412 research outputs found

    Understanding the twist-bend nematic phase: the characterisation of 1-(4-cyanobiphenyl-4'-yloxy)-6-(4-cyanobiphenyl-4'--yl)hexane (CB6OCB) and comparison with CB7CB

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    The synthesis and characterisation of the nonsymmetric liquid crystal dimer, 1-(4-cyanobiphenyl-40-yloxy)-6- (4-cyanobiphenyl-40-yl)hexane (CB6OCB) is reported. An enantiotropic nematic (N)–twist-bend nematic (NTB) phase transition is observed at 109 1C and a nematic–isotropic phase transition at 153 1C. The NTB phase assignment has been confirmed using polarised light microscopy, freeze fracture transmission electron microscopy (FFTEM), 2H-NMR spectroscopy, and X-ray diffraction. The effective molecular length in both the NTB and N phases indicates a locally intercalated arrangement of the molecules, and the helicoidal pitch length in the NTB phase is estimated to be 8.9 nm. The surface anchoring properties of CB6OCB on a number of aligning layers is reported. A Landau model is applied to describe high-resolution heat capacity measurements in the vicinity of the NTB–N phase transition. Both the theory and heat capacity measurements agree with a very weak first-order phase transition. A complementary extended molecular field theory was found to be in suggestive accord with the 2H-NMR studies of CB6OCB-d2, and those already known for CB7CB-d4. These include the reduced transition temperature, TNTBN/TNI, the order parameter of the mesogenic arms in the N phase close to the NTB–N transition, and the order parameter with respect to the helix axis which is related to the conical angle for the NTB phase.Postprint (published version

    Cytotoxic Activity of Essential Oils of Some Species from Lamiaceae Family

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    Cancer is considered one of the most lethal diseases in the world, with a prevalence of 439.2 cases and 163.5 deaths per 100,000 inhabitants, in the period from 2011 to 2015; this disease has a greater impact in underdeveloped countries. For the treatment of this disease, a combination of chemotherapy with surgery or radiation is generally used, however, it is not exempt from adverse effects or resistance of the tumor to this type of treatment, for this reason the search for new treatments is constant. The plants are a possible source to achieve this; Lamiaceae is a family of plants widely distributed on the planet and has been used traditionally for the treatment of different diseases, and various essential oils with the potential for cancer treatment have been isolated from this species. The scope of this review is to present 46 essential oils isolated from different species of Lamiaceae which have been tested against different cancer cell lines

    The Impact of Depression on the Functional Outcome of the Elderly Stroke Victim from a Gender Perspective: A Systematic Review

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    (1) Background: The aim of this systematic review focused on analyzing the impact of depression on the functional outcome of the elderly stroke victim and how this disorder affects both the female and the male population. (2) Methods: We conducted a systematic review using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The review was registered in PROSPERO (ID 346284). The systematic search for clinical trials was performed in the databases Pubmed, Otseeker, Scopus, Web of Science, Psycinfo, Medline Complete, ScienceDirect, SciELO, and Dialnet. Articles were selected according to the inclusion and exclusion criteria, including those dealing with post-stroke depression in adults whose psychological status had changed. Studies that only assessed the psychological state of caregivers were excluded. (3) Results: In total, 609 articles were identified, of which 11 randomized controlled trials were finally included in the review. The results indicate that post-stroke depression influences the recovery of functionality and quality of life. In addition, the need to detect the mood of the adult population after the stroke and to provide individualized treatment according to the characteristics of the person is highlighted. (4) Conclusions: This systematic review shows how early detection of post-stroke depressive symptoms can improve the degree of disability and quality of life of the person, especially in women.The APC was funded by the University of Malaga. Partial funding for open access charge: Universidad de Málag

