Design challenges of a 65 nm CMOS stacked folded differential PA structure for mobile communications

In this paper, a novel phase-locked loop (PLL) architecture with multiple charge pumps, which is used to design a fast-locking PLL and a low-phase-noise PLL, is proposed. The effective capacitance and resistance of the loop filter in terms of voltage is scaled up/down according to the locking status by controlling the magnitude and direction of the charge pump current. Two PLLs, one with a fast-locking characteristic and the other with a low-phase-noise characteristic, are designed and fabricated in a 0.35-μm CMOS process based on the proposed architecture. The fast-locking PLL has a locking time of less than 6 μs and a phase noise of −90.45 dBc/Hz at 1 MHz offset. The low-phase-noise PLL has a locking time of 25 μs, a phase noise of −105.37 dBc/Hz at 1 MHz offset, and a reference spur of −50 dBc. Both PLLs have an 851.2 MHz output frequency.     

The Economics and Performance of Satellite Packet Switching

The economics and performance of packet-switched satellite systems operating in a broadcast mode are studied and compared to landline-based systems similar to the ARPANET. The fixed-packet length inefficiencies and the satellite channel utilization of the satellite systems are presented as functions of the message length distribution, the number of earth stations, the average message delay, and the average number of messages generated at each earth station. Some of the economic factors in the design of packetswitched satellite networks are discussed, including hardware costs as a function of technology and system performance. Satellite network configurations with or without backhaul facilities are compared and it is concluded that configurations using backhaul facilities consisting of two 30 mile private leased lines (each 50 kbits/s) are more expensive. Parameters and estimated costs of satellite system configurations are presented and an engineering estimate of the cost function for satellite packet-switched networks is derived and presented in the form of long range average cost curves. Economies of scale with respect to network traffic and diseconomies of scale with respect to the number of network earth stations are found to be present.     

A Mouse-Based Method to Monitor Wheat Allergens in Novel Wheat Lines and Varieties Created by Crossbreeding: Proof-of-Concept Using Durum and A. tauschii Wheats

Wheat allergies are potentially life-threatening because of the high risk of anaphylaxis. Wheats belong to four genotypes represented in thousands of lines and varieties. Monitoring changes to wheat allergens is critical to prevent inadvertent ntroduction of hyper-allergenic varieties via breeding. However, validated methods for this purpose are unavailable at present. As a proof-of-concept study, we tested the hypothesis that salt-soluble wheat allergens in our mouse model will be identical to those reported for humans. Groups of Balb/cJ mice were rendered allergic to durum wheat salt-soluble protein extract (SSPE). Using blood from allergic mice, a mini hyper-IgE plasma bank was created and used in optimizing an IgE Western blotting (IEWB) to identify IgE binding allergens. The LC-MS/MS was used to sequence the allergenic bands. An ancient Aegilops tauschii wheat was grown in our greenhouse and extracted SSPE. Using the optimized IEWB method followed by sequencing, the cross-reacting allergens in A. tauschii wheat were identified. Database analysis showed all but 2 of the durum wheat allergens and all A. tauschii wheat allergens identified in this model had been reported as human allergens. Thus, this model may be used to identify and monitor potential changes to salt-soluble wheat allergens caused by breeding.     

Potential for identification of wild night-flying moths by remote infrared microscopy

There are hundreds of thousands of moth species with crucial ecological roles that are often obscured by their nocturnal lifestyles. The pigmentation and appearance of moths are dominated by cryptic diffuse shades of brown. In this study, 82 specimens representing 26 moth species were analysed using infrared polarimetric hyperspectral imaging in the range of 0.95–2.5 µm. Contrary to previous studies, we demonstrate that since infrared light does not resolve the surface roughness, wings appear glossy and specular at longer wavelengths. Such properties provide unique reflectance spectra between species. The reflectance of the majority of our species could be explained by comprehensive models, and a complete parametrization of the spectral, polarimetric and angular optical properties was reduced to just 11 parameters with physical units. These parameters are complementary and, compared with the within-species variation, were significantly distinct between species. Counterintuitively to the aperture-limited resolution criterion, we could deduce microscopic features along the surface from their infrared properties. These features were confirmed by electron microscopy. Finally, we show how our findings could greatly enhance opportunities for remote identification of free-flying moth species, and we hypothesize that such flat specular wing targets could be expected to be sensed over considerable distances.     

The Impact of Plant Phytochemicals on the Gut Microbiota of Humans for a Balanced Life

The gastrointestinal tract of humans is a complex microbial ecosystem known as gut microbiota. The microbiota is involved in several critical physiological processes such as digestion, absorption, and related physiological functions and plays a crucial role in determining the host’s health. The habitual consumption of specific dietary components can impact beyond their nutritional benefits, altering gut microbiota diversity and function and could manipulate health. Phytochemicals are non-nutrient biologically active plant components that can modify the composition of gut microflora through selective stimulation of proliferation or inhibition of certain microbial communities in the intestine. Plants secrete these components, and they accumulate in the cell wall and cell sap compartments (body) for their development and survival. These compounds have low bioavailability and long time-retention in the intestine due to their poor absorption, resulting in beneficial impacts on gut microbiota population. Feeding diets containing phytochemicals to humans and animals may offer a path to improve the gut microbiome resulting in improved performance and/or health and wellbeing. This review discusses the effects of phytochemicals on the modulation of the gut microbiota environment and the resultant benefits to humans; however, the effect of phytochemicals on the gut microbiota of animals is also covered, in brief.     

