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1.
Wound Repair Regen ; 31(4): 542-546, 2023.
Article in English | MEDLINE | ID: mdl-37279099

ABSTRACT

The aim of this study was to evaluate the prevalence and extent of lower extremity Mönckeberg's Medial Calcific Sclerosis (MMCS) in patients with and without diabetes in patients admitted to the hospital for foot infections. This study retrospectively reviewed 446 patients admitted to the hospital with a moderate or severe foot infection. We defined diabetes based on ADA criteria and reviewed electronic medical records for demographics, medical history and physical examination data. Anterior-posterior and lateral foot radiographs were examined to identify the presence and extent of vascular calcification. We categorised MMCS based on anatomical location: ankle joint to the navicular-cuneiform joint, Lis Franc joint to metatarsophalangeal joints and distal to the metatarsophalangeal joints. The prevalence of MMCS was 40.6%. The anatomic extent of MMCS was 19.3% in the toes, 34.3% in the metatarsals and 40.6% in the hindfoot/ankle. Calcification was not common solely in the dorsalis pedis artery (DP) (3.8%) or solely in the posterior tibial artery (PT) (7.0%). Usually, both DP and PT arteries were affected by MMCS (29.8%). The prevalence of MMCS was higher in people with diabetes (in hindfoot and ankle [50.1% vs. 9.9%, p ≤ 0.01]; metatarsals [42.6% vs. 5.9%, p ≤ 0.01]; and toes [23.8% vs. 4.0%, p ≤ 0.01]). People with diabetes were 8.9 (CI: 4.5-17.8) times more likely to have MMCS than those without diabetes. This is a group that often has poor perfusion and needs vascular assessment. The high prevalence of MMCS raises questions about the reliability of the conventional segmental arterial Doppler studies to diagnose PAD.


Subject(s)
Diabetes Mellitus , Monckeberg Medial Calcific Sclerosis , Humans , Monckeberg Medial Calcific Sclerosis/diagnosis , Reproducibility of Results , Retrospective Studies , Wound Healing
2.
Natl Sci Rev ; 8(4): nwaa299, 2021 Apr.
Article in English | MEDLINE | ID: mdl-34691619

ABSTRACT

Chih-chen Wang is a distinguished biochemist and molecular biologist, and an Academician of the Chinese Academy of Sciences (CAS). From 2008 to 2013, she was a vice chairperson of the National Committee of the Chinese People's Political Consultative Conference (CPPCC). As a young researcher, Wang participated in research on insulin. Since the 1990s, she has been focusing on the study of protein folding, and has initiated a new research area of isomerase and molecular chaperones in China. In this interview, Chih-chen Wang elaborates on the social responsibility of scientists by drawing on both her scientific research and CPPCC experience. In Wang's view, what China really needs are intellectuals with independent thinking and strong social responsibility, who are able to provide the government valuable advice and communicate with the public to increase society's scientific literacy. She also hopes that female scientists can be more confident and gain greater attention and support from society.

3.
Opt Express ; 28(8): 12149-12156, 2020 Apr 13.
Article in English | MEDLINE | ID: mdl-32403714

ABSTRACT

Full-color smart displays, which act both as a display and as a high-speed visible light communication (VLC) transmitter, can be realized by the integration of red-green-blue micron-sized light emitting diodes (micro-LEDs) onto a common platform. In this work, we report on the integration of aluminum gallium indium phosphide red micro-LEDs onto diamond and glass substrates by micro-transfer printing and their application in VLC. The device on-diamond exhibits high current density and bandwidth operation, enabled by diamond's superior thermal properties. Employing an orthogonal frequency division multiplexing modulation scheme, error-free data rates of 2.6 Gbps and 5 Gbps are demonstrated for a single micro-LED printed on-glass and on-diamond, respectively. In a parallel configuration, a 2x1 micro-LED array achieves error-free data rates of 3 Gbps and 6.6 Gbps, on-glass and on-diamond, respectively.

