bluuebunny/crossref_metadata_2025 huggingface dataset:
Contrasting Groundwater and Streamflow Ages at the Maimai Watershed
Authors: Gabrielli C. P. , Morgenstern U. , Stewart M. K. , McDonnell J. J.
Published: May 2018

Understanding the links between groundwater age, runoff generation processes, and their effects on stream water transit time (TT) is a major research challenge. Here we present new tritium age dating and hydrogeological characterization from 40 bedrock wells drilled at the intensively studied Maimai Experimental Watershed in New Zealand. We investigated the extent, dynamics, and age of the groundwater in a 4.5 ha headwater catchment over a 400 day period. In particular, we explored the controls of bedrock structure on aquifer dynamics, the aquifer flow domain and its influence on time‐varying stream water TT. We show that low permeability hillslope bedrock minimizes deep recharge, thereby regulating groundwater age, stream water MTT, and surface water‐groundwater interaction. Two distinct hydrologic units can represent catchment storage: shallow young soil storage and deep much older bedrock groundwater. Groundwater ages near discharge zones were up to 23 years compared to soil water ages that ranged between 0.1 and 0.5 years. This difference in age for the two main storages resulted in contrasting seasonal stream water TT response. During the 8 month wet season, stream water TT was young and stable while stream water TT in the slightly drier summer season was highly dynamic. These qualitative field observations are a process exemplar that support the Berghuijs and Kirchner (2017) quantitative descriptions of preferential release of young streamflow; and for the Maimai catchment, support the notion that most groundwater is exchanged only slowly with the surface and is therefore relatively old.
What Makes a First‐Magnitude Spring?: Global Sensitivity Analysis of a Speleogenesis Model to Gain Insight into Karst Network and Spring Genesis
Authors: Henson Wesley R. , de Rooij Rob , Graham Wendy
Published: May 2018

Often, karstic conduit network geometry is unknown. This lack of knowledge represents a significant limitation when modeling flow and solute transport in karst systems. In this study, we apply Morris Method Global Sensitivity Analysis to a speleogenesis model to identify model input parameters, and combinations thereof, that most significantly influence evolution of karst conduit networks, development of first‐magnitude springs, and resulting flow and solute transport pulse responses. Based on an idealized model of the Silver Springshed in Central Florida USA, results showed that porous matrix hydraulic conductivity and parameters that govern connectivity of vertical and horizontal preferential flow paths (proto‐conduits) are the most influential parameters. In particular, a lower porous matrix conductivity is more likely to produce a first‐order magnitude spring. For the boundary conditions assumed in this application, conduits tend to develop in low topographic regions that drained nearby high regions. Morris ensemble realizations that generated first‐magnitude springs exhibit similar flow and solute transport pulse responses at the spring vent, despite differences in network configuration. However, distributed head fields are highly spatially variable, implying substantial spatial variability among solute flow paths and travel times from the land surface to the spring across realizations.
A Method for Objectively Integrating Soil Moisture Satellite Observations and Model Simulations Toward a Blended Drought Index
Authors: Yin Jifu , Zhan Xiwu , Hain Christopher R. , Liu Jicheng , Anderson Martha C.
Published: May 2018

With satellite soil moisture (SM) retrievals becoming widely and continuously available, we aim to develop a method to objectively integrate the drought indices into one that is more accurate and consistently reliable. The data sets used in this paper include the Noah land surface model‐based SM estimations, Atmosphere‐Land‐Exchange‐Inverse model‐based Evaporative Stress Index, and the satellite SM products from the Advanced Scatterometer, WindSat, Soil Moisture and Ocean Salinity, and Soil Moisture Operational Product System. Using the Triple Collocation Error Model (TCEM) to quantify the uncertainties of these data, we developed an optically blended drought index (BDI_b) that objectively integrates drought estimations with the lowest TCEM‐derived root‐mean‐square‐errors in this paper. With respect to the reported drought records and the drought monitoring benchmarks including the U.S. Drought Monitor, the Palmer Drought Severity Index and the standardized precipitation evapotranspiration index products, the BDI_b was compared with the sample average blending drought index (BDI_s) and the RMSE‐weighted average blending drought indices (BDI_w). Relative to the BDI_s and the BDI_w, the BDI_b performs more consistently with the drought monitoring benchmarks. With respect to the official drought records, the developed BDI_b shows the best performance on tracking drought development in terms of time evolution and spatial patterns of 2010‐Russia, 2011‐USA, 2013‐New Zealand droughts and other reported agricultural drought occurrences over the 2009–2014 period. These results suggest that model simulations and remotely sensed observations of SM can be objectively translated into useful information for drought monitoring and early warning, in turn can reduce drought risk and impacts.
Balancing the Global Distribution of Phosphorus With a View Toward Sustainability and Equity
Authors: Filippelli Gabriel M.
Published: May 2018

Limitations in the geological reserves of phosphate rock, the source of fertilizer phosphorus, are not currently considered in agricultural practices or global trade, a very short‐sighted approach considering that there is no “alternative fuel” for plant growth. Thus, it is important to understand the science of phosphorus‐crop growth dynamics as a function of grain type, plant uptake, climate, and past fertilizer phosphorus application history. Recent work on modeling these factors on the global scale (Kvakić et al., 2018, https://doi.org/10.1002/2017GB005754) provides the first scientific backdrop for developing an understanding of fertilizer phosphorus balances and for informing forward‐looking practices and policies that regulate toward long‐term sustainability rather than short‐term profit.
REY‐Th‐U Dynamics in the Critical Zone: Combined Influence of Reactive Bedrock Accessory Minerals, Authigenic Phases, and Hydrological Sorting (Mule Hole Watershed, South India)
Authors: Braun Jean‐Jacques , Riotte Jean , Battacharya Shrema , Violette Aurélie , Oliva Priscia , Prunier Jonathan , Maréchal Jean‐Christophe , Ruiz Laurent , Audry Stéphane , Subramanian S.
Published: May 2018

