Low Reflectance Values Research Articles

Chronology of deposition and unconformity development across the Cretaceous–Paleogene boundary, Magallanes-Austral Basin, Patagonian Andes

The Magallanes-Austral foreland basin preserves an important record of orogenesis and landscape evolution in the Patagonian Andes of Chile and Argentina. Throughout the retroarc foreland basin, a regional disconformity with little to no angular discordance separates Upper Cretaceous–lower Paleocene strata from overlying deposits of diachronous Eocene to Miocene age. Here we report detrital zircon U-Pb geochronological results for 11 sandstone samples, and vitrinite reflectance data for 6 samples of organic matter from a fossiliferous dinosaur-bearing mixed nonmarine and marine clastic succession in the Río de las Chinas valley (50–51°S) of central-southern Patagonia to: (1) determine the timing and duration of the unconformity using U-Pb maximum depositional age constraints, (2) reconstruct sediment provenance and dispersal patterns, (3) assess possible temporal variations in arc magmatism, (4) evaluate the amount of sedimentary overburden removed during unconformity development, and (5) confirm the presence of a fossiliferous southern hemisphere Cretaceous–Paleogene (K/Pg) boundary site. Samples from the Dorotea Formation yield maximum depositional ages spanning Maastrichtian to Danian time (with ages as young as ∼65–63 Ma), confirming preservation of the K/Pg boundary in a section with recently discovered fossils of dinosaurs, other terrestrial vertebrates, and plants. Samples from directly above the unconformity in the Man Aike Formation, yield middle Eocene maximum depositional ages (with a prominent 45–40 Ma age cluster), indicating a long-lived ∼20 Myr hiatus representative of nondeposition or erosion. Analyses of organic matter preserved in multiple coal horizons of the uppermost Dorotea Formation show consistently low vitrinite reflectance values, requiring limited sedimentary burial, consistent with nondeposition or sediment bypass rather than deposition and later erosional removal of a previously proposed thick package of Paleocene to middle Eocene clastic material. On the basis of regional trends in the age and geometry of the unconformity, timing of arc magmatism, and temporal variations in sediment provenance, we consider a range of potential mechanisms for unconformity genesis, including (1) shortening-related uplift of the frontal fold-thrust belt, (2) cratonward advance of a flexural forebulge, (3) accommodation changes driven by regional or eustatic variations in sea level, (4) ridge collision and slab-window genesis, (5) isostatic rebound during tectonic quiescence (or minor extension), or (6) regional foreland uplift during flat-slab subduction.

Properties of solid bitumen and other organic matter from Oligocene shales of the Fore-Magura Unit in Polish Outer Carpathians: Microscopic and geochemical approach

In this study, we apply microscopic and geochemical (Rock-Eval) methods to evaluation of both the origin and maturity of solid bitumen and other organic matter dispersed in Oligocene shales from the Skrzydlna Tectonic Bay and the Mszana Dolna Tectonic Window of the Fore Magura Unit, Outer Carpathians, Poland. Homogenous solid bitumen occurs in early mature and mature samples of rocks from the Skrzydlna Tectonic Bay (vitrinite reflectance VR from 0.60 to 0.80%). It reaches reflectance values (BR) from 0.31 to 0.61% and is interpreted as the intermediate product between kerogen and oil originated during the oil generation process. In the late mature and post-mature samples from the Mszana Dolna Tectonic Window (VR from 1.10 to 1.49%), homogenous solid bitumen reflectance varies from 1.45 to 1.76%. This is an indigenous, thermally altered solid bitumen or residue after hydrocarbon generation, hence, it should be called the pyrobitumen. In samples from both locations, granular solid bitumen was found, as well, of reflectance values (GBR) from 0.25 to 0.92%.A very strong correlation of homogenous solid bitumen, pyrobitumen and granular solid bitumen reflectances with vitrinite reflectance was found in studied samples. When measured in the same sample, the solid bitumen from the Skrzydlna Tectonic Bay always showed lower reflectance values than the coexisting vitrinite. In samples from the Mszana Dolna Tectonic Window, in which measured vitrinite reflectance VR was always above 1,0%, the, observed pyrobitumen invariably showed the higher reflectance values whereas the granular solid bitumen consistently revealed lower reflectance than vitrinite, homogenous solid bitumen or pyrobitumen coexisting in the same sample. The Rock-Eval analyses confirmed that bitumen is indigenous in all studied samples. The degree of thermal maturation of organic matter based on vitrinite reflectance measurements was equivalent to organic matter maturity determined by the Rock-Eval Tmax values, which could be confirmation that our microscopic observations and selection of vitrinite fragments were correct.We were able to perform more individual measurements of homogenous solid bitumen particles and we obtained lower average standard deviation for BR values than for VR values. Due to the dark vitrinite abundant in samples taken in the Skrzydlna Tectonic Bay and the small-size vitrinite particles seen in samples from the Mszana Dolna Tectonic Window we found it difficult to select proper vitrinite particles for microscopic examinations. By contrast, both the solid bitumen and the pyrobitumen particles were often easier to recognize due to their characteristic shape and larger size than those of vitrinite fragments. For these set of samples we conclude that reflectance measurements run on homogenous solid bitumen are more reliable in comparison with those performed on vitrinite.

