bluuebunny/crossref_metadata_2025 huggingface dataset:
Treatment of wastewaters contaminated with zinc ions using natural zeolite as adsorbent in a fixed bed column
Authors: Omar Waid S.
Published: December 2015

The potential of natural zeolite as a low-cost adsorbent was investigated for the removal of zinc from aqueous solution using a continuous fixed bed column. The zeolite tested was taken from the same source (Jabal Uniza in south Jordan) and subjected to crushing and sieving only, without any treatment. The two samples tested are UNZ1 (0.42–0.841 mm) and UNZ2 (0.21–0.42 mm). The Thomas model analysis of the measured breakthrough curves revealed that the adsorbent UNZ2 has a higher value of adsorption capacity to zinc ions (50.75 mg/g) than UNZ1 (33.68 mg/g). The time to 50% breakthrough was determined by the Yoon and Nelson model. It has been found that the time needed to reach 50% breakthrough is 2,006 minutes and 3,171 minutes for UNZ1 and UNZ2, respectively. This indicated that UNZ2 provides better performance with larger service time. Both UNZ1 and UNZ2 agreed to a high degree with the Thomas and Yoon and Nelson models.
Extraction behavior of Cr(VI) and coexistence with interfering ions by trialkylamine
Authors: Li Yingxue , Cui Chongwei
Published: December 2015

Solvent extraction of chromium(VI) with trialkylamine (N235) using kerosene/n-heptane as the diluent was investigated. The basic conditions for Cr(VI) extraction have been explored, and the influence of coexisting contaminants on extraction has been evaluated. The results indicated that the separation of Cr(VI) could be realized with N235, and the recovery rate could be increased by adding organophosphorus-tributyl phosphate as the modifier due to the strong bonding force of synergistic extraction. However, the inorganic phosphorus could inhibit the chemical reaction between tertiary amine and Cr(VI) ions owning to the competition of the limited adsorption sites. Besides, inorganic anions such as massive SO42− and NO3− could inhibit extraction of metal ions because of competition coordination. In addition, the separation of Cr(VI) from coexisting metal ions could be achieved with trialkylamine except Fe2+ due to its reducibility. Based on the results, the feasibility of pseudo-emulsion based hollow fiber strip dispersion used for separation and recovery of Cr(VI) has been evaluated, and the transport properties of Cr(VI) and coexistence with interfering ions have been explored.
Adding value to wastewater by resource recovery and reformulation as growth media: current prospects and potential
Authors: Zacharof M.-P. , Lovitt R. W.
Published: December 2015

Wastewater, despite being a serious environmental constraint, has been identified as a source of valuable commodities including phosphate, ammonia, metal ions and volatile fatty acids. Using low-cost physical pre-treatments, filtration technology gives the opportunity of recovering materials in purified concentrated liquid form and purified water. Filtration also allows manipulation of the nutrient content in the effluents enabling the formulation of a series of streams enriched with important chemical components, enabling their reformulation into balanced nutrient media for microbial growth and the production of biofuels, acids and other chemicals such as lipids and enzymes. This approach benefits industry through the use of a relatively abundant inexpensive feedstock able to be recycled to produce high value chemicals while reducing the carbon footprint of the fermentation and reducing waste disposal. Examples of potential schemes of nutrient formulation and their application are presented.
Sewage sludge treatment: evaluation of the energy potential and methane emissions with COD balancing
Authors: Schaum C. , Lensch D. , Bolle P.-Y. , Cornel P.
Published: December 2015

Sewage sludge is an important resource for the generation of electricity and heat within a wastewater treatment plant (WWTP). Taking a holistic approach to such use involves considering the greenhouse gas emissions. In particular, for anaerobic sludge treatment, methane emissions are a matter of concern. Therefore, the utilization of a carbon balance, based on the chemical oxygen demand (COD), will be a focus for evaluating the magnitude of methane losses within the sludge treatment. In addition to biogas production and use in combined heat and power plants (CHPs), dissolved methane in digested sludge, as well as the methane slip, have to be considered. Measurements of dissolved methane concentrations in sewage sludge from digesters of various WWTPs show a concentration of about 17–37 mg CH4/L. The COD balance indicates a ratio of the methane emissions (methane slip, dissolved methane and residual gas) of < 4% of the total methane production during digestion. Considering the electricity generation by CHPs and the higher global warming potential of methane, compared to carbon dioxide, emissions of approximately 300 g CO2-equ./kWhel result, which is in a similar range to greenhouse gas emissions caused by electricity generation by fossil fuels.
An Australian perspective on DPR: technologies, sustainability and community acceptance
Authors: Law Ian B.
Published: December 2015

Australia has had guidelines in place for water recycling (for all uses other than potable reuse) since 2006. These guidelines were extended in May 2008 to cover potable reuse and have since been applied to two potable reuse schemes – one in Brisbane (Queensland) in 2011 and the second in Perth (Western Australia) in 2013. These guidelines cover both indirect potable reuse and direct potable reuse (DPR) and outline the steps that must be followed in the planning and validation of such schemes. This paper summarizes: (i) recent work carried out in Australia on treatment trains and technologies suitable for DPR; (ii) sustainability considerations of DPR and how it compares with other water supply options; and (iii) developments in community education and engagement in the potable reuse space.
Fe and Mn removal from mining drainage using goaf filling materials obtained from coal mining process
Authors: Zhang Liping , Chen Aolei , Qu Hongbin , Xu Shouqiang , Zhang Xue , He Xuwen
Published: December 2015

