The controlled fabrication of nanopores by focused electron-beam-induced etching.

The fabrication of nanometric holes within thin silicon-based membranes is of great importance for various nanotechnology applications. The preparation of such holes with accurate control over their size and shape is, thus, gaining a lot of interest. In this work we demonstrate the use of a focused electron-beam-induced etching (FEBIE) process as a promising tool for the fabrication of such nanopores in silicon nitride membranes and study the process parameters. The reduction of silicon nitride by the electron beam followed by chemical etching of the residual elemental silicon results in a linear dependence of pore diameter on electron beam exposure time, enabling accurate control of nanopore size in the range of 17-200 nm in diameter. An optimal pressure of 5.3 x 10(-6) Torr for the production of smaller pores with faster process rates, as a result of mass transport effects, was found. The pore formation process is also shown to be dependent on the details of the pulsed process cycle, which control the rate of the pore extension, and its minimal and maximal size. Our results suggest that the FEBIE process may play a key role in the fabrication of nanopores for future devices both in sensing and nano-electronics applications.

Variability in head circumference growth rate during the first 2 years of life.

The head circumference (HC) curves were plotted for a group of 415 healthy full-term babies over the first 2 years of life. Two hundred ten (51%) of the cohort demonstrated HC variability, defined as an HC acceleration or deceleration of at least 1 centile curve for at least 2 months. Of these, the deceleration pattern was predominant (80.9%), and also frequently permanent (87%). The HCs of 3 (1.42%) of 210 infants with HC variability ended up with a deviation of 2 standard deviations or more from the mean. The onset of HC transition occurred from the mean age of 1.3 months, and the new curve had stabilized by age 13 months in 95% of the study group. Parallel changes occurred in body weight and body length in approximately 48% of the total cohort, but more frequently in the variable-HC group. The clinical interpretation of these findings is discussed.

Magnetic-film atom chip with 10 µm period lattices of microtraps for quantum information science with Rydberg atoms.

We describe the fabrication and construction of a setup for creating lattices of magnetic microtraps for ultracold atoms on an atom chip. The lattice is defined by lithographic patterning of a permanent magnetic film. Patterned magnetic-film atom chips enable a large variety of trapping geometries over a wide range of length scales. We demonstrate an atom chip with a lattice constant of 10 µm, suitable for experiments in quantum information science employing the interaction between atoms in highly excited Rydberg energy levels. The active trapping region contains lattice regions with square and hexagonal symmetry, with the two regions joined at an interface. A structure of macroscopic wires, cutout of a silver foil, was mounted under the atom chip in order to load ultracold (87)Rb atoms into the microtraps. We demonstrate loading of atoms into the square and hexagonal lattice sections simultaneously and show resolved imaging of individual lattice sites. Magnetic-film lattices on atom chips provide a versatile platform for experiments with ultracold atoms, in particular for quantum information science and quantum simulation.

ITO pattern fabrication of glass platforms for electropolymerization of light sensitive polymer for its conjugation to bioreceptors on a micro-array.

We present herein an effective and versatile method to fabricate a micro-patterned structure of conductive polymer, poly(pyrrole-benzophenone), on Indium Tin Oxide (ITO) glass chips for the subsequent photo-immobilization of various bioreceptor, antigens. Such methodologies are based on photolithography of ITO pattern fabrication on non-conductive surfaces, glass slides, and on a photo-active electrogenerated polymer films. The photo-active polymer serves as a substrate platform for the photo-immobilization of the bioreceptor reagents used for subsequent immunoreactions. We were able to show the resolution of electropolymerization on an ITO pattern as well as immobilization of more than one bioreceptor for the simultaneous detection of several analytes. The antigen micro-arrays were tested for sensitivity, specificity, and overall practicality for the simultaneous detection of analyte anti-Cholera Toxin B, anti-Hepatitis B virus surface and core protein antibodies. In addition we used our pattern ITO-poly(pyrrole-benzophenone) micro-array for the detection of serum samples of Hepatitis B virus patients previously screened by a standard hospital detection method.

Preauricular tags and pits in the newborn: the role of hearing tests.

The aim of this study was to determine the role of audiometry in a group of newborn infants with preauricular tags or pits. During the 2 years of prospective study, 26 infants were born with preauricular tags or pits (5.7 per 1,000 livebirths) and were assessed for hearing impairment by performing behavioural audiometry on day 3 of life and brainstem-evoked response audiometry at 4 months of age. Five infants had associated congenital anomalies (19%). The behavioural audiometry was abnormal in seven infants (27%). The evoked response audiometry was abnormal in 4/23 (17%) newborn infants with isolated tags or pits, and revealed both conductive and/or sensorineural hearing impairment. The incidence of hearing impairment with isolated preauricular tag/pit was significantly higher (p < 0.001) than the incidence reported in preschool children. We conclude that hearing assessment is recommended in the routine evaluation of the newborn with isolated preauricular tags or pits. This policy may facilitate early diagnosis and treatment of hearing impairment in this population.