Group 14 metallole dianions as η5^5-coordinating ligands

As heavier aromatic analogs of the cyclopentadienides, group 14 dianionic metalloles exhibit more versatile reactivity and coordination modes due to the additional lone pair at the heteroatom. Compared to the well-established chemistry of monoanionic cyclopentadienide ligands, the coordination chemistry with those dianionic ligands remains underexplored. This perspective provides an overview of literature-known examples of group 14 metallole dianions (silole, germole, stannole and plumbole) adopting η$^5$-coordinating modes. The diverse coordination modes and reactivity exhibited by these compounds highlight their potential as intriguing ligands in organometallic chemistry

Constrained CycleGAN for Effective Generation of Ultrasound Sector Images of Improved Spatial Resolution

Objective. A phased or a curvilinear array produces ultrasound (US) images with a sector field of view (FOV), which inherently exhibits spatially-varying image resolution with inferior quality in the far zone and towards the two sides azimuthally. Sector US images with improved spatial resolutions are favorable for accurate quantitative analysis of large and dynamic organs, such as the heart. Therefore, this study aims to translate US images with spatially-varying resolution to ones with less spatially-varying resolution. CycleGAN has been a prominent choice for unpaired medical image translation; however, it neither guarantees structural consistency nor preserves backscattering patterns between input and generated images for unpaired US images. Approach. To circumvent this limitation, we propose a constrained CycleGAN (CCycleGAN), which directly performs US image generation with unpaired images acquired by different ultrasound array probes. In addition to conventional adversarial and cycle-consistency losses of CycleGAN, CCycleGAN introduces an identical loss and a correlation coefficient loss based on intrinsic US backscattered signal properties to constrain structural consistency and backscattering patterns, respectively. Instead of post-processed B-mode images, CCycleGAN uses envelope data directly obtained from beamformed radio-frequency signals without any other non-linear postprocessing. Main Results. In vitro phantom results demonstrate that CCycleGAN successfully generates images with improved spatial resolution as well as higher peak signal-to-noise ratio (PSNR) and structural similarity (SSIM) compared with benchmarks. Significance. CCycleGAN-generated US images of the in vivo human beating heart further facilitate higher quality heart wall motion estimation than benchmarks-generated ones, particularly in deep regions

Forging a Cage into a Chain: Stepwise Transformation of P4_4 by Silylenes to a Si3_3P4_4 Motif

We have discovered a route to access the longest low-valent molecular silaphospha-chain, a seven-membered chain structure that incorporates three silicon and four phosphorus atoms by stepwise activation of white phosphorus (P$_4$) using two different silylene precursors. The chain species was formed via a highly reactive polyphosphide intermediate. The isolation of a stable analogue of this reaction intermediate was achieved by stepwise reaction with mono and bis(silylenes). Due to the rigidity of the ferrocenediyl framework of the bis(silylene), the isomerization process of the chain structure was hampered. Theoretical studies such as natural bond orbital and atoms in molecules analyses of the seven-membered chain species indicated some degree of delocalization of the double bond system

Structure of the substrate-engaged SecA-SecY protein translocation machine.

The Sec61/SecY channel allows the translocation of many proteins across the eukaryotic endoplasmic reticulum membrane or the prokaryotic plasma membrane. In bacteria, most secretory proteins are transported post-translationally through the SecY channel by the SecA ATPase. How a polypeptide is moved through the SecA-SecY complex is poorly understood, as structural information is lacking. Here, we report an electron cryo-microscopy (cryo-EM) structure of a translocating SecA-SecY complex in a lipid environment. The translocating polypeptide chain can be traced through both SecA and SecY. In the captured transition state of ATP hydrolysis, SecAs two-helix finger is close to the polypeptide, while SecAs clamp interacts with the polypeptide in a sequence-independent manner by inducing a short β-strand. Taking into account previous biochemical and biophysical data, our structure is consistent with a model in which the two-helix finger and clamp cooperate during the ATPase cycle to move a polypeptide through the channel

(R)-N-(Biphenyl-4-yl)-tert-butane­sulfinamide

In the title compound, C16H19NOS, the dihedral angle between the two aromatic rings is 38.98 (8)°. The crystal structure is stabilized by N—H⋯O hydrogen bonds, which link neighbouring mol­ecules into chains running parallel to the a axis