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Background The prevalence of adverse food reactions in patients with chronic inhalant diseases has seldom been studied in China. This study is to investigate the prevalence of adverse food reactions and the symptoms caused in respiratory patients. Methods Respiratory patients in allergy clinics were asked to complete a questionnaire. Patients’ information such as age, gender, family history of allergy, and adverse reactions to a list of 48 foods and the symptoms caused, was recorded. Multivariate analyses were performed to determine the prevalence of adverse food reactions and their associated symptoms. Results 459 subjects, with an average age of 32 years old, completed the questionnaire; 45.3% were male. Among the 459 subjects, 38.1% (175/459) had an adverse reaction to food: 13.6% had an adverse food reaction to crab, 12.4% had an adverse food reaction to shrimp; and 9.9% had an adverse reaction to shellfish. Peach and nectarine were also shown to be common causative foods with 6.8% of the study group showing an adverse reaction to peach and 5.2% to nectarine. Seafood mainly caused skin symptoms and fruits gave rise to more throat, oral, and gastrointestinal problems. Conclusion The prevalence of adverse food reactions is high for patients with respiratory diseases. This indicates that adverse food reactions should be considered in the treatment and management of patients with chronic inhalant diseases. Electronic supplementary material The online version of this article (10.1186/s13223-017-0228-3) contains supplementary material, which is available to authorized users.

While good ohmic contact formation has been achieved on both p-GaN and n-AlGaN surfaces, the turn-on and operating voltages of AlGaN-based deep-ultraviolet light-emitting diodes (DUV-LEDs) remain very high. We find that this critical problem is mainly caused by the large difference between the annealing temperatures required for ohmic contact formation on the p-GaN and high Al-fraction n-AlGaN surfaces. We studied the effects of the high-temperature annealing treatments required for n-ohmic contact formation on the subsequent p-ohmic contact formation process in DUV-LEDs. The results show that post-annealing treatment at high temperature is necessary to form an ohmic contact on n-Al0.7Ga0.3N, but a treatment temperature of 900°C or more could cause severe degradation of the specific contact resistivity and the bulk resistivity of p-GaN. We conclude that 900°C is the optimum temperature to form an ohmic contact on n-Al0.7Ga0.3N in DUV-LEDs, where p-GaN and n-Al0.7Ga0.3N act as the p- and n-ohmic contact layers, respectively. We also found that the specific contact resistivity of p-GaN can be reduced by an additional low-temperature annealing treatment after the high-temperature annealing step; this effect can be attributed to the enhancement of the hole concentration in the p-GaN surface contact region. Finally, DUV-LEDs that emit at 280 nm were fabricated using four different annealing treatments during processing. A considerable reduction in the series resistance and thereby in the operating voltage was confirmed using the annealing process proposed above, consisting of a high-temperature anneal at 900°C followed by a low-temperature anneal at 500°C for 3 min.

Hexagonal boron nitride (h-BN) is an attractive wide-bandgap material for application to emitters and detectors operating in the deep ultraviolet (DUV) spectral region. The optical transmittance of h-BN in the DUV region is particularly important for these devices. We report on the deposition of thick h-BN films (&gt, 200 nm) on Al0.7Ga0.3N templates via radio-frequency sputtering, along with the realization of ultrahigh transmittance in the DUV region. The fraction of the gas mixture (Ar/N2) was varied to investigate its effects on the optical transmittance of BN. DUV light transmittance of as high as 94% was achieved at 265 nm. This value could be further enhanced to exceed 98% by a post-annealing treatment at 800 &deg, C in a N2 ambient for 20 min. The phase of the highly DUV&ndash, transparent BN film was determined to be a purely hexagonal structure via Raman spectra measurements. More importantly, these deposition processes were performed at a low temperature (300 &deg, C), which can provide protection from device performance degradation when applied to actual devices.

