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In this paper, a frequency domain simulation method of magneto-acousto-electrical tomography (MAET) was proposed. This method is based on discrete Fourier transform. With this approach, the solving degrees of freedom of the simulation model can be significantly reduced. It can greatly reduce the requirements of computer hardware and improve efficiency. At the same time, the interaction between fluid and biological tissues was considered, which makes the simulation model closer to the real model. In this paper, an MAET simulation model of acoustic–solid–electromagnetic multi-physical field coupling corresponding to the actual physical world was established. It is more reasonable to adopt the fully coupled method. However, the fully coupled method needs more computational memory. To further study the memory and time required for calculation, the segregated method was used to calculate the simulation model without affecting the accuracy and tolerance in this paper. The results show that using the segregated method can significantly reduce the memory requirement of the MAET model, but the solution time will increase accordingly. Therefore, the appropriate solution method can be selected according to the simulation computer configuration and the desired solution time. We, finally, built an experimental platform to conduct MAET experiments and verified the theoretical and simulation analyses. [ABSTRACT FROM AUTHOR]

Magneto-Acousto-Electrical Tomography (MAET) has the advantage of high spatial resolution and high image contrast and is expected to achieve early breast cancer diagnosis. At present, the density of biological tissue is usually assumed to be the density of water. The effect of density changes on the MAET signal has not been studied. Liposarcoma of the breast is a common malignant tumor. Unlike normal breast cancer which occurs in the gland, liposarcoma of the breast occurs in the fat of the breast. However, the fat density of the breast is widely distributed, which is different from that of liposarcoma. Therefore, it is very important to study the effect of density change on the MAET signals. In this paper, a finite element simulation model is established to consider the influence of density variation on the MAET signal. The simulation results show that an increase in density reduces the amplitude of the original MAET signal. The degree of reduction in signal amplitude is proportional to the increase in signal density. The simulation results are consistent with the theoretical analysis. Finally, the MAET experimental platform is built to validate the simulation results of MAET signals. The simulation and experiment results show that the change of density greatly influences the detection of breast liposarcoma based on MAET. It cannot be directly equivalent to the density of water. The results of this study indicate that MAET is expected to detect the early diagnosis of breast liposarcoma. [ABSTRACT FROM AUTHOR]

ABSTRACT: In this work, three dianhydrides with similar chemical structures, 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride (BTDA), 4,4′‐oxydiphthalic anhydride (ODPA), and pyromellitic dianhydride (PMDA), are employed for the crosslinking modification of poly(vinyl alcohol) (PVA) membranes for ethanol dehydration via pervaporation. The changes in crosslinking degree, surface hydrophilicity, and glass‐transition temperature are investigated and compared. Compared to the pure PVA membrane, all crosslinked membranes show higher fluxes but lower separation factors, because of the higher fractional free volume and the lower hydrophilicity by the crosslinking of the PVA matrix, respectively. In addition, all crosslinked PVA membranes exhibit similar flux, and the separation factor presents a decreasing order of PVA/PMDA‐2 > PVA/ODPA‐2 > PVA/BTDA‐2, which is in the reverse order of their hydrophilicity, probably because of the reduction in the swelling resistance. With the PMDA content increasing from 0.01 to 0.04 mol/(kg PVA) in the PVA/PMDA crosslinked membranes, the crosslinking degree is enhanced and the hydrogen bonding is weakened, resulting in a flux increase from 120.2 to 190.8 g m−2 h−1, but the separation factor declines from 306 to 58. This work is believed to provide useful insight on the chemical modification of PVA membranes for pervaporation and other membrane‐based separation applications. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46159. [ABSTRACT FROM AUTHOR]

New Findings What is the central question of this study? Does antagonism of V1b receptors prevent the haemodynamic and renal sympathetic nerve responses that occur with application of exogenous vasopressin into the paraventricular nucleus (PVN) of conscious, chronically instrumented rats?, What is the main finding and its importance? Microinjection of vasopressin into the PVN increased mean arterial pressure, heart rate and renal sympathetic nerve activity, all of which were inhibited by pre-injection of the PVN with the V1b antagonist, nelivaptan. The administered vasopressin did not enter the peripheral circulation or increase plasma vasopressin. Ganglionic blockade prevented each of the responses, consistent with mediation by enhanced sympathetic output rather than an increase in circulating vasopressin., Vasopressin (VP) participates in regulation of haemodynamics and volume. Besides more classical actions as a circulating hormone, VP may act via release from axons and dendrites within the CNS. The paraventricular nucleus (PVN) possesses vasopressinergic neurons and a dense complement of VP receptors, including the V1b receptor, which has been implicated in several types of stress responses. We tested the hypothesis that antagonism of V1b receptors will prevent VP-induced increases in mean arterial pressure (MAP), heart rate (HR) and renal sympathetic nerve activity (RSNA). Studies were performed in conscious male Sprague-Dawley rats chronically instrumented with vascular catheters, renal nerve electrodes and a cannula stereotaxically directed into the PVN. Unilateral microinjection of VP into the PVN significantly increased MAP, HR and RSNA, peaking at 10 min. Pre-injection of the PVN with the selective V1b receptor antagonist, nelivaptan, did not alter baseline values but blocked the responses to VP. Ganglionic blockade with chlorisondamine decreased MAP and HR and abolished their increase in response to subsequent PVN application of VP. Injection of VP into the PVN did not alter plasma VP levels. Paraventricular nucleus injection with radiolabelled VP resulted in negligible radiolabelled VP in peripheral blood. These findings support the concept that, in basal conditions, PVN V1b receptor activation (rather than VP release into the periphery) may be implicated in the increases in MAP, HR and RSNA due to increased sympathetic outflow. While the role of V1a and oxytocin receptors cannot be excluded, these data suggest that further studies of the role of V1b receptor activation by endogenous VP during stress to effect neuroexcitation are warranted. [ABSTRACT FROM AUTHOR]

