bluuebunny/crossref_metadata_2025 huggingface dataset:
Tolerance to hydraulic and organic load fluctuations in constructed wetlands
Authors: Masi F. , Martinuzzi N. , Bresciani R. , Giovannelli L. , Conte G.
Published: July 2007

This paper describes a two-year performance evaluation of four different constructed wetland (CW) treatment systems designed by IRIDRA Srl, located in central Italy. All four CW systems were established to treat wastewater effluent from different tourist activities: (1) one single-stage CW for secondary treatment of domestic wastewater (30 p.e.) at a holiday farm site; (2) a hybrid compact system consisting of two stages, a horizontal flow (HF) system followed by a vertical flow (VF) system for the secondary treatment of effluent from a 140 p.e. tourist resort; (3) a single-stage vertical flow (VF) CW for a 100 p.e. mountain shelter; and (4) a pair of single-stage, HF CWs for the secondary treatment of segregated grey and black water produced by an 80 p.e. camping site. These tourism facilities are located in remote areas and share some common characteristics concerning their water management: they have high variability of water consumption and wastewater flow, depending on the season, weather and weekly regularities; they have no connection to a public sewer and most sites are located in a sensitive environment.

Total suspended solids (TSS), chemical oxygen demand (COD), biochemical oxygen demand (BOD5), ammonium (N-NH+4), nitrate (N-NOx), total nitrogen (Ntot), total phosphorus (Ptot), total coliform (TC), faecal coliform (FC), E. coli removal efficiencies for all four CW systems are presented. The results from this study demonstrate the potential of CWs as a suitable technology for treating wastewater from tourism facilities in remote areas. A very efficient COD reduction (83–95%) and pathogen elimination (3–5 logs) have been achieved. Furthermore, the CWs are easily maintained, robust (not sensitive to peak flows), constructed with local materials, and operate with relatively low cost.
Effects of sorption, sulphate reduction, and Phragmites australis on the removal of heavy metals in subsurface flow constructed wetland microcosms
Authors: Lesage E. , Rousseau D.P.L. , Van de Moortel A. , Tack F.M.G. , De Pauw N. , Verloo M.G.
Published: July 2007

The removal of Co, Ni, Cu and Zn from synthetic industrial wastewater was studied in subsurface flow constructed wetland microcosms filled with gravel or a gravel/straw mixture. Half of the microcosms were planted with Phragmites australis and half were left unplanted. All microcosms received low-strength wastewater (1 mg L−1 of Co, Ni, and Zn, 0.5 mg L−1 Cu, 2,000 mg L−1 SO4) during seven 14-day incubation batches. The pore water was regularly monitored at two depths for heavy metals, sulphate, organic carbon and redox potential. Sorption properties of gravel and straw were assessed in a separate experiment. A second series of seven incubation batches with high-strength wastewater (10 mg L−1 of each metal, 2,000 mg L−1 SO4) was then applied to saturate the substrate. Glucose was added to the gravel microcosms together with the high-strength wastewater. Sorption processes were responsible for metal removal during start-up, with the highest removal efficiencies in the gravel microcosms. The lower initial efficiencies in the gravel/straw microcosms were presumably caused by the decomposition of straw. However, after establishment of anaerobic conditions (Eh∼−200 mV), precipitation as metal sulphides provided an additional removal pathway in the gravel/straw microcosms. The addition of glucose to gravel microcosms enhanced sulphate reduction and metal removal, although Phragmites australis negatively affected these processes in the top-layer of all microcosms.
Influence of macrophyte species on microbial density and activity in constructed wetlands
Authors: Gagnon V. , Chazarenc F. , Comeau Y. , Brisson J.
Published: July 2007