Hexagonal boron nitride (h-BN) is an attractive wide-bandgap material for application to emitters and detectors operating in the deep ultraviolet (DUV) spectral region. The optical transmittance of h-BN in the DUV region is particularly important for these devices. We report on the deposition of thick h-BN films (>200 nm) on Al0.7Ga0.3N templates via radio-frequency sputtering, along with the realization of ultrahigh transmittance in the DUV region. The fraction of the gas mixture (Ar/N2) was varied to investigate its effects on the optical transmittance of BN. DUV light transmittance of as high as 94% was achieved at 265 nm. This value could be further enhanced to exceed 98% by a post-annealing treatment at 800 °C in a N2 ambient for 20 min. The phase of the highly DUV–transparent BN film was determined to be a purely hexagonal structure via Raman spectra measurements. More importantly, these deposition processes were performed at a low temperature (300 °C), which can provide protection from device performance degradation when applied to actual devices.

Compound ceramic coatings with the main crystalline of Al2TiO5 (in the as-prepared coating without treatment) were prepared in situ on the surface Ti–6Al–4V alloy by means of pulsed bipolar micro-arc oxidation in NaAlO2 solution. For the purpose of studying the anti-oxidation properties of the samples, the coated samples treated in argon and the as-coated samples were calcined in air at 1000 °C. And the related characteristics were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray fluorescence (XRF) spectroscopy, respectively. The results show that, when it was calcined in air for 1 h, Al2TiO5 in the as-prepared coating decomposed and transformed into α-Al2O3 and rutile TiO2. However, after almost 4 h in argon, Al2TiO5 in the as-prepared coating decomposed and the final coating surface contents are completely α-Al2O3, and those of the middle interface are mainly Al2O3 and Ti2O3. The morphologies of the coatings after calcination in argon and air are different. High-temperature oxidation occurred violently in the alloy substrate without coatings. Furthermore, the weight gain curves of the as-prepared samples and the coated samples treated in argon both show a parabolic shape.

Background: Birch pollen sensitization and associated pollen-food syndrome among Chinese allergic patients have not been investigated. Methods: Sera from 203 allergic patients from the northern part of China and collected during February to July 2014 were investigated. Specific immunoglobulin E (IgE) against birch pollen extract Bet v and major birch pollen allergen Bet v 1 were measured using the ADVIA Centaur. The presence of major apple allergen Mal d 1 and soy bean allergen Gly m 4 specific IgE was measured by ImmunoCAP 100. Results: Among the 203 sera, 34 sera (16.7%) had specific IgE to Bet v and of these, 28 sera (82.4%) contained Bet v 1-specific IgE. Among the 28 sera with Bet v 1-specific IgE, 27 sera (96.4%) contained Mal d 1-specific IgE and 22 sera (78.6%) contained Gly m 4-specific IgE. Of the 34 Bet v-positive sera, 6 sera (17.6%) contained no specific IgE for Bet v 1, Mal d 1, or Gly m 4. Almost all Bet v-positive sera were donated during the birch pollen season. Conclusions: The prevalence of birch allergy among patients visiting health care during pollen season can be as high as 16.7% in Tangshan City. The majority of Chinese birch allergic patients are IgE-sensitized to the major birch pollen allergen Bet v 1 as well as to the major apple allergen Mal d 1 and soy bean allergen Gly m 4. A relatively high number of patients (17.6%) are IgE-sensitized to birch pollen allergen(s) other than Bet v 1. The high prevalence of specific IgE to Mal d 1 and Gly m 4 among Bet v 1-sensitized patients indicates that pollen-food allergy syndrome could be of clinical relevance in China.