بإستخدام المحلل الشبكي Ca1-xNixFe2O4 دراسة الخصائص الكهربائية والمغناطسية والإمتصاصية لفيرايت السبينل نوع

In this work, the spinal ferrite has been prepared where , used. as radar absorbing materials (RAM). Conventional ceramic techniques method was used to prepare these materials at microwaves with the range of frequencies (8-12) GHz. The absorption for microwaves was examined by the utilized the network analyzer. The relationship between reflectivity, absorption and attenuation coefficient were plotted as a function of frequency, and sintered at a temperature . The results showed the emergence of several resonance peaks at , samples showed high Absorbency in contrast low reflectivity and high values of attenuation coefficient at the same frequencies, this is due to domain rotation as well domain wall motion of the ferrite. The values of the real and imaginary parts of relative magnetic Permeability and relative electric permittivity were measure for all samples. The results revealed the apparent resonance peaks at same frequencies that apparent at absorption and reflectivity curves of the same samples. X-ray diffraction tests were made for one sample and result showed the structure of the sample is polycrystalline. في.هذا البحث تحضير سلسلة من فيرايت السبينل نوع حيث تأخذ القيم بزيادة مقدارها كمواد ماصة للأشعة الرادارية. تم إستخدام الطريقة السيراميكية التقليدية في تحضير العينات والتي تم تلبيدها بدرجة حرارة واحدة درست إم تصاصية العينات ضمن النطاق السيني حيث مدى التردد بإستخدام جهاز المحلل الشبكي. رسمت العلاقة بين ألإمتصاصية، الإنعكاسية، معامل التوهين، النفاذية المغناطيسية و السماحية الكهربائية كدوال للتردد عند النطاق السيني. بينت النتائج ظهور عدة قمم رنينية عند ترددات النطاق السيني, أظهرت العينات إمتصاصية عالية وقيم معامل التوهين عالية في المقابل إنعكاسية قليلة والسبب هو دوران الحقل المغناطيسي نتيجة حركة جدار الحقل المغناطيسي للفيرايت. من قياسات النفاذية المغناطيسية وثابت العزل وضحت النتائج وجود القمم الرنينية عند نفس الترددات التي ظهرت عند منحنيات الإمتصاصية والإنعكاسية. تم فحص حيود الأشعة السينية للعينة حيث أظهرت النتائج أن تركيب العينة هو متعدد التبلور.

Petrographical and Chemical Properties of Mus Coals

One of the most important natural energy resources of our country stands to be as coal; our reserve with the newly discovered bed exceeds more than 14 billion tons. Although the higher quality coals are located at the western and inner part of Anatolia, there are some coal beds in the eastern Anatolia as well. The coals near Muş city are one of them. The coals are Tertiary (Pliocene) aged coals. Petrographical and chemical properties, as moisture, volatile matter, fixed carbon, ash content of the coals were determined in this study. The coals are of many thin layers and of a total thickness varying between 0.9-3.6 meters. The original coals contain of an average lower calorific value about 1200 Kcal/kg. Their ash content changes between 17-30 %, moisture with 30% average. The coals exhibit higher moisture content which is thought to be derived from high ground water level and of surfical water inputs. The dominant maceral of the coals is huminite, changing between 28 to 61 % amount. Gelinite is the most common huminites. Liptinite content changes between 2-5% and inertinite, between 2-11 %. The huminite reflectance (Ro) were measured as changing between 0.10 - 0.29 % (standard deviation as 0.01 - 0.02%) and corresponds to lignite rank. The low reflectance values are probably resulted from their shallow burials and their being remote to tectonic activities in the region. The coals comprise of 3-6% pyrite and 14-62 clay and other inorganic materials. Muş coals were classified as poor quality lignite, based on organic petrography, coal quality data and their low maturity index. Detail coal petrographical analysis seems to indicate depositional environment of the coals to be as limnic swamps. Total reserve of the coals is about 6.2 million metric tons.

