A perspective on the role of uncertainty in sustainability science and engineering.

The Trans-Atlantic Research and Development Interchange on Sustainability Workshop (TARDIS) is a meeting on scientific topics related to sustainability. The 2019 workshop theme was "On the Role of Uncertainty in Managing the Earth for Global Sustainability." This paper presents the perspectives on this topic derived from talks and discussions at the 2019 TARDIS workshop. There are four kinds of uncertainties encountered in sustainability ranging from clear enough futures to true surprises. The current state-of-the-art in assessing and mitigating these uncertainties is discussed.

Pathway to the piezoelectronic transduction logic device.

The piezoelectronic transistor (PET) has been proposed as a transduction device not subject to the voltage limits of field-effect transistors. The PET transduces voltage to stress, activating a facile insulator-metal transition, thereby achieving multigigahertz switching speeds, as predicted by modeling, at lower power than the comparable generation field effect transistor (FET). Here, the fabrication and measurement of the first physical PET devices are reported, showing both on/off switching and cycling. The results demonstrate the realization of a stress-based transduction principle, representing the early steps on a developmental pathway to PET technology with potential to contribute to the IT industry.

Analysis of parahydrogen polarized spin system in low magnetic fields.

Nuclear magnetic resonance (NMR) spectra of spin systems polarized either thermally or by parahydrogen exhibit strikingly different field dependencies. Thermally polarized spin systems show the well-known roof effect, observed when reducing magnetic field strengths which precludes the independent determination of chemical shift differences and J-coupling constants at low-fields. Quantum mechanical analysis of the NMR spectra with respect to polarization method, pulsed state preparation, and transition probabilities reveals that spectra of parahydrogen polarized systems feature an "inverse roof effect" in the regime where the chemical shift difference δν is smaller than J. This inverse roof effect allows for the extraction of both J-coupling and chemical shift information down to very low fields. Based on a two-spin system, the observed non-linear magnetic field dependence of the splitting of spectral lines is predicted. We develop a general solution for the steady state density matrix of a parahydrogen polarized three-spin system including a heteronucleus which allows explaining experimentally observed (1)H spectra. The analysis of three-spin density matrix illustrates two pathways for an efficient polarization transfer from parahydrogen to (13)C nuclei. Examination of the experimental data facilitates the extraction of all relevant NMR parameters using single-scan, high-resolution (1)H and (13)C NMR spectroscopy at low fields at a fraction of the cost associated with cryogenically cooled high-field NMR spectrometers.

Long-lived heteronuclear spin-singlet states in liquids at a zero magnetic field.

We report an observation of long-lived spin-singlet states in a 13C-1H spin pair in a zero magnetic field. In 13C-labeled formic acid, we observe spin-singlet lifetimes as long as 37 s, about a factor of 3 longer than the T1 lifetime of dipole polarization in the triplet state. In contrast to common high-field experiments, the observed coherence is a singlet-triplet coherence with a lifetime T2 longer than the T1 lifetime of dipole polarization in the triplet manifold. Moreover, we demonstrate that heteronuclear singlet states formed between a 1H and a 13C nucleus can exhibit longer lifetimes than the respective triplet states even in the presence of additional spins that couple to the spin pair of interest. Although long-lived homonuclear spin-singlet states have been extensively studied, this is the first experimental observation of analogous singlet states in heteronuclear spin pairs.

Composite and shaped pulses for efficient and robust pumping of disconnected eigenstates in magnetic resonance.

Hyperpolarization methods, which can enhance nuclear spin signals by orders of magnitude, open up important new opportunities in magnetic resonance. However, many of these applications are limited by spin lattice relaxation, which typically destroys the hyperpolarization in seconds. Significant lifetime enhancements have been found with "disconnected eigenstates" such as the singlet state between a pair of nearly equivalent spins, or the "singlet-singlet" state involving two pairs of chemically equivalent spins; the challenge is to populate these states (for example, from thermal equilibrium magnetization or hyperpolarization) and to later recall the population into observable signal. Existing methods for populating these states are limited by either excess energy dissipation or high sensitivity to inhomogeneities. Here we overcome the limitations by extending recent work using continuous-wave irradiation to include composite and adiabatic pulse excitations. Traditional composite and adiabatic pulses fail completely in this problem because the interactions driving the transitions are fundamentally different, but the new shapes we introduce can move population between accessible and disconnected eigenstates over a wide range of radio-frequency (RF) amplitudes and offsets while depositing insignificant amounts of power.

Giant piezoresistive on/off ratios in rare-earth chalcogenide thin films enabling nanomechanical switching.

Sophisticated microelectromechanical systems for device and sensor applications have flourished in the past decade. These devices exploit piezoelectric, capacitive, and piezoresistive effects, and coupling between them. However, high-performance piezoresistivity (as defined by on/off ratio) has primarily been observed in macroscopic single crystals. In this Letter, we show for the first time that rare-earth monochalcogenides in thin film form can modulate a current by more than 1000 times due to a pressure-induced insulator to metal transition. Furthermore, films as thin as 8 nm show a piezoresistive response. The combination of high performance and scalability make these promising candidates for nanoscale applications, such as the recently proposed piezoelectronic transistor (PET). The PET would mechanically couple a piezoelectric thin film with a piezoresistive switching layer, potentially scaling to higher speeds and lower powers than today's complementary metal-oxide-semiconductor technology.

Near-zero-field nuclear magnetic resonance.

