Isolation and structure/activity features of halomon-related antitumor monoterpenes from the red alga Portieria hornemannii

Ten halogenated monoterpenes (2-6 and 8-12) related to the novel antitumor compound halomon (1) or to the carbocyclic analog 7 have been isolated from different geographic collections of the red alga, Portieria hornemannii. Structures were assigned to the basis of spectral analyses (primarily NMR and MS). The absolute configuration of isohalomon (2) was further established by X-ray crystallography. The compounds were comparatively evaluated alongside 1 and 7 in the U.S. National Cancer Institute's in vitro human tumor cell line screening panel. The results provide some interesting initial insights into the structure/activity relationships in this series.     

Co-Stimulation of Oxytocin and Arginine-Vasopressin Receptors Affect Hypothalamic Neurospheroid Size

Oxytocin (OXT) is a neuropeptide involved in a plethora of behavioral and physiological processes. However, there is a prominent lack of 3D cell culture models that investigate the effects of OXT on a cellular/molecular level. In this study, we established a hypothalamic neuronal spheroid model to investigate the cellular response in a more realistic 3D setting. Our data indicate that the formation of spheroids itself does not alter the basic characteristics of the cell line and that markers of cellular morphology and connectivity are stably expressed. We found that both OXT and arginine vasopressin (AVP) treatment increase spheroid size (surface area and volume), as well as individual nucleus size, which serves as an indicator for cellular proliferation. The cellular response to both OXT and AVP seems mainly to be mediated by the AVP receptor 1a (V1aR); however, the OXT receptor (OXTR) contributes significantly to the observed proliferative effect. When we blocked the OXTR pharmacologically or knocked down the OXTR by siRNA, the OXT- or AVP-induced cellular proliferation decreased. In summary, we established a 3D cell culture model of the neuronal response to OXT and AVP and found that spheroids react to the treatment via their respective receptors but also via cross-talk between the two receptor types.     

A sub-0.5 μm bilevel lithographic process using the deep-UV electron-beam resist p(si-cms)

Optimization of the deep-UV and electron-beam lithographic properties of a copolymer of trimethylsilylmethyl methacrylate (SI) and chloromethylstyrene (CMS), P(SI-CMS), within a weight average molecular weight range of 1.4 to 4.1 × 10⁵ and 90 to 93 mole percent SI composition has been achieved. The solubility behavior of P(SI-CMS) resist was examined using the Hansen 3-dimensional solubility parameter model and dissolution rate measurements. Swelling of the resist has been minimized through the identification of a single component developer (2-propanol) and rinse (water) system. For the material containing 90 mole percent SI (14.9 weight percent Si) and M?_ω = 1.4 × 10⁵, the sensitivity to 248 nm radiation is 65 mJ/cm² and to electron-beam exposure is 3.4 μC/cm² at 20 kV. This material Is applicable to bilevel lithographic processes, and the O₂ reactive ion etching (RIE) rate is 16 times slower than standard hard-baked photoresist. Using a He/O₂(60/40) RIE pattern transfer process, 0.4 μm line/space patterns have been resolved in a 1.3 μm bilayer structure for deep-UV exposures, and 0.25 μm imaging has been demonstrated in a 0.7 μm thick planarizing layer using electron beam irradiation. The loss in linewidth associated with the 0.25 μm process is ～0.04 μm.     

Time versus space trade-offs for rendezvous in trees

Two identical (anonymous) mobile agents start from arbitrary nodes of an unknown tree and have to meet at some node. Agents move in synchronous rounds: in each round an agent can either stay at the current node or move to one of its neighbors. We consider deterministic algorithms for this rendezvous task. The main result of this paper is a tight trade-off between the optimal time of completing rendezvous and the size of memory of the agents. For agents with $k$ memory bits, we show that optimal rendezvous time is $\Theta (n+n^2/k)$ in $n$ -node trees. More precisely, if $k \ge c\log n$ , for some constant $c$ , we design agents accomplishing rendezvous in arbitrary trees of size $n$ (unknown to the agents) in time $O(n+n^2/k)$ , starting with arbitrary delay. We also show that no pair of agents can accomplish rendezvous in time $o(n+n^2/k)$ , even in the class of lines of known length and even with simultaneous start. Finally, we prove that at least logarithmic memory is necessary for rendezvous, even for agents starting simultaneously in a $n$ -node line.     

