Well-defined hyperstar copolymers based on a thiol–yne hyperbranched core and a poly(2-oxazoline) shell for biomedical applications

Well defined ‘hyperstar’ copolymers were synthesized by combining hyperbranched polymers produced by thiol–yne chemistry with poly(oxazoline)s. The hyperbranched core was prepared using an AB2 monomer and a trifunctional alkene, applying a monomer feeding approach. The degree of branching was high (0.9) while maintaining low dispersities (1.3). Poly(2-ethyl-2-oxazoline) (PEtOx) functionalized with a thiol end group was coupled to the surface of the hyperbranched structure accessing terminal alkyne units. PEtOx-SH was produced by the termination of the living polymerization with ethyl xanthate and subsequent conversion to thiol under alkaline conditions. The degree of polymerization was varied producing PEtOx with 23 or 42 repeating units, respectively with a dispersity of around 1.1. After conjugation of the polymer arms, hyperstar copolymers were characterized by SEC, NMR spectroscopy, light scattering, and AFM. The polymers were able to encapsulate the hydrophobic dye Nile red within the core of the structure with loading efficiencies between 0.3 and 0.9 wt%. Cytotoxicity of the hyperstars was assessed using A2780 human ovarian carcinoma cells resulting in IC50 values of around 0.7 mg ml−1. Successful internalization and colocalization with lysosomal compartments was observed by confocal microscopy studies

Advanced Patient-Centered Communication for Health Behavior Change: Motivational Interviewing Workshops for Medical Learners

Introduction: Medical settings are critical access points for behavior change counseling, and lifestyle behavior change is considered a key component of chronic disease management. The Association of American Medical Colleges recommends that future physicians be competent in shared decision making and patient-centered behavioral guidance to prevent illness and improve patient self-management of chronic disease. Motivational interviewing (MI) is a patient-centered, directive method of communication to enhance behavior change. Specific teachable strategies underlie the collaborative MI communication style that aims to reduce discord and build motivation for change. Methods: We present our three-session 12-hour MI curriculum as an advanced form of patient-centered communication. Each session includes presession assignment, large-group interactive lecture, and small-group activities for practice. An interdisciplinary team consisting of medical educators and health behavior change research-educators who are also members of the Motivational Interviewing Network of Trainers created the submission. The purpose of this resource is to provide medical educators with a short curriculum that incorporates materials and learning activities to promote skill in MI. Results: In addition to positive feedback from student evaluations including the areas of relevance to training and self-rated skills improvement, preliminary pre- and posttraining scores from the medical students show significant improvement in expression of empathy and the ratio of reflections to questions. Discussion: Implementation of the curriculum allows learners the opportunity to practice evidence-based communication that promotes intrinsic motivation for health behavior change in patients, a key treatment focus in chronic disease management

Recruitment Strategies and the Retention of Obese Urban Racial/Ethnic Minority Adolescents in Clinical Trials: The FIT Families Project, Michigan, 2010–2014

Introduction The successful recruitment and retention of participants is integral to the translation of research findings. We examined the recruitment and retention rates of racial/ethnic minority adolescents at a center involved in the National Institutes of Health Obesity Research for Behavioral Intervention Trials (ORBIT) initiative by the 3 recruitment strategies used: clinic, informatics, and community. Methods During the 9-month study, 186 family dyads, each composed of an obese African American adolescent and a caregiver, enrolled in a 6-month weight-loss intervention, a sequential multiple assignment randomized trial. We compared recruitment and retention rates by recruitment strategy and examined whether recruitment strategy was related to dyad baseline characteristics. Results Of the 186 enrolled families, 110 (59.1%) were recruited through clinics, 53 (28.5%) through informatics, and 23 (12.4%) through community. Of those recruited through community, 40.4% enrolled in the study, compared with 32.7% through clinics and 8.2% through informatics. Active refusal rate was 3%. Of the 1,036 families identified for the study, 402 passively refused to participate: 290 (45.1%) identified through informatics, 17 (29.8%) through community, and 95 (28.3%) through clinics. Recruitment strategy was not related to the age of the adolescent, adolescent comorbidities, body mass index of the adolescent or caregiver, income or education of the caregiver, or retention rates at 3 months, 7 months, or 9 months. Study retention rate was 87.8%. Conclusion Using multiple recruitment strategies is beneficial when working with racial/ethnic minority adolescents, and each strategy can yield good retention. Research affiliated with health care systems would benefit from the continued specification, refinement, and dissemination of these strategies