The sources of REY‐Th‐U and long‐term mass balance were assessed in the gneissic tropical forested Critical Zone Observatory of Mule Hole, India. The study relies on the characterization of the solid compartments (bedrock, soils, streambed and suspended sediments), on batch leaching experiments of the parent gneiss and on extractions of cation‐exchangeable and iron‐related pools of selected soil samples. The REY‐Th‐U primary reservoir is controlled by monazite, xenotime, thorite, allanite, bastnesite, titanite, apatite, and, to a lesser extent, by zircon. This accessory mineral assemblage was profoundly modified by episodes of metamorphism and hydrothermal activity. Allanite, bastnesite, titanite, and apatite are prone to break down at incipient weathering stage while monazite, xenotime and zircon are resistant minerals. On a long‐term basis, REY are roughly inert in the immature saprolite and depleted in the soil cover and are strongly redistributed among secondary phases. LREE and HREY are mainly controlled by poorly crystallized secondary iron oxides and oxyhydroxides, and, to a lesser extent, by secondary phosphates (e.g., rhabdophane). Th, inert in the saprolite, is controlled by well‐crystallized secondary iron oxides and oxyhydroxides and likely by secondary thorianite (ThO2). REY and Th are not easily mobilized during surface processes such as chelation by organic matter and uptake by plants. REY and Th are, by far, exported as suspended sediments associated with iron oxides. The U export by groundwater and suspended sediments dominates over those of streambed sediments and stream.
The Morphology of the 6‐Day Wave in Both the Neutral Atmosphere and F Region Ionosphere Under Solar Minimum Conditions
Authors: Gu Sheng‐Yang , Ruan Haibing , Yang Cheng‐Yun , Gan Quan , Dou Xiankang , Wang Ningning
Published: May 2018

Combined Thermosphere‐Ionosphere‐Mesosphere Energetics and Dynamics (TIMED)/TIMED Doppler interferometer horizontal winds, Global Positioning System Total Electron Content maps, and Constellation Observing System for Meteorology, Ionosphere, and Climate electron density profiles are utilized to study the westward zonal wavenumber 1 quasi‐6‐day planetary wave in both the neutral atmosphere and F region ionosphere under solar minimum conditions in 2009. It is found that the zonal (meridional) wind perturbations maximize (minimize) in the geographic equatorial mesosphere and lower thermosphere region and are in phase (out of phase) between hemispheres, which agrees well with both the Upper Atmosphere Research Satellite/high‐resolution Doppler imager wind observations and (1, 1) Rossby normal mode. Analysis of the Total Electron Content maps and Constellation Observing System for Meteorology, Ionosphere, and Climate electron density profiles shows that the F region ionosphere exhibits wave spectra and temporal variations that are consistent with those of the neutral atmosphere. Specifically, the 6‐day oscillation in electron density is the highest during 1200–1800 LT in the equatorial ionospheric anomaly region (~20° geomagnetic latitude), with a minimum amplitude at the equator, which agrees well with the F region fountain effect. At 300 km, the amplitude of the electron density oscillation reaches ~1.2 × 104 cm−3, which accounts for ~14% of the background value. In addition, the F2 layer electron peak density and peak height also exhibit corresponding oscillations with amplitudes of ~9 × 104 cm−3 and ~12 km, respectively. The current work provides clear evidence for F region ionospheric responses to planetary waves in the mesosphere and lower thermosphere region.
Reconciling the Attribution of Changes in Streamflow Extremes From a Hydroclimate Perspective
Authors: Yuan Xing , Jiao Yang , Yang Dawen , Lei Huimin
Published: May 2018

With increasing impacts of climate change and human interventions on the hydrological cycle, attributions of changes in streamflow and its extremes were widely carried out to provide guidelines for adaptation. However, most of them neglected either human‐induced climate or hydrological change. Here we propose a reconciled framework to attribute influences from anthropogenic and natural climate change, land cover change and human water withdrawal. A set of 45 years high‐resolution (0.01°) land surface hydrological simulations were conducted over a semiarid river basin in North China, forced by changing climate and/or land cover scenarios. There are discernible anthropogenic climate change fingerprints on the changes in annual mean streamflow and wet extremes (ratio of wet months), while land cover change and water withdrawal are more important for the change in dry extremes (ratio of dry months). The impact of human‐induced hydroclimate change on streamflow extremes could be underestimated by up to 21–59% or 12–43% based on hydrological or climate attribution alone, suggesting the necessity of the reconciled framework for distinguishing different anthropogenic factors.
Immortalized common marmoset (Callithrix jacchus) hepatic progenitor cells possess bipotentiality in vitro and in vivo
Authors: Guo Zhenglong , Jing Renwei , Rao Quan , Zhang Ludi , Gao Yimeng , Liu Fengyong , Wang Xin , Hui Lijian , Yin HaiFang
Published: May 2018

