Octahedral Distortion and Displacement-Type Ferroelectricity with Switchable Photovoltaic Effect in a 3d

Because of the half-filled t_{2g}-electron configuration, the BO_{6} octahedral distortion in a 3d^{3} perovskite system is usually very limited. In this Letter, a perovskitelike oxide Hg_{0.75}Pb_{0.25}MnO_{3} (HPMO) with a 3d^{3} Mn^{4+} state was synthesized by using high pressure and high temperature methods. This compound exhibits an unusually large octahedral distortion enhanced by approximately 2 orders of magnitude compared with that observed in other 3d^{3} perovskite systems like RCr^{3+}O_{3} (R=rare earth). Essentially different from centrosymmetric HgMnO_{3} and PbMnO_{3}, the A-site doped HPMO presents a polar crystal structure with the space group Ama2 and a substantial spontaneous electric polarization (26.5 µC/cm^{2} in theory) arising from the off-center displacements of A- and B-site ions. More interestingly, a prominent net photocurrent and switchable photovoltaic effect with a sustainable photoresponse were observed in the current polycrystalline HPMO. This Letter provides an exceptional d^{3} material system which shows unusually large octahedral distortion and displacement-type ferroelectricity violating the "d^{0}-ness" rule.

Toward Clinically Applicable 3-Dimensional Tooth Segmentation via Deep Learning.

Digital dentistry plays a pivotal role in dental health care. A critical step in many digital dental systems is to accurately delineate individual teeth and the gingiva in the 3-dimension intraoral scanned mesh data. However, previous state-of-the-art methods are either time-consuming or error prone, hence hindering their clinical applicability. This article presents an accurate, efficient, and fully automated deep learning model trained on a data set of 4,000 intraoral scanned data annotated by experienced human experts. On a holdout data set of 200 scans, our model achieves a per-face accuracy, average-area accuracy, and area under the receiver operating characteristic curve of 96.94%, 98.26%, and 0.9991, respectively, significantly outperforming the state-of-the-art baselines. In addition, our model takes only about 24 s to generate segmentation outputs, as opposed to >5 min by the baseline and 15 min by human experts. A clinical performance test of 500 patients with malocclusion and/or abnormal teeth shows that 96.9% of the segmentations are satisfactory for clinical applications, 2.9% automatically trigger alarms for human improvement, and only 0.2% of them need rework. Our research demonstrates the potential for deep learning to improve the efficacy and efficiency of dental treatment and digital dentistry.

Recognition of alternating oligopurine/oligopyrimidine tracts of DNA by oligonucleotides with base-to-base linkages.

A new concept is presented to design and synthesize modified oligonucleotides in order to extend the range of double-helical DNA sequences that can be recognized by oligonucleotides via triple helix formation. The DNA target is composed of adjacent oligopurine.oligopyrimidine domains where the oligopurine sequences alternate on the two DNA strands. Canonical (C,T)-motif triple helices are formed with each oligopurine.oligopyrimidine domain of the target sequence. The two third-strand oligonucleotides were joined together via an appropriate linker between the two terminal bases with either a 3'-3' or a 5'-5' polarity. Molecular modeling was used to predict the optimal length of the linker bridging two terminal bases. The interaction of DNA with such a modified oligonucleotide containing a C3'-3'U linkage was studied by thermal dissociation, footprinting, and gel retardation experiments. They provide experimental evidence that the oligonucleotide does form a switched triple helix on this extended DNA target sequence. The binding of the so-called "switch oligonucleotide" is enhanced as compared to the two unlinked parental oligonucleotides which form triple helices with each oligopurine.oligopyrimidine domain of the target sequence.

[An epidemiologic study of workers with low back pain].

To evaluate the impact of low back pain we conducted a cross-sectional epidemiologic study of 10087 workers in factories of textile, machinery auto-transportation, clothing and sea cultivation. The prevalence of pain was compared with ages, sexes, duration of employment, types of jobs as well as body posture. The prevalence of low back in males was 13.66%, and in females 8.75% (average 11.53%). The risk factors included lifting, bending, twisting prolonged sitting and vibration as well as moisture and coldness prolonged sitting was. The important contributing factor of low back pain in sedentary workers.

[Preoperative management of scoliosis by positioning the trunk on its convex side].

A new method, hanging the scoliotic trunk on its convex side, for preoperative management of scoliosis was described and has been used on 36 patients with good result. The weight used varied individually from 10 kg to 40 kg to lift the convex side 5 to 8 cm above the bed surface on which he or she lay. Hanging in this way in about 2 weeks would stretch out and relax the soft tissues on the convex side, resulting in maximum correction. This method is simple, effective and without side effect. We would think that it is an ideal way for preoperative correction of idiopathic scoliosis.