A NOVEL METHOD FOR WATER AND WATER CANAL EXTRACTION FROM LANDSAT-8 OLI IMAGERY

Abstract. Constituents of hydrologic network, River and water canals play a key role in Agriculture for cultivation, Industrial activities and urban planning. Remote sensing images can be effectively used for water canal extraction, which significantly improves the accuracy and reduces the cost involved in mapping using conventional means. Using remote sensing data, the water Index (WI), Normalized Difference Water Index (NDWI) and Modified NDWI (MNDWI) are used in extracting the water bodies. These techniques are aimed at water body detection and need to be complemented with additional information for the extraction of complete water canal networks. The proposed index MNDWI-2 is able to find the water bodies and water canals as well from the Landsat-8 OLI imagery and is based on the SWIR2 band. In this paper, we use Level-1 precision terrain corrected OLI imagery at 30 meter spatial resolution. The proposed MNDWI-2 index is derived using SWIR2 (B7) band and Green (B3) band. The usage of SWIR2 band over SWIR1 results in very low reflectance values for water features, detection of shallow water and delineation of water features with rest of the features in the image. The computed MNDWI-2 index values are threshold by making the values greater than zero as 1 and less than zero as zero. The binarised values of 1 represent the water bodies and 0 represent the non-water body. This normalized index detects the water bodies and canals as well as vegetation which appears in the form of noise. The vegetation from the MNDWI-2 image is removed by using the NDVI index, which is calculated using the Top of Atmosphere (TOA) corrected images. The paper presents the results of water canal extraction in comparison with the major available indexes. The proposed index can be used for water and water canal extraction from L8 OLI imagery, and can be extended for other high resolution sensors.

Robust optical properties of Re0.5Sr0.5CoO3−δ (Re = Nd, Eu, Gd) ceramics for high temperature solar absorber applications

The efficiency of concentrated solar power (CSP) systems depends highly on the operating temperature. Currently, challenge remains on developing a solar absorber that not only possesses good optical performance but also excellent thermal stability at high temperature in air. Herein, the optical properties of Re0.5Sr0.5CoO3−δ (Re = Nd, Eu, Gd, ReSC-5) ceramics were investigated to evaluate their potential application as high temperature solar absorbers. Results showed that the reflectance spectra of ReSC-5 exhibited low reflectance values in the 0.3–2.5 μm wavelength range and high reflectance values in the wavelength range of 2.5–15 μm (infrared range). The spectral selectivity of ReSC-5 (2.3–2.9) is higher than that of SiC ceramic (1.0). Besides, the ReSC-5 ceramics showed low radiation temperature at high temperature and robust optical properties even underwent heat treatment at 800 °C for 9 h in air. These results suggest that the ReSC-5 ceramics are promising candidate for high temperature solar absorbers.

Rock Sample Surface Preparation Influences Thermal Infrared Spectra

High-resolution laboratory-based thermal infrared spectroscopy is an up-and-coming tool in the field of geological remote sensing. Its spatial resolution allows for detailed analyses at centimeter to sub-millimeter scales. However, this increase in resolution creates challenges with sample characteristics, such as grain size, surface roughness, and porosity, which can influence the spectral signature. This research explores the effect of rock sample surface preparation on the thermal infrared spectral signatures. We applied three surface preparation methods (split, saw, and polish) to determine how the resulting differences in surface roughness affects both the spectral shape as well as the spectral contrast. The selected samples are a pure quartz sandstone, a quartz sandstone containing a small percentage of kaolinite, and an intermediate-grained gabbro. To avoid instrument or measurement type biases we conducted measurements on three TIR instruments, resulting in directional hemispherical reflectance spectra, emissivity spectra and bi-directional reflectance images. Surface imaging and analyses were performed with scanning electron microscopy and profilometer measurements. We demonstrate that surface preparation affects the TIR spectral signatures influencing both the spectral contrast, as well as the spectral shape. The results show that polished surfaces predominantly display a high spectral contrast while the sawed and split surfaces display up to 25% lower reflectance values. Furthermore, the sawed and split surfaces display spectral signature shape differences at specific wavelengths, which we link to mineral transmission features, surface orientation effects, and multiple reflections in fine-grained minerals. Hence, the influence of rock surface preparation should be taken in consideration to avoid an inaccurate geological interpretation.

