[Correlation between DCE-MRI quantitative perfusion histogram parameters, apparent diffusion coefficient and Ki-67 in different pathological types of lung cancer].

Objective: To explore the efficacy of dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) histogram molecular imaging index, apparent diffusion coefficient (ADC) in different types of lung cancer and explore their correlation with Ki-67. Methods: A total of 33 cases of lung cancer patients confirmed by pathology in Shaoxing People's Hospital from March 2017 to March 2018 were collected, 28 males and 5 females aged 50-85 years old, including 15 cases of squamous cell carcinoma, 12 cases of adenocarcinoma, and 6 cases of small cell carcinoma. All patients performed DCE-MRI and DWI imaging within one week before surgery or puncture. ADC values, DCE-MRI quantitative perfusion parameters by histogram metrics analysis (mean value, skewness, kurtosis, uniformity, entropy, energy, quantile) of K(trans), K(ep), V(e), and V(p) were then collected. Ki-67 expression in lung cancer tissue was detected by immunohistochemical method. One-way analysis of variance and least significant difference were used to compare the differences among the parameters of the three groups which were normal distribution and equal variances, while Kruskal-Walls test and Mann-Whitney U test were used to compare the parameters that did not conform to normal distribution or variance. Pearson correlation analysis was used to compare the correlations between quantitative perfusion histogram parameters, ADC values and immunohistochemical scores of Ki-67. Results: The Ki-67 count in small cell lung cancer(458±82, P=0.011) and squamous cell carcinoma(355±277, P=0.034)were significantly higher than that in adenocarcinoma (168±164). The correlation analysis showed that there was a significant negative correlation between ADC values and Ki-67 (P=0.018, r=-0.416). And V(e) (Q5, Q10) was negatively related to Ki-67 (P=0.017, r=-0.420; P=0.040, r=-0.366). In squamous cell carcinoma patients, V(e) (homogeneity) was significantly negatively correlated with the expression of Ki-67 (P=0.033, r=-0.570). K(trans)(homogeneity) and V(e) (homogeneity, Q5, Q10, Q25) were significantly positively correlated with ADC values (P value from 0.001 to 0.035, r value from 0.545 to 0.765). Conclusion: DCE-MRI quantitative perfusion histogram parameters, ADC value can evaluate the lung cancer cell proliferation activity in different pathological types.

[The correlation between the cell density of local advanced lung cancer tumor and the ADC value of 3.0 T MRI diffusion weighted imaging].

Objective: To investigate the correlation between tumorous cellular density (TCD) and apparent diffusion coefficient (ADC) of 3.0 T magnetic resonance diffusion weighted imaging (DWI) in local advanced lung cancer. Methods: From January 2015 to December 2017, a total of 59 patients with locally advanced lung cancer confirmed by pathology in Shaoxing People's Hospital who underwent DWI by 3.0 T magnetic resonance imaging were included.The ADC and TCD values of tumor were measured. The difference and correlation between ADC value and TCD in lung cancer were analyzed. Results: Among 59 lung cancer cases who were examined with DWI, 45 cases of TCD were obtained. Statistical analysis showed that the ADC value of small cell lung cancer (SCLC) was significantly higher than that of squamous cell carcinoma (P=0.011)and adenocarcinoma (P=0.004). TCD of small cell carcinoma was significantly higher than that of squamous cell carcinoma (P=0.007) and adenocarcinoma (P<0.01). There was no statistical difference in ADC value and TCD between squamous cell carcinoma and adenocarcinoma (all P>0.05). There was negative correlation between the ADC value and TCD in lung cancer (P=0.001, r=-0.534). Conclusions: DWI is not only beneficial to distinguish SCLC from squamous cell carcinoma and adenocarcinoma, but also can indirectly reflect the tumorous cellular density.It can provide a basis for monitoring the therapeutic effect of clinical lung cancer.

[Application on the quantitative perfusion parameters of dynamic contrast-enhanced MRI in the pathological subtype of uterine leiomyoma].

