Disorder and suppression of quantum confinement effects in Pd nanoparticles

Size-selectable ligand-passivated crystalline and amorphous Pd nanoparticles (<4 nm) are synthesized by a novel two-phase process and verified by high-resolution transmission electron microscopy. Scanning tunneling spectroscopy preformed at 5 K on these two types of nanoparticles exhibits clear Coulomb blockade and Coulomb staircases. Size dependent multipeak spectral features in the differential conductance curve are observed for the crystalline Pd particles but not for the amorphous particles. Theoretical analysis shows that these spectral features are related to the quantized electronic states in the crystalline Pd particle. The suppression of the quantum confinement effect in the amorphous particle arises from the reduction of the degeneracy of the eigenstates and the level broadening due to the reduced lifetime of the electronic states.

Substitution of a non-retinal phospholipase C in Drosophila phototransduction

The Drosophila norpA gene encodes at least two subtypes of phospholipase C (PLC), one of which is essential for phototransduction and the other is utilized in signalling pathways other than phototransduction. The two subtypes of norpA-PLC differ by 14 amino acids that have been proposed as important for the function of PLC in different signalling pathways. The present study aimed to determine whether norpA subtype II enzyme can functionally substitute for the subtype I enzyme in the phototransduction pathway. We found that the non-retinal norpA-PLC enzyme can substitute for its retinal counterpart, but that there is a reduced rate of repolarization of photoreceptors following intense light stimuli. This reduced repolarization might be due to the inability of a regulatory component being able to interact with the non-retinal norpA-PLC enzyme.

Low-temperature orientationally ordered structures of two-dimensional C60

Orientationally ordered structures of two-dimensional (2D) C(60) at low temperature have been investigated theoretically and experimentally. Using total energy optimization with a phenomenological potential, we find the ground state is a close packed hexagonal lattice in which all the molecules have the same orientation. Several local minima of the potential energy surface are found to be associated with other 1 x 1 lattices as well as 2 x 2 lattices. The energies of the orientational domain boundaries of the 1x1 lattices are also computed, and two kinds of which yield negative values. A majority of these theoretical findings are confirmed by our low-temperature scanning tunneling microscopy study of a 2D C(60) array supported on a self-assembled monolayer.

Imaging subsurface reflection phase with quantized electrons

Lead quantum wells (QW) epitaxially grown on annealed Pb/Si(111) interface form a model system for the study of interactions between quantized electrons and adiabatically modulated boundaries. Tunnel spectra of this system reveal a previously unknown adiabatic shift of QW resonances due to lateral variations of the electronic reflection phase at the buried interface. With this effect, lateral distribution of the subsurface reflection phase can be probed, using scanning tunneling microscopy.

Reaction of metallotetraphenylporphyrins on hydroxyl-modified silver colloid and Ag2O colloid by surface-enhanced Raman scattering

This paper reports a novel reaction of metallotetraphenylporphyrins on hydroxyl-modified silver colloid and Ag2O colloid. Surface-enhanced Raman spectra of Ag(II) and Cu(II) complexes of tetraphenylporphyrin (TPP) adsorbed on the hydroxyl-modified Ag colloid and Ag2O colloid have been studied. The time-dependent SERS spectra of MTPP (M = Ag, Cu) on hydroxyl-modified Ag colloid were recorded and dramatic change on SERS spectra was observed. The final spectra were found to be strikingly different from the corresponding normal Raman spectra (NRS), with the appearance of new Raman bands at 1614. 1417, 947, 674 and 292 cm(-1). The UV-visible absorption spectrum of MTPP on hydroxyl-modified Ag colloid exhibits a broad shoulder near 460 nm. Similar spectral phenomena were also observed for AgTPP and CuTPP adsorbed on Ag2O colloid. The observed spectral alterations were ascribed to new species formation due to the irreducible oxidation of MTPP on the colloids.

[Molecular cloning of full length capsanthin/capsorubin synthase homologous gene from orange (Citrus sinensis)]

The complete sequence of orange homologous capsanthin/capsorubin synthase gene is 3788 bp long with a coding sequence of 1512 bp, which encodes a polypeptide of 503 amino acids. The 5' upstream sequence is 1721 bp long and the 3' downstream sequence is 555 bp long. The amino acid sequence of this gene is 78% and 69% identical to the genes from carrot and pepper, respectively. It is also partially homologous to plant neoxanthin synthase, lycopene beta-cyclase and lycopene epsilon cyclase genes. Isolation of the gene provides a framework for elucidation of the mechanisms involved in inability of citrus to produce capsanthin and capsorubin.

[Experimental study of mandibular reconstruction with Sr-HAP]

OBJECTIVE

Different ration of Sr-HAP was implanted in animals to study the bioreactions in order to prepare for the clinical applications in future.

