Optimization of alkali fusion process for determination of I-129 in solidified radwastes by neutron activation

This study determines the optimum temperature for the alkali fusion process used to effectively separate iodine from solidified radwaste attaining low-level ¹²⁹I by neutron activation. The alkali fusion temperature was adjusted to 120, 200, and 400 °C to approach the optimum conditions associated with a good statistical distribution of the measured ¹²⁹I data and high chemical recovery yield. Statistical analysis revealed that the optimum temperature of the alkali fusion process was 200 °C, displaying good central tendency and low variance of the measured ¹²⁹I data, and the respective chemical recovery yields were higher than other temperatures. The optimum fusion condition provides more reliable scaling factors (¹²⁹I/¹³⁷Cs) of radwaste.

Upregulation of Haploinsufficient Gene Expression in the Brain by Targeting a Long Non-coding RNA Improves Seizure Phenotype in a Model of Dravet Syndrome

Dravet syndrome is a devastating genetic brain disorder caused by heterozygous loss-of-function mutation in the voltage-gated sodium channel gene SCN1A. There are currently no treatments, but the upregulation of SCN1A healthy allele represents an appealing therapeutic strategy. In this study we identified a novel, evolutionary conserved mechanism controlling the expression of SCN1A that is mediated by an antisense non-coding RNA (SCN1ANAT). Using oligonucleotide-based compounds (AntagoNATs) targeting SCN1ANAT we were able to induce specific upregulation of SCN1A both in vitro and in vivo, in the brain of Dravet knock-in mouse model and a non-human primate. AntagoNAT-mediated upregulation of Scn1a in postnatal Dravet mice led to significant improvements in seizure phenotype and excitability of hippocampal interneurons. These results further elucidate the pathophysiology of Dravet syndrome and outline a possible new approach for the treatment of this and other genetic disorders with similar etiology.

Highly efficient drug delivery systems based on functional supramolecular polymers: In vitro evaluation

The novel concept of modifying and enhancing the properties of existing functional micelles through self-complementary interactions has significant potential. In this study, a practical approach to living polymerization of functionalized thermoresponsive monomers enabled the incorporation of self-constituted multiple hydrogen bonded groups into micelles that have potential as supramolecular drug-delivery systems. Phase transitions and morphological studies in aqueous solution showed that the microstructure can be controlled to achieve well-defined vesicle-like micelles with respect to the strength of the hydrogen bond segment. Thus, the resulting micelles have a very low critical micellization concentration and very high loading capacity (16.1%), making the loading process extremely stable and efficient. Incorporation of the anticancer drug doxorubicin (DOX) affected the micellization process in aqueous solution and enabled fine-tuning of drug loading and precise control of drug release rate with excellent sensitivity. Release studies in vitro showed that DOX-loaded micelles exerted dose-dependent cytotoxicity against human liver carcinoma (HepG2) cells at the physiological temperature of 37°C. In addition, DOX-loaded micelles were efficiently endocytosed by the cancer cells, which may enable the micelles to serve as suitable vehicles for effective delivery of anticancer drugs to primary tumors and metastatic disease. This newly developed material may provide a potential route towards next-generation drug delivery vehicles.

STATEMENT OF SIGNIFICANCE

A breakthrough innovation in water-based thermo-responsive polymers has enabled significant progress in developing smart stimuli-responsive nanocarriers by generating novel "supramolecular polymeric micelles" via self-complementary hydrogen-bonding interactions. These newly developed micelles exhibit extremely high micellar stability and drug loading capacity (up to 16%), excellent thermo-responsive behavior and precise control of drug release rate due to hydrogen-bond-induced physical cross-linking. In addition, doxorubicin-loaded micelles were efficiently endocytosed by the cancer cells, which allows them to serve as suitable vehicles for effective delivery of anticancer drugs to primary tumors and metastatic disease. Thus, this work provides a potential route for the development of next generation multifunctional nanocarriers that have improved safety and to increase the therapeutic efficacy of anticancer therapy.

Functionalized graphene nanomaterials: new insight into direct exfoliation of graphite with supramolecular polymers

A novel urea-cytosine end-capped polypropylene glycol (UrCy-PPG) can self-assemble into a long-range ordered lamellar microstructure on the surface of graphene, due to the strong specific interactions between UrCy-PPG and graphene. In addition, the graphene composite produced exhibits a high conductivity (∼1093 S m(-1)) with a dramatic thermo-responsive ON/OFF resistance-switching behavior (10 consecutive cycles).

