The absence of piezoelectricity in silicon makes direct electro-mechanical applications of this mainstream semiconductor impossible. Integrated electrical control of the silicon mechanics, however, ...would open up new perspectives for on-chip actuorics. Here, we combine wafer-scale nanoporosity in single-crystalline silicon with polymerization of an artificial muscle material inside pore space to synthesize a composite that shows macroscopic electrostrain in aqueous electrolyte. The voltage-strain coupling is 3 orders of magnitude larger than the best-performing ceramics in terms of piezoelectric actuation. We trace this huge electroactuation to the concerted action of 100 billions of nanopores per square centimetre cross-section and to potential-dependent pressures of up to 150 atmospheres at the single-pore scale. The exceptionally small operation voltages (0.4-0.9 V) along with the sustainable and biocompatible base materials make this hybrid promising for bio-actuator applications.
The nuclear factor-kappaB (NF-kappaB) transcription factor system is a crucial component that controls several important biological functions, thus raising the need for mechanisms that ensure the ...correct termination of its activity. Here, we identify a new phosphorylation/ubiquitination switch in the NF-kappaB network that controls the stability of the transactivating p65 subunit. Tumour necrosis factor-induced phosphorylation of p65 at Ser468 allows binding of COMMD1 and cullin 2, components of a multimeric ubiquitin ligase complex mediating p65 ubiquitination. Mutation of p65 at Ser468 largely prevents p65 ubiquitination and proteasomal degradation. Inducible p65 elimination is restricted to a subset of NF-kappaB target genes such as Icam1. Accordingly, chromatin immunoprecipitation experiments reveal the selective recruitment of Ser468-phosphorylated p65 and COMMD1 to the Icam1 promoter. Phosphorylation of p65 at Ser468 leads to ubiquitin/proteasome-dependent removal of chromatin-bound p65, thus contributing to the selective termination of NF-kappaB-dependent gene expression.
We have developed an immunochemiluminometric assay (ICMA) with two monoclonal antibodies for the N-terminal sequence of human parathyroid hormone (hPTH). One monoclonal antibody (A1–70) was ...physically adsorbed onto polystyrene beads, the other (B1–70) was labelled with acridinium ester and synthetic hPTH (1–38) was used as standard. This assay has cross-reactions with synthetic hPTH (1–34) and hPTH (1–84) but no cross-reactions with hPTH (4–16), (28–48), (39–84), (44–68), (53–84) and hPTH-rP (1–86). The assay detection limit is 0.4 pmol/l. The normal range is 1.3–12 pmol/l based on 72 normal volunteers. About 91% of study patients (
n = 58) with surgically proven primary hype-rparathyroidism (1°HPT) had PTH values above normal and one of them showed a low normal intact PTH value but elevated PTH values with use of this assay. After immunoabsorption of plasma samples from patients with secondary hyperparathyroidism (2°HPT) on hemodialysis with polystyrene beads containing antibodies against hPTH (39–84), some patients still showed significant amounts of PTH in this new ICMA but not intact PTH. The data reveal that significant amounts of amino-terminal immunoreactive PTH fragments rarely exist in 1°HPT but are present in some patients with 2°HPT. The major advantage of this assay is to measure both amino-terminal PTH fragments and intact PTH with no interference from carboxy-terminal PTH fragments because two anti-N-terminal hormone sequence monoclonal antibodies are used.
PDF