Objective: To analyze the value of the quantitative perfusion parameters of dynamic contrast-enhanced MRI(DCE-MRI) in the pathological subtype of uterine leiomyoma. Methods: A total of 35 cases of uterine leiomyoma confirmed by surgery and pathology were retrospectively analyzed in Shaoxing People's Hospital from October 2015 to May 2016.All cases underwent DCE-MRI. Quantitative perfusion parameters were prospectively measured and analyzed, including transfer constant (K(trans)) , efflux rate constant (K(ep)), extravascular extracellular space volume ratio (V(e)), blood plasma volume ratio (V(p)), permeability surface area product (PS) and plasma flow (F(p)) , using signal-input two-compartment tracer kinetic models (Extended Tofts model and Exchange model) in 35 leiomyoma cases.After the operation, the 35 cases were divided into three groups according to the pathological classfication , the ordinary, the cellular and the degeneration type.To analyze the differences among the three groups about the quantitative perfusion parameters of uterine leiomyoma. Compared with the gold standard of pathological findings, the ROC curves were drawn to evaluate the diagnostic efficacy of different quantitative perfusion parameters. Results: In the ordinary, cellular and degeneration type of uterine leiomyoma, K(trans) value were respectively(0.684±0.341), (1.897±0.458), (0.554±0.514)/min; K(ep) were respectively(1.004±0.685), (2.362±1.001), (1.274±1.093)/min; V(e) were respectively 0.789%±0.186%, 0.806%±0.203%, 0.537%±0.314%; V(p) were respectively 0.145%±0.196%, 0.502%±0.338%, 0.062%±0.106% and F(p) were respectively(0.792±0.461), (2.426±0.509), (0.628±0.551)ml/min.Among three groups, the value of K(trans), K(ep), V(e), V(p) and F(p) had statistical difference(all P<0.05), the value of PS didn't have statistical difference. The value of K(trans), K(ep), V(p) and F(p) in cellular type were higher than the ordinary type(all P<0.01); the value of K(trans), V(p) and F(p) in cellular type were higher than the degeneration type(all P<0.01); the value of V(e) in ordinary type was higher than the degeneration type(P<0.05). The area under ROC curve was 0.981 for K(trans), 0.904 for K(ep), 0.622 for V(e), 0.840 for V(p) and 0.994 for F(p). Conclusion: The quantitative perfusion parameters of DCE-MRI , especially the value of K(trans), K(ep), V(p) and F(p) have a great diagnostic efficacy in the pathological classfication of uterine leiomyoma which will become a predictive factor of pathological classfication in uterine leiomyoma.

[The protective effect of N-acetylcysteine on acute lung injury induced by PFIB inhalation].

Objective: To study the protective effect of N-acetylcysteine on acute lung injury induced by PFIB inhalation and its mechanism. Methods: Survival experiment: 48 male ICR (CD-1) mice were randomly divided into 4 groups, i. e., PFIB control group, NAC prevention group, NAC treatment group, and NAC prevention + treatment group, each group contains 12 animals. The mice of PFIB C group were exposed to PFIB without any treatment. The mice of NAC P group were exposed to PFIB 30min after NAC administration. The mice of NAC T group were exposed to PFIB 1h before NAC administration, The mice of NAC P+T group were administrated with NAC twice (30 min before and 1h after PFIB inhalation) . 150 mg/kg NAC was given by each time. The 7 days survival rate of mice after lethal dose PFIB exposure was observed. 18 male Wistar rats were randomly divided into 3 groups i.e., normal control group (N-C) , PFIB control group (PFIB-C) and NAC prevention group (NAC-P) , with each group contains 6 animals in the second experiment. The rats of N-C group received no treatment. The rats of NAC-P group and PFIB-C group were exposed to PFIB 30min after treatment of NAC (420 mg/Kg, i.p.) and saline, respectively. The respiratory functions of animals were tested before and 24 h after PFIB inhalation. The arterial blood gas was analyzed after rats were anesthetized 24 hours post sublethal dose PFIB exposure. Then samples of BALF, plasma and lung tissue were collected. Wet lung/body weight ratio, protein and phospholipid content in BALF, and T-SOD, GSH, GSH-Px in plasma and lung tissue were measured. The expression of Peroxiredoxin 2 was detected by Westernblot assay. Results: NAC prevention can significantly improve the survival of mice exposed to a lethal dose PFIB while NAC treatment is ineffective. Severe lung edema was observed in rats 24 h after PFIB exposure. Compared to N-C group, the wet lung/body weight ratio, protein and phospholipid content in BALF, and respiratory rate of PFIB control group all increased significantly (P<0.01) . The arterial oxygen partial pressure (PaO(2)) reduced significantly (P<0.05) . The GSH-Px activity in lung tissue reduced significantly (P<0.01) while the expression of Peroxiredoxin 2 increased significantly (P<0.01) . NAC prophylaxis significantly reduced the wet lung/body weight ratio, protein and phospholipid content in BALF, respiratory rate of rats exposed to PFIB (P<0.01) . Compared with PFIB-C group, the PaO(2) (P<0.05) and the activity of GSH-Px (P<0.01) and the expression of Peroxiredoxin 2 in lung tissue (P<0.01) were increased significantly. Conclusion: Acute lung injury induced by PFIB inhalation is related to oxidative stress caused by the stimulation to lung. induced and pulmonary subjected to stimulate the generation of exposure, NAC prevention can regulation of the redox system in lung tissue and protect target organ of the treated animals effectively.

