Publications

A nuclear-targeted activity-based sensing probe for ratiometric imaging of formaldehyde reveals endogenous epigenetic contributors to the nuclear formaldehyde pool

Here, we report NucRFAP-2, a nuclear-targeted, activity-based sensing ratiometric probe for formaldehyde (FA) detection, and apply it to identify new, human disease-relevant epigenetic contributors to the nuclear FA pool.

Modeling of Electro-deposition and Mechanical Stability at Li Metal/Solid Electrolyte Interface during Plating in Solid-State Batteries

Interfacial deposition stability between Li metal and a solid electrolyte (SE) is important in preventing interfacial contact loss, mechanical fracture, and dendrite growth in Li-metal solid-state batteries (SSB). In this work, we investigate the deposition and mechanical stability at the Li metal/SE interface and its consequences (such as SE fracture and contact loss). A wide range of contributing factors are investigated, such as charge and mass transfer kinetics, the plasticity of Li metal and fracture of the SE, and the applied stack pressure. We quantify the effect of the ionic conductivity of the SE, the exchange current density of the interfacial charge-transfer reaction and SE surface roughness on the Li deposition stability at the Li metal/SE interface. We also propose a mechanical stability window for the applied stack pressure that can prevent both contact loss and SE fracture, which can be extended to other metal-electrode (such as Sodium) SSB systems.

CCDC 1533965: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

Site Selective Doping of Ultrathin Metal Dichalcogenides by Laser‐Assisted Reaction

Laser-assisted phosphorus doping is demonstrated on ultrathin transition-metal dichalcogenides (TMDCs) including n-type MoS2 and p-type WSe2 . Temporal and spatial control of the doping is achieved by varying the laser irradiation power and time, demonstrating wide tunability and high site selectivity with high stability. The laser-assisted doping method may enable a new avenue for functionalizing TMDCs for customized nanodevice applications.

Helper T cells for cytotoxic T lymphocytes need not be I region restricted

We investigated the antigenic requirements for restimulation of H-2- restricted cytolytic T lymphocytes (CTL) in vitro to determine whether H-2 I region-restricted helper T cells are required in these responses. In one set of experiments, we studied the in vitro response of (responder x nonresponder)F(1) female T cells to the male antigen H-Y. We chose to examine this response because it has been suggested that the defect in nonresponder strains is a failure of helper T cells to recognize H-Y in association with nonresponder I region determinants. However, we find that nonresponder male stimulator cells are as effective as F(1) male stimulator cells at inducing H-Y-specific CTL responses. This finding calls into question reports that secondary CTL responses to H-Y are dependent upon the activation of H-Y- specific helper T cells restricted to responder type I region determinants. In a second set of experiments, we examined the requirements for restimulation of H-2-restricted T cells specific for minor-histocompatibility antigens from long-term mixed lymphocyte cultures. These cultures were established by repeatedly restimulating cultures of specific T cells with H- 2-matched stimulator cells expressing foreign minor histocompatibility antigens. We found that H-2D-restricted T ceils, including CTL, could be restimulated with cells that were matched with the responding cells at only the D region genes. This response did not appear to result from positive allogeneic effects or from antigen processing and "representation" by responder type APC that might contaminate the cultures. Thus, we find no evidence for a requirement for I region-restricted helper T cells in these CTL responses. However, helper T cells are required because we find that CTL lines derived by limit-dilution cloning from these long-term MLC are absolutely dependent upon exogenous helper factors for growth. The most simple interpretation of these results is that the helper cells are restricted to H-2 antigens other than I region antigens or to antigens that code outside of the H-2 complex. Finally, we show that factor-dependent CTL lines must recognize their specific antigen to proliferate, even in the presence of exogenous factors. The requirement of activated CTL for antigen to proliferate provides an explanation for how specific CTL can be selectively enriched in MLC by specific antigen stimulation. Furthermore, it is at variance with reports that memory CTL or activated CTL require only interleukin 2 for restimulation.

Isotopic studies of carbohydrate metabolism in non-insulin-dependent diabetes mellitus

Isotopic techniques are required for answering many fundamental pathophysiologic questions in diabetes research. Several isolopic methods and results are critically evaluated here, along with a description of recent methodologic advances. Included is the role of hepatic glucose production (HGP) in fasting hyperglycemia, the metabolic source of HGP (gluconeogenesis vs glycogenolysis), whether HGP is substrate-driven, and the tissue location and metabolic fate of glucose disposal. Progress in the measurement of HGP, gluconeogenesis, hepatic substrate fluxes, and hepatic uridine diphosphate-glucose metabolism is described. The uses of isotope-kinetic methods in identifying sites of drug action and genes contributing to non-insulin-dependent diabetes mellitus are also noted.

