Partial oxidation of methane over Rh/supported-ceria catalysts: Effect of catalyst reducibility and redox cycles

Partial oxidation of methane (POM) was studied over Rh/(Ce_0.56Zr_0.44)O_2−x, Rh/(Ce_0.91Gd_0.09)O_2−x, Rh/(Ce_0.71Gd_0.29)O_2−x and Rh/(Ce_0.88La_0.12)O_2−x. The effect of catalyst reducibility and redox cycles was investigated. It was found that the type of doped-ceria support and its reducibility played an important role in catalyst activity. It was also observed that redox cycles had a positive influence on H₂ production, which was enhanced as the number of redox cycle increased. Results of carbon formation are discussed as a function of ionic conductivity. Temperature programmed reduction (TPR) profiles, BET surface area, ionic conductivity and XRD patterns were determined to characterize catalysts. Catalytic tests revealed that of the materials tested, Rh/(Ce_0.56Zr_0.44)O_2−x was the most active material for the production of syngas, which correlates with its TPR profile. It was observed that doping CeO₂ with Zr, rather than with La or Gd caused an enhanced reducibility of Rh/supported-ceria catalysts.     

A calorimetric examination of coal surfaces

This communication reports the results of some exploratory experiments to examine the surface of coal by (i) flow microcalorimetry (FM) and (ii) vapour sorption calorimetry (VSC). Excepting differential scanning calorimetry, calorimetric methods have not been widely-exploited in coal structure research. The intent of this short communication is to demonstrate that hitherto neglected calorimetric methods are very rewarding when applied to the study of coal surfaces.     

Asphyxial death caused by a laryngeal schwannoma: a case report

Neurogenic tumours of the larynx are unusual, with approximately 115 cases reported in the literature to date. Most of these lesions are benign, solitary submucosal nodules which present with hoarseness and are amenable to surgical resection. We present a case of a large pedunculated schwannoma arising in the aryepiglottic fold associated with sudden asphyxial death in an otherwise healthy young female.     

Cancer conferences. Can they be improved?

In a previous study, we showed that overexpression of cyclin D, a G1 cyclin, is frequently associated with keratinocyte carcinogenesis as an early event. Another G1 cyclin, cyclin E, was recently suggested to be a prognostic marker for breast cancer. In order to evaluate the role of cyclin E in human keratinocyte carcinogenesis, we analysed the expression of cyclin E by immunohistochemistry in normal skin, seborrheic keratosis (SK), keratoacanthoma (KA), actinic keratosis (AK), Bowen's disease (BD), basal cell carcinoma (BCC) and squamous cell carcinoma (SCC). Positive cells were seen rarely in normal epidermis, in 9 of 20 cases of SK, in 5 of 6 cases of KA, in 9 of 13 cases of AK and in all 27 cases of BD. Some of the cases of AK and BD had positive cells in the superficial epidermis, where atypicality is less obvious. In contrast, positive cells were seen in 4 of 25 cases of SCC and none of 15 cases of BCC. These results suggest that expression of cyclin E plays a role in the formation of benign and premalignant keratinocytic tumors, whereas down-regulation of cyclin E expression may be involved in carcinogenesis in human keratinocytes.     

T helper 2-dominant antilymphoma immune response is associated with fatal outcome

The precise role of the endogenous immune system in modulating cancer development remains unclear. Tumor cells are generally thought to be nonimmunogenic because they are of 'self' origin. However, tumor-reactive lymphocytes can be isolated from patients with many types of cancer. It is unclear what role these lymphocytes play and why they fail to protect the host. Using a murine B-cell leukemia/lymphoma (BCL1) model, we showed the development of a vigorous antitumor T-cell response in the tumor-susceptible host. Specific T-cell responses against BCL1 developed as early as day 4. However, the nature of this nonprotective response is different from the protective response produced in a major histocompatibility complex-matched tumor-resistant host. Susceptible hosts developed a T helper 2 (Th2)-dominant response, whereas resistant hosts developed a Th1-dominant response to BCL1. Cytolytic activity against BCL1 developed in both resistant and susceptible hosts, but in the susceptible host, this response was weaker and delayed compared with that in the resistant host. Thus, tumor susceptibility does not necessarily mean the absence of an antitumor immune response. Rather, the nature of the antitumor immune response is critical in determining clinical outcome.     

Children's deliberateness of planning according to task circumstances.

89 children ages 4 to 9 solved mazes varying in the presumed appropriateness of advance or improvisational planning. Using a between-Ss design, children's performance was compared in a standard condition that stressed accuracy in problem solving (designed to increase the importance of advance planning to avoid errors) and a variation stressing speed (designed to favor improvisational planning). Performance was compared by varying maze structure in terms of whether errors in route choices could be identified from a search of a small portion of the maze (favoring improvisation) or from a search through the entire maze (favoring advance planning). Children's planning strategies were stable over trials and had predictable effects on error rates. Children's usage of deliberate planning strategies was related to the circumstances of the problem, with more advanced planning when the structure of the mazes and instructions favored that strategy. Children used less advance planning when speed was a consideration and when the maze structure allowed avoidance of errors without extensive search. Results show that children's planning strategies are adapted to circumstances, and suggest that older children may be more proficient in this adaptation than are younger children. (PsycINFO Database Record (c) 2010 APA, all rights reserved)