4.
Opt Express ; 28(5): 6909-6917, 2020 Mar 02.
Article in English | MEDLINE | ID: mdl-32225928

ABSTRACT

We present integration of singulated micron-sized light emitting diodes (micro-LEDs) directly onto a silicon CMOS drive chip using a transfer printing method. An 8x8 micro-LED device array with individual control over each pixel is demonstrated with modulation bandwidths up to 50 MHz, limited by the large modulation depth of the driver chip. The 2 kHz frame rate CMOS driver also incorporates a Single Photon Avalanche Diode device thus allowing detection and transmission functionality on a single integrated chip. Visible light communications at data rates up to 1 Mbps, and time-of-flight ranging with cm-scale resolution are demonstrated using this hybrid integrated system.

5.
Opt Express ; 27(20): A1517-A1528, 2019 Sep 30.
Article in English | MEDLINE | ID: mdl-31684503

ABSTRACT

Integrated multi-color micron-sized light emitting diode (micro-LED) arrays have been demonstrated in recent years for display applications; however, their potential as visible light communication (VLC) transmitters is yet to be fully explored. In this work, we report on the fabrication and characterization of on-chip dual-color micro-LED arrays and their application in VLC. For this purpose, blue-green and blue-violet micro-LED arrays were fabricated by transfer printing blue-emitting micro-LEDs onto the substrate of green and violet micro-LEDs, respectively. The potential of these dual-color micro-LED arrays as VLC transmitters is demonstrated with respective error-free data rates of 1.79 and 3.35 Gbps, achieved by the blue-green and blue-violet devices in a dual wavelength multiplexing scheme.

6.
Anaesthesia ; 74(6): 741-750, 2019 Jun.
Article in English | MEDLINE | ID: mdl-30835822

ABSTRACT

Peri-operative dexmedetomidine can reduce rates of delirium immediately after surgery. We aimed to assess the effect of dexmedetomidine on cognition up to six postoperative months and its association with changes in serum concentrations of brain-derived neurotrophic factor on the third and seventh postoperative days. We randomly allocated 535 patients aged 65 years or more undergoing scheduled gastro-intestinal laparotomy to: intra-operative dexmedetomidine, 0.5 µg.kg-1 bolus followed by 0.4 µg.kg-1 .hr-1 infusion (n = 269), or placebo (n = 266). Dexmedetomidine reduced the rate of cognitive impairment: on the third postoperative day, 40/269 vs. 65/266, p = 0.006; on the seventh postoperative day, 31/269 vs. 49/266, p = 0.03 and at one postoperative month, 42/250 vs. 61/248, p = 0.04. Cognitive impairment at seven postoperative days was associated with changes in brain-derived neurotrophic factor concentrations on the third and seventh postoperative days; area under the receiver operating characteristic curve 0.63, p < 0.001 and 0.58, p = 0.016, respectively. Intra-operative dexmedetomidine reduced cognitive decline up to one postoperative month in elderly patients undergoing scheduled laparotomy, which was associated with changes in serum brain-derived neurotrophic factor.


Subject(s)
Cognitive Dysfunction/prevention & control , Dexmedetomidine/pharmacology , Hypnotics and Sedatives/pharmacology , Intraoperative Care/methods , Postoperative Complications/prevention & control , Aged , Aged, 80 and over , Brain-Derived Neurotrophic Factor/blood , Cognitive Dysfunction/blood , Female , Humans , Male , Postoperative Complications/blood , Prospective Studies
7.
Zhonghua Yi Xue Za Zhi ; 96(43): 3464-3469, 2016 Nov 22.
Article in Chinese | MEDLINE | ID: mdl-27903339

