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101.
102.
Daniela Comelli Massimo D'orazio Luigi Folco Mahmud El‐Halwagy Tommaso Frizzi Roberto Alberti Valentina Capogrosso Abdelrazek Elnaggar Hala Hassan Austin Nevin Franco Porcelli Mohamed G. Rashed Gianluca Valentini 《Meteoritics & planetary science》2016,51(7):1301-1309
Scholars have long discussed the introduction and spread of iron metallurgy in different civilizations. The sporadic use of iron has been reported in the Eastern Mediterranean area from the late Neolithic period to the Bronze Age. Despite the rare existence of smelted iron, it is generally assumed that early iron objects were produced from meteoritic iron. Nevertheless, the methods of working the metal, its use, and diffusion are contentious issues compromised by lack of detailed analysis. Since its discovery in 1925, the meteoritic origin of the iron dagger blade from the sarcophagus of the ancient Egyptian King Tutankhamun (14th C. BCE) has been the subject of debate and previous analyses yielded controversial results. We show that the composition of the blade (Fe plus 10.8 wt% Ni and 0.58 wt% Co), accurately determined through portable x‐ray fluorescence spectrometry, strongly supports its meteoritic origin. In agreement with recent results of metallographic analysis of ancient iron artifacts from Gerzeh, our study confirms that ancient Egyptians attributed great value to meteoritic iron for the production of precious objects. Moreover, the high manufacturing quality of Tutankhamun's dagger blade, in comparison with other simple‐shaped meteoritic iron artifacts, suggests a significant mastery of ironworking in Tutankhamun's time. 相似文献
103.
利用实时探空场和欧洲中心20:00细网格、NCEP再分析资料对2013年8月6—10日杭州湾北岸极端高温过程进行分析,结果表明:副高脊线稳定在30°N、高层有辐散气流、低层26℃暖气团处于强副高中心影响是持续40℃极端高温发生的大尺度环流背景。副高与南亚高压"相向而行",在垂直方向上产生深厚的次级环流圈,是2013年极端高温持续时间长、影响范围大的一个重要因素。极端高温的出现与空气异常干燥有密切关系,北方高层干空气南下叠加在中低层副高暖干气团之上,从高层到近地层受一致下沉气流的绝热压缩增温,以及低空暖平流输送的综合影响,是导致7—9日杭州湾北岸多地最高气温屡破记录的原因。经检验,极端高温期间,业务参考使用的4个主要数值模式对最高气温的预报,EC模式误差较小且稳定,绝对误差为1℃,而GFS、JMA和T639误差分别达3℃、4℃和5℃,应用时需订正,以上结果可供夏季高温预报参考。 相似文献
104.
Ahmad Rami El-Nabulsi 《中国天文和天体物理学报》2011,(8)
We explore a 5D Brans-Dicke scalar cosmology by conjecturing that the four-dimensional Hubble parameter varies as H = εφs,ε∈ R and s is some unknown power index and that the extra-dimensions compactify as the visible dimensions expand as b(t) ≈ ax(t) ,x ∈ R-. We mainly discuss the case x =-1. For critical values of ε close to unity,it was observed that the acceleration of the universe occurs at redshift close to z = 0.8 which indicates that in our model,accelerated expansion of the universe began only recen... 相似文献
105.
Ahmad Rami El-Nabulsi 《Astrophysics and Space Science》2011,332(1):37-42
We investigate the late-time dynamics of a four-dimensional universe based on the effective action of a Brans-Dicke scalar
field in the presence of the matter source term, conformal coupling of the scalar curvature to the scalar field, a dynamical
cosmological constant and Gauss-Bonnet higher-order terms in the scalar curvature. Many new interesting features are revealed
and discussed in some details. 相似文献
106.
Finding a coupling model between a hydraulic parameter such as permeability and a mechanical parameter such as damage is the key element for several recent engineering problems. A review of the technical literature reveals that several mechanical constitutive laws exist which allow determining a damage tensor for a damageable porous material under loading. But the present work develops a method to deduce the permeability change due to the damage propagation. 相似文献
107.
Artificial groundwater recharge to a semi-arid basin: case study of Mujib aquifer,Jordan 总被引:1,自引:1,他引:0
Mujib watershed is an important groundwater basin which is considered a major source for drinking and irrigation water in
Jordan. Increased dependence on groundwater needs improved aquifer management with respect to understanding deeply recharge
and discharge issues, planning rates withdrawal, and facing water quality problems arising from industrial and agricultural
contamination. The efficient management of this source depends on reliable estimates of the recharge to groundwater and is
needed in order to protect Mujib basin from depletion. Artificial groundwater recharge was investigated in this study as one
of the important options to face water scarcity and to improve groundwater storage in the aquifer. A groundwater model based
on the MODFLOW program, calibrated under both steady- and unsteady-state conditions, was used to investigate different groundwater
management scenarios that aim at protecting the Mujib basin. The scenarios include variations of abstraction levels combined
with different artificial groundwater recharge quantities. The possibilities of artificial groundwater recharge from existing
and proposed dams as well as reclaimed municipal wastewater were investigated. Artificial recharge options considered in this
study are mainly through injecting water directly to the aquifer and through infiltration from reservoir. Three scenarios
were performed to predict the aquifer system response under different artificial recharge options (low, moderate, and high)
which then compared with no action (recharge) scenario. The best scenario that provides a good recovery for the groundwater
table and that can be feasible is founded to be by reducing current abstraction rates by 20% and implementing the moderate
artificial recharge rates of 26 million(M)m3/year. The model constructed in this study helps decision makers and planners in selecting optimum management schemes suitable
for such arid and semi-arid regions. 相似文献
108.