METHODS

24 rabbits were divided into 3 groups for study.Bone defect of 6 x 12 x 4 mm was made at the mandibular angle of rabbits and Sr-HAP of different proportion (10%,5%,0%) was applied to repair the defect. One group of animals were killed at 1 month, 3 months, 6 months to evaluate the biologic capacity with anatomy, tetracycline fluorescent marker and ration histology.

RESULTS

Sr-HAP almost hadn't been rejected by hosts, and early after operation the new bone in the Sr-HAP was found with great quantities as the degradation of Sr-HAP much more than that in the pure HA, and the difference of bone quantity can be shown in statistics. New bone in 5% Sr-HAP looked more mature than those in 10% Sr-HAP with no statistic difference in quantity. Strong and bright fluorescent rings can be seen around Sr-HAP from the 3 months to 6 months.

CONCLUSION

(1) Sr-HAP has a better biocompatibility, biodegradation than pure HA and an excellent osteoinductivity. (2) The ration of strontium isn't the key influencing the new bone quantity,total new bone quantity maybe associated with the degree of biodegradation. (3) The existence of Sr-HAP improves the total new bone quantity and prolongs the period of new bone increasing.

Bistability in scanning tunneling spectroscopy of Ga-terminated Si(111)

Bistable electron transport, a phenomenon usually associated with double-barrier structures, has been observed with a conventional STM junction formed between a metal tip and a Ga-terminated Si(111) surface at 77 K. Large hysteresis loops appear in the current-voltage characteristics when electrons are injected from the tip to the surface. The turn-on bias varies from -3.1 to -4.0 V and shows an inverse dependence on the tip-sample distance, indicating a strong field effect. The turn-off bias, however, is essentially pinned at a conductance threshold of -2.7 V.

[CAT system and its application in training for manned space flight]

As aerospace missions get increasingly frequent and complex, training becomes ever more critical. Training devices in all levels are demanded. Computer-Aided Training (CAT) system, because its economic, efficient and flexible, is attracting more and more attention. In this paper, the basic factors of CAT system were discussed; the applications of CAT system in training for manned space flight were illustrated. Then we prospected further developments of CAT system.

Preferential activation of the complement system in the lower epidermis of patients with pemphigus vulgaris

Pemphigus vulgaris (PV) is an immune-mediated blistering skin disease characterized by acantholysis of the suprabasal epidermis and by IgG autoantibodies targeting a desmosomal component, desmoglein 3. IgG alone has been demonstrated to induce acantholysis in some experimental conditions. The role of the complement system in blister formation in PV remains controversial. We describe four consecutive patients with new-onset PV. The acantholytic process occurred in the lower epidermis and colocalized with deposition of complement C3 and the membrane attack complex C5b-9. The colocalization of complement deposition with the acantholytic process in the lower epidermis supports a role for the complement system in blister formation in PV.

Two distantly positioned PDZ domains mediate multivalent INAD-phospholipase C interactions essential for G protein-coupled signaling

Drosophila INAD, which contains five tandem protein interaction PDZ domains, plays an important role in the G protein-coupled visual signal transduction. Mutations in InaD alleles display mislocalization of signaling molecules of phototransduction which include the essential effector, phospholipase C-beta (PLC-beta), which is also known as NORPA. The molecular and biochemical details of this functional link are unknown. We report that INAD directly binds to NORPA via two terminally positioned PDZ1 and PDZ5 domains. PDZ1 binds to the C-terminus of NORPA, while PDZ5 binds to an internal region overlapping with the G box-homology region (a putative G protein-interacting site). The NORPA proteins lacking binding sites, which display normal basal PLC activity, can no longer associate with INAD in vivo. These truncations cause significant reduction of NORPA protein expression in rhabdomeres and severe defects in phototransduction. Thus, the two terminal PDZ domains of INAD, through intermolecular and/or intramolecular interactions, are brought into proximity in vivo. Such domain organization allows for the multivalent INAD-NORPA interactions which are essential for G protein-coupled phototransduction.

A bullous pemphigoid-like skin eruption after a chemical burn

Bullous pemphigoid is a blistering disorder characterized by antibody deposition in the lamina lucida of the basement membrane zone. In addition to the idiopathic form, there are many agents that have been implicated in inducing bullous pemphigoid or bullous pemphigoid-like lesions. We describe a patient who developed a bullous pemphigoid-like eruption after a chemical burn.

