Close-packed hemiellipsoid arrays: A photonic band gap structure patterned by nanosphere lithography

A self-assembled hexagonal close-packed hemiellipsoidal photonic crystal structure was fabricated on GaN material. An ordered monolayer silica nanosphere coating served as a hard mask in an inductively coupled plasma etching process. The shape of the arrayed hemiellipsoids can be controlled by adjusting the etch selectivities and durations according to the fabrication model. The existence of a photonic band gap is established through planar transmissivity measurement whereby a transmission dip centered at 440 nm was identified. A threefold enhancement in light extraction was achieved, as determined from the measured angular photoluminescence emission pattern. © 2009 American Institute of Physics.published_or_final_versio

Room temperature photonic crystal band-edge lasing from nanopillar array on GaN patterned by nanosphere lithography

An ordered GaN nanopillar array fabricated by nanosphere lithography exhibited room temperature photopumped lasing via the photonic crystal band-edge effect. With a monolayer of self-assembled nanospheres as hard mask, the ordered pattern was transferred to the sample to form nanopillars by inductively coupled plasma dry etch. Under pulsed optical excitation, room temperature lasing with a low lasing threshold of 30 mJ/ cm2 was achieved. The dominant lasing peak, centered at 415.6 nm, corresponds to a band-edge mode at the -point of the band diagram. A Q factor in the range of 600-700, and spontaneous emission coupling factor of 0.021 were evaluated. © 2010 American Institute of Physics.published_or_final_versio

Evaluation of InGaN/GaN light-emitting diodes of circular geometry

Blue GaN light emitting diodes (LEDs) in the shape of cuboids and circular disks have been fabricated by laser micromachining. The proposed circular geometry serves to enhance overall light extraction on a macro-scale and to improve uniformity of the emission pattern due to the rotational symmetry of the chip. Analysis of the chip shaping effect is carried out by ray-tracing simulations and further supported with mathematical modeling using ideal LED models, and subsequently verified with fabricated devices. In comparison, a 10% improvement in overall emission was observed for circular LEDs over the regular cuboids, consistent with simulations and calculations. The measured emission pattern from the circular LED confirms the axial symmetry of the emission beam. © 2009 Optical Society of America.published_or_final_versio

Association of More Negative Attitude towards Commencing Insulin with Lower Glycosylated Hemoglobin (HbA1c) Level: A survey on Insulin-naïve Type 2 Diabetes Mellitus Chinese Patients

Aims: This study examined the correlation between socio-demographic and clinical characteristics; and attitudes towards commencing insulin in Chinese primary care patients with Type 2 Diabetes Mellitus (DM). Method: A cross-sectional survey was conducted on 303 insulin-naïve Type 2 DM patients recruited from 15 primary care clinics across Hong Kong using the Chinese Attitudes to Starting Insulin Questionnaire (Ch-ASIQ). Subject selection criteria were patients on maximal oral anti-diabetes treatment who needed to commence insulin therapy. Linear regression was used to identify correlations between age, sex, educational level, occupation, body mass index, diabetes disease duration, laboratory test indicating disease control and biochemical markers including glycosylated hemoglobin (HbA1c) level , low density lipoprotein level and estimated glomeruli filtration rate, and presence of diabetic complications with the four sub-scales (self-image and stigmatization; factors promoting self-efficacy; fear of pain or needles; time and family support ) and the overall Ch-ASIQ score. Results: The most prevalent negative attitude was ‘fear of needle injections’ (70.1%). The most common positive attitude was ‘I can manage the skill of injecting insulin’ (67.5%). The mean Ch-ASIQ score of 2.50 (S.D.=0.38) was equal to the mid-score, which signified an overall ambivalent attitude among the study population. Women scored significantly higher in the fear of pain or needles subscale (p=0.011) and had an overall more negative attitude towards commencing insulin (p=0.016). Subjects with lower HbA1c levels also had a significantly lower Ch-ASIQ sum score (p=0.048) indicating a more negative attitude towards commencing insulin. Conclusion: In Chinese primary care patients with Type 2 DM, the need to commence insulin was associated with a number of negative emotions, which lead to a lower motivation to accept treatment. Perception of need as indicated by HbA1c level may be an important influencing factor determining a patient’s overall attitude towards starting insulin. Fortunately, in our setting, the injection technique does not appear to be a major barrier. However, needle fears are common, especially amongst women. Target interventions to acknowledge and help them to overcome their fears are essential before insulin treatment is commenced.published_or_final_versio

Geometrical shaping of InGaN light-emitting diodes by laser micromachining

Geometrical shaping of InGaN light-emitting diodes (LEDs) by laser micromachining is introduced. The sapphire substrate is shaped with inclined sidewalls at 50, serving as a prism favoring light redirection for out-coupling from the top window. Compared to conventional cuboid LEDs with a calculated light extraction efficiency next of 18.3%, these shaped LEDs offers a pronounced increase in next of up to 85.2%, verified by experimental results. © 2009 IEEE.published_or_final_versio

Growth of non-polar InGaN quantum dots with an underlying AlN/GaN distributed Bragg reflector by metal-organic vapour phase epitaxy