Highlights • Peri-urban regions provide ecological, social and economic functions. • Six crops grown in Beijing's peri-urban region were evaluated. • The multiple functions of peri-urban agriculture are not always complementary. • A multi-dimensional index showed the benefits of cash and organic crops over cereals. Abstract Urbanization has proceeded rapidly in China, bringing large-scale social, economic and environmental change to the strategically important peri-urban regions that surround expanding cities. In the Beijing Metropolitan Region, with an area of 16,411 km2, government policies have sought the development of multi-functional peri-urban agriculture, favoring the production of cash crops, and the area of vegetable, fruit and organically grown cereal production has increased, whereas the area under conventional cereal production has declined. In this study, six characteristic agricultural practices in the peri-urban zone were compared in terms of energy use efficiency, economic and environmental performance. A multi-dimensional index was also constructed to compare overall performance. Conventional cereal cropping of spring maize (AP1) and winter wheat-summer maize (AP2) had the lowest energy inputs, highest energy use efficiency, and a positive net energy balance. However, cash crops (greenhouse watermelon-tomato, open-field peach; AP3 and AP4) and organically produced crops (Chinese chestnut, millet; AP5 and AP6) achieved substantially higher economic returns per ha cultivated. Fruit and vegetable crops also achieved much higher yields than conventionally grown cereals. Organically produced crops, although higher in value, achieved lower yields. Product carbon footprints ranged from 0.53 to 6.1 kg CO 2 eq kg−1 and were lowest for fruit and vegetables. Water consumption ranged from <0.1 L kg−1 for Chinese chestnut to 435 L kg−1 for the outputs of the winter wheat-summer maize rotation. When the various indicator results were combined using a multi-dimensional index, the ranking of the different peri-urban agricultural practices was AP6 > AP5 > AP3 > AP1 > AP4 > AP2. These results demonstrate that the multiple functions of per-urban agriculture are not always complementary. However, the adjustment of peri-urban agricultural practices in the Beijing Metropolitan Region appears to be increasing overall benefits. Nevertheless, benchmarking against practices in other parts of China and the world, suggests that there is substantial scope for improvement of peri-urban agriculture in the Beijing Metropolitan Region, with excessive N fertilization identified as a major contributing factor for the performance gap. The development of peri-urban agriculture in Beijing, as elsewhere, has emphasized multi-functionality, providing local food supply, economic returns for local farmers, ecological functioning, along with amenity. Different agricultural practices provide these benefits in different ways. Assessments that address only a single aspect risk informing decisions that have adverse unintended consequences. Studies employing a variety of indicators across the social, economic and environmental dimensions are required if the potential benefits of peri-urban agriculture are to be realized. [ABSTRACT FROM AUTHOR]

The Paddy Land-to-Dry Land (PLDL) program, which is a representative example of payment for watershed ecosystem services, has played a critical role in protecting the source of the Beijing Municipality's water supply in the Miyun Reservoir watershed since 2006. Previous studies have evaluated the program's benefits and costs and confirmed its positive impacts. However, local farmers' Willingness to Accept (WTA) for compensation, its impact factors and relevant policies, which are key factors determining its successful implementation, have not been analyzed. In this paper, a hypothesis argues that positive ecological impacts could lead to decreasing WTA values, whereas negative ecological effects could lead to increasing values. The study areas comprised three counties in Hebei Province and one district in Beijing Municipality. A total of 391 randomly selected farmers (with a response rate of 92%) participated in a face-to-face questionnaire-based survey. The contingent valuation method was applied as the main analytical tool for evaluating nonmarket environmental goods or services. Interval regression of the Tobit model was applied to analyze WTA impact factors and was validated using a logit model. The study's findings confirmed the positive effects of the PLDL program, but they did not confirm the lower WTA values that were hypothesized in the study areas. This disparity between the hypothesis and survey results can be explained in three dimensions: environmental, economic, and social. First, environmental awareness had a strong positive correlation with WTA. Respondents who valued environmental protection above economic development required higher compensation. Second, respondents' gender and household's incomes were closely related to their environmental awareness, but were not directly related to the dependent variable of WTA. Third, respondents whose degree of equity relating to the program was lower than that of others required a higher payment. Moreover, an ecological service (ES) provider's age and WTA were negatively related, younger respondents demanded a higher value for payment-related WTA in the study areas. Therefore, policymakers' decisions regarding ecological compensation should evidently take into account WTA impact factors in the PLDL program, especially ES providers' ages, their environmental awareness, and the degree of equity that they have. [ABSTRACT FROM AUTHOR]

