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1. chinaXiv:202005.00088 [pdf]

Effect of the W-beam central guardrails on wind-blown sand deposition on desert expressways in sandy regions

WANG Cui; LI Shengyu; LEI Jiaqiang; LI Zhinong; CHEN Jie
Subjects: Biology >> Botany >> Applied botany

Many desert expressways are affected by the deposition of the wind-blown sand, which might block the movement of vehicles or cause accidents. W-beam central guardrails, which are used to improve the safety of desert expressways, are thought to influence the deposition of the wind-blown sand, but this has yet not to be studied adequately. To address this issue, we conducted a wind tunnel test to simulate and explore how the W-beam central guardrails affect the airflow, the wind-blown sand flux and the deposition of the wind-blown sand on desert expressways in sandy regions. The subgrade model is 3.5 cm high and 80.0 cm wide, with a bank slope ratio of 1:3. The W-beam central guardrails model is 3.7 cm high, which included a 1.4-cm-high W-beam and a 2.3-cm-high stand column. The wind velocity was measured by using pitot-static tubes placed at nine different heights (1, 2, 3, 5, 7, 10, 15, 30 and 50 cm) above the floor of the chamber. The vertical distribution of the wind-blown sand flux in the wind tunnel was measured by using the sand sampler, which was sectioned into 20 intervals. In addition, we measured the wind-blown sand flux in the field at K50 of the Bachu-Shache desert expressway in the Taklimakan Desert on 11 May 2016, by using a customized 78-cm-high gradient sand sampler for the sand flux structure test. Obstruction by the subgrade leads to the formation of two weak wind zones located at the foot of the windward slope and at the leeward slope of the subgrade, and the wind velocity on the leeward side weakens significantly. The W-beam central guardrails decrease the leeward wind velocity, whereas the velocity increases through the bottom gaps and over the top of the W-beam central guardrails. The vertical distribution of the wind-blown sand flux measured by wind tunnel follows neither a power-law nor an exponential function when affected by either the subgrade or the W-beam central guardrails. At 0.0H and 0.5H (where H=3.5 cm, which is the height of the subgrade), the sand transport is less at the 3 cm height from the subgrade surface than at the 1 and 5 cm heights as a result of obstruction by the W-beam central guardrails, and the maximum sand transportation occurs at the 5 cm height affected by the subgrade surface. The average saltation height in the presence of the W-beam central guardrails is greater than the subgrade height. The field test shows that the sand deposits on the overtaking lane leeward of the W-beam central guardrails and that the thickness of the deposited sand is determined by the difference in the sand mass transported between the inlet and outlet points, which is consistent with the position of the minimum wind velocity in the wind tunnel test. The results of this study could help us to understand the hazards of the wind-blown sand onto subgrade with the W-beam central guardrails.

submitted time 2020-05-31 From cooperative journals:《Journal of Arid Land》 Hits8045Downloads435 Comment 0

2. chinaXiv:202005.00091 [pdf]

Crop production changes and the impact of Grain for Green program in the Loess Plateau of China

