bluuebunny/crossref_metadata_2025 huggingface dataset:
Interaction between Scale Inhibitors and Shale and Sandstone Formations
Authors: Yan Fei , Zhang Fangfu , Bhandari Narayan , Liu Ya , Wang Lu , Dai Zhaoyi , Zhang Zhang , Bolanos Valerie , Kan Amy , Tomson Mason
Published: April 2015

The reactions between scale inhibitors and formation minerals determine the inhibitor retention and release after inhibitor squeeze treatment and hydraulic fracturing. Scale inhibitor is an important ingredient in fracturing fluids to prevent mineral scale depositions during fracturing, shut-in and flowback stages. The interaction of scale inhibitors between carbonate formation is well understood but the interaction of scale inhibitors between shale and sandstone formation has not been investigated thoroughly. The primary objective of this study is to develop mechanistic understanding of interactions between scale inhibitors and shale and sandstone minerals.

In this study, adsorption and precipitation of a phosphonate scale inhibitor – DTPMP on shale minerals were investigated at 70°C. Equilibrium adsorption isotherms were determined for various inhibitor concentrations at different pH values. At low phosphonate concentration, the interaction between inhibitors and shale can be characterized as surface adsorption; at high phosphonate concentrations, inhibitors precipitate with cations released from shale minerals. The interaction of scale inhibitor and sandstone formation was evaluated in coreflooding experiments by repeated squeeze and acid treatment. The inhibitor return of an identical second DTPMP squeeze showed almost the same return curve as the first squeeze. An acidizing pretreatment demonstrated improvements in squeeze performance. It is proposed that acid treatment dissolves soluble minerals such as calcite, and DTPMP inhibitors forms less soluble precipitate such as iron phosphonate in the formation, which results in the enhancement of squeeze. The dissolution rate constant of DTPMP precipitate was determined at three different temperatures and the established relationship can be used to predict rate constant under other temperature conditions.

The insights presented in this work will help to understand the fate of phosphonate scale inhibitor in shale and sandstone reservoirs, manage the use of scale inhibitor in fracturing fluids, and design optimum scale squeeze packages for scale control in oil field.
Ferrous Iron Impact on Phosphonate and Polymeric Scale Inhibitors at Temperature Ranging from 25 to 70°C
Authors: Zhang Zhang , Zhang Fangfu , Wang Qiliang ‘Luke’ , Bhandari Narayan , Yan Fei , Liu Ya , Dai Zhaoyi , Wang Lu , Bolanos Valerie , Kan Amy T. , Tomson Mason B.
Published: April 2015

Ferrous iron (Fe2+) is one of the most common cations existing in oil and gas production water. Most Fe2+ ions come from dissolution of siderite in reservoir and corrosion of steel pipes. Compared to Ca2+ and Mg2+, Fe2+ has a higher complex stability constant with some common inhibitor function groups like phosphonate and carboxyl due to its transition metal structure. Therefore, understanding the influence of Fe2+ on inhibitors is important to enhance inhibition performance. Work still remain to be done to understand the effect of Fe2+ on scale inhibition, including a systematic study of the Fe2+ influence on phosphonate and polymeric scale inhibitors at different pH, values and molar ratios. Little research has been done at temperatures above room temperature, probably due to the difficulty of developing strictly anoxic test apparatus. In this study, a new anoxic laser apparatus is designed to test inhibitor performance. This newly designed apparatus features constant Argon gas headspace purging during an experiment to guarantee a strict maintenance of anoxic condition. This anoxic apparatus is based on laser detection method of nucleation induction time. It is easy to operate and enables experiments to be conducted at temperatures up to 200°F.
High Temperature, High Performance Water-Based Drilling Fluid for Extreme High Temperature Wells
Authors: Galindo Kay A. , Zha Weibin , Zhou Hui , Deville Jay P.
Published: April 2015

High performance (HP) water-based drilling fluids are particularly advantageous compared to conventional water-based systems because they provide faster penetration rates, enhanced hole cleaning, greater shale inhibition, and improved wellbore stability. Most high performance water-based drilling fluids only tolerate operating temperatures up to 300°F because they depend on biopolymer-based viscosifiers. Deeper exploration in extreme high temperature reservoirs (>300°F) requires new drilling fluid technologies. A new high performance, high temperature water-based drilling fluid that is both thermally and rheologically stable at 400°F was developed to meet these demands.

A novel synthetic polymer was developed for use in a new HP water-based mud (WBM). The new fluid system was hot rolled at 150°F for 16 hours to condition the fluid before testing. The conditioned fluids were subjected to dynamic or static aging conditions, with temperatures ranging from 300 to 400°F. The viscosity and pH values were determined with a direct indicating viscometer and pH meter, respectively. The Anton Paar viscosity was measured using the CC. 27 cup and bob geometry. The fluid loss properties of the fluids were determined by high pressure/high temperature (HP/HT) filtration at 350°F according to the API recommended practice.

This paper provides an overview of the current high performance drilling fluid chemistry, as well as the detailed study of the high temperature, high performance water-based drilling fluid formulated with 10.0 to 17.0 lbm/gal densities that exhibits a stable rheological profile. For example, a 14.0 lbm/gal formulation aged at 150°F for 16 hours provided a plastic viscosity (PV) of 29 cp and a yield point (YP) of 22 lbf/100 ft2. After static aging for 48 hours at 400°F, the fluid provided a PV of 27 cp and YP of 24 lbf/100 ft2. The new fluid maintains viscosity, adequate suspension, low shear strengths, shale stability, and filtration control up to 400°F, and the fluid is resistant to contamination.