ABSTRACT

Objective: To investigate the effect of goal-directed haemodynamic management based on stroke volume variation (SVV), cardiac index (CI) and mean arterial blood pressure (MAP) on the postoperative outcome in elderly patients with fragile cardiac function undergoing gastrointestinal surgery. Methods: Ninety patients with fragile cardiac function, aged 65-90 years old, ASAⅡ or Ⅲ, NYHA Ⅱor Ⅲ, scheduled for abdominal surgery were enrolled in this study.The patients were randomly assigned to two groups: Experience anesthesia group (group E, n=45) and goal-directed hemodynamic management group (G group, n=45). After anesthesia induction, in group G, the SVV and CI were monitored by Vigileo and according SVV (≤12%), CI (≥2.5 L·min-1·m-2) and MAP (maintain the base value of ±20%) to adjust the preloaded infusion fluid and give positive inotropic drugs and positive pressure drugs; in group E, fluid and vasoactive agent were used according to the experience of anesthesiologist.Multi-mode monitoring anesthesia management using BIS, TCI of propofol, low-tidal-volume lung protective ventilation management strategy, body temperature protection, and postoperative multimodal analgesia techniques was performed in the two groups.Values of N-terminal pro-B-type natriuretic peptide (NT-proBNP) and cardiac troponin T (cTnT) were recorded before operation, at the end of operation, and postoperative 24 h. The incidence of myocardial infarction/angina, heart failure, arrhythmia and cerebral infarction, renal failure, length of hospitalization, and complications in 30-days after surgery were recorded by telephone follow-up. Results: Crystal, colloid, total liquid of group E were (1 110.20±332.00), (536.65±72.25), (1 677.20±424.44) ml and these of group G were (708.72±240.85), (414.41±74.31), (878.51±199.13) ml, respectively.Compared with group E, the fluid infusion were reduced in group G (t=6.057, 2.701, 9.742, all P<0.05). The lactic acid value of 24 hours after surgery in group G was significantly lower than that in group E [(0.89±0.31) mmol/L vs (1.11±0.43) mmol/L, t=-2.848, P<0.05]. Arterial partial pressure of oxygen at 24 hours after surgery in group G was higher than that in group E [(78.77±6.86) mmHg vs (76.46±10.96) mmHg, t=-1.108, P<0.05]. The length of hospitalization of group G was shorter than that of group E [(12.21±2.20) d vs (13.16±3.84) d, t=-1.341, P<0.05]. The incidence of total complication in hospital and in 30-days after surgery of group G were 10.26% and 5.13%, while these of group E were 29.73% and 24.32%, (χ2=4.545, 4.520, all P<0.05). ΔNT-proBNP1 (the base value of NT-proBNP's minus the value of NT-proBNP's at the end of the operation) and ΔNT-proBNP2 (the base value of NT-proBNP's minus the value of NT-proBNP's 24 hours postoperatively) of group G were 12.0(-291.0, 1 517.0) and 0(-6 770.0, 291.0), both higher than these of group E [0(-440.0, 200.0) and -12.0(-7 200, 22.0), (Z=-2.412, -2.163, all P<0.05)]. Conclusion: Goal-directed haemodynamic management based on SVV, CI and MAP could improve the outcome of the elderly patients with fragile heart function undergoing abdominal surgery.


Subject(s)
Digestive System Surgical Procedures , Heart , Hemodynamics , Aged , Aged, 80 and over , Goals , Humans , Monitoring, Physiologic , Natriuretic Peptide, Brain , Peptide Fragments , Postoperative Period , Propofol , Stroke Volume , Tidal Volume , Vasoconstrictor Agents
8.
Opt Express ; 23(13): 16565-74, 2015 Jun 29.
Article in English | MEDLINE | ID: mdl-26191668

ABSTRACT

Different size InGaN/GaN based micro-LEDs (µLEDs) are fabricated. An extremely high injection level above 16 kA/cm2 is achieved for 10 µm-diameter LED. The lateral current density and carrier distributions of the µLEDs are simulated by APSYS software. Streak camera time resolved photoluminescence (TRPL) results show clear evidence that the band-gap renormalization (BGR) effect is weakened by strain relaxation in smaller size µLEDs. BGR affects the relaxation of free carriers on the conduction band bottom in multiple quantum wells (MQWs), and then indirectly affects the recombination rate of carriers. An energy band model based on BGR effect is made to explain the high-injection-level phenomenon for µLEDs.