Common marmoset (Callithrix jacchus) is emerging as a clinically relevant nonhuman primate model for various diseases, but is hindered by the availability of marmoset cell lines, which are critical for understanding the disease pathogenesis and drug/toxicological screening prior to animal testing. Here we describe the generation of immortalized marmoset hepatic progenitor cells (MHPCs) by lentivirus-mediated transfer of the simian virus 40 large T antigen gene in fetal liver polygonal cells. MHPCs proliferate indefinitely in vitro without chromosomal alteration and telomere shortening. These cells possess hepatic progenitor cell-specific gene expression profiles with potential to differentiate into both hepatocytic and cholangiocytic lineages in vitro and in vivo and also can be genetically modified. Importantly, injected MHPCs repopulated the injured liver of fumarylacetoacetate hydrolase (Fah)-deficient mice with hepatocyte-like cells. MHPCs also engraft as cholangiocytes into bile ducts of 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC)-induced bile ductular injured mice. MHPCs provide a tool to enable efficient derivation and genetic modification of both hepatocytes and cholangiocytes for use in disease modeling, tissue engineering, and drug screening.
Wave-packet multi-scale simulations based on a non-linear tight-binding Hamiltonian for carrier transport in π-conjugated polymers
Authors: Tada Tomofumi
Published: May 2018

Multi-scale calculation based on DFT and Hückel for carrier mobility on 1 micro-meter wires reveals that localization can enhance the mobility.
A voltammetric method for Fe(iii) in blood serum using a screen-printed electrode modified with a Schiff base ionophore
Authors: Mittal Susheel K. , Rana Sonia , Kaur Navneet , Banks Craig E.
Published: May 2018

A miniaturized disposable screen-printed electrode for the detection of Fe(iii) at the micro-molar level.
Analysis of 14C-bearing compounds released by the corrosion of irradiated steel using accelerator mass spectrometry
Authors: Cvetković B. Z. , Salazar G. , Kunz D. , Szidat S. , Wieland E.
Published: May 2018

The combination of ion chromatography (IC) with accelerator mass spectrometry (AMS) was developed to determine the speciation of 14C-(radiocarbon) bearing organic compounds in the femto to pico molar concentration range.
An enzymatic polymerization-activated silver nanocluster probe forin situapoptosis assay
Authors: Zhu Rong , Luo Xingyu , Deng Lu , Lei Chunyang , Huang Yan , Nie Zhou , Yao Shouzhuo
Published: May 2018

A DNA/AgNC probe was developed forin situapoptosis assay based on an enzyme-polymerized poly-dA DNA chain and strand displacement.
Piperidinium ionic liquids as electrolyte solvents for sustained high temperature supercapacitor operation
Authors: Chapman Varela Jennifer , Sankar Karthika , Hino Alexander , Lin Xinrong , Chang Won-seok , Coker David , Grinstaff Mark
Published: May 2018

A supercapacitor with a piperidinium ionic liquid and an LiTFSI electrolyte operates for 10 000+ cycles at 100 °C.
Study of oxygen evolution reaction on amorphous Au13@Ni120P50 nanocluster
Authors: Wang Yanzhou , Gao Panpan , Wang Xiaoxu , Huo Jinrong , Li Lu , Zhang Yajing , Volinsky Alex A. , Qian Ping , Su Yanjing
Published: May 2018

Potential energy changes of the four consecutive elementary reaction steps for OER on the surfaces of both bumpy Au13@Ni120P50 nanocluster and clean Ni12P5(001) supported by bulk Au, respectively.
Dynamics in a one-dimensional ferrogel model: relaxation, pairing, shock-wave propagation
Authors: Goh Segun , Menzel Andreas M. , Löwen Hartmut
Published: May 2018

Based on theory and simulations, we elucidate the relaxation dynamics of a one-dimensional ferrogel model and provide classification scenarios.
Anticancer potential against cervix cancer (HeLa) cell line of probiotic Lactobacillus casei and Lactobacillus paracasei strains isolated from human breast milk
Authors: Riaz Rajoka Muhammad Shahid , Zhao Haobin , Lu Yao , Lian Ziyang , Li Na , Hussain Nazim , Shao Dongyan , Jin Mingliang , Li Qi , Shi Junling
Published: May 2018

The CFCS of Lactobacilli strains from human breast milk induced apoptosis in HeLa cells ROS related mitochondrial pathway.
Accurate experimental determination of gallium K- and L3-shell XRF fundamental parameters
Authors: Unterumsberger Rainer , Hönicke Philipp , Colaux Julien L. , Jeynes Chris , Wansleben Malte , Müller Matthias , Beckhoff Burkhard
Published: May 2018

The fluorescence yield of the K- and L3-shell of gallium was determined using the radiometrically calibrated (reference-free) X-ray fluorescence instrumentation at the BESSY II synchrotron radiation facility.
A tailor-made design of lipidic bicontinuous cubic matrices using amino acid ionic liquids as self-assembly media
Authors: Fujiwara Saki , Ohno Hiroyuki , Ichikawa Takahiro
Published: May 2018

Bicontinuous cubic liquid-crystalline matrices with unique characteristics have been prepared by mixing monoolein and amino acid ionic liquids.
Dispersive liquid–liquid microextraction using magnetic room temperature ionic liquid for extraction of ultra-trace amounts of parabens
Authors: Zavar Mousavi Kobra , Yamini Yadollah , Seidi Shahram
Published: May 2018