This clay-free system uses a novel synthetic polymer viscosifier and filtration control agent, enabling the removal of thermally labile biopolymers without the addition of clay-based viscosifiers; it is environmentally acceptable for both land and offshore drilling and can be formulated with either chloride containing or non-chloride containing salts. The new fluid formulation provides reliable thermal stability that can function in extreme high temperature wells, while preserving the benefits of HP water-based drilling fluids.
Recent Advances in Viscoelastic Surfactants for Improved Production from Hydrocarbon Reservoirs
Authors: Hull Katherine L. , Sayed Mohammed , Al-Muntasheri Ghaithan A.
Published: April 2015

Viscoelastic surfactants (VES) are used in upstream oil and gas applications, particularly hydraulic fracturing and matrix acidizing. A description of surfactant types is introduced along with a theoretical description of how they assemble into micelles, what sizes and shapes of micelles can be formed under different conditions, and finally how specific structures can lead to bulk viscoelastic solution properties. This theoretical discussion leads into a description of the specific VES systems that have been used over the last twenty years or so in improved oil recovery for upstream applications.

VES-based fluids have been used most extensively for hydraulic fracturing. They are preferred over conventional polymer-based fracturing fluid systems because they are essentially solids-free systems which have demonstrated less damage to the reservoir rock formation. Important advancements in VES have been made by introducing “pseudo-crosslinking agents” such as nanoparticles to enhance the viscosity. Fracturing fluid systems based on VES have also been improved recently by developing internal breakers to lower their viscosity in order to flow back the well. The flexibility of VES-based fluids has been demonstrated by their application as foamed fluids as well as their incorporation with brine systems such as produced water.

A second key area that has benefited from VES-based systems is matrix acidizing carbonated-based reservoirs. The viscosity of these VES-based fluids is mostly controlled by pH where, at low pH (low viscosity), the acid system flows easily and invades pore spaces in the formation. During acidizing, the acid is spent, and the pH and viscosity increase. Because the spent acid has higher viscosity, fresh acid is diverted to low permeability un-contacted zones and penetrates the rocks to form wormholes. A number of experimental studies and field applications to these effects have been performed and will be described here.

In order for VES-based fluids to play a more prominent role in the field, inherent limitations such as cost, applicable temperature range, and leak-off characteristics will need to continue to be addressed. If we can efficiently and economically overcome these issues, VES-based fluids offer the industry an excellent clean, non-damaging alternative to conventional polymer-based fluids.
A Highly Effective Corrosion Inhibitor Based on Gemini Imidazoline
Authors: Yang Jiang , Liu Xuan , Jia Shuai , Qin Wenlong , Yin Chengxian , Liu Chen
Published: April 2015

Corrosion inhibitors are widely used to control corrosion under the sweet and sour environments in oil and gas industries. More effective and environment friendly corrosion inhibitors need to be developed. This paper studies a new gemini imidazoline corrosion inhibitor, which two hydrocarbon chains and two headgroups are linked by a rigid spacer. The gemini imidazoline was synthesized through the reaction of oleic acid with triethylene tetramine at 2:1 molar ratio. The product was characterized by infrared spectroscopy, chromatography and mass spectroscopy. The performance of the gemini imidazoline on inhibition of CO2 corrosion was evaluated by linear polarization resistance in sparged beaker testing. Rotating wheel testing was performed to evaluate the film persistency of the test inhibitors. The results showed that corrosion inhibition of the gemini imidazoline was more effective at lower concentration than that of conventional imidazoline. The gemini imidazoline mixed with fatty acid also showed better film persistency than that of conventional imidazoline. The emulsion tendency of the gemini imidazoline was less than that of conventional imidazoline. The mechanism of the highly effective gemini imidazoline was studied. It showed that gemini imidazoline has much higher surface activity than that of conventional imidazoline. The critical micelle concentration is several times lower than that of conventional imidazoline. Hence, the new gemini imidazoline (GIM) corrosion inhibitor and its mixture give more effective corrosion inhibition at low concentration, which also has less environmental impact.
Development Of A Very Low Peroxide Containing Peracid Formulation As Superior Treatment Option For Water Reuse Applications
Authors: Balasubramanian Ramakrishnan , Ryther Robert , De Paula Renato , Epps Brian , Keasler Victor , Li Junzhong , Staub Richard
Published: April 2015

The shale gas and oil wells drilled and completed in the United States in 2013 alone consumed about 1.8 billion gallons of water. With the increase in gas exploration, through natural and unconventional production, this consumption rate and need for water will increase dramatically. A recent study estimates about 3-6 million gallons of water per frac with volumes as high as 10 million reported for some areas. This increasing demand for water necessitates its reuse and development of critical technologies that aide in water treatment and reuse.

In the last few years, peracetic acid treatment has distinguished itself as a safe water treatment as well as a superior, cost effective biocide for water treatment applications. In addition, peracetic acid break down into environmentally safe components providing a low-risk option for routine water treatment in the oil and gas industry. One of the potential issues with the use of conventional peracetic acid is the presence of peroxide in the formulation that increases chances of incompatibility with cross-linked gel, friction reducers and scale inhibitors.