Convective Boundary Layer Depth Estimation from S-Band Dual-Polarization Radar

AbstractThis study investigates Bragg scatter signatures in dual-polarization radar observations, which are defined by low differential reflectivity values, as a proxy for convective boundary layer (CBL) depth. Using data from the WSR-88D in Twin Lakes, Oklahoma (KTLX), local minima in quasi-vertical profiles of are found to provide a reasonable estimate of CBL depth when compared with depth estimates from upper-air soundings from Norman, Oklahoma (KOUN), during 2014. The 243 Bragg scatter and upper-air sounding CBL depth estimates have a correlation of 0.90 and an RMSE of 254 m. Using Bragg scatter as a proxy for CBL depth was expanded to other seasons and locations—performing well in Wilmington, Ohio; Fairbanks, Alaska; Tucson, Arizona; Minneapolis, Minnesota; Albany, New York; Portland, Oregon; and Tampa, Florida—showing its potential usefulness in monitoring CBL depth throughout the year in a variety of geographic locations and meteorological conditions.

Determining the confined optical length of high index vertical Si nanoforest arrays for photonic applications

The structural and the optical properties of different Si nanostructures have been compared. Detailed optical properties of Si nanowires arrays of different optical lengths, fabricated by facile electroless etching technique, have been reported. The theoretical calculation of exponential sine profile at constant λ = 600 nm shows a better explanation in terms of gradient index with optical length for vertical nanowires. The observations signify the possibility of strong light trapping due to an exponential gradient towards the high index along the nanowires and the existence of dense subwavelength features. The optical admittance (Ƶ) shows a strong impact on optical distance (Z) for Z < H, owing to the electromagnetic wave interaction with the nanowires that perceive a different Ƶ at the oblique angle of incidence (AOI). In addition, the experimental reflectance data and the theoretical model for transverse electric and transverse magnetic modes predict that an optical length of 5 μm can exhibit a very low reflectance value. This indicates that the Si nanowires are polarization insensitive over a wide range of AOI (0°–80°). Moreover, Raman spectra showed a very strong light confinement effect in the first order transverse optical band with increasing etching depths. The morphological dependent resonance theory predicts a strong localized light field confinement in the lower wavelength regime for SiNWs. The effect on the strong resonant absorption modes was further correlated with the simulation results obtained by using COMSOL. The obtained results are likely to enhance the maximum absorption of SiNWs for various photonic applications.

Using an Object-Based Approach to Quantify the Spatial Structure of Reflectivity Regions in Hurricane Isabel (2003). Part I: Comparisons between Radar Observations and Model Simulations

Abstract When a hurricane undergoes extratropical transition (ET), its rainbands evolve from a circular and compact shape to a more elongated, fragmented, and dispersed configuration with an exposed circulation center. This study calculates five metrics to measure these spatial changes in reflectivity regions as Hurricane Isabel (2003) underwent ET. A mosaic of observations from the Weather Surveillance Radar-1988 Doppler (WSR-88D) network is compared to reflectivity simulated by the Advanced Research Weather Research and Forecasting (WRF-ARW) Model. Six simulations are performed by varying the cumulus and microphysics parameterizations to produce a range of reflectivity configurations. A bias correction is applied to model-simulated reflectivity prior to the calculation of spatial metrics because lower reflectivity values are generally underrepresented, while higher values are generally overrepresented. However, the simulation with Kain–Fritsch cumulus and Morrison two-moment microphysics overpredicts reflectivity by 3–4 dBZ at all levels. We demonstrate that the spatial metrics effectively capture structural changes as reflectivity regions became more fragmented and dispersed and the center became more exposed. In this case study, the results were more sensitive to the choice of cumulus physics, compared with the choice of microphysics. The Kain–Fritsch simulations produce shapes that are too circular and solid when compared with WSR-88D observations, as the hurricanes lack distinct outer rainbands. Simulations with Tiedtke cumulus produce an elongated main reflectivity region as in WSR-88D, but with separate inner and outer rainbands that are too dispersed and fragmented. These results demonstrate the value in measuring spatial patterns rather than assessing model performance using visual inspection alone.

