All the realistic free fermionic models utilize a set of basis vectors, the NAHE set, that correspond to Z 2 × Z 2 orbifold compactification with nontrivial background fields. I argue that the realistic features of free fermionic models, like the number of generations and the fermion mass spectrum are due to the underlying Z 2 × Z 2 orbifold compactification. As a unified theory of gravity and ...

We investigate poly~methylmethacrylate! ~PMMA! development processing with cold developers ~4–10 °C! for its effect on resolution, resist residue, and pattern quality of sub-10 nm electron beam lithography ~EBL!. We find that low-temperature development results in higher EBL resolution and improved feature quality. PMMA trenches of 4–8 nm are obtained reproducibly at 30 kV using cold developmen...

Bobbi Roop Advanced Photon Source Argonne National Laboratory Argonne,IL 60439 An x-ray photoemission spectroscopic study was undertaken to compare the cleaning of the Advanced Photon Source (APS) aluminum extrusion storage ring vacuum chambers after machining with and ~thout water soluble coolants. While there was significant contamination left by the coolants, the cleaning process was capable...

The cha nges in chemical structure occu ring in pol y (vinyl chloride) as a res ul t of heati ng ina vacu um in t he range 100° to 400° C were studied using infrared spectropho to metry. The pri ncipa l changes occ urri ng in t he residue during p yrolysis in a vacuum were the format ion of unsaturated s tructures a nd a change from an al iphatic spectrum to one showing aromatic absorption. The...

Singly-protonated proline-containing peptides with N-terminal arginine are photodissociated with vacuum ultraviolet (VUV) light in an ESI linear ion trap/orthogonal-TOF (LIT/o-TOF). When proline is the nth residue from the N-terminus, unusual b(n) + 2 and a(n) + 2 ions are observed. Their formation is explained by homolytic cleavage of the C(alpha)-C bond in conjunction with a rearrangement of ...

Given an arbitrary n, we consider anisotropic quadratic forms of dimension n over all fields of characteristic = 2 and prove that the height of an n-dimensional excellent form (depending on n only) is the (precise) lower bound of the heights of all forms of dimension n.

objective: the main objective pursued in this paper is to investigate the energy consumption for drying of potato slices using vacuum-infrared drying method. methods: drying of potato slices with the thicknesses of 1, 2 and 3 mm were conducted at vacuum levels of zero (without vacuum), 20, 80 and 140 mm [hg], infrared radiation at power levels of 100, 150 and 200 w in the three repetition. resu...

An ancient organic residue was collected from the bottom of a Greco-Italian amphora found in the Adriatic Sea and investigated by direct GC and GC-MS analysis. The headspace composition was determined by HS-SPME using: (1) DVB/CAR/PDMS and (2) PDMS/DVB fibres. Higher percentages of benzene derivatives, monoterpenes and other low-molecular aliphatic compounds were obtained by method (1) in contr...

The flowing liquid surface retention experiment (FLIRE) has been designed to provide fundamental data on the retention and pumping of He, H and other species in flowing liquid surfaces. The FLIRE concept uses an ion source with current densities near 0.5 mA/cm and a working distance of 30 /40 mm. The ion source injects 300 /5000 eV ions into a flowing stream of liquid lithium at nearly normal i...

PSD does not usually generate a complete series of y-type ions, particularly at high mass, and this is a limitation for de novo sequencing algorithms. It is demonstrated that b(2) and b(3) ions can be used to help assign high mass x(N-2) and x(N-3) fragments that are found in vacuum ultraviolet (VUV) photofragmentation experiments. In addition, v(N)-type ion fragments with side chain loss from ...