Nalco Champion’s new formulation, EC6779A, is an EPA registered biocide that increases the ratio of peracetic acid to peroxide. This new formulation allows for a rapid microbial kill in addition to its increased compatibility with most cross-linked gel packages while maintaining all the advantages of a traditional peracetic acid formulation. This reduced peroxide formulation also increases the stability of the peracetic acid, does not require an onsite generation, and kills bacteria usually associated with microbial induced corrosion (SRB, APB and GHBs), in addition to greatly reducing oxygen induced corrosion in oilfield systems. The new formulation is also dispensable using existing peracid systems and has proved to be a very safe and cost competitive alternative to chlorine dioxide.
Evaluation of Ferrous Carbonate/Iron Oxides Scaling Risk under High Temperature in the Absence and Presence of Scale Inhibitors
Authors: Yan Chao , Huang Jin , Guraieb Paula , Tomson Ross C.
Published: April 2015

Scale control in ultra-deepwater under high temperature, high pressure and high total dissolved solids (TDS) is critical for efficient and safe oil and gas production. With the continued development of offshore production in ultra-deepwater, more and more wells are exposed to extremely high temperature (>150 °C) and pressure (>15,000 psig) under anoxic condition. However scale testing, prediction and control under these extreme conditions is often challenging due to the limitation of testing equipment to accurately simulate these environments.

The dynamic tube blocking test is a widely applied test approach for evaluating scale risk and scale inhibition efficiency in the laboratory. However, little information has been reported for studying control and inhibition of siderite (FeCO3), a major product from corrosion. Furthermore, very few studies assess the scaling risk of iron oxides under extremely high temperatures.

In this research, the kinetics of siderite nucleation and precipitation has been studied in the absence and presence of scale inhibitors including sulphonated polycarboxylic acid (SPCA), polyvinyl sulphonate (PVS), carboxymethyl inulin (CMI) and sodium citrate. Scale inhibitors have been evaluated at high temperature (up to 250 °C) to determine if they are applicable for siderite (or iron oxide) inhibition. Inhibition of iron oxide precipitation under 250 °C and 600 psig was observed.

All solutions used in this research are strictly anoxic with ≪ 1 parts per billion (ppb) of dissolved oxygen and in the absence of added reducing reagents, that might alter the reaction. This strictly anoxic condition is critical for evaluating inhibition efficiency and degradation of scale inhibitors due to the interferences and reactions between dissolved oxygen and scale inhibitors.
Polyethersulfone (PES)/Cellulose Acetate Butyrate (CAB) Hybrid Hollow Fiber Membranes for Organic Matter Removal from Produced Water
Authors: Zha Shangwen , Yu Jianjia , Zhang Guoyin , Liu Ning , Lee Robert
Published: April 2015

In the United States, for every barrel of oil, approximately seven barrels of water are produced. Produced water consists of various amounts of organic and inorganic constituents from the source geologic formation and associated hydrocarbons. Produced water handling has become a major effort of all waterflood operations. Membrane technology has been widely used for produced water purification due to its economic and portable properties. However, the presence of organic matter in produced water causes serious membrane fouling, which shortens membrane life and increases operation costs. In this study, to reduce organic components in produced water, we fabricated a series of polyethersulfone (PES)/cellulose acetate butyrate (CAB) hybrid hollow fiber membranes (HFMs) for the removal of organic matters (benzene, toluene, octanoic acid and hexanoic acid) from produced water. The morphology of the hybrid PES/CAB hollow fiber membranes was characterized by scanning electron microscope (SEM) and atomic force microscope (AFM). The performance of the hybrid PES/CAB hollow fiber membranes was evaluated in terms of pure water flux, organic matter separation efficiency, flux decline ratio and flux recovery ratio. The results of our study reveal that the PES/CAB hybrid hollow fiber membranes showed an open-ended selective layer with homogenous CAB distribution. Compared to the pure PES hollow fiber membrane, the hybrid hollow fiber membranes improved the pure water flux by 20.3%. Separation tests showed that the hybrid PES/CAB hollow fiber membranes exhibited high separation efficiency of up to 99.8%. With 1.74 wt. % of CAB presented in the PES dope solution, the hybrid PES/CAB hollow fiber membranes possessed the lowest flux decline ratio and highest flux recovery ratio, indicating the excellent antifouling ability of the PES/CAB hollow fiber membranes. Based on these results, the PES/CAB hybrid hollow fiber membranes could serve as an attractive alternative for removing organic matter from produced water.
Effective Scale Prevention Using Chemically Infused Proppant - A Uinta Basin Case History
Authors: Leasure Joshua G. , Duenckel Robert J. , Hebert Jeff
Published: April 2015

Scale deposition down hole is a well-known and common production problem throughout the industry. Successful treatment of scale where it is first deposited near wellbore can be challenging in many cases, and sometimes impossible in others. While production assurance and scale inhibition chemicals have traditionally been added as a liquid in the fracturing fluid, this approach is often not very efficient or effective as a standalone inhibition strategy. Quite often a significant fraction of the chemical immediately returns during the initial flow back with only a small portion remaining for future inhibition. This then typically necessitates reapplication of the inhibitor chemicals using a squeeze treatment or continuous injection.

The chemical delivery system described here utilizes porous ceramic proppant, which has been infused with the appropriate production chemical(s) and encapsulated. The infused ceramic proppant is added at a designed small weight fraction to the rest of the proppant volume in the fracture treatment. It is manufactured to perform as both a proppant and a chemical delivery system so it replaces an equivalent volume of standard proppant in its dual function as a proppant [Duenckel, 2014]. After placement in the fracture the chemical slowly releases from the proppant over the designed treatment period. This chemical delivery system allows for a large amount of chemical to be placed within the fracture, releasing slowly, without negatively impacting conductivity. The proppant is encapsulated with a semipermeable membrane which controls the release of production chemicals during placement and production. This provides long term scale protection and production assurance which eliminates the need for additional costly well treatments and lowers overall lease operating expense.