9.
Opt Express ; 23(7): 9329-38, 2015 Apr 06.
Article in English | MEDLINE | ID: mdl-25968763

ABSTRACT

We report the transfer printing of blue-emitting micron-scale light-emitting diodes (micro-LEDs) onto fused silica and diamond substrates without the use of intermediary adhesion layers. A consistent Van der Waals bond was achieved via liquid capillary action, despite curvature of the LED membranes following release from their native silicon growth substrates. The excellence of diamond as a heat-spreader allowed the printed membrane LEDs to achieve optical power output density of 10 W/cm(2) when operated at a current density of 254 A/cm(2). This high-current-density operation enabled optical data transmission from the LEDs at 400 Mbit/s.

10.
Am J Transplant ; 15(6): 1692-700, 2015 Jun.
Article in English | MEDLINE | ID: mdl-25645705

ABSTRACT

Here we introduce a novel method of transplanting human fetal kidneys into adult rats. To overcome the technical challenges of fetal-to-adult organ transplantation, we devised an arterial flow regulator (AFR), consisting of a volume adjustable saline-filled cuff, which enables low-pressure human fetal kidneys to be transplanted into high-pressure adult rat hosts. By incrementally withdrawing saline from the AFR over time, blood flow entering the human fetal kidney was gradually increased until full blood flow was restored 30 days after transplantation. Human fetal kidneys were shown to dramatically increase in size and function. Moreover, rats which had all native renal mass removed 30 days after successful transplantation of the human fetal kidney were shown to have a mean survival time of 122 days compared to 3 days for control rats that underwent bilateral nephrectomy without a prior human fetal kidney transplant. These in vivo human fetal kidney models may serve as powerful platforms for drug testing and discovery.


Subject(s)
Equipment and Supplies , Infusion Pumps , Kidney Transplantation , Kidney/embryology , Kidney/growth & development , Transplantation, Heterologous , Animals , Cell Proliferation/physiology , DNA-Binding Proteins/deficiency , DNA-Binding Proteins/genetics , Gene Knockout Techniques , Graft Survival/physiology , Humans , Kidney/blood supply , Kidney Cortex/cytology , Models, Animal , Nephrectomy , Rats , Rats, Mutant Strains , Regional Blood Flow/physiology
11.
Eur Rev Med Pharmacol Sci ; 17(5): 636-43, 2013 Mar.
Article in English | MEDLINE | ID: mdl-23543447

ABSTRACT

BACKGROUND: Lamivudine (LAM) and adefovir (ADV) are widely used in most Asian countries, though monotherapy is associated with the occurrence of resistance. AIM: To evaluate the efficiency of LAM and ADV combined treatment of chronic hepatitis B patients with compensated cirrhosis. PATIENTS AND METHODS: 206 eligible Chinese patients were randomly assigned in a 1:1 ratio to receive either LAM or ADV for the first 24 weeks. According to virologic response at 24 weeks, the patients either continued to monotherapy or switched to combined therapy for 48 weeks. After 48 weeks, all patients received LAM and ADV combined therapy for 96 weeks. RESULTS: Serum HBV DNA levels significantly decreased in patients with ADV or LAM monotherapy and continuously reduced after the combined therapy. Serum ALT normalized rate were 88.24% and 81.37% at week 48, and 95.74% and 87.36% at week 96 in ADV and LAM group respectively, comparing to 60.78% and 56.73% in ADV and LAM groups at baseline. The accumulated virological breakthrough rate at week 48 and 96 was significantly higher in LAM group. CONCLUSIONS: Both combination strategies were resulted in the long term virological, biochemical improvement in Chinese chronic hepatitis B patients with compensated cirrhosis.


Subject(s)
Adenine/analogs & derivatives , Antiviral Agents/therapeutic use , Hepatitis B, Chronic/drug therapy , Lamivudine/therapeutic use , Organophosphonates/therapeutic use , Adenine/therapeutic use , Adult , DNA, Viral/blood , Drug Therapy, Combination/methods , Female , Hepatitis B, Chronic/blood , Hepatitis B, Chronic/virology , Humans , Male , Prospective Studies
12.
Acta Anaesthesiol Scand ; 57(2): 236-42, 2013 Feb.
Article in English | MEDLINE | ID: mdl-22881281