STAT1 inhibitor alleviates spinal cord injury by decreasing apoptosis.

Spinal cord injury (SCI) is typically caused by trauma or disease, and it severely affects patients' motor function. The relationship between signal transducers and activators of transcription-1 (STAT1) and neuronal death after cerebral focal ischemia has been comprehensively studied, but its role in SCI remains largely unknown. This study investigated the protective effect of an STAT1 inhibitor on SCI. Thirty SD rats were SCI-induced and were then randomly divided into two groups (N = 15 each), either receiving STAT1 or the STAT1 inhibitor S1491 by intraperitoneal injection. The motor dysfunction of the rats was evaluated by behavioral scores, followed by the examination of SCI by hematoxylin and eosin staining. Apoptosis was also detected by Western blot and terminal deoxynucleotidyl transferase-mediated dUTP nick-end-labeling (TUNEL) assay. The motor functions of rats receiving STAT1 did not score as well as the STAT1 inhibitor group (P < 0.01). Further assays showed remarkable improvements in pathological damage to spinal code tissue in STAT1 inhibitor-treated rats, along with lower Bax and higher Bcl-2 expression. The STAT1 inhibitor also suppressed the occurrence of TUNEL-positive cells compared to the STAT1-treated group. In summary, we suggest that the STAT1 inhibitor alleviates SCI by decreasing apoptosis.

Genetic analysis of floral organ size in broccoli × cabbage via a mixed inheritance model of a major gene plus polygene.

Broccoli and cabbage are important vegetable crops that produce hybrid seeds after insect pollination; the size of floral organs is crucial for this process. To investigate the genetic characteristics of floral organ sizes (corolla width, petal length and width, and lengths of stamen, anther, style, and stigma) and to improve the flower size and breeding efficiency of broccoli, we used multi-generation analysis of a major gene plus polygene model. Six populations obtained from a broccoli inbred line 93219 (small floral organs) and cabbage inbred line 195 (large floral organs) were used for the analysis. Corolla and petal width and stamen and anther length were controlled by the additive-dominance-epistasis polygene model. The heritability of these traits in BC1, BC2, and F2 generations was high (72.80-93.76%). Petal and stigma length were governed by the two major genes of additive-dominance-epistasis effects plus additive-dominance polygene model; the major gene heritability in the F2 generation were 79.17 and 65.77%, respectively. Style length was controlled by one major gene of additive-dominance effects plus additive-dominance-epistasis polygene model; the major gene heritability in BC1, BC2, and F2 were 40.60, 10.35, and 38.44%, respectively; the polygene heritability varied from 41.85 to 68.44%. Our results provide important genetic information for breeding, which could guide improvement of flower-related traits and lay the foundation for quantitative trait loci mapping of the flower-size traits in Brassica.

[Clinical value of assisted laparoscopic ultrasonography in laparoscopic myomectomy].