It is often assumed that planted wastewater treatment systems outperform unplanted ones, mainly because plants stimulate belowground microbial population. Yet, fundamental interactions between plants and associated microorganisms remain only partly understood. The aim of our project was to evaluate microbial density and activity associated to the rhizosphere of three plant species. Experimental set-up, in six replicates, consisted of four 1.8-L microcosms respectively planted in monoculture of Typha angustifolia, Phragmites australis, Phalaris arundinacea and unplanted control. Plants were grown for two months with 25 L m−2 d−1 of secondary effluent (in g m−2 d−1: 1.3 TSS, 7.5 COD, 1.0 TKN). Sampling of substrate, roots and interstitial water was made according to depth (0–10, 10–20 cm). Biofilm was extracted with 500 mL of a buffer solution. Microbial density was directly estimated by flow cytometry and indirectly by protein measurements. Biological activity was determined using respirometry assays, dehydrogenase and enzymatic activity measurements.

Our results show that microbial density and activity are higher in the presence of plants, with significantly higher values associated with Phalaris arundinacea. Greater density of aerobic or facultative bacteria was present in planted microcosm, particularly on root surface, suggesting root oxygen release. Microbes were present on substrate and roots as an attached biofilm and abundance was correlated to root surface throughout depth. Plant species root morphology and development seem to be a key factor influencing microbial–plant interaction.
On fitting the k-C* first order model to batch loaded sub-surface treatment wetlands
Authors: Stein O.R. , Towler B.W. , Hook P.B. , Biederman J.A.
Published: July 2007

The k-C* first order model was fit to time-series COD data collected from batch-loaded model wetlands. Four replicates of four plant species treatments; Carex utriculata (sedge), Schoenoplectus acutus (bulrush), Typha latifolia (cattail) and unplanted controls were compared. Temperature was varied by 4 °C from 24 °C to 4 °C to 24 °C over a year-long period. One mathematical fit was made for each wetland replicate at each temperature setting (192 fits). Temperature effects on both parameters were subsequently estimated by fitting the Arrhenius relationship to the estimated coefficients. Inherent interactions between k and C* make values dependent on sample timing and statistical technique for either time series (batch load) or distance profile (plug flow) data. Coefficients calibrated using the Levenberg–Marquardt method are compared to values previously reported using a nonlinear mixed effect regression technique. Overall conclusions are similar across approaches: (a) the magnitude of the coefficients varies strongly by species; (b) the rate constant k decreases with increasing temperature; and (c) temperature and species variation in the residual concentration C* is greater than the variation in k, such that variation in k alone is a poor predictor of performance. However, the magnitudes of the coefficients, especially the rate parameter k, vary between the statistical techniques, highlighting the need to better document the statistical routines used to calibrate the k-C* model.
Evaluation of constructed wetlands by wastewater purification ability and greenhouse gas emissions
Authors: Gui P. , Inamori R. , Matsumura M. , Inamori Y.
Published: July 2007

Domestic wastewater is a significant source of nitrogen and phosphorus, which cause lake eutrophication. Among the wastewater treatment technologies, constructed wetlands are a promising low-cost means of treating point and diffuse sources of domestic wastewater in rural areas. However, the sustainable operation of constructed wetland treatment systems depends upon a high rate conversion of organic and nitrogenous loading into their metabolic gaseous end products, such as N2O and CH4. In this study, we examined and compared the performance of three typical types of constructed wetlands: Free Water Surface (FWS), Subsurface Flow (SF) and Vertical Flow (VF) wetlands. Pollutant removal efficiency and N2O and CH4 emissions were assessed as measures of performance. We found that the pollutant removal rates and gas emissions measured in the wetlands exhibited clear seasonal changes, and these changes were closely associated with plant growth. VF wetlands exhibited stable removal of organic pollutants and NH3-N throughout the experiment regardless of season and showed great potential for CH4 adsorption. SF wetlands showed preferable T-N removal performance and a lower risk of greenhouse gas emissions than FWS wetlands. Soil oxidation reduction potential (ORP) analysis revealed that water flow structure and plant growth influenced constructed wetland oxygen transfer, and these variations resulted in seasonal changes of ORP distribution inside wetlands that were accompanied by fluctuations in pollutant removal and greenhouse gas emissions.
Biodegradation of chlorobenzene in a constructed wetland treating contaminated groundwater
Authors: Braeckevelt M. , Rokadia H. , Mirschel G. , Weber S. , Imfeld G. , Stelzer N. , Kuschk P. , Kästner M. , Richnow H.H.
Published: July 2007

