological parameters and adverse effects were similar between the 2 groups (P > 0.05). The median OS for the TACE- IFN-α group (36.3 months) was significantly longer than that of the TACE group (24.5 months, P < 0.05). The 3-and 5-year OS for the TACE-IFN-α group were significantly longer than those of the TACE group (P < 0.05) and the recurrence rate was significantly lower (P < 0.05). The TACE and IFN-α combination therapy, active hepatitis HBV infection, the number of tumor nodules, microvascular invasion, liver cirrhosis, and the BCLC stage were independent predictors of OS and DFS. CONCLUSIONS: The use of the TACE and IFN-α combination chemotherapy after curative hepatic resection safely and effectively improves OS and decreases recurrence in patients with HBV-related HCC who are at high risk. Our findings can serve as a guide for the selection of postoperative adjuvant chemotherapy for patients with HBV-related HCC who are at high risk of recurrence.