ABSTRACT

BACKGROUND: Sufentanil is widely used in clinical anaesthesia because of its protective effects against ischaemia/reperfusion injury. Diabetes mellitus elevates the activity of glycogen synthase kinase-3ß (GSK-3ß), thereby increasing the permeability of mitochondrial transition pore. This study investigated the role of GSK-3ß in ameliorating the cardioprotective effect of sufentanil post-conditioning in diabetic rats. METHODS: Streptozotocin-induced diabetic rats and age-matched non-diabetic rats were subjected to 30 min of ischaemia and 120 min of reperfusion. Five minutes before reperfusion, rats were administered one of the following: a vehicle, sufentanil (1 µg/kg), or a GSK-3ß inhibitor SB216763 (0.6 mg/kg). Myocardial infarct size, cardiac troponin I, and the activity of GSK-3ß were then assessed. RESULTS: Sufentanil post-conditioning significantly reduced myocardial infarct size in the non-diabetic, but not in diabetic rats. SB216763 reduced infarct size in both diabetic and non-diabetic animals. Sufentanil-induced phospho-GSK-3ß was reduced 5 min after reperfusion in diabetic rats, but not in non-diabetic rats. CONCLUSIONS: Sufentanil treatment was ineffective in preventing against ischaemia/reperfusion in diabetic rats, which is associated with the activation of GSK-3ß. Our results also suggest that direct inhibition of GSK-3ß may provide a strategy to protect diabetic hearts against ischaemia/reperfusion injury.


Subject(s)
Anesthetics, Intravenous/therapeutic use , Cardiotonic Agents , Diabetes Mellitus, Experimental/physiopathology , Glycogen Synthase Kinase 3/metabolism , Reperfusion Injury/prevention & control , Reperfusion Injury/physiopathology , Sufentanil/therapeutic use , Anesthetics, Intravenous/pharmacology , Animals , Blood Pressure/drug effects , Blotting, Western , Diabetes Mellitus, Experimental/enzymology , Electrocardiography , Enzyme Inhibitors/pharmacology , Heart Rate/drug effects , Indoles/pharmacology , Male , Maleimides/pharmacology , Myocardial Infarction/pathology , Myocardium/pathology , Organ Size , Rats , Rats, Sprague-Dawley , Sufentanil/pharmacology , Troponin I/metabolism
13.
Anaesth Intensive Care ; 40(3): 505-10, 2012 05.
Article in English | MEDLINE | ID: mdl-22577917

ABSTRACT

Prior reports suggest that dreaming during anaesthesia is dependent on recovery time. Dreaming during sedation may impact patient satisfaction. The current study explores the incidence and content of dreaming during short-term sedation with sevoflurane or propofol and investigates whether dreaming is affected by recovery time. A total of 200 women undergoing first trimester abortion (American Society of Anesthesiologists physical status I) participated in the study. Patients were randomly assigned to receive either sevoflurane or propofol for short-term sedation. Patients were interviewed upon emergence with the modified Brice questionnaire. The results showed the incidence of dreaming was significantly different between anaesthesia groups with 60% (60/100) of the sevoflurane group and 33% (33/100) of the propofol group (P=0.000). However, recovery time did not significantly differ between groups. In the sevoflurane group, a greater number of dreamers could not recall what they had dreamed about (P=0.02) and more patients reported dreams that had no sound (P=0.03) or movement (P=0.001) compared with dreamers in the propofol group. Most participants reported dreams with positive emotional content and this did not significantly differ between groups. Anaesthesia administered had no effect on patient satisfaction. The results suggest that the incidence of dreaming was not affected by recovery time. Patient satisfaction was not influenced by choice of sedative and/or by the occurrence of dreaming during sevoflurane or propofol short-term sedation.