In addition to describing the chemical delivery system, this paper will present a case history in which five wells in the Uinta Basin were treated with scale inhibitor using this new delivery system. In this application the infused porous ceramic was added in at a design fraction to natural frac sand treatments. Inhibitor returns will be presented which illustrate the efficient, long term protection of the entire production system from both barium sulfate and calcium carbonate scale.

This paper will be useful for all production and completions engineers and technicians who are engaged in providing long term scale prevention and production assurance.
Spatio‐temporal Variations of Dissolved Organic Matter in a German Forested Mountainous Headwater Catchment
Authors: Bol Roland , Lücke Andreas , Tappe Wolfgang , Kummer Sirgit , Krause Martina , Weigand Susanne , Pütz Thomas , Vereecken Harry
Published: April 2015

The dissolved organic matter (DOM) quality or quantity of stream waters reflects catchment functioning. Dissolved organic matter features, pH, and Fe content in the main stream and tributaries of the forested Wüstebach catchment in Germany were examined for a 4‐yr weekly sampling period (2009–2013). The catchment outlet (Wu14) discharge (Q) ranged from 0.22 to 72.5 L s−1, with minima and maxima around the summer and winter seasons, respectively. Discharge clearly followed precipitation in the late autumn to early spring period. Dissolved organic C (DOC) values at Wu14 ranged between 0.8 and 7.4 mg L−1, with a mean of 2.7 mg L−1. Annual periodicities in DOC and temperature (T), and DOC and Fe concentrations were positively correlated, reflecting DOM transport via organo‐mineral complexes. The watershed tributaries dominated by surficial water (Wu01, Wu08, and Wu09) exhibited relatively high DOC, Fe, pH, and specific DOC UV absorbance (SUVA) and high variability. Groundwater‐dominated tributaries (Wu03, Wu12, and Wu15) had lower, less variable contents. The extremely dry 2011 spring had limited effect on stream water chemistry. Outlet (Wu14) stream water DOC reflected seasonally variable contributions of surficial water and groundwater, annually 65 vs. 35%. Critically, a 4‐yr lowering of SUVA (reduction of the DOM aromaticity and increased biodegradability) was observed in headwater tributaries (Wu01 and Wu08) but not at Wu14. Our long‐term spatial‐temporal explicit data set, covering both tributaries and main stream water DOM quality and quantity, was critical in apportionment of contributing sources and drivers of sub‐ and whole‐catchment stream water DOM dynamics.
Greenhouse gas emissions from sludge treatment reed beds
Authors: Cui Yubo , Zhang Shunli , Chen Zhaobo , Chen Rui , Deng Xinnan
Published: April 2015

Sludge treatment reed bed systems (STRBs) are considered as an alternative technology for surplus sludge treatment. Organic matter is decomposed by various microbial reactions, resulting in gases such as CO2 and CH4 emitting into the atmosphere. The aim of this study is to investigate gas emission from STRBs. The static transparent chamber was adopted to measure gas emission; it allows sunlight to enter and plants to photosynthesise. The comparison of total solids and volatile solids showed STRBs have a higher efficiency in dewatering and mineralization than a conventional unplanted sludge drying bed (USDB). The CO2 emission ranged from 28.68 to 100.42 g CO2 m−2 d−1 in USDB, from 16.48 to 65.18 g CO2 m−2 d−1 in STRBs; CH4 emission ranged from 0.26 to 0.99 g CH4 m−2 d−1 in USDB, from 0.43 to 1.95 g CH4 m−2 d−1 in STRBs. Both gas fluxes decreased towards the end of vegetation and reached the highest rates during the hot and dry summer. After the system was loaded by sludge, the fluxes of CO2 and CH4 significantly decreased in the USDB, whereas they increased in STRBs. In terms of CO2 equivalent, the global warming potential of CH4 was 13.13 g CO2eq m−2 d−1 and 15.02 g CO2eq m−2 d−1 in USDB and STRBs, respectively.
Application of lipase from Burkholderia cepacia in the degradation of agro-industrial effluent
Authors: Mello Bueno Pabline Rafaella , de Oliveira Tatianne Ferreira , Castiglioni Gabriel Luis , Soares Júnior Manoel Soares , Ulhoa Cirano Jose
Published: April 2015

This study aimed to analyze the physical and chemical characteristics of Amano PS commercial lipase – Burkholderia cepacia and lipase produced by Burkholderia cepacia strain ATCC 25416, in addition to studying the hydrolysis of agro-industrial effluent collected in a fried potato industry. The optimum temperature for increasing lipase activity was 37 °C. The temperature increase caused a decrease in thermostability of lipase, and the commercial lipase was less stable, with values of 10.5, 4.6 and 4.9%, respectively, lower than those obtained by lipase from strain ATCC 25416, at temperatures of 40, 50 and 60 °C. The enzymatic activity was higher in alkaline conditions, achieving better results at pH 8.0. The pH was the variable that most influenced the hydrolysis of triacylglycerides of the agro-industrial effluent, followed by enzyme concentration, and volume of gum arabic used in the reaction medium. Thus, it can be observed that the enzymatic hydrolytic process of the studied effluent presents a premising contribution to reduction of environmental impacts of potato chip processing industries.
Optimization for extracellular polymeric substances extraction of microbial aggregates
Authors: Zhu Liang , Yu Haitian , Liu Yimei , Qi Hanying , Xu Xiangyang
Published: April 2015

