Hyperbranched polyethylenimines as versatile precursors for the preparation of different type of unimolecular micelles

2007

Abstract Hyperbranched polyethylenimine (HPEI) was successfully employed as precursor for the preparation of unimolecular inverted and aqueous micelles. The unimolecular inverted micelles (UIMs) obtained by the amidation of HPEI with 1,1′-carbonyldiimidazole (CDI) activated palmitic acid exhibited high encapsulation efficiency for hydrophilic anionic dyes and the efficiency could be enhanced significantly by decreasing the degree of amidation or quaternizing the residual amines. The weight ratio of loaded guests to the amidated HPEIs was not dependent on the molecular weight of HPEI core when the degree of amidation was kept constant. Decreasing the length of the aliphatic chain from 16 to …

Thermoresponsive hyperbranched polyethylenimines with isobutyramide functional groups

2007

Core–shell-type multiarm star polyethylenimine-block-poly(ɛ-caprolactone): Synthesis and guest encapsulation potential

2006

Novel multiarm star copolymers with poly(e-caprolactone) (PCL) as the arms and hyperbranched polyethylenimine (HPEI) as the core have been successfully prepared by the tin(II) 2-ethylhexanoate catalyzed ring-opening polymerization of e-caprolactone (CL) with HPEI used directly as a macroinitiator. Not only primary but also secondary amine groups of HPEI participate in initiating the ring-opening polymerization of CL with almost 100% initiation efficiency. The average degree of polymerization of the PCL arms can be controlled by the feed ratio of the monomers to the initiating sites. Because of the polarity difference of the PCL arms and HPEI core, the obtained multiarm star polymers display…

Calibration strategy of the JUNO experiment

2021

We present the calibration strategy for the 20 kton liquid scintillator central detector of the Jiangmen Underground Neutrino Observatory (JUNO). By utilizing a comprehensive multiple-source and multiple-positional calibration program, in combination with a novel dual calorimetry technique exploiting two independent photosensors and readout systems, we demonstrate that the JUNO central detector can achieve a better than 1% energy linearity and a 3% effective energy resolution, required by the neutrino mass ordering determination. [Figure not available: see fulltext.]

Synergistic assembly of hyperbranched polyethylenimine and fatty acids leading to unusual supramolecular nanocapsules

2005

Self-assembly of hyperbranched polyethylenimine (PEI) and fatty acids leads to supramolecular inverted micellar structures that are able to irreversibly transfer water-soluble guest molecules into organic solvents. Perez Prieto, Julia, Julia.Perez@uv.es ; Stiriba, Salah Eddine, Salah.Stiriba@uv.es

Equilibrium swelling and solvation studies on crosslinked polyacrylamides

2004

Polyacrylamide (PA) crosslinked with four different crosslinking agents, triethyleneglycol dimethacrylate (TEGDMA), N,N′-methylene bisacrylamide (NNMBA), hexanediol dimethacrylate (HDDMA) and divinylbenzene (DVB), with mole percents ranging from 5 to 20, was prepared by solution polymerization and subjected to swelling and solvation studies. Solubility parameters and cohesive energy density were determined from swelling studies. Molecular weight between crosslinks for these systems were determined by Flory–Rehner analysis. There is a discontinuous volume change for 10% NNMBA and HDDMA crosslinked PA, 15% TEGDMA crosslinked PA and 10 and 15% DVB crosslinked PA in solvent mixtures of acetic a…

Multi-Arm Star Polyglycerol-block-poly(tert-butyl acrylate) and the Respective Multi-Arm Poly(acrylic acid) Stars

2006

Well-defined multi-arm star block copolymers, polyglycerol-block-poly(tert-butyl acrylate) (PG-b-PtBA), with average arm-numbers of 17, 27, 36, 66 and 90 arms, respectively, have been prepared by atom transfer radical polymerization (ATRP) of tBA in acetone, using a core-first strategy. After hydrolysis with excess concentrated HCl in refluxing dioxane, full hydrolysis of the tert-butyl ester groups was achieved, resulting in multi-arm star polyelectrolytes, polyglycerol-block-poly(acrylic acid) (PG-b-PAA). The hyperbranched macroinitiators employed were prepared on the basis of hyperbranched polyglycerols via esterification with 2-bromoisobutyryl bromide. Both CuBr/PMDETA and CuBr/Me 6 TRE…

