Low-temperature chemical vapor deposition of highly doped n-type epitaxial Si at high growth rate

We investigated the growth of in-situ n-type doped epitaxial Si layers with arsenic and phosphorus by means of low-temperature chemical vapor deposition using trisilane as Si-precursor. Indeed, in order to prevent the alteration of the characteristics of the devices which are already present on the wafer, an epitaxy process at low temperature is highly desired for applications such as BiCMOS. In this work, the varying parameters are the deposition temperature, the Si-precursor mass flow and the dopant gas flow. As a result, a process for the deposition of heavily doped epilayers was demonstrated at 600 °C with high deposition rate, which is important for maintaining high throughput and low process cost. We showed that using trisilane as a Si-precursor resulted in a much more linear n-type doping behavior than using dichlorosilane. Therefore it allowed an easier process control and a wider dynamic doping range. Our process is an interesting route for the epitaxy of a low-resistance emitter layer for bipolar transistor application.     

Real hypersurfaces in a complex space form with a condition on the structure Jacobi operator

In this paper we classify the real hypersurfaces in a non-flat complex space form with its structure Jacobi operator R _ξ satisfying (? _X R _ξ )ξ = 0, for all vector fields X in the maximal holomorphic distribution D. With this result, we prove the non-existence of real hypersurfaces with D-parallel as well as D-recurrent structure Jacobi operator in complex projective and hyperbolic spaces. We can also prove the non-existence of real hypersurfaces with recurrent structure Jacobi operator in a non-flat complex space form as a corollary.     

Single‐molecule surface‐enhanced Raman scattering of fullerene C60

We achieved single‐molecule surface‐enhanced Raman scattering (SM‐SERS) spectra from ultralow concentrations (10⁻¹⁵ M) of fullerene C₆₀ on uniformly assembled Au nanoparticles. It was found that resonant excitation at 785 nm is a powerful tool to probe SM‐SERS in this system. The appearance of additional bands and splitting of some vibrational modes were observed because of the symmetry reduction of the adsorbed molecule and a relaxation in the surface selection rules. Time‐evolved spectral fluctuation and ‘hot spot’ dependence in the SM‐SERS spectra were demonstrated to result from the single‐molecule Raman behavior of the spherical C₆₀ on Au nanoparticles. Copyright © 2010 John Wiley & Sons, Ltd.     

Potential‐induced Raman behavior of individual (R)‐di‐2‐naphthylprolinol molecules on a Ag‐modified Ag electrode

The applicability of surface‐enhanced Raman spectroscopy is demonstrated to probe the adsorption behavior of individual molecules on a Ag electrode. High‐quality SERS spectra of (R)‐di‐2‐naphthylprolinol (DNP) were obtained from ultradilute solutions (10⁻¹² M ) on the Ag‐nanoparticle‐modified Ag electrode, which is attributed to the high electromagnetic (EM) effect of the SERS‐active system as well as to the strong adsorption and interaction of DNP molecules with Ag. The stable SERS spectra present remarkable potential dependence, which gives evidence for the behavior of individual DNP molecules on the Ag surface. Based on statistical analysis for the probability of DNP molecules located in ‘hot spots’, we propose an SERS mechanism for individual molecules in the electrode system, in combination with the hot‐spot model and orientation of the probe molecules. Copyright © 2010 John Wiley & Sons, Ltd.     

New reagents for increasing ESI multiple charging of proteins and protein complexes

The addition of m-nitrobenzyl alcohol (m-NBA) was shown previously (Lomeli et al., J. Am. Soc. Mass Spectrom. 2009, 20, 593–596) to enhance multiple charging of native proteins and noncovalent protein complexes in electrospray ionization (ESI) mass spectra. Additional new reagents have been found to “supercharge” proteins from nondenaturing solutions; several of these reagents are shown to be more effective than m-NBA for increasing positive charging. Using the myoglobin protein-protoporphyrin IX (heme) complex, the following reagents were shown to increase ESI charging: benzyl alcohol, m-nitroacetophenone, m-nitrobenzonitrile, o-NBA, m-NBA, p-NBA, m-nitrophenyl ethanol, sulfolane (tetramethylene sulfone), and m-(trifluoromethyl)-benzyl alcohol. Based on average charge state, sulfolane displayed a greater charge increase (61%) than m-NBA (21%) for myoglobin in aqueous solutions. The reagents that promote higher ESI charging appear to have low solution-phase basicities and relatively low gas-phase basicities, and are less volatile than water. Another feature of mass spectra from some of the active reagents is that adducts are present on higher charge states, suggesting that a mechanism by which proteins acquire additional charge involves direct interaction with the reagent, in addition to other factors such as surface tension and protein denaturation.     

The sample average approximation method for empty container repositioning with uncertainties

One of the challenges faced by liner operators today is to effectively operate empty containers in order to meet demand and to reduce inefficiency in an uncertain environment. To incorporate uncertainties in the operations model, we formulate a two-stage stochastic programming model with random demand, supply, ship weight capacity, and ship space capacity. The objective of this model is to minimize the expected operational cost for Empty Container Repositioning (ECR). To solve the stochastic programs with a prohibitively large number of scenarios, the Sample Average Approximation (SAA) method is applied to approximate the expected cost function. To solve the SAA problem, we consider applying the scenario aggregation by combining the approximate solution of the individual scenario problem. Two heuristic algorithms based on the progressive hedging strategy are applied to solve the SAA problem. Numerical experiments are provided to show the good performance of the scenario-based method for the ECR problem with uncertainties.     

A container yard storage strategy for improving land utilization and operation efficiency in a transshipment hub port

This paper studies the storage yard management problem in a busy transshipment hub, where intense loading and unloading activities have to be considered at the same time. The need to handle huge volumes of container traffic and the scarcity of land in the container port area pose serious challenges for the port operator to provide efficient services. A consignment strategy with a static yard template has been used to reduce the level of reshuffles in the yard, but it sacrifices on land utilization because of exclusive storage space reservation. Two space-sharing approaches are proposed to improve on the land utilization through dynamic reservation of storage space for different vessels during different shifts. Meanwhile, workload assignment among reserved spaces will also satisfy the high-low workload balancing protocol to reduce traffic congestion in the yard. A framework which integrates space reservation and workload assignment is proposed. Experimental results show that the framework is able to provide solutions for containers handling within much less storage space, while guarantee the least yard crane deployment.