Coal gangue, sandy soil and clay (mass ratio 45:4:1) as goaf filling materials acquired from coal mining processes were applied to remove Fe and Mn effectively from mining drainage. The results of an adsorption kinetic study showed that the Fe adsorption equation was y = 21.454y + 8.4712, R2 = 0.9924 and the Mn adsorption equation was y = 7.5409x + 0.905, R2 = 0.9957. Meanwhile, the goaf filling materials had low desorption capacity (Fe 6.765 μg/g, Mn 1.52 μg/g) and desorption ratio (Fe 8.98%, Mn 11.04%). Experiments demonstrated that Fe and Mn from mining drainage could be removed stably at a flow rate of 1.2 L/min, Fe inlet concentration of less than 40 mg/L, Mn inlet concentration of less than 2 mg/L and neutral or alkaline conditions. During a procedure of continuous experiments, the effluent quality could meet the requirement of the ‘Code for Engineering Design of Sewage Regeneration-GB503352-2002’. A real-application project using goaf filling materials to treat mining drainage in Shendong coal mine showed that the average cost per ton of mining drainage was about 0.55 RMB, which could bring about considerable economic benefit for coal mining enterprises.
Influence of micelle properties on micellar-enhanced ultrafiltration for chromium recovery
Authors: Nguyen Hau Thi , Chang Wen-Shing , Nguyen Nguyen Cong , Chen Shiao-Shing , Chang Hau-Ming
Published: December 2015

An investigation of micelle properties on the recovery of chromium for micellar enhanced ultrafiltration (MEUF) process was conducted using cationic surfactant of cetyltrimethylammonium bromide (CTAB). The relationship between degree of ionization, micellar sizes and chromium removal were determined in this study. The results showed that the complete ionization for CTA+ and Br− was observed for CTAB lower than 0.72 mM and aggregation initiated at concentration of CTAB higher than 0.72 mM to yield attraction of counterion. The micellar sizes increased with increase in concentration of CTAB (higher than 4.02 mM) to generate micron-sized micelles. The distribution of micellar sizes was used to estimate the molecular weight cutoff of membrane used in the MEUF process. As chromium was added into aqueous CTAB solution, the chromate was dominant and bound on the micellar surface instead of Br−. Moreover, the presence of micelle formed a gel-layer to slightly shrink the membrane pore, therefore, UF membrane of 30k Da molecular weight cutoff (pore size ≈ 7.9 nm) was selected in the MEUF process to achieve the removal efficiency of Cr(VI) higher than 95%.
Dissolved organic nitrogen (DON) during batch denitrification of low concentrations of nitrate using suspended and attached biomass
Authors: Brandão D. N. , Spanjers H. , van Lier J. B.
Published: December 2015

The occurrence and removal of dissolved organic nitrogen (DON) is an issue of increasing importance for the reclamation of treated wastewater. Effluent DON may act as a precursor of disinfection by-products during wastewater disinfection and may contribute to eutrophication of receiving surface waters. The aim of this study was to understand the effect of the post-denitrification process on final effluent DON (organic nitrogen filtered by 0.45 μm pore size) concentration to further gain knowledge on how to optimize denitrifying filtration, in order to reach the required discharge standards. To evaluate DON variation, denitrification batch experiments were carried out with suspended and attached biomass under different shear conditions. For both conditions, with suspended and attached biomass, DON concentration did not increase or decrease during the denitrification process with addition of an external carbon source. Moreover, the increase of shear rate did not affect the DON concentration. Apparently, there is no direct link between DON evolution and the denitrification process itself.
Thermochemical pretreatment of lignocellulose residues: assessment of the effect on operational conditions and their interactions on the characteristics of leachable fraction
Authors: Vásquez Denisse , Contreras Elsa , Palma Carolyn , Carvajal Andrea
Published: December 2015

Annually, large amounts of agricultural residues are produced in Chile, which can be turned into a good opportunity to diversify the energy matrix. These residues have a slow hydrolysis stage during anaerobic digestion; therefore, the application of a pretreatment seems to be an alternative to improve the process. This work focused on applying a thermochemical pretreatment with NaOH on two lignocellulosic residues. The experiments were performed according to a 24 factorial design. The factors studied in a 24 factorial design were: temperature (60 and 120 °C), pretreatment time (10 and 30 minutes), NaOH dose (2 and 4%), and residue size (<1 and 1–3 mm for wheat straw; 1–5 and 5–10 mm for corn stover). The analyzed response variables were the solubilization of organic matter, and the biodegradability of the lignocellulose hydrolysate. The statistical analysis of the data allowed the identification of the experimental conditions that maximized solubilization of organic matter and biodegradability. The main results showed that more aggressive experimental conditions could increase the breaking down of the structure; in addition, the time of pretreatment was not significant. Conversely, the less aggressive experimental conditions, regarding regent dosage and downsizing, favored the release of biodegradable organic matter. The main conclusion of this study was the identification of the operational conditions of the thermochemical pretreatment that promote maximum biogas production, which was caused due to the solubilization of a large amount of organic matter, but not because of the increase in biodegradability of the released organic matter.
Evaluating the performance of water purification in a vegetated groundwater recharge basin maintained by short-term pulsed infiltration events
Authors: Mindl Birgit , Hofer Julia , Kellermann Claudia , Stichler Willibald , Teichmann Günter , Psenner Roland , Danielopol Dan L. , Neudorfer Wolfgang , Griebler Christian
Published: December 2015