In this work, a dispersive liquid–liquid microextraction method using methyltrioctylammonium tetrachloroferrate was employed for the extraction of ultratrace amounts of parabens in water, beer and beverage samples.
First-principles study on ferromagnetism in 4H-SiC codoped with Al and Mn
Authors: Lin Long , Zhu Linghao , Zhao Ruiqi , Tao Hualong , Huang Jingtao , Xu Yonghao , Zhang Zhanying
Published: May 2018

The electronic structures and magnetic properties in 4H-SiC codoped with Al and Mn have been investigated systematically based on density functional theory.
Synthesis of hydrated KTaWO6 nanoparticles and Sn(ii) incorporation for visible light absorption
Authors: Weiss Morten , Marschall Roland
Published: May 2018

The defect-pyrochlore stuctured semiconductor KTaWO6 has been prepared via hydrothermal synthesis, resulting in single-crystalline nanoparticles with adjustable crystallite sizes between 15 and 24 nm.
Carbon coated core–shell multifunctional fluorescent SPIONs
Authors: Tiwari Ashish , Verma Navneet C. , Singh Anup , Nandi Chayan K. , Randhawa Jaspreet K.
Published: May 2018

A novel one step method to synthesize non-toxic carbon coated highly photostable core–shell magnetic and fluorescent SPIONs with long-lasting fluorescence alongside a superior magnetic resonance (MR) imaging ability.
A facet-controlled Rh3Pb2S2nanocage as an efficient and robust electrocatalyst toward the hydrogen evolution reaction
Authors: Kim Taekyung , Park Jongsik , Jin Haneul , Oh Aram , Baik Hionsuck , Joo Sang Hoon , Lee Kwangyeol
Published: May 2018

A new type of binary metal sulphide, Rh3Pb2S2, exhibits excellent electrocatalytic activity and durability toward the hydrogen evolution reaction under acidic conditions.
PbTe quantum dots as electron transfer intermediates for the enhanced hydrogen evolution reaction of amorphous MoSx/TiO2 nanotube arrays
Authors: Gao Shiyuan , Wang Bin , Liu Xinyu , Guo Zhanhu , Liu Zhongqing , Wang Yichao
Published: May 2018

PbTe quantum dots (QDs) function as electron transfer intermediates for higher electrocatalytic performances from MoSx/PbTe QDs/TNAs.
Ruthenium-catalyzed C–H allylation of arenes with allylic amines
Authors: Yan Rui , Wang Zhong-Xia
Published: May 2018

The Ru-catalyzed pyridyl-directed C–H allylation of arenes with allylic amines was carried out in the presence of 5 mol% of [Ru(p-cymene)Cl2]2 and 0.5 equiv. of AgOAc in CF3CH2OH.
Analysing processes of conceptualization for students in lessons on substance from the emergence of conceptual profile zones
Authors: Amaral Edenia Maria Ribeiro do , Ratis Tenório da Silva João Roberto , Sabino Jaqueline Dantas
Published: May 2018

In this paper, we analyze the process of conceptualization experienced by students in Secondary School when involved in activities in a teaching and learning sequence on the concept of substance, considering the emergence of zones of the conceptual profile. The results point out that the approaches to different modes of thinking of substance enabled the teacher to discuss and confront ideas, leading students to construct or share meanings stabilized in a scientific view. The conceptual profile was an important tool to design activities by creating discursive contexts involving different modes of thinking about substance, which contributed to raising specific discussions involving historical, scientific and social contexts to understand senses and meanings for substances.
Metal-free borylative dearomatization of indoles: exploring the divergent reactivity of aminoborane C–H borylation catalysts
Authors: Jayaraman Arumugam , Misal Castro Luis C. , Desrosiers Vincent , Fontaine Frédéric-Georges
Published: May 2018

We report the first example of catalytic dearomatization of indoles to generate 3-borylindolines using metal-free borane catalysts.
Topography-induced symmetry transition of droplets on quasi-periodically patterned surfaces
Authors: Chen Enhui , Yuan Quanzi , Zhao Ya-Pu
Published: May 2018

Quasi-periodic structures of quasicrystals yield novel effects in diverse systems. However, there is little investigation on employing quasi-periodic structures in morphology control.
Ultrahigh-performance tungsten-doped perovskites for the oxygen evolution reaction
Authors: Chen Gao , Hu Zhiwei , Zhu Yanping , Chen Zhi-Gang , Zhong Yijun , Lin Hong-Ji , Chen Chien-Te , Tjeng Liu Hao , Zhou Wei , Shao Zongping
Published: May 2018

Based on the materials genome strategy, a novel B-site cation ordered double perovskite SrCo0.4Fe0.2W0.4O3−δ has been designed as a highly efficient OER catalyst.
Domaines d’utilisation des contre plaques
Authors: TRIKI Hiba , BEKRI Sana , SADOURI Imen , TAKTAK Najla , MANSOUR Lamia
Published: May 2018

Quel que soit l’édentement, la prothèse partielle
amovible doit répondre aux principes de rigidité,
d’équilibre et de confort grâce à une conception
bien réfléchie des éléments constituants
le châssis.

Cependant, dans certaines situations cliniques,
cette conception se trouve modifiée pour mieux
gérer les impératifs esthétiques et fonctionnels
des patients.

