Assessment and prediction of shoreline change using multi-temporal satellite images and statistics: Case study of Damietta coast,Egypt

The shoreline trajectory of Damietta city, locates at the Northern coast of Egypt, is dramatically subjected to kinematic changes. These variations mainly occur based on the incessant duel hydrodynamic impacts of both wave action and coastal currents. Several types of coastal measures have been applied substantially along the coastal stretch of Damietta to protect shoreline such as detached breakwaters, Jetties, groins, and seawalls. This study is essentially focused on the assessment of shoreline kinematics response due to the existence of these structures during the period from 1990 to 2015. In addition, the future changes of the shoreline at 2020, 2025 and 2035 are predicted using satellite images, Geo-spatial tools and Digital Shoreline Analysis System (DSAS) by the meaning of End Point Rate (EPR) and Linear Regression Rate (LRR) methods. Four Landsat images at different periods; TM1990, TM 1999, ETM 2003 and ETM 2015 are used to detect shoreline changes. Three semi-automatic extraction techniques are initially tempted for Landsat ETM 2003 imagery namely; Iso cluster technique, threshold method, and onscreen digitizing method to select the optimal one. Iso cluster technique is used as the optimal technique which achieves the least errors with the corresponding field data in 2003 by value of 0.34. Furthermore, the extraction shoreline change for Damietta coast is extensively measured for three zones: zone (1) the western sector encompassing Damietta port with two jetties; zone (2) the central sector including detached breakwaters; zone (3) the eastern portion of Damietta estuary passing through a seawall. Verification analysis shows that the EPR is the optimum method for shoreline detection with a value of RMSE by 0.27. The results show that, for zone (1), the western shoreline of Damietta port is progressed by a rate of +10.0 m/year. On the other hand, the shoreline on the down drift side at zone (2) has retreated by a rate of -5.0 m/year. While the shoreline behind the detached breakwaters in the central sector has advanced by +12.0 m/year from 1999 to 2003, then decreased gradually until become stable in 2015. For zone (3), alongshore currents have derived the disassembled sandy soil from west to east leaving a highly eroded area by average rate of -78m/year. The results of this study give indication to shoreline trend of near future which should be under consideration in planning of Damietta coastal zone.     

河北张家口金矿床石英的电子顺磁共振谱（EPR）研究

本文对采自河北张家口金矿床中不同种类、不同金含量的石英在不同的温度条件（Ｔ＝３００Ｋ，常温；Ｔ＝７２Ｋ，低温、液氮）下进行电子顺磁共振谱（ＥＰＲ）研究表明：①石英中顺磁中心的浓度随温度变化而变化，即随温度的降低，石英中顺磁中心的浓度将增大；②不同温度条件下，石英ＥＰＲ谱国中吸收峰的差异仅体现在吸收强度上，形态上的差异不很明显；③石英中金含量与其ＥＰＲ谱图中吸收峰的强度之间存在着统计性的正相关关系；④石英中含有部分离子态的金──晶格金。     

菲对斜生栅藻(Scenedesmus obliquus)自由基的诱导及胁迫效应

通过静态模拟实验,研究不同浓度(0.005、0.01、0.025、0.05和0.1 mg/L)菲暴露96 h后,对斜生栅藻的生长、自由基含量、抗氧化系统以及脂质过氧化产物(MDA)的影响.结果表明,0.01 mg/L菲开始对藻细胞生长产生显著抑制作用,在此浓度下电子自旋共振检测到的自由基信号(g=2.0033,幅宽10.15 mT)显著增强;在浓度设置范围内,超氧化物酶歧化酶、过氧化物酶、谷胱甘肽-S-转移酶活性均被显著诱导,显示出抗氧化系统的应激机制.谷胱甘肽和MDA含量均在0.025 mg/L时被显著诱导.这说明斜生栅藻对菲暴露比较敏感,0.01 mg/L即已显示胁迫效应,自由基的诱导是斜生栅藻产生损伤的重要原因,藻细胞的生长量是比较敏感的损伤指标.     

热处理低温钠长石的EPR和X射线衍射研究

利用电子顺磁共振(EPR)和X射线衍射方法研究了天然和热处理钠长石单晶。热处理在500—850℃水热条件下完成。在外加磁场B平行于晶体c~*轴的方向上,测量了加热前后Fe~(3+)的EPR谱和线宽△B随温度和加热时间的变化。结果显示,线宽随Al、Si无序的增大而增加。由此得出结论,在低温钠长石中,Fe~(3+)位于Al~(3+)占据的T_1(o)位置,在被研究的温度范围内,Fe~(3+)未参与四面体位置T间Al、Si交换。谱线的加宽主要是由在Fe~(3+)邻近位置上Al、Si无序的增大引起的,同时与观测到的晶胞参数变化有关。在Al、Si无序更强的晶体中,Fe~(3+)谱变得极宽。     

