bluuebunny/crossref_metadata_2025 huggingface dataset:
A Sulfur-Free and Biodegradable Gel Stabilizer for High Temperature Fracturing Applications
Authors: Chetan Prakash , Songire Sumit
Published: September 2015

For a successful hydraulic fracturing operation, two of the most important properties required from fracturing fluids are transport proppant into the fractured zone and minimum damage to formation and proppant pack conductivity. As the fluid is pumped downhole, it experiences thermal and shear thinning. Shear recovery and thermal stability are critical in terms of successful fracture creation and proppant placement. These fluid properties can be controlled by proper selection of crosslinker and linkable groups. Thermal stability of fluid at high temperatures can be increased by proper selection of gel stabilizers and it also reduces the amount of gelling agent to be used. Conventional gel stabilizer contains sulfur which could contribute to H2S gas when consumed by sulfate reducing bacteria. H2S gas is not only corrosive in nature but also harmful to health and thus, although it performs well, several operators seek sulfur-free stabilizers that can perform equivalent to sulfur-based compounds.

This paper describes a sulfur-free gel stabilizer developed for enhancing the stability of fracturing fluid, allowing a lower concentration of gelling agent. This gel stabilizer is sulfur-free, nonhazardous, and biodegradable. It also provides better stability for fluids compared to conventional sulfur containing gel stabilizers.

Further showcased is the improvement in stability of crosslinked fracturing fluid using the sulfur-free stabilizer under high temperature (HT) conditions of 280 to 320°F. Rheological tests performed using a Chandler high-pressure/high-temperature (HP/HT) viscometer with and without stabilizer are discussed. Results shows a significant change in terms of fluid stability in the presence of this new stabilizer as it provides better stability compared to conventional sulfur containing stabilizer. Also, shear sensitivity tests performed under multiple high shear rate cycles between 100-935-1700 s-1 showed excellent shear recovery after every high shear cycle by completely rehealing in less than 30 seconds.
Solving Swelling Clay Issues in Egypt's Western Desert: Combination of Fluid Engineering and Steel-Body PDC Bit Displaces Roller Cone in Large Hole Section
Authors: Ahmad M. F. , Hussein M.. , Abd El-Azm H. M. , Hanafy O.. , Eloufy M.. , Ibrahim S.. , Aguib K.. , Farouk A. A. , Sabry M. A.
Published: September 2015

Drilling the top hole section in Egypt's Western Desert has proven to be a challenge because finding the optimal balance of drilling speed, pulling out of hole without issue, and running the casing without clay swelling is critical. Historically, a standard milled-tooth (MT) bit, slick BHA, and top hole mud system were used for economic considerations. Recently, a problem arose when drilling a 17½-in surface hole in the Western Desert Moghra sand and Dabaa area, where the formation is composed of swelling clays that caused delays and cost increases.

The solution to combat clay swelling would require an effective mud strategy; a PDC design that could increase ROP and resist balling while remaining economic; and a slick BHA that ensured hole verticality without the aid of directional tools and minimizes the affect of drillstring dynamics for prolonged PDC bit life. The intent of such optimization is providing enough buffer time for the casing to be run without problems, and the overall solution needs to be more economic than the previous drilling practice.

An integrated BHA, bit design, and mud strategy were deployed in a field test with outstanding results. The results showed a step-change in ROP performance and allowed a trouble-free hole. The PDC bit and slick BHA successfully mitigated vibrations and maintained verticality. The application of customized drilling fluid formulation that contained high-performance shale stabilizers with the redesigned mud-weight schedules and early fluid displacement resulted in significant enhancements in tripping while drilling as well as in running and cementing the 13⅜-in casing.
Technical Training Assessment – a Tool to Upgrade Competencies in an Upstream Oil & Gas Company
Authors: Al-Daihani Eisa Hadi , Nandi Arun Kumar , Raza Syed , Varshney Avinash
Published: September 2015

Measuring technical training effectiveness is an enormous challenge worldwide. It is difficult to create a common model or tool kit to measure and determine the efficiency and return on training investment. Therefore, many organizations have developed their own unique customized assessment system to meet their needs.

In most of the Upstream Oil & Gas Companies, this task is outsourced. Generally, the assessment tool kits available to determine the training efficiency are based on only one or two elements i.e. participant's feedback or instructor's feedback which does not reflect clear picture and transparency of all activities of the event and eventually it has direct impact on knowledge gaps and desired competencies.

The present paper has come out with a model where four different key success elements are identified and measured through 4 dimensions (Participants, in-house Assessors, Instructors and QA team). Reasonable weightage are given to each element i.e. Planning, Training Providers' effort, Participants' effort and Environment. The final efficiency results is then compared with knowledge Gaps filled (Post-Pre). If the efficiency and gaps filled are in same swing OR close to each other, then it is considered as accurate and representative assessment. This ensures a more accurate and transparent process.