Optically active amphiphilic hyperbranched polyglycerols as templates for palladium nanoparticles

2006

Abstract We report a systematic study on the encapsulation of palladium nanoparticles in optically active amphiphilic hyperbranched polyglycerols with different optical signs and different degrees of polymerization, namely (−)-P(G 40 C16 0.5 ) 1 and (+)-P(G 73 C16 0.5 ) 2 . Several issues have been addressed here: (a) relatively wide size distributions (1–5 nm) of palladium nanoparticles have been achieved, (b) a remarkable template effect ( 1 , DP n  = 40, 1.2 ± 0.1 nm; 2 , DP n  = 73, 2.3 ± 0.1 nm average particle size) has been observed using TEM technique, as shown by the particle size dependent on the degree of polymerization of the polymers, (c) NaBH 4 is found to be a convenient redu…

Monoester copillar[5]arenes: synthesis, unusual self-inclusion behavior, and molecular recognition.

2012

The self-inclusion behavior of monoester copillar[5]arenes depends on the position of the ester group, which causes different guest selectivities. Monoester copillar[5]arenes bearing an acetate chain can form stable self-inclusion complexes in low- and high-concentration solution and exhibit high guest selectivity. However, a monoester copillar[5]arene bearing a butyrate chain can not form a self-inclusion complex and exhibits low guest selectivity. Thus, a new class of stable self-inclusion complexes of copillar[5]arenes was explored to improve the selectivity of molecular recognition.

Complexation Selectivities of Pillar[5]arenes with Primary Ammonium Salts

2013

The complexation of alkyl-substituted pillar[5]arenes with primary ammonium salts is investigated. 1,4-Bis(methoxy)pillar[5]arene (MeP5) can form strong complexes with the primary ammonium salts in CDCl3. However, 1,4-bis(ethoxy)pillar[5]arene (EtP5) shows weak interaction with these guests, and 1,4-bis(butoxy)pillar[5]arene (BuP5) can not form such a complex at all. These results indicate that the modified alkyl chains of pillar[5]arene play an important role in the complexation selectivity.

Radioactivity control strategy for the JUNO detector

2021

JUNO is a massive liquid scintillator detector with a primary scientific goal of determining the neutrino mass ordering by studying the oscillated anti-neutrino flux coming from two nuclear power plants at 53 km distance. The expected signal anti-neutrino interaction rate is only 60 counts per day, therefore a careful control of the background sources due to radioactivity is critical. In particular, natural radioactivity present in all materials and in the environment represents a serious issue that could impair the sensitivity of the experiment if appropriate countermeasures were not foreseen. In this paper we discuss the background reduction strategies undertaken by the JUNO collaboration…

Role of Topology and Amphiphilicity for Guest Encapsulation in Functionalized Hyperbranched Poly(ethylenimine)s

2004

The promising potential of dendrimers in a variety of areas, such as catalysis, materials science and biomedicine is related to their globular shape, large number of modifiable surface functionalities and the presence of internal reservoirs.1 Their use in liquidliquid-phase transfer protocols, based on the encapsulation of guest molecules as drug delivery vehicles for pharmaceutical application, represents an important issue.2 Unfortunately, dendrimer synthesis is timeconsuming, which currently limits practical use to laboratory scale. For that reason, hyperbranched polymers prepared from ABm-type monomers in one-step processes have gained increasing interest.3 The development of the slow m…

Multiarm star polyglycerol-block-poly(HEMA) as a versatile precursor for the preparation of micellar nanocapsules with different properties

