Prevalence, genetic and clinical characteristics in first-degree relatives of patients with familial cerebral cavernous malformations in China.

OBJECTIVE: This study aims to investigate the prevalence of familial cerebral cavernous malformations (FCCMs) in first-degree relatives (FDRs) using familial screening, to describe the distribution of initial symptoms, lesion count on cranial MRI and pathogenic gene in patients. METHODS: Patients with multiple CCMs who enrolled from the Treatments and Outcomes of Untreated Cerebral Cavernous Malformations in China database were considered as probands and FDRs were recruited. Cranial MRI was performed to screen the CCMs lesions, and whole-exome sequencing was performed to identify CCM mutations. MRI and genetic screening were combined to diagnose FCCM in FDRs, and the results were presented as prevalence and 95% CIs. The Kaplan-Meier (KM) method was used to calculate the cumulative incidence of FCCM. RESULTS: 33 (76.74%) of the 43 families (110 FDRs) were identified as FCCM (85 FDRs). Receiver operating characteristic analysis revealed three lesions on T2-weighted imaging (T2WI) were the strong indicator for distinguishing probands with FCCM (sensitivity, 87.10%; specificity, 87.50%). Of the 85 FDRs, 31 were diagnosed with FCCM, resulting in a prevalence of 36.5% (26.2%-46.7%). In families with FCCMs, the mutation rates for CCM1, CCM2 and CCM3 were 45.45%, 21.21% and 9.09%, respectively. Furthermore, 53.13% of patients were asymptomatic, 17.19% were intracranial haemorrhage and 9.38% were epilepsy. The mean age of symptom onset analysed by KM was 46.67 (40.56-52.78) years. CONCLUSION: Based on MRI and genetic analysis, the prevalence of CCMs in the FDRs of families with FCCMs in China was 36.5%. Genetic counselling and MRI screening are recommended for FDRs in patients with more than three CCM lesions on T2WI.

Investigations on dynamics of interacting cavitation bubbles in strong acoustic fields.

Given its importance to the dynamics of cavitation bubbles, the mutual interaction between bubbles was carefully investigated in this work. The cavitation noises emitted in different sonication conditions were recorded to study the dynamical behavior of the bubbles. The frequency spectra of the noises suggest that the dispersing state of the bubbles severely influence the oscillations of bubbles, and that the nonlinear feature of the dynamics of cavitation bubbles, imposed by the mutual bubble-bubble interaction, gradually develops with the decrease of the dispersing height. Theoretical analysis shows that the size difference between the interacting bubbles should be responsible for the increase of nonlinearity of the oscillation, and that the decrease of the distance between them could effectively enhance the nonlinear feature of the oscillation of the bubble, both of which agree well with the experimental observation.

Approach and Coalescence of Gold Nanoparticles Driven by Surface Thermodynamic Fluctuations and Atomic Interaction Forces.

The approach and coalescence behavior of gold nanoparticles on a silicon surface were investigated by experiments and molecular dynamics simulations. By analyzing the behavior of the atoms in the nanoparticles in the simulations, it was found that the atoms in a single isolated nanoparticle randomly fluctuated and that the surface atoms showed greater fluctuation. The fluctuation increased as the temperature increased. When there were two or more neighboring nanoparticles, the fluctuating surface atoms of the nanoparticles "flowed" toward the neighboring nanoparticle because of atomic interaction forces between the nanoparticles. With the surface atoms "flowing", the gold nanoparticles approached and finally coalesced. The simulation results were in good agreement with the experimental results. It can be concluded that surface thermodynamic fluctuations and atomic interaction forces are the causes of the approach and coalescence behavior of the gold nanoparticles.

Spontaneous transition of a water droplet from the Wenzel state to the Cassie state: a molecular dynamics simulation study.

It is widely accepted that the superhydrophobic state is attributed to the formation of the Cassie state. The Cassie state is mostly metastable, which can be turned into the Wenzel state. Therefore, the superhydrophobic state is generally considered to be unstable. In this study, the wetting behaviors of a water droplet on different pillar surfaces are simulated. The spontaneous transition from the Wenzel state to the Cassie state is achieved, which is significant for the stable existence of superhydrophobicity. The transition process is analyzed in detail and can be chronologically divided into two stages: the contact area decreases and the water droplet rises. Moreover, the transition mechanism is studied, which is due to the combined effect of the surrounding pillars and the central pillar. The surrounding pillars form a no-wetting gap under the droplet, and the central pillar forces the droplet to move upward. Furthermore, three parameters that may influence the transition are studied: the pillar height, the droplet size and the hollow size.