Infiltration of surface water constitutes an important pillar in artificial groundwater recharge. However, insufficient transformation of organic carbon and nutrients, as well as clogging of sediments often cause major problems. The attenuation efficiency of dissolved organic carbon (DOC), nutrients and pathogens versus the risk of bioclogging for intermittent recharge were studied in an infiltration basin covered with different kinds of macrovegetation. The quality and concentration of organic carbon, major nutrients, as well as bacterial biomass, activity and diversity in the surface water, the porewater, and the sediment matrix were monitored over one recharge period. Additionally, the numbers of viral particles and Escherichia coli were assessed. Our study showed a fast establishment of high microbial activity. DOC and nutrients have sustainably been reduced within 1.2 m of sediment passage. Numbers of E. coli, which were high in the topmost centimetres of sediment porewater, dropped below the detection limit. Reed cover was found to be advantageous over bushes and trees, since it supported higher microbial activities along with a good infiltration and purification performance. Short-term infiltration periods of several days followed by a break of similar time were found suitable for providing high recharge rates, and good water purification without the risk of bioclogging.
Fouling and long-term durability of an integrated forward osmosis and membrane distillation system
Authors: Husnain T. , Mi B. , Riffat R.
Published: December 2015

An integrated forward osmosis (FO) and membrane distillation (MD) system has great potential for sustainable wastewater reuse. However, the fouling and long-term durability of the system remains largely unknown. This study investigates the fouling behaviour and efficiency of cleaning procedures of FO and MD membranes used for treating domestic wastewater. Results showed that a significant decline in flux of both FO and MD membranes were observed during treatment of wastewater with organic foulants. However, shear force generated by the increased cross-flow physically removed the loosely attached foulants from the FO membrane surface and resulted in 86–88% recovery of flux by cleaning with tap water. For the MD membrane, almost no flux recovery was achieved due to adsorption of organic foulants on the hydrophobic membrane surface, thus indicating significant irreversible fouling/wetting, which may not be effectively cleaned even with chemical reagents. Long-term (10 d) tests showed consistent performance of the FO membrane by rejecting the contaminants. However, organic foulants reduced the hydrophobicity of the MD membrane, caused wetting problems and allowed contaminants to pass through. The results demonstrate that combination of the FO and MD processes can effectively reduce irreversible membrane fouling and solve the wetting problem of the MD membrane.
Recovery of Cu(II) by chemical reduction using sodium dithionite: effect of pH and ligands
Authors: Chou Yi-Hsuan , Yu Jui-Hsuan , Liang Yang-Min , Wang Pin-Jan , Li Chi-Wang , Chen Shiao-Shing
Published: December 2015

Wastewaters containing Cu(II) and ligands are ubiquitous in various industrial sectors, and efficacy of copper removal processes, especially precipitation, is greatly compromised by ligands. Chemical reduction, being commonly employed for production of metal nanoparticles, is also effective for metal removal. Adjustment of pH and addition of ligands are important to control the particle size in metallic nanoparticle production. Exploiting the fact that ligands and metals coexist in many wastewaters, chemical reduction was employed to treat ligand-containing wastewater in this study. The experimental result shows that depending on pH, type of ligands, and copper:ligand molar ratio, copper could be removed by either the reduction or precipitation mechanism. Almost complete copper removal could be achieved by the reduction mechanism under optimal condition for solutions containing either EDTA (ethylenediaminetetraacetic acid) or citrate ligands. For solutions containing ammonia, depending on pH and Cu:ammonia molar ratio, copper was removed by both precipitation and reduction mechanisms. At pH of 9.0, formation of nano-sized particles, which readily pass through a 0.45 μm filter used for sample pretreatment before residual copper analysis, results in the lowest copper removal efficiency. Both cuprous oxide and metallic copper are identified in the solids produced, and the possible explanations are provided.
Enhanced removal of nitrate from water using nZVI@MWCNTs composite: synthesis, kinetics and mechanism of reduction
Authors: Babaei Ali Akbar , Azari Ali , Kalantary Roshanak Rezaei , Kakavandi Babak
Published: December 2015

Herein, multi-wall carbon nanotubes (MWCNTs) were used as the carrier of nano-zero valent iron (nZVI) particles to fabricate a composite known as nZVI@MWCNTs. The composite was then characterized and applied in the nitrate removal process in a batch system under anoxic conditions. The influential parameters such as pH, various concentrations of nitrate and composite were investigated within 240 min of the reaction. The mechanism, kinetics and end-products of nitrate reduction were also evaluated. Results revealed that the removal nitrate percentage for nZVI@MWCNTs composite was higher than that of nZVI and MWCNTs alone. Experimental data from nitrate reduction were fitted to the Langmuir–Hinshelwood kinetic model. The values of observed rate constant (kobs) decreased with increasing the initial concentration of nitrate. Our experiments proved that the nitrate removal efficiency was favorable once both high amounts of nZVI@MWCNTs and low concentrations of nitrate were applied. The predominant end-products of the nitrate reduction were ammonium (84%) and nitrogen gas (15%). Our findings also revealed that ZVI@MWCNTs is potentially a good composite for removal/reduction of nitrate from aqueous solutions.
The role of a hybrid phytosystem in landscape water purification and herbicides removal
Authors: Kirumba George , Ge Ling , Wei Dongyang , Xu Cong , He Yiliang , Zhang Bo , Jiang Cheng , Mao Feijian
Published: December 2015