2007

Well-defined multiarm star polymer with hyperbranched polyglycerol as core and poly(2-hydroxyethyl methacrylate) (PHEMA) as arms were used as precursor for the preparation of inverted and aqueous micellar nanocapsules. The partial modification of the hydroxyl groups of PHEMA arms with aliphatic chains led to the formation of inverted micellar nanocapsules. The hydrophilic dye encapsulation capacity of the inverted micelles can be enhanced significantly by transforming the inner hydroxyl groups of PHEMA arms into quaternized amine groups. The modification of the outer and inner hydroxyl groups of PHEMA arms with polyethylene glycol acid chloride and pivaloyl chloride, respectively, resulted …

A Sequential Algorithm Combining ADAPT and Liver Stiffness Can Stage Metabolic-Associated Fatty Liver Disease in Hospital-Based and Primary Care Pati…

2020

INTRODUCTION Metabolic-associated fatty liver disease is common, with fibrosis the major determinant of adverse outcomes. Population-based screening tools with high diagnostic accuracy for the staging of fibrosis are lacking. METHODS Three independent cohorts, 2 with both liver biopsy and liver stiffness measurements (LSMs, n = 254 and 65) and a population sample (n = 713), were studied. The performance of a recently developed noninvasive algorithm (ADAPT [age, diabetes, PRO-C3 and platelets panel]) as well as aspartate aminotransferase-to-platelet ratio index, fibrosis-4, nonalcoholic fatty liver disease fibrosis score, and LSM was used to stage patients for significant (≥F2) and advanced …

Hnf4α is a key gene that can generate columnar metaplasia in oesophageal epithelium

2017

AbstractBarrett's metaplasia is the only known morphological precursor to oesophageal adenocarcinoma and is characterized by replacement of stratified squamous epithelium by columnar epithelium. The cell of origin is uncertain and the molecular mechanisms responsible for the change in cellular phenotype are poorly understood. We therefore explored the role of two transcription factors, Cdx2 and HNF4α in the conversion using primary organ cultures. Biopsy samples from cases of human Barrett's metaplasia were analysed for the presence of CDX2 and HNF4α. A new organ culture system for adult murine oesophagus is described. Using this, Cdx2 and HNF4α were ectopically expressed by adenoviral infe…

Synthesis of pillar[7]arene

2012

Abstract The first synthesis of pillar[7]arene is reported with two methods. Method A: the FeCl 3 -catalyzed condensation reaction of 1,4-dimethoxybenzene ( 1 ) with paraformaldehyde in CHCl 3 gave dimethoxypillar[7]arene ( 3 ). Method B: the p -toluenesulfonic acid catalyzed condensation reaction of 2,5-bis(benzyloxymethyl)-1,4-dimethoxybenzene ( 2 ) in CH 2 Cl 2 gave compound 3 . Demethylation of 3 with BBr 3 gave pillar[7]arene ( 4 ). The pillar[7]arene might be a perspective macrocyclic host in host–guest chemistry.

Novel Multifunctional Polymeric Photoinitiators and Photo-Coinitiators Derived from Hyperbranched Polyglycerol

2007

A new class of hyperbranched PPIs and PPCs have been prepared. The introduction of compatibilizing groups such as MEEA or trimethylacetate enhanced their solubility in radiation-curable formulations and led to an improved photoactivity compared with the corresponding MPI and MPC. Although the molecular weights of the subject PPIs and PPCs exceeded 800 g mol -1 , the viscosities of the radiation-curable formulations were still suitable for inkjet application. The combination of high photoactivity, low viscosity, and low extract-ability after curing rendered the resulting hyperbranched PPIs and PPCs attractive as components in the inkjet ink for inkjet printing, e.g., in food packaging.