The extracellular polymeric substances (EPS) are important macromolecular components in microbial aggregates. The three EPS extraction methods – ultrasound + cation exchange resins (CER) + sulfide, ultrasound + formamide + NaOH, and ultrasound + heat – were investigated in the study, and the component differences of extracted EPS from the loose flocs and dense aerobic granules were compared using chemical analysis and three-dimensional excitation-emission matrix (3D-EEM). Results showed that the contents of EPS were extracted effectively by ultrasound + formamide + NaOH and ultrasound + heat methods, and the ultrasound + CER + sulfide method did not extract the polysaccharides (PS) or protein (PN) contents from the sludge samples. The 3D-EEM analysis indicated that the nature of peak B/D, peak C/E/F, and peak A/G were attributed to PN-like, humic acid-like and fulvic acid-like fluorophores. All fluorophores can be detected from the EPS extracted through the ultrasound + heat method. Hopefully this will provide more information about the EPS interaction mechanism of microbial aggregates.
Modeling of organic substrate transformation in the high-rate activated sludge process
Authors: Nogaj Thomas , Randall Andrew , Jimenez Jose , Takacs Imre , Bott Charles , Miller Mark , Murthy Sudhir , Wett Bernhard
Published: April 2015

This study describes the development of a modified activated sludge model No.1 framework to describe the organic substrate transformation in the high-rate activated sludge (HRAS) process. New process mechanisms for dual soluble substrate utilization, production of extracellular polymeric substances (EPS), absorption of soluble substrate (storage), and adsorption of colloidal substrate were included in the modified model. Data from two HRAS pilot plants were investigated to calibrate and to validate the proposed model for HRAS systems. A subdivision of readily biodegradable soluble substrate into a slow and fast fraction were included to allow accurate description of effluent soluble chemical oxygen demand (COD) in HRAS versus longer solids retention time (SRT) systems. The modified model incorporates production of EPS and storage polymers as part of the aerobic growth transformation process on the soluble substrate and transformation processes for flocculation of colloidal COD to particulate COD. The adsorbed organics are then converted through hydrolysis to the slowly biodegradable soluble fraction. Two soluble substrate models were evaluated during this study, i.e., the dual substrate and the diauxic models. Both models used two state variables for biodegradable soluble substrate (SBf and SBs) and a single biomass population. The A-stage pilot typically removed 63% of the soluble substrate (SB) at an SRT <0.13 d and 79% at SRT of 0.23 d. In comparison, the dual substrate model predicted 58% removal at the lower SRT and 78% at the higher SRT, with the diauxic model predicting 32% and 70% removals, respectively. Overall, the dual substrate model provided better results than the diauxic model and therefore it was adopted during this study. The dual substrate model successfully described the higher effluent soluble COD observed in the HRAS systems due to the partial removal of SBs, which is almost completely removed in higher SRT systems.
Decreased UV absorbance as an indicator of micropollutant removal efficiency in wastewater treated with ozone
Authors: Wittmer A. , Heisele A. , McArdell C. S. , Böhler M. , Longree P. , Siegrist H.
Published: April 2015

Ozone transforms various organic compounds that absorb light within the UV and visible spectra. UV absorbance can therefore be used to detect the transformation of chemicals during ozonation. In wastewater, decolourisation can be observed after ozonation. This study investigates the correlation of the UV absorbance difference between the ozonation inlet and outlet and the removal efficiency of micropollutants in wastewater. The absorbance at 254 and 366 nm was measured at the ozonation inlet and outlet, as was the concentration of 24 representative micropollutants and the dissolved organic carbon (DOC). The results clearly showed that the relative decrease of absorbance (ΔAbs) is positively correlated with the relative removal efficiency of micropollutants. We therefore suggest that UV absorbance can be used as a feedback control parameter to achieve optimal ozone dosage in wastewater treatment plants and to gain a fast insight into the process efficiency and stability of the ozonation.
Role of vegetation (Typha latifolia) on nutrient removal in a horizontal subsurface-flow constructed wetland treating UASB reactor–trickling filter effluent
Authors: da Costa Jocilene Ferreira , Martins Weber Luiz Pinto , Seidl Martin , von Sperling Marcos
Published: April 2015

The main objective of the work is to characterize the role of plants in a constructed wetland in the removal of nitrogen (N) and phosphorus (P). The experiments were carried out in a full-scale system in the city of Belo Horizonte, Brazil, with two parallel horizontal subsurface-flow constructed wetland units (one planted with Typha latifolia and one unplanted) treating the effluent from a system composed of an upflow anaerobic sludge blanket reactor and a trickling filter (TF). Each wetland unit received a mean flow of approximately 8.5 m³ d−1 (population equivalent around 60 inhabitants each), with a surface hydraulic loading rate 0.12 m3m−2d−1. The experiments were conducted from September 2011 to July 2013. Mean effluent concentrations from the wetlands were: (a) planted unit total nitrogen (TN) 22 mg L−1, ammonia-N 19 mg L−1, nitrite-N 0.10 mg L−1, nitrate-N 0.25 mg L−1, P-total 1.31 mg L−1; and (b) unplanted unit TN 24 mg L−1, ammonia-N 20 mg L−1, nitrite-N 0.54 mg mL−1, nitrate-N 0.15 mg L−1, P-total 1.31 mg L−1. The aerial part of the plant contained mean values of 24.1 gN (kg dry matter)−1 and 4.4 gP (kg dry matter)−1, and the plant root zone was composed of 16.5 gN (kg dry matter)−1 and 4.1 gP (kg dry matter)−1. The mean extraction of N by the plant biomass was 726 kgN ha−1y−1, corresponding to 17% of the N load removed. For P, the extraction by the plant biomass was 105 kgP ha−1y−1, corresponding to 9% of the P load removed. These results reinforce the reports that N and P removal due to plant uptake is a minor mechanism in horizontal subsurface-flow constructed wetlands operating under similar loading rates, typical for polishing of sanitary effluent.
The effects of different aeration modes on ammonia removal from sludge digester liquors in the nitritation–anammox process
Authors: Sobotka D. , Czerwionka K. , Makinia J.
Published: April 2015