Supramolecular Assembly Mediates the Formation of Single-Chain Polymeric Nanoparticles

A breakthrough innovation in water-based polymeric nanoparticles has enabled significant progress in mimicking the folding of natural proteins by generating novel "single-chain polymeric nanoparticles" (SCPNs) via supramolecular interactions. In this study, a practical approach to the living polymerization of functionalized oligo(ethylene glycol) methacrylate monomers allows the incorporation of self-constituted multiple hydrogen-bonded groups into physically cross-linked polymer networks, which enables the formation of highly functionalized SCPNs in an aqueous environment. The newly developed materials are particularly attractive from a practical point of view since they have a very low critical micellization concentration and uniform particle diameters of ca. 25 nm, making them extremely stable under dilute conditions. Concentration-dependent experiments showed that SCPNs formed at polymer concentrations up to 40 mg/mL with no significant change in morphology observed. Moreover, the formed SCPNs had a very high stability in an aqueous solution containing surfactant, suggesting potential for a wide variety of applications as a promising candidate nanocarrier for bioimaging, controlled release, and drug delivery systems.

Supramolecular assembly-induced enhanced emission of electrospun nanofibers

A nucleobase-assembled supramolecular nanofiber is capable of forming network-like polymeric clusters through complementary hydrogen-bonding interactions. It behaves as an effective chromophore that greatly enhances the light emission efficiency of fluorescent fibers, reaching up to three times higher efficiency than the control samples.

Bio-complementary supramolecular polymers with effective self-healing functionality

Self-healing supramolecular polymers can be rapidly reprocessed under mild temperature conditions via dynamic reshuffling of the hydrogen bond networks.

A cross-linkable triphenylamine derivative as a hole injection/transporting material in organic light-emitting diodes

A new thermally cross-linkable triphenylamine derivative containing a benzoxazine functional group for application in organic light-emitting diodes (OLEDs.)

High-efficiency self-healing materials based on supramolecular polymer networks

A new urea–cytosine-functionalized supramolecular polymer can be rapidly reshaped and reprocessed under mild conditions via rearrangement of the hydrogen bonding network.

Large-scale production of ureido-cytosine based supramolecular polymers with well-controlled hierarchical nanostructures

A novel UrCy–PPG was developed for the synthesis of high-quality supramolecular polymers in large-scale production utilizing only commercially-available chemicals.

Polystyrene foams with inter-connected carbon particulate network

New polystyrene (PS)/carbon nanofiber (CNF) and PS/graphite foams with an inter-connected honeycomb-like carbon particulate network of CNF or graphite were prepared by first coating the surface of polymer pellets with either CNF or graphite and then conducting batch foaming using carbon dioxide (CO2) as a blowing agent. It was found that the inter-connected honeycomb-like carbon particulate network could significantly reduce the compression yielding of conventional PS foams. With 1 wt% of CNFs or graphite, the PS foams with inter-connected honeycomb-like carbon particulate network were 5–9 times more electrically conductive than foams made of compounded PS nanocomposite with the same carbon particle loading. In addition, the PS foams with inter-connected honeycomb-like carbon particulate network were more thermally conductive and revealed significantly improved thermal stability comparing to foams made of compounded polymer nanocomposites.

Synthesis and self-assembly of water-soluble polythiophene-graft-poly(ethylene oxide) copolymers

Poly(3-hexylthiophene)-graft-poly(ethylene oxide) (P3HT-g-PEO) rod–coil conjugated random copolymers through oxidative polymerization with FeCl₃ and facile click chemistry.

Mercury wet deposition in the eastern United States: characteristics and scavenging ratios

Wet deposition is an important atmospheric mercury (Hg) pathway between air and terrestrial ecosystems. It is measured at numerous locations in the United States (U. S.) as part of the Mercury Deposition Network (MDN). The annual Hg wet deposition flux in 2009 at four locations in the northeastern U. S. (MDN sites MD08, VT99, NY20, and NY43) ranged from 6.4 to 13.4 μg per m(2) year which is higher than modeled reactive Hg (RM) dry deposition for this region. The highest ambient RM concentrations were seen at MD08, which is closest to significant anthropogenic sources; however, the volume-weighted mean Hg concentrations in precipitation were similar at these four sites. Mass based scavenging ratios (SC) of RM ranged from 1700 to 4500. Differences in SCs were likely a result of differences in meteorological conditions, the forms of RM in the atmosphere, vertical concentration variations, and measurement uncertainties, including precipitation depth and RM concentrations. RM SCs were higher than those reported for other soluble species. Multiple linear regression suggests that gaseous oxidized Hg is responsible for the majority of the scavenged RM.

