The prevention of diabetic retinopathy requires drugs that leverage the benefits of glycemic control without adding the burden of side effects. Aspirin at dosages of 1–1.5 g/day has prevented manifestations of diabetic retinal microangiopathy in a clinical trial as well as in studies with dogs. Because lower and safer doses of aspirin could be used if its beneficial effects on retinopathy were due to antithrombotic effects, we compared the effects of a selective antiplatelet drug (clopidogrel) to those of aspirin in streptozotocin-induced diabetic rats. Clopidogrel did not prevent neuronal apoptosis, glial reactivity, capillary cell apoptosis, or acellular capillaries in the retina of diabetic rats. Aspirin, at doses yielding serum levels (<0.6 mmol/l) well below the anti-inflammatory range for humans, prevented apoptosis of capillary cells and the development of acellular capillaries but did not prevent neuroglial abnormalities. The aldose reductase inhibitor sorbinil, used as the benchmark for the effect of the other drugs, prevented all abnormalities. The diabetic rat retina showed increased expression of the transcription factor CCAAT/enhancer-binding protein-β, one of the known targets of low-intermediate concentrations of aspirin. Thus we found a spectrum of drug efficacy on the prevention of experimental diabetic retinopathy, ranging from the absent effect of a selective antiplatelet drug to the prevention of all abnormalities by an aldose reductase inhibitor. Aspirin at low-intermediate concentrations selectively prevented microangiopathy. The minimal effective dose of aspirin should now be sought.
Background/aims: To demonstrate how spectral domain optical coherence tomography (SDOCT) can better evaluate drusen and associated anatomical changes in eyes with non-neovascular age-related macular degeneration (AMD) compared with time domain optical coherence tomography (TDOCT). Methods: Images were obtained from three eyes of three patients with AMD using an experimental SDOCT system. Both a titanium–sapphire (Ti:sapphire) laser and a superluminescent diode (SLD) were used as a broadband light source to achieve cross-sectional images of the retina. A qualitative and quantitative analysis was performed for structural changes associated with non-neovascular AMD. An automated algorithm was developed to analyse drusen area and volume from SDOCT images. TDOCT was performed using the fast macular scan (StratusOCT, Carl Zeiss Meditec, Dublin, California). Results: SDOCT images can demonstrate structural changes associated with non-neovascular AMD. A new SDOCT algorithm can determine drusen area, drusen volume and proportion of drusen. Conclusions: With new algorithms to determine drusen area and volume and its unprecedented simultaneous ultra-high speed ultra-high resolution imaging, SDOCT can improve the evaluation of structural abnormalities in non-neovascular AMD.
Precise fabrication of semiconducting channel materials into densely-aligned uniform arrays is one prerequisite towards the high-performance ultra-scaled technology nodes, in particular for carbon nanotubes (CNTs). Traditional thin-film approaches generally yield CNTs in irregularly-spaced bundles or with wide orientation distribution, and lack a mechanism to effectively eliminate the mis-aligned CNTs from the ultra-scaled channel area. Therefore, the averaged pitch value and precision of CNT arrays, the key parameters defining lateral CNT spacing, fail to simultaneously meet all of the patterning requirements for the ultra-scaled technology nodes. Bio-fabrication is promising for patterning CNTls at a resolution beyond the existing lithographic limit. However, impacted by surface charges and sub-micron dimensions of typical bio-templates, current bio-templated electronics exhibit both poor transport performance and array uniformity smaller than 1 micron. We report precise scaling of inter-CNT pitch using a supramolecular assembly method called Spatially Hindered Integration of Nanowire Electronics (SHINE). Specifically, by using nano-trenches to align CNTs and DNA hybridization to stabilize them in place, we constructed parallel CNT arrays with uniform pitch as small as 10.4 nm, at an assembly yield over 95%. The pitch precision improves on that prepared from conventional thin-film approaches by more than two orders of magnitude. Compared to the lithography-patterned Si channels at 10 nm technology node, SHINE simultaneously provides both 70% smaller averaged pitch value and molecular-scale pitch precision in the channel area. By engineering the interfacial compositions, metal ions and surface charges that are destructive to FET performance have been excluded from the channel area without degrading CNT alignment. Under a source-to-drain voltage of -0.5 V, we demonstrate both transconductance more than 0.6 mS/μm with fast on/off switching. And the key FET performance metrics are improved by more than one order of magnitude than previous bio-templated FETs. Furthermore, we demonstrate centimeter-scale alignment of fixed-width CNT arrays. At the interface of high-performance electronics and bio-molecular self-assembly, precise bio-fabrication could provide ultra-scaled devices or circuits compatible with or sensitive to local biological environments.
Complex plasmas consist of low-temperature plasmas with embedded
microparticles. The microparticles acquire electric charges of thousands
of electrons and strongly interact with each other. Due to their relatively large size and slow speed, their movement can be recorded
with digital cameras and traced from frame to frame. Here, we study
the propagation of waves across an interface formed between two subclouds of microparticles of different sizes. For this, we use data recorded under microgravity using the PK-3 Plus Laboratory on board the International Space Station, as well as Langevin dynamics simulations of
a complex plasma. Firstly, we study how self-excited waves are transmitted across the interface and demonstrate that a collision zone and
a merger zone form. Secondly, we study the propagation of a solitary
wave across an interface and demonstrate that at low pressures, reflection at the interface can be observed.
