Bone Density as a Marker of Response to Radiotherapy in Bone Metastatic Lesions: A Review of the Published Data

Metastases to the bone are presenting in a great percentage of patients with cancer, causing a variety of symptoms, affecting the quality of life and survival of patients. A multidisciplinary approach from different health providers is required for treatment, including radiation oncologists, medical oncologists and surgeons. The role of radiotherapy in the management of bone metastases has long been established through multiple randomized trials. The estimation of response to the therapy is subjective and is based on the palliation of the symptoms that the patients report. However, a quantification of the tumor burden and response to the treatment with the use of an objective method to measure those parameters is a clinical expectation in oncology. The change in bone density in affected areas (mainly lytic) after local radiotherapy, representing the cellular changes that have occurred, is a promising marker of response to treatment.     

Ultimately Sensitive Organic Bioelectronic Transistor Sensors by Materials and Device Structure Design

Organic bioelectronic sensors are gaining momentum as they can combine high‐performance sensing level with flexible large‐area processable materials. This opens to potentially highly powerful sensing systems for point‐of‐care health monitoring and diagnostics at low cost. Prominent to detect biochemical recognition events, are electrolyte‐gated organic field‐effect transistors (EGOFETs) and organic electrochemical transistors (OECTs) as they are easily fabricated and operated. EGOFETs are recently shown to be capable of label‐free single‐molecule detections, even in serum. This progress report aims to provide a critical perspective through a selected overview of the literature on both EGOFET and OECT biosensors. Attention is paid to correctly attribute them to the potentiometric and amperometric biosensor categories, which is important to set the right conditions for quantification purposes. Moreover, to deepen the understanding of the sensing mechanisms, with the support of unpublished data, focus is put on two among the most critical aspects, namely, the capacitance interplay and the role of Faradaic currents. The final aim is to provide a rationale of the functional mechanisms encompassing both EGOFET and OECT sensors, to improve materials and devices' designs taking advantage of the processes that enhance the sensing response enabling the extremely high‐performance level resulting in ultimate sensitivity, selectivity, and fast response.     

The Longest Path Problem Is Polynomial on Cocomparability Graphs

The longest path problem is the problem of finding a path of maximum length in a graph. As a generalization of the Hamiltonian path problem, it is NP-complete on general graphs and, in fact, on every class of graphs that the Hamiltonian path problem is NP-complete. Polynomial solutions for the longest path problem have recently been proposed for weighted trees, Ptolemaic graphs, bipartite permutation graphs, interval graphs, and some small classes of graphs. Although the Hamiltonian path problem on cocomparability graphs was proved to be polynomial almost two decades ago, the complexity status of the longest path problem on cocomparability graphs has remained open; actually, the complexity status of the problem has remained open even on the smaller class of permutation graphs. In this paper, we present a polynomial-time algorithm for solving the longest path problem on the class of cocomparability graphs. Our result resolves the open question for the complexity of the problem on such graphs, and since cocomparability graphs form a superclass of both interval and permutation graphs, extends the polynomial solution of the longest path problem on interval graphs and provides polynomial solution to the class of permutation graphs.     

Optical characterization of varnish films by spectroscopic ellipsometry for application in artwork conservation

The specific aim of this paper is to measure the optical constants of fresh varnish layers up to a thickness of 10 mum by spectroscopic ellipsometry. It is the first time that this technique has been used in artwork conservation and it may prove very promising due to its nondestructive character. Samples of fresh dammar varnish (natural resin) and Paraloid B72 (synthetic resin) applied on glass and carbon black acrylic paint were analyzed. Both varnishes were considered as perfect dielectrics, and the real part of their refractive index was described by the Cauchy model: n (lambda) = A + B/lambda(2) + C/lambda(4). The Cauchy coefficients for dammar varnish and Paraloid B72 were then determined for layers of known thickness. The ellipsometric data were fitted to a model, which includes a mixed varnish-air layer. The optical properties of this layer were calculated by the Bruggeman effective medium approximation. In the case of carbon black acrylic paint, another mixed layer (paint-varnish) was added to the model. The results are very close to the values given in the literature. Given the measurement reproducibility, the results show that ellipsometry can discriminate between dammar varnish and Paraloid B72. This is very important in artwork conservation studies, because it has been done by time-consuming, destructive techniques up to now. Future work includes measurements of other types of natural and synthetic varnishes, in an attempt to introduce a nondestructive method for picture varnish identification and aging studies.     

The Discriminant Value of Personality,Motivation, and Online Relationship Quality in Predicting Attraction to Online Social Support on Facebook

This study investigates the relationship between personality traits, user motivations, relationship quality, and attraction to online social support in a sample of young adults (N = 278) in Greece who use Facebook. Self-report questionnaires on personality, motives, relationship quality, online social support, and sociodemographic factors were administered. According to the results, men in contrast to women were significantly more attracted to online social support. Predictors of online relationship quality were the existence of close relationships, entertainment, and conscientiousness. Motives, personality, relationship quality, and gender were good predictors of attraction to online social support. Implications for psychologists and future research are discussed.     

Polymer-BaTiO3 composites: Dielectric constant and vapor sensing properties in chemocapacitor applications

In this work, composite materials, prepared by inclusion of various amounts of BaTiO₃ nanoparticles in PBMA and PHEMA polymer matrices, were characterized in respect to their dielectric properties and then used as the sensing layer of capacitive-type sensors. BaTiO₃ was found to be less effective in enhancing the permittivity of PHEMA, as compared to PBMA, in the range of 1 kHz–1 MHz, possibly due to the observed lower quality of dispersion in the polymer matrix and the higher polarity of the polymer in the former case. The response of the composite-based chemocapacitors to four vapor analytes, covering a wide range of dielectric constants, was studied in relation to the BaTiO₃ load. In all cases, with increasing amount of BaTiO₃ load, the absolute value of capacitance response was increased, due to the corresponding increase of the initial capacitance of the sensing composite layer. However, the corresponding normalized (to the initial capacitance of the sensing composite layer) capacitance values were reduced, due to the decreased volume fraction of the sorbing polymer material in the composite matrix. An exception to this trend, observed upon exposure of the PBMA/BaTiO₃ chemocapacitors to low humidity levels, is also presented and discussed. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

The nucleating effect of exfoliated graphite nanoplatelets and their influence on the crystal structure and electrical conductivity of polypropylene nanocomposites

The focus of this research is to investigate how exfoliated graphite nanoplatelets, xGnP™, (graphene sheets ∼10 nm thickness, ∼1 μm diameter), a nanomaterial developed by the Drzal group, affects the crystallization of semicrystalline thermoplastics i.e., polypropylene (PP). In addition, this study explores how the presence of xGnP in combination with the processing conditions used to make the xGnP-PP nanocomposites alter the crystal structure and electrical conductivity of these systems. The nanocomposites are fabricated (i) by melt mixing followed by injection molding and (ii) by coating PP powder with xGnP with sonication in isopropyl alcohol followed by compression molding. PP was found to nucleate on the graphene surface of xGnP that is an effective nucleating agent for the β-form of PP crystals at low concentrations. The β-form of PP crystals has higher impact strength and toughness compared to the more common occurring α-form. It is found that the aspect ratio and concentration of xGnP combined with the crystallization conditions can be used to engineer the crystal structure such as the population and size distribution of PP spherulites and alter the electrical conductivity of xGnP-PP nanocomposites. The reason is that the presence of many small spherulites nucleated by the xGnP disrupts the percolated network formed by the conductive particles and thus increases the concentration required to reach conductivity and alters the conductivity value.