Power output variations of co-located offshore wind turbines and wave energy converters in California

The electric power generation of co-located offshore wind turbines and wave energy converters along the California coast is investigated. Meteorological wind and wave data from the National Buoy Data Center were used to estimate the hourly power output from offshore wind turbines and wave energy converters at the sites of the buoys. The data set from 12 buoys consists of over 1,000,000 h of simultaneous hourly mean wind and wave measurements. At the buoys, offshore wind farms would have capacity factors ranging from 30% to 50%, and wave farms would have capacity factors ranging from 22% to 29%. An analysis of the power output indicates that co-located offshore wind and wave energy farms generate less variable power output than a wind or wave farm operating alone. The reduction in variability results from the low temporal correlation of the resources and occurs on all time scales. Aggregate power from a co-located wind and wave farm achieves reductions in variability equivalent to aggregating power from two offshore wind farms approximately 500 km apart or two wave farms approximately 800 km apart. Combined wind and wave farms in California would have less than 100 h of no power output per year, compared to over 1000 h for offshore wind or over 200 h for wave farms alone. Ten offshore farms of wind, wave, or both modeled in the California power system would have capacity factors during the summer ranging from 21% (all wave) to 36% (all wind) with combined wind and wave farms between 21% and 36%. The capacity credits for these farms range from 16% to 24% with some combined wind and wave farms achieving capacity credits equal to or greater than a 100% wind farm because of their reduction in power output variability.     

Dynamic mechanical analysis of magnetic tapes at ultra‐low frequencies

A custom, ultra‐low frequency, dynamic mechanical analyzer (ULDMA) has been developed to study the correlated effects of temperature and frequency on the viscoelastic behavior of magnetic tapes. It has been used to acquire data needed for the development of future magnetic tapes that require an archival life of up to 100 years. A range of elevated temperatures is used to simulate real‐world storage environments, which enables the investigation of how the viscoelastic characteristics of tape samples influence the extent to which the tape deforms. The experiments and subsequent analysis examine the influence of the molecular structure on the viscoelasticity of magnetic tapes. Experiments were performed on a variety of magnetic tapes, including poly(ethylene terephthalate) (PET), poly(ethylene naphthalate) (PEN), metalized PET (M‐PET), and metalized Spaltan (M‐SPA). Additional experiments examined PEN and PET substrates by removing the front and back magnetic layers from the tape sample. Because of the viscoelastic behavior of the tapes, a time delay was present between the strain and stress signals, which was determined using a Fourier transform program. The elastic modulus (E), storage modulus (E′), loss modulus (E″), and loss tangent (tan δ) were obtained from the time delay for each of the ULDMA experiments at 25, 50, and 70°C over the frequency range of 0.0100–0.0667 Hz. Plots of these mechanical characteristics demonstrate the ability of frequency and temperature to affect trends associated with mechanical and thermal properties. Finally, some samples displayed an initial relaxation during the ULDMA experiments, which, when modeled using Maxwell's viscoelastic model, provided an insight into the relaxation characteristics of the samples. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

The Intertwining of Transposable Elements and Non-Coding RNAs

Growing evidence shows a close association of transposable elements (TE) with non-coding RNAs (ncRNA), and a significant number of small ncRNAs originate from TEs. Further, ncRNAs linked with TE sequences participate in a wide-range of regulatory functions. Alu elements in particular are critical players in gene regulation and molecular pathways. Alu sequences embedded in both long non-coding RNAs (lncRNA) and mRNAs form the basis of targeted mRNA decay via short imperfect base-pairing. Imperfect pairing is prominent in most ncRNA/target RNA interactions and found throughout all biological kingdoms. The piRNA-Piwi complex is multifunctional, but plays a major role in protection against invasion by transposons. This is an RNA-based genetic immune system similar to the one found in prokaryotes, the CRISPR system. Thousands of long intergenic non-coding RNAs (lincRNAs) are associated with endogenous retrovirus LTR transposable elements in human cells. These TEs can provide regulatory signals for lincRNA genes. A surprisingly large number of long circular ncRNAs have been discovered in human fibroblasts. These serve as “sponges” for miRNAs. Alu sequences, encoded in introns that flank exons are proposed to participate in RNA circularization via Alu/Alu base-pairing. Diseases are increasingly found to have a TE/ncRNA etiology. A single point mutation in a SINE/Alu sequence in a human long non-coding RNA leads to brainstem atrophy and death. On the other hand, genomic clusters of repeat sequences as well as lncRNAs function in epigenetic regulation. Some clusters are unstable, which can lead to formation of diseases such as facioscapulohumeral muscular dystrophy. The future may hold more surprises regarding diseases associated with ncRNAs andTEs.     

