Optical Trapping of a Single Molecule of Length Sub-1 nm in Solution

Plasmonic optical manipulation has emerged as an affordable alternative to manipulate single chemical and biological molecules in nanoscience.Although the theoretical models of sub-5 nm single-molecule trapping have been considered promising,the experimental strategies remain a challenge due to the Brownian motions and weak optical gradient forces with significantly reduced molecular polarizability.Herein,we address direct trapping and in situ sensing of single molecules with unprecedented size,down to∼5Åin solution,by employing an adjustable plasmonic optical nanogap and single-molecule conductance measurement.The theoretical simulations demonstrate that local fields with a high enhancement factor,over 103,were generated at such small nanogaps,resulting in optical forces as large as several piconewtons to suppress the Brownian motion and trap a molecule of length sub-1 nm.This work demonstrates a strategy for directly manipulating the small molecule units,promising a vast multitude of applications in chemical,biological,and materials sciences at the single-molecule level.

Clinical Characteristics and Treatment of Spontaneous Osteonecrosis of Medial Tibial Plateau： A Retrospective Case Study

Background： In a small proportion of cases, spontaneous osteonecrosis of the knee （SONK） involves the medial tibial plateau （MT）. Here, we introduced the clinical characteristics of spontaneous osteonecrosis of the MT and unicompartmental knee arthroplasty （UKA） as the favorable treatment for this situation based on a retrospective case study. Methods： Patients with spontaneous osteonecrosis of the MT, confirmed by magnetic resonance imaging （MRI） at Guangdong Provincial Hospital of Chinese Medicine （China） from March 2015 to June 2016, were included as a case serial and analyzed retrospectively. All patients underwent Oxford Medial UKA. The characteristics of their lesions, corresponding treatment, and results of follow-up were presented. The lesion scores and grade were determined according to the criteria of Ficat and Arlet. Results： In total, 22 patients （5 men, 17 women： mean age, 64.1 years） with spontaneous osteonecrosis of the MT were analyzed. The lesion stages assessment showed that 3 （14%） were Stage 11, 10 （45%） were Stage Ⅲ, 7 （32%） were Stage IV, and 2 （9%） were Stage V. In the sagittal plane, 7 （32%） were in the anterior region （MTa） and 15 （68%） were central （MTc）. The lesion volume averaged 2.24 ± 0.79 cm3 （range： 1.57-3.08 cm3）. Seventeen patients （77%） had Level Ⅲ posterior medial meniscus root tears （MM RTs）. All the patients underwent UKA. Average follow-up was 30.0 ± 6.4 months with a range of 23.0-38.0 months. The visual analog scale score was 7.78 ± 0.67 belbre surgery while decreased to 2.22 ± 1.09 at the final follow-up （P 〈 0.001 ）. The Hospital for Special Surgery scores of pre-/post-surgery were 65.67 ± 5.45 and 84.10 ± 4.20, respectively （P 〈 0.001 ）. Conclusions： SONK often occurs in the anterior and central tibial plateau due to abnormal stresses. Most of the patients had Level Ⅲ posterior medial meniscus root tears. MRI is recommended for suspected cases to identity SONK at an early stage. The use of the Oxford Medial UKA for SONK of the MT is reliable both immediately and at follow-up.

Universality of slip avalanches in a ductile Fe-based bulk metallic glass

Intermittent serrated flows of a novel ductile Fe60Ni20P13C7 bulk metallic glass（BMG）at variant strain rates were investigated by statistics analysis.Peak and clutter distribution of slip-avalanche magnitudes are displayed during stable plastic flows at strain rates of 2×10-4 s-1 and 5×10-5 s-1,respectively,which means that serration behavior depends on the strain rate.However,the remarkable agreement between measured slip-avalanche magnitudes and the scaling behavior,i.e.a universal complementary cumulative distribution function（CCDF）predicted by mean-field theory（MFT）model,indicates that the plasticity of the present Fe-based BMGs can be tuned by imposed strain rates：Smax^6）ε-λ.This tuned plasticity is elucidated with expended free-volume model.Moreover,the scaling behavior of serrated flows for other strain rates can be predicted as well.