The aim of this study was to determine the impact of continuous and intermittent aeration on the rate of ammonia removal in the combined nitritation–anammox process. This process was run in two parallel sequencing batch reactors (SBRs), with a working volume V = 10 L, treating sludge digester liquors from the Gdansk (Poland) wastewater treatment plant (WWTP). The ammonia oxidizing bacteria were cultivated from activated sludge from the same plant, whereas the anammox bacteria originated from the Zurich WWTP (Switzerland). Both SBRs were operated with 12-h cycles, temperature 30 °C and hydraulic residence time between 1 and 7 days depending on the operating period. The maximum specific ammonium utilization rate (sAUR) was observed in the reactor with intermittent aeration, and varied in the range of 4.4–4.7 g N kg VSS−1 h−1. The sAUR in the reactor with continuous aeration was slightly lower and ranged from 4.39 to 4.41 g N kg VSS−1 h−1. In the case of intermittent aeration, the additional measurement was performed at two different dissolved oxygen concentrations, i.e., 1 and 0.8 mg O2 L−1, and the observed nitrogen removal rates were 4.7 and 2.7 g N kg VSS−1 h−1, respectively.
The combination of coagulation, acid cracking and Fenton-like processes for olive oil mill wastewater treatment: phytotoxicity reduction and biodegradability augmentation
Authors: Yazdanbakhsh Ahmadreza , Mehdipour Fayyaz , Eslami Akbar , Maleksari Hajar Sharifi , Ghanbari Farshid
Published: April 2015

Olive oil mill wastewater (OOMW) is one of the most important industrial wastewaters in the world due to high organic load and phenolic compounds. In this study, an integration of three processes including coagulation, acid cracking and Fenton-like was evaluated to treat OOMW. The performance of alum, ferric chloride and polyaluminum chloride was studied as coagulants. Among coagulants, ferric chloride showed the best results in comparison with the others. Coagulation process with FeCl3 removed 91.2% chemical oxygen demand (COD), 91.3% phenol, 98.9% total suspended solids and 99.2% turbidity at condition of pH = 6 and 3,000 mg/L coagulant dosage. Acid cracking process following the coagulation process with ferric chloride could slightly degrade organic compounds and provided suitable condition for the next process. Fenton-like process with zero valent iron (ZVI) was applied after coagulation and acid cracking. The optimal removal efficiency was achieved by Fenton-like process which was accomplished in condition of 7 g/L ZVI, 1,000 mg/L H2O2 and 180 min reaction time. The biodegradability of final effluent of this integration was improved significantly and biochemical oxygen demand5/COD value increased from 0.14 to 0.83. The results of germination tests revealed that phytotoxicity of the final effluent decreased.
Prevalence and change of malocclusions from primary to early permanent dentition: A longitudinal study
Authors: Dimberg Lillemor , Lennartsson Bertil , Arnrup Kristina , Bondemark Lars
Published: April 2015

Objective: 

To follow a group of children from primary to early permanent dentition and determine the prevalence, self-correction, and new development of malocclusions; the need for orthodontic treatment; and the possible influences of habits, breathing disturbances, and allergies.

Materials and Methods: 

Two hundred and seventy-seven children were followed at 3, 7, and 11.5 years of age. Malocclusions and orthodontic treatment need were determined by clinical examinations. Data on sucking habits, breathing disturbances, allergies, dental trauma, and orthodontic treatments were collected from a questionnaire and dental records.

Results: 

Malocclusions were found in 71% of participants at 3 years of age, 56% at 7 years of age, and 71% at 11.5 years of age. Self-correction was noted for anterior open bite, sagittal malocclusions, and posterior crossbite, while deep bite developed. A high number of contact point displacements and spacings contributed to the prevalence of malocclusion rate of 71% at 11.5 years. Severe or extreme orthodontic treatment need was apparent in 22%. Habits, allergies, or breathing disturbances found at 3 years of age had no associations with malocclusions at 11.5 years of age.

Conclusions: 

This sample revealed a significant percentage of malocclusions and orthodontic treatment need. A substantial number of self-corrections and establishment of new malocclusions occurred during the transition from primary to early permanent dentition.
Laser cutting of carbon fiber-reinforced plastic with an absorber transparent for visible spectrum
Authors: Canisius M. , Herzog D. , Schmidt-Lehr M. , Oberlander M. , Direnga J. , Emmelmann C.
Published: April 2015