Cet article présente les différentes formes
des contre plaques, leurs intérêts, impératifs
de conceptions et leurs inconvénients.
Comment garantir la stabilité prothétique en prothèse amovible complète (PAC) conventionnelle ?
Authors: GUESSOUS Doss Fadwa , REGRAGUI Anissa , MERZOUK Nadia , BENFDIL Faiza
Published: May 2018

En prothèse amovible complète, la stabilité
prothétique est la clé du succès de toute
réhabilitation prothétique quel que soit la situation
clinique. Grâce au confort qu’elle apporte
aux patients, elle améliore nettement leur qualité
de vie en leurs garantissant le rétablissement
des différentes fonctions orales fortement altérées
par la perte des dents ainsi qu’une intégration
organique et psychique de la prothèse. Ce pilier
de l’équilibre biomécanique de la prothèse
amovible complète est assuré d’une part par
une exploitation raisonnée des surfaces d’appui
verticales ou obliques constituant la surface
d’appui prothétique afin de s’opposer aux forces
horizontales développées pendant la mastication
par la musculature périphérique, et d’autre part par
l’établissement d’un équilibre occlusal parfait aussi
bien statique que dynamique sous forme d’une
occlusion intégralement équilibrée. La pérennité
du résultat obtenu dépend essentiellement
de la maintenance post-prothétique périodique.
Apport d’une étude transcriptomique et comportementale aux connaissances de l’impact des obstacles aquatiques sur les anguillettes migrantes
Authors: Podgorniak T. , De Oliveira E. , Daverat F. , Pierron F.
Published: May 2018

L’anguille européenneAnguilla anguillaest une espèce catadrome avec un cycle de vie complexe incluant des migrations entre la mer de Sargasses, l’Europe et l’Afrique du Nord. Du fait de sa baisse drastique de population depuis 30 ans, l’anguille est considérée aujourd’hui comme « en danger critique d’extinction ». Une des causes de ce déclin est la fragmentation de l’habitat. L’hypothèse de pression de sélection des obstacles aquatiques exercée sur les jeunes anguilles en migration a été étudiée avec une approche sansa priori, où un grand nombre de gènes a été analysé dans trois tissus (cerveau, foie, muscle) de chaque poisson provenant des zones amont/aval de l’obstacle. Les différences de transcription des gènes au niveau du cerveau des poissons ont été détectées. Ces différences sont liées à la plasticité neuronale et se maintiennent sur le long terme. De plus, il a été montré que les anguilles provenant des zones amont possèdent la tendance à l’escalade la plus forte et que certains poissons classés comme « leaders » d’escalade présentaient des niveaux de transcription de gènes liés à la cognition plus faibles que les « suiveurs ». Ces résultats peuvent être associés au concept de coping styleet de la personnalité animale. En effet, les « leaders » agiraient comme des individus proactifs et téméraires, contrairement aux suiveurs, plutôt réactifs et timides. L’implication de notre étude est discutée dans le contexte écologique, car la présence des obstacles peut modifier les patterns de distribution de phénotypes dans les réseaux aquatiques.
Improving geotechnical properties of clayey soil using polymer material
Authors: Karim Hussein , Al-Soudany Kawther
Published: May 2018

This study illustrates the application of polymer material for clayey soil stabilization. The article will focus on studying the strength behavior of the clayey soils reinforced with homogenously polymer fiber. In the current research, “polypropylene” was selected as polymer material to reinforce the natural clay soil. This polymer fiber was added to the clayey soil with four different percentages of (0, 1.5, 3, and 5%) by weight of soil. Various tests with different polymer contents were performed to study the effect of using such a polymer as a stabilizing agent on geotechnical properties of clay. As the fiber content increases, the optimum moisture content (OMC) is increased while the specific gravity decreases. For Atterberg’s limits, the results indicated increasing liquid limit and plasticity index while decreasing plastic limit with increase in polymer content. The outcomes of the tests also reflected a considerable improvement in the unconfined compressive strength with noticeable improvement in the shear strength parameter (undrained shear strength, cu) of the treated soils. The undrained shear strength obtained from treated soil with 5% polymer addition is more than three times that of the untreated soil. With an increase in polymer content, the consolidation parameters (Compression index Cc and recompression index Cr) decreases. Finally, the benefit of the reinforcement is increased with increasing polymer fiber content.
Improvement of clayey soil characteristics by using activated carbon
Authors: Al-Soudany Kawther , Al-Gharbawi Ahmed , Al-Noori Marwa
Published: May 2018

The clay soil is weak and unable to carry the applied loads as a result of the weight of buildings or vehicles on the load performing on the soil. In this research, clay soil was grained and mixed with different percentages of activated carbon additives to investigate its performance. One type of clay soil from Al-Taji city was used. The percentages of activated carbon 3, 5, 7 and 9% were added to the soil and the influence of the admixture was observed by comparing the results with the untreated soil. The selected properties for this comparison were specific gravity, consistency limits, compaction, static compaction, CBR, consolidation, swelling and unconfined compressive strength. The results showed that the plasticity index, maximum dry weight and specific gravity decreased as the percentage of additives increased. The unconfined compressive strength increased as the percentage of additives and curing periods (1, 7, 14 and 28)days increased. The amount of increase in soil strength was even more than 100% for the 9% activatedcarbon. The results showed that the addition of activated carbon has a positive effect to the geotechnical properties.
Effect of stabilizers on the shear strength of residual soil
Authors: Snodi Lamyaa Najah , Atemimi Yahya , Ahmad Fauziah binti
Published: May 2018

