High quality single shot diffraction patterns using ultrashort megaelectron volt electron beams from a radio frequency photoinjector.

Single shot diffraction patterns using a 250-fs-long electron beam have been obtained at the UCLA Pegasus laboratory. High quality images with spatial resolution sufficient to distinguish closely spaced peaks in the Debye-Scherrer ring pattern have been recorded by scattering the 1.6 pC 3.5 MeV electron beam generated in the rf photoinjector off a 100-nm-thick Au foil. Dark current and high emittance particles are removed from the beam before sending it onto the diffraction target using a 1 mm diameter collimating hole. These results open the door to the study of irreversible phase transformations by single shot MeV electron diffraction.

GPC3 mutation analysis in a spectrum of patients with overgrowth expands the phenotype of Simpson-Golabi-Behmel syndrome.

Simpson-Golabi-Behmel syndrome (SGBS) is an X-linked overgrowth syndrome caused by deletions in glypican 3 (GPC3). SGBS is characterized by pre- and postnatal overgrowth, a characteristic facial appearance, and a spectrum of congenital malformations which overlaps that of other overgrowth syndromes. We performed GPC3 deletion screening on 80 male patients with somatic overgrowth in the following categories: SGBS (n = 19), possible SGBS (n = 26), including families in which individuals had previously been diagnosed with other overgrowth syndromes, and Wiedemann-Beckwith syndrome (WBS) (n = 35). Using exon-specific PCR and Southern blot analysis, we identified seven GPC3 deletions. In most cases a clear X-linked family history was not present. In two cases, GPC3 deletions were identified in patients belonging to pedigrees published previously as other overgrowth syndromes: one with a diagnosis of Sotos syndrome and the other Perlman syndrome with nephroblastomatosis. A third patient developed hepatoblastoma, a tumor type not previously described in SGBS. No GPC3 deletions were identified among the WBS patients. Direct sequencing of all GPC3 exons in the remaining 13 SGBS patients without GPC3 deletions did not identify any further mutations, raising the possibility of alternative silencing mechanisms and/or other genes in the pathogenesis of SGBS. Our results validate the clinical specificity of the facial appearance, skeletal/hand anomalies, and supernumerary nipples in patients with GPC3 deletions. Our data also suggest that nephroblastomatosis and hepatoblastoma are included in the phenotypic spectrum of GPC3 deletions and SGBS, underscoring the importance of tumor surveillance in these children.

Intense plasma discharge source at 13.5 nm for extreme-ultraviolet lithography.

We measured an emission of 6 mJ/pulse at 13.5 nm produced by the Li(2+) Lyman-? transition excited by a fast capillary discharge, using a lithium hydride capillary. 75% of the energy emanated from a spot size of 0.6 mm. The emission is narrow band and would thus be useful in extreme-ultraviolet lithography imaging systems that use Mo:Si multilayer mirrors. The output within the bandwidth of Mo:Si mirrors was comparable with that of a laser-produced plasma (LPP), and the wallplug efficiency of 0.1% was nearly an order of magnitude better than that of a LPP.

Velocity characterization of particulate debris from laser-produced plasmas used for extreme-ultraviolet lithography.

Debris from laser-produced plasmas created with solid Sn and Au targets has been characterized according to speed and particulate size. Conditions for the experiments were those appropriate for producing an optimum laser-produced plasma emission at 13.5 nm for use in extreme-ultraviolet lithography. Results in the form of histogram data show that the speed distribution of the debris particulates is quite varied and in general exhibits an upper limit of ~640 m/s. In the case of Sn a peak in the velocity distribution is observed near 300 m/s. Small particulates, of the order of 1 µm or less, constitute the majority of the particulate emission in both materials. The implications for debris reduction based on the measurements are also discussed.

Characterization and control of laser plasma flux parameters for soft-x-ray projection lithography.

Laser plasmas are intrinsically an attractive soft-x-ray source for projection lithography. Compact, flexible, and small enough to be dedicated to a single installation, they offer an alternative to costly multi-installation synchrotron sources. For laser plasmas to provide ideal sources of soft x rays for projection lithography, their properties must be tuned to optimize several critical parameters. High x-ray conversion in the spectral band relevant to projection lithography is obviously required and has already received the attention of several studies. However, other features, such as the spectral content and direction of the x-ray emission, the plasma and particulate emission, the technology of the target, and efficient laser design, must also be optimized. No systematic study of all these features specifically for projection lithography has yet been made. It is our purpose to optimize these parameters in a coordinated approach, which leads to the design of a source that satisfies all the demanding requirements of an operating lithographic installation. We make an initial investigation of the plasma and particle emission of plasmas that have previously been shown to be good x-ray converters to the 13-nm band. The importance of the results reported may well force new approaches to the design of laser plasma soft-x-ray sources for projection lithography.