Additionally, the summary of Learning Objectives Achievements are thoroughly analysed and communicated the existing gaps to concerned members to ensure that they are filled with other resources (coaching or OJTs). Also the outcome of the assessment is shared with concerned training providers to address the issues eliminate these shortfalls in future training events for better efficiency and effectiveness.
Successful Application of Plug and Hydrajetting Technique during Multistage Fracture for Horizontal Wells with CT
Authors: Ortiz Jose Ramon , Montes Efrén , Hernandez Miguel , Castillo Hazael Abner , Carbone Salvatore
Published: September 2015

This paper presents an alternative for operators regarding tools and methods using coiled tubing (CT) during the implementation of horizontal completions.

To help address challenges faced developing horizontal completions, both cemented liners and open holes have been widely used in conventional and unconventional reservoirs. Various completion techniques have evolved from traditional tubing conveyed perforation (TCP) and plug setting, and hydrajet assisted fracturing has become the preferred pumpdown technique within the last six years in northern Mexico.

The criteria used to determine the completion technique is based on three parameters—extension of horizontal length developed [well geometry, dogleg severity (DLS), deviation], fracture design (pump rate, number of intervals) and type of reservoir being exploited. For the case discussed, a pumpdown technique was selected.

Pumpdown techniques are considered one of the fastest completion techniques to provide mechanical isolation between fracture stages; nevertheless, it has not been completely effective during all stages. Some of these techniques can cause premature setting of bridge plugs because of poor sand displacement or adverse well geometries, including high DLS. During the application of this technique, CT interventions are primarily considered in the event of contingencies, such as screenouts (sand cleanout) and plugs prematurely setting (plug millouts).

Even though no completion operation is immune to contingencies and associated costs and nonproductive time (NPT), a constant repetition of them because of inherent well conditions or poor fluid admission by the formation increases associated completion costs and diminishes equipment efficiency in place (frac set, logging unit).

As a result, CT has become an effective solution with the development of new tools and techniques to avoid such contingencies. This paper develops the concept “plugging and jetting,” wherein a mechanical isolation bridge plug (BP) is placed with CT, allowing abrasive perforations to help the producing formation communicate with the wellbore in a single run, thus allowing reduction of NPT up to 30% and providing a new alternative for horizontal completions.

This paper presents case histories with benefits and results. Bottomhole assembly (BHA) design considerations with improvements that provide a new alternative to operators are also presented. This method allows completion of fracturing stages in a continuous manner, thus being advantageous in terms of operational time reduction and consequently cost savings.
Correlation of Rock Mechanic Properties with Wireline Log Porosities through Fulla Oilfield - Mugllad Basin -Sudan
Authors: khair Elham Mohammed , Zhang Shicheng , Abdelrahman Ibrahim Mustafa
Published: September 2015

The current study presents elastic properties model for Fulla Oilfield in northeast of Block 6 in south of Sudan. Due to the poor formation consolidation and relatively viscose fluid, reservoirs may predictably produce massive amounts of sand and numerous troubles were found in the field as a result of sanding. No documented researches were found to introduce good parameters for rock strength and rock failure conditions through the field. Therefore, an accurate technique for predicting rock failure conditions may yield good profits and improve the economic returns through preventing sand production from the formations.

General correlations were presented to accurately describe rock strength parameters for the field; the work utilizes the application of the wireline porosities to be used as a strength indicator through the combination of rock mechanical theories with the characterization of Fulla oilfield. Log porosities (density, sonic and neutron) were calibrated with the core measured porosity, and the best matching porosity were correlated with the dynamic calibrated strength parameters by different correlations.

The results support the evidence of the use of porosity as an index for mechanical properties; power functions were found more reliable than the exponential functions, and can be used with a high degree of confidence; also it is more accurate than the Shale Index model presented in pre-vious work for same field; however, the result does not support the direct linear expression pre-sented in the literature for other field due to the variations in the field conditions.
Structural, Stratigraphic Geology and Pressure Compartmentalization of Feradus Field Based on 3-D Seismic Data and Subsurface Geology
Authors: Mira A.. , Meshref W.. , Radwan Amr M. , Mostafa A.. , Rayan A.. , Hassanin M.. , Saad A..
Published: September 2015

Field development plan is an integration among Geophysical, Geological, Petrophysical and Reservoir Engineering data.

The 3D seismic and wellbore data confirm that the field is composed of complex structures with variable of oil-water contact and differences in pressure surveys.

A major source of these variations is compartmentalization, which is defined as limitation on the ability to produce hydrocarbons resulting from permeability barriers within a field. Two primary causes of compartmentalization. These are Stratigraphic and Structural variations in permeability.

Ferdaus field is located in East Abu Gharadig basin in Western Desert, Egypt. It produces oil from Cretaceous sandstones mainly from three reservoirs: Middle, Lower Abu Roash “G” (A/R “G”) members and Upper Bahariya Formation.

In Ferdaus field, Middle and Lower Abu Roash “G” members were deposited as barrier bars according to which the effects of the lateral and vertical sand facies changes within the productive sand intervals, have very limited impact on the pore connectivity based on Electric logs and mud log data. Therefore; the stratigraphic variations were neglected..

Structural compartmentalization, fault properties can constrain the fluid flow and pressure development, thus affecting decisions associated with the selection of the drainage strategy within reservoir management activities in order to maintain the pressure and increase the oil production rate.