Bioinspired assembly of functional block-copolymer nanotemplates

A new concept on bioinspired assembly of functional diblock copolymers, capable of forming different microstructures through nucleobase-induced supramolecular interactions, has been explored. In this paper, a new series of uracil-functionalized poly(ε-caprolactone)-b-(4-vinylbenzyl uracil)s (PCL-b-PVBU) have been prepared which exhibit a high self-complementary ability in solution and solid states owing to the formation of uracil–uracil pairs by induced hierarchical self-assembly. The ordered morphologies of PCL-b-PVBU diblock copolymers changed from a lamellar, hexagonally packed cylinder to a sphere with respect to the content of the hydrogen bond segment. Moreover, we further show that the PCL segment could be easily extracted by enzymatic degradation, leading to a cylinder porous structure of long-range order, which gives a facile method for the fabrication of uracil-functionalized nanotemplates. In addition, bio-complementary PCL-b-PVBU/9-hexadecyladenine (AC16) hierarchical supramolecular complexes formed through strong cooperative hydrogen bonding between the uracil group of PVBU and the adenine group of A-C16. When the mixing ratios of PCL-b-PVBU/AC16 differ from the stoichiometric ratio, these complexes self-assemble into well-ordered lamellar and hexagonal structures; the changing morphology at different AC16 loadings reveals that the molecular structures of the PCL-b-PVBU/AC16 complexes are readily tailored.

Can iterative reconstruction improve imaging quality for lower radiation CT perfusion? Initial experience

BACKGROUND AND PURPOSE

Initial results using IR for CT of the head showed satisfactory subjective and objective imaging quality with a 20-40% radiation dose reduction. The aim of our study was to compare the influence of IR and FBP algorithms on perfusion parameters at standard and lowered doses of CTP.

MATERIALS AND METHODS

Forty patients with unilateral carotid stenosis post-carotid stent placement referred for follow-up CTP were divided into 2 groups (tube currents were 100 mAs in group A and 80 mAs in group B). Datasets were reconstructed with IR and FBP algorithms; and SNRs of gray matter, white matter, and arterial and venous ROIs were compared. CBF, CBV, and MTT means and SNRs were evaluated by using linear regression, and qualitative imaging scores were compared across the 2 algorithms.

RESULTS

The mean effective radiation dose of group B (2.06 mSv) was approximately 20% lower than that of group A (2.56 mSv). SNRs for ROIs in the dynamic contrast-enhanced images were significantly higher than those for the FBP images. Correlations of the SNRs for CBF, CBV, and MTT across the 2 algorithms were moderate (R² = 0.46, 0.23, and 0.44, respectively). ROIs in gray matter rather than the IR algorithm predicted increasing SNRs in all CBF, CBV, and MTT maps. Two cases of significant restenosis were confirmed in both algorithms. CBV, CBF, and MTT imaging scores did not differ significantly across algorithms or groups.

CONCLUSIONS

Lower dose CTP (20% below normal dose) without IR can effectively identify oligemic tissue in poststenting follow-up. IR does not alter the absolute values or increase the SNRs of perfusion parameters. Other methods should be attempted to improve SNRs in settings with low tube currents.

Electrorheological operation of low-/high-permittivity core/shell SiO2/Au nanoparticle microspheres for display media

In this study, we synthesized core/shell structures comprising monodisperse 3-μm SiO(2) microspheres and gold nanoparticles (AuNPs, ca. 6.7 nm) as the core and shell components, respectively. Using a layer-by-layer cross-linking process with a dithiol cross-linking agent, we prepared low-permittivity AuNP-encapsulated high-permittivity SiO(2) core/shell microspheres with variable AuNP shell thicknesses. The dispersivity of the microspheres in solution was enhanced after grafting poly(ethylene glycol) monomethyl ether thiol (PEG-SH) onto the AuNP layer on the SiO(2) microspheres. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) images revealed sesame ball-like structures for these SiO(2)@AuNP@PEG microspheres. We encapsulated aqueous dispersions of these SiO(2)@AuNP microspheres into sandwich structured displays (SSDs) to investigate their electrorheological properties, observing reversibly electroresponsive transmittance that is ideally suited for display applications. Increasing the thickness of the AuNP layer dramatically enhanced the stringing behavior of the SiO(2) microspheres, resulting in increased transmittance of the SSD. The response time of the electroresponsive electrorheological fluids also decreased significantly after modifying the SiO(2) with the AuNP layers. The effective permittivities of these composites could be predicted from the real (έ) and imaginary (έ́) parts of the Clausius-Mossotti formalism.