Recent advances in structural DNA nanotechnology, including DNA origami and DNA bricks, have enabled arbitrarily complexed nanopatterns. However, most of these DNA structures are limited with sub-100 nm dimensions because of the limits from the length of scaffold strand, as well as the sequence library. This review will focus on different strategies for scaling-up DNA self-assembly, including the hierarchical assembly of the preformed DNA building blocks both in solution and on surface, the scaffolded assembly of finite sized DNA structures, the nonhierarchical assembly of single-stranded DNA bricks, and the seed-mediated algorithmic assembly. The design criteria, the building blocks, and the key assembly conditions for each assembly strategy are described. In addition, the future challenges, as well as application potentials of large-area DNA structures, are discussed.
We report here experimental data for transmission of electromagnetic waves through a variety of softmaterial structures made of plastic tubes and ionic solutions, as compared to that in the free space. The results firmly support the theory on softmaterial waveguides in the environment of ionic solutions. This is a solid step towards a better understanding of the underlying physics for the electrical communication in biosystems through axons and membranes. It also offers valuable insight for further experiments with artificial materials at the nanoscale, and experiments in live animals.
Literature values for the gas-phase basicity (GB) and proton affinity (PA) of glutamic acid range from 216 to 224 kcal/mol (GB) and 218 to 241 kcal/mol (PA). In this paper, a high-level theoretical study aimed at resolving the apparent disagreement among the experimental values is presented. Hartree−Fock, MP2, and DFT calculations with large basis sets were carried out on the neutral and protonated forms of glutamic acid. Nine protonated and 21 neutral conformers were located at the HF/3-21G and B3LYP/6-31+G** levels with full geometry optimization and characterization of stationary points. The energetics were subsequently reevaluated at the MP2(full)/6-311+G(2d,p)//B3LYP/6-31+G** level. Thermodynamic data in the harmonic approximation were obtained at the B3LYP/6-31+G** level. This data was used to estimate the gas-phase distribution of conformers at 298 K. The lowest energy structures of protonated and neutral glutamic acid both exhibit cyclic structures due to the formation of intramolecular hydrogen bonds. The calculated PA and GB are 224.4 and 214.4 kcal/mol, respectively. It is shown that, when certain empirical corrections for the entropy of cyclization are omitted and appropriate adjustments are made to thermodynamic scales, the GB and gas-phase PA values reported here are in excellent agreement with a variety of previous experimental measurements.
Self-assembly of trimesic acid (TMA) displayed remarkable abundance over its full coverage range on gold under ultrahigh vacuum conditions. Experiments showed that previously well-reported "chicken wire" and "flower" structures were actually two special cases within its full coverage. All observed assembling structures formed hexagonal porous networks that could be well-described by a unified model in which the TMA molecules inside the half unit cells (equilateral triangles) were bound via trimeric hydrogen bonds and all half unit cells were connected to each other via dimeric hydrogen bonds. These porous networks possessed pores of 1.1 ± 0.1 nm in diameter, and the interpore distance was tunable from 1.6 nm on at a step size of ∼0.93 nm. Energetics analysis unveiled that the assembling structures less than one molecular layer was optimally driven by maximization of the dimeric hydrogen bonds.
Abstract Background To assess the safety and efficacy of phakic refractive lens (PRL) implantation for correcting high myopia, as well as an ophthalmic viscosurgical device-free (OVD-free) method for PRL implantation. Methods In this real-world prospective study, consecutive patients implanted with PRL in one or both eyes were enrolled. Based on the surgical techniques used, the eyes were divided into the OVD-free method group and the conventional method group. The patients were examined 2 h after surgery and were scheduled for follow-up at 1 day, 1 week, 1 month, 3 months, 6 months, and 12 months. The corrected distance visual acuity (CDVA), uncorrected distance visual acuity (UDVA), the manifest refraction spherical equivalent (MRSE), intraocular pressure (IOP) and lens vault were assessed postoperatively. Corneal endothelial cell density (ECD) was measured at the 3- and 12-month postoperative visits. Results Fifty-seven consecutive patients (108 eyes) were enrolled. At the 3-month postoperative visit, both mean UDVA and CDVA were significantly improved after PRL implantation (0.19 ± 0.21 and 0.01 ± 0.14 logMAR) with efficacy index and safety index of 0.92 and 1.30, respectively. None of the eyes had any loss of CDVA. The percentage of eyes within ± 0.50 D and ± 1.00 D of target refraction was 58% and 83%, respectively. Mean MRSE changed from − 14.49 ± 4.22 D, preoperatively, to − 1.22 ± 1.26 D at 1 day ( P < 0.001) and remained stable thereafter. Mean endothelial cell loss was 11.3%, 9.6%, respectively, at 3 and 12 months, with no significant difference between the two follow-ups ( P = 0.395). Fifty-nine eyes received the OVD-free method, and 49 eyes received the conventional method. The OVD-free method demonstrated a significant reduction in the incidence of early acute IOP elevations (28.8% vs. 53.1%, P = 0.022) compared to the conventional method. The difference of initial endothelial cell loss (9.4 ± 14.2% vs. 13.6 ± 14.6%) between the two groups trended toward significance ( P = 0.056). In both groups, no other major complications were observed up to 12-month follow-up. Conclusions PRL implantation was a safe, efficient, predictable and stable method for correcting high myopia. The potential of lower incidence of early acute IOP elevations makes the OVD-free method a promising alternative to the conventional method. Trail registration : Chinese Clinical Trial Registry, ChiCTR2100043600. Registered on 23 February 2021, https://www.chictr.org.cn/showproj.html?proj=122229
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