Supramolecular Thermotropic Liquid Crystalline Materials with Nematic Mesophase Based on Methylated Hyperbranched Polyethylenimine and Mesogenic Carb…

2006

Supramolecular interaction of fully methylated hyperbranched polyethylenimines (PEI) with a mesogen-based carboxylic acid, 5-(p-cyanobiphenoxy)pentanoic acid, results in the formation of supramolecular complexes exhibiting thermotropic liquid crystalline (LC) mesophases. In contrast to the common smectic mesophases of most dendritic LC polymers, nematic LC phase were observed. The complexation of PEI and the mesogen units is due to electrostatic interaction between the carboxylate groups and the ammonium end groups of PEI. LC properties were investigated by a combination of differential scanning calorimetry, polarizing light optical microscopy, and X-ray diffractometry.

A monophosphoryl copillar[5]arene: synthesis and host–guest complexation with alkanols

2013

A monophosphoryl copillar[5]arene 1 was prepared. The introduction of the phosphoryl group remarkably promoted the binding affinity of 1 with alkanols and alkanediols in comparison with 1,4-dimethoxypillar[5]arene. Thus 1 can form a stable 1 : 1 host–guest complex with alkanols in CDCl3.

Novel multifunctional hyperbranched polymeric photoinitiators with built-in amine coinitiators for UV curing

2007

A new class of hyperbranched polymeric photoinitiators with built-in amine coinitiators has been developed, showing high functionality, low viscosity, good compatibility with the usual radiation curable formulations, high photoactivity and low extractability from the cured sample.

Synthesis of multiarm star poly(glycerol)-block-poly(2-hydroxyethyl methacrylate).

2006

Well-defined multiarm star block copolymers poly(glycerol)-b-poly(2-hydroxyethyl methacrylate) (PG-b-PHEMA) with an average of 56, 66, and 90 PHEMA arms, respectively, have been prepared by atom transfer radical polymerization (ATRP) of HEMA in methanol by a core-first strategy. The hyperbranched macroinitiators employed were prepared on the basis of well-defined hyperbranched polyglycerol by esterification with 2-bromoisobutyryl bromide. Polydispersites M(w)/M(n) of the new multiarm stars were in the range of 1.11-1.82. Unexpectedly, with the combination of CuCl/CuBr(2)/2,2'-bipyridyl as catalyst, the polymerization conversion can be driven to maximum values of 79%. The control of CuCl cat…

Unprecedented blue intrinsic photoluminescence from hyperbranched and linear polyethylenimines: Polymer architectures and pH-effects

2007

The intrinsic photoluminescence properties of hyperbranched polyethylenimines (PEIs) and their linear counterpart (LPEIs) have been studied in absence of any classical fluorescent probes. The comparison of the inherent fluorescence emission between hyperbranched polyethylenimines and their linear analogues demonstrates that linear polyamines are capable of producing strong intrinsic photoluminescence species having long excited lifetimes without need of having a tridimensional-branched structure. The creation of inherently fluorescent polymeric centers from hyperbranched and linear polyethyleimines can be modulated by specific chemical modification and oxidation of amine groups as well as b…

The Design and Sensitivity of JUNO's scintillator radiopurity pre-detector OSIRIS

2021

The European physical journal / C 81(11), 973 (2021). doi:10.1140/epjc/s10052-021-09544-4

JUNO sensitivity to low energy atmospheric neutrino spectra

2021

Atmospheric neutrinos are one of the most relevant natural neutrino sources that can be exploited to infer properties about cosmic rays and neutrino oscillations. The Jiangmen Underground Neutrino Observatory (JUNO) experiment, a 20 kton liquid scintillator detector with excellent energy resolution is currently under construction in China. JUNO will be able to detect several atmospheric neutrinos per day given the large volume. A study on the JUNO detection and reconstruction capabilities of atmospheric $\nu_e$ and $\nu_\mu$ fluxes is presented in this paper. In this study, a sample of atmospheric neutrino Monte Carlo events has been generated, starting from theoretical models, and then pro…

CCDC 902683: Experimental Crystal Structure Determination

2013

Related Article: Yu Chen, Derong Cao, Lingyun Wang, Minqing He, Lixia Zhou, Dieter Schollmeyer, Herbert Meier|2013|Chem.-Eur.J.|19|7064|doi:10.1002/chem.201204628