The performance of a hybrid phytosystem in landscape water purification and herbicides removal was investigated. The phytosystem operating in an arboretum is located in the Minhang Campus of Shanghai Jiao Tong University, China. The phytosystem is composed of two purification stages: sedimentation Stage 1 without external air supply; and Stage 2 with an external air supply. Stage 2 is also vegetated with three major kinds of plants, namely Pontederia cordata L., Typha latifolia L. and Cyperus alternifolius L. The system's hydraulic loading rate (HLR) was maintained at 1.632 m/day between December 2013 and November 2014. Sedimentation, filtration and adsorption by filter media, combined microbial processes in the rhizosphere (nitrification–denitrification) and plant uptake of the pollutants were all responsible for water purification in the phytosystem. The biological and physical parameters analyzed were total dissolved nitrogen (TDN), nitrate (NO3-N), nitrite (NO2-N), ammonia (NH3-N), total dissolved phosphorus (TDP), dissolved organic carbon (DOC), turbidity, chlorophyll-a and algal cells number. Highest removal efficiencies for TDN, TDP, turbidity, DOC, chlorophyll-a and algal cells were 56.9%, 73.3%, 92.4%, 29.9%, 94.3% and 91.0%, respectively. When the phytosystem was considered for herbicides removal, removal efficiencies of more than 25% were noted for all the herbicides.
Effects of thermal hydrolysis temperature on physical characteristics of municipal sludge
Authors: Feng Guohong , Guo Yabing , Tan Wei
Published: December 2015

Effects of thermal hydrolysis temperature on the physical properties of municipal sludge was further studied by a series of experiments. There was a decrease in bound water content with an increase in hydrolysis temperature, while there was an increase in pH at temperatures below 120 °C, and a decrease at temperatures exceeding 120 °C. An analysis of settleability, centrifugation and vacuum filtration of the treated sludge indicated that the threshold temperature was 120 °C, which was the same as the temperature for the bound water content and particle size. In addition, raw sludge with a solids content of 100 g/L, exhibited significant non-Newtonian fluid characteristics. At thermal hydrolysis temperatures exceeding 120 °C, non-Newtonian fluid characteristics including liquid and solid characteristics were significantly weakened. The consistency index (k) decreased from 5.90 Pa·s to 0.068 Pa·s, while the flow index (n) increased from 0.31 to 0.74, suggesting that thermal hydrolysis sludge was much closer to Newtonian fluids compared to raw sludge. Modification of bound water content, particle size and viscosity with hydrolysis temperature, revealed the nature of improved dewaterability by thermal hydrolysis. The fractal dimension of the sludge floc increased from 2.74 to 2.90, meaning that the floc became more compact after thermal hydrolysis.
Adsorption experiment of toxic micro-pollutants derived from automobiles using red soil
Authors: Kawai Takahiro , Ichiki Atsushi , Sawada Yasunori
Published: December 2015

In some countries, non-point source pollution derived from a city's economic activities tends to be a barrier to the improvement of water quality. Roadway runoff is known to contain toxic micro-pollutants such as polycyclic aromatic hydrocarbons (PAHs). Conversely, red soil is known to adsorb some organic matter. In this study, artificial roadway runoff water containing toxic micro-pollutants was made using roadway dust collected from a highway, and used for both batch-type tests and soil column tests with red soil in order to understand adsorption ability of the red soil on such toxic micro-pollutants, especially PAHs. In the batch-type tests, PAHs could be removed by approximately 40% when the contact time was 90 minutes. In the soil column tests, PAHs were removed by more than 80% while suspended solids were removed by more than 90%. Notably, PAHs with a high molecular weight were removed more readily in the tests than PAHs with a low molecular weight.
Charicterization and investigation of heat transfer enhancement in pool boiling with water-ZnO nanofluid
Authors: Kshirsagar Jagdeep , Shrivastava Ramakant , Adwani Prakash
Published: December 2015

The main focus of the present work is to characterize the ZnO nanoparticles further to prepare the ZnO nanofluid with base fluid as deionised water and to investigate enhancement in critical heat flux at different weight concentrations of nanofluids. The size of nanoparticles is found to be 55.25 nm. To study critical heat flux enhancement using ZnO nanofluid, different weight concentration of nanofluid are prepared. It is observed that maximum enhancement is 47.16% for 1.5 wt.% of ZnO nanofluid. Surface roughness and scanning electron microscopy of heater surface is carried out for all weight concentrations of nanofluid, which shows increase in Ra value up to some extent then it decreases and porosity on the surface of heater observed in scanning electron microscopy, is the source to enhance critical heat flux.
Characterization and statistical modelling of thermal resistance of cotton/polyester blended double layer interlock knitted fabrics
Authors: Afzal Ali , Ahmad Sheraz , Rasheed Abher , Mohsin Muhammad , Ahmad Faheem , Nawab Yasir
Published: December 2015