Elastomeric skin selection for a fluid‐filled artificial fingertip

Biomimetic fingertips for robots and prostheses need to combine compliant grip and tactile sensing with robustness in diverse environments. We have evaluated materials for use in a compliant, fluid‐filled artificial fingertip that incorporates multimodal sensing of contact, texture and thermal properties. A variety of silicone elastomers were tested for hardness, wear‐rate, and stress–strain relationships. Diffusion rates of several aqueous and nonaqueous solvents through elastomeric membranes were analyzed to ensure that the sensor could maintain proper fluid volume and function for an extended period. A solution of sodium bromide in poly(ethylene glycol)‐200 and water combined with a Silastic S silicone elastomeric cosmesis produced a stable and robust solution. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

High molecular weight copolymers of vinylferrocene and 3-phenyl[5]ferrocenophane-1,5-dimethylene with various N-substituted maleimides

Two series of ferrocene-containing polymers have been synthesized from various N-substituted maleimides with 3-phenyl[5]ferrocenophane-1,5-dimethylene (3A–C) or vinylferrocene (4A–C). These copolymers exhibit high molecular weights and 4A–C formed free standing films. Electrochemical studies with copolymers 3A–C and 4A–C in dimethylacetamide show chemical reversibility for all of the materials but only copolymers 4A–C show electrochemical reversibility. These copolymers were also electrochemically deposited from methylene chloride onto a platinum electrode to form chemically modified electrodes (CMEs). The CMEs show desorption of the ferrocene polymers in acetonitrile solutions but exhibited good stability in aqueous solution. The thermal stabilities of the copolymers 4A–C are typical for a ferrocene containing polymer with 10% weight loss occurring at ca. 385 °C. Copolymers 3A–C exhibit higher thermal stabilities with 10% weight loss at 438 °C. Differential scanning calorimetry measurements of the copolymers showed melt transitions just before the onset of thermal decomposition.     

Nonselective debridement and antimicrobial cleansing of a venting ductal breast carcinoma

Supracondylar femur fractures above a total knee replacement are rare injuries that may be challenging to treat. We present a case of an elderly woman whose supracondylar femur fracture was not deemed amenable to conventional treatment. This patient underwent fixation of her femur fracture above a total knee replacement using an Ilizarov external fixator. The fixator was removed at 10 weeks, at which time the fracture was solidly healed. At the most recent follow-up, the patient is 19 months postinjury. She is fully weight bearing without walking aids and has a knee range of motion of 0 degree to 110 degrees.     

Substituent Effect on the Reactivity of Alkylated Triphenyl Phosphorothionates in Oil Solution in the Presence of Iron Particles

The effect of the substituent attached to the phenyl rings on the reactivity of alkylated triphenyl phosphorothionates (t-butyl TPPT (b-TPPT) and p-nonyl TPPT (n-TPPT)) in oil solution at high temperature (423 and 473 K) was investigated by means of Fourier-transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The FT-IR and NMR results show that the alkylated TPPTs were highly thermally stable and did not completely decompose in oil, even upon heating at 423 K for 168 h and at 473 K for 72 h, with and without steel filings and iron particles (both metallic iron and iron oxide particles). The reaction of alkylated TPPTs was found to start with the scission of the P=S bond to yield alkylated triphenyl phosphate. The kinetics of the thermo-oxidative reaction was slower when steel filings and iron particles were added to the oil solutions during the heating experiments. The reactivity of the unsubstituted molecule (TPPT) was higher than that of alkylated TPPTs at 423 K, while at 473 K TPPT and n-TPPT were more reactive than b-TPPT. In the case of the experiments performed at 473 K in the presence of steel filings or metallic iron or iron oxide particles, the reactivity of the alkylated TPPT molecules decreased with the length of the alkyl chain bound to the phenyl rings. The XPS results show that a reaction layer consisting of carbon, oxygen, phosphorus and iron was formed on the 100Cr6 steel filings immersed for 72 h in oil solutions containing alkylated TPPTs and heated at 473 K. Sulphur was neither detected on the surface nor in the composition vs depth profile. During the heating experiments, the base oil (PAO) was oxidized. At 423 K, the alkylated TPPTs had a strong antioxidant effect, which was found to be more pronounced upon increasing the length of the alkyl chain bound to the phenyl rings. At 473 K, the TPPTs did not inhibit the oxidation of the base oil as effectively as at 423 K.     

The Statutory Homelessness System in England: A Fair and Effective Rights-Based Model?

The statutory homelessness system, first established by the Housing (Homeless Persons) Act 1977, is an important but frequently criticised element of the British welfare state. Drawing upon a survey of 2053 ‘statutorily homeless’ families in England, this paper applies a utility-maximising conceptual framework to demonstrate that (a) the statutory homelessness system is on the whole ‘fair’ with respect to the housing needs that it addresses, and (b) ‘effective’, in that it can bring about significant net gains in the welfare of those households its assists. These encouraging findings are relevant not only to current concerns about the future direction of homelessness policy in England, but also to policy debates in many countries across the developed world where there are calls to develop a ‘rights-based’ approach to addressing homelessness.