Backscattered light confocal imaging of intracellular MTT-formazan crystals

Metabolically active animal and plant cells reduce MTT tetrazolium salt to a corresponding nonfluorescent formazan. Reduction of MTT by viable cells is exploited in a number of tests widely used in biological research. The aim of this study was to optimize a microscopy method of detecting small crystals of MTT-formazan formed in intact cells maintained in in vitro cultures. We examined scattering properties of small intracellular crystals of MTT formazan and found that the efficiency of light scattering was dependent on wavelength. Small (<3 microm) crystals of MTT-formazan, formed in viable cells, scattered red, but not blue, light. Large crystals, which are formed later at a stage when cells begin to lose viability, scattered both red and blue light. We conclude that optimal detection of early stages of crystallization of MTT-formazan in living cells is possible using confocal microscopy of red, but not blue, scattered light. High contrast and resolution of images can be achieved by filtering out interference effects in the frequency domain.     

Pinning performance of (Nd,Eu,Gd)-123 superconductors: Comparison of melt-textured pellet and single crystal

We studied pinning homogeneity and the content fluctuation of light rare earth ions in a (Nd_0.33Eu_0.38Gd_0.28)Ba₂Cu₃O_y melt-textured (MT) pellet 16 mm in diameter, doped by 0.035 mol% ZnO. The pinning performance was compared to that of the recently grown (Nd_0.33Eu_0.2Gd_0.47)Ba₂Cu₃O_y single crystal. While magnetic properties of most test samples cut from the MT pellet were surprisingly uniform, two samples from the pellet center behaved significantly different. This anomaly was found to correlate with the significant departure of the Eu:Nd ratio from the average. Nearly all MT samples showed a high-field shoulder on J_c(B) curve that was attributed to the pinning effect of a nanoscopic correlated lamellar substructure filling channels between regular twin boundaries. As a result, the irreversibility field at 77 K reached in all 20 measured MT samples 9 T. In the single crystal no high-field J_c(B) shoulder was observed, and the irreversibility field at 77 K was about 6 T. The strip-like structure observed on the crystal surface was evidently of another origin than the lamellar substructure in the MT samples and did not significantly contribute to vortex pinning. The secondary peak in J_c(B) of the single crystal was quite strong, showing a well set point-like disorder. All magnetic characteristics of the single crystal were strongly affected by twin-plane channeling effect.     

FEM simulation of aluminium extrusion through two-hole multi-step pocket dies

Multi-hole pocket dies are a type of extrusion tooling setup commonly used across the aluminium extrusion industry for efficient production of solid aluminium profiles. Such dies are designed on the basis of experience and corrected after a number of trial extrusion runs before becoming usable. Computer simulation based on the finite element method (FEM) is in principle capable of predicting metal flow through the dies designed, but it is yet a huge technological challenge to simulate the extrusion process to produce profiles of industrial significance. The present research was attempted to investigate the effect of steps in the die pocket on metal flow to produce two chevron profiles with unequal thicknesses through two-hole dies, by means of 3D FEM simulation of extrusion in the transient state. The results showed that the pocket step could be effectively used to balance metal flow. Extrusion experiments validated the predictions of metal flow, extrudate temperature and the pressure required for extrusion through the pocket dies with three different designs. 3D FEM was demonstrated to be a powerful tool in optimising die design and decreasing the number of trial extrusion runs.     

Fluorescent amino-substituted squaraine probes for bovine serum albumin

The synthesis and spectroscopic properties of fluorescent amino-substituted squaraine dyes have been presented. The interaction between bovine serum albumin (BSA) and fluorescence probes derived from squaric acid was studied by UV-vis and fluorescence spectroscopies. The Benesi–Hildebrand, Lehrer, and Stern–Volmer equations were used to present the influence of BSA concentration on the binding constant for the process of association with squaraine dyes, as well as the effect of the concentration of fluorescence probes on the quenching process. It was also shown that the interaction between BSA and squaraine dyes is spontaneous. The number of binding sites to bovine serum albumin for a series of squaraine dyes has also been calculated.