By using 3D seismic data, electric logs and pressure data made it possible to sudivide the field into compartments which differ in number based on the reservoir level. This gave good estimates for the Original Oil In Place (OOIP) and reserves which leads to apply a good development plan by infill wells and/or increasing the productivity by applying secondary recovery project (water injection).
Certificate-based Fair Exchange Protocol of Schnorr Signatures in Chosen-key Model
Authors: Shao Zuhua , Gao Yipeng
Published: September 2015

This paper proposes the first optimistic protocol to accomplish the fair exchange of standard Schnorr signatures in the chosen-key model, in which each participant is allowed to choose his Schnorr key pair freely without showing his knowledge of the private key. Besides solving the authentication problem of public keys, the protocol relaxes excessive trust on the adjudicator since the adjudicator needs to be trusted only by the signer. The protocol is secure against three types of inside adversaries under the DL assumption in the random oracle model. It suits much more the actual circumstances of the Internet.
Enhanced Liver Fibrosis (ELF) Immunoassay Test for Identification of Significant Liver Diseases: Recent Developments
Authors: Giasuddin Rubayat Sheik , Khan Mobin , Giasuddin ASM , Siddiqui Md Mahmudur Rahman
Published: September 2015

Liver Fibrosis (LF) is a common outcome in chronic liver disease (CLD). Over a period of time, the process results in cirrhosis leading to disruption in functional capacity of liver. Further serious complications may occur including portal hypertension, liver failure and cancer. The magnitude of CLD has increased being recognized as a major cause for morbidity and mortality globally and it is increasing progressively in Bangladesh also. Question arises "Is the transabdominal needle biopsy of liver, the traditional reference standard method, sufficient and efficient enough for detecting and assessing liver fibrosis particularly in the early stages of significant liver disease?" More simpler, convenient and less expensive blood tests such as 'Enhanced Liver Fibrosis (ELF) immunoassay test', Fibrotest and Aspartate transaminase-platelet ratio index (APRI), have been developed and reported for identification of significant CLD and use as prognostic tool in clinical practice. Among them, the ELF test had been found to be statistically the best for diagnosing and predicting clinical outcomes in patients with CLD and may be a useful prognostic tool in clinical practice. This ELF immunoassay test has been briefly reviewed in this article. Short title: ELF immunoassay test for CLDAnwer Khan Modern Medical College Journal Vol. 6, No. 1: January 2015, Pages 38-41
A Case of Complicated Acute Type B Aortic Dissection
Authors: Chowdhury Mashhud Zia , Ghafoor Nusrat , Salauddin Mohammed , Iqbal Md Jabed , Siddiqui Md Mahmudur Rahman
Published: September 2015

A 65 year lady with chest and back pain was referred to our hospital with suspected case of acute coronary syndrome. A computed tomography (CT) aortic angiogram showed dissection of abdominal and thoracic aorta. Patient was initially treated by drugs for controlling heart rate and blood pressure with analgesics but due to progression of disease and involvement of left subclavian artery ostium referred for surgical intervention. She underwent left carotid-subclavian bypass and TEVAR (Thoracic endovascular aortic repair) with good outcome. The present case is a good demonstration revealing that in absence of clinical suspicion and diagnostic imaging, acute aortic dissection represents a diagnostic dilemma which requires immediate action.Anwer Khan Modern Medical College Journal Vol. 6, No. 1: January 2015, Pages 46-49
Challenges in Developing Applications for Aging Populations
Authors: Williams Drew Marie , Gani Md Osman , Addo Ivor D , Majumder AKM Jahangir Alam , Tamma Chandana P , Wang Mong-Te , Chang Chih-Hung , Ahamed Sheikh Iqbal , Chu Cheng-Chung
Published: September 2015

Elderly individuals can greatly benefit from the use of computer applications, which can assist in monitoring health conditions, staying in contact with friends and family, and even learning new things. However, developing accessible applications for an elderly user can be a daunting task for developers. Since the advent of the personal computer, the benefits and challenges of developing applications for older adults have been a hot topic of discussion. In this chapter, the authors discuss the various challenges developers who wish to create applications for the elderly computer user face, including age-related impairments, generational differences in computer use, and the hardware constraints mobile devices pose for application developers. Although these challenges are concerning, each can be overcome after being properly identified.
Branded entertainment: los contenidos de entretenimiento como herramienta de comunicación de marketing. Un estudio de su situación actual en España
Authors: De Aguilera Moyano Joaquín , Baños González Miguel , Ramírez Perdiguero Francisco Javier
Published: September 2015

