Pulsed 808-nm infrared laser stimulation of the auditory nerve in guinea pig cochlea

Pulsed near-infrared radiation has been proposed as an alternative stimulus for auditory nerve stimulation and could be potentially used in the design of cochlear implant. Although the infrared with high absorption coefficient of water (i.e., wavelength ranged from 1.8 to 2.2 μm) has been widely investigated, the lymph in the cochlea absorbs most of the infrared energies, and only a small part can arrive at the target auditory nerves. The present study is aimed to test whether the short-wavelength near-infrared irradiation with lower absorption coefficients can penetrate the lymph fluid to stimulate the auditory nerves. An 808-nm near-infrared laser was chosen to stimulate the auditory nerve in the guinea pig cochlea. The infrared pulse was delivered by an optical fiber that was surgically inserted near the round window membrane and oriented toward the spiral ganglion cells in the basal turn of the cochlea. The 2-Hz infrared pulses were used to stimulate the cochlea before and after the deafness with different pulse durations (100–1,000 μs). Optically evoked compound action potentials (oCAPs) were recorded during the infrared radiation. We successfully recorded oCAPs from both normal hearing animals and deafened animals. The oCAP amplitude increased with the infrared radiation energy. The preliminary experiment suggests that the near-infrared with lower absorption coefficients can effectively pass through the lymph filled in the cochlea and stimulate the auditory nerve. Further studies will optimize the deafness animal model and determine the optimal stimulation parameters.     

超声弹性成像诊断肝纤维化的研究进展

慢性肝病会引起肝纤维化,最终导致肝硬化,从而引起出血、肝衰竭、肝性脑病等致死性的并发症。早期肝纤维化可逆,发展到肝硬化则难以逆转。作为一种诊断肝纤维化的新技术,超声弹性成像技术因其快捷、准确、无创、可重复性强等特点而成为近年研究热点。本文就超声弹性成像在诊断肝纤维化中的应用进行综述。     

高强聚焦超声消融兔腹主动脉旁肝肿瘤对腹主动脉的影响

目的观察高强聚焦超声(HIFU)消融兔腹主动脉旁肝肿瘤对腹主动脉的影响。方法对43只实验兔建立腹主动脉旁VX2肝肿瘤模型,于MR引导下行HIFU消融肿瘤,通过彩色多普勒超声观察消融前、消融后即刻、2h和6h腹主动脉充盈情况,测量血流峰值血流速(PSV)、平均血流速度(Vm)、平均血流量、阻力指数(RI)和搏动指数(PI)变化;病理观察消融前及消融后即刻腹主动脉的改变情况。结果共对40只实验兔成功建立腹主动脉旁肝肿瘤模型。消融后即刻腹主动脉血流通畅,未见明显狭窄、塌陷或闭塞。较之消融前,消融后即刻腹主动脉PSV、Vm和平均血流量明显减慢,RI和PI明显上升(P均0.05),之后逐渐恢复,于消融后6h恢复至消融前水平(P均0.05)。病理学检查示消融后即刻腹主动脉无损伤。结论 HIFU消融腹主动脉旁肿瘤可一过性改变腹主动脉血流动力学,而对管壁无明显损伤。     

磁共振引导下经颅聚焦超声治疗的研究进展

MR引导下聚焦超声是一种新兴的无创治疗技术。由于颅骨的遮挡以及缺乏有效的影像引导,聚焦超声在颅内的应用一度受到很大的限制。近年来,随着MRI以及超声相控阵技术的发展,聚焦超声在治疗颅内肿瘤及非肿瘤疾病、开放血脑屏障等方面逐渐显示出巨大潜力。本文就MR引导下经颅聚焦超声的发展现状及应用前景进行综述。     

A novel gastroretentive porous microparticle for anti-Helicobacter pylori therapy: Preparation, in vitro and in vivo evaluation

Gastroretentive drug delivery system is a promising option for the treatment of Helicobacter pylori infection, which can prolong gastric residence time and supply high drug concentration in the stomach. In the present study, a low density system of metronidazole-loaded porous Eudragit^® RS microparticle with high drug loading capacity (>25%) was fabricated via electrospray method. The porous structure and size distribution of microparticles were affected by polymer concentration and flow rate of solution. FTIR and XRD analyses indicated that drug has been entrapped into the porous microparticles. In addition, sustained release profiles and slight cytotoxicity in vitro were detected. Gamma scintigraphy study in vivo demonstrated that ¹³¹I-labeled microparticles retained in stomach for over 8 h, and about 65.50% radioactive counts were finally detected in the region of interest. The biodistribution study confirmed that hotspot of radioactivity was remaining in the stomach. Furthermore, metronidazole-loaded porous microparticles can eradicate H. pylori completely with lower dose and administration frequency of antibiotic compared with pure drug, which were also more helpful for the healing of mucosal damages. These results suggest that prepared porous microparticle has the potential to provide better treatment for H. pylori infection.     

Structural Analysis of Composite Conical Convex-Concave Plate (CCCP) Using VAM-Based Equivalent Model

Compared with the ordinary foundation plate, the composite conical convex-concave plate (CCCP) has obvious anisotropic characteristics, and there is less research on the relationship between its mechanical properties and structural parameters. In this article, a numerical model for the equivalent stiffness of a typical unit cell with conical convex is established by using the variational asymptotic method. Then, the 3D finite element model (3D-FEM) of CCCP is transformed into 2D equivalent plate model (2D-EPM) with the effective plate properties obtained from the constitutive analysis of unit cell. The accuracy of 2D-EPM is verified by comparing with the displacement, natural frequencies, and buckling results from 3D-FEM under different boundary conditions. Then, the influence of geometric parameters and layup configurations on the effective performances of CCCP are investigated. Finally, the buckling loads and natural frequencies of bidirectional CCCP are compared with those of CCCP by using the present model. The present model is particularly useful in the early design stage of CCCP where many design trade-offs need to be made over a vast design space in terms of material selection, ply angles, and geometric parameters.     

