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The three transition metal atoms in the ground state structures of Ni2TiO2(CO)2–4− form a quasi-line. The extra electron is enriched on O attached to Ti. There has strong interaction between Ti and O.

Anisotropies exist in many sedimentary rocks, particularly in naturally fractured reservoirs, causing horizontal stress anisotropies. Case studies indicate that when a rock formation contains high dip-angle fractures or contains horizontal factures (e.g. bedding planes), it has very distinguished horizontal stresses. In these cases, the conventional isotropic method for estimating horizontal stresses may give erroneous results. Using the theory of anisotropy, horizontal stresses in the vertical transverse isotropy (VTI) and horizontal transverse isotropy (HTI) models are derived for determining in situ stresses in naturally fractured rocks. Comparing with the isotropic model, the VTI model predicts a higher minimum or maximum horizontal stress, which is suitable for shales. In contrast, the HTI model gives a lower minimum stress than the isotropic model. A combined model based on the VTI and HTI models is proposed for estimating the minimum horizontal stress in a naturally fractured formation containing natural fractures with different dip angles. Measured data in the Xujiahe gas reservoir in China reveal that the minimum horizontal stresses and formation breakdown pressures decrease as the fracture dip angles increase, which is consistent to the derived HTI model. Natural fractures can result in a decrease of the minimum horizontal stress by up to 3 MPa/km and a reduction of the formation breakdown pressure by up to 10 MPa/km in the studied area. Combining the proposed anisotropic model to the measured data of natural fractures and horizontal stresses, the assessment of in situ stresses and their impact on hydraulic fracturing are proposed. Case study demonstrates that the proposed model gives a good prediction of the minimum horizontal stresses in the naturally fractured reservoir.

To explore the diagnostic value of contrast-enhanced ultrasound (CEUS) enhancement patterns for differentiating solid pancreatic lesions and compare them with conventional ultrasound (US) and enhanced computed tomography (CT).A total of 210 patients with solid pancreatic lesions who had definite pathological or clinical diagnoses were enrolled. Six CEUS enhancement patterns were proposed for solid pancreatic lesions. Two US doctors blindly observed the CEUS patterns of solid pancreatic lesions and the interrater agreement was analyzed. The diagnostic value of CEUS enhancement patterns for differentiating solid pancreatic lesions was evaluated, and the diagnostic accuracy was compared with that of US and enhanced CT.There was good concordance for six CEUS enhancement patterns of solid pancreatic lesions between the two doctors, with a kappa value of 0.767. Hypo-enhancement (Hypo-E) or centripetal enhancement (Centri-E) as the diagnostic criteria for pancreatic carcinoma had an accuracy of 87.62%; hyper-enhancement (Hyper-E) for neuroendocrine tumors had an accuracy of 92.89%; capsular enhancement with low or uneven enhancement inside the tumor (Capsular-E) for solid pseudopapillary tumors had an accuracy of 97.63%; and iso-enhancement (Iso-E) or iso-enhancement with focal hypo-enhancement (Iso-fhypo-E) for focal pancreatitis had an accuracy of 89.10%. The diagnostic accuracy of CEUS was significantly different from that of US for 210 cases of solid pancreatic lesions (p 0.05) and was not significantly different from that of enhanced CT for 146 cases of solid pancreatic lesions (p 0.05).The different enhancement patterns of solid pancreatic lesions on CEUS were clinically valuable for differentiation.• Six CEUS enhancement (E) patterns, including Hyper-E, Iso-E, Iso-fhypo-E, Hypo-E, Centri-E, and Capsular-E, are proposed for the characterization of solid pancreatic lesions. • Using Hypo-E or Centri-E as the diagnostic criteria for pancreatic carcinoma, Hyper-E for neuroendocrine tumors, Capsular-E for solid pseudopapillary tumors, and Iso-E or Iso-fhypo-E for focal pancreatitis on CEUS had relatively high diagnostic accuracy. • The diagnostic accuracy of CEUS was greatly increased over that of US and was not different from that of enhanced CT.

Urban forest soil is often disturbed by rapid urbanization. Organic mulching is effective for improving soil quality and aggregate stability. This study evaluated how soil binding agents changed aggregate stability through organic mulching in urban forest soils. Three treatments were applied in Jiufeng National Forest Park, Beijing: (1) no organic mulch (control); (2) wood chips alone (5 cm thickness); and, (3) wood chips + wood compost (This mulch was divided into two layers, the upper layer of wood chips (2.5 cm), the lower layer wood compost (2.5 cm)). Soil samples were collected from the surface 10- cm soil layer and fraction into four aggregates. Glomalin-related soil protein and soil organic carbon were measured in bulk soil and the four aggregates. The results show that wood chips + wood compost increased the proportion of large and small macroaggregates, mean weight diameter and geometric mean diameter. The total and easily extractable glomalin-related soil protein were higher in the wood chips + wood compost. However, soil organic carbon was lower in the wood chips alone application compared to the controls and wood chips + wood compost. Easily extractable / total glomalin-related soil protein and glomalin-related soil protein / soil organic carbon ratios of wood chips alone and wood chips + wood compost had increased trend compared to the controls but did not reach significant levels (p > 0.05). Mean weight diameter and geometric mean diameter correlated positively with total and easily extractable glomalin-related soil protein but were not positively correlated with soil organic carbon, the ratios of easily extractable and total glomalin-related soil protein, and the ratios of glomalin-related soil protein and soil organic carbon. Redundancy analysis revealed that total glomalin-related soil protein was the most important driver for soil aggregate stability, especially the total glomalin-related soil protein of small macroaggregates. The results suggest that wood chips + wood compost enhanced soil aggregate stability through the increase of glomalin-related soil protein. Wood chips alone cannot enhance soil aggregate stability in urban forests in the short term.