En el nuevo contexto de marketing surgen herramientas de comunicación como el branded entertainment; un tipo de mensaje híbrido con elque las marcas producen contenidos de entretenimiento. Metodología: Este estudio tiene como objetivo mejorar el conocimiento del branded entertainment y su situación en España así como sus expectativas de futuro. Se ha realizado una investigación exploratoria utilizando como técnica metodológica la entrevista en profundidad aplicada a un grupo de expertos en creación y distribución de branded entertainment. Resultados y conclusiones: Los resultados muestran: existe un amplio conocimiento de sus posibilidades como técnica de comunicación comercial; los contenidos producidos deben ser relevantes para competir con otros productos de entretenimiento; se espera un notable incremento en su utilización ante la pérdida de eficacia de las tácticas intrusivas; y se percibe como la herramienta de comunicación más adecuada para generar engagement del consumidor.
Effect of Geometric Conservation Law on Improving Spatial Accuracy for Finite Difference Schemes on Two-Dimensional Nonsmooth Grids
Authors: Mao Meiliang , Zhu Huajun , Deng Xiaogang , Min Yaobing , Liu Huayong
Published: September 2015

It is well known that grid discontinuities have significant impact on the performance of finite difference schemes (FDSs). The geometric conservation law (GCL) is very important for FDSs on reducing numerical oscillations and ensuring free-stream preservation in curvilinear coordinate system. It is not quite clear how GCL works in finite difference method and how GCL errors affect spatial discretization errors especially in nonsmooth grids. In this paper, a method is developed to analyze the impact of grid discontinuities on the GCL errors and spatial discretization errors. A violation of GCL cause GCL errors which depend on grid smoothness, grid metrics method and finite difference operators. As a result there are more source terms in spatial discretization errors. The analysis shows that the spatial discretization accuracy on non-sufficiently smooth grids is determined by the discontinuity order of grids and can approach one higher order by following GCL. For sufficiently smooth grids, the spatial discretization accuracy is determined by the order of FDSs and FDSs satisfying the GCL can obtain smaller spatial discretization errors. Numerical tests have been done by the second-order and fourth-order FDSs to verify the theoretical results.
Ocean acidification does not affect magnesium composition or dolomite formation in living crustose coralline algae, Porolithon onkodes in an experimental system
Authors: Nash M. C. , Uthicke S. , Negri A. P. , Cantin N. E.
Published: September 2015

Abstract. There are concerns that Mg-calcite crustose coralline algae (CCA), which are key reef builders on coral reefs, will be most susceptible to increased rates of dissolution under higher pCO2 and ocean acidification. Due to the higher solubility of Mg-calcite, it has been hypothesised that magnesium concentrations in CCA Mg-calcite will decrease as the ocean acidifies, and that this decrease will make their skeletons more chemically stable. In addition to Mg-calcite, CCA Porolithon onkodes, the predominant encrusting species on tropical reefs, can have dolomite (Ca0.5Mg0.5CO3) infilling cell spaces which increases their stability. However, nothing is known about how bio-mineralised dolomite formation responds to higher pCO2. Using P. onkodes grown for 3 and 6 months in tank experiments, we aimed to determine (1) if mol % MgCO3 in new crust and new settlement was affected by increasing CO2 levels (365, 444, 676 and 904 μatm), (2) whether bio-mineralised dolomite formed within these time frames, and (3) if so, whether this was effected by CO2. Our results show that there was no significant effect of CO2 on mol % MgCO3 in any sample set, indicating an absence of a plastic response under a wide range of experimental conditions. Dolomite within the CCA cells formed within 3 months and dolomite abundance did not vary significantly with CO2 treatment. While evidence mounts that climate change will impact many sensitive coral and CCA species, the results from this study indicate that reef-building P. onkodes will continue to form stabilising dolomite infill under near-future acidification conditions, thereby retaining its higher resistance to dissolution.
Grensarbeiders en het recht op werkloosheidsuitkeringen: de zaak Mertens
Authors: Niesten H.
Published: September 2015

Het Hof van Justitie van de Europese Unie heeft in het arrest Mertens geoordeeld dat een grensarbeider die in directe aansluiting op een voltijds arbeidscontract deeltijds werkzaam wordt bij een andere onderneming in dezelfde lidstaat gedeeltelijk werkloos is. Een situatie van volledige werkloosheid is slechts aan de orde indien de betrokken werknemer volledig heeft opgehouden te werken.

HvJ 5 februari 2015, C-655/13, Mertens, ECLI:EU:C:2015:62
Uitsluiting van homoseksuele mannen als bloeddonor: het arrest Léger en de Nederlandse praktijk
Authors: Dute J.C.J. , Swarte A.
Published: September 2015

Verschillende lidstaten, waaronder Nederland en Frankrijk, sluiten mannen die seksueel contact hebben (gehad) met mannen levenslang uit als bloeddonor. Het Hof van Justitie heeft zich op 29 april 2015 uitgesproken over deze permanente uitsluiting van MSM en heeft voorwaarden geformuleerd waaraan in dat geval moet zijn voldaan.