Pyrobitumen in South China: Organic petrology, chemical composition and geological significance

Pyrobitumen has been discovered in the dolostone reservoir of the Central Sichuan Basin, southwest China, accumulates coevally with hydrothermal minerals in pores. The pyrobitumen has strong anisotropy with an evolutionary sequence from mosaic to a fibrous texture. A similar sequence of anisotropy has also been observed in mesophase pitch during the process of coking coal. Reflectance of the pyrobitumen shows a positive correlation with anisotropic evolution and increasing depth. Hopane and sterane biomarkers are abundant in extracts of highly anisotropic pyrobitumen with smooth, rough, hyperplastic surface and honeycomb micropores. Methylpyrene and methylchrysene maturity indicators and the reflectance values of pyrobitumen show a positive linear correlation in Cambrian samples, but show random correlation in Sinian samples. Fluid inclusion microthermometry of hydrothermal minerals, together with the burial and heat flow history of the reservoir indicate an abrupt thermal event that may have impacted the generation and evolution of pyrobitumen. This appears to be confirmed by the reflectance values of pyrobitumen in the source rock and reservoir. The pyrobitumen in source rock was less heated by the hydrothermal fluid due to its poor porosity and have lower reflectance values. However, the pyrobitumen in weathering crust reservoir was more heated by the hydrothermal fluid and have higher reflectance values, because the reservoir rocks have higher porosity. The occurrence and characteristics of pyrobitumen indicate an in-situ pyrolysis of oil, which was triggered by an abrupt thermal event in the reservoir. The reconstruction of burial history and heat flow, as well as the hydrothermal fluid minerals of the dolomite reservoir all indicate the thermal event of the Sichuan Basin might correlate with the Emei mantle plume in Late Permian.

Measurement of the Coefficient of Absorption and Reflection in Textile Materials with the Model Spctral2

The chemical staining treatment on a textile material, define the color of each one. The dark color with a very low reflectance value, tend to reflect less light and absorb more thermal energy, on the other hand the light color with high reflectance value absorb less thermal energy. In this paper, with the SPCTRAL2 model describes that the solar irradiance flux that reaches the terrestrial surface, we calculate the absorption and reflection coefficients of certain textile materials of different colors.

An Innovative Approach to Exploit the Reflection Spectroscopy of Liquid Characteristics.

Reflection spectroscopy, in the visible-near-infrared-shortwave infrared region (Vis-NIR-SWIR, 350-2500 nm), is a useful technology to extract chemical and physical properties of materials, but might be useless in identifying the spectral features of transparent or dark opaque liquids. Low reflectance values of a liquid reduce the ability to identify characteristic absorption features at specific wavelengths in the reflectance spectrum. In this study, we present a rapid and easy-to-use method to increase the measured reflectance spectrum and expose characteristic absorption features of a liquid. This was done by mixing the liquid with a white enhanced substance (WES). For this purpose, we used aluminum oxide (Al2O3) powder-a very bright (high albedo) substance and featureless across the entire Vis-NIR-SWIR region. The reflectance spectrum of the mixture-liquid and WES-was measured using a spectroradiometer. This procedure enabled to identify characteristic spectral features of the liquids that would have not been observed in the reflectance spectrum measured from the liquid alone.

High performance TiO2 nanotubes antireflection coating

The present study analyzes the use of TiO2 layer as antireflection coating. TiO2 thin films were prepared on silicon substrate by electrochemical anodization process with thicknesses of 130 and 170nm. The films exhibit a uniform nanotubular structure. The ellipsometry measurement data were analyzed using a multi-layer model, the bottom layer is a dense layer of TiO2 and the top layers are porous; they are formed by a mixture of TiO2 and void. The values of refractive index are obtained by the Bruggeman effective medium approximation. The refractive indexes of the bottom and top TiO2 sublayers were about 2.3 and 1.6, respectively. The lower values of reflectance are obtained with the thinnest film. For these samples the reflectance decreases about 90% compared to silicon and in some cases the reflectivity is less than 5%. The thickness influences of TiO2 thin films and their synthesis parameters on the optical constants are discussed.