Subject(s)
Anesthetics, Inhalation , Conscious Sedation , Dreams/drug effects , Hypnotics and Sedatives , Methyl Ethers , Propofol , Abortion, Therapeutic , Adult , Anesthesia Recovery Period , Dreams/psychology , Emotions/physiology , Endpoint Determination , Female , Humans , Middle Aged , Patient Satisfaction , Sevoflurane , Socioeconomic Factors , Young Adult
14.
Poult Sci ; 90(3): 609-17, 2011 Mar.
Article in English | MEDLINE | ID: mdl-21325232

ABSTRACT

Both embryonic and adult neural stem cells (NSC) of rodents and humans have been isolated and cultured in vitro to date, and they are thought to have tremendous clinical promise in restoring the diseased or injured central nervous system. However, there are few counterpart reports on neural stem cells from birds. This study explored the isolation and culture system of duck neural stem and progenitor cells (NSPC) and investigated their major biological properties. Cells from the dorsal ventricular ridges of 10- to 13-d embryos were isolated, cultured, and purified by using a neurosphere assay. Growth kinetics and karyotype were analyzed. The differentiation potential of NSPC was detected by immunofluorescence. Apoptosis and acetylation level of histone 4 lysine 12 (H4K12) were assessed. Results indicated that the nestin-positive neurospheres derived from duck embryos were able to self-renew and differentiate into neurons, astrocytes, and oligodendrocytes, and were prone to be transfected with exogenous genes. Karyotype analysis showed that 95% (38 out of 40) of cells of the population were diploid. Apoptosis detection indicated that the apoptotic rate was elevated with increasing passage number and culture time. The cells were highly acetylated and exhibited typical NSPC properties. Efficiently transfected with fluorescent genes, they were available for gene therapy and suitable for research on intracellular distribution of proteins of interest.


Subject(s)
Ducks/embryology , Neural Stem Cells/cytology , Neural Stem Cells/physiology , Animals , Cells, Cultured , Gene Expression Regulation, Developmental/physiology , Green Fluorescent Proteins/metabolism , Karyotyping
15.
Anim Genet ; 41 Suppl 2: 159-65, 2010 Dec.
Article in English | MEDLINE | ID: mdl-21070291

ABSTRACT

Horses, like many domesticated species, have been selected for broad variation in skeletal size. This variation is not only an interesting model of rapid evolutionary change during domestication, but is also directly applicable to the horse industry. Breeders select for complex traits like body size and skeletal conformation to improve marketability, function, soundness and performance in the show ring. Using a well-defined set of 35 measurements, we have identified and quantified skeletal variation in the horse species. We collected measurements from 1215 horses representing 65 breeds of diverse conformation such as the American Miniature, Shetland Pony, Arabian Horse, Thoroughbred, Shire and Clydesdale. Principal components analysis has identified two key dimensions of skeletal variation in the horse. Principal component 1 is positively correlated with every measurement and quantifies overall body size. Principal component 2 captures a pattern of bone widths vs. lengths and thus quantifies variation in overall bone thickness. By defining these complex skeletal traits, we have created a framework for whole genome association studies to identify quantitative trait loci that contribute to this variation.


Subject(s)
Bone and Bones/anatomy & histology , Horses/anatomy & histology , Horses/genetics , Animals , Body Size , Genetic Variation , Phenotype
16.
Opt Express ; 17(19): 16436-43, 2009 Sep 14.
Article in English | MEDLINE | ID: mdl-19770858

ABSTRACT

We report what we believe to be the first use of organic nanostructures for efficient colour conversion of gallium nitride light emitting diodes (LEDs). The particular nanomaterials, based on star-shaped truxene oligofluorenes, offer an attractive alternative to inorganic colloidal quantum dots in the search for novel and functional 'nanophosphors'. The truxenes have been formed into a composite with photoresist and ink-jet printed onto microstructured gallium nitride LEDs, resulting in a demonstrator hybrid microdisplay technology with pixel size approximately 32 microm. The output power density of the hybrid device was measured to be approximately 8.4 mW/cm(2) per pixel at driving current density of 870.8A/cm(2) and the efficiency of colour conversion at drive current of 7 mA was estimated to be approximately 50%.

