Selective photo-oxidation of glucose

Biomass transformation into high-value chemicals has attracted attention according to the “green chemistry” principles. Low price and high availability make biomass one of the most interesting renewable resources as it provides the means to create sustainable alternatives to the oil-derived building blocks of the chemical industry In recent year, the need for alternative environmentally friendly routes to drive chemical reactions has in photocatalytic processes an interesting way to obtain valuable chemicals from various sources using the solar light as energy source. The purpose of this work was to use supported noble metal nanoparticles in the selective photo-oxidation of glucose through using visible light. Glucose was chosen as model molecule because it is the cheapest and the most common monosaccharide. Few studies about glucose photo oxidation have been conducted so far, and reaction mechanism is still not totally explained. The aim of this work was to systematically analyze and assess the impact of several parameters (eg. catalyst/substrate ratio, reaction time, effect of the solvent and light source) on the reaction pathway and to monitor the product distribution in order to draw a general reaction scheme for the photo oxidation of glucose under visible light. This study regards the reaction mechanism and the influence of several parameters, such as solvent, light power and substrate concentration. Furthermore, the work focuses on the influence of gold and silver nanoparticles and on the influence of metal loading. The glucose oxidation was monitored through the mass balance and the products selectivity. Reactions were evaluated in terms of glucose conversion, mass balance and selectivities towards arabinose and gluconic acid. In conclusion, this study is able to demonstrate that the photo oxidation of glucose under visible light is feasible; the full identification of the main products allows, for the first time, a comprehensive reaction mechanism scheme.

Can non-selective beta-blockers prevent hepatocellular carcinoma in patients with cirrhosis?

Hepatocellular carcinoma is the main liver-related cause of death in patients with compensated cirrhosis. The early phases are asymptomatic and the prognosis is poor, which makes prevention essential. We propose that non-selective beta-blockers decrease the incidence and growth of hepatocellular carcinoma via a reduction of the inflammatory load from the gut to the liver and inhibition of angiogenesis. Due to their effect on the portal pressure, non-selective beta-blockers are used for prevention of esophageal variceal bleeding. Recently, non-hemodynamic effects of beta-blockers have received increasing attention. Blockage of β-adrenoceptors in the intestinal mucosa and gut lymphatic tissue together with changes in type and virulence of the intestinal microbiota lead to reduced bacterial translocation and a subsequent decrease in the portal load of pathogen-associated molecular patterns. This may reduce hepatic inflammation. Blockage of β-adrenoceptors also decrease angiogenesis by inhibition of vascular endothelial growth factors. Because gut-derived inflammation and neo-angiogenesis are important in hepatic carcinogenesis, non-selective beta-blockers can potentially reduce the development and growth of hepatocellular carcinoma. Rodent and in vitro studies support the hypothesis, but clinical verification is needed. Different study designs may be considered. The feasibility of a randomized controlled trial is limited due to the necessary large number of patients and long follow-up. Observational studies carry a high risk of bias. The meta-analytic approach may be used if the incidence and mortality of hepatocellular carcinoma can be extracted from trials on variceal bleeding and if the combined sample size and follow up is sufficient.

Positron-emission tomography studies of cross-modality inhibition in selective attentional tasks: closing the "mind's eye".

It is a familiar experience that we tend to close our eyes or divert our gaze when concentrating attention on cognitively demanding tasks. We report on the brain activity correlates of directing attention away from potentially competing visual processing and toward processing in another sensory modality. Results are reported from a series of positron-emission tomography studies of the human brain engaged in somatosensory tasks, in both "eyes open" and "eyes closed" conditions. During these tasks, there was a significant decrease in the regional cerebral blood flow in the visual cortex, which occurred irrespective of whether subjects had to close their eyes or were instructed to keep their eyes open. These task-related deactivations of the association areas belonging to the nonrelevant sensory modality were interpreted as being due to decreased metabolic activity. Previous research has clearly demonstrated selective activation of cortical regions involved in attention-demanding modality-specific tasks; however, the other side of this story appears to be one of selective deactivation of unattended areas.

Movement trajectories in the presence of a distracting stimulus: Evidence for a response activation model of selective reaching

Consistent with action-based theories of attention, the presence of a nontarget stimulus in the environment has been shown to alter the characteristics of goal-directed movements. Specifically, it has been reported that movement trajectories veer away from (Howard & Tipper, 1997) or towards (Welsh, Elliott, & Weeks, 1999) the location of a nontarget stimulus. The purpose of the experiments reported in this paper was to test a response activation model of selective reaching conceived to account for these variable results. In agreement with the model, the trajectory changes in the movements appear to be determined by the activation levels of each competing response at the moment of response initiation. The results of the present work, as well as those of previous studies, are discussed within the framework of the model of response activation.