Responsivity to solar irradiation and the behavior of carrier transports for MoS2/Si and MoS2/Si nanowires/Si devices

The behavior of carrier transports and the responsivity to solar irradiation are studied for MoS2/n-type Si (n-Si) and MoS2/Si nanowires (SiNWs)/n-Si device. The MoS2 thin films were prepared by the sol–gel method. The MoS2/n-Si and MoS2/SiNWs/n-Si devices exhibit reliable rectification behavior. The thermionic emission-diffusion model is the dominant process in these fabricated MoS2/n-Si and MoS2/SiNWs/n-Si devices. By applying the insertion of the SiNWs, the responsivity to solar irradiation can be effectively increased. Because of the low reflectance values for the MoS2/SiNWs/n-Si sample, the increased photocurrent density for the MoS2/SiNWs/n-Si device is due to high external light injection efficiency. MoS2/SiNWs/n-Si devices benefit from the high surface to volume ratio for SiNWs leading to a high responsivity of the device. The photo-response results confirm that the decay in the photocurrent is due to the dominance of short-lifetime electron trapping in the MoS2 thin film.

Fabrication of Cu2O nanocrystalline thin films photosensor prepared by RF sputtering technique

Cuprous oxide (Cu2O) nanocrystalline thin films were prepared on two types of substrates known as crystalline silicon and amorphous glass, by radio frequency reactive magnetron sputtering method. Scanning electron microscopy images confirmed that Cu2O particles covered the entire surface of both substrates with smoothing distribution. The root mean square surface roughness for the prepared Cu2O thin films on glass and Si (111) substrates is 4.16, and 3.36nm, respectively. Meanwhile, X-ray diffraction results demonstrated that the two phases of Cu2O and CuO were produced on Si (111) and glass substrates. The optical bandgap of Cu2O thin films synthesised on glass substrate is 2.42eV. Furthermore, the prepared Cu2O nanocrystalline thin films have showed low reflectance value in the visible spectrum. Metal-Semiconductor-Metal photodetector based Cu2O nanocrystalline thin films deposited onto Si (111) was fabricated using aluminium and platinum, with the current-voltage and photoresponse characteristic investigated under various applied bias voltages. The fabricated Metal-Semiconductor-Metal (M-S-M) photodetector had shown 126% sensitivity in the presence of 10mW/cm2 of 490nm light with 1.0V bias, displaying 90 and 100ms response and recovery times, respectively. These findings have demonstrated the suitability of M-S-M Cu2O photodetector as an affordable photosensor in the future.

Evaluation of the GPM-DPR snowfall detection capability: Comparison with CloudSat-CPR

An important objective of the Global Precipitation Measurement (GPM) mission is the detection of falling snow, since it accounts for a significant fraction of precipitation in the mid-high latitudes. The GPM Core Observatory carries the first spaceborne Dual-frequency Precipitation Radar (DPR), designed with enhanced sensitivity to detect lighter liquid and solid precipitation.The primary goal of this study is to assess the DPR's ability to identify snowfall using near-coincident CloudSat Cloud Profiling Radar (CPR) observations and products as an independent reference dataset. CloudSat near global coverage and high sensitivity of the W-band CPR make it very suitable for snowfall-related research. While DPR/CPR radar sensitivity disparities contribute substantially to snowfall detection differences, this study also analyzes other factors such as precipitation phase discriminators that produce snowfall identification discrepancies. Results show that even if the occurrence of snowfall events correctly detected by DPR products is quite small compared to CPR (around 5–7%), the fraction of snowfall mass is not negligible (29–34%). A direct comparison of CPR and DPR reflectivities illustrates that DPR misdetection is worsened by a noise-reducing DPR algorithm component that corrects the measured reflectivity. This procedure eliminates the receiver noise and side lobe clutter effects, but also removes radar signals related to snowfall events that are associated with relatively low reflectivity values. In an effort to increase DPR signal fidelity associated with snowfall, this paper proposes a simple algorithm using matched DPR Ku/Ka radar reflectivities producing an increase of the fraction of snowfall mass detected by DPR up to 59%.