Monochlorobenzene (MCB) is an important groundwater contaminant world-wide. In this study, a horizontal subsurface flow constructed wetland with an integrated water compartment was fed with MCB contaminated groundwater originating from the local aquifer. Analysis of spatial concentration dynamics of MCB and oxygen was combined with isotope composition analysis of MCB for assessing in situ biodegradation. Removal of MCB was most effective in the upper layer of the soil filter, reaching up to 77.1%. Trace oxygen concentrations below 0.16 mg L−1 were observed throughout the wetland transect, suggesting a considerable limitation of aerobic microbial MCB degradation. Enrichment of 13C in the residual MCB fraction at increasing distance from the inflow point indicated microbial MCB degradation in the wetland. The observed isotope shift was higher than expected for aerobic MCB degradation and thus pointed out a significant contribution of an anaerobic degradation pathway to the overall biodegradation.
Application of culture-independent methods to assess the bacteria removal efficiency of subsurface flow constructed wetlands
Authors: Alexandrino M. , Grohmann E. , Szewzyk R. , Szewzyk U.
Published: July 2007

The bacteriologic treatment efficiency of vertical and horizontal subsurface flow constructed wetlands (SFCWs) was analysed in two multistage wastewater treatment systems by culture dependent and independent methods. When assessed with standard cultivation procedures, bacteria removal efficiency of the vertical and horizontal SFCWs was similar. However, microscopic enumerations of the wastewater bacteria after DNA staining revealed a completely different removal pattern: bacteria removal efficiency of the horizontal SFCWs was in general low and erratic, whereas the vertical SFCWs displayed high bacteria removal rates. The discrepancies in the results obtained by bacteria enumeration and cultivation was due to a strong decrease in bacterial culturability after treatment by the horizontal SFCWs, leading to overestimation of the real bacterial concentrations in these effluents. Additionally, a PCR based approach for the detection of the enteropathogenic bacteria Campylobacter jejuni and Yersinia enterocolitica was tested in the wastewater samples. The methods were specific and reproducible in the analysed samples and could be carried out within 12 h, proving very adequate as an alternative to cultivation. This work recommends a review of the current standard methodology for wastewater quality surveillance, as well as of the design of SFCW.
Phragmites australis peroxidases role in the degradation of an azo dye
Authors: Carias C.C. , Novais J.M. , Martins-Dias S.
Published: July 2007

Phragmites australis are commonly used in constructed wetlands either for domestic sewage or industrial effluents treatment. The aerobic mineralization mechanisms of Acid Orange 7, AO7, in a Vertical Flow Constructed Wetland (VFCW) planted with P. australis suggest that AO7 degradation pathway may involve enzymes like peroxidases (POD), known to degrade some recalcitrant pollutants. In this context, the aim of this study was to evaluate the role of POD extracted from the VFCW P. australis leaves in the decolourization of AO7, which belongs to the very restricted group of bio-degradable azo dyes and is widely used in the textile industry. Leaves' crude extract (CE) was purified by protein fractioning with ammonium sulphate (20–80%). AO7 (0.14 mM) decolourization rate of each CE fraction was determined using hydrogen peroxide (0.2 mM) as a co-substrate. A maximum specific activity of 6.8 × 10−3 μmol QNNM min−1 mg protein−1 was obtained for the 40–60% fraction. The results obtained suggest that P. australis may be a good candidate for the treatment of AO7 contaminated effluents in a VFCW, as very high removal efficiencies were achieved at pilot scale and in vitro studies leading to the decolourization of the dye, suggesting a positive and active role of P. australis in the removal mechanisms within the VFCW. Moreover, some questions were put forward regarding the participation of other important plant enzymes in the degradation process.
The root surface as the definitive detail for microbial transformation processes in constructed wetlands – a biofilm characteristic
Authors: Münch Ch. , Neu T. , Kuschk P. , Röske I.
Published: July 2007

