Post-traumatic hormonal disturbances: prolactin as a link between head injury and enhanced osteogenesis

The local recurrence rate after rectal cancer surgery is discussed as related to conventional and total mesorectal excision (TME) techniques. Studies now show that the wide variation in results between centers and among surgeons depends, at least in part, on differences in surgical technique. We conclude that local tumor recurrence rate is lower after TME than after conventional surgery and emphasize the importance of a standardized macroscopic evaluation of the resected specimen. Population-based registration to evaluate the quality of surgery is recommended. It is also suggested that randomized studies on adjuvant treatment for rectal cancer should include a "surgery only" arm when a local tumor recurrence rate of 10% or less is being studied. Until such investigations are performed, we conclude that the role for adjuvant treatment is questionable and that TME surgery is preferred as the treatment option for Stage T1-T3 rectal cancers.     

Microstructure and mechanical properties of rapidly solidified Fe-25%Cr-5%Al ribbons produced by planar flow casting

Catalyst substrate foils of the highly oxidation resistant Fe-25Cr-5Al alloy (mass contents in %) with a thickness ranging from 40 to 180 μm have been produced by planar flow casting. The rapidly solidified ribbons showed a monophase ferritic microstructure of columnar grains. The grain size determined over a section parallel to the ribbon wheel side ranged from 5 μm for the thin ribbons (40 μm) to 18 μm for the thicker ones {180 μm). This anisotropic columnar solidification microstructure exhibits a strong <100> fiber texture, with the fiber axis nearly perpendicular to the plane of the ribbon. The position of the maximum in the pole figure was tilted from the center point toward the casting direction. Results of uniaxial tensile tests showed that only the yield stress data of the ribbons in the as-cast condition are reproducible, whereas the ultimate tensile strength and the elongation to failure data show a wide scatter band. The fracture mode exhibits ductile features such as glide bands and dimples.     

Modeling small-scale resistance spot welding machine dynamics for process control

Electrode displacement is generally regarded as a variable that can provide real-time information useful for monitoring and controlling resistance spot welding (RSW) process quality. However, in small-scale RSW production, it is difficult to measure the displacement because its magnitude is very small. By contrast, force signals are relatively large and thus are less susceptible to measurement noise. In this article, an empirical model is proposed to simulate the dynamics of an SSRSW head with the objective of calculating electrode displacement from the variation of electrode clamping force measured during welding. The parameters in the model were determined by fitting experimental force and displacement signals with polynomials and then performing an optimization search for parameters of first-order dynamic models. To verify the models’ accuracy, they were subsequently applied to simulate the electrode displacement curves of welds with expulsion and without expulsion. The calculated displacement curves agreed well with experimental measurements, and the occurrence of expulsion was clearly indicated by the model predictions. A more comprehensive model is under construction with an objective to eliminate displacement sensor in the monitoring and control of SSRSW process.     

Structure–Transport Correlation Reveals Anisotropic Charge Transport in Coupled PbS Nanocrystal Superlattices

The assembly of colloidal semiconductive nanocrystals into highly ordered superlattices predicts novel structure-related properties by design. However, those structure–property relationships, such as charge transport depending on the structure or even directions of the superlattice, have remained unrevealed so far. Here, electric transport measurements and X-ray nanodiffraction are performed on self-assembled lead sulfide nanocrystal superlattices to investigate direction-dependent charge carrier transport in microscopic domains of these materials. By angular X-ray cross-correlation analysis, the structure and orientation of individual superlattices is determined, which are directly correlated with the electronic properties of the same microdomains. By that, strong evidence for the effect of superlattice crystallinity on the electric conductivity is found. Further, anisotropic charge transport in highly ordered monocrystalline domains is revealed, which is attributed to the dominant effect of shortest interparticle distance. This implies that transport anisotropy should be a general feature of weakly coupled nanocrystal superlattices.     

Copulation releaser pheromone in body scales of female whitemarked tussock moth,Orgyia leucostigma (Lepidoptera: Lymantriidae): Identification and behavioral role

The copulatory behavior of the male whitemarked tussock moth,Orgyia leucostigma, was released by extracts of female body scales applied to rubber septum models baited with a female sex pheromone gland. The major compounds in the scale extracts were identified by GC-MS as a series ofn-alkanes from C-21 to C-29. Of these,n-tricosane,n-tetracosane,n-pentacosane, andn-heptacosane, applied at 10 ng/septum, caused significantly more males to attempt copulation than hexane-treated controls. Mixtures of then-alkanes, resembling the composition in the scale extracts, were no better than the two most active alkanes,n-tetracosane andn-pentacosane, alone. The releaser effect of then-alkanes was dose dependent. EAG responses to the identifiedn-alkanes were small suggesting, along with the behavioral observations, that their perception occurred at very close range. Other factors releasing male copulatory behavior are discussed.     