The aim of this study was to analyse and model the effect of knitting parameters on the thermal resistance of cotton/polyester double layer interlock knitted fabrics. Fabric samples of areal densities ranging from 310-495 g/m2 were knitted using yarns of three different cotton/polyester blends, each of two different linear densities by systematically varying knitting loop lengths for achieving different cover factors. It was found that by changing the polyester content in the inner and outer fabric layer from 40 to 65% in the double layer knitted fabric has statistically significant effect on the fabric thermal resistance. Fabric thermal resistance increased with increase in relative specific heat of outer fabric layer, yarn linear density, loop length, and fabric thickness while decrease in fabric areal density. It was concluded that response surface regression modelling could be successfully used for the prediction of thermal resistance of double layer interlock knitted fabrics. The model was validated by unseen data set and it was found that the actual and predicted values were in good agreement with each other with less than 10% absolute error. Sensitivity analysis was also performed to find out the relative contribution of each input parameter on the air permeability of the double layer interlock knitted fabrics.
Experimental and simulation testing of thermal loading in the jet tabs of a thrust vector control system
Authors: Zivkovic Sasa , Milinovic Momcilo , Stefanovic Predrag , Pavlovic Pavle , Gligorijevic Nikola
Published: December 2015

The paper discusses the temperature changes in mechanical jet tabs in a
system of rocket motor thrust vector control, estimated by the simulation and
experimental tests methodology. The heat transfer calculation is based on
complex computational fluid dynamics simulations of both the nozzle and
external tab flows, as the comprehensive integral flow zones with high flow
parameters gradients. Due to a complexity of the model for flow calculations,
the experimental estimation of the calculated results is carried out. The
temperature is measured by jet tabs embedded thermocouples, and conducted
through the rocket motor static tests. A good agreement of the calculated and
measured results is achieved. The main aim of the developed method is to
establish an approved calculation tool for designing new TVC systems in order
to avoid disadvantages due to overheating.
Modeling and identification of heat exchanger process using least squares support vector machines
Authors: Al-Dhaifallah Mujahed , Nisar Kottakkaran , Agarwal Praveen , Elsayyad Alaa
Published: December 2015

In this paper, Hammerstein model and non-linear autoregressive with eXogeneous inputs (NARX) model are used to represent tubular heat exchanger. Both models have been identified using least squares support vector machines based algorithms. Both algorithms were able to model the heat exchanger system with-out requiring any a priori assumptions regarding its structure. The results indicate that the blackbox NARX model outperforms the NARX Hammerstein model in terms of accuracy and precision.
The characteristics of combustion process of diesel engine using vegetable oil methyl esters
Authors: Knezevic Dragan , Tomic Miroljub , Stajic Vlada , Petrovic Velimir , Bulatovic Zeljko
Published: December 2015

Biodiesel is one of the promising renewable, alternative and environmentally
friendly biofuels that can be used in diesel engine with little or no
modification in the engine. The present paper investigates the combustion
characteristics of single cylinder, naturally aspirated, air cooled, DI
diesel engine fuelled with pure (100%) methyl ester of rapeseed oil (RME),
comparing to the corresponding characteristics when it was driven by diesel
fuel. Combustion process analysis was done on relatively low load level that
corresponds to the mean effective pressure of three bars and at constant
engine speed for both fuels. It was also concluded that the test engine can
operate without problems, both with that fuel and with a lot of other
biofuels and their mixtures that were used during long laboratory research.
Evaluation of Bond Strength and Microleakage of a Novel Metal-titanate Antibacterial Agent
Authors: Deng S , Chung KH , Chan DCN , Spiekerman C
Published: December 2015

Objectives: To evaluate the effect on both bond strength and microleakage of incorporation of a novel antibacterial nanoparticulate metal-titanate complex (nMT) into a dental adhesive system.

Materials and Methods: Eighty extracted human molars were prepared to determine whether incorporation of nMT into bonding agents can affect shear bond strength (SBS) and adhesive strength fatigue. SBS was measured with a universal testing machine, and the peak force at failure was recorded. An electromechanical fatigue machine was used for cyclic loading treatment of specimens. Differences in the SBS values among groups were identified using analysis of variance and Tukey post hoc analyses (α=0.05). Twenty standard Class V cavities were restored to examine microleakage when the primer/bonding resin was modified with 10 wt% nMT. Microleakage at the enamel and dentin margins was calculated as a percentage of the full length of the cavity. Results of the microleakage experiment were analyzed with paired and independent sample t-tests (α=0.05).

Results: The mean (± standard deviation) shear bond strength values of before fatigue and after fatigue ranged from 21.9 (2.5) MPa to 23.9 (3.8) MPa and from 17.1 (2.5) MPa to 17.7 (2.5) MPa respectively. No statistically significant differences in failure force were observed among groups (p=0.70). Microleakage under all conditions was significantly greater in the dentin margins than in the enamel margins (p<0.05). There was no evidence that microleakage differed between the experimental groups with modified primer and bonding resin.

