[structure: see text] Symmetrical and unsymmetrical 2',7'-dichlorofluorescein (DCF) derivatives have been synthesized by means of Mannich reactions and an aromatic Claisen rearrangement. NMR and fluorescence spectroscopic studies reveal the correlation between the conformations, the photoinduced electron transfer mechanism, and fluorescent intensities of these DCF derivatives. Two quenching nit...

In this paper, an improved analytical model for IEEE 802.11 distributed coordination function (DCF) under finite load is proposed by closely following the specifications given in IEEE 802.11 standard. The model is investigated in terms of channel throughput assuming perfect channels. It is shown that the proposed model gives better insight into the operation of DCF compared with the existing an...

Satellite observation scheduling plays a significant role in improving the efficiency of Earth systems. To solve large-scale multisatellite problem, this article proposes an ensemble metaheuristic and exact algorithms based on divide-and-conquer framework (EHE-DCF), including task allocation phase phase. In phase, each is allocated to proper orbit incorporated with probabilistic selection tabu ...

Leukemic cells incubated in vitro with 2'-deoxyadenosine (dAdo) plus an inhibitor of adenosine deaminase, 2'-deoxy-coformycin (DCF), show different metabolic responses depending on the histologic and immunologic type of the leukemia. Leukemic cells were obtained from 54 patients with acute lymphoblastic leukemia (ALL), 9 with myeloid or nonlymphoblastic leukemia, 3 with chronic lymphocytic leuk...

Distributed contention based Medium Access Control (MAC) protocols are the fundamental components for IEEE 802.11 based Wireless Local Area Networks (WLANs). Contention windows (CW) change dynamically to adapt to the current contention level: Upon each packet collision, a station doubles its CW to reduce further collision of packets. IEEE 802.11 Distributed Coordination Function (DCF) suffers f...

Over the past few years, Wireless Local Area Networks (WLANs) have gained an increased attention and a large number of WLANs are being deployed in universities, companies, airports etc. Majority of the IEEE 802.11 based WLANs employ Distributed Coordination Function (DCF) in Wireless Access Points (AP) to arbitrate the wireless channel among Wireless Stations (STAs). However, DCF poses serious ...

In the early 1990s, Houston-based Anadarko Petroleum Corporation outbid competitors for the Tanzanite block in the Gulf of Mexico. It found oil and gas there in 1998 and was producing within three years. The Tanzanite discovery is significant not so much for an abundance of oil and gas, but that in bidding for it Anadarko broke with industry tradition. Rather than using only conventional discou...

Existing backoff scheme’s optimization of IEEE 802.11 DCF MAC protocol consider only saturated networks or asymptotic conditions. In real situations, traffic is bursty or streamed at low rates so that stations do not operate usually in saturated regime. In this work, we propose and analyze a backoff enhancement for IEEE802.11 DCF that requires information only about the network size and that is...