Search

The sensitivity of Tunnel Magnetoresistance (TMR) sensors is characterized by significant temperature drift and poor sensitivity drift repeatability, which severely impairs measurement accuracy. Conventional temperature compensation techniques are often hindered by low compensation precision, inadequate real-time performance, and an inability to effectively address the issue of poor repeatability in temperature drift characteristics. To overcome these challenges, this paper introduces a novel method for suppressing temperature drift in TMR sensors. In this method, an alternating reference magnetic field is applied to TMR sensors, and the output amplitude at the frequency of the reference magnetic field is calculated to compensate the sensitivity temperature drift in real time. Temperature characteristic tests were conducted in a non-magnetic temperature test chamber, and the results revealed that the proposed method significantly reduced the TMR sensitivity drift coefficient from 985.39 ppm/°C to 59.08 ppm/°C. Additionally, the repeatability of sensitivity temperature characteristic curves was enhanced, with a reduction in root mean square error from 0.84 to 0.21. This approach effectively mitigates temperature-induced sensitivity drift without necessitating the use of a temperature sensor, and has the advantages of real-time performance and repeatability, providing a new approach for the high-precision temperature drift suppression of TMR. [ABSTRACT FROM AUTHOR]

To investigate the optical characteristics and sources of brown carbon (BrC) in North China, where the atmospheric aerosol loadings are high and have severe impacts on Earth's climate system, we collected fine aerosols (PM 2.5) at an urban site in Tianjin over a 1-year period. We measured the ultraviolet (UV) light absorption and excitation emission matrix (EEM) fluorescence of the water-soluble BrC (WSBrC) and the water-insoluble but methanol-soluble BrC (WI-MSBrC) in the PM 2.5 using a three-dimensional fluorescence spectrometer. The average light absorption efficiency of both WSBrC (Abs365, WSBrC) and WI-MSBrC (Abs365, WI-MSBrC) at 365 nm was found to be highest in winter (10.4 ± 6.76 and 10.0 ± 5.13 Mm-1 , respectively) and distinct from season to season. The averages of the fluorescence index (FI) and the biological index (BIX) of WSBrC were lower in summer than in the other seasons and opposite to that of the humification index (HIX), which implied that the secondary formation and further chemical processing of aerosols were more intensive during the summer period than in the other seasons. However, in winter, the higher HIX together with the higher FI and BIX of WI-MSBrC suggested that the BrC loading was mainly influenced by primary emissions from biomass burning and coal combustion. Based on the EEM, the types of fluorophores in WSBrC were divided into humic-like substances (HULIS), including low-oxygenated and high-oxygenated species and protein-like compounds (PLOM), though mostly PLOM in the WI-MSBrC. The direct radiation absorption by both WSBrC and WI-MSBrC in the range of 300–400 nm accounted for ∼ 40 % of that (SFEAbs , 4.97 ± 2.71 and 7.58 ± 5.75 Wg-1 , respectively) in the range 300–700 nm. [ABSTRACT FROM AUTHOR]

Objective To investigate the relation between serum markers, the degree of lesions and the active peri⁃ od of chronic periodontitis in patients with type 2 diabetes mellitus. Methods A total of 595 patients with type 2 dia⁃ betes mellitus were selected, and oral examinations and laboratory tests were conducted. The patients were divided into a periodontally healthy group mild, moderate and severe periodontitis groups depending on the diagnostic criteria for chronic periodontitis. The patients were also divided into periodontally healthy, resting and active groups depending on the diagnostic criteria of the active period. The relationships between serum biochemical indices, the degree of lesions and chronic periodontitis activity were analyzed. Results The prevalence of chronic periodontitis in patients with type 2 diabetes was 74.6% , and the proportions of patients with mild, moderate, and severe chronic periodontitis were 44.9%, 16.1% and 13.6%, respectively. The composite ratio of active periodontal chronic periodontitis was 33.1%. Com⁃pared with the patients in the control group, the fasting plasma glucose and HbA1c levels were more poorly controlled in the type 2 diabetes mellitus groups with chronic periodontitis (P < 0.05). There were significant differences in fasting blood glucose levels between mild periodontitis group and moderate, severe periodontitis group (P < 0.05). There was no significant difference in HbA1c levels among the mild, moderate and severe groups (P＞0.05). However, there were sig⁃ nificant differences in fasting blood glucose levels between the groups with various degrees of progression in the follow⁃ ing order: active (11.24 mmol /L) > resting (9.64 mmol/L) > control (8.82 mmol/L) (P < 0.05). Conclusion The severi⁃ ty of chronic periodontitis plays no role in the level of HbA1c, instead, the level of fasting plasma glucose changes with the severity and progression of chronic periodontitis.

To understand the characteristics of chemical components and dicarboxylic acids, oxocarboxylic acids and α‐dicarbonyls in atmospheric aerosols at underground coal fire environment, we collected fine aerosols (PM2.5) from Wuhai, Inner Mongolia, North China, where the underground coal fire often occurs. PM2.5 samples were analyzed for the measurements of carbonaceous components, stable carbon isotopic composition (δ13C) of total carbon, and molecular distribution and compound‐specific δ13C of diacids, oxoacids and α‐dicarbonyls. Oxalic acid (C2) was the most abundant species, accounting for 43.2%–63.1% (avg. 50.8%) of total diacids, followed by phthalic acid (Ph) (13.7%). Azelaic acid (C9) was the third most (7.4%) abundant, followed by succinic (C4) and malonic (C3) acids. Significant correlations of C2 diacid with glyoxylic (ωC2) and 3‐oxopropanoic (ωC3) acids and C3 diacid and their δ13C implied that diacids and related compounds were mainly derived from the underground coal fire emissions and subsequent in situ secondary formation. Based on molecular distribution, seasonal pattern and linear relations of C9 diacid with C2, C3, ωC2 and ωC3 as well as with Ph acid and total diacids, together with the comparability and similarity of its δ13C (−27.0 ± 0.9‰) with that of Ph acid and organic matter in coals, respectively, we found that the C9 diacid has been mainly derived from its precursors such as unsaturated fatty acids emitted from underground coal fires and their subsequent in situ photochemical oxidation. However, further research is needed to confirm such an importance of coal combustion for azelaic acid loading in atmospheric aerosols. Plain Language Summary: Fine aerosols in the atmosphere cause high uncertainty in radiative forcing of the Earth's climate system and have become one of the serious environmental risk factors, causing more than 6 million premature deaths annually. The atmospheric environment over the underground coal fire field is different from that in urban area, because the emission of inorganic gaseous species, volatile organic compounds and particulates that consist oxygen‐containing organic species and polycyclic aromatic hydrocarbons and their subsequent photochemical oxidation processes are relatively larger at the coal fire field. Our study on fine aerosols from underground coal fire field at Wuhai, North China showed a rather large abundance of dicarboxylic acids associated with a specific partitioning from the coal fires compared to observations from other environments including an unusual abundance of azelaic acid. Key Points: The characteristics of diacids in atmospheric aerosols at underground coal fire environment have been investigatedAzelaic acid could be applied in evaluating the coal combustion influence on secondary organic aerosols in the atmosphereC2 was mainly derived from underground coal fire emissions and their subsequent in situ photochemical oxidation [ABSTRACT FROM AUTHOR]