Study of microwave non-thermal effects on hydrogen bonding in water by Raman spectroscopy.

Microwave chemistry plays an important role in organic synthesis. It has been debatable whether or not there are microwave non-thermal effects. Through analyzing the Raman spectra of pure water under two different heating methods (oil bath and microwave), the existence of microwave non-thermal effect is verified in this paper. The findings demonstrate that temperature has a significant impact on the Raman shift of the OH stretching band, which shifts to a high wave number as temperature rises and deforms the hydrogen bond (HB) network structure. Because microwave electric fields selectively heat water molecules (polar molecules) and destroy hydrogen bond structures in water, results in microwave heating more severe destruction of fully hydrogen-bonded structure than oil bath and transforms it more quickly into the partially hydrogen-bonded and free H2O structure. Under the non-thermal effects of microwaves, hydrogen bonds that initially existed as stable tetrahedral structures are transformed into chain-like structures more rapidly. By comparing the Raman shift, it can be found that the microwave non-thermal effect can affect the hydrogen bonding in water for a long time (>1h). This study provides an experimental basis for enriching the mechanism of microwave non-thermal effects on hydrogen bonding.

Transient Heat Transfer Characteristics in a Flat Plate Heat Sink with Mini-Channels for Cooling High Heat Flux IGBT.

Effective cooling of a high heat flux IGBT electronic system is highly related to system efficiency and safety. A flat plate heat sink was designed to experimentally investigate the transient heat transfer characteristics of IGBT cooling. It is made of aluminum with 20 mini-channels of 249 mm × 3 mm × 4 mm dimensions, which were manufactured by milling machines and melt inert gas (MIG) welding technology to ensure no deformation. Experiments were conducted using deionized water at atmospheric pressure with flow rates of 3.2-9.5 L/min and heat fluxes of 104-347 W/cm2. It was found that instantaneous start-stop and transient heating power variation might cause IGBT failure, especially under low Reynolds and Nusselt number conditions. The temperature rise rate and cooling rate vary with different system parameters. Heating rate can be reduced by high flow rate due to local subcooled boiling. The concept of respond time (RT) based on the piecewise function is suggested to evaluate the influence of transient condition on heating rate. Analysis of flow fluctuation indicated that it would not be a threat to the system except for in extreme cases. These findings provide a reference for the considerations of the design and manufacture of IGBT cooling flat plate heat sinks with mini-channels.

Oral myiasis after cerebral infarction in an elderly male patient from southern China: A case report.

BACKGROUND: Myiasis is a rare but risky pathology caused by a parasitic infestation of humans and animals by the dipterous larva. Oral myiasis occurs when soft tissues of the oral cavity are invaded by the larvae of flies. It is not a common disease for the reason that the oral cavity is not easily reachable for the fly to lay eggs. But it can cause pain, infection, uncomfortable feeling when the worms move, tissue destruction and/or even life-threatening hemorrhages. CASE SUMMARY: We reported a case of oral myiasis after cerebral infarction in a 78-year-old male patient from southern China (Guangdong Zhanjiang). As a result of cerebral infarction, he suffered from right hemiplegia, mobility and mental decline for about 3 mo. He had difficulty swallowing and was fed via a feeding tube. He mostly engaged in mouth breathing and had poor oral and dental hygiene. More than 20 live larvae were collected from the patient's oral cavity, which were localized in the maxillary gingiva, the mandibular gingiva and the tongue. The patient recovered after the routine oral cleaning, removal of maggots, debridement and anti-infection treatment. CONCLUSION: Early diagnosis and treatment of this infestation are essential due to the bothersome symptoms, such as inflammation, intense anxiety over the larvae movement, possible serious complications, etc. Clinical staff should be familiar with this infestation, and this disease should be considered, especially in physically and mentally disabled patients or those at significant risk for infection. Necessary measures, including good sanitation, personal and environmental hygiene and special care should be adopted so as to prevent this disease.

Methanol to aromatics: isolated zinc phosphate groups on HZSM-5 zeolite enhance BTX selectivity and catalytic stability.

HZSM-5 zeolite combined with unique zinc and phosphorus species, yields excellent selectivity (∼85%) to BTX (benzene, toluene, xylenes) in aromatic products. It was found that both zinc and phosphorus species were highly distributed in the pores of the zeolite channel network to form isolated zinc phosphate groups, which directly bond to the surface of zeolite, leading to a strong Lewis acidic center and an optimized surface acidity distribution favorable for BTX formation and the hydrothermal stability of the catalyst.

