Optical trapping force reduction and manipulation of nanoporous beads

We studied the interaction of infrared optical traps with controlled-pore glass (CPG) beads in aqueous medium. The lateral optical trapping force and stiffness were experimentally found considerably smaller than those of their solid counterparts. The simulation using an average refractive index revealed significant losses of effective trapping efficiency, which quantitatively agreed well with experimentally fitted curves. This effect was ascribed to the reduced relative refractive index of medium-filled CPG beads with respect to the medium. Combining optical trapping with mechanical confinements, we demonstrated a microfluidic platform allowing for the synthesis of multiple DNA oligonucleotide sequences on individual beads of interest.     

Extended operations after induction therapy for stage IIIb (T4) non-small cell lung cancer

Twenty-three patients with stage IIIb (T4) non-small cell lung cancer received induction chemotherapy (median, 2 cycles) with (n = 12) or without (n = 11) radiation (median, 45 Gy) before operation. Nine tumors involved the carina (n = 8) or lateral tracheal wall (n = 1), 11 were located centrally and invaded the proximal pulmonary artery (n = 6), veins (n = 3), or both (n = 2), three were apical tumors involving T4 structures, and six were associated with histologically diseased mediastinal nodes. Five complete and 18 partial responses were observed after induction treatment. Resection of all residual tumor at the primary site and involved vestiges was possible in 21 patients (91%); in two apical tumors, tumor was left behind. Nine right tracheal sleeve and 11 intrapericardial pneumonectomies and three resections of apical tumors were performed; 11 patients (48%) had radical mediastinal lymph node dissection. Complete sterilization of the primary tumor was observed in 3 patients (13%). Mean operating time was 209.3 +/- 86.8 minutes, and mean blood loss was 896.9 +/- 1031 mL. Major postoperative complications occurred in 6 patients (26%), including hemothorax requiring drainage (n = 1) or reoperation (n = 1), acute distress syndrome (n = 2), and bronchopleural fistula (n = 2), and their incidence was significantly higher (p = 0.0003) among patients receiving induction chemoradiation than among those receiving chemotherapy alone (42 versus 9%). Early (< 1 month) postoperative mortality was 8.6% (n = 2). With a median follow-up of 25 months (range, 12 to more than 39 months), the projected 3-year overall survival was 54%.(ABSTRACT TRUNCATED AT 250 WORDS)     

Vacuum ellipsometry as a method for probing glass transition in thin polymer films

A vacuum ellipsometer has been designed for probing the glass transition in thin supported polymer films. The device is based on the optics of a commercial spectroscopic phase-modulated ellipsometer. A custom-made vacuum chamber evacuated by oil-free pumps, variable temperature optical table, and computer-based data acquisition system was described. The performance of the tool has been demonstrated using 20-200 nm thick poly(methyl methacrylate) and polystyrene films coated on silicon substrates at 10(-6)-10(-8) torr residual gas pressure. Both polymers show pronounced glass transitions. The difficulties in assigning in the glass transition temperature are discussed with respect to the experimental challenges of the measurements in thin polymer films. It is found that the experimental curves can be significantly affected by a residual gas. This effect manifests itself at lower temperatures as a decreased or even negative apparent thermal coefficient of expansion, and is related to the uptake and desorption of water by the samples during temperature scans. It is also found that an ionization gauge--the standard accessory of any high vacuum system--can cause a number of spurious phenomena including drift in the experimental data, roughening of the polymer surface, and film dewetting.     

Application of X-rays to nanolithography

The development of a successful fabrication process for electron devices with dimensions in the sub-100-nm domain will require a form of a high-resolution and high-volume patterning. In this paper we discuss the extensibility of X-ray lithography to this domain in terms of the resolution of the technique, considering in detail the effect of diffraction and photoelectrons. We show that optimized masks and exposure systems can deliver with relative ease patterning in the 70-50-nm region, while phase-shifting techniques can extend the resolution to sub-40 nm. High volume is provided by the use of the mask. The challenge remains in the fabrication of the IX mask, and in the achievement of the necessary placement accuracy     

An optimization design method for chemically amplified resistprocess control

A novel optimization method called chemically-amplified resist process optimization design (CARPOD) applicable to the chemically amplified resist (CAR) process development is described. The method finds the optimal process conditions and the design center (maximum process tolerance space) of a CAR process with minimum experimental runs. First a modified response surface method is used to form the numerical response surface of a CAR, and its most sensitive point, which is the minimum requirement of X-ray dose, is located as an optimal process condition by an optimization method called POSM under the constraint of the contrast of the photoresist. Second, the design center is found to maximize the process tolerance space around the optimal process condition. Third, verifications are made on the optimal design as well as the design center. The process optimization of AZ PF-514 has been used as an example to show that the CARPOD method can identify the optimal process condition as well as the maximum tolerable parameter space with minimum experimental runs