Design of an integrated sensor for in vivo simultaneous electrocontractile cardiac mapping

While there is extensive mapping of the spread of electrical activity in the heart, there have been no measurements of electrical and localized mechanical, or contractile, activity. Yet the development of effective treatments for diseases like chronic heart failure and cardiac hypertrophy depend on the ability to quantify improvements in electrocontractile function. In this paper, we present a sensor that is capable of making simultaneous, electrocontractile measurements. Its small size facilitates placement in multiple myocardial sites for multichannel studies. Semiconductor strain gages are used for force sensing, and Ag/AgCl-plated tungsten electrodes act as electrogram sensors. The sensor contains electronics on-board, including instrumentation amplifiers and a microprocessor for data sampling and analog-to-digital conversion. Each sensor can accurately detect 0-245+/-5 mV in two electrogram channels with a sensitivity of 0.96+/-0.2 mV/step and less than 2% error, and 0-144+/-29 g of contractile force with a sensitivity of 0.56+/-0.11 g/step in the analog-to-digital conversion and less than 6% error. The sensor has been tested in vivo in open-chest rabbit and pig mapping studies. These studies indicated that the average peak-to-peak contractile force at the apex is smaller in the rabbit than the pig (13.3 versus 40.3 g), that the average peak-to-peak contractile force in the pig is smaller near the base than near the apex (31.3 versus 40.3 g), and that contractile force is visibly decreased during ventricular fibrillation compared to normal sinus rhythm.     

Broadband,High‐Speed,and Large‐Amplitude Dynamic Optical Switching with Yttrium‐Doped Cadmium Oxide

Transparent conducting oxides, such as doped indium oxide, zinc oxide, and cadmium oxide (CdO), have recently attracted attention as tailorable materials for applications in nanophotonic and plasmonic devices such as low‐loss modulators and all‐optical switches due to their tunable optical properties, fast optical response, and low losses. In this work, optically induced extraordinarily large reflection changes (up to 135%) are demonstrated in bulk CdO films in the mid‐infrared wavelength range close to the epsilon near zero (ENZ) point. To develop a better understanding of how doping level affects the static and dynamic optical properties of CdO, the evolution of the optical properties with yttrium (Y) doping is investigated. An increase in the metallicity and a blueshift of the ENZ point with increasing Y‐concentrations is observed. Broadband all‐optical switching from near‐infrared to mid‐infrared wavelengths is demonstrated. The major photoexcited carrier relaxation mechanisms in CdO are identified and it is shown that the relaxation times can be significantly reduced by increasing the dopant concentration in the film. This work could pave the way to practical dynamic and passive optical and plasmonic devices with doped CdO spanning wavelengths from the ultraviolet to the mid‐infrared region.     

Theoretical and experimental study of the second-order polarizabilities of Schiff''s bases for nonlinear optical applications

A series of twenty-four Schiff's bases was synthesized and nonresonant static molecular second order polarizabilities (β) of these compounds were theoretically calculated and compared with experimental values. The computational method employed obtained: (a) values of polarization versus static electric fields using a semiempirical Hamiltonian; (b) all tensor elements of β by performing polynomial fits of the former data, within the finite-field approach. The experimental values were obtained using a modified electric field induced second harmonic generation (EFISH) experiment with 1,4-dioxane as the solvent. The measured quantities were the projection of β on μ (the permanent dipole moment), relative to MNA (2-methyl-4-nitroaniline). The correlation between the predicted static molecular quantities and their corresponding experimental values was 0.95 (based on a simple least-squares regression forced through the origin). A factor of 8.7 ± 0.3 was determined to be the adjustment parameter for Schiff's bases to account for the solvent and dispersion effects at the fundamental wavelength of 1064 nm.     

