Off‐Stoichiometric Thiol‐Ene Chemistry to Dendritic Nanogel Therapeutics

A novel platform of dendritic nanogels is herein presented, capitalizing on the self‐assembly of allyl‐functional polyesters based on dendritic‐linear‐dendritic amphiphiles followed by simple cross‐linking with complementary monomeric thiols via UV initiated off‐stoichiometric thiol‐ene chemistry. The facile approach enabled multigram creation of allyl reactive nanogel precursors, in the size range of 190–295 nm, being readily available for further modifications to display a number of core functionalities while maintaining the size distribution and characteristics of the master batch. The nanogels are evaluated as carriers of a spread of chemotherapeutics by customizing the core to accommodate each individual cargo. The resulting nanogels are biocompatible, displaying diffusion controlled release of cargo, maintained therapeutic efficacy, and decreased cargo toxic side effects. Finally, the nanogels are found to successfully deliver pharmaceuticals into a 3D pancreatic spheroids tumor model.     

An adaptive notch-filter-based frequency-difference detector andits applications

A frequency-difference detector (FDD) based on an adaptive notch filter is proposed. Frequency detectors are useful in decreasing acquisition times in phase-locked-loop and Costas-loop-based clock and carrier-recovery systems. To avoid certain drawbacks associated with signal down-conversion to baseband, the input is initially processed in the bandpass domain. In applications where limits on acquisition time demand a wide closed-loop tracking bandwidth, the output of the proposed FDD has less inherent ripple and bias when compared with a quadricorrelator, a commonly used FDD. Two applications of the proposed FDD in the demodulation of BPSK data are presented     

Required bandwidth, unwanted emission, and data power efficiencyfor residual and suppressed carrier systems-a comparative study

This paper presents a new concept for required bandwidth along with a method for computing this bandwidth and the associated undesired emission for the classes of PCM/PSK/PM, PCM/PM and BPSK signals. The PCM/PSK/PM signals considered here employ either a square wave or sine-wave subcarrier with NRZ data format. On the other hand, the PCM/PM and BPSK signals use either a Bi-phase or an NRZ data format. Furthermore, the maximum allowable required bandwidth in the presence of noise and the data power efficiency for these modulation schemes will also be investigated. The term “data power efficiency” as considered in this paper consists of two principal components, namely, the amount of power contained in the data channel, and the symbol signal-to-noise ratio (SSNR) degradation due to the presence of intersymbol interference (ISI) for a specified required bandwidth. This paper evaluates both of these components numerically for the modulation schemes considered and the results are then compared. Furthermore, the impact of baseband filtering on the required bandwidth is also investigated in this paper     

Subnanometer Analysis and Modeling of MBE Grown InP Based MODFETs

InGaAs/InAlAs double-doped double-strained modulation-doped field-effect transistors OD-SMODFETs)1 were grown by solid source molecular beam epitaxy. The structures were characterized using high resolution x-ray diffraction, Hall effect, and cross-sectional scanning tunneling microscopy. A record two-dimensional electron gas (2DEG) sheet density of 8.5 × 10¹²/cm² and 8.1 × 10¹²/cm² for 300 and 77K, respectively, was achieved. The mobility was 6500 and 12000 cm²/ Vs for 300 and 77K, respectively. To the author’s knowledge,² the previous record 2DEG result was 6.58 × 10¹²/cm². The electron mobility was limited by alloy scattering and interface roughness caused by the presence of “clustering.” Using cross-sectional scanning tunneling microscopy to verify the presence of these clusters, we have the first images of the lattice matched InAlAs (spacer)-InGaAs (quantum well) interface. These images reveal clusters that have approximate spherical or cylindrical shapes with equivalent cubic dimensions ranging from 25 to 45Å.     

Gröbner Bases and Multidimensional FIR Multirate Systems

The polyphase representation with respect to sampling lattices in multidimensional (M-D) multirate signal processing allows us to identify perfect reconstruction (PR) filter banks with unimodular Laurent polynomial matrices, and various problems in the design and analysis of invertible MD multirate systems can be algebraically formulated with the aid of this representation. While the resulting algebraic problems can be solved in one dimension (1-D) by the Euclidean Division Algorithm, we show that Gröbner bases offers an effective solution to them in the M-D case.     