HvJ 29 april 2015, zaak C-528/13, Geoffrey Léger/Ministre des Affaires sociales, de la Santé et des Droits des femmes, en Établissement français du sang, ECLI:EU:C:2015:288
NOCA-1 functions with γ-tubulin and in parallel to Patronin to assemble non-centrosomal microtubule arrays in C. elegans
Authors: Wang Shaohe , Wu Di , Quintin Sophie , Green Rebecca A , Cheerambathur Dhanya K , Ochoa Stacy D , Desai Arshad , Oegema Karen
Published: September 2015

Non-centrosomal microtubule arrays assemble in differentiated tissues to perform mechanical and transport-based functions. In this study, we identify Caenorhabditis elegans NOCA-1 as a protein with homology to vertebrate ninein. NOCA-1 contributes to the assembly of non-centrosomal microtubule arrays in multiple tissues. In the larval epidermis, NOCA-1 functions redundantly with the minus end protection factor Patronin/PTRN-1 to assemble a circumferential microtubule array essential for worm growth and morphogenesis. Controlled degradation of a γ-tubulin complex subunit in this tissue revealed that γ-tubulin acts with NOCA-1 in parallel to Patronin/PTRN-1. In the germline, NOCA-1 and γ-tubulin co-localize at the cell surface, and inhibiting either leads to a microtubule assembly defect. γ-tubulin targets independently of NOCA-1, but NOCA-1 targeting requires γ-tubulin when a non-essential putatively palmitoylated cysteine is mutated. These results show that NOCA-1 acts with γ-tubulin to assemble non-centrosomal arrays in multiple tissues and highlight functional overlap between the ninein and Patronin protein families.
Chapter 4. The places of Franz Josef Land: current visits and imagery
Authors: Umbreit Andreas
Published: September 2015

Recent tourist cruises of Franz Josef Land have offered the chance to search for the remains of historic expeditions to the islands, as well as expeditions that used the islands as a base from which to try to reach the geographic North Pole.  Expedition leader Andreas Umbreit discusses his recent such finds at both Greely Island and Teplitz Bay on Rudolf Island, as well as several other sites.
Synthesis of nanostructured zirconia by anodization at low potentials
Authors: Hidalgo Jacqueline , Colet‐Lagrille Melanie , Mukasyan Alexander , Fuenzalida Víctor M. , Vargas Tomás
Published: September 2015

This work reports the synthesis of nanostructured ZrO2 by anodization of zirconium electrodes at potentials well below the range of 10–50 V used as a standard procedure. Zirconium was first anodized in a 1M (NH4)2SO4 electrolyte and then further anodized in the presence of fluoride ions added to the electrolyte as NH4F. The maximum potential applied to zirconium during the whole process was 1 V with respect to an Ag/AgCl (sat.) reference electrode. Amorphous films of ZrO2 consisting of nanopores and nanowire‐like structures were produced with this low‐potential methodology.
Losing your edge: climate change and the conservation value of range‐edge populations
Authors: Rehm Evan M. , Olivas Paulo , Stroud James , Feeley Kenneth J.
Published: September 2015

Populations occurring at species' range edges can be locally adapted to unique environmental conditions. From a species' perspective, range‐edge environments generally have higher severity and frequency of extreme climatic events relative to the range core. Under future climates, extreme climatic events are predicted to become increasingly important in defining species' distributions. Therefore, range‐edge genotypes that are better adapted to extreme climates relative to core populations may be essential to species' persistence during periods of rapid climate change. We use relatively simple conceptual models to highlight the importance of locally adapted range‐edge populations (leading and trailing edges) for determining the ability of species to persist under future climates. Using trees as an example, we show how locally adapted populations at species' range edges may expand under future climate change and become more common relative to range‐core populations. We also highlight how large‐scale habitat destruction occurring in some geographic areas where many species range edge converge, such as biome boundaries and ecotones (e.g., the arc of deforestation along the rainforest‐cerrado ecotone in the southern Amazonia), can have major implications for global biodiversity. As climate changes, range‐edge populations will play key roles in helping species to maintain or expand their geographic distributions. The loss of these locally adapted range‐edge populations through anthropogenic disturbance is therefore hypothesized to reduce the ability of species to persist in the face of rapid future climate change.
An evaluation of the Standardized Precipitation Index for assessing inter‐annual rice yield variability in the Ganges–Brahmaputra–Meghna region
Authors: Kattelus Mirja , Salmivaara Aura , Mellin Ilkka , Varis Olli , Kummu Matti
Published: September 2015

Climate variability has major impacts on crop yields and food production in South Asia. The spatial differences of the impact are not, however, well understood. In this study, we thus aim to analyse the spatio‐temporal relationship between precipitation and rice yields in the Ganges–Brahmaputra–Meghna region. The effects of rainfall variation on yields were analysed with regression models using the Standardized Precipitation Index (SPI) as an explanatory variable. Our results indicate that in large part of the study region, a strong relationship between precipitation and rice yields exists and the SPI at various lags chosen as the predictor variable performed well in describing the inter‐annual yield variability. However, the study demonstrated large spatial variations in the strength of this relationship or optionally in the suitability of the chosen methodology for investigating it. In the mid‐plains of the Ganges, which represent very important agricultural areas, precipitation variability has a strong impact on rice yields, while in downstream Ganges as well as in Brahmaputra, where precipitation is more abundant, the relationship was less pronounced. Where the performance of the regression models was weaker, it is likely that yield variation depended on other factors such as management practices or on other climate factors such as temperature. The results further showed that the SPI at 1, 3, 6 and 12 month lags calculated for the monsoon time (June–October) are most commonly the best at explaining the rice yield variability. The SPI can thus be considered a very useful predictor of rice yield variability in some parts of the study region, demonstrating that they could be used for agricultural applications and policy decisions to improve the region's food security.
Mechanical recoverability and damage process of ionic‐covalent PAAm‐alginate hybrid hydrogels
Authors: Xin Hai , Brown Hugh R. , Naficy Sina , Spinks Geoffrey M.
Published: September 2015