The external quantum efficiency (EQE) in electrically injected AlGaN-based deep-ultraviolet light-emitting diodes (DUV-LEDs) is severely limited by their poor current injection efficiency (CIE). We report improvement in the CIE via controlling the relaxation of strains in the p-AlGaN hole injection layer (HIL) and the electron blocking layer (EBL). Simulation results show that an unrelaxed strain in the HIL associated with a relaxed strain in EBL can significantly enhance CIE. Deeper analysis indicates that high hole concentrations can be generated at HIL/EBL interface by strain-induced piezoelectric fields, which can then provide abundant numbers of holes for injection into quantum wells. Two sub-280 nm DUV-LEDs were fabricated with specific designs for different strain relaxations in the p-AlGaN HIL by changing the HIL thickness from 200 to 20 nm. The strain difference was identified using Raman spectroscopy. Electroluminescence measurements demonstrated much higher EQE in the strained-HIL DUV-LEDs. By separating the EQE contributions of three efficiencies, i.e. the CIE, the radiative recombination efficiency and the light extraction efficiency, we found that the EQE enhancement could mainly be attributed to the improved CIE, which agreed well with the simulation results.

By application of the theory of complex variable functions, dynamic propagation problems concerning symmetrical mode III interface crack of Aluminum alloys were investigated. The problems dealt with can be very facilely translated into Riemann-Hilbert problem by the approaches of self-similar functions, and the universal representations of analytical solutions of the stresses, displacements and dynamic stress intensity factors for the surfaces of symmetrical mode III interface crack subjected to motive increasing loadings Pt5/x5 and Px6/t5 were attained, respectively. After those solutions were utilized by superposition principle, the solutions of discretionally complicated problems could be easily acquired.

By the measures of the theory of complex variable functions, dynamic propagation problems of symmetrical mode III crack were researched. The problems considered can be very facilely translated into Riemann-Hilbert problem by means of self-similar functions, and the analytical solutions of the stress, the displacement and dynamic stress intensity factor under the conditions of motive variational loads Px/t and Pt3/x2 which were applied the surfaces of mode III crack, respectively, were acquired.

Compound ceramic coatings with the main crystal phase of Al2TiO5 (as-coated samples) were prepared in situ on the surface of Ti-6Al-4V alloy by means of pulsed bi-polar micro-arc oxidation (MAO) in an NaAlO2 solution. The coated samples were calcined in argon and air at 1000 oC, respectively. The phase composition, surface and section morphology, and element contents of the ceramic coatings were investigated by X-ray diffractometry(XRD), Scanning electron microscopy (SEM) and X-ray fluorescence spectroscopy (XRF). The samples were treated in argon and the as-coated ones were calcined in air at 1000 oC to study the anti-oxidation properties of the samples. The results show that Al2TiO5 had been decomposed in an hour and transformed into α-Al2O3 and rutile TiO2 in air. However, Al2TiO5 had been decomposed in four hours in argon and the final coating surface was completely composed of α-Al2O3. The content of Al2O3 was decreased from outside to inside layers and Ti2O3 was formed in the coating. Furthermore, the morphology of the ceramic coatings after the calcination was different. The coatings calcined in argon were finer; the grains and pores were smaller than those in air. The high oxidation reaction of the TC4 substrate was the fiercest and the weight gains of the coated samples treated in argon was the lowest. The weight gains of the ceramic coatings were nearly changing in the form of parabola law.

A ridge-shaped AlGaInP/GaInP quantum well (QW) structure with a ridge top width in the sub-wavelength region (500–600 nm) is successfully fabricated by selective area metal organic vapor phase epitaxial growth on patterned GaAs substrates, as the first step towards the realization of high-efficiency light-emitting diodes (LEDs) utilizing the evanescent wave coupling effect. It is confirmed by an X-ray diffraction study that AlGaInP layers grown on all the different facets of the ridge structure satisfy the lattice matching requirements for high-efficiency LED applications. A considerable enhancement of the light-extraction efficiency in the fabricated ridge-shaped QW structure is demonstrated by means of a photoluminescence analysis. The realization of the evanescent wave coupling effect is suggested by theoretical simulation. (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Compound ceramic coatings with the main crystal phase of Al2TiO5(as-coated samples) were prepared in situ on the surface of Ti-6Al-4V alloy by means of pulsed bi-polar micro-arc oxidation (MAO) in an NaAlO2solution. The coated samples were calcined in argon and air at 1000°C, respectively. The phase composition, surface and section morphology, and element contents of the ceramic coatings were investigated by X-ray diffractometry (XRD), Scanning electron microscopy (SEM) and X-ray fluorescence spectroscopy (XRF). The samples were treated in argon and the as-coated ones were calcined in air at 1000°C to study the anti-oxidation properties of the samples. The results show that Al2TiO5had been decomposed in an hour and transformed intoα-Al2O3and rutile TiO2in air. However, Al2TiO5had been decomposed in four hours in argon and the final coating surface was completely composed ofα-Al2O3. The content of Al2O3was decreased from outside to inside layers and Ti2O3was formed in the coating. Furthermore, the morphology of the ceramic coatings after the calcination was different. The coatings calcined in argon were finer; the grains and pores were smaller than those in air.