Mass production of carbon fiber-reinforced plastic parts has lately started in the automotive industry. Due to no abrasive wear in combination with a high degree of automation and ability for 3D processing, laser remote cutting is a suitable method for machining purposes in this context. In the automotive environment, solid-state lasers are favored because optical waveguides may then be used. In turn, the low absorption of the radiation of such lasers in the matrix material presents a drawback in terms of comparatively large heat affected zones (HAZ) and flaking at the cutting kerf. This paper deals with the question, if a laser absorbing additive can be used to enhance the absorption within the matrix material, while the optical properties in the visible spectrum are kept. For this purpose, an additive known from laser transmission welding has been added to the matrix material. Cutting experiments have been carried out while varying concentration of the additive. The investigations show that a significant reduction of the mean HAZ of 25% and the standard deviation (1 σ) of 56% can be achieved by adding 4% w/w of the additive to the resin. In addition to that, the flaking behavior can be avoided. Compared to adding soot particles, the optical properties of the laminate do not change in the visible spectrum, leaving the fiber textile visible.
Study of die break strength and heat-affected zone for laser processing of thin silicon wafers
Authors: Finn Daragh S. , Lin Zhibin , Kleinert Jan , Darwin Michael J. , Zhang Haibin
Published: April 2015

As semiconductor based devices are manufactured on ever thinner silicon substrates, the required associated die break strength has to increase commensurately to maintain pick yields. In this study, the influence of laser processing parameters on the die break strength in laser dicing of silicon oxide-coated silicon wafers and silicon-based memory devices is investigated experimentally using ultraviolet lasers spanning a wide range of pulse width, from 400 fs to 150 ns. It is found that the net fluence, an accumulated pulse energy per surface area, is a meaningful process metric for damage induced by heat-affect zone to compare lasers processes with a large variety of pulse widths, laser scan speed, average powers, and repetition rates. Optimized process conditions for both nanosecond and femtosecond pulse widths are identified for achieving the highest die break strength in the target devices. The dependence of heat-affected zone on pulse width and net fluence during nanosecond laser processing is further demonstrated using multiphysical simulations. Simulations suggest that the thickest heat-affected zone section during laser scribing is typically located at the boundary of the laser incident surface. Simulation results also show that for a given repetition rate the heat-affected zone becomes larger as the net fluence increases due to smaller interpulse separation, consistent with the experimental observation.
Géographie de l'islamisme politique en Algérie : essai d'interprétation à partir des élections de 1990 et 1991 (Geography of political islamism in Algeria : interpretations from the 1990 and 1991 polls)
Authors: Brulé Jean-Claude , Fontaine J.
Published: April 2015

Résumé. - Les élections algériennes de 1990 et 1991 ont vu une nette victoire du Front Islamique du Salut, encore qu'il ait perdu plus d'un million de voix entre les deux scrutins. Ce vote protestataire plus que d'adhésion aux valeurs intégristes, a été général sur l'ensemble du territoire algérien à de rares exceptions près. Mais son intensité a été variable : c'est dans les régions les plus déstructurées (par la colonisation, le modèle de développement ou l'émigration récente et brutale) qu'il a obtenu ses plus francs succès, que ce soit en milieu rural ou en banlieue. Inversement il n'a pu percer dans les espaces à forte identité (Kabylie amazigh, M'zab, pays targui). Entre ces espaces bien tranchés, on trouve toute une gamme de cas où l'islamisme politique a plus ou moins bien réussi à s'implanter.
TIRADS for sonographic assessment of hypofunctioning and indifferent thyroid nodules
Authors: Rink T. , Zimny M. , Schenke S.
Published: April 2015

Aim: To test the feasibility of the Thyroid Imaging Reporting And Data System (TIRADS) according to Horvath and Kwak for the assessment of thyroid nodules. Patients, method: Retrospective analysis of patients with thyroid nodules applying the following inclusion criteria: B-mode-ultrasound, surgery and histological results. Thyroid nodules were classified as TIRADS 2, 3, 4A, 4B, 4C, 5 and 6. Results: A total of 172 patients were included (133 women, 48 ± 13 years, 39 men, 49 ± 11 years) with 222 thyroid nodules (24.9 ± 11.5 mm). Final histological diagnosis revealed 203 benign nodules (91%) and 19 malignant nodules (9%; 18 papillary thyroid carcinoma, PTC, and one medullary thyroid carcinoma, MTC). One hundred and sixty thyroid nodules were hypofunctioning in 99mTc-pertechnetate-scintigraphy, 14 nodules were hyperfunctioning and 46 nodules were classified as indifferent. In two cases with small carcinoma < 1 cm 99mTc-pertechnetate- scintigraphy was not performed. According to Horvath, the prevalence of malignancy was 6.7% in TIRADS 2, 0% in 3, 1.9% in 4A, 33% in 4B, 12.5% in 5 and 100% in 6; 73 nodules (39%) were not clearly classifiable, including 3 carcinoma (4.1%). According to Kwak, the prevalence of malignancy was 6.9% in TIRADS 2, 0% in 3, 2% in 4A, 4.1% in 4B, 23.1% in 4C, and 100% in 5 and 6, respectively. Notably, in the subgroup of hot nodules, 11 (79%) were graded as TIRADS 4A or higher, and thus advisable for fine-needle aspiration biopsy in both TIRADS. Conclusion: The TIRADS described by Horvath is not practicable due to numerous unclassifiable nodules. The revised TIRADS published by Kwak is feasible and suitable to assess the prevalence of malignancy, but it cannot replace scintigraphic imaging. Fine-needle-biopsy is not necessary in nodules categorized as (K)TIRADS 3, 4A and 5.
Exogenous Adult Postmortem Neural Precursors Attenuate Secondary Degeneration and Promote Myelin Sparing and Functional Recovery following Experimental Spinal Cord Injury
Authors: Carelli Stephana , Giallongo Toniella , Marfia Giovanni , Merli Davide , Ottobrini Luisa , Degrassi Anna , Basso Michele D. , Di Giulio Anna Maria , Gorio Alfredo
Published: April 2015