Towards a literacy of attention

In 1997, business trend analyst Linda Stone proposed the term "continuous partial attention" to characterise the contemporary experience of wanting to be ‘a live node on the network’. She argued that while it can be a positive and functional behaviour, it also has the potential to be disabling, compromising reflective and creative thought. Subsequent studies have explored the ways in which technology has slowly disrupted the idea and experience of a "centred" and "bounded" self. Studies of ‘Gen Y’ show the ease with which young people accommodate this multiplying of the self as they negotiate their partial friendships and networks of interest with family and work. In teaching and learning circles in tertiary education we talk a lot about problems of student ‘disengagement’. In characterising our challenge this way, are we undermining our potential to understand the tendencies of contemporary learners? This paper begins a consideration of how traditional models, frameworks and practices might oppose these partially engaged but continuously connected and interpersonal "dividuals". What questions does this provoke for learning environments towards harnessing yet counterpointing the crisis students might experience; to recognise but also integrate their multiple selves towards what they aim to become through the process of learning?

Why is there a gender gap in children presenting for Attention Deficit/Hyperactivity Disorder services?

This study addressed why girls are less likely to be referred for mental health services for attention deficit/hyperactivity disorder (ADHD) than boys. Ninety-six parents of children with elevated ADHD symptoms and 140 elementary school teachers read vignettes about children with ADHD. Half of the participants read vignettes with boys' names, and half read the same vignettes but with girls' names. Participants then rated their likeliness to seek or recommend services for the child in each vignette. Parents and teachers were less likely to seek or recommend services for girls than boys with ADHD, but results did not support the hypothesis that this is because girls are less disruptive than boys. Rather, differences in service seeking were explained by the fact that parents and teachers believed that learning assistance is less effective for girls than boys with ADHD.

Does lymphedema following breast cancer warrant clinical attention?

Secondary lymphedema (swelling) after breast cancer treatment usually develops on the hand, arm, shoulder, and/or breast on the treated side. It is commonly associated with the presence of other upper-body symptoms, such as pain and aching1; it impacts physical and psychosocial functioning and adversely influences quality of life.2 Moreover, it is considered incurable, progressive, and difficult to treat. Arguably, lymphedema is the most problematic and dreaded treatment-related complication of breast cancer.3

Pathologising difference, governing personality

Recent research has stressed the integral part played by teachers in both preliminary diagnosis and ongoing treatment of a range of conduct and personality disorders. Teachers are not only required to be aware of a variety of new categories of difference (Attention Deficit Disorder, Selective Mutism, Borderline Personality Disorder, Antisocial Personality Disorder, to name but a few), but are also now lauded for extending the role of education into new areas of social management. This paper will take issue with this understanding on two counts: first, teachers have always sought to mould the personalities of students, and the pathologisation of specific forms of conduct is simply a new tactic within a very old and familiar strategy. Second, schools do not simply discover disorders such as ADD as objective facts of nature. Rather, they are part of the process through which such differences are created, and by which individuals can be more effectively governed.

A disordered approach

It seems a new behaviour disorder is identified every week. Forms of conduct once simply regarded as part of the human condition, are rapidly being reinterpreted as types of mental illness. Individuals are no longer simply quiet or shy, they are reclassified as suffering from Generalised Social Phobia, or Selective Mutism, or Avoidant Personality Disorder. Others are no longer simply unpopular or obnoxious, they are reclassified as Borderline Personality Disorder, or Antisocial Personality Disorder. Still more are no longer lively or boisterous, they have Attention Deficit Hyperactivity Disorder, or Conduct Disorder, or Oppositional Defiance Disorder.

Human brain regions required for the dividing and switching of attention between two features of a single object

This combined PET and ERP study was designed to identify the brain regions activated in switching and divided attention between different features of a single object using matched sensory stimuli and motor response. The ERP data have previously been reported in this journal [64]. We now present the corresponding PET data. We identified partially overlapping neural networks with paradigms requiring the switching or dividing of attention between the elements of complex visual stimuli. Regions of activation were found in the prefrontal and temporal cortices and cerebellum. Each task resulted in different prefrontal cortical regions of activation lending support to the functional subspecialisation of the prefrontal and temporal cortices being based on the cognitive operations required rather than the stimuli themselves.

Maternal anxiety and attention problems in children at 5 and 14 years

Objective: This study examines the association between maternal anxiety from pregnancy to 5 years and child attention problems at 5 and 14 years. Method: Birth cohort of 3,982 individuals born in Brisbane between 1981 and 1983 are assessed. Self-reported measures of maternal anxiety are assessed at four time points. Maternal reports of child attention problems using Achenbach’s Child Behavior Checklist are assessed at 5 and 14 years. Results: Children of mothers experiencing anxiety during or after pregnancy are at greater risk of experiencing attention problems at 5 and 14 years. After adjusting for maternal age and child’s gender, antenatal anxiety is strongly associated with persistent attention problems (OR = 3.65, 95% CI = 2.19, 6.07). Children with chronically anxious mothers are 5.67 (95% CI = 3.56, 9.03) times more likely to have persistent attention problems. These associations remain consistent after adjusting for potential confounders. Conclusions: Maternal anxiety appears to increase the rate of child attention problems and identifies a need for treatment programs to have a dual focus—the mother and her child. (J. of Att. Dis. 2009; XX(X) 1-XX)