Hydrogels consisting of interpenetrating networks of ionically and covalently crosslinked polymers showed high toughness and mechanical recoverability as a result of the dissociation and re‐formation of ionic crosslinks. The present investigation aimed to provide a quantitative study on the mechanical recoverability and damage process of an example hybrid gel of calcium crosslinked alginate and covalently crosslinked polyacrylamide. Three series of load/unload tests were performed sequentially with the mechanical properties of the gel fully retrieved between the 2nd and 3rd load/unload series while only the partial recovery of mechanical properties was evident from the 1st to 2nd series. The load/unload curves in the three series were modeled by existing mechanical models, and the fitted model parameters clearly demonstrate a damage process for the hybrid gel. When a hybrid gel was deformed above its historic maximum strain, the shortest alginate chains were fully‐stretched, pulling apart the weak ionic crosslinks and dissipating fracture energy. Consequently, the strand density of the intact gel network was reduced and the contour length of the remaining next‐shortest load‐bearing alginate chains became longer. A log‐normal distribution was used to describe the probability distribution for the strand fracture and also to describe the strand length distribution of the ionic network. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016, 54, 53–63
Modeling of ribonucleic acid–ligand interactions
Authors: Stefaniak Filip , Chudyk Ewa I. , Bodkin Michael , Dawson Wayne K. , Bujnicki Janusz M.
Published: September 2015

Computational methods play a pivotal role in the early stages of small molecule drug discovery and are widely applied in virtual screening, structure optimization, and compound activity profiling. Over the past half century in medicinal chemistry, almost all the attention has been directed to protein–ligand binding and computational tools were created with such targets in mind. However, with growing discoveries of functional RNAs and their possible applications, RNA macromolecules have gained considerable attention as possible drug targets. This flow of discovery was followed by adapting existing computational tools for RNA applications as well as active development of new RNA‐tailored methods. However, due to the different nature of RNA, especially its tendency to use morphological plasticity (conformational change in ligand binding) this remains a challenging task. The evolution of ‘protein‐based’ drug discovery and related computational methods offers some clues on possible future directions and developments in modeling RNA interactions with small molecule ligands. WIREs Comput Mol Sci 2015, 5:425–439. doi: 10.1002/wcms.1226

This article is categorized under:

Structure and Mechanism > Computational Biochemistry and Biophysics

Computer and Information Science > Chemoinformatics

Molecular and Statistical Mechanics > Molecular Interactions
A Study on Dispersion and Antibacterial Activity of Functionalizing Multi‐walled Carbon Nanotubes with Mixed Surfactant
Authors: Bai Yu , Wang Cunyang , Gao Jingjun , Su Juan , Ma Wen
Published: September 2015

The dispersibility in aqueous phase and antibacterial activity of multi‐walled carbon nanotubes (MWNT) with mixed surfactant functionalization has been studied. The ratio of 3:7 between hexadecyltrimethylammonium bromide and octylphenol ethoxylate (TX100) showed the highest dispersing power for MWNT. The use of mixed surfactants formed stable MWNT dispersions at lower total surfactant concentration compared to their concentrations when used alone. UV–Vis spectroscopy, transmission electron microscopy and Fourier transform infrared spectroscopy were employed to characterize the dispersion of MWNT in the aqueous phase. The result indicated that the surfactant molecules had been successfully adsorbed onto the surface of the MWNT. Bacterial toxicity assay showed that the mixed surfactant‐functionalized MWNT had a strong antibacterial activity and concentration dependence to Staphylococcus aureus. Based on the consideration of the cost and environmental impact, the use of mixed surfactant (CTAB‐TX100) should be more favorable for the stable dispersion of MWNT and the improvement of antibacterial activity than that of an individual surfactant. These observations suggested that the mixed surfactant‐functionalized MWNT might be a promising antibacterial agent for removal and inactivation of biological contaminants in water treatment applications.
A New Potential Formula Applicable to Flattened Systems
Authors: Ninković S.
Published: September 2015

A new formula for the gravitational potential of flattened systems is proposed. It is a modification of the Miyamoto–Nagai potential and should be applied to very flattened systems, exponential discs as a typical example. The resulting rotation curve agrees sufficiently well with that obtained by using special functions and the total masses remain the same. The functions contained in the new term can improve the agreement for the rotation curve and also reduce the effect of negative density values which appear off the midplane.
Towards a Malayan Indian sonic geography: Sound and social relations in colonial Singapore
Authors: Sykes Jim
Published: September 2015

