The dynamics of water molecules in a single-walled carbon nanotube (SWNT) under continuous deformations was studied with molecular dynamics simulations. The flux and occupancy remain almost fixed within a deformation of 2.0 A but decrease sharply for a further deformation of 0.6 A. The nanopore is an excellent on-off gate that is both effectively resistant to deformation noises and sensitive to available signals. Biological water channels are expected to share this advantage due to similar wavelike water distributions. The minimal external force required for triggering an open-close transition falls within the working range of many available experimental facilities, which provides the possibility of developing SWNT-based nanoscale devices.

We have implemented a secure network file system called SUNDR that guarantees the integrity of data even when malicious parties control the server. SUNDR splits storage functionality between two untrusted components, a block store and a consistency server. The block store holds all file data and most metadata. Without interpreting metadata, it presents a simple interface for clients to store variable-sized data blocks and later retrieve them by cryptographic hash.The consistency server implements a novel protocol that guarantees close-to-open consistency whenever users see each other's updates. The protocol roughly consists of users exchanging version-stamped digital signatures of block server metadata, though a number of subtleties arise in efficiently supporting concurrent clients and groupwritable files. We have proven the protocol's security under basic cryptographic assumptions. Without somehow producing signed messages valid under a user's (or the superuser's) public key, an attacker cannot tamper with a user's files-even given control of the servers and network. Despite this guarantee, SUNDR performs within a reasonable factor of existing insecure network file systems.

The tooth root is an integral, functionally important part of our dentition. The formation of a functional root depends on epithelialmesenchymal interactions and integration of the root with the jaw bone, blood supply and nerve innervations. The root development process therefore offers an attractive model for investigating organogenesis. Understanding how roots develop and how they can be bioengineered is also of great interest in the field of regenerative medicine. Here, we discuss recent advances in understanding the cellular and molecular mechanisms underlying tooth root formation. We review the function of cellular structure and components such as Hertwig's epithelial root sheath, cranial neural crest cells and stem cells residing in developing and adult teeth. We also highlight how complex signaling networks together with multiple transcription factors mediate tissue-tissue interactions that guide root development. Finally, we discuss the possible role of stem cells in establishing the crown-to-root transition, and provide an overview of root malformations and diseases in humans.

ReasoningReasoning ReasoningFigure 1: The overview of our proposed inpainting scheme. The masked image is first mapped into the convolutional feature space and processed by a shared Feature Reasoning module recurrently. After the feature map is fully recovered, the generated feature maps are merged together (Omitted in this figure) and the merged feature is translated back to a RGB image.

Understanding and controlling the transport of water across nanochannels is of great importance for designing novel molecular devices, machines and sensors and has wide applications, including the desalination of seawater. Nanopumps driven by electric or magnetic fields can transport ions and magnetic quanta, but water is charge-neutral and has no magnetic moment. On the basis of molecular dynamics simulations, we propose a design for a molecular water pump. The design uses a combination of charges positioned adjacent to a nanopore and is inspired by the structure of channels in the cellular membrane that conduct water in and out of the cell (aquaporins). The remarkable pumping ability is attributed to the charge dipole-induced ordering of water confined in the nanochannels, where water can be easily driven by external fields in a concerted fashion. These findings may provide possibilities for developing water transport devices that function without osmotic pressure or a hydrostatic pressure gradient.

Background Intralipid, a brand name for the first safe fat emulsion for human use, has been shown to be cardioprotective. However, the mechanism of this protection is not known. Here we investigated the molecular mechanism(s) of Intralipid-induced cardioprotection against ischemia/reperfusion injury, particularly the role of GSK-3β and mitochondiral permeability transition pore in this protective action. Methods In-vivo rat hearts or isolated Langendorff-perfused mouse hearts were subjected to ischemia followed by reperfusion with Intralipid (1% in ex-vivo and one bolus of 20% in in-vivo) or vehicle. The hemodynamic function, infarct size, threshold for the opening of mitochondiral permeability transition pore and phosphorylation levels of Akt/ERK/GSK-3β were measured. Results Administration of Intralipid at the onset of reperfusion resulted in ~70% reduction in infarct size in the in-vivo rat model. Intralipid also significantly improved functional recovery of isolated Langendorff-perfused mouse hearts as the rate pressure product was increased from 2999±863mmHg*beats/min in control to 13676±611 mmHg*beats/min (Mean±SEM) and the infarct size was markedly smaller (18.3±2.4% vs. 54.8±2.9% in control, P<0.01). The Intralipid-induced cardioprotection was fully abolished by LY294002, a specific inhibitor of PI3K, but only partially by PD98059, a specific ERK inhibitor. Intralipid also increased the phosphorylation levels of Akt/ERK1/GSK-3β by 8, 3 and 9 fold, respectively. The opening of mitochondiral permeability transition pore was inhibited by Intralipid as calcium retention capacity was higher in Intralipid group (274.3±8.4nM/mg vs. 168.6±9.6nM/mg control). Conclusions Postischemic treatment with Intralipid inhibits the opening of mitochondiral permeability transition pore and protects the heart through GSK-3β via PI3K/Akt/ERK pathways.

An important issue in nanopore sensing is to construct stable and versatile sensors that can discriminate analytes with minute differences. Here we report a means of creating nanopores that comprise ultrashort single-walled carbon nanotubes inserted into a lipid bilayer. We investigate the ion transport and DNA translocation through single-walled carbon nanotube nanopores and find that our results are fundamentally different from previous studies using much longer single-walled carbon nanotubes. Furthermore, we utilize the new single-walled carbon nanotube nanopores to selectively detect modified 5-hydroxymethylcytosine in single-stranded DNA, which may have implications in screening specific genomic DNA sequences. This new nanopore platform can be integrated with many unique properties of carbon nanotubes and might be useful in molecular sensing such as DNA-damage detection, nanopore DNA sequencing and other nanopore-based applications.

Sirtuins [sirtuin (SIRT)1-SIRT7] mediate the longevity-promoting effects of calorie restriction in yeast, worms, flies, and mice. Additionally, SIRT3 is the only SIRT analog whose increased expression has been shown to be associated with longevity in humans. The polyphenol resveratrol (RSV) is the first compound discovered able to mimic calorie restriction by stimulating SIRTs. In the present study, we report that RSV activated SIRT3 in cardiac fibroblasts both in vivo and in vitro. Moreover, in wild-type mice, RSV prevented cardiac hypertrophy in response to hypertrophic stimuli. However, this protective effect was not observed in SIRT3 knockout mice. Additionally, the activation of SIRT3 by RSV ameliorated collagen deposition and improved cardiac function. In isolated cardiac fibroblasts, pretreatment with RSV suppressed fibroblast-to-myoblast transformation by inhibiting the transforming growth factor-β/Smad3 pathway. Therefore, these data indicate that the activation of SIRT3 by RSV could ameliorate cardiac fibrosis and improve cardiac function via the transforming growth factor-β/Smad3 pathway.