As a rule, when a crack happens in composite materials, the fibrous system will generate bridging fibers resulted in the asymmetrical extending of the crack. In this paper, a dynamic asymmetrical crack model of bridging fiber pull-out in unidirectional composite materials is built for analyzing the distributions stress and displacement with the internal asymmetrical crack under the loading conditions of an applied non-stress and the traction forces on crack faces yielded by the bridging fiber pull-out model. Thus the fiber failure is determined by the maximum tensile stress, the fiber ruptures, and hence the crack propagation should also occur in self-similar modality. The formulation involves the development of a Riemann-Hilbert problem. The analytical solution of an asymmetrical extension crack in unidirectional composite materials under the conditions of moving increasing loads Pt2/x2 and Px2/t is concluded, respectively. Based on relative material properties, the variable law of dynamic stress intensity factors was depicted perfectly. After the conclusion of analytical solutions with the superposition theorem, the solutions of arbitrary complex problems could be acquired.

Because of its large bandgap of ∼6.0 eV and suitability for high p-type doping, hexagonal boron nitride (h-BN) has become a candidate material that can serve as a p-layer by forming a heterostructure with AlGaN materials with a high Al fraction in deep-ultraviolet optoelectronic devices. The band offsets at the heterojunction are crucial to the device design because they determine the hole and electron transport properties across the heterojunction. In this study, we give the band alignment between h-BN and Al0.7Ga0.3N using the valence and conduction band offsets. The valence band offset of the h-BN/Al0.7Ga0.3N heterojunction is determined via X-ray photoelectron spectroscopy (XPS) to be as small as −0.01 ± 0.09 eV. The small valence band discontinuity that occurs at the h-BN/Al0.7Ga0.3N interface is further confirmed using angle-resolved valence band spectra from the XPS measurements. By combining the bandgap values of Al0.7Ga0.3N and h-BN which were estimated using absorption spectra measurements, the conduction band offset is found to be approximately 0.89 ± 0.09 eV. These results indicate that h-BN is an excellent material for hole injection into Al0.7Ga0.3N. Meanwhile, the electrons can be effectively blocked away from h-BN. These results will be helpful in the design of group-III-nitride-based optoelectronic devices, particularly deep-ultraviolet light-emitting diodes and lasers.

Using the effective-mass Hamiltonian for an arbitrary direction wurtzite semiconductor on the basis of k⋅p theory, we investigate the strain effects on the optical anisotropy in semi-polar and nonpolar GaN planes. The optical matrix elements are formulated for an arbitrary direction and calculated for the A- and R-planes. It is found that giant optical anisotropy appears in the A- and R-planes and the biaxial strain significantly changes the polarization properties.

Nanostructured surface layer was produced on Ti-6Al-4V alloy by surface mechanical attrition treatment(SMAT) technique, and the composite ceramic coatings of surface nanocrystallization/micro-arc oxidation(SNC/MAO) were prepared on the nanocrystallized surface of Ti-6Al-4V alloy by pulsed single-polar micro-arc oxidation in NaAlO2 solution. XRD, SEM and TEM techniques were used to investigate the phase and surface morphology of ceramic coatings and the influences on the surface state of the alloys. Meantime, the mechanical properties of Ti alloys were measured by tensile test. The results show that after the SMAT treatment for a short period of time, the surface layer was refined into ultrafine grains. The influences of the SMAT technique on the surface morphology of the ceramic coatings were also studied. The ceramic coatings are mainly composed of Al2TiO5, more compact and less porous than those untreated. The mechanical properties of Ti-6Al-4V alloy by SMAT technique are improved, compared with those untreated by SMAT technique.