Objective: To explore the application value of assisted laparoscopic ultrasound in myomectomy. Methods: One hundred and fifty six patients who underwent myomectomy in Beijing Obstetrics and Gynecology Hospital from 2011 to 2013 were enrolled.The patients were randomly divided into laparoscopic ultrasound guided group (n=57), laparoscopic group (n=54) and open resection group (n=45). The patients were followed up to calculate the residue and recurrence rates of uterine fibroids by vaginal ultrasound at 6th month and 12th-18th month after the operation. The residual and recurrence rates of the three methods were calculated and compared. Results: The recurrence rate of laparoscopic ultrasound guided group wassignificantly lower than that of laparoscopic group and open resection group (P<0.01) and (P<0.01). The residual rate of laparoscopic ultrasound guided group was also lower than that of laparoscopic group(P<0.05). However, there was no difference between the residual rates of laparoscopic ultrasound guided group and open resection group (P>0.05). When compared with open resection group, no difference was found in the residual and recurrence rates of laparoscopic group. The number of myoma was proportional to the residual rate and the recurrence rate. When the number of the myoma was more than 10, most of the cases existed residue. Conclusion: The application of assisted laparoscopic ultrasound in myomectomy couldreduce the residual and recurrence rate of uterine fibroids.

Inhibitory effect of berberine on human skin squamous cell carcinoma A431 cells.

Berberine (BBR) is a natural alkaloid with significant anti-tumor activity against many types of cancer cells. In this study, we investigated the molecular mechanisms employed by BBR to repress the proliferation and growth of skin squamous cell carcinoma A431 cells. Berberine was reported to inhibit the proliferation of A431 cells in a dose- and time-dependent manner and was observed to induce a series of biochemical events, including the loss of mitochondrial membrane potential, release of cytochrome-c to cytosol, induction of proteins of the Bcl-2 family and caspases, and the cleavage of poly(ADP)-ribose polymerase. This suggested its ability to induce apoptosis. The results of a wound healing test revealed that berberine inhibited the migration of A431 cells. Ezrin was transfected into A431 cells by RNA interference. The level of expression of Ezrin in the transfected A431 cells was observed to decrease with berberine treatment, which suggested that berberine might inhibit the invasion of A431 cells through Ezrin. The results of this study demonstrated that berberine could potentially inhibit proliferation, induce apoptosis, and inhibit the invasion of A431 cells.

Characterization of human umbilical cord mesenchymal stem cells following tissue mass culture.

The human umbilical cord represents a promising resource of mesenchymal stem cells (MSCs). In order to improve our understanding of MSCs derived from human umbilical cord (UC-MSCs), we isolated UC-MSCs from human umbilical cord tissues through a direct culture approach. We performed a comprehensive characterization of these cells based on analyses of morphology, growth features, cell surface antigen markers and differentiation capacity. All these analyses validated their stem cell nature. The UC-MSCs presented a spindle-shaped morphology and could be subcultured for up to 15 passages without losing their cellular features. Moreover, these UC-SMCs presented an expression profile of cell surface antigens similar to other MSCs: positive for CD44, CD90, and CD105 expression and negative for CD34, CD31, and CD45 expression. Differentiation assays further validated the multipotency of UC-MSCs by inducing these cells into osteoblasts, adipocytes and functional hepatocytes. Our studies clearly demonstrated that UC-MSCs resemble other types of MSCs in many aspects and have a great potential to be applied in tissue engineering and regenerative medicine.

Torasemide reduces dilated cardiomyopathy, complication of arrhythmia, and progression to heart failure.

The aim of this study was to analyze the incidence and types of arrhythmia and their relationship with the severity and prognosis of chronic heart failure (CHF) in patients with dilated cardiomyopathy (DCM), and to investigate the therapeutic effect of torasemide versus furosemide on CHF and incidence of arrhythmia. DCM patients with NYHA cardiac function II-IV were continuously monitored using a 24-h dynamic electrocardiogram (Holter), and arrhythmia incidence was analyzed by computer automatic analysis combined with manual assessment. In total, 125 participants were evenly divided into two groups: torasemide group which received 10 mg oral torasemide once daily) and regular anti-heart failure treatment (N=65), and furosemide group which received torasemide (20 mg once daily orally) and regular antiheart failure treatment (N=60). Another 60 normal healthy persons served as the normal control group. Incidence and severity of arrhythmia increased when degree of CHF was elevated. Size of left atrium was related to atrial fibrillation and size of left ventricle was related to malignant arrhythmia. At 3 months after treatment, cardiac function in both groups improved and incidence and severity of arrhythmia in both groups were reduced. However, left ventricular ejection fraction (LVEF) was higher in the torasemide group than in the furosemide group, while incidence of arrhythmia was lower in the torasemide group. Arrhythmias frequently occurred in patients with DCM and HF. Type of cardiac arrhythmia is closely related to ventricular enlargement and cardiac function grade. Torasemide is better for improving cardiac function to reduce arrhythmia and CHF compared to furosemide.

