Optical nanoimaging for block copolymer self-assembly.

One approach toward optical nanoimaging involves sequential molecular localization of photoswitchable fluorophores to achieve high resolution beyond optical limit of diffraction. Block copolymer micelles assembled from polystryrene-block-poly(ethylene oxide) block copolymers (PSt-b-PEO) are visualized in optical nanoimaging by staining the polystyrene blocks with spiropyrans (SPs). SPs localized in hydrophobic phase of block copolymer micelles exhibit reversible fluorescence on-off switching at alternating irradiation of UV and visible light. Phase-selective distribution of SPs in block copolymer micelles enables optical nanoimaging of microphase structures of block copolymer self-assembly at 50-nm resolution. To date, this is the sturdiest realization of optical nanoimaging with subdiffraction resolution for solution self-assembly of block copolymers.

Advanced Composites Inspired by Biological Structures and Functions in Nature: Architecture Design, Strengthening Mechanisms, and Mechanical-Functional Responses.

The natural design and coupling of biological structures are the root of realizing the high strength, toughness, and unique functional properties of biomaterials. Advanced architecture design is applied to many materials, including metal materials, inorganic nonmetallic materials, polymer materials, and so on. To improve the performance of advanced materials, the designed architecture can be enhanced by bionics of biological structure, optimization of structural parameters, and coupling of multiple types of structures. Herein, the progress of structural materials is reviewed, the strengthening mechanisms of different types of structures are highlighted, and the impact of architecture design on the performance of advanced materials is discussed. Architecture design can improve the properties of materials at the micro level, such as mechanical, electrical, and thermal conductivity. The synergistic effect of structure makes traditional materials move toward advanced functional materials, thus enriching the macroproperties of materials. Finally, the challenges and opportunities of structural innovation of advanced materials in improving material properties are discussed.

Scanning Accuracy of 10 Intraoral Scanners for Single-crown and Three-unit Fixed Denture Preparations: An In Vitro Study.

OBJECTIVE: To evaluate the accuracy of 10 intraoral scanners for single-crown and three-unit preparation models. METHODS: A maxillary partially edentulous model was fabricated. A dental cast scanner was used to obtain standard tessellation language (STL) data. Ten intraoral scanners, namely Trios 2 (TR2; 3Shape, Copenhagen, Denmark), True Definition (TD; 3M, Saint Paul, MN, USA), CEREC AC Omnicam (OM; Dentsply Sirona, Charlotte, NC, USA), Organical Scan Oral (OS; R+K, Berlin, Germany), PlanScan (PS; Planmeca, Helsinki, Finland), DWIOP (DW; Dental Wings, Montreal, Canada), Xianlin (XL; Hangzhou Xianlin, Hangzhou, China), DL-100 (DL; Guangzhou Longcheng, Guangzhou, China), Trios 3 (TR3; 3Shape) and i500 (MD; MEDIT, Seoul, South Korea) were used to obtain stereolithography data as test groups. Trueness, precision and surface accuracy were evaluated by deviation analysis using 3D image processing software. One tooth with a three-unit preparation for each test group was registered with the reference scan data, and the absolute distance from another tooth was calculated as the absolute accuracy. The data were analysed using a Mann-Whitney U test and Dunn-Bonferroni test (α = 0.05). RESULTS: The best trueness, precision and surface accuracy of scanning single crown preparation were recorded with TD (trueness 2.9 µm and precision 1.9 µm) and XL (surface accuracy 20.3 ± 2.9 µm). The best trueness, precision, surface accuracy and absolute accuracy of three-unit preparations were recorded with TD (2.6 µm), XL (1.9 µm), OM (27.1 ± 5.2 µm) and TR3 (79.2 ± 19.6 µm), respectively. There was no statistically significant difference in trueness between single- and multiple-unit preparations for any of the intraoral scanners (P > 0.05). A statistically significant difference in the surface accuracy between single and multiple preparations was found for TR2, TD, OM, DW, XL, DL and MD (P < 0.05). CONCLUSION: The trueness and precision of intraoral scanners for scanning three-unit preparations were nearly the same as those for single-crown preparations; however, with the exception of OS, PS and TR3, the surface accuracy of single-crown preparations was significantly better than that for three-unit preparations.

Soft magnetic skin for super-resolution tactile sensing with force self-decoupling.