Investigation of distortion and damage of molybdenum†silicon multilayer reflective coatings with high-intensity ultraviolet radiation.

Studies are performed to determine an upper limit on the optical damage threshold of a soft-x-ray molybdenum-silicon multilayer reflective coating by the use of a 308-nm, 15-ns pulse from a Xe-Cl excimer laser in order to simulate the potential damage induced by the x-ray flux from a pulsed laser-produced plasma. Experimental results yield a value of 0.26 J/cm(2) to produce visible signs of damage as determined by optical microscopy. Experiments are conducted first on silicon, as a reference point of a bulk material, and then applied to molybdenum-silicon in an effort to facilitate a theoretical comparison between a simple and a more complicated material. Theoretical predictions are in reasonable agreement with experimental results, but suggest that a lower value of 0.085 J/cm(2) might cause significant thermal-induced damage.

An unusual distal arthrogryposis.

We report on a mother and her dizygotic twin fetuses who were affected with distal arthrogryposis. In addition the mother has cervical vertebral anomalies, scoliosis, short stature, nuchal and axillary pterygia, and unusual facial appearance. The fetuses had a short neck, pterygium colli, retrognathia, and mild apparent scoliosis. We think that these three individuals have a previously undescribed type of distal arthrogryposis.

Acrofacial dysostosis with severe facial clefting and limb reduction.

We describe two unrelated patients with a severe form of acrofacial dysostosis. Facial defects in both include coloboma of the lids, micrognathia, lateral oral clefting, palatal clefting, and severe auricular anomalies, with one showing bilateral cleft lip and right oblique facial clefting as well. Both have absent forearms and thumbs. Lower limbs were severely reduced in both infants with the feet attached either to the femur or directly to the trunk. Parental consanguinity was present in one case. The condition in these two infants appears to represent either a severe form of Nager acrofacial dysostosis or a new type of acrofacial dysostosis.

Terminal and interstitial deletions of the long arm of chromosome 7: a review with five new cases.

Sixteen cases of terminal deletions and 17 cases of interstitial deletions of the long arm of chromosome 7 have been reported to date. We present two new cases of the former and three of the latter. The somatic changes in these patients are tabulated and an update on the anomalies associated with the various cytogenetic entities is presented. Changes found in over one-third of patients with 7q terminal deletion syndrome include: developmental delay, pre- and postnatal growth retardation, generalized hypotonia, abnormal electroencephalograms with or without seizures, feeding problems in infancy, microcephaly, prominent forehead, ocular hypertelorism, eye defects, broad nasal bridge, bulbous nasal tip, auricular malformations, micrognathia, chest abnormalities, genital malformations in males, and abnormal palmar and plantar creases. Evidence for the localization of the Kidd blood group gene on chromosome 7 distal to band q32, as suggested by previous reports, is reviewed; we conclude that the evidence does not warrant placement of the gene in this region of the genome.

Hirschsprung disease: etiologic implications of unsuccessful prenatal diagnosis.

We describe an infant with Hirschsprung disease (congenital aganglionosis of the intestine) involving the colon and terminal ileum. Midtrimester prenatal diagnosis of this disorder in this infant was attempted utilizing amniotic fluid disaccharidase analyses, ultrasound, and amniography. Decreased disaccharidase activities in amniotic fluid have been reported previously in association with other forms of intestinal obstruction. At 15 weeks' gestation, normal amniotic fluid disaccharidase levels were obtained. Serial ultrasound evaluations did not indicate any pathology, and the results from amniography were inconclusive. The implication of the normal disaccharidase values is that Hirschsprung disease may in some cases result from degeneration of intestinal ganglia after 16 weeks' gestation rather than from faulty migration of neural crest cells. The inheritance of Hirschsprung disease is generally consistent with sex-modified multifactorial inheritance with a lower threshold of expression in males. The case we report has a family history of three affected first- and second-degree relatives. Autosomal dominance with variable expressivity is a possible explanation in this family.