Experimental research on end-to-side anastomosis of peripheral nerves and effect of FK506 on end-to-side anastomosis.

OBJECTIVE: To study the effects of end-to-side anastomosis of initially-denatured nerves at different times. METHOD: 60 male Wistar albino rats were used to fabricate animal models for the experiment on end-to-side anastomosis of peripheral nerves and 50 female Wistar albino rats were used to fabricate animal models for the experiment on the effect of FK506 on end-to-side anastomosis. Bilateral common peroneal nerve, tibialis anterior muscle electrophysiological and histological examinations, tibialis anterior muscle wet muscle weight determination, and motor end plate examination were performed 3 months after operation. RESULTS: All recovery rates of action potential, single muscle contraction force and tetanic contraction force of the FK506 experimental group are significantly higher than those of the control group and the sectional area of muscle fiber is also higher than that of the control group of normal saline. CONCLUSION: The best time for end-to-side anastomosis of nerves should be controlled within 2 weeks and the effect of end-to-side anastomosis of nerves will gradually become unsatisfactory. FK506 plays a role in promoting functional rehabilitation following nerve end-to-side anastomosis (Tab. 7, Fig. 4, Ref. 31).

Discrete unified gas-kinetic wave-particle method for flows in all flow regimes.

This work proposes a discrete unified gas-kinetic wave-particle (DUGKWP) method for simulation of flows in all flow regimes. Unlike the discrete velocity method (DVM) and the direct simulation Monte Carlo (DSMC) method which solve the governing equations by either the deterministic method or the stochastic method, the DUGKWP combines the advantages of these two methods. In the DUGKWP, the information of microscopic particles as well as macroscopic flow variables are both evolved. Specifically, the microscopic particles are updated by the free-transport and resampling processes, while the macroscopic flow properties are evolved via solving the macroscopic governing equations of conservation laws with the finite volume method. According to the discrete characteristic solution to the Boltzmann-BGK equation utilized in the DUGKWP, in the highly rarefied flow regime, the motion of microscopic particles greatly determines the fluxes for the macroscopic governing equations. Conversely, for the continuum flow, no microscopic particle exists in the computational domain and the DUGKWP is degraded to the Navier-Stokes solver. Numerical studies validate that the DUGKWP can accurately predict the flow properties in all flow regimes. Furthermore, compared with the deterministic method, the DUGKWP enjoys superior efficiency with less memory consumption for both high-speed rarefied flows and flows close to the continuum regime.

Development of explicit formulations of G45-based gas kinetic scheme for simulation of continuum and rarefied flows.

In this work, the explicit formulations of the Grad's distribution function for the 45 moments (G45)-based gas kinetic scheme (GKS) are presented. Similar to the G13 function-based gas kinetic scheme (G13-GKS), G45-GKS simulates flows from the continuum regime to the rarefied regime by solving the macroscopic governing equations based on the conservation laws, which are widely used in conventional Navier-Stokes solver. These macroscopic governing equations are discretized by the finite volume method, where the numerical fluxes are evaluated by the local solution to the Boltzmann equation. The initial distribution function is reconstructed by the G45 distribution function, which is a higher order truncation of the Hermite expansion of distribution function compared with the G13 distribution function. Such high order truncation of Hermite expansion helps the present solver to achieve a better accuracy than G13-GKS. Moreover, the reconstruction of distribution function makes the development of explicit formulations of numerical fluxes feasible, and the evolution of the distribution function, which is the main reason why the discrete velocity method is expensive, is avoided. Several numerical experiments are performed to examine the accuracy of G45-GKS. Results show that the accuracy of the present solver for almost all flow problems is much better than G13-GKS. Moreover, some typical rarefied effects, such as the direction of heat flux without temperature gradients and thermal creep flow, can be well captured by the present solver.

