A purification system for 64Cu produced by a biomedical cyclotron for antibody PET imaging

Ion exchange is a simple and efficient method for separating no-carrier-added ⁶⁴Cu from an irradiated Ni target. We developed a semi-automated two-round ⁶⁴Cu separation system equipped with a strong-base anion exchange resin column. We first verified the efficiency of the system using a non-radioactive substitute consisting of 25 mg of Ni and 127 ng of Cu, and confirmed that Cu was completely eluted at the second round of the separation step. After the bombardment, separation of ⁶⁴Cu from the Ni target was achieved with high radiochemical purity. ⁶⁴Cu produced and separated in this study had an extremely low level of Ni impurity. It could be used for labeling monoclonal antibodies for antibody positron emission tomography imaging and synthesizing radiopharmaceuticals.     

Self‐assembly of Functionalized Gold Nanoparticles with Rigid and Flexible Multifunctional Linkers

The interparticle spacing of carboxyl functionalized gold nanoparticles (Au‐COOH) were mediated by rigid crosslinkers, octa(3‐aminopropyl)octasilsesquioxane (POSS‐NH₃ ⁺) and poly(amidoamine) dendrimer terminated with hydroxyl groups (PAMAM‐OH), and a flexible polymeric linker, poly(hexanul viologen) (6‐VP). Regular interparticle spacing was achieved by utilizing POSS‐NH₃ ⁺ and PAMAM‐OH dendrimer as cross linkers, whereas size growth of Au‐COOH was observed featuring no interparticle spacing by utilizing 6‐VP as the crosslinker.     

The Role of Hydrogen Bond and Crystal Solvent in the Solid-state (β-α) Photoisomerization of Novel 2-(N-phenylcarbamoyl)ethyl Cobaloxime Complexes [1]

Abstract

The 2-(phenylcarbamoyl)ethyl group bonded to the cobalt atom in cobaloxime complexes was isomerized on exposure to visible light in the solid-state. The three complexes with different amines as axial base ligands were prepared and their crystal structures were determined by X-ray analysis. The reaction rates in the solid-state were mainly affected by the hydrogen bonds of the reactive group with the neighboring molecules and the occupation of crystal solvent molecules around the reactive group.     

Heavy element stable isotope ratios : analytical approaches and applications

Continuous developments in inorganic mass spectrometry techniques, including a combination of an inductively coupled plasma ion source and a magnetic sector-based mass spectrometer equipped with a multiple-collector array, have revolutionized the precision of isotope ratio measurements, and applications of inorganic mass spectrometry for biochemistry, geochemistry, and marine chemistry are beginning to appear on the horizon. Series of pioneering studies have revealed that natural stable isotope fractionations of many elements heavier than S (e.g., Fe, Cu, Zn, Sr, Ce, Nd, Mo, Cd, W, Tl, and U) are common on Earth, and it had been widely recognized that most physicochemical reactions or biochemical processes induce mass-dependent isotope fractionation. The variations in isotope ratios of the heavy elements can provide new insights into past and present biochemical and geochemical processes. To achieve this, the analytical community is actively solving problems such as spectral interference, mass discrimination drift, chemical separation and purification, and reduction of the contamination of analytes. This article describes data calibration and standardization protocols to allow interlaboratory comparisons or to maintain traceability of data, and basic principles of isotope fractionation in nature, together with high-selectivity and high-yield chemical separation and purification techniques for stable isotope studies.

High-contrast, high-intensity laser pulse generation using a nonlinear preamplifier in a Ti:sapphire laser system

We report a high-contrast, high-intensity Ti:sapphire chirped-pulse amplification system that incorporates a nonlinear preamplifier based on optical parametric chirped-pulse amplification (OPCPA). By cooling the Ti:sapphire crystal in the final amplifier down to 77 K, the chirped-pulses are amplified to 2.9 J at a 10 Hz repetition rate without a thermal lensing effect. Pulse compression down to 19 fs duration obtained after amplification indicates a peak power of 80 TW. With the OPCPA, the temporal contrast is significantly improved to better than 7x10(-9) in a few picoseconds interval prior to the main laser pulse.     

Order-disorder phase transition in a chaotic system

For soft-mode turbulence, which is essentially the spatiotemporal chaos caused by the nonlinear interaction between convective modes and Goldstone modes in electroconvection of homeotropic nematics, a type of order-disorder phase transition was revealed, in which a new order parameter was introduced as pattern ordering. We calculated the spatial correlation function and the anisotropy of the convective patterns as a 2D XY system because the convective wave vector could freely rotate in the homeotropic system. We found the hidden order in the chaotic patterns observed beyond the Lifshitz frequency f(L), and a transition from a disordered to a hidden ordered state occurred at the f(L) with the increase of the frequency of the applied voltages.     

Lewis-Pairing-Induced Electrochemiluminescence Enhancement from Electron Donor-Acceptor Diads Decorated with Tris(pentafluorophenyl)borane as an Electrochemical Protector

This study reports an effective peripheral decoration of organic donor-acceptor diads with B(C₆F₅)₃ for stabilizing electrogenerated radical ions. By employing a common p-type organic semiconductor benzothienobenzothiophene (BTBT) as the donor, tetracoordinate boron complexes showed improved solution electrochemiluminescence (ECL) intensity, reaching a 156-fold increase compared to that of the parent diad. The unprecedented Lewis-pairing-induced ECL enhancement is attributed to the multiple roles of B(C₆F₅)₃: 1) redistributing frontier orbitals, 2) facilitating electrochemical excitation, and 3) restricting molecular motions. Furthermore, B(C₆F₅)₃ converted the molecular arrangement of BTBT from conventional 2D herringbones into 1D π-stacks. This robust, highly ordered columnar nanostructure allowed red-shifting of the crystalline film ECL with electrochemical doping through the electronic coupling pathways of BTBT. Our approach will facilitate the development of elaborate metal-free ECL systems.     

Synthesis of well-defined azido and amino end-functionalized polystyrene by atom transfer radical polymerization

Mono and difunctional polystyrenes containing active halogenated end groups were prepared by atom transfer radical polymerization (ATRP). Substitution reactions were explored to convert the halogen termini to azido groups, followed by readuction to form the amino functional polymer. Quantitative conversion of the end groups was observed in each transformation reaction. ¹H NMR demonstrated the formation of the azide from the bromide functionality without elimination. The difunctional α,ω-diaminopolystyrene was reacted with terephthaloyl chloride in a condensation process to produce chain-extended polystyrene containing amide bonds along the polymer backbone.     

Functional polymers based on high hydrophilicity of poly(2-methyl-2-oxazoline)

Polymers of the family of 2-substituted 2-oxazolines have the general structure of poly(N-acylethylenimine), whose hydrophilic/lipophilic properties vary according to the substituent, i.e., the acyl group of the polymer. Of special interest is the polymer of 2-methyl-substituted monomer, which has a strong affinity for water. Another useful feature of the 2-oxazoline family is the fact that its polymerization reaction is quite clean without disturbance by chain transfer and termination. On the basis of the above characteristics, three kinds of novel materials of functional polymers have been explored:

• 1. Non-ionic polymeric surfactants.
• 2. Non-ionic hydrogels.
• 3. Block copolymer with silica gel: Organic/inorganic polymers hybrids.