BACKGROUND: Distinguishing aggressive pT1 papillary thyroid carcinomas (PTCs) from indolent PTCs before or during surgery is important. To the best of our knowledge, few reports in the literature have examined the value of the cytomorphologic features of PTC as predictors of aggressiveness. METHODS: This retrospective study included 226 pT1 PTC patients who underwent preoperative fine-needle aspiration cytology (FNAC) and surgery at Peking University Cancer Hospital between January 2018 and December 2019. Data on the clinical characteristics and pathological results were obtained from the electronic medical record database. All FNAC smears were blindly reviewed by two independent cytopathologists, and the associations between nine cytomorphologic features (lymphocytes, multinucleated giant cells, cellularity, cellular adhesiveness, nuclear size, nuclear pleomorphism, nuclear membrane regularity, intranuclear pseudoinclusions and the amount of cytoplasm) and clinicopathological parameters were statistically analyzed. RESULTS: Univariate analysis showed that cellularity, intranuclear pseudoinclusions, cellular adhesiveness, nuclear size, and nuclear pleomorphism were strong predictors of some clinicopathological parameters such as extracapsular invasion (ECI) and lymph node metastasis (LNM). Multivariate analysis confirmed that cellular adhesiveness was a strong independent predictor of ECI (P=0.001) and LNM (P

To compare the diagnostic efficacy of SonoVue and Sonazoid contrast enhanced ultrasound (CEUS) in correctly detecting and characterizing colorectal liver metastasis (CRLM) after chemotherapy.Patients with CRLMs treated with chemotherapy and subsequently scheduled for hepatic resection were prospectively enrolled from April 2020 to January 2021. Lesions detected by SonoVue or Sonazoid CEUS were recorded as and characterized as metastases or non-metastatic lesions respectively. Histopathology or intraoperative ultrasound with MRI were the reference standard.A total of 348 focal liver lesions in 42 patients were investigated, including 297 CRLMs and 51 non-metastatic lesions. SonoVue showed significantly higher diagnostic accuracy (64.7% versus 54.0%; P .001) and sensitivity (63.3% versus 50.5%; P .001) in the diagnosis of CRLMs than Sonazoid, both methods presented with similar specificity (72.5% versus 74.5%; P = 1.0). Forty metastases appeared non-hypoenhancing (hyperenhancing or isoenhancing) in the late phase and postvascular phase of Sonazoid CEUS and were mischaracterized as benign lesions.SonoVue performed significantly better than Sonazoid in the diagnosis of CRLMs after chemotherapy.

Objective To evaluate the diagnostic utility of The Bethesda System for Reporting Thyroid Cytology (TBSRTC) at Peking University Cancer Hospital, the incidence of noninvasive follicular thyroid neoplasms with papillary-like nuclear features (NIFTP), and the impact of reclassification on cytopathological outcomes. Methods We performed a retrospective study of thyroid fine-needle aspiration (FNA) cases between April 2014 and March 2019. The FNA results were classified according to TBSRTC. Post-surgery histological findings were followed up. Results A total of 2,781 thyroid FNAs were performed. The incidences of the 6 diagnostic categories (DCs I-VI) were 14.8%, 17.1%, 15.8%, 2.3%, 11.6% and 38.5%, respectively. A total of 1,122 patients (40.3%) had corresponding histological results. NIFTP accounted for 0.4% of papillary thyroid carcinoma (PTC) cases, and there was no significant difference in the risk of malignancy (ROM) for each TBSRTC DC between "NIFTP=carcinoma (Ca)" and "NIFTP≠Ca". When "NIFTP=Ca", the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of TBSRTC were 98.0%, 84.0%, 99.4%, 58.3%, and 97.5%, respectively. When "NIFTP≠Ca", the sensitivity, specificity, PPV, NPV and accuracy of the TBSRTC were 98.1%, 81.5%, 99.3%, 61.1%, and 97.5%, respectively. Conclusions TBSRTC is effective in the preoperative diagnosis of thyroid nodules in Peking University Cancer Hospital. The impact of the reclassification of NIFTP on cytopathological outcomes is limited because of its low incidence, and the revised ROMs are not suitable for Asian patients.

Atmospheric-pressure dielectric barrier discharge (DBD) with airflow participation has been widely used in recent years. In this experimental study, a diffuse DBD excited by repetitive nanosecond pulses is achieved in airflow. Upon the introduction of airflow to the gas gap, the discharge state transforms from a filamentary one into a diffuse one at first, followed by the generation of a thin filamentary discharge (TFD) at a high airflow rate. It is observed that the diffuse discharge (DD) and the TFD are ignited from the electrode boundary, which subsequently move toward the downstream region with a velocity below the corresponding airflow rate. Subsequent to hundreds of pulse cycles, a stationary discharge state is formed with the TFD in the upstream region and the DD in the downstream region. The length of the TFD region is associated with the airflow rate, the pulse repetition frequency (PRF), and the applied voltage. The observations presented above are ascribed to the transverse electric field at the electrode boundary and the redistribution of charges under the action of airflow.

The goal of the study described here was to investigate the value of shear wave elastography (SWE) in pre-operative staging of rectal cancer. Fifty-five patients with rectal cancer underwent pre-operative conventional endorectal ultrasonography (ERUS), SWE and enhanced magnetic resonance imaging (MRI) examinations. Pathologic results were used as the gold standard for cancer staging. The concordance rate with pathologic stage by ERUS and MRI and the stiffness values measured by SWE for tumors in different stages were compared. The concordance rates for cancer staging were 72.7% and 70.9% for conventional ERUS and enhanced MRI, respectively; the difference was not significant (p0.05). SWE indicated that the mean and maximum stiffness values of the tumors increased with advance in stage. The differences in stiffness values between T1 and T2, T1 and T3-4, as well as T2 and T3-4, were all statistically significant (p0.001). When the maximum stiffness values of 65.0 and 90.7 kPa are used for the diagnosis of T1, T2 and local advanced rectal cancer, the concordance rate of cancer staging was 85.5%, which was slightly higher than those of ERUS and MRI, although the difference was not statistically significant (p0.05). SWE is useful in judging the depth of invasion of rectal tumors. The value of tumor stiffness can provide a quantifiable indicator for pre-operative diagnosis of cancer staging and can be used as a supplement to conventional ERUS. Further studies with larger sample sizes are needed.