A High-Voltage,Dendrite-Free,and Durable Zn–Graphite Battery

The intrinsic advantages of metallic Zn, like high theoretical capacity (820 mAh g⁻¹), high abundance, low toxicity, and high safety have driven the recent booming development of rechargeable Zn batteries. However, the lack of high-voltage electrolyte and cathode materials restricts the cell voltage mostly to below 2 V. Moreover, dendrite formation and the poor rechargeability of the Zn anode hinder the long-term operation of Zn batteries. Here a high-voltage and durable Zn–graphite battery, which is enabled by a LiPF₆-containing hybrid electrolyte, is reported. The presence of LiPF₆ efficiently suppresses the anodic oxidation of Zn electrolyte and leads to a super-wide electrochemical stability window of 4 V (vs Zn/Zn²⁺). Both dendrite-free Zn plating/stripping and reversible dual-anion intercalation into the graphite cathode are realized in the hybrid electrolyte. The resultant Zn–graphite battery performs stably at a high voltage of 2.8 V with a record midpoint discharge voltage of 2.2 V. After 2000 cycles at a high charge–discharge rate, high capacity retention of 97.5% is achieved with ≈100% Coulombic efficiency.     

Multi-Carrier Generation in Organic-Passivated Black Silicon Solar Cells with Industrially Feasible Processes

The innate inverse Auger effect within bulk silicon can result in multiple carrier generation. Observation of this effect is reliant upon low high-energy photon reflectance and high-quality surface passivation. In the photovoltaics industry, metal-assisted chemical etching (MACE) to afford black silicon (b-Si) can provide a low high-energy photon reflectance. However, an industrially feasible and cheaper technology to conformally passivate the outer-shell defects of these nanowires is currently lacking. Here, a technology is introduced to infiltrate black silicon nanopores with a simple and vacuum-free organic passivation layer that affords millisecond-level minority carrier lifetimes and matches perfectly with existing solution-based processing of the MACE black silicon. Advancements such as the demonstration of an excellent passivation effect whilst also being low reflectance provide a new technological route for inverse Auger multiple carrier generation and an industrially feasible technical scheme for the development of the MACE b-Si solar cells.     

Brown Superfund Basic research Program: a multistakeholder partnership addresses real-world problems in contaminated communities

The NIEHS funds several basic and applied research programs, many of which also require research translation or outreach. This paper reports on a project by the Brown University Superfund Basic Research Program (SBRP), in which outreach and research translation teams collaborated with state regulatory agency personnel and community activists on a legislative initiative to mitigate the financial impacts of living in a contaminated community. The Environmentally Compromised Home Ownership (ECHO) program makes home equity loans of up to $25,000 available to qualified applicants. This collaboration provides a case study in community engagement and demonstrates how research translation and outreach activities that are clearly differentiated yet well-integrated can improve a suite of basic and applied research. Although engaging diverse constituencies can be difficult community-engaged translation and outreach have the potential to make research findings more useful to communities, address some of the social impacts of contamination, and empower stakeholders to pursue their individual and collectively held goals for remediation. The NIEHS has recently renewed its commitment to community-engaged research and advocacy, making this an optimal time to reflect on how basic research programs that engage stakeholders through research translation and outreach can add value to the overall research enterprise.     

In vitro comparisons between Carica papaya and pancreatic lipases during test meal lipolysis: Potential use of CPL in enzyme replacement therapy

High levels of lipase activity are known to occur in Carica papaya latex, and this activity is being used in some biotechnological applications. The lipolytic activity of C. papaya lipase (CPL) on dietary triacylglycerols (TAG) has not yet been studied. Hence, the aim of this study was to characterise the specific activity of CPL on dietary TAG present in a crude preparation. Also, we have determined its stability during the lipolysis of a test meal at various pH values mimicking those occurring in the gastro-intestinal tract, with or without bile, and have compared these properties with those of porcine pancreatic extract (PPE) and human pancreatic lipase (HPL). CPL showed maximum stability at pH 6.0, both with and without bile. Some residual activity was still observed at pH 2 (20%), whereas the pancreatic lipases tested were immediately completely inactivated at this pH. In the absence of bile, the highest specific activities were measured at pH 6 in the case of CPL, PPE and HPL. Adding bile slightly decreased the CPL activity in the 4–6 pH range, thus shifting the optimum CPL activity to pH 7, where the presence of bile had no effect. Lipolysis levels decreased with the pH, but CPL was still more active than PPE at pH 5 on a relative basis. These results suggest that CPL might be a promising candidate for use as a therapeutic tool on patients with pancreatic exocrine insufficiency.     

