Functionalised zinc oxide nanowire gas sensors : enhanced NO2 gas sensor response by chemical modification of nanowire surfaces

Surface coating with an organic self-assembled monolayer (SAM) can enhance surface reactions or the absorption of specific gases and hence improve the response of a metal oxide (MOx) sensor toward particular target gases in the environment. In this study the effect of an adsorbed organic layer on the dynamic response of zinc oxide nanowire gas sensors was investigated. The effect of ZnO surface functionalisation by two different organic molecules, tris(hydroxymethyl)aminomethane (THMA) and dodecanethiol (DT), was studied. The response towards ammonia, nitrous oxide and nitrogen dioxide was investigated for three sensor configurations, namely pure ZnO nanowires, organic-coated ZnO nanowires and ZnO nanowires covered with a sparse layer of organic-coated ZnO nanoparticles. Exposure of the nanowire sensors to the oxidising gas NO2 produced a significant and reproducible response. ZnO and THMA-coated ZnO nanowire sensors both readily detected NO2 down to a concentration in the very low ppm range. Notably, the THMA-coated nanowires consistently displayed a small, enhanced response to NO2 compared to uncoated ZnO nanowire sensors. At the lower concentration levels tested, ZnO nanowire sensors that were coated with THMA-capped ZnO nanoparticles were found to exhibit the greatest enhanced response. ΔR/R was two times greater than that for the as-prepared ZnO nanowire sensors. It is proposed that the ΔR/R enhancement in this case originates from the changes induced in the depletion-layer width of the ZnO nanoparticles that bridge ZnO nanowires resulting from THMA ligand binding to the surface of the particle coating. The heightened response and selectivity to the NO2 target are positive results arising from the coating of these ZnO nanowire sensors with organic-SAM-functionalised ZnO nanoparticles.

The macrophage-inducible C-type lectin, Mincle, is an essential component of the innate immune response to Candida albicans

The recognition of carbohydrate moieties by cells of the innate immune system is emerging as an essential element in antifungal immunity, but despite the number and diversity of lectins expressed by innate immune cells, few carbohydrate receptors have been characterized. Mincle, a C-type lectin, is expressed predominantly on macrophages, and is here shown to play a role in macrophage responses to the yeast Candida albicans. After exposure to the yeast in vitro, Mincle localized to the phagocytic cup, but it was not essential for phagocytosis. In the absence of Mincle, production of TNF-_ by macrophages was reduced, both in vivo and in vitro. In addition, mice lacking Mincle showed a significantly increased susceptibility to systemic candidiasis. Thus, Mincle plays a novel and nonredundant role in the induction of inflammatory signaling in response to C. albicans infection.

A new model to analyze metaphyseal bone healing in mice

Background: Despite the increasing clinical problems with metaphyseal fractures, most experimental studies investigate the healing of diaphyseal fractures. Although the mouse would be the preferable species to study the molecular and genetic aspects of metaphyseal fracture healing, a murine model does not exist yet. Using a special locking plate system, we herein introduce a new model, which allows the analysis of metaphyseal bone healing in mice. Methods: In 24 CD-1 mice the distal metaphysis of the femur was osteotomized. After stabilization with the locking plate, bone repair was analyzed radiologically, biomechanically, and histologically after 2 (n = 12) and 5 wk (n = 12). Additionally, the stiffness of the bone-implant construct was tested biomechanically ex vivo. Results: The torsional stiffness of the bone-implant construct was low compared with nonfractured control femora (0.23 ± 0.1 Nmm/°versus 1.78 ± 0.15 Nmm/°, P < 0.05). The cause of failure was a pullout of the distal screw. At 2 wk after stabilization, radiological analysis showed that most bones were partly bridged. At 5 wk, all bones showed radiological union. Accordingly, biomechanical analyses revealed a significantly higher torsional stiffness after 5 wk compared with that after 2 wk. Successful healing was indicated by a torsional stiffness of 90% of the contralateral control femora. Histological analyses showed new woven bone bridging the osteotomy without external callus formation and in absence of any cartilaginous tissue, indicating intramembranous healing. Conclusion: With the model introduced herein we report, for the first time, successful metaphyseal bone repair in mice. The model may be used to obtain deeper insights into the molecular mechanisms of metaphyseal fracture healing. © 2012 Elsevier Inc. All rights reserved.