It was the goal of the investigations to characterise the biofilm on the plant roots because of the demonstrable major role of these associated bacteria. The essential criteria for the research were to look at the structure of the microbial colonisation (pattern, density) and to determine properties of the rhizoplane biofilm such as thickness and structure.

The root material from a hydroponic system, planted with Glyceria maxima and used for nitrogen removal, has been used for the investigations. Several properties of the bacteria became visible due to the application of specific dyes. The evaluation of the samples was performed by scanning confocal laser microscopy (CLSM).

It was shown that the microbial colonisation of the root surface of Glyceria maxima was on an unexpected high level and seems to be related mainly to the permeability and therefore to the age of the plant roots. The thickness of the rhizoplane biofilm is remarkably thin; no inactive layers could be observed in contrast to biofilm growing on technical carrier material. Caused by the untypically two-sided supply with nutrients the whole biofilm is in interaction with the surroundings. This indicates the importance of the plant roots for the microbial transformation processes in wetlands and underlines the especialness of the root as carrier for microorganisms.
Effects of Dry Ice and Superchilling on Quality and Shelf Life of Arctic Charr (Salvelinus alpinus) Fillets
Authors: Bao Huynh Nguyen Duy , Arason Sigurjón , Þórarinsdóttir Kristín Anna
Published: July 2007

The influence of different cooling techniques (dry ice/ice packs) and storage temperature (-2°C/3°C) to prolong the shelf life of Arctic charr (Salvelinus alpinus) fillets were evaluated by sensory analysis, physical methods, chemical and microbial analysis. The effects of storage temperature were stronger than of different cooling agents. Superchilling (-2°C) of fillets packed with dry ice resulted in 6 days extension of shelf life compared to chilling (3°C). The use of dry ice parallel to superchilling prolonged shelf life for 1 day compared to fillets stored with ice packs. No negative effects on quality of the fillets where detected that could be linked to cell destruction caused by partial freezing or to sour taste, caused by absorption of CO2 gas in fish flesh.
Measurements of the Crystallization Rates of Amorphous Sucrose and Lactose Powders from Spray Drying
Authors: Wang Shuosi , Langrish Tim
Published: July 2007

The effects of temperature, relative humidity and molecular structure on the crystallization process within amorphous solids have been explored. Lactose and sucrose were spray dried, and the products were exposed to different and relative humidities. To investigate the effect of temperature, experiments were conducted at both room temperature and 40oC. The rate of the crystallization was more than doubled for every increase of temperature by 10oC, up to three times for the case of lactose. These results are consistent with the picture of the process as an activated rate one. The effect of increasing relative humidity (RH) was observed to increase the rate of crystallization up to a threshold value, after which the rate was no longer affected by relative humidity. This threshold was found to be 51% for sucrose, at room temperature, which was lowered to 32% at 40oC. Lactose and sucrose, which have the same molecular weight of 342 g/mol but different molecular structures and thus glass transition temperatures, were exposed to similar conditions. The difference in molecular structures had little effect on the overall rate of the crystallization process for the same material temperatures, in contrast with the predictions of the Williams Landel Ferry equation, which suggests that the rate of crystallization is a function of the difference between the material temperature and the glass transition temperature.
Substitution, Spending Offsets, and Prescription Drug Benefit Design
Authors: Gaynor Martin , Li Jian , Vogt William B
Published: July 2007