Narrow-channel GaInP/InGaAs/GaAs MODFETs for high-frequency andpower applications

We have developed a new concept of narrow (50-80 Å) channel MODFETs. It is shown theoretically and experimentally that only the ground energy level is populated in the narrow-channel device. A new technique to measure mobility at the highest energies of the two-dimensional electron gas (2-DEG) was introduced. With the help of this technique it is shown that, in wide wells, electrons in the excited energy levels have low mobility and consequently degrade device performance. It is shown theoretically and experimentally that the narrow-channel device has a higher electron sheet density and mobility and consequently better performance than a conventional wide-channel MODFET. Excellent quality Ga_xIn_1-xP/In_yGa_1-yAs/GaAs MODFETs with a pseudomorphic barrier and a pseudomorphic channel were grown by MBE and OMVPE. Higher than 3.4·10¹² cm^-2 electron sheet densities for single-side-doped MODFETs on GaAs substrate were measured. One-tenth micron gate length MODFETs achieved f _T's over 100 GHz and f_max's over 180 GHz. These results are comparable to the previously reported results for GaInP MODPET with graded barriers, however the device structure is much simpler     

Application of Reconfigurable CORDIC Architectures

Reconfiguration enables the adaption of Coordinate Rotation DIgital Computer (CORDIC) units to the specific needs of sets of applications, hence creating application specific CORDIC-style implementations. Reconfiguration can be implemented at a high level, taking the entire CORDIC unit as a basic cell (CORDIC-cells) implemented in VLSI, or at a low level such as Field-Programmable Gate Arrays (FPGAs). We suggest a design methodology and analyze area/time results for coarse (VLSI) and fine-grain (FPGA) reconfigurable CORDIC units. For FPGAs we implement CORDIC units in Verilog HDL and our object-oriented design environment, PAM-Blox. For CORDIC-cells, multiple reconfigurable CORDIC modules are synthesized with state-of-the-art CAD tools. At the algorithm level we present a case study combining multiple CORDICs based on a geometrical interpretation of a normalized ladder algorithm for adaptive filtering to reduce latency and area of a fully pipelined CORDIC implementation. Ultimately, the goal is to create automatic tools to map applications directly to reconfigurable high-level arithmetic units such as CORDICs.     

SHORT COMMUNICATION: Solar cell efficiency tables (version 25)

Consolidated tables showing an extensive listing of the highest independently confirmed efficiencies for solar cells and modules are presented. Guidelines for inclusion of results into these tables are outlined and new entries since June 2004 are reviewed. Copyright © 2005 John Wiley & Sons, Ltd.     

Low-complexity MIMO blind, adaptive channel shortening

Channel shortening is often employed as a means of mitigating intersymbol and intercarrier interference (ISI and ICI) in systems using multicarrier modulation. The Multicarrier Equalization by Restoration of RedundancY (MERRY) algorithm has previously been shown to blindly and adaptively shorten a channel to the length of the guard interval in a multicarrier system. This paper addresses synchronization and complexity reduction issues that were not dealt with in previous work and provides extensions to and generalizations of the MERRY algorithm. A modification is presented that removes the square root and division needed at each iteration without introducing additional complexity, with the added benefit of allowing the use of constraints other than a unit norm equalizer; an extension is proposed that allows for the use of more data in the MERRY update; the algorithm is generalized to the multiple-input multiple output (MIMO) and fractionally spaced cases; a low-complexity, blind symbol synchronization technique is proposed, and a method is proposed for blind initialization of the algorithm to avoid slow modes of convergence. Each extension to the basic MERRY algorithm is accompanied by an illustrative simulation example.     

Photo‐Induced Functionalization of Spherical and Planar Surfaces via Caged Thioaldehyde End‐Functional Polymers

The synthesis and application of a novel reversible addition‐fragmentation chain transfer (RAFT) agent carrying a photocaged thioaldehyde moiety is described (λ_max = 355 nm). RAFT polymerization of styrene, dimethylacrylamide and a glycomonomer is evidenced (3600 g mol^?1 ≤ M_n ≤ 15 000 g mol^?1; 1.07 ≤ ? ≤ 1.20) with excellent end‐group fidelity. The photogenerated thioaldehyde on the chain ends can undergo hetero Diels–Alder reactions with dienes as well as reactions with nucleophiles. The terminal photoreactive polymers are photografted to porous diene‐reactive polymeric microspheres. The grafted particles are in‐depth characterized via scanning electron microscopy, elemental analysis, X‐ray photoelectron spectroscopy, and high resolution FT‐IR microscopy, leading to a qualitative as well as quantitative image of the core–shell objects. Grafting densities up to 0.10 molecules nm^?2 are reached. The versatility of the thioaldehyde ligation is evidenced by spatially resolved grafting of polystyrene onto nucleophilic groups present in poly (dopamine) (PDA)‐coated glass slides and silicon wafers via two‐photon direct laser writing (DLW) imaged by ToF‐SIMS. The combination of thioaldehyde ligation, RAFT polymerization, and DLW allows for the spatially resolved grafting of a vast range of polymers onto various substrates in any desired pattern with sub‐micrometer resolution.