Non-polar (11-20) InGaN quantum dots (QDs) have been grown using a modified droplet epitaxy method by metal-organic vapour phase epitaxy on top of a 15-period AlN/GaN distributed Bragg reflector (DBR) on a-plane GaN pseudo-substrate prepared by epitaxial lateral overgrowth (ELOG), in which the QDs are located at the centre of a ca. 180 nm GaN layer. The AlN/GaN DBR has shown a peak reflectivity of ~80% at a wavelength of ~454 nm with a 49 nm wide, flat stop-band. Variations in layer thicknesses observed by cross-sectional scanning transmission electron microscopy have been identified as the main source of degradation of the DBR reflectivity. The presence of trenches due to incomplete coalescence of the ELOG template and the formation of cracks due to relaxation of tensile strain during the DBR growth may distort the DBR and further reduce the reflectivity. The DBR top surface is very smooth and does not have a detrimental effect on the subsequent growth of QDs. Enhanced single QD emission at 20 K was observed in cathodoluminescence.This work has been funded by the EPSRC (Grant No. EP/H047816/1 and EP/J001627/1).This is the final version of the article. It first appeared from Elsevier via http://dx.doi.org/10.1016/j.spmi.2015.10.00

Development and Validation of the Chinese Attitudes to Starting Insulin Questionnaire (Ch-ASIQ) for Primary Care Patients with Type 2 Diabetes

Objectives: To develop and evaluate the psychometric properties of a Chinese questionnaire which assesses the barriers and enablers to commencing insulin in primary care patients with poorly controlled Type 2 diabetes. Research Design and Method: Questionnaire items were identified using literature review. Content validation was performed and items were further refined using an expert panel. Following translation, back translation and cognitive debriefing, the translated Chinese questionnaire was piloted on target patients. Exploratory factor analysis and item-scale correlations were performed to test the construct validity of the subscales and items. Internal reliability was tested by Cronbach's alpha. Results: Twenty-seven identified items underwent content validation, translation and cognitive debriefing. The translated questionnaire was piloted on 303 insulin naïve (never taken insulin) Type 2 diabetes patients recruited from 10 government-funded primary care clinics across Hong Kong. Sufficient variability in the dataset for factor analysis was confirmed by Bartlett's Test of Sphericity (P 0.4 and Eigenvalues >1. Total variance for the 10 factors was 66.22%. Kaiser-Meyer-Olkin measure was 0.725. Cronbach's alpha coefficients for the first four factors were ≥0.6 identifying four subscales to which 13 items correlated. Remaining sub-scales and items with poor internal reliability were deleted. The final 13-item instrument had a four scale structure addressing: 'Self-image and stigmatization'; 'Factors promoting self-efficacy; 'Fear of pain or needles'; and 'Time and family support'. Conclusion: The Chinese Attitudes to Starting Insulin Questionnaire (Ch-ASIQ) appears to be a reliable and valid measure for assessing barriers to starting insulin. This short instrument is easy to administer and may be used by healthcare providers and researchers as an assessment tool for Chinese diabetic primary care patients, including the elderly, who are unwilling to start insulin. © 2013 Fu et al.published_or_final_versio

The Clinical Utility of SUDOSCAN in Chronic Kidney Disease in Chinese Patients with Type 2 Diabetes

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Structure and strain relaxation effects of defects in In<inf>x</inf>Ga<inf>1-x</inf>N epilayers

The formation of trench-defects is observed in 160 nm-thick InxGa1-xN epilayers with x ≤ 0.20, grown on GaN on (0001) sapphire substrates using metalorganic vapour phase epitaxy. The trench-defect density increases with increasing indium content, and high resolution transmission electron microscopy shows an identical structure to those observed previously in InGaN quantum wells, comprising meandering stacking mismatch boundaries connected to an I1-type basal plane stacking fault. These defects do not appear to relieve in-plane compressive strain. Other horizontal sub-interface defects are also observed for these samples and are found to be pre-existing threading dislocations which form half-loops by bending into the basal-plane, and not basal-plane stacking faults, as previously reported by other groups. The origins of these defects are discussed, and are likely to originate from a combination of the small in-plane misorientation of the sapphire substrate and the thermal mismatch strain between the GaN and InGaN layers grown at different temperatures.This work was funded in part by the Cambridge Commonwealth trust and the EPSRC. SKR is funded through the Cambridge-India Partnership Fund and Indian Institute of Technology Bombay via a scholarship. SKR also acknowledges funds from St. John’s College. MAM acknowledges support from the Royal Society through a University Research Fellowship.This is the accepted manuscript version. The final version is available from AIP at http://scitation.aip.org/content/aip/journal/jap/116/10/10.1063/1.4894688

An alternative to a randomised control design for assessing the efficacy and effectiveness of bracing in adolescent idiopathic scoliosis

Randomised controlled trials (RCTs) that assessed the efficacy of bracing for adolescent idiopathic scoliosis have suffered from small sample sizes, low compliance and lack of willingness to participate. The aim of this study was to assess the feasibility of a comprehensive cohort study for evaluating both the efficacy and the effectiveness of bracing in patients with adolescent idiopathic scoliosis. Patients with curves at greater risk of progression were invited to join a randomised controlled trial. Those who declined were given the option to remain in the study and to choose whether they wished to be braced or observed. Of 87 eligible patients (5 boys and 63 girls) identified over one year, 68 (78%) with mean age of 12.5 years (10 to 15) consented to participate, with a mean follow-up of 168 weeks (0 to 290). Of these, 19 (28%) accepted randomisation. Of those who declined randomisation, 18 (37%) chose a brace. Patients who were more satisfied with their image were more likely to choose bracing (Odds Ratio 4.1; 95% confidence interval 1.1 to 15.0; p = 0.035). This comprehensive cohort study design facilitates the assessment of both efficacy and effectiveness of bracing in patients with adolescent idiopathic scoliosis, which is not feasible in a conventional randomised controlled trial.postprin