LYU Changhe; XU Zhiyuan
Subjects: Biology >> Botany >> Applied botany

Since the Grain for Green (GFG) program was implemented in 1999, most steeply sloping farmlands in the Loess Plateau of China have been returned to forestland and grassland. To understand its impact on the food production, this study analyzed the spatiotemporal changes of food crop production (FCP) in the plateau and quantified the contribution of sown area and yield changes to the total FCP during 1998–2014 using factor decomposition models, and then discussed the impact of GFG program on the FCP based on literature data. With the implementation of GFG program, total sown area in the Loess Plateau quickly deceased by 17.3% from 1998 to 2003, and then gradually restored to 1.03×107 hm2 in 2010. Thereafter, it slightly decreased to 1.02×107 hm2 (94.6% of the area in 1998) in 2014. By contrast, total FCP generally showed an apparent growth trend, averagely increased by 1.71% per year in the whole plateau during 1998–2014. This increase was jointly contributed by the improved yield of individual crops, and the adjustment of cropping structure, i.e., the expansion of high yield maize crop. The factor decomposition analysis results indicate that the sown area shrinkage only reduced the growth rate of total FCP by 0.29% per year during 1998–2014, although a significant impact was found for the early stage of 1999–2003. The results suggest that the implementation of GFG program would not induce an obvious risk of the food security. Therefore, it is suggested that the GFG program should be set as a long-term strategic policy, by not only supporting the conversion of slope farmlands, but also helping local farmers to seek sustainable ways of land use to improve the income and livelihood. It can be combined with the poverty eradication program, to simultaneously achieve the national goals of ecological civilization building and the livelihood improvement of rural people in the Loess Plateau. Considering rainfall limitation, the conversion of slope farmlands should be prioritized to grasslands.

submitted time 2020-05-31 From cooperative journals:《Journal of Arid Land》 Hits6529Downloads386 Comment 0

3. chinaXiv:202005.00096 [pdf]

Challenges for the sustainable use of water and land resources under a changing climate and increasing salinization in the Jizzakh irrigation zone of Uzbekistan

Rashid KULMATOV; Jasur MIRZAEV; Jilili ABUDUWAILI; Bakhtiyor KARIMOV
Subjects: Biology >> Botany >> Applied botany

Jizzakh Province in Uzbekistan is one of the largest irrigated areas in Central Asia without natural drainage. In combination with aridity, climate change and extensive irrigation practices, this has led to the widespread salinization of agricultural land. The aim of this study was to identify opportunities to improve the reclamation status of the irrigated area and how best to effectively use the water resources in Jizzakh Province based on investigations conducted between 1995 and 2016. A database of field measurements of groundwater levels, mineralization and soil salinity conducted by the provincial Hydro-Geological Reclamation Expeditions was used in the study. The total groundwater mineralization was determined using a portable electric conductometer (Progress 1T) and the chloride concentration was determined using the Mohr method. The soil salinity analyses were conducted by applying two different methods: (1) the extraction and assessment of the soluble salt content, and (2) using an SM-138 conductivity sensor applied to a 1:1 mixture of soil sample and water. The analyses of the monitoring results and the salt balance in the "irrigation water–soil–drainage water" system clearly demonstrated that the condition of the irrigated land in the province was not significantly improved. Under these conditions, the stability of crop yields is achieved mainly through the use of large volumes of fertilizer. However, excess amounts of mineral fertilizers can also cause the salinization of soils. The average groundwater salinization value in most of the irrigated land (75.3%) fluctuated between 1.1 and 5.0 g/L, while the values were less than 1.0 g/L in 13.1% of the land and in the range of 5.1–10.0 g/L in 10.5% of the land. During the period of 1995–2016 the salinization level of the irrigated land in Jizzakh Province increased slightly and the area could be divided into the following classes: no salinity (17.7% of the total area), low salinity (51.3%), moderate salinity (29.0%), and high salinity (2.0%). Detailed studies of the salt balance in irrigated land, the impact of climate change, increased fertilizer use, and repeated remediation leaching on the groundwater level and mineralization should be conducted in the future, due to the possibility of accelerated salinization, fertility decline, and reduced yields of agricultural crops.

submitted time 2020-05-31 From cooperative journals:《Journal of Arid Land》 Hits5043Downloads322 Comment 0

4. chinaXiv:202005.00098 [pdf]

Stable oxygen-hydrogen isotopes reveal water use strategies of Tamarix taklamakanensis in the Taklimakan Desert, China

DONG Zhengwu; LI Shengyuo; ZHAO Ying; LEI Jiaqiang; WANG Yongdong; LI Congjuan
Subjects: Biology >> Botany >> Applied botany