Compound ceramic coatings with the main crystalline of Al2TiO5 (as-coated samples) were prepared in situ on the surface Ti-6Al-4V alloy by means of pulsed bi-polar micro-arc oxidation (MAO) in a NaAlO2 solution. The coated samples were calcined in argon and air at 1000 oC, respectively. The phase composition, surface morphology of the ceramic coatings were investigated by XRD, SEM and XRF. The samples were treated in argon and the as-coated ones were calcined in air at 1000 oC to study the anti-oxidation properties of the samples. The results show that Al2TiO5 was decomposed very soon and transformed into α-Al2O3 and rutile TiO2 in air. However, Al2TiO5 was decomposed very slowly in argon and the final coating surface was completely α-Al2O3. Also, the morphology of the ceramic coatings after the calcination was different. The coatings calcined in argon were fined; grains and pores were smaller than those in air. High temperature oxidation occurred very strongly in the TC4 substrate, the weight gains of the as-coated ceramic coatings and the treated ones in argon were nearly changing in the form of parabola, and the weight gains of the coated samples treated in argon were comparatively lower than those of the as-coated samples.

Compound ceramic coatings were prepared on Ti-6Al-4V allosy by pulsed bi-polar Micro-plasma Oxidation (MPO) in NaAlO2(S1) and Na2SiO3(S2) solution respectively. The coated samples were calcined in argon under 1000 oC. The phase composition,morphology and element content of the ceramic coatings were investigated by XRD, SEM and XRF. After oxidation in argon, The Al2TiO5 of S1 coating surface was decomposed into Al2O3. SiO2 was crystalized in S2 coating with the final proportion of SiO2 to TiO2 on the coating surface is 81:18. The morphology of the ceramic coatings after the calcination was also different. S1 coatings calcined in argon were fine, grains and pores were smaller and were combined tightly with the substrate, on the contrary, S2 coatings calcined in argon cracked on the coating surface and were separated with the substrate. The content of elements in the coatings both changed a little, which may be due to the reaction of the substrate in the oxidation. According to the phase composition and the morphology of the coatings, S1 coatings are better than S2 coatings.

The anodized TiO2 ceramic film was post-treated by photoreduction and ion sputtering, respectively, to deposit platinum on the surface of the films. Surface morphology, the main elements of the films and platinum distribution on the film surface were investigated by scanning electron microscopy and energy dispersive spectroscopy. The phase composition of the films was examined by X-ray diffraction. The photocatalytic activity was compared through the effect of the films on photocatalytic (PC) degradation rate of the humic acid. The results showed that both films were composed of Pt5Ti3, rutile (R) TiO2 and anatase (A) TiO2, and the content of TiO2 (R) of the film prepared by photoreduction was a little more than that of the film by ion sputtering. Compared with Pt on the Pt-TiO2 ceramic film by photoreduction, Pt on the Pt-TiO2 film by ion sputtering dispersed more evenly and the grains were much smaller. Pt particulates in the film post-treated by ion sputtering were more strongly combined with the film than those by photoreduction. Besides, the PC degradation rate of humic acid by both Pt-TiO2 films were higher than that by TiO2 film, and Pt-TiO2 film by ion sputtering had higher catalytic activity and longer using life than that by photoreduction.

We studied on various p-electrode patterns to solve current crowding problem in AlGaN-based deep-ultraviolet light-emitting diode. Simulation results of optimized p-electrode pattern showed a uniform current density distribution and improved performance of light output power.

Light extraction efficiency (LEE) in deep-ultraviolet light emitting diodes with AlN substrate was investigated using Ray Tracing method. The results showed that LEE was dramatically improved by optimizing the sidewalls angle and AlN thickness.

