Search

The highly strained bowl-shaped pentacyclic structure of herquline A has rendered it one of the most difficult problems in organic synthesis yet to be solved. The challenges associated with the synthesis of herquline A have been well documented in four Ph.D. dissertations and in multiple reports regarding syntheses of its structurally simpler congeners. Herein, we report the construction of the pentacyclic core of herquline A that contains both N10-C2 and C3-C3' bonds. The key for success was the development of the tandem aza-Michael addition/enolate capture protocol that set the stage for subsequent palladium catalyzed C3(sp2 )-C3'(sp2 ) coupling reaction. Ensuing oxidative dearomatization of the left aryl ring allowed the formation of the pentacyclic diketone core of herquline A.

Herein, we present the synthesis of 1-hydroxyherquline A and describe its reactivity discovered during its attempted conversion to herquline A, a long-sought natural product target in the synthetic chemical community. The strategic installation of the C1 hydroxyl group enabled the key

Carbon Capture and Sequestration (CCS) technology to slow global warming is a challenge to be solved worldwide. In this study, a dual circulating fluidized bed process using a solid-sorbent was developed for the post-combustion CO2 capture process from a pulverized coal power plant. This solid-sorbent-based CO2 capture process consists of absorber, regenerator, and standpipes in between them. An amine-functionalized silica was utilized as a solid-sorbent, and a bench-scale facility capable of treating flue gas of 20 Nm3/hr was constructed for the performance verification. As a result, when the sorbent to CO2 ratio was 24.6 wt/wt%, a CO2 capture efficiency of 80% or more was obtained, and the maximum CO2 working capacity was 4.5 wt%. A long-term stability was verified in the bench-scale facility and, as a result, the sorption capacity decreased by 5% for about 800 cycles. In addition, a solid-solid indirect heat exchanger was applied at the upper part of the absorber to partially recover solid sensible energy to reduce the regeneration energy. The sorbent loading inside the tube affects the heat transfer efficiency, and the heat transfer coefficient ranges from 8 to 10.5 W/m2-K.

Protein ubiquitination has a significant influence on diverse aspects of neuronal development and function. Dorfin, also known as Rnf19a, is a RING finger E3 ubiquitin ligase implicated in amyotrophic lateral sclerosis and Parkinson’s disease, but its in vivo functions have not been explored. We report here that Dorfin is a novel binding partner of the excitatory postsynaptic scaffolding protein PSD-95. Dorfin-mutant (Dorfin−/−) mice show reduced adult neurogenesis and enhanced long-term potentiation in the hippocampal dentate gyrus, but normal long-term potentiation in the CA1 region. Behaviorally, Dorfin−/− mice show impaired contextual fear conditioning, but normal levels of cued fear conditioning, fear extinction, spatial learning and memory, object recognition memory, spatial working memory and pattern separation. Using a proteomic approach, we also identify a number of proteins whose ubiquitination levels are decreased in the Dorfin−/− brain. These results suggest that Dorfin may regulate adult neurogenesis, synaptic plasticity and contextual fear memory.

To handle the extreme situation that must manage positional information of a very large volume, at least millions, of moving objects, a cluster-based scalable distributed computing system architecture, called the GALIS, which consists of multiple data processors, each dedicated to keeping records relevant to a different geographical zone and a different time zone, was proposed. In this paper, we propose a valid time management and time-zone shifting scheme, which are essential in realizing the long-term location data subsystem of GALIS, but missed in our previous prototype development. We explain how to manage valid time of moving objects to avoid ambiguity of location information. We also describe time-zone shifting algorithm, with three variations, such as RT-TZS, B-TZS and TPB-TZS. Through experiments related with query processing time and CPU utilization, we show the efficiency of the proposed time-zone shifting schemes.

Recently, the web sites such as e-business sites and shopping mall sites deal with lots of image information. To find a specific image from these image sources, we usually use web search engines or image database engines which rely on keyword only retrievals or color based retrievals with limited search capabilities. This paper presents an intelligent web image retrieval system. We propose the system architecture, the texture and color based image classification and indexing techniques, and representation schemes of user usage patterns. The query can be given by providing keywords, by selecting one or more sample texture patterns, by assigning color values within positional color blocks, or by combining some or all of these factors. The system keeps track of user's preferences by generating user query logs and automatically add more search information to subsequent user queries. To show the usefulness of the proposed system, some experimental results showing recall and precision are also explained.