Lipid-based nanocarrier for quercetin delivery: system characterization and molecular interactions studies

The flavonoid quercetin (QU) is a naturally occurring compound with several biological activities. However, the oral bioavailability of this compound is very low due to the high pre-systemic metabolism in the colon and liver and its low water solubility. In this context, the development of QU-loaded nanocarriers (NEs) is a promising approach to improve the drug oral bioavailability. This study investigates the variation of the concentration of 12-hydroxystearic acid–polyethylene glycol copolymer, lecithin and castor oil (CO) as to increase the amount of QU encapsulated while maintaining physicochemical characteristics described in previous studies. To better understand the ability to load and release the drug, we investigated the molecular interactions between QU and NE. Lipid-based NEs were prepared using CO as oily phase and PEG 660-stearate and lecithin as surfactants. Hot solvent diffusion and phase inversion temperature were methods employed to produce NEs. The QU-NEs were investigated for physicochemical characteristics and in vitro drug release. Molecular interactions between QU and the NEs were monitored through the complementary infrared (Fourier transform infrared) and NMR. The results revealed that it was possible to incorporate higher amounts of QU in a lipid-based NE with a reduced size (20?nm). The system developed allow a sustained release of QU probably due to the shell formed by the surfactants around the NE and the flavonoid ordering effect in the emulsion hydrophobic regions, which may reduce the system permeability.     

Economic feasibility of bifacial silicon solar cells

Bifacial solar cells and modules are a promising approach to increase the energy output of photovoltaic systems, and therefore decrease levelized cost of electricity (LCOE). This work discusses the bifacial silicon solar cell concepts PERT (passivated emitter, rear totally diffused) and BOSCO (both sides collecting and contacted) in terms of expected module cost and LCOE based on in‐depth numerical device simulation and advanced cost modelling. As references, Al‐BSF (aluminium back‐surface field) and PERC (passivated emitter and rear) cells with local rear‐side contacts are considered. In order to exploit their bifacial potential, PERT structures (representing cells with single‐sided emitter) are shown to require bulk diffusion lengths of more than three times the cell thickness. For the BOSCO concept (representing cells with double‐sided emitter), diffusion lengths of half the cell thickness are sufficient to leverage its bifacial potential. In terms of nominal LCOE, BOSCO cells are shown to be cost‐competitive under monofacial operation compared with an 18% efficient (≙ p_MPP = 18 mW/cm²) multicrystalline silicon (mc‐Si) Al‐BSF cell and a 19% mc‐Si PERC cell for maximum output power densities of p_MPP ≥ 17.3 mW/cm² and p_MPP ≥ 18.1 mW/cm², respectively. These values assume the use of $10/kg silicon feedstock for the BOSCO and $20/kg for the Al‐BSF and PERC cells. For the PERT cell, corresponding values are p_MPP ≥ 21.7 mW/cm² and p_MPP ≥ 22.7 mW/cm², respectively, assuming the current price offset (≈50%, at the time of October 2014) of n‐type Czochralski‐grown silicon (Cz‐Si) compared with mc‐Si wafers. The material price offset of n‐type to p‐type Cz‐Si wafers (≈15%, October 2014) currently accounts for approximately 1 mW/cm², which correlates to a conversion efficiency difference of 1%_abs for monofacial illumination with 1 sun. From p‐type mc‐Si to p‐type Cz‐Si (≈30% wafer price offset, October 2014), this offset is approximately 2.5 mW/cm² for a PERT cell. When utilizing bifacial operation, these required maximum output power densities can be transformed into required minimum rear‐side illumination intensities for arbitrary front‐side efficiencies η_front by means of the performed numerical simulations. For a BOSCO cell with η_front = 18%, minimum rear‐side illumination intensities of ≤ 0.02 suns are required to match a 19% PERC cell in terms of nominal LCOE. For an n‐type Cz‐Si PERT cell with η_front = 21%, corresponding values are ≤ 0.11 suns with 0.05 suns being the n‐type to p‐type material price offset. This work strongly motivates the use of bifacial concepts to generate lowest LCOE. Copyright © 2016 John Wiley & Sons, Ltd.     

Retinal ganglion cell layer and visual function in a patient with optic disc drusen

BACKGROUND: To correlate the retinal ganglion cell pattern to visual acuity and visual field data in a patient with bilateral optic disc drusen, a quantitative clinicopathological study was carried out. METHODS: Both retinae of a patient with optic drusen were whole-mounted. Retinal ganglion cell counts were made using a sampling scheme covering the whole retina and compared to the findings in 10 normal retinae. Relative ganglion cell reduction in the drusen retinae was correlated to clinical data. RESULTS: The total retinal ganglion cell count was reduced from 1244858+/-98736 in normal retinae to 305319 on the right and 527571 on the left eye with optic disc drusen. Large ganglion cells had a better chance of survival. Parafoveal ganglion cell loss was 57% for the right and 36% for the left eye, while visual acuity was 0.8 and 1.0 respectively. The mean light sensitivity loss increased from the centre (6.2 dB) to paracentral (9.9 dB), mid-peripheral (13.7 dB) and outer peripheral (15.0 dB) retina, while ganglion cell losses were smallest in outer peripheral retina (21.9%), followed by central (53.0%), mid-peripheral (70.9%) and paracentral retina (87.7%). CONCLUSION: These data validate Frisén's theory on central retinal resolution and provide the structural basis for the clinical rule that low visual acuity should not be attributed to disc drusen. Automated light sense perimetry gives an inadequate picture of retinal damage caused by optic disc drusen.     

Interactive Modeling and Authoring of Climbing Plants

We present a novel system for the interactive modeling of developmental climbing plants with an emphasis on efficient control and plausible physics response. A plant is represented by a set of connected anisotropic particles that respond to the surrounding environment and to their inner state. Each particle stores biological and physical attributes that drive growth and plant adaptation to the environment such as light sensitivity, wind interaction, and physical obstacles. This representation allows for the efficient modeling of external effects that can be induced at any time without prior analysis of the plant structure. In our framework we exploit this representation to provide powerful editing capabilities that allow to edit a plant with respect to its structure and its environment while maintaining a biologically plausible appearance. Moreover, we couple plants with Lagrangian fluid dynamics and model advanced effects, such as the breaking and bending of branches. The user can thus interactively drag and prune branches or seed new plants in dynamically changing environments. Our system runs in real‐time and supports up to 20 plant instances with 25k branches in parallel. The effectiveness of our approach is demonstrated through a number of interactive experiments, including modeling and animation of different species of climbing plants on complex support structures.     

分区无处可藏找回硬盘中的GPT隐藏空间

最近笔者入手了一块250GB的二手硬盘,打算把它当作移动硬盘使用。将其接入电脑后,在Windows XP的磁盘管理中,可看到其分区结构。笔者打算将所有分区全部删除,却发现最前端的“GPT保护分区”无论如何都删不掉,也无法格式化。虽然其容量仅为200MB,但把它留着实在不算完美,而且也不明白GPT保护分区有什么作用,是否会对移动硬盘的使用构成影响。于是笔者就在网上进行了一番调查。