Liquid metal nanoparticles that are mechanically sintered at and below room temperature are introduced. This material can be sintered globally on large areas of entire deposits or locally to create liquid traces within deposits. The metallic nanoparticles are fabricated by dispersing a liquid metal in a carrier solvent via sonication. The resulting dispersion is compatible with inkjet printing, a process not applicable to the bulk liquid metal in air.

In this paper, a direct writing method for gallium‐indium alloys is presented. The relationships between nozzle inner diameter, standoff distance, flow rate, and the resulting trace geometry are demonstrated. The interaction between the gallium oxide layer and the substrate is critically important in understanding the printing behavior of the liquid metal. The difference between receding and advancing contact angles demonstrates that the adhesion of the oxide layer to the substrate surface is stronger than the wetting of the surface by the gallium‐indium alloy. This further demonstrates why free‐standing structures such as the traces described herein can be realized. In addition to the basic characterization of the direct writing process, a design algorithm that is generalizable to a range of trace geometries is developed. This method is applied to the fabrication of an elastomer‐encapsulated strain gauge that displays an approximately linear behavior through 50% strain with a gauge factor of 1.5.

Although mammalian long non-coding (lnc)RNAs are best known for modulating transcription, their post-transcriptional influence on mRNA splicing, stability and translation is emerging. Here we report a post-translational function for the lncRNA HOTAIR as an inducer of ubiquitin-mediated proteolysis. HOTAIR associates with E3 ubiquitin ligases bearing RNA-binding domains, Dzip3 and Mex3b, as well as with their respective ubiquitination substrates, Ataxin-1 and Snurportin-1. In this manner, HOTAIR facilitates the ubiquitination of Ataxin-1 by Dzip3 and Snurportin-1 by Mex3b in cells and in vitro, and accelerates their degradation. HOTAIR levels are highly upregulated in senescent cells, causing rapid decay of targets Ataxin-1 and Snurportin-1, and preventing premature senescence. These results uncover a role for a lncRNA, HOTAIR, as a platform for protein ubiquitination.

Post-transcriptional gene regulation is robustly regulated by RNA-binding proteins (RBPs). Here we describe the collection of RNAs regulated by AUF1 (AU-binding factor 1), an RBP linked to cancer, inflammation and aging. Photoactivatable ribonucleoside-enhanced crosslinking and immunoprecipitation (PAR-CLIP) analysis reveals that AUF1 primarily recognizes U-/GU-rich sequences in mRNAs and noncoding RNAs and influences target transcript fate in three main directions. First, AUF1 lowers the steady-state levels of numerous target RNAs, including long noncoding RNA NEAT1, in turn affecting the organization of nuclear paraspeckles. Second, AUF1 does not change the abundance of many target RNAs, but ribosome profiling reveals that AUF1 promotes the translation of numerous mRNAs in this group. Third, AUF1 unexpectedly enhances the steady-state levels of several target mRNAs encoding DNA-maintenance proteins. Through its actions on target RNAs, AUF1 preserves genomic integrity, in agreement with the AUF1-elicited prevention of premature cellular senescence.

Soft, flexible, and stretchable electronics are needed to transmit power and information, and track dynamic poses in next-generation wearables, soft robots, and biocompatible devices. Liquid metal has emerged as a promising material for these applications due to its high conductivity and liquid phase state at room temperature; however, surface oxidation of liquid metal gives it unique behaviors that are often incompatible with scalable manufacturing techniques. This paper reports a rapid and scalable approach to fabricate soft and flexible electronics composed of liquid metal. Compared to other liquid metal patterning approaches, this approach has the advantages of compatibility with a variety of substrates, ease of scalability, and efficiency through automated processes. Nonconductive liquid metal nanoparticle films are sintered into electrically conductive patterns by use of a focused laser beam to rupture and ablate particle oxide shells, and allow their liquid metal cores to escape and coalesce. The laser sintering phenomenon is investigated through comparison with focused ion beam sintering and by studying the effects of thermal propagation in sintered films. The effects of laser fluence, nanoparticle size, film thickness, and substrate material on resistance of the sintered films are evaluated. Several devices are fabricated to demonstrate the electrical stability of laser-patterned liquid metal traces under flexing, multilayer circuits, and intricately patterned circuits. This work merges the precision, consistency, and speed of laser manufacturing with the material benefits of liquid conductors on elastic substrates to demonstrate decisive progress toward commercial-scale manufacturing of soft electronics.