Tamarix taklamakanensis, a dominant species in the Taklimakan Desert of China, plays a crucial role in stabilizing sand dunes and maintaining regional ecosystem stability. This study aimed to determine the water use strategies of T. taklamakanensis in the Taklimakan Desert under a falling groundwater depth. Four typical T. taklamakanensis nabkha habitats (sandy desert of Tazhong site, saline desert-alluvial plain of Qiemo site, desert-oasis ecotone of Qira site and desert-oasis ecotone of Aral site) were selected with different climate, soil, groundwater and plant cover conditions. Stable isotope values of hydrogen and oxygen were measured for plant xylem water, soil water (soil depths within 0–500 cm), snowmelt water and groundwater in the different habitats. Four potential water sources for T. taklamakanensis, defined as shallow, middle and deep soil water, as well as groundwater, were investigated using a Bayesian isotope mixing model. It was found that groundwater in the Taklimakan Desert was not completely recharged by precipitation, but through the river runoff from snowmelt water in the nearby mountain ranges. The surface soil water content was quickly depleted by strong evaporation, groundwater depth was relatively shallow and the height of T. taklamakanensis nabkha was relatively low, thus T. taklamakanensis primarily utilized the middle (23%±1%) and deep (31%±5%) soil water ?and groundwater (36%±2%) within the sandy desert habitat. T. taklamakanensis mainly used the deep soil water (55%±4%) and a small amount of groundwater (25%±2%) within the saline desert-alluvial plain habitat, where the soil water content was relatively high and the groundwater depth was shallow. In contrast, within the desert-oasis ecotone in the Qira and Aral sites, T. taklamakanensis primarily utilized the deep soil water (35%±1% and 38%±2%, respectively) and may also use groundwater because the height of T. taklamakanensis nabkha was relatively high in these habitats and the soil water content was relatively low, which is associated with the reduced groundwater depth due to excessive water resource exploitation and utilization by surrounding cities. Consequently, T. taklamakanensis showed distinct water use strategies among the different habitats and primarily depended on the relatively stable water sources (deep soil water and groundwater), reflecting its adaptations to the different habitats in the arid desert environment. These findings improve our understanding on determining the water sources and water use strategies of T. taklamakanensis in the Taklimakan Desert.

submitted time 2020-05-31 From cooperative journals:《Journal of Arid Land》 Hits3281Downloads196 Comment 0

5. chinaXiv:202002.00081 [pdf]

SARS-coronavirus-2 nsp13 possesses NTPase and RNA helicase activities

Shu, Ting; Huang, Muhan; Wu, Di; Ren, Yujie; Zhang, Xueyi; Han, Yang; Mu, Jingfang; Wang, Ruibing; Qiu, Yang; Zhang, Ding-Yu; Zhou, Xi
Subjects: Biology >> Virology

The ongoing outbreak of Coronavirus Disease 2019 (COVID-19) has become a global pandemic and crisis. SARS-coronavirus-2 (SARS-CoV-2), the causative pathogen of COVID-19, is a positive-sense single-stranded RNA virus belonging to the family Coronaviridae. For RNA viruses, virus-encoded RNA helicases have long been recognized to play pivotal roles during viral life cycles by facilitating the correct folding and replication of viral RNAs. Here, our studies show that SARS-CoV-2-encoded nonstructural protein 13 (nsp13) possesses the nucleoside triphosphate hydrolase (NTPase) and RNA helicase activities that can hydrolyze all types of NTPs and unwind RNA helices dependently of the presence of NTP, and further characterize the biochemical characteristics of these two enzymatic activities associated with SARS-CoV-2 nsp13. Moreover, we found that some bismuth salts could effectively inhibit both the NTPase and RNA helicase activities of SARS-CoV-2 nsp13 in a dose-dependent manner. Thus, our findings demonstrate the NTPase and helicase activities of SARS-CoV-2 nsp13, which may play an important role in SARS-CoV-2 replication and serve as a target for antivirals.