In this paper, chemical stabilizer was used for soil characteristics improvement. Styrene Butadiene Rubber (SBR) polymer and lime is effectively used as an inexpensive and easily applied material for soil stabilization and its response performance was evaluated. This research studied improving the engineering properties of Residual soil by mixing it with varying percentages of chemical stabilizer. An evaluation of the effectiveness and performance of SBR and Lime as a soil stabilizer was performed over a series of laboratory tests for geotechnical soil properties. Residual soil used in this study was lateritic soil. The soil was mixed with various amounts of stabilizer for polymer (SBR) {2.5, 5, 10 and 12.5 %} and for lime {1.25,2.5,5 and 10%} by weight and then compacted at the optimum moisture content (OMC) and maximum dry unit weight (MMD). The original soil and the stabilized samples were subjected to unconfined compression test to determine their strength at different curing times (7,14 and 28 day). The results showed a reduction in the plasticity index. The results showed an increase in strength.
Geotechnical properties of reinforced clayey soil using nylons carry’s bags by products
Authors: Salim Nahla , Al-Soudany Kawther , Jajjawi Nora
Published: May 2018

All structures built on soft soil may experience uncontrollable settlement and critical bearing capacity. This may not meet the design requirements for the geotechnical engineer. Soil stabilization is the change of these undesirable properties in order to meet the requirements. Traditional methods of stabilizing or through in-situ ground improvement such as compaction or replacement technique is usually costly. Now a safe and economic disposal of industrial wastes and development of economically feasible ground improvement techniques are the important challenges being faced by the engineering community. This work focuses on improving the soft soil brought from Baghdad by utilizing the local waste material for stabilization of soil, such as by using “Nylon carry bag’s by product” with the different percentage and corresponding to 1 %, 3% and 5% (the portion of stabilizer matters to soil net weight) of dried soil. The results indicated that as Nylon’s fiber content increases, the liquid limit decreases while the plastic limit increases, so the plasticity index decreases. Furthermore, the maximum dry density decreases while, the optimum moisture content increases as the Nylon’s fiber percentage increases. The compression index (decreases as the Nylon’s fiber increases and provides a maximum of 43% reduction by adding 5% nylon waste material. In addition, the results indicated that, the undrained shear strength increases as the nylon fiber increases.
Assessment of Al-Amarah street within the Al-kut city using pavement condition index (PCI) and GIS technique
Authors: Al-Neami Mohammed , Al-Rubaee Rasha , Kareem Zainab
Published: May 2018

The capabilities of geographical system and their spatial analysis is considered the most appropriate tools to enhance pavement management operations, with features such as graphical display of pavement condition. In Iraq, most of transportation agencies do not have a tool that is used as a database for road deteriorations, so there is a need for road surveying and storing the collected information in GIS to know the condition of every road with details. Furthermore, these data can be used for maintenance process and estimation of prior cost. This research has been carried out to estimate of flexible pavement condition through visual surveys using the Pavement Condition Index (PCI) method; so it can provide an easy way to calculate the PCI based on GIS data with Micro PAVER software 5.2. Al-Amarah Street, which is internal road in Al-Kut city in the eastern part of Iraq, is used as a case study. The average pavement condition index of the selected case study is found to be “64” using Micro PAVER 5.2 software which mean “Fair” pavement condition. Arc Map 9.3 has been applied in this study to make an integrated maintenance system for each road in the region demonstrating the annual road deteriorations and the resulting change in the PCI values which occurs every year. The study provides an easy and simplified way of presentation the details of deteriorations on the satellite or the geographical map of the road in which each type of distress has been symbolized with specific sign and each PCI value has been represented with specific color.
Effects of waste PVC addition on the properties of (40-50) grade asphalt
Authors: Salman Nawal , Jaleel Zeena
Published: May 2018

Disposal of plastic waste poses a serious threat nowadays. Effective solutions are required to reduce or eliminate this problem. One of these solutions is to use these materials in asphalt mixtures. PVC (Poly Vinyl Chloride) during melting has adhesive properties which can be used with asphalt to reduce the bitumen mixture costs. Investigation of physical characteristics of asphalt cement (40-50) mixed with PVC is presented in this paper. The main objective is to study the change in bitumen properties after mixing with PVC of percent (2.5, 5, 7.5, 10, 12 and 15) % by weight of bitumen. Penetration, ductility, loss on heating, softening point, flash and fire tests were conducted for each percent. It is concluded that penetration decreases by 62.8% on addition of 15% PVC. Ductility also drops when PVC dosage increases. Softening point increases when PVC dosage increases by 6 % for 15% PVC.
Behavior of high performance artificial lightweight aggregate concrete reinforced with hybrid fibers
Authors: Khalil Wasan , Ahmed Hisham , Hussein Zainab
Published: May 2018