Paleogene igneous intrusion and its effect on thermal maturity of organic-rich mudstones in the Beibuwan Basin, South China Sea

The seismic, drilling and logging data reveal that a large-scale igneous intrusion with a width of 14 Km and a maximum thickness of 170 m intruded within the Paleogene Liushagang Formation in the Fushan Depression, Beibuwan Basin, South China Sea (SCS). In this study, we report the geochemistry and Sr-Nd-Pb-Hf isotopic compositions of the igneous rocks, and evaluate the thermal effect induced by this large-scale igneous intrusion on the host rocks. The analyzed igneous samples exhibit strong enrichment in light rare earth elements (LREE) and large-ion lithophile elements (LILE), having characteristics similar to intra-plate oceanic island basalts (OIB). The Sr-Nd-Pb-Hf isotopic data display narrow ranges (e.g. 87Sr/86Sri = 0.7042–0.7044, 143Nd/144Ndi = 0.5128–0.5129, 206Pb/204Pbi = 18.90–18.94, εHf(t) = +7.56∼+9.60). Geochemical and isotopic compositions suggest a mixed mantle source between depleted mid-ocean-ridge-basalt (MORB) mantle (DMM)-like mantle and enriched mantle type II (EMII, possibly the Hainan mantle plume). Vitrinite reflectance values, major mineralogical changes together with a maturity-related biomarker [Ts/(Ts + Tm)] all reveal significant thermal effect induced by the igneous intrusion. Vitrinite reflectance values of the host rock are up to 2.5% in the intrusion region, whereas lower reflectance values (0.62–0.73%) occur in the unaffected area of the same strata. Moreover, our results suggest that the host rocks above the igneous intrusion are characterised by higher maturity than below, which should be attributed to the different behavior of hydrothermal fluids. These observations suggest that the thermal effect of large-scale thick igneous intrusions is much more intense than that of thin igneous intrusions, and the behavior of hydrothermal fluids induced by magmatic intrusive events should be a critical impact factor during heat transfer process.

Enhancement of Light Absorption in Photovoltaic Devices using Textured Polydimethylsiloxane Stickers.

We designed and fabricated a random-size inverted-pyramid-structured polydimethylsiloxane (RSIPS-PDMS) sticker to enhance the light absorption of solar cells and thus increase their efficiency. The fabricated sticker was laminated onto bare glass and crystalline silicon (c-Si) surfaces; consequently, low solar-weighted reflectance values were obtained for these surfaces (6.88 and 17.2%, respectively). In addition, we found that incident light was refracted at the PDMS-air interface of each RSIPS, which redirected the incident power and significantly increased the optical path length in the RSIPS-PDMS sticker which was 14.7% greater than that in a flat-PDMS sticker. Moreover, we investigated power reflection and propagation through the RSIPS-PDMS sticker using a finite-difference time-domain method. By attaching an RSIPS-PDMS sticker onto both an organic solar cell (OSC) based on a glass substrate and a c-Si solar cell, the power conversion efficiency of the OSC and the c-Si solar cell were increased from 8.57 to 8.94% and from 16.2 to 17.9%, respectively. Thus, the RSIPS-PDMS sticker is expected to be universally applicable to the surfaces of solar cells to enhance their light absorption.

Behavior of carrier transports and their sensitivity to solar irradiation for devices that use MoS2 that is directly deposited on Si using the chemical vapor method

To fabricate a MoS2/Si device, layers of MoS2 are directly deposited on an n-type Si substrate by chemical vapor deposition (CVD). No transfer processes are needed. The MoS2 thin film that is deposited on the n-type Si substrate exhibits p-type behavior and the MoS2/Si device exhibits stable rectification behavior. It is found that the thermionic emission–diffusion model is the dominant process in this fabricated MoS2/Si device. The MoS2/Si device also exhibits high sensitivity to solar irradiation. Because of the low reflectance values for the MoS2/Si samples, the enhanced sensitivity is due to high external light injection efficiency. This study provides valuable scientific information for multiple layered MoS2 films for other electronic and optoelectronic applications.