    Terpenes from Natural Products with Potential Anti-Inflammatory Activity

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    The development and progression of many diseases is related with an inflammatory process, which could affect different organs or tissues. Currently, many drugs are used to treat inflammation. However, some of these compounds induce severe side effects. For this reason, the search of new therapeutic options for the treatment of inflammation is very desirable. Medicinal plants have been an interesting source for obtaining new active compounds, including several terpenes and terpenoids with anti-inflammatory activity. This book chapter includes 62 sesquiterpenes, 34 diterpenes, and 22 triterpenes with anti-inflammatory activity. The anti-inflammatory effect was evaluated using in vitro, in vivo, and both models. These terpenes were obtained from 44 plant species belonging to 25 botanical families. Eight of theses species belong to the Asteraceae family and four to Lamiaceae family, respectively, and the other species belong to 13 different botanical families, one sesquiterpene was obtained from a sponge and two diterpenes were isolated from corals

    Cytotoxic and Antitumoral Activities of Compounds Isolated from Cucurbitaceae Plants

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    The WHO says that annual cases of cancer will increase from 14 million in 2012 to 22 million in the next two decades. Cancer is the second cause of death in the world; in 2015, it caused 8.8 million deaths. On the other hand, it is necessary to consider that 70% of the total deaths due to this disease occur in developing countries, who have the least resources to acquire the drugs of choice for the treatment of this disease. Although there are treatments and these are effective, there are currently cases of resistance to drugs used to treat this disease, which has led to the search for new sources of drugs or compounds effective against the cancer being active; plants are the possible sources to achieve this. Cucurbitaceae is a family of plants widely distributed on the planet which has been used traditionally for the treatment of this disease and from they have been isolated different cucurbitanes. These compounds possess a wide biological activity, antidiabetic, anti-inflammatory, hepatoprotective, or cytotoxic and antitumoral effects. The aim of this review is to present 51 cucurbitacin compounds and 2 with different structures isolated from Cucurbitaceae plants with cytotoxic or antitumoral activity

    Sensory Profile of Greek Islands Thyme Honey

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    The sensory profiles of thyme honey from the Greek islands with different thymus pollen grain contents (A: >60%, B: 40–60%, and C: 18–40%) were studied. The results of the physico-chemical analyses fulfilled the criteria set by international quality standards and, specifically, Greek legislation (moisture content 20 DN). The sensory results showed that there were significant differences between groups with different pollen grain contents (p < 0.01) for all attributes except for floral aroma, with the Group A samples being the lightest in color (4.9 ± 1.8) and having the highest floral odor intensity (5.0 ± 2.0) and salty taste (3.5 ± 1.1). Additionally, samples with the highest pollen grain content (i.e., Group A) had olfactory notes of wood/wax/resin and a chemical aroma

    La caricatura en la Primavera Árabe: de la libertad de expresión al arte de resistencia a través de las redes sociales

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    La libertad de expresión en el mundo árabe sólo ha sido posible con el desarrollo de las caricaturas. Este hecho se materializó con la Primavera Árabe y el desarrollo del ciberespacio y las redes sociales, hasta tal punto en que se convirtieron en un arte de resistencia. Los objetivos, por tanto, son: (1) analizar la caricatura en el mundo árabe como forma de libertad de expresión, (2) estudiar la evolución de las caricaturas durante la Primavera Árabe y (3) examinar la función de las redes sociales en relación a las caricaturas. De este modo, la metodología es cualitativa, por lo que se han recopilado datos que han sido analizados exhaustivamente, utilizándose como fuente primaria las caricaturas Ali Ferzat, ya que muestran una clara evolución antes y después de la Primavera Árabe. Con todo, las conclusiones que se aprecian son: (1) la caricatura ha sido la única forma de libertad de expresión, (2) la caricatura puede ser considerada un medio de comunicación alternativo y (3) la caricatura se ha convertido en un arte de resistencia gracias al desarrollo de las redes sociales.The only way of freedom of speech in the Arab world is political cartoons. This issue crystalized in the Arab Spring due to the development of cyberspace and social media in the Arab world. As a result, these political cartoons became art of resistance. In this sense, the objectives of this research are: (1) to analyze political cartoons in the Arab world as a form of freedom of speech; (2) to study the evolution of political cartoons in the Arab Spring; and (3) to examine the function of social media and cyberspace as regard political cartoons. Therefore, this is a qualitative research in which a large amount of data has been analyzed in an exhaustive way. The primary source is ʿAlī Farzāt’s cartoons on the grounds that they show a clear evolution of political cartoons in the Arab world. As consequence, the conclusions of this research are: (1) political cartoons have been the only form of freedom of speech in the Arab world; (2) political cartoons are an alternative media; and (3) political cartoons are an art of resistance due to social media and cyberspace