Evaluation of toughness in AISI 4340 alloy steel austenitized at low and high temperatures

It has been reported for as-quenched AISI 4340 steel that high temperature austenitizing treatments at 1200°C, instead of conventional heat-treatment at 870°C, result in a two-foldincrease in fracture toughness,K _Ic, but adecrease in Charpy impact energy. This paper seeks to find an explanation for this discrepancy in Charpy and fracture toughness data in terms of the difference betweenK _Ic and impact tests. It is shown that the observed behavior is independent of shear lip energy and strain rate effects, but can be rationalized in terms of the differing response of the structure produced by each austenitizing treatment to the influence of notch root radius on toughness. The microstructural factors which affect this behavior are discussed. Based on these and other observations, it is considered that the use of high temperature austenitizing be questioned as a practical heat-treatment procedure for ultrahigh strength, low alloy steels. Finally, it is suggested that evaluation of material toughness should not be based solely onK _Ic or Charpy impact energy values alone; both sharp crack fracture toughness and rounded notch impact energy tests are required. formerly with Effects Technology, Inc., Santa Barbara, CA     

Linking phosphorus sequestration to carbon humification in wetland soils by 31P and 13C NMR spectroscopy

Phosphorus sequestration in wetland soils is a prerequisite for long-term maintenance of water quality in downstream aquatic systems, but can be compromised if phosphorus is released following changes in nutrient status or hydrological regimen. The association of phosphorus with relatively refractory natural organic matter (e.g., humic substances) might protect soil phosphorus from such changes. Here we used hydrofluoric acid (HF) pretreatment to remove phosphorus associated with metals or anionic sorption sites, allowing us to isolate a pool of phosphorus associated with the soil organic fraction. Solution (31)P and solid state (13)C NMR spectra for wetland soils were acquired before and after hydrofluoric acid pretreatment to assess quantitatively and qualitatively the changes in phosphorus and carbon functional groups. Organic phosphorus was largely unaffected by HF treatment in soils dominated by refractory alkyl and aromatic carbon groups, indicating association of organic phosphorus with stable, humified soil organic matter. Conversely, a considerable decrease in organic phosphorus following HF pretreatment was detected in soils where O-alkyl groups represented the major fraction of the soil carbon. These correlations suggest that HF treatment can be used as a method to distinguish phosphorus fractions that are bound to the inorganic soil components from those fractions that are stabilized by incorporation into soil organic matter.     

Effects of pectinolytic yeast on the microbial composition and spoilage of olive fermentations

This study resulted in the identification of pectinolytic yeasts in directly brined Sicilian-style green olive fermentations and examination of the influence of those yeasts on the microbial composition and quality of fermented olives. Firstly, defective olives processed in Northern California from 2007 to 2008 and characterized by high levels of mesocarp tissue degradation were found to contain distinct yeast and bacterial populations according to DNA sequence-based analyses. Strains of (pectinolytic) Saccharomyces cerevisiae, Pichia manshurica, Pichia kudriavzevii, and Candida boidinii isolated from directly brined olives were then inoculated into laboratory-scale olive fermentations to quantify the effects of individual yeast strains on the olives. The pH, titratable acidity, and numbers of lactic acid bacteria (LAB) and yeasts varied between the fermentations and fermentations inoculated with P. kudriavzevii and C. boidinii promoted the development of LAB populations. Olive tissue structural integrity declined significantly within 30, 74, and 192 days after the inoculation of pectinolytic S. cerevisiae, P. manshurica and C. boidinii, respectively. In comparison, tissue integrity of olives in control fermentations remained intact although pectinolytic yeasts were present. Notably, pectinolytic yeasts were not found in fermentations inoculated with (non-pectinolytic) P. kudriavzevii and olives exposed to a 1:1 ratio of P. kudriavzevii and P. manshurica exhibited no significant tissue defects. This study showed that pectinolytic yeast are important components of directly brined green olive fermentations and damage caused by pectinolytic yeasts might be prevented by other microbial colonists of the olives.