We thoroughly explored the physical origin of the efficiency decrease with increasing injection current and current crowding effect in 280 nm AlGaN-based flip-chip deep-ultraviolet (DUV) light-emitting diodes (LEDs). The current spreading length was experimentally determined to be much smaller in DUV LEDs than that in conventional InGaN-based visible LEDs. The severe self-heating caused by the low power conversion efficiency of DUV LEDs should be mainly responsible for the considerable decrease of efficiency when current crowding is present. The wall-plug efficiency of the DUV LEDs was markedly enhanced by using a well-designed p-electrode pattern to improve the current distribution.

We propose a method to determine the current injection efficiency (CIE) and internal quantum efficiency (IQE) of light-emitting diodes (LEDs) during current injection. The method is based on fourth-order polynomial fitting of a modified rate equation to electroluminescence data. Our method can extract the CIE at low injection current densities, unlike conventional methods that generally assume the CIE to be unity. We apply the method to AlGaN-based deep-ultraviolet LEDs. Results show that the CIE was only approximately 51% at low injection current densities and was almost independent of injection current density up to 100 A/cm2. The peak IQE was 77%.

Ceramic coatings with the main crystalline of TiO2 were prepared on Ti-6Al-4V alloy by pulsed bi-polar Micro-arc Oxidation (MAO) in Na2SiO3 solution. The coated samples were calcined in argon under 1000oC. The phase composition, morphology and element content of the ceramic coatings were investigated by XRD, SEM and EDS. The results showed that the main components of the coatings are TiO2 and amorphous substances, after oxidation in argon, SiO2 was crystalized in coating. The content of elements in the coatings both changed a little.

Nanostructured surface layer was produced on Ti-6Al-4V alloy by surface mechanical attrition treatment (SMAT) technique, and the composite ceramic coatings of surface nanocrystallization/ micro-arc oxidation (SNC/MAO) were prepared on the nanocrystallized surface of Ti-6Al-4V alloy by pulsed single-polar micro-arc oxidation in NaAlO2 solution. XRD, SEM and TEM techniques were used to investigate the phase and surface morphology of ceramic coatings and the influences on the surface state of the alloys. Meantime, the mechanical properties of Ti alloys were measured by tensile test. The results show that after the SMAT treatment for a short period of time, the surface layer was refined into ultrafine grains. The influences of the SMAT technique on the surface morphology of the ceramic coatings were also studied. The ceramic coatings are mainly composed of Al2TiO5, more compact and less porous than those untreated. The mechanical properties of Ti-6Al-4V alloy by SMAT technique are improved, compared with those untreated by SMAT technique.

Nanostructured surface layer was produced on the Ti-6Al-4V alloy by surface mechanical attrition treatment (SMAT) technique, and then the ceramic composite coatings of surface nanocrystallization/ micro-arc oxidation (SNC/MAO) were prepared on the nanocrystallized surface of Ti-6Al-4V alloy by pulsed single-polar micro-arc oxidation in NaAlO2 solution. The phase composition, morphology of surface and section and element content of the nanostructured surface layer and the ceramic coatings were investigated by XRD, TEM, SEM and EDS, respectively. The results showed that after the SMAT technique treatment for a short period of time, the surface layer was refined into ultrafine grains. The thickness of the coatings on the substrate treated by SMAT technique is about 10μm by micro-arc oxidation, which is thicker than the ones on the substrate untreated by SMAT technique, and the ceramic coatings are mainly composed of Al2TiO5. Besides, a bright interface layer comes out between the substrate and the coating when the substrate treated by SMAT technique. The influences of the SMAT technique on the surface morphology of the ceramic coatings also changed. The coatings using the SMAT technique were more compact and less porous than the ones on the substrate untreated by SMAT technique. The content of elements in the nanostructured surface layer on Ti-6Al-4V alloy had changed after the SMAT technique: the content of Ti increased, the content of V decreased, and the content of Al changed a little. The contents of Al and P in the coating increased while the content of Ti decreased.