Abwasserüberwachung als vorbeugender Gewässerschutz

Monitoring of liquid effluents as preventative protection of natural bodies of water. One possibility to improve the safety of river water cooling systems is to control the river water side of the cooling system continuously by process analyzers. In this way, leakages in cooling systems can be recognized earlier and the amount of products which contaminate the river water can be minimized. The aim of this article is to inform the user of water cooling systems about the process analyzers which are available. A second aim is to help him to decide which of these analyzers is the best for his measuring problem.     

Nerve growth factor promotes activation of the alpha, beta and gamma isoforms of protein kinase B in PC12 pheochromocytoma cells

The activation of phosphatidylinositol (PtdIns) 3-kinase is considered to be a key event occurring after stimulation of cells with growth factors. The proto-oncogenic protein kinase B (PKB; also known as RAC protein kinase or Akt) has recently been shown to be a downstream target of PtdIns 3-kinase and may be involved in cell survival. We therefore asked whether stimulation of neuronal cells with nerve growth factor (NGF), on which certain types of neurons are dependent for survival, causes activation of PKB. Stimulation of serum-starved PC12 rat pheochromocytoma cells with NGF caused an increase of up to 14-fold in PKB activity. This activation was detected within 1 min of stimulation and occurred at NGF concentrations that are consistent with TrkA-mediated signaling. PKB activation was accompanied by a decrease in electrophoretic mobility of the kinase, which is characteristic of phosphorylation. Both PKB activation and mobility changes were prevented by wortmannin, indicating the upstream involvement of PtdIns 3-kinase in these events. Analyses employing isoform-specific antibodies for immunoprecipitation suggested that all three isoforms of PKB (alpha, beta and gamma) are activated in response to NGF. G-protein-coupled-receptor agonists, lysophosphatidic acid (lyso-PtdH) and thrombin, which induce rapid neurite retraction, neither stimulated PKB activity, nor affected NGF-induced or insulin-induced kinase activation. Wortmannin treatment did not prevent neurite retraction induced by lyso-PtdH or thrombin. These data suggest that PtdIns 3-kinase and PKB are not involved in cytoskeletal changes mediated by the small GTPase Rho.     

Modified coin cells for in situ Raman spectroelectrochemical measurements of Li(x)V2O5 for lithium rechargeable batteries

In situ Raman spectroscopy is an extremely valuable technique for investigating fundamental reactions that occur inside lithium rechargeable batteries. However, specialized in situ Raman spectroelectrochemical cells must be constructed to perform these experiments. These cells are often quite different from the cells used in normal electrochemical investigations. More importantly, the number of cells is usually limited by construction costs; thus, routine usage of in situ Raman spectroscopy is hampered for most laboratories. This paper describes a modification to industrially available coin cells that facilitates routine in situ Raman spectroelectrochemical measurements of lithium batteries. To test this strategy, in situ Raman spectroelectrochemical measurements are performed on Li//V2O5 cells. Various phases of Li(x)V2O5 could be identified in the modified coin cells with Raman spectroscopy, and the electrochemical cycling performance between in situ and unmodified cells is nearly identical.     

Spectroscopic investigation of proton-conducting, cross-linked linear poly(ethylenimine) hydrochloride membranes

The degree of cross-linking for linear poly(ethylenimine) hydrochloride, cross-linked using malonaldehyde generated in situ, was determined from the ratio of the cross-link to backbone hydrogens obtained using ¹H NMR spectroscopy. The a.c. conductivity is highest at intermediate degrees of cross-linking (ca. 0.45), approximately 1 × 10⁻³ S/cm at room temperature and 75% relative humidity. IR and Raman spectroscopy were used to characterize the cross-linked network. The presence of the β-aminoethenyliminium cross-linker units can be identified through a series of bands between 1570 and 1640 cm⁻¹. Other changes in the spectra identified as a function of degree of cross-linking are discussed.