1,721,001 research outputs found
Orbit determination of resident space objects using the P-band mono-beam receiver of the Sardinia Radio Telescope
Full text linkThe population of space debris in near-Earth space is continuously growing and it represents a serious problem for active satellites and spacecraft. A performant ground-based and space-based network of sensors is necessary for space surveillance and consequently to prevent new collisions and monitoring atmospheric reentry of these objects. This paper illustrates the possible role of the Italian ground-based novel bi-static radar sensor, named BIRALET, for space monitoring and resident space objects tracking. The main characteristics of the receiver system, the Sardinia Radio Telescope with its P-band mono-beam receiver, are described in detail. Then, a preliminary analysis of the performance of the sensor is presented, and the results of numerical simulations are shown, providing a general overview on both observation capabilities and orbit determination accuracy achievable with the Sardinia Radio Telescope
An Updated View of Cisplatin Transport
No full textCisplatin, or cis-diamminedichloridoplatinum(II) cis-[PtCl2(NH3)2], is a platinum-based anticancer drug largely used for the treatment of various types of cancers, including ovarian and colorectal carcinomas, sarcomas, and lymphomas. Together with other platinum-based drugs, it triggers malignant cell death by binding to nuclear DNA, which appears to be the ultimate target. In addition to passive diffusion across the cell membrane, other transport mechanisms, including endocytosis and some active or facilitated transport, are currently proposed to play a pivotal role in the uptake of platinum-based drugs. In this microreview, we will give an updated view of the current literature regarding cisplatin transport and processing inside the cell, with special emphasis on the membrane copper transporter Ctr1 and the soluble copper chaperone Atox1
Platinum
No full textThe name platinum is derived from the Spanish term platina, which is literally translated into little silver. It is one of the rarest elements on Earth’s crust (the average abundance is approximately 5 mg kg!1) and the least reactive (the noblest among metals). It occurs in some nickel and copper ores along with some native deposits. Native platinum was first used by pre- Columbian South American natives to produce artefacts. The first European reference to platinum appeared in 1557 in the writings of the Italian humanist Julius Caesar Scaliger as a description of an unknown noble metal found in Mexico, ‘‘which no fire nor any Spanish artifice has yet been able to liquefy’’, but it was not until Antonio de Ulloa published a report on a new metal of Colombian origin in 1748 that it became investigated by scientists
Titan Mission Feasibility Study for Bi-Static Sar Mapping of the Planet by Formation Flying
No full textCisplatin handover between copper transporters: the effect of reducing agents
No full textCopper (Cu) transporters emerged as key factors at the basis of the biological response to antitumor platinum (Pt) drugs, which are among the most potent and broadly used chemotherapeutics. ATP7A and ATP7B (the Menkes and Wilson disease proteins, respectively) appear to be implicated in promoting tumor cell resistance to cisplatin. Cu-ATPases could bind the drug and, with the alleged involvement of the chaperone ATOX1, contribute to cell detoxification and survival. Here, we report the spectroscopic characterization of cisplatin binding to ATOX1 and MNK1, the first metal-binding domain of ATP7A, in the presence of the physiological reducing agent glutathione, a sulfur-containing molecule responsible for the majority of Pt detoxification in the cytosol. Under conditions mimicking the cellular environment, we show that cisplatin transfer from ATOX1 to MNK1 does not occur at a detectable rate. These results appear to contradict other literature data which, however, were obtained in the presence of exogenous reducing agents such as tris(2-carboxyethyl)phosphine (TCEP) having good coordinating ability for soft metal ions (such as Pt) and strong trans-labilizing effect. A better understanding of Pt drug processing by Cu trafficking proteins under physiological conditions may help to answer key issues, such as drug availability in tumor cells and resistance
Impact Probability Computation for Neo Resonant Returns Through a Polynomial Representation of the Line of Variations
Full text linkEstimation of impact probability of asteroids and space debris through Monte Carlo Line Sampling and Subset Simulation
Full text linkImpact probability computation of near-Earth objects using Monte Carlo line sampling and subset simulation
Full text linkThis work introduces two Monte Carlo (MC)-based sampling methods, known as line sampling and subset simulation, to improve the performance of standard MC analyses in the context of asteroid impact risk assessment. Both techniques sample the initial uncertainty region in different ways, with the result of either providing a more accurate estimate of the impact probability or reducing the number of required samples during the simulation with respect to standard MC techniques. The two methods are first described and then applied to some test cases, providing evidence of the increased accuracy or the reduced computational burden with respect to a standard MC simulation. Finally, a sensitivity analysis is carried out to show how parameter setting affects the accuracy of the results and the numerical efficiency of the two methods
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