Functionalization of Graphene Oxide Films with Au and MoOx Nanoparticles as Efficient p‐Contact Electrodes for Inverted Planar Perovskite Solar Cells

A graphene oxide (GO) film is functionalized with metal (Au) and metal‐oxide (MoO_x) nanoparticles (NPs) as a hole‐extraction layer for high‐performance inverted planar‐heterojunction perovskite solar cells (PSCs). These NPs can increase the work function of GO, which is confirmed with X‐ray photoelectron spectra, Kelvin probe force microscopy, and ultraviolet photoelectron spectra measurements. The down‐shifts of work functions lead to a decreased level of potential energy and hence increased V_oc of the PSC devices. Although the GO‐AuNP film shows rapid hole extraction and increased V_oc, a J_sc improvement is not observed because of localization of the extracted holes inside the AuNP that leads to rapid charge recombination, which is confirmed with transient photoelectric measurements. The power conversion efficiency (PCE) of the GO‐AuNP device attains 14.6%, which is comparable with that of the GO‐based device (14.4%). In contrast, the rapid hole extraction from perovskite to the GO‐MoO_x layer does not cause trapping of holes and delocalization of holes in the GO film accelerates rapid charge transfer to the indium tin oxide substrate; charge recombination in the perovskite/GO‐MoO_x interface is hence significantly retarded. The GO‐MoO_x device consequently shows significantly enhanced V_oc and J_sc, for which its device performance attains PCE of 16.7% with great reproducibility and enduring stability.     

OGHAM: On-demand global hosts for mobile ad-hoc multicast services

Recent advances in pervasive computing and wireless technologies have enabled novel multicast services anywhere, anytime, such as mobile auctions, advertisement, and e-coupons. Routing/multicast protocols in large-scale ad-hoc networks adopt two-tier infrastructures to accommodate the effectiveness of the flooding scheme and the efficiency of the tree-based scheme. In these protocols, hosts with a maximal number of neighbors are chosen as backbone hosts (BHs) to forward packets. Most likely, these BHs will be traffic concentrations or bottlenecks of the network and spend significant amount of time forwarding packets. In this paper, a distinct strategy is proposed for constructing a two-tier infrastructure in a large-scale ad-hoc network. Hosts with a minimal number of hops to the other hosts rather than those with a maximal number of neighbors will be adopted as BHs in order to obtain shorter multicast routes. The problem of determining BHs can be formulated with linear programming. BHs thus found have the advantages of shorter relay and less concentration. Besides, BHs are selected on-demand and can be globally reused for different multicast groups without flooding again. Simulation results show that the proposed protocol has shorter transmission latency, fewer control/data packets and higher receiving data packet ratios than other existing multicast protocols. Besides, the two-tier infrastructure constructed by the proposed protocol is more stable.     

Creation of Superhydrophobic Electrospun Nonwovens Fabricated from Naturally Occurring Poly(Amino Acid) Derivatives

Creation of superhydrophobic materials bio‐inspired by nature fascinates many scientists. One of the most intriguing challenges in this field is the fabrication of these materials using biopolymers from the viewpoint of green chemistry and environmental chemistry. Here, superhydrophobic and biodegradable nonwovens are constructed by electrospinning from a naturally occurring poly(amino acid), poly(γ‐glutamic acid) (γ‐PGA), modified with a hydrophobic α‐amino acid, l ‐phenylalanine. The contact angle of a water droplet on the materials is 154°, and the droplet remains stuck to the material surface even if it is inverted, clearly indicating a petal‐type superhydrophobic property. Biodegradability and post‐functionalization of the nonwovens as well as cell adhesion on the superhydrophobic materials are also evaluated. As far as we know, this is the first report on biodegradable materials exhibiting a petal‐type superhydrophobicity. The material design and processing shown here can be applied to various bioresources and such functional materials will become a new class of functional materials satisfying some of the requirements in green science.     

Simulation of Dynamic Earthquake Ruptures in Complex Geometries Using High-Order Finite Difference Methods

We develop a stable and high-order accurate finite difference method for problems in earthquake rupture dynamics in complex geometries with multiple faults. The bulk material is an isotropic elastic solid cut by pre-existing fault interfaces that accommodate relative motion of the material on the two sides. The fields across the interfaces are related through friction laws which depend on the sliding velocity, tractions acting on the interface, and state variables which evolve according to ordinary differential equations involving local fields. The method is based on summation-by-parts finite difference operators with irregular geometries handled through coordinate transforms and multi-block meshes. Boundary conditions as well as block interface conditions (whether frictional or otherwise) are enforced weakly through the simultaneous approximation term method, resulting in a provably stable discretization. The theoretical accuracy and stability results are confirmed with the method of manufactured solutions. The practical benefits of the new methodology are illustrated in a simulation of a subduction zone megathrust earthquake, a challenging application problem involving complex free-surface topography, nonplanar faults, and varying material properties.