17.
Opt Express ; 17(26): 23522-9, 2009 Dec 21.
Article in English | MEDLINE | ID: mdl-20052059

ABSTRACT

We report on an approach to ultraviolet (UV) photolithography and direct writing where both the exposure pattern and dose are determined by a complementary metal oxide semiconductor (CMOS) controlled micro-pixellated light emitting diode array. The 370 nm UV light from a demonstrator 8 x 8 gallium nitride micro-pixel LED is projected onto photoresist covered substrates using two back-to-back microscope objectives, allowing controlled demagnification. In the present setup, the system is capable of delivering up to 8.8 W/cm2 per imaged pixel in circular spots of diameter approximately 8 microm. We show example structures written in positive as well as in negative photoresist.


Subject(s)
Lighting/instrumentation , Manufactured Materials/radiation effects , Photochemistry/instrumentation , Photography/instrumentation , Semiconductors , Computer-Aided Design , Equipment Design , Equipment Failure Analysis , Miniaturization , Ultraviolet Rays
18.
Opt Express ; 16(13): 9918-26, 2008 Jun 23.
Article in English | MEDLINE | ID: mdl-18575561

ABSTRACT

Micropixelated blue (470 nm) and ultraviolet (370 nm) AlInGaN light emitting diode ('micro-LED') arrays have been fabricated in flip-chip format with different pixel diameters (72 microm and 30 microm at, respectively, 100 and 278 pixels/mm(2)). Each micro-LED pixel can be individually-addressed and the devices possess a specially designed n-common contact incorporated to ensure uniform current injection and consequently uniform light emission across the array. The flip-chip micro-LEDs show, per pixel, high continuous output intensity of up to 0.55 microW/microm(2) (55 W/cm(2)) at an injection current density of 10 kA/cm(2) and can sustain continuous injection current densities of up to 12 kA/cm(2) before breakdown. We also demonstrate that nanosecond pulsed output operation of these devices with per pixel onaxis average peak intensity up to 2.9 microW/microm(2) (corresponding to energy of 45pJ per 22ns optical pulse) can be achieved. We investigate the pertinent performance characteristics of these arrays for micro-projection applications, including the prospect of integrated optical pumping of organic semiconductor lasers.


Subject(s)
Models, Theoretical , Nanotechnology/instrumentation , Semiconductors , Signal Processing, Computer-Assisted/instrumentation , Aluminum Compounds/chemistry , Computer Simulation , Energy Transfer , Equipment Design , Equipment Failure Analysis , Light , Scattering, Radiation
19.
Opt Express ; 16(23): 18933-41, 2008 Nov 10.
Article in English | MEDLINE | ID: mdl-19581984

ABSTRACT

We report on the integration of monodisperse semiconductor nanocrystal (NC) color converters onto gallium nitride ultraviolet micro-pixelated light-emitting diodes ('micro-LEDs'). Integration is achieved in a 'self-aligned' process by forming a nanocomposite of the respective NCs in a photocurable epoxy polymer. Blue, green, yellow and red NC/epoxy blend microstructures have been successfully integrated onto micro-pixelated LEDs by this technique and utilised for color conversion, resulting in a five color emission single chip. Optical output power density of up to about 166 mW/cm2 is measured; spectral emission at 609 nm gives an estimated optical-to-optical conversion as high as 18.2% at 30 mA driving current.


Subject(s)
Epoxy Compounds/chemistry , Lighting/instrumentation , Nanostructures/chemistry , Nanotechnology/instrumentation , Semiconductors , Computer-Aided Design , Crystallization/methods , Equipment Design , Equipment Failure Analysis , Gallium/chemistry , Indium/chemistry , Reproducibility of Results , Sensitivity and Specificity , Signal Processing, Computer-Assisted/instrumentation
20.
Opt Express ; 15(15): 9341-6, 2007 Jul 23.
Article in English | MEDLINE | ID: mdl-19547276

ABSTRACT

We report a 1.055-mum microchip VECSEL array which uses a microlens-patterned diamond both as a heatspreader and as an array of concave output mirrors. This configuration, which is suitable for laser array operation, is here exploited to perform a systematic study of a set of microchip lasers with the same semiconductor structure but different cavity properties. The transverse mode selection of individual VECSELs is found to depend on the mode-matching conditions and on the microlens aperture size. Mode-matched single-device emission in the fundamental mode (M2~1.1) with pump-limited output power of 70 mW is demonstrated.

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