In this investigation, sustainable High Performance Lightweight Aggregate Concrete (HPLWAC) containing artificial aggregate as coarse lightweight aggregate (LWA) and reinforced with mono fiber, double and triple hybrid fibers in different types and aspect ratios were produced. High performance artificial lightweight aggregate concrete mix with compressive strength of 47 MPa, oven dry density of 1828 kg/m3 at 28 days was prepared. The Fibers used included, macro hooked steel fiber with aspect ratio of 60 (type S1), macro crimped plastic fiber (P) with aspect ratio of 63, micro steel fiber with aspect ratio of 65 (type S), and micro polypropylene fiber (PP) with aspect ratio of 667. Four HPLWAC mixes were prepared including, one plain concrete mix (without fiber), one mono fiber reinforced concrete mixes (reinforced with plastic fiber with 0.75% volume fraction), one double hybrid fiber reinforced concrete mixes (0.5% plastic fiber + 0.25% steel fiber type S), and a mix with triple hybrid fiber (0.25% steel fiber type S1+ 0.25% polypropylene fiber + 0.25% steel fiber type S). Fresh (workability and fresh density) and hardened concrete properties (oven dry density, compressive strength, ultrasonic pulse velocity, splitting tensile strength, flexural strength, static modules of elasticity, thermal conductively, and water absorption) were studied. Generally, mono and hybrid (double and triple) fiber reinforced HPLWAC specimens give a significant increase in splitting tensile strength and flexural strength compared with plain HPLWAC specimens. The percentage increases in splitting tensile strength for specimens with mono plastic fiber are, 20.8%, 31.9%, 36.4% and 41%, while the percentage increases in flexure strength are 19.5%, 37%, 33.9% and 34.2% at 7, 28, 60, 90 days age respectively relative to the plain concrete. The maximum splitting tensile and flexure strengths were recorded for triple hybrid fiber reinforced HPLWAC specimens. The percentage increases in splitting tensile strength for triple hybrid fiber reinforced specimens are 19.5%, 37%, 33.9% and 34.2%, while the percentage increases in flexure strength are 50.5%, 62.4. %, 66.8% and 62.2% at 7, 28, 60 and 90 days age respectively relative to the plain concrete specimens.
Utilization of brick waste as pozzolanic material in concrete mix
Authors: Resin Raghda , Alwared Abeer , Al-Hubboubi Suhair
Published: May 2018

Recycling of construction and demolition waste and recycling of industrial by-products into building materials has an enormous potential. Brick waste can be treated by reusing for construction. Recently, the utilization of pozzolanic materials in cement and concrete have increased considerably due to their diverse benefits such as lesser use of cement , saving in production costs, improvement in the durability of concrete and so on. Ground bricks was added to concrete mix as partial replacement of cement at (5, 10, 15) % by weight. It was evaluated as a pozzolanic material in conjunction with high range water reducing admixture superplasticizer (HRWR)-The study confirmed that the use of 10 % of ground brick improved compressive, flexure strength of concrete by about (23.3%) and (5.92%) respectively at 240 days as compared to reference concrete and decreased the depth of water penetration under pressure by about 43.75% at 150 days, also the water absorption decreased by about 2.52%. The uses of 10% of grinding brick in conjunction with high range water reducing admixture reduced corrosion of steel reinforcement by about 18%.
Effect of internal curing on performance of self-compacting concrete by using sustainable materials
Authors: Aljalawi Nada , AL-Awadi Amar Yahia
Published: May 2018

This paper is devoted to investigate the effect of internal curing technique on the properties of self-compacting concrete. In this study, self-compacting concrete is produced by using limestone powder as partial replacement by weight of cement with percentage of (5%), sand is partially replaced by volume with saturated fine lightweight aggregate which is thermostone aggregate as internal curing material in three percentages of (5%, 10%, 15%) for self-compacting concrete, and the use of two external curing conditions which are water and air. The experimental work was divided into three parts: in the first part, the workability tests of fresh self-compacting concrete were conducted. The second part included conducting compressive strength test and modulus of rupture test at ages of (7, 28 and 90) days. The third part included doing the shrinkage test at age of (7, 14, 21, 28) days. The results show that internally cured self-compacting concrete has the best workability and the best properties of hardened concrete which include (compressive strength, modulus of rupture) of externally cured self-compacting concrete with both water and air as compared with reference concretes. Also, the hardened properties of internally cured self-compacting concrete with percentage of (5%) with thermostone aggregate is the best as compared with that of percentages (10% and 15%) in both external curing conditions. In general, the results of shrinkage test have shown reduction in shrinkage of internally cured self-compacting concrete as compared with reference concretes and this reduction increases with increase in the thermostone aggregate content-within-self-compacting-concrete.
The influence of recycled concrete aggregate on the properties of concrete
Authors: Mohammed Nisreen , Sarsam Kaiss , Hussien Mazin
Published: May 2018

Use of Recycled Coarse Aggregate (RCA) in concrete can be described in terms of environmental protection and economy. This paper deals with the mechanical properties of concrete compressive strength, splitting tensile strength, modulus of elasticity, and modulus of rupture. Three kinds of concrete mixtures were tested, concrete made with Natural Coarse Aggregate (NCA) as a control concrete and two types of concrete made with recycled coarse aggregate (50% and 100% replacement level of coarse recycled aggregate). These kinds of concrete were made with different targets of compressive strength of concrete f ’c (35MPa) and (70 MPa). Fifty specimens were tested of the fresh and hardened properties of concrete. The waste concrete from laboratory test cubes was crushed to produce the Recycled Coarse Aggregate used in recycled concrete. A comparative between the experimental results of the properties for fresh and hardened concrete is presented in the paper. Recycled aggregate concrete (RCA) had a satisfactory performance despite the replacement ratios. It was found using the size of Recycled Coarse Aggregate (RCA) of (5-14) mm has quite similar in performance with the same size of Natural Coarse Aggregate (NCA), it is necessary to use high quality of recycled concrete (with low levels of impurities). Recycled aggregate as an alternative to natural aggregates -seems quite successful.
Effect of silica fume/binder ratio on compressive strength development of reactive powder concrete under two curing systems
Authors: Abed Mohammed , Nasr Mohammed , Hasan Zaid
Published: May 2018