The routing protocol for low-power and lossy networks (RPL) has become the standard routing protocol for the Internet of things (IoT). This paper studies the application of RPL in the 6LoWPAN. In the topology construction process of the existing R_RPL routing strategy, the problem of the network depth of the node is not considered. This paper proposes an objective function optimization scheme named RR_RPL that combines energy consumption, hop count, ETX, and other metric factors and sets different weights for the parent nodes of different energy consumption. Simulations are done using Cooja with random waypoint mobility scenario, and the results show that the RR_RPL has higher network lifetime and PDR compared to related existing protocols.

OBJECTIVE The aim of this study was to evaluate the value of arrival-time parametric imaging for differential diagnosis of superficial enlarged lymph nodes. METHODS Patients with lymphadenopathy who received contrast-enhanced ultrasonography (CEUS) and biopsy were included in this study. Following CEUS, a prototype software of the arrival-time parametric imaging system was used to analyze the video footage. Arrival-time patterns during the arterial phase were evaluated. The quantitative parameters including arrival time of periphery, arrival time of center, and the travel time (△T) were calculated. RESULTS A total of 145 lymph nodes were analyzed. Arrival-time parametric imaging showed that 80.3% of metastatic lymph nodes and 68.4% of lymphoid tuberculosis presented a centripetal perfusion pattern, 76.5% of lymphoma showed complete homogeneous enhancement, and 81.2% of reactive lymph nodes had centrifugal patterns. The arrival time of periphery (sec) of metastatic lymph nodes was substantially earlier than that of lymphoma (11.0 ± 3.1 versus 12.6 ± 3.6; P

Objectives To retrospectively summarize the similarities and differences in contrast-enhanced ultrasound (US) findings for lymph node metastasis from adenocarcinoma, squamous carcinoma, and small cell lung cancer. Methods Patients who had received contrast-enhanced US examinations and had a histologic diagnosis of supraclavicular lymph node metastasis from lung cancer were included. The perfusion patterns on contrast-enhanced US images and time-intensity curve parameters were analyzed for the different pathologic types. The microvascular density and microvascular diameter were evaluated. Results Totally, 61 patients were enrolled in this study, including 26 cases with lung squamous carcinoma, 26 with lung adenocarcinoma, and 9 with small cell lung cancer. Contrast-enhanced US perfusion showed no significant differences in enhancement uniformity during the arterial phase and in the presence of unenhanced areas of metastatic lymph nodes with the 3 different pathologic origins (P > .05), but fewer unenhanced areas could be seen in metastatic lymph nodes from adenocarcinoma. The analysis of the time-intensity curve parameters showed that there were significant differences in the peak intensity between metastatic lymph nodes from lung squamous carcinoma and lung adenocarcinoma (P

Objectives We explored the clinical value of using contrast-enhanced ultrasound (US) enhancement patterns for the differential diagnosis of focal pancreatitis from pancreatic carcinoma. Methods A total of 136 solid pancreatic lesions with final diagnoses from January 2010 to February 2016 were enrolled in this study. Twenty-five cases were focal pancreatitis; 86 cases were pancreatic carcinoma; and 25 cases were other types. All of the patients received conventional and contrast-enhanced US examinations. Two experienced US physicians analyzed the contrast-enhanced US enhancement patterns and made diagnoses according to the conventional and contrast-enhanced US manifestations. The inter-rater agreement for the contrast enhancement patterns between the readers was analyzed. The diagnostic efficiency of contrast enhancement patterns for differentiating focal pancreatitis from pancreatic carcinoma was analyzed and compared with that of conventional US. Results The κ test showed good concordance for contrast enhancement patterns between the readers (P

OBJECTIVES To evaluate the diagnostic value of contrast-enhanced ultrasonography (CEUS) in the differential diagnosis of tuberculous and metastatic lymph nodes. METHODS Nineteen cervical tuberculous lymph nodes and 43 cervical metastatic lymph nodes were investigated. The CEUS perfusion patterns and parameters of time-intensity curve (TIC) were analyzed. Diagnostic accuracy and consistency of two physicians were compared before and after CEUS and TIC analysis. RESULTS Conventional ultrasonography showed no significant differences between tuberculous and metastatic lymph nodes. Concentric enhancement at the arterial phase of CEUS occurred in 15 of 19 (78.9%) tuberculous lymph nodes and 42 of 43 (97.7%) metastatic lymph nodes (P

A random poly(L-alanine-co-L-lactic acid) (PAL) with excellent thermo-sensitivity and no cytotoxicity was synthesized by the structure-controlled polycondensation from natural L-alanine and L-lactic acid. Only those PALs in which the contents of L-alanine structural unit are rigidly controlled in the smaller range of 53–65% show a reversible lower critical solution temperature of 35–60°C. The change of secondary structure in poly(L-alanine) segments by the introduction of L-lactic acid structural unit plays a decisive role in regulating the thermo-sensitivity of PAL. The viability of HeLa cells exposed to PAL reaches up to 91–116% after incubation of 24 and 72 h, indicating no cytotoxicity. Furthermore, PAL can easily form curcumin-loaded nano-carriers through its thermo-sensitivity and self-assembly. The curcumin-loaded PAL nano-particles are observed to clearly internalize into the cells by confocal laser-scanning microscopy, and thus can be used as a potential nano-drug-carrier.