    Defining the role of neutrophil-to-lymphocyte ratio in COPD: a systematic literature review

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    COPD is characterized by a pulmonary and systemic inflammatory process. Several authors have reported the elevation of multiple inflammatory markers in patients with COPD; however, their use in routine clinical practice has limitations. The neutrophil-to-lymphocyte ratio (NLR) is a useful and cost-effective inflammatory marker derived from routine complete blood count. We performed a systematic literature review using the PRISMA statement. Twenty-two articles were included, recruiting 7,601 COPD patients and 784 healthy controls. Compared with controls, COPD patients had significantly higher NLR values. We found a significant correlation between the NLR and clinical/functional parameters (FEV1, mMRC, and BODE index) in COPD patients. Elevation of the NLR is associated with the diagnosis of acute exacerbation of COPD (pooled data propose a cut-off value of 3.34 with a median sensitivity, specificity, and area under the curve of 80%, 86%, and 0.86, respectively). Additionally, increased NLR is also associated with the diagnosis of a bacterial infection in exacerbated patients, with a cut-off value of 7.30, although with a low sensitivity and specificity. The NLR is an independent predictor of in-hospital and late mortality after exacerbation. In conclusion, the NLR could be a useful marker in COPD patients; however, further studies are needed to better identify the clinical value of the NLR

    Distinctive dielectric properties of nematic liquid crystal dimers

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    We provide an overview of the effect of the molecular structure on the dielectric properties of dimers exhibiting nematic and twist-bend nematic phases with special focus on how the conformational distribution changes are reflected by the dielectric behaviour. Nematic dimers show distinctive dielectric properties which differ from those of archetypical nematic liquid crystals, as for example, unusual temperature dependence of the static permittivity or dielectric spectra characterised by two low-frequency relaxation processes with correlated strengths. The interpretation of such characteristic behaviour requires that account is taken of the effect of molecular flexibility on the energetically favoured molecular shapes. The anisotropic nematic interactions greatly influence the conformational distribution. Dielectric behaviour can be used to track those conformational changes due to dependence of the averaged molecular dipole moment on the averaged molecular shape. Results for a number of dimers are compared and analysed on the basis of the influence of details of the molecular structure, using a recently developed theory for the dielectric properties of dimers.Postprint (author's final draft

    Sensory Profile and Physico-Chemical Properties of Artisanal Honey from Zulia, Venezuela

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    The physico-chemical parameters and the sensory profile were determined in honeys from apiaries of the Mara and Maracaibo of Zulia State (Venezuela). The analysis of variance showed that there were no significant differences in the mean value between apiaries for most of the physicochemical parameters and sensory attributes. The obtained value for pH (3.58–4.08), free acidity (30.9–36.0 meq/kg), lactone acidity (9.0–14.3 meq/kg), total acidity (42.1–46.0 meq/kg), moisture content (19.1–20.0%), diastase activity (8.11–12.7 ºG), colour intensity (41.5–86.6 mm Pfund), hydroxymethylfurfural (15.7–26.0 mg/kg), and electrical conductivity (0.33–0.52 mS/cm) were within the criteria set by international quality regulations. The sensory profile of these honeys is characterized by being amber in colour, with a floral, acid fruit, balsamic and animal odour/aroma, a sweet, slightly acid taste, and by being fluid and of a medium persistence
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