Human skin can sense subtle changes of both normal and shear forces (i.e., self-decoupled) and perceive stimuli with finer resolution than the average spacing between mechanoreceptors (i.e., super-resolved). By contrast, existing tactile sensors for robotic applications are inferior, lacking accurate force decoupling and proper spatial resolution at the same time. Here, we present a soft tactile sensor with self-decoupling and super-resolution abilities by designing a sinusoidally magnetized flexible film (with the thickness ~0.5 millimeters), whose deformation can be detected by a Hall sensor according to the change of magnetic flux densities under external forces. The sensor can accurately measure the normal force and the shear force (demonstrated in one dimension) with a single unit and achieve a 60-fold super-resolved accuracy enhanced by deep learning. By mounting our sensor at the fingertip of a robotic gripper, we show that robots can accomplish challenging tasks such as stably grasping fragile objects under external disturbance and threading a needle via teleoperation. This research provides new insight into tactile sensor design and could be beneficial to various applications in robotics field, such as adaptive grasping, dexterous manipulation, and human-robot interaction.

The control of alginate degradation to dynamically manipulate scaffold composition for in situ transfection application.

In this study, nanofibrous scaffolds were used for in situ transfection application. Polyethylenimine (PEI)/DNA complexes adsorbed to alginate nanofibers, so the more alginate fibers resulted in the higher transfection efficiency. However, alginate was not favorable for cell adhesion. Therefore, poly (ε­caprolactone) (PCL) nanofibers were electrospun with alginate to improve biocompatibility. The in situ transfection results demonstrated that although the incorporated PCL fibers effectively improved cell morphology, the bioactivity and proliferation rates of surface cells were not significantly increased due to the high ratio of alginate fibers. However, the reduction of the alginate ratio may decrease transfection efficiency because the immobilization of nonviral vectors linearly depended on the density of alginate fibers. To maintain transfection efficiency and increase biocompatibility, the stability of alginate fibers were manipulated by adjusting the concentrations of calcium ions during crosslinking. These partially crosslinked alginate fibers were initially intact to allow nanoparticle adsorption for cell uptake, and then gradually degraded in days to create an appropriate environment for cell survival. This dynamic system successfully fulfilled the requirements of both gene delivery and biocompatibility. To our knowledge, this study may be the first one which dynamically regulates scaffold composition for substrate-mediated gene delivery.

Active changes of lignification-related enzymes in pepper response to Glomus intraradices and/or Phytophthora capsici.

The activities of enzymes responsible for lignification in pepper, pre-inoculation with arbuscular mycorrhizal (AM) fungus of Glomus intraradices and/or infection with pathogenic strain of Phytophthora capsici, and the biological control effect of G. intraradices on Phytophthora blight in pepper were investigated. The experiment was carried out with four treatments: (1) plants pre-inoculated with G. intraradices (Gi), (2) plants pre-inoculated with G. intraradices and then infected with P. capsici (Gi+Pc), (3) plants infected with P. capsici (Pc), and (4) plants without any of the two microorganisms (C). Mycorrhizal colonization rate was reduced by about 10% in pathogen challenged plants. Root mortality caused by infection of P. capsici was completely eliminated by pre-inoculation with antagonistic G. intraradices. On the ninth day after pathogen infection, Peroxidase (POD) activity increased by 116.9% in Pc-treated roots but by only 21.2% in Gi+Pc-treated roots, compared with the control, respectively. Polyphenol oxidase (PPO) and Phenylalanine ammonia-lyase (PAL) activities gradually increased during the first 3 d and dramatically decreased in Pc-treated roots but slightly decreased in Gi+Pc-treated roots, respectively. On the ninth day after pathogen infection, PPO and PAL decreased by 62.8% and 73.9% in Pc-treated roots but by only 19.8% and 19.5% in Gi+Pc-treated roots, compared with the control, respectively. Three major POD isozymes (45,000, 53,000 and 114,000) were present in Pc-treated roots, while two major bands (53,000 and 114,000) and one minor band (45,000) were present in spectra of Gi+Pc-treated roots, the 45,000 POD isozyme was significantly suppressed by G. intraradices, suggesting that the 45,000 POD isozyme was induced by the pathogen infection but not induced by the antagonistic G. intraradices. A 60,000 PPO isozyme was induced in Pc-treated roots but not induced in Gi+Pc-treated roots. All these results showed the inoculation of antagonistic G. intraradices alleviates root mortality, activates changes of lignification-related enzymes and induces some of the isozymes in pepper plants infected by P. capsici. The results suggested that G. intraradices is a potentially effective protection agent against P. capsici.