‘Personal Response’ and English Teaching

A case study relating to secondary education, examining the teacher student relationship as it operates within the English classroom is the topic of this paper. It describes how a certain conception of 'personal response' to literature provided a means for the teacher/counsellor to form the ethical capacities of children. 'Personal response' is usually associated with the moment in which the child is freed to be most natural. But for all the emphasis upon the irreducibly individual nature of the 'genuinely felt response', this pedagogic exercise finds its place within a series of strategies designed both to cherish and correct the child, to nurture and to scrutinise, to guide and to reconstruct.

Flightless, secreted through a late endosome/lysosome pathway, binds LPS and dampens cytokine secretion.

Flightless (Flii) is upregulated in response to wounding and has been shown to function in wound closure and scarring. In macrophages intracellular Flii negatively modulates TLR signalling and dampens cytokine production. We now show that Flii is constitutively secreted from macrophages and fibroblasts and is present in human plasma. Secretion from fibroblasts is upregulated in response to scratch wounding and LPS-activated macrophages also temporally upregulate their secretion of Flii. Using siRNA, wild-type and mutant proteins we show that Flii is secreted via a late endosomal/lysosomal pathway that is regulated by Rab7 and Stx11. Flii contains 11 leucine rich repeat (LRR) domains in its N-terminus that have nearly 50% similarity to those in the extracellular pathogen binding portion of Toll-like receptor 4 (TLR4). We show secreted Flii can also bind LPS and has the ability to alter macrophage activation. LPS activation of macrophages in Flii depleted conditioned media leads to enhanced macrophage activation and increased TNF secretion compared to cells activated in the presence of Flii. These results show secreted Flii binds to LPS and in doing so alters macrophage activation and cytokine secretion, suggesting that like the intracellular pool of Flii, secreted Flii also has the ability to alter inflammation.

Genotype x culture media interaction effects on regeneration response of three indica rice cultivars

Interactive effects of genotypes with callus induction and regeneration media combinations on green plantlet regeneration response were studied for three indica rice (Oryza sativa L.) cultivars, IR-72, IR-54 and Karnal Local. Isolated mature-embryoswere used to derive scutellar callus and fifteen media combinations involvingMS, N6, R2, SK1 and some modifications were tested. Regeneration percentage as well as the shoot-bud induction frequency were influenced by genotype, callus induction medium, regeneration medium, interaction between genotype and the two media (callus induction and regeneration) as well the interaction between the callus induction medium and regeneration medium. Basal media combination of SK1m (callusing) and MS (regeneration) was found to be the best for cv. Karnal Local in which regeneration frequency of 88% and shoot-bud induction of 233% was observed. In IR-72, the highest regeneration frequency of 47.5% and shoot-bud induction frequency of 77% was obtained on MS-MS combination. In IR-54, highest regeneration frequency (25%) was recorded on MMS(N)-MMS(N) combination, whereas, highest frequency of shoot-bud induction (50%) was observed on MMS(S)-MS combination. Although genotype and the composition of the callus induction basal medium were the major determinants of regeneration response, an overall analysis of variation also revealed a significant interaction between the media used for de-differentiation (callusing) and re-differentiation (plantlet regeneration)

Osteopenia in a teenage boy presenting with previously undiagnosed guanidinoacetate methyltransferase (GAMT) deficiency and response to creatine supplementation