Many U.S. employers have recently adopted less generous prescription drug benefits. In addition, in 2006 the U.S. began to offer prescription drug insurance to approximately 42 million Medicare beneficiaries. We used data on individual health insurance claims and benefit data from 1997 to 2003 to study how changes in consumers co-payments for prescription drugs affect use of and expenditure on prescription drugs, inpatient care, and outpatient care. We analyzed the effects both in the year of the co-payment change and in the year following the change. Our results show that increases in prescription drug prices reduce both use of and spending on prescription drugs. They also show that consumers substitute the use of outpatient care for prescription drug use and that about 35% of the expenditure reductions on prescription drugs are offset by increases in other spending.
Life Is Cheap: Using Mortality Bonds to Hedge Aggregate Mortality Risk
Authors: Friedberg Leora , Webb Anthony
Published: July 2007

Insurance companies, employer pension plans, and the U.S. government all provide annuities and therefore assume aggregate mortality risk. Using the widely-cited Lee-Carter mortality model, we quantify aggregate mortality risk as the risk that the average annuitant lives longer than is predicted by the model, and we determine that annuities expose providers to substantial risk. We also find that other recent actuarial forecasts lie at the edge or outside of Lee-Carter's 95% confidence interval, suggesting even more uncertainty about future mortality.We then evaluate the implications of aggregate mortality risk for insurance companies; this analysis can be extended to private pension providers and Social Security. Given the forecasts of the Lee-Carter model, we calculate that a markup of 3.9% on an annuity premium (or shareholders' capital equal to 3.9% of the expected present value of annuity payments) would be required to reduce the probability of insolvency resulting from aggregate mortality shocks to 5%, and a markup of 5.7% would reduce the probability of insolvency to 1%. Based on the same model, we find that a projection scale commonly referred to by the insurance industry underestimates aggregate mortality improvements and would leave annuities underpriced.Annuity providers could manage aggregate mortality risk more efficiently by transferring it to financial markets through mortality-contingent bonds. We calculate the returns that one recently proposed mortality bond would have paid had it been available over a long period. Using both the Capital and the Consumption Capital Asset Pricing Models, we determine the risk premium that investors would have required to hold the bond. At plausible coefficients of risk aversion, annuity providers should be able to hedge aggregate mortality risk via such bonds at very low cost.
The Europeanisation of Education Policy: Researching Changing Governance and ‘New’ Modes of Coordination
Authors: Alexiadou Nafsika
Published: July 2007

This article explores how the European Union coordinates education policy making through the use of a mode of governance called the open method of coordination (OMC). Part One briefly presents and discusses the mechanisms of the education OMC and its key characteristics. Part Two draws on contemporary theories of Europeanisation and discourse analysis to provide a theoretical and methodological framework for researching the response of member states to this policy coordination. Member states of the European Union are not seen as passive recipients of policies from the European Commission and the Council of the European Union. Rather they engage in a complex process of selective adoption of policy measures that suit particular purposes, formulate various aspects of policy often in tension with other member states, and possibly reject those elements of policy that do not fit national priorities or timelines. Finally, the author briefly exemplifies these issues by operationalising key research questions around the issue of domestic response to the education OMC through a suggested research approach for the exploration of the process of Europeanisation of education policy.
Evaluation: Emergence, Mode of Inquiry, Theory and Practice
Authors: Kenny Aidan
Published: July 2007

The aim of this article is to present the reader with an accessible and practical account of evaluation as a mode of inquiry within the broad domain of social science. The starting point is the presentation of a general outline of the main milestones relating to the emergence of evaluation as a mode of inquiry and some of the prominent advocates of contemporary evaluation. Particular attention is directed towards what is termed as ‘programme evaluation’. Then the author endeavours to explore whether evaluation as a mode of inquiry is practice or theory led. A definitive answer to this question is not presented here in this short article; instead, the author makes assumptions based on his interpretation of the reviewed discourse within the field and personal reflection from practice. The case of the European University Association's quality review of the seven Irish universities and the Dublin Institute of Technology is cited as an example of evaluation in practice in the Irish higher education sector. Issues such as the politics and power, decision making, and the use, misuse or non-use of findings of evaluations are briefly introduced.
The Japanese Preschool System in Transition
Authors: Imoto Yuki
Published: July 2007