Compound ceramic coatings with the main crystalline of Al2TiO5 (as-coated samples) were prepared on Ti-6Al-4V alloy by pulsed bi-polar micro-plasma oxidation (MPO) in NaAlO2 solution. The coated samples were calcined in Ar and air at 1000oC, respectively. The phase composition, morphology and element content of the coatings were investigated by XRD, SEM and XRF. The samples treated in Ar and the as-coated ones were calcined in air at 1000oC to study the oxidation resistance of the samples. The results showed that Al2TiO5 decomposed and transformed into corundum and rutile TiO2 during the high temperature calcination. Al2TiO5 decomposed very quickly in air and the proportion of Al2O3 to TiO2 was 44:55 after a complete decomposition. On the contrary, Al2TiO5 decomposed very slowly in argon with the final proportion of Al2O3 to TiO2 of 81:18 on the coating surface. The morphology of the ceramic coatings after the calcination was also different. The coatings calcined in argon were fined: the grains and pores were smaller than those of the coatings calcined in air. The weight gains of both coatings changed in the form of parabola law, and the weight gains of the coated samples treated in argon were comparatively lower than that of the as-coated samples. During the high temperature calcination, the samples treated in argon cannot distort easily, compared with the as-coated ones.

Objective: Weed pollens are common sources of allergens worldwide. The prevalence of weed pollen sensitization is not yet fully known in China. The purpose of this study was to investigate the prevalence of sensitization to weed allergens from Artemisia, Ambrosia, and Humulus in northern China. Methods: A total of 1 144 subjects (aged from 5 to 68 years) visiting our clinic from June to October 2011 underwent intradermal testing using a panel of 25 allergen sources. Subjects with positive skin responses to any pollen were further tested for their serum concentrations of IgE antibodies against Artemisia vulgaris, Ambrosia artemisiifolia, and Humulus scandens, and against the purified allergens, Art v 1 and Amb a 1. Results: Of 1 144 subjects, 170 had positive intradermal reactions to pollen and 144 donated serum for IgE testing. The prevalence of positive intradermal responses to pollens of Artemisia sieversiana, Artemisia annua, A. artemisiifolia, and H. scandens was 11.0%, 10.2%, 3.7%, and 6.6%, respectively. Among the intradermal positive subjects, the prevalence of specific IgE antigens to A. vulgaris was 58.3%, to A. artemisiifolia 14.7%, and to H. scandens 41.0%. The prevalence of specific IgE antigens to the allergen Art v 1 was 46.9%, and to Amb a 1 was 11.2%. The correlation between the presence of IgE antibodies specific to A. vulgaris and to the Art v 1 antigen was very high. Subjects with A. artemisiifolia specific IgE also had A. vulgaris specific IgE, but with relatively high levels of A. vulgaris IgE antibodies. There were no correlations between the presence of IgE antibodies to H. scandens and A. vulgaris or to H. scandens and A. artemisiifolia. Conclusions: The intradermal prevalence of weed pollen sensitization among allergic subjects in northern China is about 13.5%. Correlations of specific IgE antibodies suggest that pollen allergens from Artemisia and Humulus are independent sources for primary sensitization.

The current crowding is an especially severe issue in AlGaN-based deep-ultraviolet (DUV) light-emitting diodes (LEDs) because of the low conductivity of the n-AlGaN cladding layer that has a high Al fraction. We theoretically investigated the improvement in internal quantum efficiency and total resistances in DUV-LEDs with an emission wavelength of 265 nm by a well-designed p-electrode geometry to produce uniform current spreading. As a result, the wall-plug efficiency was enhanced by a factor of 60% at an injection current of 350 mA in the designed uniform-current-spreading p-electrode LED when compared with an LED with a conventional cross-bar p-electrode pattern.