From the mid-1920s, Indian music scenes developed in Singapore that were not just about the construction of regional and religious forms of Indian diasporic belonging. Drawing upon European, Chinese and Malay influences (musical and otherwise), and performing in contexts that were uncommon in India, Singaporean Indian musicians contributed to non-Indian musics, while incorporating non-Indian influences into Indian genres. Such musical–communal interactions functioned in colonial Singapore to locate the island as a hub for the constitution of a ‘Malayan Indian sonic geography’. By encouraging links between various Indian and other communities throughout the peninsula via radio, films, recordings, touring networks, and performances at hotels and amusement parks, music became a means for Indian communication and integration in colonial Malaya — a sonic geography that would be significantly transformed, though not eliminated, after Singapore and Malaysia parted ways in 1965.
Trends and Determinants of Work-Retirement Transitions under Changing Institutional Conditions: Germany, England and Japan compared
Authors: HOFÄCKER DIRK , SCHRÖDER HEIKE , LI YUXIN , FLYNN MATTHEW
Published: September 2015

Many governments world-wide are promoting longer working life due to the social and economic repercussions of demographic change. However, not all workers are equally able to extend their employment careers. Thus, while national policies raise the overall level of labour market participation, they might create new social and labour market inequalities. This paper explores how institutional differences in the United Kingdom, Germany and Japan affect individual retirement decisions on the aggregate level, and variations in individuals’ degree of choice within and across countries. We investigate which groups of workers are disproportionately at risk of being ‘pushed’ out of employment, and how such inequalities have changed over time. We use comparable national longitudinal survey datasets focusing on the older population in England, Germany and Japan. Results point to cross-national differences in retirement transitions. Retirement transitions in Germany have occurred at an earlier age than in England and Japan. In Japan, the incidence of involuntary retirement is the lowest, reflecting an institutional context prescribing that employers provide employment until pension age, while Germany and England display substantial proportions of involuntary exits triggered by organisational-level redundancies, persistent early retirement plans or individual ill-health.
Fullones and Roman society: a reconsideration
Authors: Flohr Miko
Published: September 2015

Among the most significant material evidence for manufacturing and production activities in Roman towns are the remains of workshops dedicated to fulling. The layout of these so-called fullonicae is often relatively well preserved and provides detailed information about the daily activities in these workshops. Together with the remains of bakeries and a few other identifiable urban workshops, fullonicae allow us to discuss important aspects of the social and economic contexts of production in Roman cities. However, despite the potential of the evidence and the significance of the subject, there has been little discussion of Roman fulling, and the contribution of M. Bradley in JRA 15 (2002) 21-44 is only the second to discuss Roman fullonicae in general. Bradley focuses on the cultural and economic context of fullones (fullers) and fullonicae in Roman society. Although his narrative will prove to be a useful contribution to the debate on Roman fulling, there are good reasons to question some of his conclusions. A major objection concerns the uniformity of his approach. His highly conceptualised profile of the context of Roman fulling underestimates possible regional and chronological variations as well as the multiform nature of human society. Furthermore, he relies too heavily on literary sources and uses epigraphy and material remains merely to illustrate his suggestions. This leads to an over-simplification of the complex relations between various types of data. As I will argue below, these methodological problems seriously undermine his statements about the economic nature of the Roman fullonica, the spatial context of fullonicae, and the social status of fullones.
L'archéologue et le topographe sur la colline du Pincio: à propos du grand plan de Rome du Jubilé 2000
Authors: Jolivet Vincent , Broise Henri
Published: September 2015

But the city, in its corruption, refused to submit to the dominion of the cartographers, changing shape ai will and without warning…

S. Rushdie, The Satanic verses

Les plans et les vues cavalières ou panoramiques de Rome, à partir de celle de Paolino da Venezia, de peu postérieure à 1320, et jusqu'à la naissance de la cartographie moderne, considérée comme définitivement acquise avec le plan de Nolli de 1748, sont utilisés comme une source primordiale d'informations pour la topographie de la ville. Par rapport au prodigieux corpus de dessins laissés par les antiquaires de la Renaissance, ces documents présentent l'avantage de figurer l'insertion des différents monuments, même mineurs, dans le tissu urbain, mais souvent l'inconvénient, compte tenu l'échelle des cartes, de les représenter de manière moins détaillée, voire même purement symbolique. De plus, ils répondent à un certain nombre d'exigences, idéologiques ou pratiques, qui déterminent leur degré de fidélité par rapport au réel: le souci de mettre en évidence certains monuments (par exemple le long des itinéraires de pèlerinage), l'impact de la politique d'urbanisme d'un pontife, ou le système défensif de la ville, ont souvent porté à privilégier certains monuments, ou entraîné des changements de proportions entre les édifices figurés, parfois la suppression de quartiers d'habitations entiers; par ailleurs, le souci de rendre plus lisible le réseau viaire, et de dessiner les façades, a porté à l'élargissement des rues, et donc à des distorsions dans la représentation des bâtiments. Surtout, l'attitude de l'auteur de la carte par rapport à son objet à joué, à l'évidence, un rôle déterminant: pour un Bufalini, un Falda ou un Nolli, conscients de la nouveauté et de l'importance de leur projet, et qui y ont consacré de longues années de travail, combien de cartographes pressés, indifférents à la ville, simples compilateurs de leurs prédécesseurs?
Response to R. Tybout “Roman wall-painting and social significance”
Authors: Hallett C. H.
Published: September 2015

In his article in this issue, R. Tybout has some harsh words (38-39) for an article by S. Yerkes published in JRA 13. T.'s reaction seems to involve not so much a scholarly disagreement as a major misunderstanding of Yerkes' paper. I would like to offer a brief corrective to his comments.