In order to solve the problems of high handover delay, loss of interest packets and reduction of content hit rate caused by producer movement in naming data networks, a method of NDN Producer Regional Content Synchronization (NPRCS) based on ChronoSync protocol was proposed. In this method, the content of producers is synchronized to the cache of neighboring nodes in the process of producer movement to improve the availability of content after producer movement. Simulation results show that compared with the operating mechanism of NDN, the NPRCS method reduces the handover delay and retrieval time, and improves the consumer hit rate.

The congestion control algorithm of the named data network is not accurate in obtaining the congestion status, and the research is not carried out in time, and a congestion control strategy based on the fuzzy comprehensive evaluation algorithm is proposed. This strategy uses the fuzzy comprehensive evaluation algorithm to calculate and analyze the above two network parameters to obtain the network congestion state by detecting the buffer queue length of the network intermediate node and the actual and predicted round-trip time ratio. In order to refine the degree of network congestion, a variety of congestion is designed. The feedback signal uses the existing NACK feedback mechanism of the NDN network to send a congestion signal to the downstream node, and the downstream node adaptively adjusts the interest packet sending rate according to the congestion signal to achieve the purpose of reducing network congestion. In the NDN-SIM simulator, this algorithm is compared and analyzed with mainstream algorithms, and it is confirmed that this strategy can make full use of network resources and has higher transmission efficiency.

Very large-scale gap distances of atmospheric pressure dielectric barrier discharge (DBD) in glow mode are obtained through semiconductor materials. The maximum value of the gap distance is up to 70 mm. Based on the feature of the cathode sheath, Auger neutralization theory, the trapped electron and the accumulated charge in the DBD system, the secondary electron emission is one of the primary reasons for very large-scale gap distances of the DBD to produce glow discharge. Furthermore, the contribution of the effective capacitance, the gas voltage and the discharge power are also discussed. Significant for the research are the development and the practical applications of atmospheric pressure glow discharge in the DBD with very large-scale gap distances.

Motion segmentation plays an important role in many vision applications, yet it is still a challenging problem in complex scenes. The typical conditions in real world scenarios like illumination variations, dynamic backgrounds and camera shaking make negative effects on segmentation performance. In this paper, a newly designed method for robust motion segmentation is proposed, which is mainly composed of two interrelated models. One is a normal random model(N-model), and the other is called enhanced random model(E-model). They are constructed and updated in spatio-temporal information for adapting to illumination changes and dynamic backgrounds, and operate in an Ada- Boost-like strategy. The exhaustive experimental evaluations on complex scenes demonstrate that the proposed method outperforms the state-of-the-art methods.

The continuous use of nonsteroidal anti-inflammatory drugs such as ibuprofen frequently leads to some serious side-effects including stomach ulcers and bleeding. In this paper, two kinds of new biocompatible polyesters (PIGB, PIGH) and polyester-amide (PIGA) comprising biodegradable components (L-glutamic acid,1,4-butanediol, and1,6-hexanediol and6-amino hexanol) and ibuprofen as pendant group have been prepared by the melting polycondensation. The chemical structures of the monomer and polymers are characterized by FTIR,1H NMR spectrum, GPC, and contact angle measurements. The drug loading of ibuprofen reaches very high level (35–37%) for PIGB, PIGH, and PIGA carriers. The free ibuprofen molecules are releasedin vitrofrom polymer carriers in a controlled manner without a burst release, different from the release pattern observed in the other drug-encapsulated systems. It is also found that the different hydrophilicity among PIGB, PIGH, and PIGA plays a key role in the time-controlled release of ibuprofen. In addition, the viability of HeLa cells after 48 h of incubation reaches more than 100%, indicating no cytotoxicity for PIGB, PIGH, and PIGA carriers.

OBJECTIVES To investigate the application of contrast-enhanced sonography compared with conventional sonography and contrast-enhanced computed tomography (CT) for diagnosis of space-occupying lesions in the extrahepatic bile duct. METHODS Seventy-two patients with pathologic diagnoses of space-occupying lesions in the extrahepatic bile duct were retrospectively recruited. All patients underwent conventional sonography, contrast-enhanced sonography, and contrast-enhanced CT. The sensitivity, specificity, and diagnostic accuracy were compared. RESULTS Among the 72 patients, 11 cases were benign, and 61 were malignant. The diagnostic accuracy rates for conventional sonography, contrast-enhanced sonography, and contrast-enhanced CT were 66.67% (48 of 72), 90.28% (65 of 72), and 88.89% (64 of 72), respectively. The Youden index showed that contrast-enhanced sonography (0.811) was comparable with contrast-enhanced CT (0.720) and better than conventional sonography (0.159). There were significant differences in accuracy between conventional and contrast-enhanced sonography (P= .001) and conventional sonography and contrast-enhanced CT (P = .001); however, there was no significant difference between contrast-enhanced sonography and contrast-enhanced CT (P = .785). There were significant differences in sensitivity between conventional and contrast-enhanced sonography (P= .006) and conventional sonography and contrast-enhanced CT (P = .006) but no significant difference between contrast-enhanced sonography and contrast-enhanced CT (P > .99). There were no significant differences in specificity among the techniques (P > .05). There was a significant difference in the number of lesions with clear boundaries displayed: 16 on conventional sonography and 56 on contrast-enhanced sonography (P = .006). CONCLUSIONS Contrast-enhanced sonography can show the dynamic blood supply in space-occupying pathologic regions of the extrahepatic bile duct. The diagnostic accuracy of contrast-enhanced sonography in the extrahepatic bile duct was higher than that of conventional sonography and comparable with that of contrast-enhanced CT. Therefore, contrast-enhanced sonography may be a promising imaging technique for diagnosis of space-occupying lesions in the extrahepatic bile duct.