A 16 y.o. fully ambulant boy born to consanguineous Indian parents, presented for assessment of a fragility femoral neck fracture sustained against a background of autism and moderately severe intellectual disability. He had a past history of infantile eczema, and epilepsy treated with anticonvulsants from 2 to 10 years of age, with no further seizures following cessation of anticonvulsants. He had a thin body habitus (see Table 1) with long fingers and a high arched palate. He had no speech and negligible social interaction, but physical examination was otherwise unremarkable. Positive investigations revealed an undetectable serum creatinine and a urinary metabolic screen which showed an elevated GUA:Phe of 160 (< 36) and a decreased creatinine of 0.3 mmol/l (1.2–29.5) consistent with the diagnosis of guanidinoacetate methyltransferase(GAMT) deficiency. He was commenced on oral creatine 5 g three times daily. Despite improvement in physical activity, height and bone density, there was no discernable improvement in his intellectual functioning. Proton and phosphorous brain and leg magnetic resonance spectroscopy(MRS) was performed at baseline and showed an increased inorganic phosphorus peak and decreased phosphocreatine synthesis in brain and decreased creatine concentration in muscle. Following creatine treatment total brain creatine(1H-MRS) and phosphocreatine/ATP ratio (31P-MRS) content increased to 30% and 60% of control values, respectively. Brain GUA returned to normal levels.

Influence of plate bending stiffness on mechanical properties of healing fracture, mouse femora

Mechanically well-defined stabilization systems have only recently become available, providing standardized conditions for studying the role of the mechanical environment on mouse bone fracture healing. The aim of this study was to characterize the time course of strength recovery and callus development of mouse femoral osteotomies stabilized with either low or high flexibility (in bending and torsion) internal fixation plates. Animals were euthanized and femora excised at 14, 21, and 28 days post-osteotomy for microCT analysis and torsional strength testing. While a larger mineralized callus was observed in osteotomies under more flexible conditions at all time points, the earlier bridging of the mineralized callus under less flexible conditions by 1 week resulted in an earlier recovery of torsional strength in mice stabilized with low flexibility fixation. Ultimate torque values for these bones were significantly higher at 14 and 21 days post-osteotomy compared to bones with the more flexible stabilization. Our study confirms the high reproducibility of the results that are achieved with this new implant system, therefore making it ideal for studying the influence of the mechanical environment on murine fracture healing under highly standardized conditions.

Numerical simulation of a fractional mathematical model for epidermal wound healing

A number of mathematical models investigating certain aspects of the complicated process of wound healing are reported in the literature in recent years. However, effective numerical methods and supporting error analysis for the fractional equations which describe the process of wound healing are still limited. In this paper, we consider numerical simulation of fractional model based on the coupled advection-diffusion equations for cell and chemical concentration in a polar coordinate system. The space fractional derivatives are defined in the Left and Right Riemann-Liouville sense. Fractional orders in advection and diffusion terms belong to the intervals (0; 1) or (1; 2], respectively. Some numerical techniques will be used. Firstly, the coupled advection-diffusion equations are decoupled to a single space fractional advection-diffusion equation in a polar coordinate system. Secondly, we propose a new implicit difference method for simulating this equation by using the equivalent of the Riemann-Liouville and Gr¨unwald-Letnikov fractional derivative definitions. Thirdly, its stability and convergence are discussed, respectively. Finally, some numerical results are given to demonstrate the theoretical analysis.

Theorizing Police Response to Domestic Violence in Singapore: Police Subculture Revisited

This article focuses on the well documented, yet potentially contested concept of rank-and-file policesubculture to conceptualize policeresponse to situations of domesticviolence in Singapore. It argues that the utility of the concept to explaining police behavior is often undermined by an all-powerful, homogenous, and deterministic conception of it that fails to take into account the value of agency in police decision-making and the range of differentiated policeresponse in situations of domesticviolence. Through reviewing the literature on policeresponse to domesticviolence, this study called for the need to rework the concept of policesubculture by treating it as having a relationship with, and response to, the structural conditions of policing, while retaining a conception of the active role played by street-level officers in instituting a situational practice. Using Pierre Bourdieu's relational concepts of ‘habitus’ and ‘field,’ designating the cultural dispositions of policesubculture and structural conditions of policing respectively, the study attempted to reconceptualize the problem of policing domesticviolence with reference to the Singaporean context.