Conclusions: Incorporating nMT into a dental adhesive system will not compromise the resin composite's tooth bonding and sealing ability.
Ceramic Veneers and Direct-Composite Cases of Amelogenesis Imperfecta Rehabilitation
Authors: Shibata S , Taguchi CMC , Gondo R , Stolf SC , Baratieri LN
Published: December 2015

The aim of this article is to present two case reports for the treatment of patients affected with amelogenesis imperfecta. One case was treated with composite resin and the other case with ceramic veneers. Esthetic and functional results were achieved using both treatments, and a review of advantages and disadvantages is presented.
Supervisors' Transformational Leadership and Bullying in the Workplace
Authors: Dussault Marc , Frenette Éric
Published: December 2015

The study tests the relationship between supervisors' transformational, transactional, and laissez-faire leadership and perceived bullying in the workplace. Transformational and transactional leaders can create conditions that make bullying at work less frequent but laissez-faire leadership may cause conflict that can result in bullying. The participants were 288 adults (122 women, 164 men; M age = 38.9 yr., SD = 11.7; M tenure = 7.2 yr.) employed across several organizations. Of the participants, 53.2% were contacted during an evening class in organizational behavior, and the others were workers from a waterproofing company. Scales measuring perceived leadership of a supervisor and perceived bullying at work were administered. Supervisor's transformational and transactional leadership were negatively related to work-related bullying, person-related bullying, and physically intimidating bullying. Transactional leadership was also negatively related to Work-related bullying, perceived Person-related bullying, and perceived Physically intimidating bullying. Supervisor's laissez-faire leadership was positively related to Work-related bullying, perceived Person-related bullying, and perceived Physically intimidating bullying. The use of Bass's model of transformational leadership in relation with the three-factor structure of the Negative Acts Questionnaire–Revised is unique in research on leadership and bullying. The relationship between laissez-faire leadership and leadership support results from previous studies: transactional or transformational leadership is likely to provide an environment that makes bullying more rare than under a negative or passive leadership.
The Relationship between Mental Toughness, Stress, and Burnout among Adolescents: A Longitudinal Study with Swiss Vocational Students
Authors: Gerber Markus , Feldmeth Anne Karina , Lang Christin , Brand Serge , Elliot Catherine , Holsboer-Trachsler Edith , Pühse Uwe
Published: December 2015

Past research has shown that higher stress is associated with increased burnout symptoms. The purpose of this study was to test whether mental toughness protects against symptoms of burnout and whether mental toughness moderates the relationship between perceived stress and burnout over time. Fifty-four vocational students ( M age = 18.1 yr., SD = 1.2; 27 males, 27 females) completed self-report questionnaires twice, 10 mo. apart. Perceived stress, mental toughness, and burnout were measured using the Adolescent Stress Questionnaire (ASQ), the Mental Toughness Questionnaire (MTQ), and the Shirom-Melamed Burnout Measure (SMBM). Students who perceived higher stress and lower mental toughness scores reported higher burnout symptoms. Although no significant interaction effects were found between stress and mental toughness in the prediction of burnout, the graphical inspection of the interactions indicated that among students with high stress, those with high mental toughness remained below the cutoff for mild burnout, whereas an increase in burnout symptoms was observable among peers with low mental toughness.
An emotional journey of identity change and transformation: The impact of study-abroad experience on the lives and careers of Chinese students and returnees
Authors: Gu Qing
Published: December 2015

This article discusses the nature of Chinese students' transnational experiences and its impact on their identities within and beyond national and cultural boundaries. The discussion is located in the theoretical framework of transnationalism and explores in detail the ways in which students adapt, change and develop, both in the host country of their study and also on their return to work in their home countries. Empirical evidence in the article is drawn from the findings of three studies, led by the author, which have investigated the pedagogical, sociocultural and emotional challenges that Chinese students have encountered when studying at British universities, and the perceived impact of their overseas studies on their lives and careers in their home countries. The research findings suggest that there are distinctive patterns of challenges, struggles, adjustments, change and achievement over time – all of which are embedded in the processes of socialisation, enculturation and professionalisation. Such experiences are both transitional and transformational and, most profoundly, they necessitate identity change at and across different layers of boundaries. At the heart of this identity change is a constant, emotional search for a reflexive sense of self as an embodied individual, a member of a professional group and a member of an organisation.
Prevalence and type of cervical deformities among adults with Parkinson's disease: a cross-sectional study
Authors: Moon Bong Ju , Smith Justin S. , Ames Christopher P. , Shaffrey Christopher I. , Lafage Virginie , Schwab Frank , Matsumoto Morio , Baik Jong Sam , Ha Yoon
Published: December 2015

OBJECT

To identify the characteristics of cervical deformities in Parkinson's disease (PD) and the role of severity of PD in the development of cervical spine deformities, the authors investigated the prevalence of the cervical deformities, cervical kyphosis (CK), and cervical positive sagittal malalignment (CPSM) in patients with PD. They also analyzed the association of severity of cervical deformities with the stage of PD in the context of global sagittal spinopelvic alignment.

METHODS

This study was a prospective assessment of consecutively treated patients (n = 89) with PD. A control group of the age- and sex-matched patients was selected from patients with degenerative cervical spine disease but without PD. Clinical and demographic parameters including age, sex, duration of PD, and Hoehn and Yahr (H&Y) stage were collected. Full-length standing radiographs were used to assess spinopelvic parameters. CK was defined as a C2–7 Cobb angle < 0°. CPSM was defined as C2–7 sagittal vertical axis (SVA) > 4 cm.