Experiments using anterograde and retrograde tracing techniques have been used to identify projections to and from the region of mouse SmI cortex which contains the posteromedial barrel subfield (PMBSF, Woolsey and Van der Loos, '70). Microinjections containing horseradish peroxidase (HRP) and tritiated amino acids were placed unilaterally into the topographic center of the PMBSF. Brains were perfuse-fixed and frozen sectioned. All sections were reacted for HRP and alternate sections were autoradiographed. Examination of sections cut tangential to the pial surface in the region of the injection site showed that diffusion of the injection was limited to cortex above and below the PMBSF in layer IV (i.e., PMBSF cortex). A "column" of HRP reaction product and developed silver grains was present in ipsilateral cortical area 40, in the face area of SmII. HRP positive cell bodies were mainly in layers I11 and VI of this "column." A similar "column" was present in ipsilateral cortical area 6, in a region which in the rat corresponds to the vibrissal area of MsI (Hall and Lindholm, '741, but here HRP positive cells bodies were situated mainly in layer V. HRP labeled cells bodies were also present in layer V of ipsilateral cortical area 29c. The ipsilateral nucleus ventralis thalami pars lateralis and the nucleus posterior thalami contained many HRP positive cell bodies and were associated with dense aggregations of developed silver grains. Numerous silver grains were also present over portions of the ipsilateral caudate, reticular nucleus of the thalamus and ventral pontine nuclei, but no HRP positive cell bodies occurred in these regions.HRP-filled axons left the injection site and traveled via the corpus callosum to contralateral PMBSF cortex where HRP labeled cell bodies were present mainly in layers I11 and V. Usually only one or two labeled somata were located superficial or deep to a contralateral PMBSF barrel. A few HRP positive cell bodies were also present in layers I1 and I11 of contralateral pyriform cortex.These results indicate that PMBSF cortex is reciprocally connected with ipsilateral cortical areas 6 and 40 and with the ipsilateral ventral and posterior nuclei of the thalamus. A small, homotopic callosal connection with contralateral PMBSF cortex has been demonstrated, and it is presumed that this projection is also reciprocal. PMBSF cortex projects to, but receives no projections from the ipsilateral caudate, reticular nucleus of the thalamus and the ventral pontine nuclei. Thus, many of the same projections of primary somatosensory cortex in higher animals, such as the monkey have been shown to occur in the mouse.Layer IV of primary somatosensory cortex in several species of rodent and in rabbit con-Woolsey, '75; Woolsey et al., '75b). In mice and rats the barrels in the posteromedial barrel tains multicellular units which have been 1 Support for this work provided by Boston University School of named (Woolsey and Van der Medicine General Research Support 1534-5 and National Science '70; Feldman and Pe...

AUF1 is a family of four proteins generated by alternative pre-mRNA splicing that form high affinity complexes with AU-rich, mRNA-destabilizing sequences located within the 3′ untranslated regions of many labile mRNAs. While AUF1 binding is most frequently associated with accelerated mRNA decay, emerging examples have demonstrated roles as a mRNA stabilizer or even translational regulator for specific transcripts. In this review, we summarize recent advances in our understanding of mRNA recognition by AUF1 and the biochemical and functional consequences of these interactions. In addition, unique properties of individual AUF1 isoforms and the roles of these proteins in modulating expression of genes associated with inflammatory, neoplastic, and cardiac diseases are discussed. Finally, we describe mechanisms that regulate AUF1 expression in cells, and current knowledge of regulatory switches that modulate the cellular levels and/or activities of AUF1 isoforms through distinct protein post-translational modifications. This article is part of a Special Issue entitled: RNA Decay mechanisms.

A recently developed Golgi-electron microscopic technique (Fairen et al., '77) has been used to identify neurons in mouse SmI cortex which are postsynaptic to degenerating thalamocortical axon terminals. It was found that thalamic axon terminals synapsed with dendrites of several distinct neuronal types whose cell bodies occurred either in layer 111, IV or V. The procedures employed were as follows: electrolytic lesions were used to destroy the cortical projections of the nucleus ventralis posterior pars lateralis thalami (homologous t o medial portion of ventrobasal complex) and the nucleus posterior thalami. These two thalamic nuclei project to the posteromedial barrel subfield (PMBSF) in mouse somatosensory cortex. Blocks of cortex containing the PMBSF were processed by the Golgi method, sectioned at 150 pm and examined with the light microscope. Neurons of interest were then selected for Golgi deimpregnation (Fairen et al., '77). Portions of these cells were serial thin sectioned and subsequently examined with the electron microscope to determine if they synapsed with degenerating axon terminals. Degenerating thalamocortical axon terminals synapsed a t asymmetrical synaptic junctions with dendritic spines of pyramidal cells whose somata occurred in layers I11 and V, and with dendritic spines of spiny stellate cells with somata in layer IV. Only normal, symmetrical synapses occurred on the cell bodies of these neurons, and no degenerating axon terminals synapsed with the shafts of their dendrites. Two, unimpregnated, non-spiny stellate cells whose somata occurred in layers IV and IV/V were partially reconstructed from serial thin sections. Many degenerating thalamocortical axon terminals synapsed with the dendrites and somata of these non-spiny cells. In fact, for similar lengths of dendrite, the non-spiny stellate cells made the most synapses with thalamocortical axon terminals, followed in order of decreasing frequency by the layer IV spiny stellate cells, the layer 111 pyramids and finally the layer V pyramids which received only few synapses from thalamocortical axon terminals.Direct evidence has been provided that at least six different types of neurons whose somata occur in several layers of the neocortex receive synapses from thalamocortically projecting neurons. It has been proposed that the cortex is organized such that thalamic input is processed sequentially by neurons of increasingly complex response properties beginning with cells in layer 1V and proceeding to cells in other layers (Hubel and Wiesel, '62, '68). The results of this study now suggest that any such hierarchical processing of thalamic input must occur in conjunction with the parallel, and perhaps simultaneous, processing of thalamic input by neurons at several hierarchical levels. The evidence for, and some implications of, a newly proposed model of cortical organization which combines hierarchical and parallel processing are discussed. It has been known for many years (e.g., Cajal, '1 1) that thalamocortical axons terminate p...