Revealing the mechanism of DNA passing through graphene and boron nitride nanopores.

Nanopores on 2D materials have great potential for DNA sequencing, which is attributed to their high sequencing speed and reduced cost. However, identifying DNA bases at such a high speed with nanometer precision has remained a big challenge. Here, we implemented theoretical calculations to show the translocation of single-stranded DNA (ssDNA) through solid-state nanopores on a 2D hexagonal boron nitride (h-BN) and graphene sheet. A base-specific ssDNA sequencing technique was devised, based on the individual differences in the ion current responses for the (polyA)16, (polyG)16, (polyC)16, and (polyT)16 bases of ssDNA. Our sequential procedure for sequencing is built on a comparative approach between the current signals obtained from the nanopores to achieve base-specific detection. Our results indicate that at higher voltages (1.0, 1.2, 1.4, 1.6, 1.8 and 2.0 V nm-1), DNA translocation is tracked though the 1.5 and 2.0 nm nanopores, and at the 1.5 nm pore size, folded ssDNA close to the nanopore accounts for 93% and 81% of events for graphene and h-BN. Our calculations indicate charge transfer from the graphene to ssDNA, while the reverse happens in the case of the h-BN membrane. These results provide critical insights into our understanding of single molecule sequencing through solid-state nanopore research.

A Wearable Gait Phase Detection System Based on Force Myography Techniques.

(1) Background: Quantitative evaluation of gait parameters can provide useful information for constructing individuals’ gait profile, diagnosing gait abnormalities, and better planning of rehabilitation schemes to restore normal gait pattern. Objective determination of gait phases in a gait cycle is a key requirement in gait analysis applications; (2) Methods: In this study, the feasibility of using a force myography-based technique for a wearable gait phase detection system is explored. In this regard, a force myography band is developed and tested with nine participants walking on a treadmill. The collected force myography data are first examined sample-by-sample and classified into four phases using Linear Discriminant Analysis. The gait phase events are then detected from these classified samples using a set of supervisory rules; (3) Results: The results show that the force myography band can correctly detect more than 99.9% of gait phases with zero insertions and only four deletions over 12,965 gait phase segments. The average temporal error of gait phase detection is 55.2 ms, which translates into 2.1% error with respect to the corresponding labelled stride duration; (4) Conclusions: This proof-of-concept study demonstrates the feasibility of force myography techniques as viable solutions in developing wearable gait phase detection systems.

Effect of Thyroid Remnant Volume on the Risk of Hypothyroidism After Hemithyroidectomy: A Prospective Study.

BACKGROUND: Hypothyroidism is a common sequel after a hemithyroidectomy. Although various risk factors leading to hypothyroidism have been reported, the effect of the contralateral lobe's volume has been understudied. This study aimed to examine the association between the preoperative contralateral lobe's volume and the risk of postoperative hypothyroidism. METHODS: During a 2-year period, 150 eligible patients undergoing a hemithyroidectomy were evaluated. The volume of the contralateral nonexcised lobe was estimated preoperatively by independent assessors on ultrasonography using the following formula: width (in cm) × depth (in cm) × length (in cm) × (π/6), adjusted for the body surface area (BSA). Postoperative hypothyroidism was defined as serum thyroid-stimulating hormone (TSH) exceeding 4.78 mIU/L. Any significant characteristics in the univariate analysis were entered into the multivariate analysis to determine independent factors. RESULTS: After a mean follow-up period of 53.5 ± 9.4 months, 44 patients (29.3 %) experienced postoperative hypothyroidism, and 10 of these patients required thyroxine replacement. Hypothyroidism was associated with a higher preoperative TSH level (p < 0.001), a smaller BSA-adjusted volume (p < 0.001), fewer ipsilateral nodules (p = 0.037), and the presence of thyroiditis (p = 0.050). After adjustment for thyroiditis, preoperative TSH (p < 0.001), number of ipsilateral nodules (p = 0.048), and BSA-adjusted volume (p < 0.001) were independent factors for hypothyroidism. Patients with a BSA-adjusted volume smaller than 3.2 ml had a threefold greater hypothyroidism risk than those with a BSA-adjusted volume of 3.2 ml or more (p < 0.001). CONCLUSIONS: A significant inverse association between the preoperative contralateral lobe's volume and hypothyroidism risk was observed after hemithyroidectomy. Together with a higher preoperative TSH level and fewer ipsilateral nodules, a smaller BSA-adjusted volume measured by preoperative ultrasonography independently predicted hypothyroidism.

Wearable step counting using a force myography-based ankle strap.

INTRODUCTION: Step counting can be used to estimate the activity level of people in daily life; however, commercially available accelerometer-based step counters have shown inaccuracies in detection of low-speed walking steps (<2.2 km/h), and thus are not suitable for older adults who usually walk at low speeds. This proof-of-concept study explores the feasibility of using force myography recorded at the ankle to detect low-speed steps. METHODS: Eight young healthy participants walked on a treadmill at three speeds (1, 1.5, and 2.0 km/h) while their force myography signals were recorded at the ankle using a customized strap embedded with an array of eight force-sensing resistors. A K-nearest neighbour model was trained and tested with the recorded data. Additional three mainstream machine learning algorithms were also employed to evaluate the performance of force myography band as a pedometer. RESULTS: Results showed a low error rate of the step detection (<1.5%) at all three walking speeds. CONCLUSIONS: This study demonstrates not only the feasibility of the proposed approach but also the potential of the investigated technology to reliably monitor low-speed step counting.

Determination of reaction intermediate structures in heme proteins.

Developments in structural biology and molecular biology have allowed increasingly detailed investigations of structure-function relationships. Although atomic-resolution structures of proteins are becoming more common, a growing number of structural studies have focused on the role played by dynamics and have sought to determine the structure of intermediates in protein reactions. These experiments have revealed the first atomic-level pictures of enzyme catalysis and the conformational motions required for biological function. This chapter uses the cryotrapping of reaction intermediates in horse heart myoglobin (Mb) to illustrate the methods utilized in determining the structures of reaction intermediates in protein systems. The techniques described here are applicable to a wide variety of heme proteins including Mb, hemoglobin, photosynthetic reaction centers, and cytochrome p450cam.