An Exercise in Visualizing Colexification on a Semantic Map

This paper aims at investigating the polysemic patterns associated with the notion ‘soil/earth’ by using the semantic map model as a methodological tool. We focus on the applicability of the model to the lexicon, since most of past research has been devoted to the analysis of grammatical morphemes. The most concise result of our research is a diagrammatic visualization of the semantic spaces of twenty lexemes in nine different languages, mainly ancient languages belonging to the Indo-European and the Afro-Asiatic language families. The common semantic map for the various languages reveals that the semantic spaces covered by the investigated lexemes are often quite different from one another, although common patterns can also be detected. Our study highlights some shortcomings and methodological problems of previous analyses suggesting that a possible solution to these problems is the control of the data in the existing sources of the object languages. Finally, drawing upon the cognitive linguistics literature on the various types of semantic change, we show that some of the senses of the individual lexemes are the result of the function of such mechanisms as metaphor, metonymy, and generalization

Unusually strong space-charge-limited current in thin wires

The current-voltage characteristics of thin wires are often observed to be nonlinear, and this behavior has been ascribed to Schottky barriers at the contacts. We present electronic transport measurements on GaN nanorods and demonstrate that the nonlinear behavior originates instead from space-charge-limited current. A theory of space-charge-limited current in thin wires corroborates the experiments, and shows that poor screening in high aspect ratio materials leads to a dramatic enhancement of space-charge limited current, resulting in new scaling in terms of the aspect ratio.Comment: 4 pages, 3 figures, to appear in Physical Review Letter

Dual self-assembly of supramolecular peptide nanotubes to provide stabilisation in water

Self-assembling peptides have the ability to spontaneously aggregate into large ordered structures. The reversibility of the peptide hydrogen bonded supramolecular assembly make them tunable to a host of different applications, although it leaves them highly dynamic and prone to disassembly at the low concentration needed for biological applications. Here we demonstrate that a secondary hydrophobic interaction, near the peptide core, can stabilise the highly dynamic peptide bonds, without losing the vital solubility of the systems in aqueous conditions. This hierarchical self-assembly process can be used to stabilise a range of different β-sheet hydrogen bonded architectures

High-resolution dielectric characterization of minerals: a step towards understanding the basic interactions between microwaves and rocks

Microwave energy was demonstrated to be potentially beneficial for reducing the cost of several steps of the mining process. Significant literature was developed about this topic but few studies are focused on understanding the interaction between microwaves and minerals at a fundamental level in order to elucidate the underlying physical processes that control the observed phenomena. This is ascribed to the complexity of such phenomena, related to chemical and physical transformations, where electrical, thermal and mechanical forces play concurrent roles. In this work a new characterization method for the dielectric properties of mineral samples at microwave frequencies is presented. The method is based upon the scanning microwave microscopy technique that enables measurement of the dielectric constant, loss factor and conductivity with extremely high spatial resolution and accuracy. As opposed to conventional dielectric techniques, the scanning microwave microscope can then access and measure the dielectric properties of micrometric-sized mineral inclusions within a complex structure of natural rock. In this work two micrometric hematite inclusions were characterized at a microwave frequency of 3 GHz. Scanning electron microscopy/energy-dispersive x-ray spectroscopy and confocal micro-Raman spectroscopy were used to determine the structural details and chemical and elemental composition of mineral sample on similar scale

Intramolecular Energy and Electron Transfer Within a Diazaperopyrenium-Based Cyclophane

Molecules capable of performing highly efficient energy transfer and ultrafast photo-induced electron transfer in well-defined multichromophoric structures are indispensable to the development of artificial photosynthetic systems. Herein, we report on the synthesis, characterization and photophysical properties of a rationally designed multichromophoric tetracationic cyclophane, DAPPBox^(4+), containing a diazaperopyrenium (DAPP^(2+)) unit and an extended viologen (ExBIPY^(2+)) unit, which are linked together by two p-xylylene bridges. Both ^1H NMR spectroscopy and single crystal X-ray diffraction analysis confirm the formation of an asymmetric, rigid, box-like cyclophane, DAPPBox^(4+). The solid-state superstructure of this cyclophane reveals a herringbone-type packing motif, leading to two types of π···π interactions: (i) between the ExBIPY^(2+) unit and the DAPP^(2+) unit (π···π distance of 3.7 Å) in the adjacent parallel cyclophane, as well as (ii) between the ExBIPY^(2+) unit (π···π distance of 3.2 Å) and phenylene ring in the closest orthogonal cyclophane. Moreover, the solution-phase photophysical properties of this cyclophane have been investigated by both steady-state and time-resolved absorption and emission spectroscopies. Upon photoexcitation of DAPPBox^(4+) at 330 nm, rapid and quantitative intramolecular energy transfer occurs from the ^1*ExBIPY^(2+) unit to the DAPP^(2+) unit in 0.5 ps to yield ^1*DAPP^(2+). The same excitation wavelength simultaneously populates a higher excited state of ^1*DAPP^(2+) which then undergoes ultrafast intramolecular electron transfer from ^1*DAPP^(2+) to ExBIPY^(2+) to yield the DAPP^(3+•) – ExBIPY^(+•) radical ion pair in τ = 1.5 ps. Selective excitation of DAPP^(2+) at 505 nm populates a lower excited state where electron transfer is kinetically unfavorable