Visual sensitivity and interphotoreceptor retinoid binding protein in the mouse: regulation by vitamin A

Interphotoreceptor retinoid binding protein (IRBP) is a retinoid and fatty acid binding glycoprotein secreted by rod and cone photoreceptors in all vertebrates. IRBP is believed to serve as a carrier for retinoids in the bleaching and regeneration cycle of rhodopsin. IRBP protein has been found to be decreased in vitamin A-deprived rats; it is rapidly recovered after retinol repletion. To understand the mechanism for this recovery, we determined whether vitamin A affects transcription and translation of the IRBP gene. Wild-type and transgenic mice harboring the IRBP promoter-CAT reporter fusion gene were maintained on a retinol-deficient diet supplemented with retinoic acid (-A) or on a control diet (+A) for up to 60 wk postweaning. Some of the -A mice were given retinol repletion for 7 days (-A+A). Electroretinography analysis revealed alterations in waveform and a 2 log unit decrease in b-wave sensitivity in the -A mice over a broad range of stimulus wavelengths. Retinol repletion effected a full recovery. Immunochemistry showed a significant decrease in the immunogold-labeled IRBP between the retinal pigment epithelium and the outer segments of the -A mice compared with +A and -A+A mice. Northern blots showed no differences in the amounts of IRBP or CAT mRNA between these three treatment groups. These results suggest that the regulation of IRBP by retinol is not transcriptional.

Periorbital edema as an initial presentation of rosacea

Rosacea is a common dermatosis with a variety of clinical manifestations. The eyes are often affected. The most frequent ocular findings are blepharitis and conjunctivitis. We describe three patients with rosacea in whom periorbital edema was the initial presentation. This symptom may be confused with other dermatoses and may be refractory to conventional treatments for rosacea.

Control of Drosophila opsin gene expression by carotenoids and retinoic acid: northern and western analyses

In the fly, thorough retinoid deprivation is possible, to optimize investigation of the effects of vitamin A metabolites and retinoic acid (RA) on visual development. Retinoids had been found to control fly opsin gene transcription, though this finding was contested. Northern blots on Drosophila heads showed that mRNA of Rh1 (the predominant rhodopsin) was high in vitamin A replete controls, very low in deprived flies, and increased upon feeding carrot juice to deprived flies as early as 1 hr. Expression of the ribosomal protein 49 [rp49] gene (the control) was equal both in deprivation and in replacement. Recovery of Rh1 protein upon such carotenoid replacement followed, barely detectable on Western blots at 4 hr but conspicuous by 8 hr. Alternative chromophore deprivation with yeast-glucose food yielded flies with opsin mRNA on Northerns but not rhodopsin, as demonstrated by Western blots, spectrophotometry and the electroretinogram (ERG). Rh1's mRNA but not Rh1 protein resulted from rearing flies from egg to adult on the otherwise deprivational medium supplemented with RA or beef brain-heart infusion. By comparing results from these different media it was concluded that: [1] deprivation and replacement affect opsin gene transcription; and [2] contradictory conclusions were from chromophore deprivation which does not eliminate all retinoid dependent factors which could affect the opsin promoter. Preliminary evidence shows that carotenoid deprivation decreases two proteins relevant to visual function: [1] phospholipase C (PLC); and [2] Drosophila retinoid binding protein (DRBP).

Phospholipase C rescues visual defect in norpA mutant of Drosophila melanogaster

Mutations in the norpA gene of Drosophila melanogaster severely affect the light-evoked photoreceptor potential with strong mutations rendering the fly blind. The norpA gene has been proposed to encode phosphatidylinositol-specific phospholipase C (PLC), which enzymes play a pivotal role in one of the largest classes of signaling pathways known. A chimeric norpA minigene was constructed by placing the norpA cDNA behind an R1-6 photoreceptor cell-specific rhodopsin promoter. This minigene was transferred into norpAP24 mutant by P-element-mediated germline transformation to determine whether it could rescue the phototransduction defect concomitant with restoring PLC activity. Western blots of head homogenates stained with norpA antiserum show that norpA protein is restored in heads of transformed mutants. Moreover, transformants exhibit a large amount of measurable PLC activity in heads, whereas heads of norpAP24 mutant exhibit very little to none. Immunohistochemical staining of tissue sections using norpA antiserum confirm that expression of norpA protein in transformants localizes in the retina, more specifically in rhabdomeres of R1-6 photoreceptor cells, but not R7 or R8 photoreceptor cells. Furthermore, electrophysiological analyses reveal that transformants exhibit a restoration of light-evoked photoreceptor responses in R1-6 photoreceptor cells, but not in R7 or R8 photoreceptor cells. This is the strongest evidence thus far supporting the hypothesis that the norpA gene encodes phospholipase C that is utilized in phototransduction.

Regeneration of simon poplar (Populus simonii) from protoplast culture

Simon poplar (Populus simonii) protoplasts were isolated from suspension cells, with protoplast yield of 3.8×10(7) g(-1) F. W. They were cultured in a K8P liquid medium containing 13.57μM 2,4-D, 1.07μM NAA and 0.93 μM KT. Protoplast culture was influenced by the plating density, osmotic pressure, and the sources and amounts of nitrogen and carbon in the culture medium. Multiple shoots were produced from protoplast-derived callus after culture on MS medium containing 4.44 μM BA, 2.32μM KT, 2.28 μM ZT, and 0.54μM NAA. Shoots 2-3 cm in height were isolated from the calli and rooted on 1/2 MS medium. After transplantation into pots, the regenerated plants grew vigorously in greenhouse.