[Prevalence of mountain-zoonotic type visceral leishmaniasis in Yangquan City of Shanxi Province from 2015 to 2020].

OBJECTIVE: To investigate the prevalence of mountain-type zoonotic visceral leishmaniasis (MT-ZVL) in Yangquan City, Shanxi Province from 2015 to 2020, so as to provide the scientific evidence for formulating the MT-ZVL control strategy. METHODS: The epidemiological data pertaining to MT-ZVL cases in Yangquan City from 2015 to 2020 were collected and descriptively analyzed. A Joinpoint regression model was created to analyze the trend in the MT-ZVL incidence in Yangquan City from 2015 to 2020 using annual percent change (APC). The sandflies surveillance data and the prevalence of Leishmania infections in dogs were collected in Yangquan City in 2020, and the regional distribution of sandflies density and sero-prevalence of Leishmania infections in dogs were calculated. In addition, the associations of sandflies density and sero-prevalence of Leishmania infections in dogs with the incidence of human MT-ZVL were examined using the linear correlation analysis. RESULTS: A total of 162 MT-ZVL cases were reported in Yangquan City, Shanxi Province from 2015 to 2020, with annual mean incidence of 1.9/105, and there were 4, 7, 16, 27, 33 cases and 75 cases with MT-ZVL reported from 2015 to 2020, appearing a tendency towards a rapid rise (APC = 72.79%, t = 11.10, P < 0.01). MT-ZVL cases were reported across the five counties (districts) of Yangquan City, and the cases predominantly occurred in Jiaoqu District (35.2%, 57/162) and Pingding County (33.3%, 54/162). MT-ZVL cases were predominantly detected in residents at ages of 15 years and older (71.6%, 116/162) and at ages of 0 to 2 years (22.2%, 36/162), with farmers (37.4%, 61/162) and diaspora children (24.5%, 40/162) as predominant occupations. The mean density of Phlebotomus chinensis was 6.3 sandflies per trap per night in Yangquan City from during the period from May to September, 2020, with the highest density observed in Jiaoqu District (12.6 sandflies per trap per night) and the lowest in Yuxian County (1.1 sandflies per trap per night), and there was a region-specific mean density of Ph. chinensis in Yangquan City (H = 17.282, P < 0.01). The sero-prevalence of serum anti-Leishmania antibody was 7.4% (2 996/40 573) in domestic dogs in Yangquan City, with the highest sero-prevalence seen in Jiaoqu District (16.6%, 1 444/8 677), and the lowest in Yuxian County (2.3%, 266/11 501), and there was a region-specific sero-prevalence rate of anti-Leishmania antibody in domestic dogs in Yangquan City (χ2 = 1 753.74, P < 0.01). The sero-prevalence of anti-Leishmania antibody was significantly higher in stray dogs (20.0%, 159/794) than in domestic dogs (χ2 = 176.63, P < 0.01). In addition, there were significant associations among the sandflies density, sero-prevalence of anti-Leishmania antibody in domestic dogs and the incidence of human MT-ZVL (r = 0.832 to 0.870, all P values < 0.05). CONCLUSIONS: The prevalence of MT-ZVL appeared a tendency towards a rapid rise in Yangquan City from 2015 to 2020, and systematic interventions are urgently needed for MT-ZVL control.

[First report of invasive Pomacea snails in Shandong Province].

OBJECTIVE: To characterize the species of invasive Pomacea snails that were discovered for the first time in Shandong Province. METHODS: Pomacea snails samples were collected in the field of Jining City, Shandong Province on October 2021 for morphological identification. Pomacea snails were randomly sampled and genomic DNA was extracted from foot muscle tissues of Pomacea snails for multiplex PCR amplification. The PCR amplification product was sequenced. Then, the sequence was aligned and a phylogenetic tree was created using the software MegAlign 7.1.0. In addition, Angiostongylus cantonensis infection was detected in Pomacea snails with the lung microscopy. RESULTS: A total of 104 living Pomacea snails were collected, and all were characterized as Pomacea spp. based on morphological features. Of 12 randomly selected adult Pomacea snails, multiplex PCR assay and sequencing identified eleven snails as P. canaliculata and one as P. maculata. No A. cantonensis infection was detected in 104 Pomacea snails. CONCLUSIONS: This is the first report of invasive Pomacea snails in Shandong Province, where P. canaliculata and P. maculata are found.