Epitaxial Growth of InGaN Nanowire Arrays for Light Emitting Diodes

Significant synthetic challenges remain for the epitaxial growth of high-quality InGaN across the entire compositional range. One strategy to address these challenges has been to use the nanowire geometry because of its strain relieving properties. Here, we demonstrate the heteroepitaxial growth of In(x)Ga(1-x)N nanowire arrays (0.06 ≤ x ≤ 0.43) on c-plane sapphire (Al(2)O(3)(001)) using a halide chemical vapor deposition (HCVD) technique. Scanning electron microscopy and X-ray diffraction characterization confirmed the long-range order and epitaxy of vertically oriented nanowires. Structural characterization by transmission electron microscopy showed that single crystalline nanowires were grown in the ⟨002⟩ direction. Optical properties of InGaN nanowire arrays were investigated by absorption and photoluminescence measurements. These measurements show the tunable direct band gap properties of InGaN nanowires into the yellow-orange region of the visible spectrum. To demonstrate the utility of our HCVD method for implementation into devices, LEDs were fabricated from In(x)Ga(1-x)N nanowires epitaxially grown on p-GaN(001). Devices showed blue (x = 0.06), green (x = 0.28), and orange (x = 0.43) electroluminescence, demonstrating electrically driven color tunable emission from this p-n junction.

How penal common sense comes to europeans

This article analyzes the processes whereby a new ‘penal common sense’ aiming to criminalize poverty and thereby normalize precarious wage labor has incubated in America and is being internationalized, alongside the neoliberal economic ideology which it translates and complements in the realm of ‘justice’. Three operations are distinguished in the transatlantic diffusion of this new doxa on ‘security’: (1) the gestation and dissemination of terms, theses, and measures that converge to penalize social insecurity and its consequences; (2) their borrowing, through a work of adaptation to the national cultural idiom and state tradition, by the officials of the different receiving countries; (3) the ‘academicization’ of the categories of neoliberal understanding by pseudo-social research that serves to legitimize the bolstering of the penal state. Denunciations of ‘urban violence’ and increased surveillance of ‘problem neighborhoods’, curfews and the targeting of petty drug offenders, deregulation and privatization of criminal justice services, ‘prison works’ and ‘zero tolerance’: these mottos, notions, and policies promoted by neoconservative think-tanks in the United States and their British trading posts have spread throughout western Europe where they facilitate the transition from a social welfare to a penal management of the rising social misery. Thus one needs to extend the expression ‘Washington consensus’, commonly used to designate neoliberal measures of ‘structural adjustment’ imposed by the rulers of global finance on debtor nations, to encompass the policing and carceral management of the increased poverty and marginality that are the socio-logical consequence of these economic policies in advanced societies.

The keystone cops meet in Hilo

Le corps, le ghetto et l’État pénal

Dans cet article, l’auteur explicite son approche de l’ethnographie, de la théorie sociale et de la politique du savoir, à travers un entretien au fil duquel il démêle les liens entre ses travaux sur l’incorporation, la marginalité urbaine et l’État pénal. En retraçant son parcours intellectuel, il porte au jour les connexions pratiques et épistémologiques entre ses principaux projets de recherche, spécifie la contribution du travail de terrain à chacun d’eux, et examine les rôles des intellectuels dans les sociétés avancées à l’ère de l’hégémonie néolibérale. Renvoyant dos à dos l’empirisme de Hume et le cognitivisme néo-kantien, l’auteur défend l’usage de l’ethnographie comme instrument de rupture et de construction, souligne la puissance des compétences incarnées, et plaide pour l’impératif de réflexivité épistémique ainsi que pour la multiplication des genres textuels et des styles d’écriture afin de mieux capturer la douleur et la saveur de l’action. Dans la sphère publique, il argue que la science sociale est en mesure d’agir comme dissolvant de la doxa mais aussi comme phare éclairant les propriétés latentes et les tendances inaperçues des transformations sociales, de sorte à perturber et à élargir le débat civique.