submitted time 2020-04-19 Hits12922Downloads1313 Comment 0

6. chinaXiv:201908.00119 [pdf]

New gobiconodontid (Eutriconodonta, Mammalia) from?the Lower Cretaceous Shahai and Fuxin formations,?Liaoning, China

KUSUHASHI Nao; WANG Yuan-Qing; ?LI Chuan-Kui; JIN Xun
Subjects: Biology >> Zoology

Eutriconodontans are one of the key members of mammals to our understanding of the evolution and transition of mammalian fauna in Asia during the Cretaceous. Two gobiconodontid?and two triconodontid species have previously been reported from the upper Lower Cretaceous?Shahai and Fuxin formations. Here we describe two additional eutriconodontans from the?formations, Fuxinoconodon changi gen. et sp. nov. and ?Gobiconodontidae gen. et sp. indet.?This new species is attributed to the Gobiconodontidae, characterized by having an enlarged?first lower incisor, reduction in the number of incisors and premolariforms, proportionally large?cusps b and c being well distant from cusp a on the molariforms, presence of a labial cingulid,?and a unique mixed combination of molariform characters seen on either the first or the second,?but not both, generations of molariforms in Gobiconodon. Together with the four known species,?eutriconodontans remained diverse to some extent in the late Early Cretaceous in Asia, although?their family-level and generic level diversity appears to have been already reduced at that time.

submitted time 2019-08-26 From cooperative journals:《古脊椎动物学报》 Hits7159Downloads607 Comment 0

7. chinaXiv:201908.00120 [pdf]

New gobiconodontid (Eutriconodonta, Mammalia) from?the Lower Cretaceous Shahai and Fuxin formations,?Liaoning, China

KUSUHASHI Nao; WANG Yuan-Qing; ?LI Chuan-Kui; JIN Xun
Subjects: Biology >> Zoology

Eutriconodontans are one of the key members of mammals to our understanding of the evolution and transition of mammalian fauna in Asia during the Cretaceous. Two gobiconodontid?and two triconodontid species have previously been reported from the upper Lower Cretaceous?Shahai and Fuxin formations. Here we describe two additional eutriconodontans from the?formations, Fuxinoconodon changi gen. et sp. nov. and ?Gobiconodontidae gen. et sp. indet.?This new species is attributed to the Gobiconodontidae, characterized by having an enlarged?first lower incisor, reduction in the number of incisors and premolariforms, proportionally large?cusps b and c being well distant from cusp a on the molariforms, presence of a labial cingulid,?and a unique mixed combination of molariform characters seen on either the first or the second,?but not both, generations of molariforms in Gobiconodon. Together with the four known species,?eutriconodontans remained diverse to some extent in the late Early Cretaceous in Asia, although?their family-level and generic level diversity appears to have been already reduced at that time.

submitted time 2019-08-26 From cooperative journals:《古脊椎动物学报》 Hits7297Downloads589 Comment 0

8. chinaXiv:201811.00111 [pdf]

Microbial adaptation to long-term N supply prevents large responses in N dynamics and N losses of a subtropical forest

Han, Xiaodge; Shen, Weijun; Zhang, Jinbo; Muller, Christoph
Subjects: Biology >> Biochemistry