Color centers in topaz: comparison between neutron and gamma irradiation

Neutron- and gamma irradiation-induced paramagnetic centers in natural colorless topaz from four different Brazilian localities were studied by electron paramagnetic resonance (EPR) and optical absorption as a function of irradiation dose and thermal treatment. Gamma irradiation doses were applied up to 1,000 kGy with a dose rate of 15 kGy h⁻¹. For the neutron irradiation experiments, a neutron flux of 4 × 10¹² cm⁻² s⁻¹ was used with an integrated flux of up to 1 × 10¹⁸ cm⁻². From the experiments, it is concluded that brownish colors are induced by gamma-rays and may be associated with a single broad isotropic EPR line with g = 2.015(2). Both the EPR line and the related optical absorption band at 460 nm (2.7 eV) are lost during thermal treatments between 150 and 200°C. Fast neutrons create the paramagnetic peroxyl radicals O₂ ⁻ and the paramagnetic O⁻ hole centers. The O⁻ centers have the same thermal stability as the optical absorption band at 620 nm (2.0 eV). It is confirmed that the absorption due to the O⁻ center is responsible for the blue color in topaz. Both color centers and their absorption bands are discussed in the context of O⁻ bound small polarons.     

Correlation of irradiation-induced yellow color with the O<Superscript>−</Superscript> hole center in tourmaline

Tourmaline with the general formula XY₃Z₆(BO₃)₃Si₆O₁₈(OH,O)₃(OH,F) and the trigonal space group R3m (C_3v⁵) is known as a gemstone with great variety of colors. Some color centers are related to transition metal ions, and others to electron or hole traps. In this paper we report on a combined study using electron paramagnetic resonance (EPR), electron nuclear double resonance (ENDOR), and the optical detection of EPR (ODEPR) on a yellow color center produced by -irradiation in colorless Li-bearing elbaite tourmaline from Brazil. The color center is an O^– hole trap center, which is stabilized within the plane spanned by three Y sites, and is located in the structural channels formed by Si₆O₁₈. We suggest that two of the Y sites are substituted by ²⁷Al and the other by ^6,7Li. During the irradiation process atomic hydrogen H⁰ is also produced, which shows the same thermal stability as the hole center (250 °C). Therefore, we assign H⁰ to be the local charge compensator for the hole trap. From the ODEPR measurements we conclude that the yellow color is caused by the O^– hole center. The large negative isotropic Al superhyperfine interaction of the O^– hole trap center is consistent with a calculation of the transferred hyperfine interactions by exchange polarization supporting the proposed defect model of an O^– at the O₁ sites, whereby the O^– is relaxed into the plane formed by three Y ions.     

方镁石中Cr^3＋—空位中心附近的局部压缩率

用晶体场理论研究了方镁石中Cr~(3+)离子的零场劈裂D随单轴压力的变化,发现杂质离子附近的局部压缩率的确不同于基质晶体的压缩率,即由于Cr~(3+)离子附近有阳离子空位出现,空位附近的氧离子将更易于向空位压缩,造成局部压缩率不同于基质晶体压缩率。     

The unusual magnetic properties of kuramite–stannite pseudobinary series: a SQUID and EPR survey

The magnetic properties of the synthetic Cu₃SnS₄ (kuramite)–Cu₂FeSnS₄ (stannite) pseudobinary series were investigated by means of electron paramagnetic resonance (EPR) spectroscopy, at room temperature, and by magnetometry, in the range 2–300 K. The system is particularly complex, from both chemical and crystal chemical points of view, in particular with respect to the metal valence states and the local ordering in the different terms of the series. Nevertheless, recent successes in synthesising nanostructured kuramite foster the interest to ascertain the bulk magnetic properties of these important semiconducting phases. The obtained results allowed to ascertain that a variable lack of local ordering in the Cu_3–x Fe _x SnS₄ (x < 0.85) samples induce the raise of strong metal–sulphur–metal superexchange interactions, that result in the appearance of marked deviations from the single-ion behaviour, typical for pure stannite. Ferro- and antiferromagnetic interactions are in fact observed at relatively high temperatures (~150 K). A possible role played by Cu(I)–Fe(III) was revealed by the EPR measurements. The Cu-rich terms of the series (x < 0.1) are characterised by dynamic resonant disorder (i.e. time-evolving delocalisation of the formally divalent valence state for Cu among the nearest neighbouring Cu-sites), in addition to the Cu–Fe–Sn static disorder verified along the whole series. Both factors concurring to a non-periodic arrangement of paramagnetic ions in the lattice have the main effect to drastically broaden the EPR lines.     

The distribution of Cu(II) and the magnetic properties of the synthetic analogue of tetrahedrite: Cu12Sb4S13

A wide investigation of the synthetic analogue of tetrahedrite, Cu₁₂Sb₄S₁₃, has been performed by a combination of several techniques, magnetisation and differential scanning calorimetric measurements, cw, and pulsed EPR spectroscopy, to obtain complementary information about the presence and the distribution of Cu(II). The high temperature susceptibility of the sample accounts for two Cu(II) per formula unit, in agreement with the charge balance. However, strong antiferromagnetic interactions, observed even at room temperature, are associated with a transition at 83(3) K. At lower temperatures a residual susceptibility is observed. At 4.2 K ESEEM experiments enabled observation of the chemical environment of the residual paramagnetic species. Cu(II) was found randomly distributed in the M(1) site. The statistical presence of nearest neighbouring Cu(II) ions justify the observed antiferromagnetic interactions and transition. Nevertheless, isolated paramagnetic ions have been determined below the Néel temperature: they are mainly located near the surface of the grains. A colour centre, previously observed in natural samples, has been also identified.