Mass spectrometry (MS) was used to measure the concentrations of drug and biological compounds in plasma and tissues. Matrix-assisted laser desorption/ionization (MALDI) imaging MS (IMS) has recently been applied to the analysis of localized drugs on biological tissue surfaces. In MALDI-IMS, matrix application process is crucial for successful results. However, it is difficult to obtain homogeneous matrix crystals on the tissue surface due to endogenous salts and tissue surface heterogeneity. Consequently, the non-uniform crystals degrade the quality of the spectrum and likely cause surface imaging artifacts. Furthermore, the direct application of matrix solution can cause tissue shrinkage due to the organic solvents. Here, we report an alternative two-step matrix application protocol which combines the vacuum deposition of matrix crystals and the spraying of matrix solution to produce a homogeneous matrix layer on the tissue surface. Our proposed technique can also prevent cracking or shrinking of the tissue samples and improve the ionization efficiency of the distributed exogenous material.
We consider QCD corrections to Higgs boson production through gluon-gluon fusion in hadron collisions. Using the recently evaluated [14] two-loop amplitude for this process and the corresponding factorization formulae [15]-[18] describing soft-gluon bremsstrahlung at O(α 2 S ), we compute the soft and virtual contributions to the next-to-next-to-leading order cross section. We also discuss soft-gluon resummation at next-to-next-to-leading logarithmic accuracy. Numerical results for Higgs boson production at the LHC are presented. ‡ Partially supported by Fundación Antorchas
JHEP05(2001)025exceeds all the other production channels by a factor decreasing from 8 to 5 when M H increases from 100 to 200 GeV. When M H approaches 1 TeV, gg fusion still provides about 50% of the total production cross section.QCD radiative corrections at next-to-leading order (NLO) to gg-fusion were computed and found to be large [10]- [12]. Since approximate evaluations [13] of higher-order terms suggest that their effect can still be sizeable, the evaluation of the next-to-next-to-leading order (NNLO) corrections is highly desirable.In this paper, we perform a first step towards the complete NNLO calculation. We use the recently evaluated [14] two-loop amplitude for the process gg → H and the soft-gluon factorization formulae [15]-[18] for the bremsstrahlung subprocesses gg → Hg and gg → Hgg, Hqq, and we compute the soft and virtual contributions to the NNLO partonic cross section. We also discuss all-order resummation of soft-gluon contributions to next-to-next-to-leading logarithmic (NNLL) accuracy.We use the approximation M t M H , where M t is the mass of the top quark. The results of the NLO calculation in ref. [12] show that this is a good numerical approximation [13] of the full NLO correction, provided the exact dependence on M H /M t is included in the leading-order (LO) term. We can thus assume that the limit M t M H continues to be a good numerical approximation at NNLO. The hadronic cross section for Higgs boson production is obtained by convoluting the perturbative partonic cross sections with the parton distributions of the colliding hadrons. Besides the partonic cross sections, the other key ingredients of the NNLO calculation are the NNLO parton distributions. Even though their NNLO evolution kernels are not fully available, some of their Mellin moments have been computed [19] and, from these, approximated kernels have been constructed [20]. Recently, the new MRST [21] sets of distributions became available 1 , including the (approximated) NNLO densities, which allows an evaluation of the hadronic cross section to (almost full) NNLO accuracy.We use our NNLO result for the partonic cross sections and the MRST parton distributions at NNLO to compute the Higgs boson production cross section at the LHC. In this paper, we do not present numerical results for Run II at the Tevatron. Inclusive production of Higgs boson through gluon-gluon fusion is phenomenologically less relevant at the Tevatron: it is not regarded as a main ...
Barrier coating materials used in plasma display panel (PDP) cells strongly affect the discharge voltages. Although magnesium oxide (MgO) is widely used for barrier coating in the current generation of commercial PDP cells, other alkaline earth oxides have been studied as alternatives and indeed some of them are now known to have lower discharge breakdown voltages for PDP cells, which would increase the energy efficiency of the cells. On the other hand, the resistance against physical sputtering is another critical parameter for barrier coating. In this work, sputtering yields of CaO, SrO and BaO by monochromatic Ne or Xe ion beams are obtained experimentally as functions of beam energy in the range 100–300 eV. Despite the large differences in mass among the targets and incident ions, sputtering yields are found to be similar in magnitude among them for a given incident energy.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.