Investigation on cure kinetics of epoxy resin containing carbon nanotubes modified with hyper-branched polyester

The cure kinetics of epoxy resin cured by diethyltoluene diamine (D-EP), D-EP/multi-walled carbon nanotube (D-EP/CNT) composites and D-EP/hyper branched polyester functionalized CNTs (D-EP/CNTs-H20) were investigated by non-isothermal differential scanning calorimetry (DSC). Results revealed that the presence of CNTs shifted the cure temperature to a lower temperature and accelerated the curing of D-EP, and the addition of CNTs-H20 exhibited a stronger effect in accelerating the cure of D-EP. Activation energies were calculated based on the Kissinger approach and Ozawa approach respectively. Lowered activation energy was observed after the addition of CNTs or CNTs-H20 at low degrees of cure, indicating that the CNTs had a large effect on the curing reaction. The presence of CNTs facilitated the curing reaction, especially the initial epoxyamine reaction. Moreover, CNTs-H20 exhibited better performance. The autocatalytic model was used to describe the cure kinetics phenomena of the studied systems. When CNTs or CNTs-H20 were added, the Sesták–Berggren model still can describe the cure kinetics of the D-EP composites because the results, calculated by the model, agreed with the experimental data well. Moreover, the kinetics parameters as well as the equation describing the cure process were proposed.

The cure kinetics of epoxy resin cured by D-EP, D-EP/CNT composites and D-EP/CNTs-H20 were investigated by non-isothermal differential scanning calorimetry (DSC).     

Room temperature two-photon-pumped random lasers in FAPbBr3/polyethylene oxide (PEO) composite perovskite thin film

Solution-processed organic–inorganic halide lead perovskites have attracted increasing attention due to their great potential in low-cost, effective, and versatile light emission applications and large-scale portable optoelectronic devices. In this paper, formamidinium lead tribromide perovskite thin films composited with polyethylene oxide (PEO) were fabricated by a solution processing method. Great enhancement of photoluminescence was observed and more attractively, two-photon-pumped random lasing action could be achieved at room temperature when pumped by a nanosecond pulse laser with excitation wavelength centered at 1064 nm. Evident transition from spontaneous upconversion emission to random lasing action was investigated by monitoring the log–log light emission slope and peak width at half height. The lasing threshold is at around 1.1 mJ cm⁻², which is comparable to that of other two-photon upconversion random lasers. The efficient random lasing emission originates from the multiple random scattering provided by the micrometer-scale rugged morphology and polycrystalline grain boundaries. Compared with conventional lasers that normally serve as a coherent light source, the perovskite random lasers show promise in fabricating low-cost thin-film lasing devices for flexible and speckle-free imaging applications.

Solution-processed organic–inorganic halide lead perovskites have attracted increasing attention due to their great potential in low-cost, effective, and versatile light emission applications and large-scale portable optoelectronic devices.     

Health effects in the Flemish population in relation to low levels of mercury exposure: From organ to transcriptome level

Due to possible health risks, quantification of mercury accumulation in humans was included in the Flemish biomonitoring programmes FLEHS I (2002–2006) and FLEHS II (2007–2011). The general objective of FLEHS I was to assess regional exposure levels in order to link possible differences in these internal exposure levels to different types of local environmental pressure. Therefore, Hg and MMHg (methylmercury) were only measured in pooled blood samples per region and per age class. In FLEHS II, mercury concentrations were measured in hair of each participant. About 200 adolescents and 250 mothers (reference group) and two times 200 adolescents (2 hotspots) were screened. The main objectives of the FLEHS II study were: (1) to determine reference levels of mercury in hair for Flanders; (2) to assess relations between mercury exposure and possible sources like fish consumption; (3) to assess dose–effect relations between mercury exposure and health effect markers. The results showed that mercury concentrations in the Flemish population were rather low compared to other studies. Mercury levels in the Flemish populations were strongly related to the age of the participants and consumption of fish. Significant negative associations were observed between mercury in hair and asthma, having received breast feeding as a newborn, age at menarche in girls, allergy for animals and free testosterone levels. Significant correlations were also observed between mercury in hair and genes JAK2, ARID4A, Hist1HA4L (boys) and HLAdrb5, PIAS2, MANN1B1, GIT and ABCA1 (girls).     

Beyond direct impact: Evidence synthesis towards a better understanding of effectiveness of environmental health interventions

Systematic reviews are a cornerstone of evidence-based public health, and there is much discussion on how this method may need to be modified to do justice to complex interventions, such as environmental health interventions. This paper asserts that intervention effectiveness is influenced by variability in five distinct layers – direct (intrinsic) impact, user compliance, delivery, programming and policy measures – which are embedded in the broader geographical, socio-economic, political and cultural context. The multi-component, multi-sectoral nature of most environmental health interventions results in a complex relationship between these layers of influence, involving systemic interactions. As illustrated with examples, understanding environmental health interventions critically relies on considering all of these layers. These distinct layers of influence can serve as a framework towards the comprehensive analysis of environmental health interventions in systematic reviews, drawing on quantitative and qualitative methods and a variety of disciplines.