Entangled Nanoparticles: Discovery by Visualization in 4D Electron Microscopy

Particle interactions are fundamental to our understanding of nanomaterials and biological assemblies. Here, we report on the visualization of entangled particles, separated by as large as 70 nm, and the discovery of channels in their near-fields. For silver nanoparticles, the induced field of each particle extends to 50-100 nm, but when particles are brought close in separation we observe channels as narrow as 6 nm, a width that is 2 orders of magnitude smaller than the incident field wavelength. The channels' directions can be controlled by the polarization of the incident field, particle size, and separation. For this direct visualization of these nanoscopic near-fields, the high spatial, temporal, and energy resolutions needed were hitherto not possible without the methodology given here. This methodology, we anticipate, paves the way for further fundamental studies of particle entanglement and for possible applications spanning materials and macromolecular assemblies.     

Barriers to completion of healthcare proxy forms: a qualitative analysis of ethnic differences

To determine whether history of chronic lung disease (CLD) in children born at very low birthweight (VLBW) confers additional risk for impaired health, growth, and neurodevelopment, 17 VLBW children born in 1984 who had CLD (requiring supplemental oxygen more than 30 days after birth) in infancy and 28 VLBW children who did not have CLD were assessed at age 7 years. Assessments included a medical history, standard physical and neurological examinations, pulmonary-function tests, and tests of neuropsychological and psychoeducational functioning. Health status did not differ between the groups. In contrast, children with CLD did not perform as well in neuropsychological and psychoeducational assessments. Although CLD confers little added risk to health, it seems to add significantly to risks for poor school performance that are known to be associated with very low birthweight.     

Stromal development in the ventral prostate, anterior prostate and seminal vesicle of the rat

The prostate and seminal vesicle (SV) are androgen-dependent secretory glands of the male genital tract. They produce the bulk of the seminal secretions. The object of the present study was to examine and document the ontogeny of stromal maturation in the rat anterior and ventral prostate and SV. These organs have a loosely organized cellular mesenchyme during fetal development. During prostatic development the mesenchyme condensed to form smooth muscle sheaths immediately surrounding the epithelium, with looser connective tissue between individual ducts. In the SV, a loose connective tissue layer called the lamina propria lies between the epithelium and developing muscle. Smooth muscle alpha-actin, myosin, desmin, laminin, vinculin, vimentin and androgen receptor (AR) expression were examined by immunocytochemical methods during the pre- and postnatal developmental periods. The first marker to be detected was vimentin, which was initially found throughout the mesenchyme. During development vimentin became mostly restricted to the interductal tissue of the prostate and the lamina propria of the SV. Smooth muscle markers were expressed in an orderly sequence in a proximal to distal manner along prostatic ducts, from the urethra towards the tips. Expression of alpha-actin was followed by vinculin, myosin, desmin, and laminin. These markers became localized to the developing smooth muscle sheaths and were not expressed in the interductal tissue of the prostate or the lamina propria of the SV. Organ culture experiments demonstrated that androgens were required for the differentiation of smooth muscle sheaths. Castration of adult rats demonstrated that androgens were required to maintain smooth muscle differentiation. In castrates, the stroma was relatively thicker but less dense than in intact animals. Following castration, expression of the smooth muscle markers was lost sequentially in the reverse order of their expression during development. In long-term castrates alpha-actin, vimentin and a small amount of vinculin were detected. AR were first detected in the urogenital sinus mesenchyme immediately surrounding the epithelium at 16 days of gestation. As development progressed expression of AR became more widespread, and postnatally was found throughout the mesenchyme. As maturation of smooth muscle occurred, stromal expression of AR became localized to the muscular sheath immediately surrounding the epithelium. In the prostate the interductal connective tissue displayed very low levels of AR expression. In the SV, AR were also observed in the lamina propria. In summary, stromal differentiation and dedifferentiation in the rat prostate and SV were found to be androgen-dependent processes with ordered sequential ontogenic expression of specific markers.     

An improved approach to delivery of enteral nutrition in the intensive care unit

Using immunohistochemistry, vasoactive intestinal peptide (VIP) was visualized in taste bud cells of the carp, Cyprinus carpio, and the European catfish, Silurus glanis, by means of light and electron microscopy. Intracellular membrane systems, presumably smooth endoplasmic reticulum, of light (sensory) cells, but not of dark (supporting) cells and basal cells, were densely labelled with antibody. In the frog (four species: Rana temporaria, R. ridibunda, R. arvalis, R. pipiens), taste bud cells did not label. However, the dense basal nerve fibre plexus, some subepithelial ganglionic cells, but no ascending intragemmal fibres, were immunoreactive. In fish, the results support evidence that VIP is involved in the modulation of taste transduction at the level of receptor cells. In the frog, an indirect, possibly vasodilatatory effect on taste perception may be considered.     

Electrohydrodynamic phenomena on the explosive-emissionliquid-metal cathode

The paper describes the results of a direct experimental observation of the development of an electrohydrodynamic instability at an explosive-emission liquid-metal cathode along with a theoretical analysis of the growth and destruction of the protrusion formed on the cathode surface     

Forming Single-Phase Laminates via the Gelcasting Technique

Single–phase laminates of iron titanate were formed by gelcasting in both the presence and absence of a magnetic field to produce alternating layers of textured and nontextured microstructure, respectively. X–ray analysis was performed on each lamina verifying that alignment was maintained throughout processing. Tunnel cracks were found in trilayer laminates (nontextured/textured/nontextured) when the alignment direction was parallel to the interface between layers. The cracks are consistent with a stress profile of residual tension parallel to the interface in the textured layer.     

Ceramic Laminates by Gelcasting

Laminated ceramic composites are appealing for many applications due to their unique and customizable thermal and mechanical properties. Gelcasting is a relatively new, yet commercially proven, near-net-shape processing technique suitable for laminate production. A review of gelcasting techniques and a discussion of their application to laminate processing are provided, along with an overview of laminate design and processing concerns. Specific examples of single-phase laminates produced via gelcasting are provided, including porous/dense alumina and magnetically aligned iron titanate and barium hexaferrite structures.     

Evolution of an ensemble of mesoscopic defects during deformation of a heterogeneous material with a regular structure

Using the methods of location and temporal amplitude analysis of the acoustic emission signals accompanying the deformation of a heterogeneous material with a regular structure, it has been established that the region of macroscopic breakage of a sample is by no means uniquely related to mesocracks accumulated in the preceding stages. Moreover, the region of fracture exhibits no clear and correlated hierarchy of the nucleating and growing mesocracks. The main crack appears in a quite random manner as a result of the alternating active formation of mesocracks in various local regions and the progressing decrease in dissipative capacity of the surrounding volume under the action of an applied load.