Atmospherically-deposited nitrogen (N) can stimulate complex soil N metabolisms and accumulations over time. Whether long-term (decadal) N deposition effects on soil N transformations and functional microbes differ from the short-term (annual) effects have rarely been assessed. Here we conducted a laboratory 15N tracing study with soil samples from a short-term (one year) N addition site and a long-term (12 years) site in a subtropical forest. The effects of simulated N deposition on soil N2O emissions, N transformation rates and microbial nitrifying and denitrifying genes were determined. Our results showed that: (1) long-term N addition did not change soil N2O fluxes significantly in comparison to the short-term N addition. Denitrification, heterotrophic nitrification and autotrophic nitrification contributed 53%, 23% and 18% to total N2O emissions, respectively. (2) Autotrophic nitrification was the dominant N transformation process, except for the high-N treatment at the long-term site. The magnitude of soil N transformation rates was significantly different among N addition treatments but not between short- and long-term N addition sites. However, long-term N addition changed the responses of specific N transformation rates to N addition markedly, especially for the rates of nitrification, organic N mineralization to NH4+, NO3- immobilization and dissimilatory NO3- reduction to NH4+ (DNRA). (3) Responses of ammonia oxidizing archaea and bacteria (AOA and AOB) were stronger than denitrifying N2O-producers (nirK) and denitrifying N2O-reducers (nosZ) at the long-term site compared to the short-term site. (4) The close correlations among N2O flux, functional genes and soil properties observed at the short-term site was weakened at the long-term site, posing a decreased risk for N losses in the acid subtropical forest soils. There is evidence for an adaptation of functional microbial communities to the prevailing soil conditions and in response to long-term natural and anthropogenic N depositions.

submitted time 2018-11-22 Hits1542Downloads787 Comment 0

9. chinaXiv:201801.00265 [pdf]

Maximized photosynthetic capacity and decreased hydraulic failure risk during aging in the clump bamboo, Bambusa chungii

Zhang, Zhenzhen; Zhou, Juan; Zhao, Xiuhua; Zhao, Ping; Zhu, Liwei; Ouyang, Lei; Ni, Guangyan
Subjects: Biology >> Botany

To assess the water use of a clumped bamboo species, we investigated water use, physiological responses, and structural changes related to culm aging in the clumped bamboo species Bambusa chungii. Anisohydric behavior was characterized by the changed leaf water potential (ΨL), constant stomatal conductance (gs), and the low stomatal sensitivity (–m) in the young (0.52) and mature groups as well as the aged group (0.41). Intercellular CO2 (Ci) was negatively related to gs, especially during the dry season (R2 = 0.62). Hydraulic conductivity (ks) decreased by 57.9% and 58.8% in the mature and aged groups. This was accompanied by a leaf area (AL) that decreased by 55.7% and 63.7% and water transport path (h) that shortened by 8.5% and 23.3% to maintain the hydraulic safety. The photosynthetic rate (An) was similar among the three age groups even during the dry season when water deficits occurred. This might be due to compensation by increased chlorophyll content (5.3% greater for the mature group) and stomata density (7.4% and 8.1% greater for the mature and aged groups). Physiological and structural regulation contributes to reproductive success for B. chungii.

submitted time 2018-01-13 Hits840Downloads483 Comment 0

10. chinaXiv:201711.01916 [pdf]

Early Mammut from the Upper Miocene of northern China, and its implications for the evolution and differentiation of Mammutidae

WANG Shi-Qi; LI Yu; Jaroon DUANGKRAYOM; CHEN Shao-Kun; HE WenCHEN Shan-Qin
Subjects: Biology >> Zoology

Mammut is the terminal taxon of the proboscidean group Mammutidae, which survived to the Late Pleistocene. Although this genus was widely distributed in the Pliocene of Eurasia and the Pleistocene of North America, little is known about its early evolution. Here, we report on Mammut cf. M. obliquelophus from the Upper Miocene of northern China based on new fossil material, including an almost complete juvenile cranium and other remains, which show many primitive features within Mammutidae and clearly demonstrate the morphological evolution of Mammut. The strongly laterally expanded lateral wing of the occiput and the presence of basal constriction of the incisive fossa display cranial similarity between Mammut cf. M. obliquelophus and both Eozygodon morotoensis and Choerolophodon guangheensis, early representatives of the Mammutidae and Choerolophodontidae, respectively, indicating the close relationship between these two groups: both of them are located at the basal phylogenetic positions in Elephantimorpha. This result is further confirmed by a cladistic analysis.

submitted time 2017-11-07 From cooperative journals:《古脊椎动物学报》 Hits1046Downloads589 Comment 0

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