Controls on the organic carbon content of the lower Cambrian black shale in the southeastern margin of Upper Yangtze

Control of various factors, including mineral components, primary productivity and redox level, on the total organic carbon(TOC) in the lower Cambrian black shale from southeastern margin of Upper Yangtze(Taozichong, Longbizui and Yanbei areas) is discussed in detail in this article. Mineral components in the study strata are dominated by quartz and clay minerals. Quartz in the Niutitang Formation is mainly of biogenic origin, and the content is in positive correlation with TOC, while the content of clay minerals is negatively correlated with TOC. Primary productivity, represented by the content of Mobio(biogenic molybdenum), Babio(biogenic barium) and phosphorus, is positively correlated with TOC. The main alkanes in studied samples are nCC, and odd–even priority values are closed to 1(0.73–1.13), which suggest the organic matter source was marine plankton. Element content ratios of U/Th and Ni/Co and compound ratio Pr/Ph indicate dysoxic–anoxic bottom water, with weak positive relative with TOC. In total, three main points can be drawn to explain the relationship between data and the factors affecting organic accumulation:(1) quartz-rich and clay-mineral-poor deep shelf–slope–basin environment was favorable for living organisms;(2) high productivity provided the material foundation for organic generation;(3) the redox conditions impact slightly on the content of organic matter under high productivity and dysoxic–anoxic condition.

Comparison between Bilateral and Unilateral Sudden Sensorineural Hearing Loss

Background：Bilateral sudden sensorineural hearing loss （BSSHL） is rare and assumed to be a different clinical entity compared to unilateral SSHL （USSHL）.This study examined the differences between the idiopathic BSSHL and USSHL.Methods：Forty-six sequential BSSHL patients （Se-BSSHL） and 68 simultaneous BSSHL （Si-BSSHL） were consecutively admitted between June 2008 and December 2015.Two sets of patients served as control groups：（1） USSHL patients with healthy contralateral ear and （2） USSHL patients with contralateral preexisting hearing loss （USSHLwCHL）.We retrospectively analyzed differences among four cohorts using analysis of variance,Kruskal-Wallis test,Welch＇s t-test,and Chi-square test as appropriate before and after propensity score matching （PSM） based on age,gender,and body mass index （BMI）.Results：The prevalence of idiopathic BSSHL was 8.6% （114/1329） among the total SSHL patients.In the total cohort,USSHL patients tended to be younger,female,and tended to have lower BMI,renal parameters,and total cholesterol in addition to higher high-density lipoprotein compared to the other three groups.Most routine blood indicators,some coagulation markers,and immunoglobulin M （H =13.4,P =0.004） were significantly different among the study groups.After PSM,the major significant differences were found in audiometric characteristics.Si-BSSHL and Se-BSSHL patients demonstrated similar hearing thresholds as USSHL but were significantly better than the USSHLwCHL patients across most frequencies before and after treatment （H =30.0,P 〈 0.001 for initial hearing and H =12.0,P =0.007 for final hearing）.Moreover,the BSSHL patients showed different hearing loss distribution patterns （more descending type,x2 =33.8,P =0.001） with less hearing gain （H =17.5,P 〈 0.001） compared to the USSHL patients.Conclusions：Idiopathic BSSHL is a relatively rare subtype of SSHL with a higher rate of descending audiogram type and inferior hearing outcome rather than being classified as a completely different disease entity compared to USSHL.