Molecular dynamics simulations of wetting behavior of water droplets on polytetrafluorethylene surfaces.

Molecular dynamics simulations are performed to simulate the wetting behavior of nanosized water droplets on flat and pillar polytetrafluorethylene surfaces. The results show that the cutoff of the Lennard-Jones (LJ) potential has a large effect on the simulated value of the contact angle and some suggestions are given on how to choose an appropriate cutoff. On flat surfaces, the contact angle is independent of the size of the water droplet, which was determined by the energy parameters of the LJ potential. Furthermore, on pillar surfaces, two different equilibrium states are present: wetted contact and cross contact. For the wetted contact state, the contact angle increases with increasing droplet size and pillar size within a certain range. However, for the cross contact state, the contact angle and droplet size are uncorrelated, which results from the layering and structuring of molecules after their penetration into the hollows between pillars. However, additional simulations show that the final state depends on the initial geometry and the cross contact state is a metastable wetting state.

Self-assembly of polytetrafluoroethylene nanoparticle films using repulsive electrostatic interactions.

An approach for manufacturing polytetrafluoroethylene nanoparticle films using repulsive electrostatic interactions was developed. This approach used the strong repulsive force between colloidal nanoparticles and a substrate surface to cause the colloidal nanoparticles to suspend and self-assemble at a near-wall equilibrium position. A suspended monolayer was formed and was subsequently deposited on the substrate surface. A relatively large-area (3 × 3 cm(2)), close-packed unordered monolayer of polytetrafluoroethylene nanoparticles was observed. Multilayer nanoparticle films were also generated by increasing the particle concentration and deposition time. This work confirms the feasibility of nanoparticle self-assembly under repulsive electrostatic interactions and provides new routes for the large-area fabrication of monolayer and multilayer close-packed nanoparticle films.

Underwater locomotion strategy by a benthic pennate diatom Navicula sp.

The mechanism of diatom locomotion has been widely researched but still remains a hypothesis. There are several questionable points on the prevailing model proposed by Edgar, and some of the observed phenomena cannot be completely explained by this model. In this paper, we undertook detailed investigations of cell structures, locomotion, secreted mucilage, and bending deformation for a benthic pennate diatom Navicula species. According to these broad evidences, an updated locomotion model is proposed. For Navicula sp., locomotion is realized via two or more pseudopods or stalks protruded out of the frustules. The adhesion can be produced due to the pull-off of one pseudopod or stalk from the substratum through extracellular polymeric substances. And the positive pressure is generated to balance the adhesion because of the push-down of another pseudopod or stalk onto the substratum. Because of the positive pressure, friction is generated, acting as a driving force of locomotion, and the other pseudopod or stalk can detach from the substratum, resulting in the locomotion. Furthermore, this model is validated by the force evaluation and can better explain observed phenomena. This updated model would provide a novel aspect on underwater locomotion strategy, hence can be useful in terms of artificial underwater locomotion devices.

Settlement and cell division of diatom Navicula can be influenced by light of various qualities and intensities.

Diatom settlement and cell division is important in two major aspects. Firstly, biofouling is a costly problem in the shipping industry that necessitates the effective inhibition of diatom settlement and proliferation. Secondly, biological coatings on the basis of ordered and densely packed cell lawns of diatom are useful for nano- and biotechnology. This study demonstrated that the settlement and cell division of the marine unicellular diatom Navicula sp. can be influenced by light-emitting diodes of various light qualities and intensities. Except for blue light, the settlement of diatoms was reduced by weak (approx. 0.14-6 µE m(-2) s(-1)) green, yellow or red light. When the irradiance intensity, however, was higher than 8-9 µE m(-2) s(-1), the settlement was stimulated. This phenomenon could be explained by the hypothesis of spatial interference between a chloroplast and a holdfast-like structure. Densely packed lawn of diatoms with uniform distribution can be fabricated for nanotechnologies, using blue light that stimulates diatom cell division.

Frequency spectrum of the noise emitted by two interacting cavitation bubbles in strong acoustic fields.