This article is an anthropological analysis of the recent policy reforms of the Japanese preschool system. It takes the introduction of the nintei-kodomoen (‘accredited children's centre’) as a point of entry to discuss the historical, social and political debates concerning early childhood education and care. The ‘dual system’ which characterized the post-war Japanese preschool system is undergoing change. The falling birth rate and the increasing number of women choosing to continue their careers after childbirth are bringing changes to the values of motherhood and childhood. The reforms taking place in the preschool system – which are accelerated by the political process of liberalization – both reflect and affect these changes.
Surface treatment of welded duplex stainless steels by diode laser
Authors: Capello Edoardo , Castelnuovo Moreno , Previtali Barbara , Vedani Maurizio
Published: July 2007

The good mechanical properties and the high corrosion resistance are some of the most appreciated characteristics of duplex stainless steels, which are now widely used in several application fields. One limit in the duplex stainless steel diffusion derives from their complex structure: The optimal 50%-50% austenite to ferrite ratio is lost after welding and measures must be taken to improve the as welded structure. The joint can be postweld heat treated or a filler wire having a tailored composition can be selected. As a further option, the present paper discusses the possibility of adopting a diode laser for a postweld superficial heat treatment process, aimed at recovering the balanced microstructure of the welded joint. It has been shown that the laser treatment process can lead to a ratio of austenite to ferrite close to 50%-50%. Moreover, the process has been optimized in order to increase the rate of treatment at levels acceptable for the industrial treatments (10 mm/s). Finally, the corrosion resistance of the laser treated joints were experimentally evaluated and compared to as welded and to postweld furnace heat treated specimens. The results showed that the corrosion resistance of the laser treated joints is very close to that of the furnace treated samples.
Estimating spot size and relating hole diameters with fluence and number of shots for nanosecond and femtosecond laser ablation of polyethylene terephthalate
Authors: Mullan Claire , O’Connor Gerard M. , Favre Sebastian , Ilie Diana , Glynn Thomas J.
Published: July 2007

The relationship between focused spot size, pulse energy, and ablated hole diameter was explored using 266 nm nanosecond pulses and 775 nm femtosecond pulses on polyethylene terephthalate. The spot size of a Gaussian laser beam can be deduced from the diameters of holes machined with single shots at different pulse energies but the results can be influenced by such issues as the thickness of the material and the range of fluence chosen. These limitations of the method were investigated. Multiple shot craters were also measured but gave an overestimation of spot size, particularly in the femtosecond case. A model was developed to predict the diameter for a given energy and number of shots. Tests of the model gave results that agreed well with the predicted values. It was found that for the same total energy smaller holes can be obtained by decreasing the pulse energy and increasing the number of shots. An effective spot size for multiple shots was determined.
Gas investigation for laser drilling
Authors: Schneider Matthieu , Berthe Laurent , Fabbro Rémy , Muller Maryse , Nivard Mariette
Published: July 2007

This article deals with the gas effect on percussion laser drilling in ms pulse duration range. On the one hand, the flow of assistance gas jet is investigated with and without a target using a strioscopy setup and Pitot’s tube. By this way, the position of shock waves in the supersonic jet and near the target surface is revealed. From this characterization, the distance between exit nozzle and target can be optimized to induce higher pressure on surface and protect optics from liquid ejection. On the other hand, metal liquid and vapor jets from irradiated target are observed with a high-speed camera (100 000 Img/sec). Without assistance gas, a surprising result on the video is a shock wave inside the metal vapor jet like a supersonic flow. The assistance gas limits the propagation of the vapor and facilitates the deposition of metallic liquid around the front surface holes.
Single-Pass and Multi-Pass Laser Cutting of Si–SiC: Assessment of the Cut Quality and Microstructure in the Heat Affected Zone
Authors: Quintero F. , Pou J. , Lusquiños F. , Riveiro A. , Pérez-Amor M. , Fernandes A. J. S.
Published: July 2007

