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• A neutral tone tends to approach a low pitch target in Plastic Mandarin. • Same low pitch target of neutral tone across two Mandarin varieties. • Mandarin neutral tone may be underspecified and attract the boundary tone. • Stable transfer of prosodic structure in the Standard-Plastic Mandarin variation. With an aim to investigate the nature of Mandarin neutral tone through the lens of language variation and change, this study examines the pitch patterns of speech sequences containing neutral tone syllables, i.e. those that do not have any of the four canonical lexical tones and are often overlooked in prior studies of tones, in two Mandarin varieties: Standard Mandarin and Plastic Mandarin spoken in Changsha, China. Using Generalised Additive Mixed Models, the study shows (a) that f0 contours of a sequence of neutral tone syllables following various lexical tones converge in the end at a low pitch in both Mandarin varieties, and (b) that the low pitch target of neutral tone syllables tends to be the same across the two Mandarin varieties. The cross-dialectal comparison favours the phonological account that neutral tone is underlyingly underspecified and attracts the boundary tone. It suggests that the constant pitch target across two Mandarin varieties with distinct lexical tone contours may be attributed to the stable transfer of prosodic structure in the Standard-Plastic variation. [ABSTRACT FROM AUTHOR]

The mechanism of electron transmission in combined nanoiron-bacteria denitrification cannot be explained by the classic model, in which an Fe 0 H 2 -nitrate transferring chain is proposed. In this study, we used characteristic techniques and electrochemical analysis to investigate the necessity of molecular hydrogen for the combined denitrifying system using commercial nanoiron with Alcaligenes eutrophus , and to analyze its potential electron donor. Based on our results, nitrate removal and its by-products (NO 2 − and NH 4 + ) generation was not significantly affected by residual H 2 gas, indicating that H 2 was not necessary for hydrogenotrophic denitrification. As to the potential electron donor analysis, nanoscale zero-valent iron did not appear to be the electron donor due to its high level of toxicity (83% mortality using nanoiron versus 36% in the control cells). In addition, when iron oxides (Fe 3 O 4 , Fe 2 O 3 and FeOOH on the nanoiron surface) and free ferrous ions [Fe 2+ (aq)] were present alone, they were not utilized by the bacteria to degrade nitrate. According to the results of electrochemical analysis, adsorbed ferrous iron [Fe 2+ (ad)] on ferric oxides might be the electron donor in this kind of nitrate removal. [ABSTRACT FROM AUTHOR]

In China, the cadmium (Cd) levels in paddy fields have increased, which has led to the excessive uptake of Cd into rice grains. In this study, we determined the physicochemical properties of soil samples, including the pH, soil organic matter (SOM) content, cation exchange capacity (CEC), and total Cd content (Cd soil ) in order to establish a quadratic discriminant analysis (QDA) model for assessing the risk of Cd in rice and to calculate its prior probability. Decision tree and logistic regression models were also established for comparison. The results showed that the accuracy rate was 74% with QDA, which was significantly higher than that obtained using the decision tree (67%) and logistic regression (68%) models. The correlation coefficients between the soil pH and the other three factors (CEC, SOM, and Cd soil ) were higher in the inaccurate set than the accurate set, whereas the correlation coefficients were smaller in the inaccurate set than the accurate set. [ABSTRACT FROM AUTHOR]

Unlike languages where consonant duration is used contrastively to distinguish word meanings, long consonants in Mandarin Chinese only occur across morpheme boundaries as a result of concatenation and are referred to as fake geminates. To investigate whether Mandarin speakers employ duration contrast to differentiate fake Mandarin geminates and corresponding singletons as well as the underlying pattern of the processing, two auditory oddball tasks were carried out to measure the component of MMN, an index of the automatic detection of deviant stimulus. Mandarin pseudoword pairs which differ only in the duration of the medial consonant ([an1 an1] ∼ [an1 nan1] vs. [an2 an2] ∼ [an2 nan2]) were used as stimuli. An asymmetric pattern of brain activation was observed where the singleton deviant in the context of geminate words elicited higher MMNs than in the reversed condition. These findings are in line with earlier research suggesting that the singleton is unspecified for a moraic representation, while the geminate is specified. Mandarin speakers can employ duration contrast to distinguish fake geminates and corresponding singletons; furthermore, the processing of fake concatenated geminates in contrast to singletons is similar to that of real geminates and corresponding singletons. • Mandarin speakers use durational cues to differentiate fake geminate/singleton contrast. • The contrast is represented asymmetrically with a geminate specified for its length with a mora while a singleton is not. • Asymmetric processing pattern between fake geminate/singleton contrast was found for word pairs with different tones. [ABSTRACT FROM AUTHOR]