The dynamics and acoustic emission of two interacting cavitation bubbles exposed to strong acoustic fields with a frequency of 515 KHz are investigated numerically in this paper. After comparing the dynamics of a single bubble excited by the given pressure waves, bubbles with ambient radii of 2 and 5 µm were chosen to be studied to discuss the influence of the mutual bubble-bubble interaction on the dynamic behaviors and acoustic emission of the bubbles. The results show that, aside from the external driving pressure waves, the interaction between the bubbles imposes an extra nonlinear effect on the oscillations of the bubbles and that the dynamics of the smaller bubble could be suppressed gradually with the enhancement of this mutual interaction by decreasing the distance between the bubbles. Moreover, the improvement in the oscillation nonlinearity of the bubbles due to the change in the ambient circumstance could readily be observed from the frequency spectra of the bubbles' acoustic emission, which interprets the change by exhibiting an appropriate development of the subharmonics, the ultraharmonics, and the broadband component.

Influence of illumination on settlement of diatom Navicula sp.

Diatoms are responsible for biofouling, which causes many problems in various marine industries. This study examined the effects of different light conditions (intensity, incident direction, time of illumination) on the settling behavior of the marine diatom Navicula sp. on glass surfaces. The density of this diatom's settlement on glass was strongly influenced by light conditions. Moreover, very weak light emitted on the bottom of the culture dish could also rapidly inhibit diatom settlement. These phenomena were explained by spatial interference between chloroplast and holdfast-like structures inside the thecae. The holdfast-like structure is observed to be responsible for diatom locomotion and hence the settlement behavior. It was proposed that the interrelation of illumination and attachment of diatoms allowed them to better adapt to the habitat with higher efficiency of attachment and successive reproduction.

Field emission property of hydrogenated chemical vapor deposited diamond films studied by scanning tunneling microscopy.

By using scanning tunneling microscopy, the plots of tunneling current versus applied voltage, at the local points for hydrogenated and oxygenated chemical vapor deposited diamond films, were investigated. For comparison, the measurement points were adopted on the centers of the crystalline grains and at the grain boundaries, respectively. The results indicated that, for the hydrogenated chemical vapor deposited diamond, the field emission character is much better on the center of the crystalline grains than at the grain boundary. In contrast, for the oxygenated samples, the crystalline grains show a poor field emission character. The two diamond surfaces exhibit similar field emission characters at the grain boundaries. The surface emission mechanisms of the hydrogenated chemical vapor deposited diamond films were also discussed.

Ab initio study of hydrogen-boron interactions in diamond films.

Based on density functional theory, the equilibrium geometries and densities of states corresponding to several diamond models with different hydrogen-boron complexes have been investigated. The results indicated that when the density of hydrogen atom is comparable to that of boron, the diamond surface exhibits no shallow acceptors as a result of a passivation of boron by hydrogen atom. When the density of hydrogen atom is two times higher than that of boron, the diamond surface converts to a n-type conductivity induced by a B-2Hbc complex. The results in this work confirm the previous experimental findings.

First principles study of water monomer adsorption on charged Fe(110) surface.

In order to clarify the binding site and orientation of H2O monomer on Fe(110) surfaces with different charges, the potential dependent adsorption of water monomer over charged Fe(110) surface has been studied using first principles method. The results indicate that H2O molecular prefers to special orientation on the surface with different charges. In addition, the internal structure of H2O molecule deforms deeply due to different adsorption effect. The adsorption process is an exothermic and endothermic process for the surface with positive and negative charges, respectively. The covalence function is the dominant interaction in this adsorption system.

Criteria for entrapped gas under a drop on an ultrahydrophobic surface.

Ultrahydrophobicity of a rough surface is mainly attributed to the entrapped gas under a drop. Two criteria were proposed for the entrapped gas: an intruding angle criterion and an intruding depth criterion. These two criteria are that the intruding angle must be less than the maximum asperity slope angle and the intruding depth must be less than the height of the asperities. The intruding angle is determined by the true contact angle, the surface geometry, and the drop size. The intruding angle is directly proportional to the true contact angle, and it increases with an increase of the fractional area of the liquid-gas interface under the drop and with a decrease of the linear dimension of the three-phase contact line on the asperities. The effect of the drop size on the intruding angle is induced by Laplace and hydrostatic pressures. The intruding depth increases with an increase of the intruding angle and the distance between the asperities. The proposed criteria were evaluated using experiment data from the literature. Comparison between the experiment and calculation results showed that the experiment data supported the theory.