We investigate nuclear magnetic resonance (NMR) in near zero field, where the Zeeman interaction can be treated as a perturbation to the electron mediated scalar interaction (J coupling). This is in stark contrast to the high-field case, where heteronuclear J couplings are normally treated as a small perturbation. We show that the presence of very small magnetic fields results in splitting of the zero-field NMR lines, imparting considerable additional information to the pure zero-field spectra. Experimental results are in good agreement with first-order perturbation theory and with full numerical simulation when perturbation theory breaks down. We present simple rules for understanding the splitting patterns in near-zero-field NMR, which can be applied to molecules with nontrivial spectra.

The effect of pathogen reduction technology (Mirasol) on platelet quality when treated in additive solution with low plasma carryover.

BACKGROUND AND OBJECTIVES: Pathogen reduction technologies (PRT) for platelets are now compatible with both plasma and platelet additive solutions (PAS). The aim of this study was to examine the effect of PRT on the platelet storage lesion, in the presence of PAS with low plasma carryover. MATERIALS AND METHODS: PRT-treated (Mirasol) and untreated buffy coat-derived platelet concentrates prepared in 28% plasma/PAS-IIIM were evaluated using in vitro cell quality parameters on days 1, 2, 5, and 7 post-collection. RESULTS: At day 5, there were no significant differences between control and PRT treated platelets for swirl, viability, pO(2) , pCO(2) , mean platelet volume and adenosine diphosphate-induced aggregation. PRT treatment did not affect the functional integrity of the mitochondria. However, PRT resulted in a decrease in pH and enhancement of platelet glycolysis and activation, evidenced by increased glucose consumption and lactate production rates, increased expression of CD62P, CD63, annexin V staining and increased secretion of cytokines (P < 0.05). Hypotonic shock response and aggregation in response to collagen were also significantly reduced in PRT treated platelets (P < 0.05). CONCLUSION: Despite the observed differences in platelet metabolism and activation observed following PRT treatment in PAS and low plasma carryover, the results suggest that treatment and storage of platelets in PAS is no more detrimental to platelets than treatment and storage in plasma.

Cryopreservation of buffy-coat-derived platelet concentrates in dimethyl sulfoxide and platelet additive solution.

Platelets prepared in plasma can be frozen in 6% dimethyl sulfoxide (Me(2)SO) and stored for extended periods at -80°C. The aim of this study was to reduce the plasma present in the cryopreserved product, by substituting plasma with platelet additive solution (PAS; SSP+), whilst maintaining in vitro platelet quality. Buffy coat-derived pooled leukoreduced platelet concentrates were frozen in a mixture of SSP+, plasma and 6% Me(2)SO. The platelets were concentrated, to avoid post-thaw washing, and frozen at -80°C. The cryopreserved platelet units (n=9) were rapidly thawed at 37°C, reconstituted in 50% SSP+/plasma and stored at 22°C. Platelet recovery and quality were examined 1 and 24h post-thaw and compared to the pre-freeze samples. Upon thawing, platelet recovery ranged from 60% to 80%. However, there were differences between frozen and liquid-stored platelets, including a reduction in aggregation in response to ADP and collagen; increased CD62P expression; decreased viability; increased apoptosis and some loss of mitochondrial membrane integrity. Some recovery of these parameters was detected at 24h post-thaw, indicating an extended shelf-life may be possible. The data suggests that freezing platelets in 6% Me(2)SO and additive solution produces acceptable in vitro platelet quality.

Antifungal proteins: targets, mechanisms and prospective applications.

All organisms have evolved several defence systems in order to protect themselves against bacteria, fungi and viruses. Higher organisms have developed a complex network of humoral and cellular responses, called adaptive immunity. A second defence system, innate immunity, was discovered in the early 1980s, consisting of small cationic peptides with a broad antimicrobial spectrum. These proteins act immediately at sites of infection or inflammation. The production of proteins with antimicrobial activity was not limited to higher organisms but was also found in insects, plants and microorganisms. During the last 2 decades a broad range of proteins with very different structural features have been isolated and characterised from differing organisms ranging from bacteria to human beings. Over 500 cationic membrane-acting proteins with antimicrobial and antifungal activities have been identified to date. Apart from these proteins, a very large number of antifungal proteins active on the fungal cell wall, on enzymes of the cell wall synthesis machinery, the plasma membrane and on intracellular targets have been characterised.

The antifungal protein from Aspergillus giganteus causes membrane permeabilization.

We investigated the inhibitory effects of the antifungal protein (AFP) from Aspergillus giganteus on the growth of several filamentous fungi. For this purpose, the MICs of AFP were determined and ranged from 0.1 micro g/ml for Fusarium oxysporum to 200 micro g/ml for Aspergillus nidulans. The antifungal activity of AFP was diminished in the presence of cations. We were able to show that incubation of AFP-sensitive fungi with the protein resulted in membrane permeabilization using an assay based on the uptake of the fluorescent dye SYTOX Green. No permeabilization by AFP could be detected at concentrations below the species-specific MIC. Furthermore, AFP-induced permeabilization could readily be detected after 5 min of incubation. Localization experiments with fluorescein isothiocyanate-labeled AFP and immunofluorescence staining with an AFP-specific antibody supported the observation that the protein interacts with membranes. After treatment of AFP-sensitive fungi with AFP, the protein was localized at the plasma membrane, whereas it was mainly detected inside the cells of AFP-resistant fungi. We conclude from these data that the growth-inhibitory effect of AFP is caused by permeabilization of the fungal membranes.