RESULTS

A significantly higher prevalence of CPSM (28% vs 1.1%, p < 0.001), but not CK (12% vs 10.1%, p = 0.635), was found in PD patients compared with control patients. Among patients with PD, those with CK were younger (62.1 vs 69.0 years, p = 0.013) and had longer duration of PD (56.4 vs 36.2 months, p = 0.034), but the severity of PD was not significantly different. Logistic regression analysis revealed that the presence of CK was associated with younger age, higher mismatch between pelvic incidence and lumbar lordosis, and lower C7–S1 SVA. The patients with CPSM had significantly greater thoracic kyphosis (TK) (p < 0.001) and a trend toward more advanced H&Y stage (p = 0.05). Logistic regression analysis revealed that CPSM was associated with male sex, greater TK, and more advanced H&Y stage.

CONCLUSIONS

Patients with PD have a significantly higher prevalence of CPSM compared with age- and sex-matched control patients with cervical degenerative disease but without PD. Among patients with PD, CK is not associated with the severity of PD but is associated with overall global sagittal malalignment. In contrast, the presence of CPSM is associated more with the severity of PD than it is with the presence of global sagittal malalignment. Collectively, these data suggest that the neuromuscular pathogenesis of PD may affect the development of CPSM more than of CK.
Preoperative retrolisthesis as a risk factor of postdecompression lumbar disc herniation
Authors: Takenaka Shota , Tateishi Kosuke , Hosono Noboru , Mukai Yoshihiro , Fuji Takeshi
Published: December 2015

OBJECT

In this study, the authors aimed to identify specific risk factors for postdecompression lumbar disc herniation (PDLDH) in patients who have not undergone discectomy and/or fusion.

METHODS

Between 2007 and 2012, 493 patients with lumbar spinal stenosis underwent bilateral partial laminectomy without discectomy and/or fusion in a single hospital. Eighteen patients (herniation group [H group]: 15 men, 3 women; mean age 65.1 years) developed acute sciatica as a result of PDLDH within 2 years after surgery. Ninety patients who did not develop postoperative acute sciatica were selected as a control group (C group: 75 men, 15 women; mean age 65.4 years). Patients in the C group were age and sex matched with those in the H group. The patients in the groups were also matched for decompression level, number of decompression levels, and surgery date. The radiographic variables measured included percentage of slippage, intervertebral angle, range of motion, lumbar lordosis, disc height, facet angle, extent of facet removal, facet degeneration, disc degeneration, and vertebral endplate degeneration. The threshold for PDLDH risk factors was evaluated using a continuous numerical variable and receiver operating characteristic curve analysis. The area under the curve was used to determine the diagnostic performance, and values greater than 0.75 were considered to represent good performance.

RESULTS

Multivariate analysis revealed that preoperative retrolisthesis during extension was the sole significant independent risk factor for PDLDH. The area under the curve for preoperative retrolisthesis during extension was 0.849; the cutoff value was estimated to be a retrolisthesis of 7.2% during extension.

CONCLUSIONS

The authors observed that bilateral partial laminectomy, performed along with the removal of the posterior support ligament, may not be suitable for lumbar spinal stenosis patients with preoperative retrolisthesis greater than 7.2% during extension.
Utility of diffusion tensor imaging studies linked to neuronavigation and other modalities in repeat hemispherotomy for intractable epilepsy
Authors: Kiehna Erin N. , Widjaja Elysa , Holowka Stephanie , Carter Snead O. , Drake James , Weiss Shelly K. , Ochi Ayako , Thompson Eric M. , Go Cristina , Otsubo Hiroshi , Donner Elizabeth J. , Rutka James T.
Published: December 2015

OBJECT

Hemispherectomy for unilateral, medically refractory epilepsy is associated with excellent long-term seizure control. However, for patients with recurrent seizures following disconnection, workup and investigation can be challenging, and surgical options may be limited. Few studies have examined the role of repeat hemispherotomy in these patients. The authors hypothesized that residual fiber connections between the hemispheres could be the underlying cause of recurrent epilepsy in these patients. Diffusion tensor imaging (DTI) was used to test this hypothesis, and to target residual connections at reoperation using neuronavigation.

METHODS

The authors identified 8 patients with recurrent seizures following hemispherectomy who underwent surgery between 1995 and 2012. Prolonged video electroencephalography recordings documented persistent seizures arising from the affected hemisphere. In all patients, DTI demonstrated residual white matter association fibers connecting the hemispheres. A repeat craniotomy and neuronavigation-guided targeted disconnection of these residual fibers was performed. Engel class was used to determine outcome after surgery at a minimum of 2 years of follow-up.

RESULTS

Two patients underwent initial hemidecortication and 6 had periinsular hemispherotomy as their first procedures at a median age of 9.7 months. Initial pathologies included hemimegalencephaly (n = 4), multilobar cortical dysplasia (n = 3), and Rasmussen's encephalitis (n = 1). The mean duration of seizure freedom for the group after the initial procedure was 32.5 months (range 6–77 months). In all patients, DTI showed limited but definite residual connections between the 2 hemispheres, primarily across the rostrum/genu of the corpus callosum. The median age at reoperation was 6.8 years (range 1.3–14 years). The average time taken for reoperation was 3 hours (range 1.8–4.3 hours), with a mean blood loss of 150 ml (range 50–250 ml). One patient required a blood transfusion. Five patients are seizure free, and the remaining 3 patients are Engel Class II, with a minimum follow-up of 24 months for the group.