Evaluation of the Effect of the Closed-eruption Technique on Impacted Immature Maxillary Incisors.

OBJECTIVE: To investigate the effects of the closed-eruption technique on impacted immature maxillary incisors. METHODS: The contour and position of the gingival margin, root development, and pulp status were evaluated in 50 impacted immature maxillary incisors immediately after treatment and 2 years later. RESULTS: Chronic periapical periodontitis and trauma of the primary teeth were the main causes of impacted immature maxillary incisors. The average treatment time was 11 months. After treatment, the contour of the impacted incisor gingival margin, which had already erupted, conformed with the contralateral incisors; the gingival margin positions of 34 (68%) impacted incisors were the same as those of the contralateral incisors but the other 16 (32%) were more apical. All roots developed normally; pulp vitality was normal and conformed with the contralateral incisor change into a period. Three (6%) impacted incisors were slightly labially inclined because the dilacerated part of their roots was too long. CONCLUSION: The closed-eruption technique is an effective method of treating impacted immature maxillary incisors.

Multichannel wireless ECoG array ASIC devices.

Surgical resection of epileptogenic foci is often a beneficial treatment for patients suffering debilitating seizures arising from intractable epilepsy [1], [2], [3]. Electrodes placed subdurally on the surface of the brain in the form of an ECoG array is one of the multiple methods for localizing epileptogenic zones for the purpose of defining the region for surgical resection. Currently, transcutaneous wires from ECoG grids limit the duration of time that implanted grids can be used for diagnosis. A wireless ECoG recording and stimulation system may be a solution to extend the diagnostic period. To avoid the transcutaneous connections, a 64-channel wireless silicon recording/stimulating ASIC was developed as the electronic component of a wireless ECoG array that uses SIROF electrodes on a polyimide substrate[4]. Here we describe two new ASIC devices that have been developed and tested as part of the on-going wireless ECoG system design.

Li3V2(PO4)3@C core-shell nanocomposite as a superior cathode material for lithium-ion batteries.

Li3V2(PO4)3@C core-shell nanoparticles with typical sizes of 20-40 nm were synthesized using a hydrothermal-assisted sol-gel method. Ascorbic acid and PEG-400 were adopted as carbon sources and reductants. The uniform Li3V2(PO4)3@C nanocomposite obtained was composed of a Li3V2(PO4)3 core with high-phase purity and a graphitized carbon shell, which was characterized using XRD, SEM, TEM, and Raman analysis. The nanocomposite exhibited a remarkably high rate capability and long cyclability, delivering a discharge capacity of 138 mA h g(-1) at 5 C within a voltage range of 3-4.8 V and the capacity retention was 86% after 1000 cycles. The superior electrochemical performance of Li3V2(PO4)3@C indicates that it has potential for application as a cathode material in advanced rechargeable lithium-ion batteries.

Development and clinical application of a length-adjustable water phantom for total body irradiation.

A new type of water phantom which would be specialised for the absorbed dose measurement in total body irradiation (TBI) treatment is developed. Ten millimetres of thick Plexiglas plates were arranged to form a square cube with 300 mm of edge length. An appropriate sleeve-type piston was installed on the side wall, and a tabular Plexiglas piston was positioned inside the sleeve. By pushing and pulling the piston, the length of the self-made water phantom could be varied to meet the required patients' physical sizes. To compare the international standard water phantom with the length-adjustable and the Plexiglas phantoms, absorbed dose for 6-MV X ray was measured by an ionisation chamber at different depths in three kinds of phantoms. In 70 cases with TBI, midplane doses were metered using the length-adjustable and the Plexiglas phantoms for simulating human dimensions, and dose validation was synchronously carried out. There were no significant statistical differences, p > 0.05, through statistical processing of data from the international standard water phantom and the self-designed one. There were significant statistical differences, p < 0.05, between the two sets of data from the standard and the Plexiglas one. In addition, the absolute difference had a positive correlation with the varied depth of the detector in the Plexiglas phantom. Comparing the data of clinical treatment, the differences were all <1 % among the prescription doses and the validation data collected from the self-design water phantom. However, the differences collected from the Plexiglas phantom were increasing gradually from +0.77 to +2.30 % along with increasing body width. Obviously, the difference had a positive correlation with the body width. The results proved that the new length-adjustable water phantom is more accurate for simulating human dimensions than Plexiglas phantom.