Dielectric barrier discharge in air at atmospheric pressure is produced using nanosecond pulsed supply. The effects of airflows on the discharge characteristics, such as discharge current, breakdown voltage, discharge uniformity, and luminous intensity, are investigated at different discharge gaps and pulse repetitive rates. The peak value of the primary discharge current is increased and the luminous intensity is decreased when the airflow rate increases from 0 to 10 m/s at any discharge gap and pulse repetitive frequency. At 1200-Hz pulse repetitive rate, the discharge becomes more uniform at the bigger discharge gap and the breakdown voltage increases when airflow is introduced into the discharge gap. However, at 100-Hz pulse repetitive rate, the discharge uniformity does not change and breakdown voltage decreases when airflow is introduced into the discharge gap. The experimental results also show that the discharge characteristics have significant changes with the airflow rate increasing from 0 to 10 m/s, while almost no obvious change is observed with the airflow rate increasing from 10 to 30 m/s.

Non-cytotoxicity or good biocompatibility is an essential requisite for the thermo-sensitive polymeric materials used in the biomedical fields. In this study, a new poly(N-acetyl-L-glutamic acid-co-lysine ester) (PGAL) with excellent thermo-sensitivity and biocompatibility is synthesized from natural lysine and glutamic acid. The chemical structures of the monomers and polymers are determined by 1H NMR, FTIR spectrum, and GPC. PGAL shows a reversible lower critical solution temperature (LCST) of 17.3–31.7 °C, and the thermo-sensitivity is affected by its molecular weight, structure, and concentration. The viability of HeLa cells in 0.01–10 μg/mL PGAL solution is found to be in a range of 98–110 % after 24, 48, and 72 h of incubation. To sum up, this new thermo-sensitive PGAL has excellent biocompatibility that makes it a promising material in the biomedical fields.

It is still an open problem in the context of complex scenarios like dynamic background and illumination variations, although numerous moving object detection schemes have been demonstrated. Great efforts have been made to develop some probability distribution pixels obey, for which samples are collected from spatial domain and/or temporal domain. However, significant attention has not been paid to the confidence relationship between pixels and its spatio-temporal neighbours in previous works. In this Letter, a confidence relationship model is proposed to complete the moving object detection task in complex environments. Experiments on typical surveillance scenes verify that the proposed algorithm has attractive robustness and high accuracy for illumination variations and dynamic background against state-of-the-art methods.

To retrospectively summarize the similarities and differences in contrast-enhanced ultrasound (US) findings for lymph node metastasis from adenocarcinoma, squamous carcinoma, and small cell lung cancer.Patients who had received contrast-enhanced US examinations and had a histologic diagnosis of supraclavicular lymph node metastasis from lung cancer were included. The perfusion patterns on contrast-enhanced US images and time-intensity curve parameters were analyzed for the different pathologic types. The microvascular density and microvascular diameter were evaluated.Totally, 61 patients were enrolled in this study, including 26 cases with lung squamous carcinoma, 26 with lung adenocarcinoma, and 9 with small cell lung cancer. Contrast-enhanced US perfusion showed no significant differences in enhancement uniformity during the arterial phase and in the presence of unenhanced areas of metastatic lymph nodes with the 3 different pathologic origins (P .05), but fewer unenhanced areas could be seen in metastatic lymph nodes from adenocarcinoma. The analysis of the time-intensity curve parameters showed that there were significant differences in the peak intensity between metastatic lymph nodes from lung squamous carcinoma and lung adenocarcinoma (P .05). The microvascular density of metastatic lymph nodes from adenocarcinoma was significantly higher than that of metastatic lymph nodes from squamous carcinoma and small cell lung cancer (P .001; P = .0444), whereas the microvascular diameter of metastatic lymph nodes from adenocarcinoma was significantly smaller than that from squamous carcinoma and small cell lung cancer (P = .0277; P .001).Effects of the pathologic diagnosis should be considered when analyzing quantitative parameters of metastatic lymph nodes during contrast-enhanced US examinations, even in the same organ.

In this paper, we discuss the bifurcation of periodic orbits in planar piecewise smooth systems with discontinuities on finitely many smooth curves intersecting at the origin. We assume that the unperturbed system has either a limit cycle or a periodic annulus such that the limit cycle or each periodic orbit in the periodic annulus crosses every switching curve transversally multiple times. When the unperturbed system has a limit cycle, we give the conditions for its stability and persistence. When the unperturbed system has a periodic annulus, we obtain the expression of the first order Melnikov function and establish sufficient conditions under which limit cycles can bifurcate from the annulus. As an example, we construct a concrete nonlinear planar piecewise smooth system with three zones with 11 limit cycles bifurcated from the periodic annulus.

A new multireference perturbation series is derived based on the Rayleigh-Schrödinger perturbation theory. It is orbitally invariant. Its computational cost is comparable to the single reference Møller-Plesset perturbation theory. It is demonstrated numerically that the present multireference second- and third-order energies are size extensive by two types of supermolecules composed of H2 and BH monomers. Spectroscopic constants of F2(X1Σg+),Cl2(X1Σg+),C2-(X2Σg+),B2(X3Σg-),and C2+(X4Σg-) as well as the ground state energies of H2O, NH2, and CH2 at three bond lengths have been calculated with the second multireference perturbation theory. The dissociation behaviors of CH4 and HF have also been investigated. Comparisons with other approximate theoretical models as well as the experimental data have been carried out to show their relative performances.

