Preparation of Mn-Zn Ferrites Having a Low Temperature Coefficient of Permeability

Substitutions of Ge, and to a lesser extent Ga, for Zn in manganese-zinc ferrite were found to increase the initial permeability (μ) from ∼200 to ∼1000. The relative temperature coefficient of permeability is very low (<0.02%) over the range -40° to +80°C. These desired properties are achieved without controlling the atmosphere during sintering und subsequent cooling provided rhat the utmo sphere contains ≥1 vol% 0₂ .     

Ionizable Lipid with Supramolecular Chemistry Features for RNA Delivery In Vivo

Lipid nanoparticles (LNPs) and ribonucleic acid (RNA) technology are highly versatile tools that can be deployed for diagnostic, prophylactic, and therapeutic applications. In this report, supramolecular chemistry concepts are incorporated into the rational design of a new ionizable lipid, C3-K2-E14, for systemic administration. This lipid incorporates a cone-shaped structure intended to facilitate cell bilayer disruption, and three tertiary amines to improve RNA binding. Additionally, hydroxyl and amide motifs are incorporated to further enhance RNA binding and improve LNP stability. Optimization of messenger RNA (mRNA) and small interfering RNA (siRNA) formulation conditions and lipid ratios produce LNPs with favorable diameter (<150 nm), polydispersity index (<0.15), and RNA encapsulation efficiency (>90%), all of which are preserved after 2 months at 4 or 37 °C storage in ready-to-use liquid form. The lipid and formulated LNPs are well-tolerated in animals and show no deleterious material-induced effects. Furthermore, 1 week after intravenous LNP administration, fluorescent signal from tagged RNA payloads are not detected. To demonstrate the long-term treatment potential for chronic diseases, repeated dosing of C3-K2-E14 LNPs containing siRNA that silences the colony stimulating factor-1 (CSF-1) gene can modulate leukocyte populations in vivo, further highlighting utility.     

Machine tunnelling in the twenty-first century

In the coming decades, versatile machines will be developed that will be capable of boring through both hard rock and wet soil conditions. These machines will be able to pass from hard rock through a water-filled fault zone and in a soil tunnel under a river: they will make the transition with ease into a mixed face of rock and boulders. Machines will incorporate state-of-the-art electronics that will give the operator the information needed to maintain a high level of availability and utilization. This will be an important factor in reducing machine tunnelling costs. The new materials that will be used to build cutters will increase cutter life while reducing costs of tunnelling in the hardest rocks. New types of machines will cut non-circular tunnels in hard rock, providing highway and railroad builders the advantage of high-speed machine tunnelling. There will remain for the twenty-first century unlimited opportunities for development to solve difficult tunnelling problems such as undersea tunnels in weak rock conditions. If tunnel owners and builders utilize the resources of the machine developers effectively, technology will be developed rapidly and will dramatically reduce the cost of underground construction.     

Effects of aryl hydrocarbon receptor-mediated early life stage toxicity on lake trout populations in Lake Ontario during the 20th century

Lake trout embryos and sac fry are very sensitive to toxicity associated with maternal exposures to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and structurally related chemicals that act through a common aryl hydrocarbon receptor (AHR)-mediated mechanism of action. The loading of large amounts of these chemicals into Lake Ontario during the middle of the 20th century coincided with a population decline that culminated in extirpation of this species around 1960. Prediction of past TCDD toxicity equivalence concentrations in lake trout eggs (TEC(egg)s) relative to recent conditions required fine resolution of radionuclide-dated contaminant profiles in two sediment cores; reference core specific biota--sediment accumulation factors (BSAFs) for TCDD-like chemicals in lake trout eggs; adjustment of the BSAFs for the effect of temporal changes in the chemical distributions between water and sediments; and toxicity equivalence factors based on trout early life stage mortality. When compared to the dose-response relationship for overt early life stage toxicity of TCDD to lake trout, the resulting TEC(egg)s predict an extended period during which lake trout sac fry survival was negligible. By 1940, following more than a decade of population decline attributable to reduced fry stocking and loss of adult lake trout to commercial fishing, the predicted sac fry mortality due to AHR-mediated toxicity alone explains the subsequent loss of the species. Reduced fry survival, associated with lethal and sublethal adverse effects and possibly complicated by other environmental factors, occurred after 1980 and contributed to a lack of reproductive success of stocked trout despite gradually declining TEC(egg)s. Present exposures are close to the most probable no observable adverse effect level (NOAEL TECegg = 5 pg TCDD toxicity equivalence/g egg). The toxicity predictions are very consistent with the available historical data for lake trout population levels in Lake Ontario, stocking programs, and evidence for recent improvement in natural reproduction concomitant with declining levels of persistent bioaccumulative chemicals in sediments and biota.     

FAILURE OF MERCURIC CHLORIDE TO SELECTIVELY INHIBIT β-AMYLASE IN SORGHUM MALT

Mercuric chloride has been reported to be a suitable reagent for the determination of α-amylase activity in sorghum malt, based on its ability to selectively inhibit β-amylase. In this re-investigation, the α- and β-amylase activities of eight sorghum malts were determined after treatment of malt extracts with various concentrations of mercuric chloride. At a malt: mercuric chloride ratio of 8.3 × 10³: 1, incomplete inhibition of β-amylase activity, as measured by the Betamyl assay, occurred in all extracts. However, this concentration resulted in significant inhibition of α-amylase activity in all extracts, as measured by both the Ceralpha assay and the Phadebas assay. In addition, α-amylase activity was found to be significantly inhibited at malt: mercuric chloride ratios as low as 1.0 × 10⁵: 1, when measured by the AmyloZyme assay. These findings do not support the original report that a malt: mercuric chloride ratio of 4.0 × 10³: 1 will selectively inhibit β-amylase in sorghum malt. Furthermore, in this context it should be emphasised that the original report was based upon inhibition studies conducted on β-amylase derived from barley, not sorghum malt .