Selective stimulation of inhibitory A1 and facilitatory A2a adenosine receptor subtypes located in the nucleus of the solitary tract (NTS) powerfully inhibits cardiopulmonary chemoreflex (CCR) control of regional sympathetic outputs via different mechanisms: direct inhibition of glutamate release and facilitation of an inhibitory neurotransmitter release, respectively. However, it remains unknown whether adenosine naturally released into the NTS has similar inhibitory effects on the CCR as the exogenous agonists do. Our previous study showed that adenosine is released into the NTS during severe hemorrhage and contributes to reciprocal changes of renal (decreases) and adrenal (increases) sympathetic nerve activity observed in this setting. Both A1 and A2a adenosine receptors are involved. Therefore, we tested the hypothesis that, during severe hemorrhage, CCR control of the two sympathetic outputs is attenuated by adenosine naturally released into the NTS. We compared renal and adrenal sympathoinhibitory responses evoked by right atrial injections of 5HT3 receptor agonist phenylbiguanide (2-8 μg/kg) under control conditions, during hemorrhage, and during hemorrhage preceded by blockade of NTS adenosine receptors with bilateral microinjections of 8-(p-sulfophenyl) theophylline (1 nmol/100 nl) in urethane/chloralose anesthetized rats. CCR-mediated inhibition of renal and adrenal sympathetic activity was significantly attenuated during severe hemorrhage despite reciprocal changes in the baseline activity levels, and this attenuation was removed by bilateral blockade of adenosine receptors in the caudal NTS. This confirmed that adenosine endogenously released into the NTS has a similar modulatory effect on integration of cardiovascular reflexes as stimulation of NTS adenosine receptors with exogenous agonists., (Copyright © 2014 the American Physiological Society.)

Previously we have shown that adenosine operating via the A(1) receptor subtype may inhibit glutamatergic transmission in the baroreflex arc within the nucleus of the solitary tract (NTS) and differentially increase renal (RSNA), preganglionic adrenal (pre-ASNA), and lumbar (LSNA) sympathetic nerve activity (ASNA>RSNA≥LSNA). Since the cardiopulmonary chemoreflex and the arterial baroreflex are mediated via similar medullary pathways, and glutamate is a primary transmitter in both pathways, it is likely that adenosine operating via A(1) receptors in the NTS may differentially inhibit regional sympathetic responses evoked by activation of cardiopulmonary chemoreceptors. Therefore, in urethane-chloralose-anesthetized rats (n = 37) we compared regional sympathoinhibition evoked by the cardiopulmonary chemoreflex (activated with right atrial injections of serotonin 5HT(3) receptor agonist phenylbiguanide, PBG, 1-8 μg/kg) before and after selective stimulation of NTS A(1) adenosine receptors [microinjections of N(6)-cyclopentyl adenosine (CPA), 0.033-330 pmol/50 nl]. Activation of cardiopulmonary chemoreceptors evoked differential, dose-dependent sympathoinhibition (RSNA>ASNA>LSNA), and decreases in arterial pressure and heart rate. These differential sympathetic responses were uniformly attenuated in dose-dependent manner by microinjections of CPA into the NTS. Volume control (n = 11) and blockade of adenosine receptor subtypes in the NTS via 8-(p-sulfophenyl)theophylline (8-SPT, 1 nmol in 100 nl) (n = 9) did not affect the reflex responses. We conclude that activation of NTS A(1) adenosine receptors uniformly inhibits neural and cardiovascular cardiopulmonary chemoreflex responses. A(1) adenosine receptors have no tonic modulatory effect on this reflex under normal conditions. However, when adenosine is released into the NTS (i.e., during stress or severe hypotension/ischemia), it may serve as negative feedback regulator for depressor and sympathoinhibitory reflexes integrated in the NTS.

Breviscapine, a traditional Chinese medicine, is extensively used in clinic to treat cardiovascular diseases and cerebrovascular injury. In this study, we demonstrated the effects of breviscapine on vascular dementia (VD) rats, which were mimicked by permanent occlusion of bilateral common carotid arteries. Breviscapine (2 mg/kg for 14 d) improved the performance of learning and memory of VD rats in Morris water maze, decreased the level of lipid peroxidation and free radicals, and attenuated the pathological alterations, such as nuclear shrink, cellular edema and irregular arrangement of pyramidal layer in the hippocampal CA(1) area. In vitro experiment, breviscapine (50 microg/l) protected cortical neuron from injury and decreased intracellular calcium overloading induced by H2O2 (10 mM). The results suggest that breviscapine has therapeutic effect on cerebral ischemia and vascular dementia.