T. seems under the impression that the identification of Vitruvius' monstra is the main — or only — point of Yerkes' essay. This is probably because of the title. The paper is a radically reduced presentation of the argument of the author's master's thesis which was entitled “Neo-Attic motifs in Roman painting”. And the identification of some of the sources for the monstra — as motifs in much earlier Roman marble furnishings — is actually the main thrust of her argument. Her original title for the article also included a reference to “neo-Attic motifs” but that was omitted by the editor after it was submitted to JRA. T. is dismayed that Yerkes fails to cite the chapter on Vitruvius 7.5.3 ff. in W. Ehrhardt's monograph Stilgeschichtliche Untersuchungen (T. 1, n.l). Now, Yerkes is well aware of this work and cites it in her thesis, together with another paper Ehrhardt published on “Vitruv und die zeitgenössische Wandmalerei” in KJb 1991. So she could — and perhaps should — have included Ehrhardt's work in her notes, as T. suggests; perhaps including fuller references to other past scholarship too. But T. goes on to make the extraordinary claim (38 n.30) that Ehrhardt's chapter renders Yerkes' observations “largely superfluous”. I cannot follow T. here, for Ehrhardt's essay actually has a quite different aim and focus; and the differences are worth underlining.
“Stress Control” as a Large Group Psychoeducational Intervention at Step 2 of IAPT Services: Acceptability of the Approach and Moderators of Effectiveness
Authors: Burns Paul , Kellett Stephen , Donohoe Gill
Published: September 2015

Background:“Stress Control” (SC) has been adopted as a core intervention in step 2 of Improving Access to Psychological Therapies (IAPT) services, but contemporary evidence of effectiveness has lagged behind service uptake.Aims:To investigate the acceptability and effectiveness of SC and to explore moderators of outcome.Method:Analysis of acceptability (via attendance rates) and effectiveness (via IAPT minimum dataset).Results:SC was well tolerated with 73.3% of all patients and 75.4% of “clinical cases” attending three or more sessions. Of the 546 “clinical cases” attending SC and not in receipt of other interventions, 37% moved to recovery. Attendance improved outcome; for those patients attending all SC sessions the recovery rate rose to 59.2%.Conclusion:SC appears a well-tolerated and effective intervention that enables large numbers to gain access to treatment in an organizationally efficient manner. Attendance is important in facilitating SC outcomes and research evaluating attendance interventions are needed.
Patterns of frontier development: a dynamic model of resource extraction in the Brazilian Amazon
Authors: Melstrom Richard T. , Jones Luke R. , Caviglia-Harris Jill
Published: September 2015

Developing countries are known to exploit their resource frontier to achieve growth objectives and reduce poverty. This can lead to long-term positive outcomes or – if resource exploitation is unsustainable – lose–lose outcomes that leave populations and ecosystems worse off. This paper introduces a dynamic model of resource exploitation to explain how regions may succumb to, avoid or escape this negative outcome. The theoretical model characterizes a frontier community that uses soil as an input into agricultural production. The model shows that there may be a critical point in the soil stock that determines whether agricultural activities lead to sustainable development or a collapse in local income. This suggests that, in the event of a resource collapse, temporary adjustments to the system may permanently rehabilitate the resource base and change a community's development pattern. Calibration of the model to several frontier states of the Brazilian Amazon points toward an overall outcome of steady development.
Australian Red Cross leadership in the promotion of international humanitarian law
Authors: McCormack Tim
Published: September 2015

Editor's note: In this Opinion Note, Tim McCormack highlights the Australian experience of setting up and developing an IHL programme domestically as an example of how IHL can be disseminated and promoted at the national level. The Australian experience is a great success story and can serve as an example for others seeking to do the same.
The Study of Process and the Nature of Explanation in Developmental Science
Authors: Witherington David C. , Heying Shirley
Published: September 2015

The question of “how” occupies center stage in the explanatory efforts of developmental science and establishes the study of process as the field's defining mission. In line with this mission, recent decades have witnessed a new wave of focus on taking seriously issues of time, variability, and context in the study of development. For many in the field, however, fully espousing a process orientation for developmental science requires an abandonment of the structural explanation in which the field is historically steeped—for example, the organizational sequencing and directionality established in the “grand theories” of classic developmental accounts. Metatheoretically, the idea that a process orientation actively conflicts with a structural orientation rests on the conceptual conflation of different kinds of structural explanation. Such conceptual conflation, in turn, derives from the adoption of an ontological framework that reduces all explanation to mechanistic antecedent–consequent relations. The purpose of this article is to frame developmental science's pursuit of the question of “how” within the broader context of metatheoretical division that characterizes the field's approach to explanation itself.