To explore the diagnostic value of contrast-enhanced ultrasound (CEUS) by comparison with conventional ultrasound (US) and contrast-enhanced CT (CECT) in solid pancreatic lesions.Ninety patients with solid pancreatic focal lesions were enrolled, including 36 cases of pancreatic carcinoma, 28 cases of pancreatitis, 6 cases of pancreatic neuroendocrine tumor, 12 cases of solid pseudopapillary tumor of the pancreas, 6 cases of pancreatic metastases, 1 case of cavernous hemolymphangioma and 1 case of lymphoma. US and CEUS were applied respectively for the diagnosis of a total of 90 cases of solid pancreatic lesions. The diagnostic results were scored on a 5-point scale. Results of CEUS were compared with CECT.(1) 3-score cases (undetermined) diagnosed by CEUS were obviously fewer than that of US, while the number of 1-score (definitely benign) and 5-score (definitely malignant) cases diagnosed by CEUS was significantly more than that of US. There was a significant difference in the distribution of final scores using the two methods (p0.001). The overall diagnostic accuracies of the 90 cases for CEUS and US were 83.33% and 44.44%, respectively, which indicated an obvious advantage for CEUS (p0.001). (2) The diagnostic consistency among three ultrasound doctors: the kappa values calculated for US were 0.537, 0.444 and 0.525, compared with 0.748, 0.645 and 0.795 for CEUS. The interobserver agreement for CEUS was higher than that for US. (3) The sensitivity, specificity and accuracy of the diagnosis of pancreatic carcinoma with CEUS and CECT were 91.7% and 97.2%, 87.0% and 88.9%, and 88.9% and 92.2%, respectively, while for the diagnosis of pancreatitis, the corresponding indices were 82.1% and 67.9%, 91.9% and 100%, and 88.9% and 90%, respectively, showing no significant differences (p0.05).CEUS has obvious superiority over conventional US in the general diagnostic accuracy of solid pancreatic lesions and in the diagnostic consistency among doctors. The performances of CEUS are similar to that of CECT in the diagnosis of pancreatic carcinoma and focal pancreatitis.

Dielectric barrier discharge (DBD) with better uniformity, excited by nanosecond pulses, is achieved within 8 mm air gap by using a self-designed DBD structure in airflow. The self-designed DBD structure is characterized by adding a metal rod (MR) in discharge gap, which will produce a local strong electric field and induce surface and volume discharge. It is observed from sequential single periodic discharge images that the uniformity of discharge starts from the electrode edge at the airflow inlet and moves gradually toward downstream under the action of airflow. When the uniformity of discharge is transmitted to a nearby of MR, a stable uniform and symmetrical annular discharge configuration is formed. Besides, that uniform area can be expanded by adding many MRs or MR array in the discharge gap. There is an optimum distance between every two MRs to produce a continuous and maximum discharge area with better uniformity. The above phenomena are mainly ascribed to the change of electric field distribution caused by MR and the charged particles redistribution induced by airflow.

Experimental investigations of the breakdown characteristics of plate-to-plate dielectric barrier discharge excited by an AC source at different gas flow conditions are carried out. The ignition voltage for the appearance of the very first discharge filament and the breakdown voltage in each discharge half cycle in continuous operation are examined. As revealed by the results of the indoor air experiment, the ignition voltage manifests a monotonous increase with the increase in the gas flow rate, while the breakdown voltage has a marked decline at the low gas flow rate and increases slightly as the gas flow rate is higher than 10 m/s. As regards the obvious decreases in the ignition voltage and breakdown voltage, the decrease in the humidity with the increase in the gas flow rate plays a dominant role. As regards the increase in breakdown voltage, the memory effect from the preceding discharge is considered. The losses of metastable particles, together with particles having high translational energy in the gas flow, are considered to be the most critical factors.

Atmospheric-pressure dielectric barrier discharge (DBD) with airflow participation has been widely used in recent years. In this paper, effects of airflow on DBD characteristics are experimentally investigated by single/double pin-to-plate DBD arrangements with an AC exciting source. The discharge electrical characteristics and the movements of discharge channels in airflow are investigated with a single pin electrode arrangement. The current intensities increase in positive cycles and decrease in negative cycles with the increase in airflow velocity. The transition from a filamentary discharge to a diffuse discharge is observed under certain airflow conditions, and the discharge channels move with the airflow with a movement velocity less than the corresponding airflow velocity. In the cases of double pin electrode arrangements, the repulsion between double pin discharge channels is apparent at a 10 mm distance but is not obvious at a 20 mm distance. When the airflow is introduced into the discharge gap, not as in the case of single pin electrode arrangement, the movements of discharge channels in airflow are affected by adjacent discharge channels. The corresponding reasons are analyzed in the paper.

We concluded that contrast-enhanced ultrasound (CEUS) has clinical value in identifying the pathologic changes of pancreatic carcinomas. Forty-three patients diagnosed with pancreatic carcinoma through surgery were retrospectively investigated. CEUS examinations were performed on all patients before surgery. Enhancement patterns on CEUS were observed. Time-intensity curves of CEUS were generated for the regions of interest in the pancreas, and quantitative parameters were obtained. Resected cancer specimens were stained with hematoxylin and eosin for histologic analysis, and the microvascular density (MVD) of the specimens was determined by CD34 immunohistochemical staining. Enhancement patterns of CEUS were compared with histopathologic findings in pancreatic carcinomas. Correlations between time-intensity curve parameters and microvascular density were analyzed. Twenty cases manifested centripetal enhancement, and 23 cases, global enhancement. The amount of tumor necrosis or mucus in the centripetally enhanced pancreatic carcinomas was greater than that in the globally enhanced pancreatic carcinomas (p = 0.027). Thirty-eight of 43 (88.4%) pancreatic carcinomas manifested hypo-enhancement with a maximum intensity (IMAX)