We theoretically study the electronic structure, spin splitting, effective mass, and spin orientation of InAs nanowires with cylindrical symmetry in the presence of an external electric field and uniaxial stress. Using an eight-band k·p theoretical model, we deduce a formula for the spin splitting in the system, indicating that the spin splitting under uniaxial stress is a nonlinear function of the momentum and the electric field. The spin splitting can be described by a linear Rashba model when the wavevector and the electric field are sufficiently small. Our numeric results show that the uniaxial stress can modulate the spin splitting. With the increase of wavevector, the uniaxial tensile stress first restrains and then amplifies the spin splitting of the lowest electron state compared to the no strain case. The reverse is true under a compression. Moreover, strong spin splitting can be induced by compression when the top of the valence band is close to the bottom of the conductance band, and the spin orientations of the electron stay almost unchanged before the overlap of the two bands.

A novel light extraction technique based on coupling of evanescent waves in a ridge structure is reported. This technique can extract directly light outside the escape cone, which cannot be achieved with the conventional techniques.

We report an approach toward controlling the directionality of spontaneous emissions by employing the evanescent wave coupling effect in a subwavelength-sized ridge or truncated cone structure. An InGaAs/GaAs light-emitting diode in which a stripe-shaped InGaAs/GaAs quantum well with a stripe width of about 100 nm is embedded at the center of a subwavelength-sized GaAs ridge (of width ∼520 nm) is fabricated by micro processing and epitaxial regrowth techniques. Strong directionalities characterized by a half-intensity angle of 43° are observed in planes perpendicular to the ridge axis. The directionality is found to be almost independent of operating conditions.

We have investigated the three-dimensional emission patterns of GaAs/AlGaAs ridge structures with a sub-wavelength-sized top-flat facet by angle-resolved photoluminescence (PL). We found that the integrated PL intensity, and hence the light-extraction efficiency, can be enhanced by about 34% just by covering the ridge surface with a thin SiO2 layer. A double-coupling effect of evanescent waves that occurs at both the semiconductor-SiO2 and SiO2-air interfaces is suggested to be responsible for the improvement, based on a finite-difference time-domain simulation of the electromagnetic field around the ridge top.

Subwavelength-sized truncated cones satisfying the requirement for evanescent wave coupling effect at the emission wavelength were fabricated on the p-side of a GaN-based blue light-emitting diode (LED). The light-extraction efficiency increased by a factor of approximately 2.2 relative to that of a reference LED with a flat light-extraction surface. This light-extraction enhancement ratio is much larger than that realized by using conventional light-extraction techniques. The evanescent wave coupling effect appearing on the surface of the truncated-cone structure is believed to be the mechanism responsible for the large enhancement of light extraction.

Sub-wavelength-sized ridge structures that satisfy evanescent wave coupling effect requirements at the emission wavelength were fabricated through the photolithography and wet chemical etching of the light-extraction surface of a thin-film type AlGaInP light-emitting diode (LED). By doing this, the light output power relative to a reference LED with a flat light-extraction surface was increased by a factor of approximately 3.8, corresponding to an equivalent enhancement in light-extraction efficiency that is possibly attributable to an evanescent wave coupling effect occurring on the surfaces of the minute ridge structures.

The optical properties of a sub-wavelength-sized ridge-shaped AlGaInP/GaInP quantum well structure fabricated by selective-area metal organic vapor phase epitaxy are investigated. The ridge structure exhibits an 8.5 times stronger photoluminescence intensity at room temperature than a planar structure, corresponding to an enhancement of at least 13.6 times in the light extraction efficiency of the ridge sample with respect to the planar sample. Both emission pattern measurements and theoretical simulation demonstrate that the high light extraction efficiency originates from the evanescent wave coupling effect in a narrow ridge structure, which can directly extract the light outside the escape cones to air.

The optical properties of the strained wurtzite GaN are investigated theoretically within the nearest neighbor tight-binding method. The piezoelectric effect is also taken into account. The empirical rule has been used in the strained band-structure calculation. The results show that the excitonic transition energies are anisotropic in the c-plane in a high electronic concentration system and have a 60 degrees periodicity, which is in agreement with experiment. (C) 2008 American Institute of Physics. [DOI: 10.1063/1.3001937]