CONCLUSIONS

Repeat hemispherotomy is an option for consideration in patients with recurrent intractable epilepsy following failed surgery for catastrophic epilepsy. In conjunction with other modalities to establish seizure onset zones, advanced MRI and DTI sequences may be of value in identifying patients with residual connectivity between the affected and unaffected hemispheres. Targeted disconnection of these residual areas of connectivity using neuronavigation may result in improved seizure outcomes, with minimal and acceptable morbidity.
The role of obesity in the biomechanics and radiological changes of the spine: an in vitro study
Authors: Rodriguez-Martinez Nestor G. , Perez-Orribo Luis , Kalb Samuel , Reyes Phillip M. , Newcomb Anna G. U. S. , Hughes Jeremy , Theodore Nicholas , Crawford Neil R.
Published: December 2015

OBJECT

The effects of obesity on lumbar biomechanics are not fully understood. The aims of this study were to analyze the biomechanical differences between cadaveric L4–5 lumbar spine segments from a large group of nonobese (body mass index [BMI] < 30 kg/m2) and obese (BMI ≥ 30 kg/m2) donors and to determine if there were any radiological differences between spines from nonobese and obese donors using MR imaging.

METHODS

A total of 168 intact L4–5 spinal segments (87 males and 81 females) were tested using pure-moment loading, simulating flexion-extension, lateral bending, and axial rotation. Axial compression tests were performed on 38 of the specimens. Sex, age, and BMI were analyzed with biomechanical parameters using 1-way ANOVA, Pearson correlation, and multiple regression analyses. MR images were obtained in 12 specimens (8 from obese and 4 from nonobese donors) using a 3-T MR scanner.

RESULTS

The segments from the obese male group allowed significantly greater range of motion (ROM) than those from the nonobese male group during axial rotation (p = 0.018), while there was no difference between segments from obese and nonobese females (p = 0.687). There were no differences in ROM between spines from obese and nonobese donors during flexion-extension or lateral bending for either sex. In the nonobese population, the ROM during axial rotation was significantly greater for females than for males (p = 0.009). There was no significant difference between sexes in the obese population (p = 0.892). Axial compressive stiffness was significantly greater for the obese than the nonobese population for both the female-only group and the entire study group (p < 0.01); however, the difference was nonsignificant in the male population (p = 0.304). Correlation analysis confirmed a significant negative correlation between BMI and resistance to deformation during axial compression in the female group (R = −0.65, p = 0.004), with no relationship in the male group (R = 0.03, p = 0.9). There was also a significant negative correlation between ROM during flexion-extension and BMI for the female group (R = −0.38, p = 0.001), with no relationship for the male group (R = 0.06, p = 0.58). Qualitative analysis using MR imaging indicated greater facet degeneration and a greater incidence of disc herniations in the obese group than in the control group.

CONCLUSIONS

Based on flexibility and compression tests, lumbar spinal segments from obese versus nonobese donors seem to behave differently, biomechanically, during axial rotation and compression. The differences are more pronounced in women. MR imaging suggests that these differences may be due to greater facet degeneration and an increased amount of disc herniation in the spines from obese individuals.
Scoliosis may increase the risk of recurrence of lumbar disc herniation after microdiscectomy
Authors: Chang Hsuan-Kan , Chang Huang-Chou , Wu Jau-Ching , Tu Tsung-Hsi , Fay Li-Yu , Chang Peng-Yuan , Wu Ching-Lan , Huang Wen-Cheng , Cheng Henrich
Published: December 2015

OBJECT

The aim of this paper was to investigate the risk of recurrence of lumbar disc herniation (LDH) in patients with scoliosis who underwent microdiscectomy.

METHODS

A series of consecutive patients who underwent microdiscectomy for LDH was retrospectively reviewed. The inclusion criteria were young adults younger than 40 years who received microdiscectomy for symptomatic 1-level LDH. An exclusion criterion was any previous spinal surgery, including fusion or correction of scoliosis. The patients were divided into 2 groups: those with scoliosis and those without scoliosis. The demographic data in the 2 groups were similar. All medical records and clinical and radiological evaluations were reviewed.

RESULTS

A total of 58 patients who underwent 1-level microdiscectomy for LDH were analyzed. During the mean follow-up of 24.6 months, 6 patients (10.3%) experienced a recurrence of LDH with variable symptoms. The recurrence rate was significantly higher among the scoliosis group than the nonscoliosis group (33.3% vs 2.3%, p = 0.001). Furthermore, the recurrence-free interval in the scoliosis group was short.

CONCLUSIONS

Young adults (< 40 years) with uncorrected scoliosis are at higher risk of recurrent LDH after microdiscectomy.
The Death Penalty and Psychiatry: A Historical Overview
Authors: Gulrajani Chinmoy
Published: December 2015

Since its inception in the 17th century, capital punishment in the United States has undergone several drastic changes. In the past, physicians have been participants in several aspects of the death penalty and the issue of physician participation in this arena has always remained controversial. Psychiatrists form a unique group of physicians that, even though not a direct participant in the mechanics of the execution process itself, has been called upon to provide services in death penalty cases in ways that can influence the final verdict of life or death. This article provides a brief history of capital punishment in the United States and traces the landmark events over the years that have led to an expanded scope for psychiatrists' participation in death penalty cases.

[
Psychiatr Ann
. 2015;45(12):598–602.]