The objective of our study was to evaluate the clinical utility of performing contrast-enhanced sonography before percutaneous biopsy of focal liver lesions.One hundred eighty-six patients with focal liver lesions detected on either sonography or contrast-enhanced CT were randomly divided into two groups: a group who underwent contrast-enhanced sonography and another who underwent unenhanced sonography. The contrast-enhanced sonography group (79 patients, 129 lesions) underwent SonoVue-enhanced sonography before biopsy, and the unenhanced sonography group (107 patients, 143 lesions) did not undergo contrast-enhanced sonography before biopsy. Conventional sonography was used in all patients to guide the biopsy procedures. The pathologic diagnosis was considered definitive and final if the biopsy result was malignant. If the initial biopsy result was benign or negative for malignancy, then the result was either confirmed or denied on the basis of contrast-enhanced CT, MRI, angiography, serum alpha-fetoprotein level, or clinical follow-up over a period of 6 months. In some patients with suspected malignancy, biopsy was repeated when considered necessary during the follow-up. The diagnostic accuracy of the initial biopsy was defined as the percentage of the total number of lesions that were correctly diagnosed at the initial biopsy. The difference in diagnostic accuracy between the two groups was analyzed to evaluate the value of performing contrast-enhanced sonography before biopsy.Of the 129 lesions in the contrast-enhanced sonography group, 28 (21.7%) were benign and 101 (78.3%) were malignant. Of the 143 lesions in the unenhanced sonography group, 36 (25.2%) were benign and 107 (74.8%) were malignant. There was no significant difference in the distribution of malignant and benign lesions in these two groups (p0.05). There was no statistically significant difference in the distribution of lesions by size between the contrast-enhanced and unenhanced sonography groups (chi(2) = 0.619, p0.05). The diagnostic accuracy of the initial biopsy was significantly higher in the contrast-enhanced sonography group than in the unenhanced sonography group (95.3% vs 87.4%, respectively; p0.05). The diagnostic accuracy of the initial biopsy for malignant lesionsor = 2.0 cm was also significantly higher in the contrast-enhanced sonography group than in the unenhanced sonography group (97.1% vs 78.8%, respectively; p0.05). No major complications occurred in our study except one case of pneumothorax in the unenhanced sonography group.Contrast-enhanced sonography before percutaneous focal liver lesion biopsy improved the diagnostic accuracy of the procedure by providing important intralesional information for differentiating viable, denaturalized, or necrotic tissue; consequently, by providing more accurate information about the site of biopsy even in lesionsor = 2.0 cm, contrast-enhanced sonography before biopsy reduced the number of puncture attempts.

OBJECTIVE. Our purpose was to investigate the correlation of contrast-enhanced sonographic patterns with the histopathology of primary malignancies of the liver. MATERIAL AND METHODS. Of the 318 contrast-enhanced sonographic examinations performed between April and September 2004, 95 patients with 117 lesions confirmed by surgery or biopsy pathology were reviewed in this study. We analyzed the enhancement time and patterns according to the types and degrees of pathologic differentiation. RESULTS. All 65 moderately to poorly differentiated hepatocellular carcinomas (HCCs) enhanced in the arterial phase, and 96.9% (63 lesions) of them quickly washed out in the portal venous phase. All 32 well-differentiated HCCs enhanced in the arterial phase, and 50.0% (16 lesions) washed out slowly during the late phase. The washout time of the two differentiated types was significantly different (p < 0.05). Seventy-five percent of the clear cell carcinomas (12/16) enhanced in the arterial phase, 25% (4/16) did not enhance until the portal venous phase, and 31.3% (5/16) of the clear cell carcinomas washed out slowly during the late phase. The enhancement and washout times of clear cell carcinomas were significantly different than those of moderately to poorly differentiated HCCs (p < 0.05). All four intrahepatic cholangiocarcinomas presented the same patterns as moderately to poorly differentiated HCCs: enhanced in the arterial phase and quickly washed out in the portal venous phase. Among the 72 lesions enhanced homogeneously, 46 lesions (63.9%) were smaller than 3 cm. Thirty-seven lesions (82.2%) of the 45 lesions that enhanced heterogeneously were larger than 3 cm (including the four cholangiocarcinomas). Larger lesions were mainly less differentiated. There were significant differences in tumor sizes in regard to cellular differentiations and types. CONCLUSION. Our study showed that the enhancement manifestations of primary malignancies of the liver are related to pathologic types and grades. Contrast-enhanced sonograms may provide the histopathologic information for malignant tumors of the liver.

A viscoelastic constitutive model of cord-rubber composite is established by introduction of strain energy density function; a new failure criterion is also proposed in terms of different failure modes of unidirectional ply of rubber composite. They are validated by biaxial tensile experimental data of nylon-6 cord-rubber composite. Results show that the proposed large deformation and viscoelastic constitutive model is an effective model for cord-rubber composite and the new failure criterion can be used to predict tensile failure of ply of cord-rubber composite.

Creep and stress relaxation behaviors of unidirectional nylon6–rubber composite under biaxial tensile loading are studied in this paper.Experiments of creep and stress relaxation are performed at room temperatureat different stress levels and different strain levels on both longitudinal andtransverse directions respectively. The influence of different stress levels oncreep strain and the interaction between longitudinal and transverse stressesare studied. Similar analyses are conducted to assess stress relaxation whenspecimens are subjected to biaxial tensile loading. These analyses provide solidexperimental foundation for understanding nylon6–rubber compositeproperties. A new relaxation-type constitutive model is presented for predicting stressrelaxation behaviors under biaxial tensile condition. In this model, octahedralshear strain is introduced as a variable parameter, which is related tolongitudinal strain and transverse strain respectively. Schapery unidirectionalintegral model and the least square method are applied to determine parametersin the constitutive model. Comparisons of experimental data with theoreticalcurves are made and good agreements are obtained for rubber compositesubjected to biaxial tensile loads.

The effects of a parallel magnetic field on the unipolar positive nanosecond pulsed dielectric barrier discharge are experimentally investigated through electrical and spectral measurements. The discharge is produced between two parallel-plate electrodes in the ambient air with a parallel magnetic field of 1.4 T. Experimental results show that both the discharge intensity and uniformity are improved in the discharge with the parallel magnetic field. The intensity ratio of the spectrum at 371.1 nm and 380.5 nm, which describes the average electron density, is increased by the parallel magnetic field. Meanwhile, the intensity ratio of the spectrum at 391.4 nm and 337.1 nm, which describes the electron temperature, is also increased. It is speculated that both the average electron density and the electron temperature are increased by the parallel magnetic field. The aforementioned phenomena have been explained by the confinement effect of the parallel magnetic field on the electrons.