Thermal Modelling Analysis of Spiral Wound Supercapacitor under Constant-Current Cycling.

A three-dimensional modelling approach is used to study the effects of operating and ambient conditions on the thermal behaviour of the spiral wound supercapacitor. The transient temperature distribution during cycling is obtained by using the finite element method with an implicit predictor-multicorrector algorithm. At the constant current of 2A, the results show that the maximum temperature appears in core area. After 5 cycles, the maximum temperature is 34.5°C, while in steady state, it's up to 42.5°C. This paper further studies the relationship between the maximum temperature and charge-discharge current. The maximum temperature will be more than 60°C after 5 cycles at the current of 4A, and cooling measurements should be taken at that time. It can provide thoughts on inner temperature field distribution and structure design of the spiral wound supercapacitor in working process.

Unregulated emissions from diesel engine with particulate filter using Fe-based fuel borne catalyst.

The alteration and formation of toxic compounds and potential changes in the toxicity of emissions when using after-treatment technologies have gained wide attention. Volatile organic compound (VOC), carbonyl compound and particle-phase polycyclic aromatic hydrocarbon (PAH) emissions were tested at European Steady State Cycle (ESC) to study unregulated emissions from a diesel engine with a fuel-borne catalyst and diesel particulate filter (FBC-DPF). An Fe-based fuel-borne catalyst was used for this study. According to the results, brake specific emissions of total VOCs without and with DPF were 4.7 and 4.9mg/kWh, respectively, showing a 4.3% increase. Benzene and n-undecane emissions increased and toluene emission decreased, while other individual VOC emissions basically had no change. When retrofitted with the FBC-DPF, total carbonyl compound emission decreased 15.7%, from 25.8 to 21.8mg/kWh. The two highest carbonyls, formaldehyde and acetaldehyde, were reduced from 20.0 and 3.7 to 16.5 and 3.3mg/kWh respectively. The specific reactivity (SR) with DPF was reduced from 6.68 to 6.64mg/kWh. Total particle-phase PAH emissions decreased 66.4% with DPF compared to that without DPF. However, the Benzo[a]pyrene equivalent (BaPeq) with DPF had increased from 0.016 to 0.030mg/kWh. Fluoranthene and Pyrene had the greatest decrease, 91.1% and 88.4% respectively. The increase of two- and three-ring PAHs with DPF indicates that the fuel-borne catalyst caused some gas-phase PAHs to adsorb on particles. The results of this study expand the knowledge of the effects of using a particulate filter and a Fe-based fuel-borne catalyst on diesel engine unregulated emissions.

[Reestablishment of sensory function after greater auricular nerve implanted into flap for reconstruction of buccal defect in rabbits].

OBJECTIVE: To assess the sensory restoration after the greater auricular nerve is implanted into the flap to repair the buccal defect in rabbits. METHODS: Fifteen Japanese white rabbits, weighing 2.0-2.5 kg, were randomly divided into the experimental group (nerve implanted), the control group (nerve unimplanted), and the normal group (without any treatment). In the experimental and the control group, circular defects (2.0 cm x 2.0 cm) were constructed in the left cheek of the rabbits. Then, the cervical flaps (4.5 cm x 2.5 cm) were transferred and the great auricular nerve was implanted into the defects in the experimental group, and the flaps without any nerve were implanted into the defects in the control group. The subjects in the normal group were given no treatment. After 6 months, the nerve discharge, the HE staining, and the immunohistochemical method were used to assess the regeneration of the nerve fibers. RESULTS: The nerve discharge and the percentage of the different kinds of the nerve fibers in the experimental group (124.2 +/- 33.8 roots) were not statistically different from those in the normal group (138.4+/-20.4 roots, P>0.05), but significantly different from those in the control group (18.8+/-5.6 roots, P<0.05). In the center of the flap in the experimental group, the receptive field of the nerve fibers was identical to the implanting approach of the greater auricular nerve. The HE staining and the immunohistochemical staining showed that the density of the regenerated fibers in the center of the flap in the experimental group reached the normal level. There was no regenerated fibers in the control group. CONCLUSION: The great auricular nerve implanted into the cervical flaps has a good effect on reconstruction of the buccal defect in rabbits.