Metamorphic In(0.20)Ga(0.80)As p-i-n photodetectors grown on GaAs substrates for near infrared applications.

The growth and performance of top-illuminated metamorphic In(0.20)Ga(0.80)As p-i-n photodetectors grown on GaAs substrates using a step-graded In(x)Ga(1-x)As buffer is reported. The p-i-n photodetectors display a low room-temperature reverse bias dark current density of ~1.4×10(-7) A/cm(2) at -2 V. Responsivity and specific detectivity values of 0.72 A/W, 2.3×10(12) cm·Hz(1/2)/W and 0.69 A/W, 2.2×10(12) cm·Hz(1/2)/W are achieved for Yb:YAG (1030 nm) and Nd:YAG (1064 nm) laser wavelengths at -2 V, respectively. A high theoretical bandwidth-responsivity product of 0.21 GHz·A/W was estimated at 1064 nm. Device performance metrics for these GaAs substrate-based detectors compare favorably with those based on InP technology due to the close tuning of the detector bandgap to the target wavelengths, despite the presence of a residual threading dislocation density. This work demonstrates the great potential for high performance metamorphic near-infrared InGaAs detectors with optimally tuned bandgaps, which can be grown on GaAs substrates, for a wide variety of applications.

Efficient high-order radial basis-function-based differential quadrature-finite volume method for incompressible flows on unstructured grids.

This paper presents an efficient high-order radial basis-function-based differential quadrature-finite volume method for incompressible flows on unstructured grids. In this method, a high-order polynomial based on the Taylor series expansion is applied within each control cell to approximate the solution. The derivatives in the Taylor series expansion are approximated by the mesh-free radial basis-function-based differential quadrature method. The recently proposed lattice Boltzmann flux solver is applied to simultaneously evaluate the inviscid and viscous fluxes at the cell interface by the local solution of the lattice Boltzmann equation. In the present high-order method, a premultiplied coefficient matrix appears in the time-dependent term, reflecting the implicit nature. The implicit time-marching techniques, i.e., the lower-upper symmetric Gauss-Seidel and the explicit first stage, singly diagonally implicit Runge-Kutta schemes, are incorporated to efficiently solve the resultant ordinary differential equations. Several numerical examples are tested to validate the accuracy, efficiency, and robustness of the present method on unstructured grids. Compared with the k-exact method, the present method enjoys higher accuracy and better computational efficiency.

Variant of gas kinetic flux solver for flows beyond Navier-Stokes level.

In this paper, a variant of gas kinetic flux solver (GKFS) is presented for simulation of flows beyond the Navier-Stokes (NS) level. The method retains the framework of GKFS and reconstructs the numerical fluxes by the moments of distribution function at the cell interface, which is given from the local solution of the Boltzmann equation. In the conventional GKFS, the first-order Chapman-Enskog (CE) expansion is utilized to approximate the initial distribution function. By using the differential chain rule, it was found that the CE expansion form could be linked to the stress tensor and the heat flux. For flows in the NS level, the stress tensor and heat flux can be simply calculated from the linearized constitutive relationship and Fourier's law, respectively. However, for flows beyond the NS level, due to the strong nonequilibrium effect, the linearized constitutive relationship and Fourier's law are insufficient to predict the stress tensor and the heat flux. To overcome this difficulty, this paper introduces correction terms to the stress tensor and heat flux in the initial distribution function. These correction terms will take effect in the strong nonequilibrium region for flows beyond the NS level. To avoid finding complex expressions or solving complicated partial differential equations for the correction terms, a simple and iterative procedure is proposed to update the correction terms based on the framework of GKFS. The proposed method is validated by three benchmark cases which cover the flow from the continuum regime to the transition regime. Numerical results show that the present solver can provide accurate solution in the continuum regime. It is indeed the correction terms that take effect in the strong nonequilibrium region for flows beyond the NS level, which enables the present solver to capture the nonequilibrium phenomenon with reasonable accuracy for rarefied flows at moderate Knudsen number.