Effects of natural and calcined oyster shells on Cd and Pb immobilization in contaminated soils 总被引:5,自引:0,他引:5
Yong Sik Ok Sang-Eun Oh Mahtab Ahmad Seunghun Hyun Kwon-Rae Kim Deok Hyun Moon Sang Soo Lee Kyoung Jae Lim Weon-Tai Jeon Jae E. Yang 《Environmental Earth Sciences》2010,61(6):1301-1308
In Korea, soils adjacent to abandoned mines are commonly contaminated by heavy metals present in mine tailings. Further, the
disposal of oyster shell waste by oyster farm industries has been associated with serious environmental problems. In this
study, we attempted to remediate cadmium (Cd)- and lead (Pb)-contaminated soils typical of those commonly found adjacent to
abandoned mines using oyster shell waste as a soil stabilizer. Natural oyster shell powder (NOSP) and calcined oyster shell
powder (COSP) were applied as soil amendments to immobilize Cd and Pb. The primary components of NOSP and COSP are calcium
carbonate (CaCO3) and calcium oxide (CaO), respectively. X-ray diffraction, X-ray fluorescence and scanning electron microscope analyses conducted
in this study revealed that the calcination of NOSP at 770°C converted the less reactive CaCO3 to the more reactive CaO. The calcination process also decreased the sodium content in COSP, indicating that it was advantageous
to use COSP as a liming material in agricultural soil. After 30 days of incubation, we found that the 0.1 N HCl-extractable
Cd and Pb contents in soil decreased significantly as a result of an increase in the soil pH and the formation of metal hydroxides.
COSP was more effective in immobilizing Cd and Pb in the contaminated soil than NOSP. Overall, the results of this study suggest
that oyster shell waste can be recycled into an effective soil ameliorant. 相似文献
109.
Rancher and farmer perceptions of climate change in Nevada, USA 总被引:1,自引:1,他引:0
Farming and ranching communities in arid lands are vulnerable to the adverse impacts of climate change. We surveyed Nevada ranchers and farmers (n?=?481) during 2009–2010 to assess climate change related knowledge, assumptions, and perceptions. The large majority of this group agreed that we are in a period of climate change; however, only 29 % of them believed that human activity is playing a significant role. Female ranchers and farmers hold more scientifically accurate knowledge about climate change than do their male counterparts, regardless of Democratic or Republican affiliation. Partisan affiliation, political ideology, and gender have strong impacts on climate change knowledge and perceptions. Republican, conservative and male rural residents view climate change as a low national priority, less important to themselves, and less harmful to their communities. Female ranchers and farmers are more concerned about the negative impacts of climate change. We found that only 4 % of our subjects (n?=?299) attribute local environment changes to climate change or global warming. The knowledge gained from this study will help researchers and natural resource managers understand how to best communicate about climate change with rural communities, and support policy makers in identifying potentially effective adaptation and mitigation policies and outreach programs. 相似文献
110.
Effects of biochar, cow bone, and eggshell on Pb availability to maize in contaminated soil irrigated with saline water 总被引:2,自引:0,他引:2
Yaser A. Almaroai Adel R. A. Usman Mahtab Ahmad Deok Hyun Moon Ju-Sik Cho Young Kyoo Joo Choong Jeon Sang Soo Lee Yong Sik Ok 《Environmental Earth Sciences》2014,71(3):1289-1296
Toxicity of heavy metals adversely affects environment and human health. Organic materials derived from natural matters or wastes have been applied to soils to reduce the mobility of contaminants such as heavy metals. However, the application of cow bone powder (CB), biochar (BC), and eggshell powder (ES) is rarely investigated for the reduction of Pb bioavailability in soils irrigated with saline water. The objective of this study was to assess the effectiveness of CB, BC, and ES additions as immobilizing substances on Pb bioavailability in shooting range soil irrigated with deionized and saline water. Each additive of CB, BC, and ES at 5 % (w/w) was mixed with soils and then the deionized and saline water were irrigated for 21 days. With deionized water irrigation, the soils treated with CB, BC, and ES exhibited higher pH when compared with saline water irrigation. With saline water irrigation, the electrical conductivity, water-soluble anions, and cations were significantly increased in soils treated with CB, BC, and ES. The water-soluble Pb in soils treated with CB, BC, and ES was significantly decreased with saline water irrigation. On the other hand, the water-soluble Pb in soil treated with CB was increased with deionized water irrigation. Only BC with saline water irrigation decreased the Pb concentration in maize shoots. 相似文献