This paper aims to investigate the influence of Silica fume proportion ratio in respect to the total amount of binder on compressive strength of reactive powder concrete cured in two curing systems. Four ratios of Silica fume (0%, 15%, 25% and 35%) as replacement of cement weight were considered. After de-molding, two curing systems were used: the first included immersing the cubic specimens in water at 24 ± 2°C until the test. In the second, the specimens were immersed in hot water at 105 ± 5°C (accelerated curing) for 48 hours, then in water at 24 ± 2°C until the test. The results show that mix which contains 25% Silica fume imparts more enhancement on compressive strength as compared to the control mix. Also, it was found that the second system of curing has more influence on compressive strength development than the first one, especially at earlier ages.
Physical and mechanical characteristics of sustainable self-consolidating concrete incorporating high volume fly ash and cement kiln dust
Authors: Aldikheeli Mohammed , Salih Shakir , Al-Zwainy Faiq
Published: May 2018

In recent years, sustainable development has become a global issue and several industries (including concrete industry) have made every effort to reduce the high material cost, high energy depletion and CO2 emission in addition to soundly eliminate industrial waste residue. The purpose of this study is to investigate the possibility of production sustainable self-consolidating concrete (SSC) with green materials: Portland limestone cement (PLC), high volume class F fly ash (HVFA) and locally available cement kiln dust (CKD) depending on the limitations of fresh properties that is specified by ACI 273R-07 and EFNARC and to assess the effects of these green materials on the hardened properties. Moreover, microstructure of this concrete was also investigated by means of scanning electron microscopy (SEM). The results displayed that by replacing high levels of cement by type F fly ash and locally available CKD, it was conceivable to make eco-friendly SCC, satisfying the rheological demands for self-consolidating, with agreeable 28-day compressive strength.
Effects of nano and micro size of clay particles on the compressive and tensile strength properties of self-consolidating concrete
Authors: Alrashedi Baydaa , Hassan Maan
Published: May 2018

Many past studies concerned about using of nanoclay (nC) particles as an active pozzolan to concrete and their influence on the physical and mechanical properties. In this study, the effects of various nanoclay particle sizes and dosages on the compressive and flexural tensile strengths of SCCs were investigated. Progressive nC percentages of 2%, 5% and 8% were replaced with cements and the produced SCCs were evaluated and compared with similar replacement levels of the metakaolin MK which have comparable chemical compositions. The produced SCCs were tested for compressive, flexural tensile and splitting tensile strengths in 28 and 90 days. Results indicated that nC replacement harmed all the studied mechanical properties at 28 days age. After 90 days, however, both compressive and tensile strengths of nC concretes show superior strengths than control concrete and also exceeded MK concretes made of equivalent replacement levels. This behavior demonstrates the pozzolanic activity of the nC particles at later ages and proved to be significantly more effective than early ages.
Identification and analysis of factors affecting labour productivity in Iraq
Authors: Khaleel Tareq , Nassar Yasser
Published: May 2018

Productivity is a very important element in the estimation process in construction management. The objective of this research is to identify and analyze the factors which affect labor productivity in construction projects. In this research, 42 effective factors were collected from site survey, interview with engineers and experts, and previous research in the Arab world. These factors are grouped into Nine categories “Workforce, Leadership, Motivation, Supervisors, Safety, Project, Time, Material, and External”. A survey questionnaire of 70 respondents was distributed among different experts. A statistical analysis was done using SPSS and EXCEL packages. The Relative Importance Index was used to find out the most significant factors affecting the labor productivity in construction sites. The results accomplished from the survey revealed that the major factors negatively affect the labor productivity (ranked from the worst factor with Relative Importance Index values, respectively) namely, Availability Material (88.571%), Climate status “Weather” (88%), Religious occasions (86.29%), Number of working groups (86%), Ganger experience (85.714%), Workforce surveillance (84.857%), Ganger Age (84%), working at height (82%), Drawings and specifications alteration during execution (81.69%), and Sequence of floor (80.571%). Based upon these findings, this can help the construction professionals to improve the productivity and project performance in Iraq.
The relationship between the coefficient of discharge and the scour hole depth generated due to the combined flow over weir and below gates
Authors: Khassaf Saleh , Omran Hassan , Abdulabbas Fadhel
Published: May 2018

In this research, a study was conducted experimentally to investigate the scour hole dimensions downstream the combined structures which consist of weir and gate due to the effect of the coefficient of discharge (Cd) due to flow above the compound weir to the flow under the gate. Fifteen models have been designed, and every model is formed from composite weir consisting of two geometric shapes with rectangular gate of constant dimensions. In this study, the experiment was conducted in a laboratory channel was constructed from blocks and concrete with length of 18 m, 1 m width and depth of 1 m, where the laboratory models were installed after 7 m from the main gate which controlled the passage of water from the main reservoir into the flume. At the beginning, the calibration process was conducted to identify the actual discharge values that pass in the flume, and then seventy-five experiments were conducted in order to derive the formulae for investigating the non-dimensional depth (SD/d50) and non-dimensional length (SL/d50) of the scour hole due to the effect of (Cd). The bed of the flume was spread with sand layer of 30 cm thick for a distance of 4 m downstream combined structure. Two samples of sand were used in the experiments with different median size of particles (d50), the first of 0.7 mm and the second of 1 mm. Using the Excel program 2017, Six polynomial relationships were derived to calculate the dimensionless scour depth (SD/d50) in terms of the coefficient of discharge (Cd), where the resultant coefficients of determinations (R2) from these relationships were high.