Biosorption of Phosphate Ion on Albizia Lebbeck Seed Pod with and Without Organic Acid Modification

This study uses batch experiment to compare the binding efficiency of phosphate onto Albizia lebbeck (ALB) pod with and without citric acid (CALB) or tartaric acid (TALB) modification. The residual phosphate concentration was analyzed using ascorbic acid method and the generated data were fitted into equilibrium isotherms and kinetics models. Intra-particle diffusion model was used to describe the biosorption mechanism. Characterization by FTIR spectroscopy and SEM shows that modification was successful. The maximum biosorption capacity occurred at biosorbent dosage of 0.5 g for ALB and 1.0 g for CALB and TALB. At optimum pH for each biosorbents, phosphate biosorption capacity is in the order ALB>CALB>TALB. Equilibrium time of 90, 150 and 60 minutes were recorded for phosphate on ALB, CALB and TALB respectively. The biosorption capacity increases as the initial anion concentration increases with highest biosorption capacity of 5.296 mg/g for ALB. Langmuir isotherm describes CALB data while TALB data fits Freundlich. Results from this study suggest that unmodified Albizia lebbeck can be used as a low-cost, highly-efficient biosorbent for phosphate removal in effluents

Equilibrium, Kinetic and Thermodynamic Studies of Biosorption of Methylene Blue on Goethite Modified Baobab Fruit Pod ( Adansonia Digitata L.)

Methylene Blue (MB) was adsorbed from aqueous solution using Baobab (Adansonia digitata L.) fruit pod and its goethite modified form. Adsorbents were characterized using Fourier Transform-Infra Red (FT-IR) spectroscopy and Scanning Electron Microscopy (SEM). Batch experiments were conducted at room temperature (26.8 \ub0C) and the adsorption data were fitted using Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherms. Also, kinetic data was fitted using Pseudo-first order, pseudo-second order, Elovich and intra-particle diffusion models. Goethite modified baobab (GMB) appeared to have a coarse microporous surface with smoother surface and larger pore volumes compared to unmodified baobab (UB). The \u2013C=O band was observed at 1631 and 1636 cm-1 for UB and GMB. The \u2013OH band was observed at 3447.00 cm-1 and 3442 cm-1 for UB and GMB respectively. Langmuir model was suitable for describing the adsorption data of UB with R2 of 0.9293 while Temkin model was best for fitting adsorption data of MB on GMB with R2 of 0.9691. However, maximum adsorption capacity was obtained with Freundlich adsorption isotherm (15.4253 and 43.1301 mg/g for UB and GMB respectively). The maximum biosorption were 8.98 mg/g and 9.86 mg/g for UB and GMB respectively at pH 10. Pseudo-second-order kinetic model best fitted the kinetic data with R2 values of 0.9968 and 0.9993 for UB and GMB, \uf044Ho values were 83.123 KJ/mol and 361.094 KJ/mol for UB and GMB, while \uf044So values were 3.084 J/mol/K and 1.765 J/mol/K for UB and GMB respectively. GMB adsorbed more of MB than UB and the process was endothermic

Efficiency of siRNA delivery by lipid nanoparticles is limited by endocytic recycling

Despite substantial efforts to understand the interactions between nanoparticles and cells, the cellular processes that determine the efficiency of intracellular drug delivery remain largely unclear. Here we examined cellular uptake of siRNA delivered in lipid nanoparticles (LNPs) using cellular trafficking probes in combination with automated high-throughput confocal microscopy as well as defined perturbations of cellular pathways paired with systems biology approaches to uncover protein-protein and protein-small molecule interactions. We show that multiple cell signaling effectors are required for initial cellular entry of LNPs through macropinocytosis, including proton pumps, mTOR, and cathepsins. SiRNA delivery is substantially reduced as ≅70% of the internalized siRNA undergoes exocytosis through egress of LNPs from late endosomes/lysosomes. Niemann Pick type C1 (NPC1) is shown to be an important regulator of the major recycling pathways of LNP-delivered siRNAs. NPC1-deficient cells show enhanced cellular retention of LNPs inside late endosomes/lysosomes and increased gene silencing of the target gene. Our data suggests that siRNA delivery efficiency might be improved by designing delivery vehicles that can escape the recycling pathways

S1 Constrains S4 in the Voltage Sensor Domain of Kv7.1 K+ Channels

Voltage-gated K+ channels comprise a central pore enclosed by four voltage-sensing domains (VSDs). While movement of the S4 helix is known to couple to channel gate opening and closing, the nature of S4 motion is unclear. Here, we substituted S4 residues of Kv7.1 channels by cysteine and recorded whole-cell mutant channel currents in Xenopus oocytes using the two-electrode voltage-clamp technique. In the closed state, disulfide and metal bridges constrain residue S225 (S4) nearby C136 (S1) within the same VSD. In the open state, two neighboring I227 (S4) are constrained at proximity while residue R228 (S4) is confined close to C136 (S1) of an adjacent VSD. Structural modeling predicts that in the closed to open transition, an axial rotation (∼190°) and outward translation of S4 (∼12 Å) is accompanied by VSD rocking. This large sensor motion changes the intra-VSD S1–S4 interaction to an inter-VSD S1–S4 interaction. These constraints provide a ground for cooperative subunit interactions and suggest a key role of the S1 segment in steering S4 motion during Kv7.1 gating

A functional Kv1.2-hERG chimaeric channel expressed in Pichia pastoris.

Members of the six-transmembrane segment family of ion channels share a common structural design. However, there are sequence differences between the members that confer distinct biophysical properties on individual channels. Currently, we do not have 3D structures for all members of the family to help explain the molecular basis for the differences in their biophysical properties and pharmacology. This is due to low-level expression of many members in native or heterologous systems. One exception is rat Kv1.2 which has been overexpressed in Pichia pastoris and crystallised. Here, we tested chimaeras of rat Kv1.2 with the hERG channel for function in Xenopus oocytes and for overexpression in Pichia. Chimaera containing the S1-S6 transmembrane region of HERG showed functional and pharmacological properties similar to hERG and could be overexpressed and purified from Pichia. Our results demonstrate that rat Kv1.2 could serve as a surrogate to express difficult-to-overexpress members of the six-transmembrane segment channel family

Globular cluster systems and galaxy formation

Globular clusters are compact, gravitationally bound systems of up to a million stars. The GCs in the Milky Way contain some of the oldest stars known, and provide important clues to the early formation and continuing evolution of our Galaxy. More generally, GCs are associated with galaxies of all types and masses, from low-mass dwarf galaxies to the most massive early-type galaxies which lie in the centres of massive galaxy clusters. GC systems show several properties which connect tightly with properties of their host galaxies. For example, the total mass of GCs in a system scales linearly with the dark matter halo mass of its host galaxy. Numerical simulations are at the point of being able to resolve globular cluster formation within a cosmological framework. Therefore, GCs link a range of scales, from the physics of star formation in turbulent gas clouds, to the large-scale properties of galaxies and their dark matter. In this Chapter we review some of the basic observational approaches for GC systems, some of their key observational properties, and describe how GCs provide important clues to the formation of their parent galaxies.Comment: 32 pages, 6 figures. Accepted for publication in the book "Reviews in Frontiers of Modern Astrophysics: From Space Debris to Cosmology" (eds Kabath, Jones and Skarka; publisher Springer Nature) funded by the European Union Erasmus+ Strategic Partnership grant "Per Aspera Ad Astra Simul" 2017-1-CZ01-KA203-03556