Experimental investigations on the laser cutting of thick silicon infiltrated silicon carbide (Si–SiC) elements are presented. Si–SiC is a fully dense ceramic composite with high hardness and chemical and thermal stability, which makes it a valuable material in severe conditions. However, machining is still a challenging task. A pulsed Nd:YAG laser was employed to explore the quality of different techniques for the laser cutting of Si–SiC elements with a thickness of 6 mm. In this work, the feasibility of a single-pass technique in comparison with a multi-pass laser cutting was explored for different processing parameters and using both inert and reactive assist gas. A systematic evaluation of the cut quality was assessed by examination of the cross section of samples by optical and electron microscopy, compositional microanalysis, and Raman spectroscopy.
Characteristics of the laser clad metal made with powder mixture of Co-based alloy and vanadium carbide
Authors: Xu Guojian , Kutsuna Munaharu , Liu Zhognjie
Published: July 2007

A powder mixture of Co-based alloy (Stellite-6) and vanadium carbide (VC) was deposited to substrates of SM400B mild steel and SUS304 stainless steel using a 2.4 kW cw CO2 laser. The mechanism of crack for clad metal was investigated by changing the VC weight fraction in the range of 0%–56%. The microstructures of the clad layer for matrix of Co-based alloy can be classified into two types—hypoeutectic structure (0–12 wt % VC) and hypereutectic structure (13–56 wt % VC). The wear resistance and Vickers hardness of the clad layer increased with increase of VC weight fraction. The cracks of the clad metal that occurred below 573 K depend on measurement results of a temperature sensor. The fractography of the clad metal belonged to a quasicleavage fracture due to the brittle microstructures by an increase of the VC weight fraction. The crack sensitivity increased with the increase of the VC weight fraction. On the other hand, compared with substrate SM400B, substrate SUS304 showed lower crack sensitivity due to the larger thermal expansion coefficient and a lower residual stress generated on the clad metal. Namely, with substrate SUS304 shifts the critical amount of VC at which cracking appears to the higher level.
Evaluation of subsurface dentin microhardness after Er: yttrium-aluminum-garnet and Nd: yttrium-aluminum-garnet laser irradiation
Authors: Firoozmand Leily Macedo , da Silva Andressa Pereira , Gomes Torres Carlos Rocha
Published: July 2007

Background and objectives: To assess the microhardness of dentin subsurface after Er: yttrium-aluminum-garnet (YAG) and Nd:YAG laser irradiation. Study design/materials and methods: Twenty-four bovine incisors, without pulp, were used. The vestibular surface was worn out until the dentin was reached and divided in mesial and distal regions. The samples were divided into two groups: GI-distal, irradiated by Er:YAG laser, and GII-distal, irradiated by Nd:YAG laser. The mesial area was protected so as to not receive the laser irradiation. The measurements were made on Vickers digital microhardmeter. Results: For GI—there was no significant statistical difference, CI(−4.59 to 0.78), between the values of irradiated (55.61±4.38) and unirradiated (57.51±4.00) areas. For GII—the values were higher for the irradiated (62.21±6.48) compared to the unirradiated (57.82±5.42) area, CI(1.65 to 7.13). Conclusions: There was an increase of dentin microhardness when the Nd:YAG was used, but the Er:YAG did not cause significant alterations in dentin microhardness.
Interaction between laser beam, process effects, and structural properties during welding using models based on the finite element analysis
Authors: Papadakis Loucas , Hornfeck Tobias , Zaeh Michael F.
Published: July 2007

