72 research outputs found
Defect engineering of polyethylene-like polyphosphoesters: Solid-state NMR characterization and surface chemistry of anisotropic polymer nanoplatelets
Anisotropic materials with very high aspect ratios, such as nanoplatelets, are an exciting class of materials due to their unique properties based on their unilamellar geometry. Controlling their size and surface-functionality is challenging and has only be achieved in some cases for synthetic polymers. We present a general approach to prepare polymer-nanoplatelets with control over the lateral size and basal functionality, by simple polycondensation of precisely spaced and functional phosphate groups in polyethylene-like polymers. Because of the relatively large size of the phosphate groups, they are expelled from the bulk crystal to the basal surface. This allows to control the chain-folding during crystallization, which we analyzed via solid-state NMR and TEM. Furthermore, we present chemistry “on the surface” of the platelets: the pendant ester group at the phosphate offers the possibility to introduce functional groups accessible for further chemical modification on the crystal surface. This is shown by introducing a 2-acetylthioethyl ester group and subsequently cleaving this 2-acetylthioethyl ester group to the free P–OH. Together, these results render polyethylene-like polyphosphoesters a versatile platform for soft-matter nanoplatelets as functional colloids
Copolymerization of Cyclic Phosphonate and Lactide: Synthetic Strategies toward Control of Amphiphilic Microstructure
Controlling
the microstructure of polymers through chemical reactivity
is key to control the material properties of synthetic polymers. Herein
we investigate the ring-opening copolymerization of a mixture of lactide
and 2-ethyl-2-oxo-1,3,2-dioxaphospholane, promoted by an aluminum
pyrrolidine monophenolate complex or 1,8-diazabicyclo[5.4.0]undec-7-ene
(DBU). This monomer mixture provides fast access to amphiphilic copolymers.
The reaction conditions control the copolymer microstructure, which
has been determined via a combination of <sup>1</sup>H and <sup>31</sup>P NMR spectroscopy. The choice of initiator has a profound impact:
both initiators produce tapered block copolymers but with reverse
monomer selectivity. While the aluminum initiator favors the cyclic
phosphonate monomer, DBU favors lactide polymerization. Moreover,
a sequential control of temperature facilitates the preparation of
block copolymers in one pot. Thermal properties measured by TGA and
DSC correlate to copolymer architectures. This methodology is the
first report of copolymerization between cyclic phosphonates and lactide
and opens the possibility to tune the thermal properties, solubility,
and degradation rates of the resulting materials
Pilot Randomized Controlled Trial of IN FOCUS: A Mind‐Body Resiliency Intervention for Fear of Cancer Recurrence
INTRODUCTION: Fear of cancer recurrence (FCR) is prevalent and distressing among survivors of cancer. Evidence-based mind-body and cognitive-behavioral skills lack integration and testing in scalable formats. OBJECTIVE: This pilot randomized controlled trial (NCT04876599) tested a synchronous, virtual mind-body group resiliency intervention for FCR (IN FOCUS). METHOD: Adults with elevated FCR (FCR Inventory severity ≥ 16; 16-21 = elevated, 22-36 = clinically elevated) after completing primary treatment for non-metastatic cancer were randomly assigned (1:1) to eight weekly sessions of IN FOCUS or usual care (UC; synchronous, virtual community group support referral). Feasibility metrics included ≥ 70% retention per arm (primary outcome), ≥ 75% attendance in ≥ 6 sessions, ≥ 75% adherence to relaxation skills practice ≥ 3 days per week and by delivery fidelity (% content covered in video-recorded sessions). Acceptability was assessed quantitatively via ratings of enjoyableness, convenience, helpfulness, odds of future use, and satisfaction (benchmark ≥ 80% of ratings ≥ 4 on 1-5 Likert scale) and qualitatively via individual exit interviews. Linear mixed models explicated slopes in FCR (secondary) and resiliency (exploratory; Current Experiences Scale) from baseline to 2 months (primary endpoint) and 5 months using intention-to-treat. RESULTS: From July 2021 to March 2022, 64 survivors enrolled (25-73 years old, M = 7 years since diagnosis). IN FOCUS was feasible and acceptable (91% retention; attendance median = 7 sessions, 97% relaxation practice adherence, 95% content fully covered; 82% of acceptability ratings ≥ 4). Interviews (n = 59) revealed benefits in both arms. By 2 months, compared to UC, IN FOCUS reduced FCR to a medium-to-large effect (Mdiff = -2.4; 95% CI = -4.2, -0.7; d = 0.66). By 5 months, FCR effects had attenuated (Mdiff = -0.16, 95% CI -1.97, 1.65; d = -0.04), although levels of resiliency had increased with a medium-to-large effect (Mdiff = 10.0; 95% CI = 4.9, 15.1; d = 0.78). CONCLUSIONS: For survivors of non-metastatic cancer, a synchronous, virtual mind-body resiliency program for FCR is feasible, acceptable, and seemingly beneficial compared to a community group referral
Identification of regulatory variants associated with genetic susceptibility to meningococcal disease
Non-coding genetic variants play an important role in driving susceptibility to complex diseases but their characterization remains challenging. Here, we employed a novel approach to interrogate the genetic risk of such polymorphisms in a more systematic way by targeting specific regulatory regions relevant for the phenotype studied. We applied this method to meningococcal disease susceptibility, using the DNA binding pattern of RELA - a NF-kB subunit, master regulator of the response to infection - under bacterial stimuli in nasopharyngeal epithelial cells. We designed a custom panel to cover these RELA binding sites and used it for targeted sequencing in cases and controls. Variant calling and association analysis were performed followed by validation of candidate polymorphisms by genotyping in three independent cohorts. We identified two new polymorphisms, rs4823231 and rs11913168, showing signs of association with meningococcal disease susceptibility. In addition, using our genomic data as well as publicly available resources, we found evidences for these SNPs to have potential regulatory effects on ATXN10 and LIF genes respectively. The variants and related candidate genes are relevant for infectious diseases and may have important contribution for meningococcal disease pathology. Finally, we described a novel genetic association approach that could be applied to other phenotypes
Identification of regulatory variants associated with genetic susceptibility to meningococcal disease.
Non-coding genetic variants play an important role in driving susceptibility to complex diseases but their characterization remains challenging. Here, we employed a novel approach to interrogate the genetic risk of such polymorphisms in a more systematic way by targeting specific regulatory regions relevant for the phenotype studied. We applied this method to meningococcal disease susceptibility, using the DNA binding pattern of RELA - a NF-kB subunit, master regulator of the response to infection - under bacterial stimuli in nasopharyngeal epithelial cells. We designed a custom panel to cover these RELA binding sites and used it for targeted sequencing in cases and controls. Variant calling and association analysis were performed followed by validation of candidate polymorphisms by genotyping in three independent cohorts. We identified two new polymorphisms, rs4823231 and rs11913168, showing signs of association with meningococcal disease susceptibility. In addition, using our genomic data as well as publicly available resources, we found evidences for these SNPs to have potential regulatory effects on ATXN10 and LIF genes respectively. The variants and related candidate genes are relevant for infectious diseases and may have important contribution for meningococcal disease pathology. Finally, we described a novel genetic association approach that could be applied to other phenotypes
The need to reform the YOA in response to violent young offenders: Confusion, reality or myth?
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