Spinal cord injury (SCI) is a debilitating clinical condition, characterized by a complex of neurological dysfunctions. Neural stem cells from the subventricular zone of the forebrain have been considered a potential tool for cell replacement therapies. We recently isolated a subclass of neural progenitors from the cadaver of mouse donors. These cells, named postmortem neural precursor cells (PM-NPCs), express both erythropoietin (EPO) and its receptor. Their EPO-dependent differentiation abilities produce a significantly higher percentage of neurons than regular NSCs. The cholinergic yield is also higher. The aim of the present study was to evaluate the potential repair properties of PM-NPCs in a mouse model of traumatic SCI. Labeled PM-NPCs were administered intravenously; then the functional recovery and the fate of transplanted cells were studied. Animals transplanted with PM-NPCs showed a remarkable improved recovery of hindlimb function that was evaluated up to 90 days after lesion. This was accompanied by reduced myelin loss, counteraction of the invasion of the lesion site by the inflammatory cells, and an attenuation of secondary degeneration. PM-NPCs migrate mostly at the injury site, where they survive at a significantly higher extent than classical NSCs. These cells accumulate at the edges of the lesion, where a reach neuropile is formed by MAP2- and β-tubulin III-positive transplanted cells that are also mostly labeled by anti-ChAT antibodies.
Paracrine Effects of Mesenchymal Stem Cells Induce Senescence and Differentiation of Glioblastoma Stem-Like Cells
Authors: Kološa Katja , Motaln Helena , Herold-Mende Christel , Koršič Marjan , Lah Tamara T.
Published: April 2015

Glioblastoma multiforme (GBM) displays high resistance to radiation and chemotherapy, due to the presence of a fraction of GBM stem-like cells (GSLCs), which are thus representing the target for GBM elimination. Since mesenchymal stem cells (MSCs) display high tumor tropism, we examined possible antitumor effects of the secreted factors from human MSCs on four GSLC lines (NCH421k, NCH644, NIB26, and NIB50). We found that conditioned media from bone marrow and umbilical cord-derived MSCs (MSC-CM) mediated cell cycle arrest of GSLCs by downregulating cyclin D1. PCR arrays revealed significantly deregulated expression of 13 genes associated with senescence in NCH421k cells exposed to MSC-CM. Among these, ATM, CD44, COL1A1, MORC3, NOX4, CDKN1A, IGFBP5, and SERPINE1 genes were upregulated, whereas IGFBP3, CDKN2A, CITED2, FN1, and PRKCD genes were found to be downregulated. Pathway analyses in GO and KEGG revealed their association with p53 signaling, which can trigger senescence via cell cycle inhibitors p21 or p16. For both, upregulated expression was proven in all four GSLC lines exhibiting senescence after MSC-CM exposure. Moreover, MSC paracrine signals were shown to increase the sensitivity of NCH421k and NCH644 cells toward temozolomide, possibly by altering them toward more differentiated cell types, as evidenced by vimentin and GFAP upregulation, and Sox-2 and Notch-1 downregulation. Our findings support the notion that MSCs posses an intrinsic ability to inhibit cell cycle and induce senescence and differentiation of GSLCs.
Continuous Improvement after Multiple Mesenchymal Stem Cell Transplantations in a Patient with Complete Spinal Cord Injury
Authors: Jarocha Danuta , Milczarek Olga , Wedrychowicz Anna , Kwiatkowski Stanislaw , Majka Marcin
Published: April 2015

Interruption of spinal cord (SC) continuity leads to functional loss below the lesion level. The purpose of this study was to evaluate the safety and efficacy of bone marrow nucleated cell (BMNC) and multiple mesenchymal stem cell (MSC) transplantations in spinal cord injury (SCI). A patient with total SC interruption at the Th2-3 level underwent experimental therapy with BMNC and MSC transplantations followed with intensive neurorehabilitation treatment. At admission, 6 h after SCI, the patient was scored ASIA A, had a Th1 sensation level, paraplegia with sphincter palsy, and was without the ability to control trunk movement. Neurophysiology examination showed bilateral axonal damage to the motor and sensory neural fibers with no motor unit potentials or peripheral motor nerve conduction in the lower extremities. The standard therapy had been applied and had not produced any positive results. The patient was treated with autologous BMNCs injected intravenously (3.2 × 109) and intrathecally (0.5 × 109) 10 weeks after the SCI and with five rounds of MSCs every 3-4 months (1.3-3.65 × 107) administered via lumbar puncture. Total number of transplanted MSC cells during the course of treatment was 1.54 × 108. There were no complications related to transplantations and no side effects related to the therapy during 2 years of treatment. The ASIA score improved from A to C/D (from 112 to 231 points). The sensation level expanded from Th1 to L3-4, and the patient's ability to control the body trunk was fully restored. Bladder filling sensation, bladder control, and anal sensation were also restored. Muscle strength in the left lower extremities improved from plegia to deep paresis (1 on the Lovett scale). The patient's ability to move lower extremities against gravity supported by the movements in quadriceps was restored. The patient gained the ability to stand in a standing frame and was able to walk with the support of hip and knee ortheses. Magnetic resonance imaging (MRI) revealed that at the Th2/Th3 level, where the hemorrhagic necrosis was initially observed, small tissue structures appeared. Our results suggest that repeated intrathecal infusions of MSCs might have the potential to produce clinically meaningful improvements for SCI patients.