Epidemiological survey on prevalence and associated risk factors of bitter taste among inpatients from four Grade 3A hospitals in Beijing

Objective:To study the possible etiology of bitter taste in the mouth and its diagnostic significance by an epidemiological survey on its associated diseases and influence factors.Methods:A cross-sectional epidemiological study was conducted by recruiting patients from four Grade 3A hospitals in Beijing.The questionnaire incorporated five aspects i.e.general information,gustation,behavior,symptomology and past medical history.SPSS20.0 software package was used for data analysis.T-test and chi-square test were selected for evaluation.An observation of the correlation between different causative factors and the symptoms of bitter taste was analyzed by Logistic regression.Results:Smoking and excessive consumption of meat and emotional stress were the risk factors,while eating fresh fruits and vegetables were key protective elements against the manifestation of bitter taste in the mouth.The incidence of bitter taste was high in patients suffering from gastroesophageal disease,hepatic and gallbladder diseases and neurological diseases.Conclusion:Bitter taste is a common symptom in hospitalized patients,especially in patients with gastroesophageal reflux and liver and gallbladder diseases and the link to smoking,dietary and emotional stress.It is found that smoking is a sole risk factor for the manifestation of bitter taste.

The noise spectral characteristics and noise reduction schemes of screw air-source heat pump:A case study

The screw air-source heat pump can cause incessant high noise levels during operation,which might hinder adoption of this energy-efficient heat pump.First,acoustic measurements and comparison testing were performed in this research.The measurements revealed that the compressor is the main noise source of the heat pump,and it shows a multipeak frequency distribution and a wide frequency spectrum under different work conditions,with multiple peaks at 63,250,and 1000 Hz.Then,a compressor sound insulation cover with broadband absorption was proposed,and it was experimentally proven that the insulation cover can reduce the maximum sound pressure level of one unit from 89.8 dBA to 79.1 dBA.Third,we proposed several noise reduction strategies and compared their noise reduction effects using computer simulation.The results showed that the noise problem can be effectively improved through the rational design of the sound barrier and the layout and opening options of heat pump.The distance between the sound barrier and heat pump and the sound attenuation due to diffraction ALa exhibit a U-shaped relation.For buildings of different heights,the optimal heights of noise barrier are proposed.The 5.5-meter is the optimal height of the sound barrier for single-story buildings.The conclusions can be applied to other building projects for heat pump noise reduction.