In this investigation, a group of poly(l-malic acid acetate-co-l-lysine ester)s (PMALs) with excellent thermo-sensitivity and non-cytotoxicity were prepared by an optimized synthetic route from natural l-malic acid and l-lysine. The structure and properties of PMALs including monomers were systematically characterized by FTIR, 1H NMR, UV, gel permeation chromatograph, scanning electron microscope, contact angle measurement, cell counting kit assess (CCK-8), and confocal laser scanning microscopy (CLSM). Three PMALs show a reversible lower critical solution temperature of 8–36 °C depending on their chemical structure. The contact angle measurement revealed a considerable discrepancy in the hydrophilicity/hydrophobicity of PMALs and further influence on their thermo-sensitivity. The viability of HeLa cells exposed to 0.2–100 μg/mL PMALs solution was found to be in a range 80–103% after 24, 48, and 72 h of incubation, indicating no cytotoxicity. Moreover, a spherical nanocarrier with core-shell structure was facilely fabricated via the thermo-sensitivity of PMALs and hydrophobicity of drug. CLSM observations manifested that the hydrophobic-curcumin-enwrapped nanocarriers can clearly internalize into the cellular inside. The sustained release of curcumin from nanocarriers in vitro provided a possibility of depressing fast hydrolytic degradation at physiological pH or other side-effects. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 135, 45984.

The plane-to-plane dielectric barrier discharge within 5 mm air gap driven by repetitive nanosecond pulses is studied. A water resistance (WR) is connected in parallel with the discharge circuit. For the discharge without the WR, two reverse discharges occur in the falling front of the voltage pulse, and besides, the primary discharge occurs in the rising front. For the discharge with the WR, only the primary discharge takes place, and the voltage waveform is changed into the unipolar positive voltage pulse with the elevated fall time. Additionally, the discharge with the WR displays the intermediate between the traditional diffuse and filamentary modes. Moreover, the uniformity of the discharge with the WR is increased as the pulse repetition frequency decreases from 1200 Hz to 100 Hz. The above observations in the discharge with the WR are mainly attributed to the increase in the residual charge at the inception of the following pulsed discharge.

To compare the enhancement features of dysplastic nodules with a focus of hepatocellular carcinoma (DN-HCC) versus HCC and regenerative nodules (RN) in cirrhotic patients.One hundred and ninety-three cirrhotic patients were enrolled in this study; they had 215 focal liver lesions, 1.0-3.5 cm in size, which were examined using contrast-enhanced ultrasound (CEUS) with SonoVue(®) and diagnosed as HCC, RN or DN-HCC by biopsy. Samples were obtained using 18-gauge needles in the different enhanced areas. The enhancement features of DN-HCC, HCC and RN were evaluated.There were 86 HCC lesions, 102 RN lesions, and 27 DN-HCC lesions diagnosed by biopsy. Of 86 HCC lesions, 87.2% (75/86) showed complete enhancement during the arterial phase, and 12.8% (11/86) had inhomogeneous enhancement, with no enhancement in the central area during the arterial phase; 100% (86/86) exhibited washout during the late phase. Of 102 RN lesions, 95.1% (97/102) had delayed or simultaneous enhancement during the arterial phase, and 4.9% (5/102) displayed slight enhancement during the arterial phase; 26.5% (27/102) exhibited washout and 73.5% (75/102) exhibited no washout during the late phase. In 27 DN-HCC lesions, only part of the lesions enhanced during the arterial phase and washed out during the late phase; the other areas had delayed or simultaneous enhancement during the arterial phase, and 29.6% (8/27) exhibited slight washout in the late phase. In 86 HCCs, the pathological feature was HCC in the enhanced area of 75 lesions, hepatocellular fatty degeneration in the slightly enhanced area of 7 lesions, and hepatocellular necrosis in the unenhanced area and HCC in the enhanced area of 4 lesions. In 102 RNs, the pathological diagnosis was hepatocyte proliferation with or without fatty degeneration. In 27 DN-HCCs, the pathological feature was HCC in the enhanced area and hepatocyte regeneration in the unenhanced area.CEUS is useful for the diagnosis of focal liver lesions in cirrhotic patients. CEUS can help determine the progression from RN to DN-HCC to HCC by analyzing the hemodynamics. CEUS can promote the diagnostic accuracy of a biopsy by providing more accurate information on the site of the biopsy.

Reservoir management of oilfield (also usually called assets management) is an effective method to improve the performance of reservoir development. A new method to study reservoir management was carried out with system engineering. Reservoir management is looked as a system and it is a sort of system engineering to be established according to the practice of oilfield with Chinese features. Based on system analysis and system structure study, the proceeding of information exchanging and feedback cycles between artificial production subsystem and natural reservoir subsystem are described to support a system dynamics simulation model of compound production–reservoir system. Real data from SL oilfield were run on the model to demonstrate an example. Key index of oilfield development were selected for history fit. Established model was used to predict the production system trend and corresponding advice for reservoir management was put forward based on prediction.

Atmospheric-pressure dielectric barrier discharge (DBD) accompanied by airflow has attracted a significant attention for its extensive applications. In this paper, the effects of airflow on the characteristics of the atmospheric air DBD plasma are experimentally investigated using the DBD reactor excited by a 15 kHz AC power source. In order to study the discharge filaments distribution at different flow rates, transparent conductive indium tin oxide film is used as the upper electrode, and quartz glasses are used as insulated dielectrics. Experiment results prove that the breakdown voltage is decreased and more current pulses with declined amplitudes are produced when the airflow is introduced into the discharge gap. It is confirmed that although the discharge seems to be diffuse in the presence of airflow to the naked eyes, the discharge mode remains filamentary in the intensified charge-coupled device images within a single AC cycle. By acquiring the images with a different exposure time, it can be rec...