Langmuir−Blodgett Silver Nanowire Monolayers for Molecular Sensing Using Surface-Enhanced Raman Spectroscopy

Langmuir−Blodgett technique was used to assemble monolayers (with areas over 20 cm2) of aligned silver nanowires that are ∼50 nm in diameter and 2−3 μm in length. These nanowires possess pentagonal cross-sections and pyramidal tips. They are close-packed and are aligned parallel to each other. The resulting nanowire monolayers serve as excellent substrates for surface-enhanced Raman spectroscopy (SERS) with large electromagnetic field enhancement factors (2 × 105 for thiol and 2,4-dinitrotoluene, and 2 × 109 for Rhodamine 6G) and can readily be used in ultrasensitive, molecule-specific sensing utilizing vibrational signatures.

Surface science and catalysis of ethylene hydrogenation

Surface science and catalysis have been combined over the last 15 years to study the hydrogenation of the simplest alkene, ethylene, over late-transition-metal catalysts. Ethylene hydrogenation has been used as a model reaction because it yields only one product while permitting molecular information to be gleaned on an important class of chemical reactions. Enormous progress has been achieved in this field in recent years by the application of reaction rate and surface spectroscopic studies. The role of carbon-containing overlayers covering the surface during reaction has been identified, intermediates present during reaction have been observed and detailed molecular mechanisms for this reaction can be proposed.

Recent progress in structure determination by LEED (low-energy electron diffraction)

Surface crystallography with low-energy electron diffraction (LEED) is shown to be developing fast towards solving more complex and diverse kinds of surfaces. This progress is exemplified here with solved structures in three very diverse categories: (1) metal surface reconstructions with multi-layer relaxations: (2) coadsorption of different molecules on metal surfaces; and (3) incommensurate overlayers of graphite on Pt(111). 21 refs., 4 figs.

Rapid follow-up observations of infant supernovae with the Gran Telescopio Canarias

Abstract The first few hours of a supernova (SN) contain significant information about the progenitor system. The most modern wide-field surveys that scan the sky repeatedly every few days can discover all kinds of transients in those early epochs. At such times, some progenitor footprints may be visible, elucidating critical explosion parameters and helping to distinguish between leading explosion models. A dedicated spectroscopic classification programme using the optical spectrograph OSIRIS mounted on the Gran Telescopio de Canarias was set up to try to obtain observations of supernovae (SNe) at those early epochs. With the time awarded, we obtained spectra of 10 SN candidates, which we present here. Half of them were thermonuclear SNe, while the other half were core-collapse SNe. Most (70%) were observed within the first six days of the estimated explosion, with two being captured within the first 48 hours. We present a characterization of the spectra, together with other public ancillary photometry from the Zwicky Transient Facility (ZTF) and the Asteroid Terrestrial-impact Last Alert System (ATLAS) . This project shows the need for an accompanying rapid-response spectroscopic programme for existing and future deep photometric wide-field surveys located at the right longitude to be able to trigger observations in a few hours after the discovery of the SN candidate. Both the future La Silla Southern Supernova Survey (LS4) and the Legacy Survey of Space and Time (LSST), both located in Chile, will be providing discovery and follow-up of most of the transients in the southern hemisphere. This paper demonstrates that with a rapid spectroscopic programme and stringent triggering criteria, obtaining a sample of SN with spectra within a day of the explosion is possible.

SAME but Different: Fast and High-Quality Gibbs Parameter Estimation

Gibbs sampling is a workhorse for Bayesian inference but has several limitations when used for parameter estimation, and is often much slower than non-sampling inference methods. SAME (State Augmentation for Marginal Estimation) \cite{Doucet99,Doucet02} is an approach to MAP parameter estimation which gives improved parameter estimates over direct Gibbs sampling. SAME can be viewed as cooling the posterior parameter distribution and allows annealed search for the MAP parameters, often yielding very high quality (lower loss) estimates. But it does so at the expense of additional samples per iteration and generally slower performance. On the other hand, SAME dramatically increases the parallelism in the sampling schedule, and is an excellent match for modern (SIMD) hardware. In this paper we explore the application of SAME to graphical model inference on modern hardware. We show that combining SAME with factored sample representation (or approximation) gives throughput competitive with the fastest symbolic methods, but with potentially better quality. We describe experiments on Latent Dirichlet Allocation, achieving speeds similar to the fastest reported methods (online Variational Bayes) and lower cross-validated loss than other LDA implementations. The method is simple to implement and should be applicable to many other models.

High-performance liquid chromatography separation media based on functional polymers containing phenolic hydroxyls

CCDC 1583541: Experimental Crystal Structure Determination

THE FUTURE OF APPLIED POLYMER SCIENCE