The aim of this contribution is to study the influence of the laser beam on the structural properties of sheet metals during welding by considering particular process effects. The interaction between process parameters, such as the exact positioning of the laser focus and the weld gap between sheets, affects the stability of the laser beam welding process and thus the quality of weld seams. Furthermore, additional interaction of the welding process with manufacturing tolerances and structural properties, i.e., material thinning and residual stresses after forming, influence the behavior of structures. Heat effects during and after the laser beam welding process produce residual stresses as well as phase transformation, in the case of steel alloys, in the weld seam and the heat affected zone. For this reason distortion of the whole welded structure is caused. Depending, next to the laser beam parameters, on the type of welded joint, on the structure geometry and on the clamping conditions, the residual stresses and the distortion of structures may vary. In order to examine the process design variation, three different types of welded joints were considered. A lap and a fillet seam as well as a heat conduction bead-on-plate seam on a formed sheet of steel were produced and the distortion was measured. Finally, the results are compared with the finite element analysis.
Rationale for laser classification measurement conditions
Authors: Sliney David H. , Marshall Wesley J. , Brumage E. Christopher
Published: July 2007

The basic concept of laser hazard classification with four fundamental risk groups and several subclasses is well understood by most laser users. However, many readers of laser safety standards are frequently puzzled by the rigid measurement conditions applied for hazard classification, even if this is normally a task performed by the laser manufacturer and not by a laser user or a Laser Safety Officer. The historical rationale for the measurement conditions is provided and it is emphasized that the aim of each measurement is to simulate a wide range of ocular exposure conditions that would be reasonably foreseeable worst-case viewing conditions during the use of the laser product. Measurements, if needed to compare human exposures with the maximum permissible exposure limits, emphasize actual exposure conditions and generally do not match the measurement used for hazard classification.
Positive Partial Realization Problem for Linear Discrete-Time Systems
Authors: Kaczorek Tadeusz
Published: July 2007

Positive Partial Realization Problem for Linear Discrete-Time Systems

A partial realization problem for positive linear discrete-time systems is addressed. Sufficient conditions for the existence of its solution are established. A procedure for the computation of a positive partial realization for a given finite sequence of the values of the impulse response is proposed. The procedure is illustrated by four numerical examples.
Generalized Kernel Regression Estimate for the Identification of Hammerstein Systems
Authors: Mzyk Grzegorz
Published: July 2007

Generalized Kernel Regression Estimate for the Identification of Hammerstein Systems

A modified version of the classical kernel nonparametric identification algorithm for nonlinearity recovering in a Hammerstein system under the existence of random noise is proposed. The assumptions imposed on the unknown characteristic are weak. The generalized kernel method proposed in the paper provides more accurate results in comparison with the classical kernel nonparametric estimate, regardless of the number of measurements. The convergence in probability of the proposed estimate to the unknown characteristic is proved and the question of the convergence rate is discussed. Illustrative simulation examples are included.
Endonasal Laser-Assisted Dacryocystorhinostomy
Authors: Szubin Lisa , Papageorge Ariadna , Sacks Evan
Published: July 2007

Dacryocystorhinostomy is a procedure that is performed to allow drainage of tears from the lacrimal sac directly into the nasal cavity. Endonasal telescopes facilitate performance of this operation with better visualization and decreased morbidity. We present our experience with endoscopic laser-assisted DCR. In the last 31 months, we have performed 31 procedures on 23 patients with either the holmium: YAG laser or the argon: HGM laser. We have a 97% overall success rate with a mean follow-up of 16 months. Our series includes both adult and pediatric patients as well as five revision procedures after failed external DCR. We present our technique, results, and the reasons for our change in laser delivery systems. Most importantly, we discuss the technical factors that contribute to our overall success. These include a large rhinostomy size, simultaneous correction of intranasal and/or sinus pathology, the avoidance of laser use within the lacrimal sac, and close postoperative monitoring with intranasal debridement. We conclude that endoscopic laser-assisted DCR is a better alternative to standard external DCR because it avoids a cutaneous scar, excessive tissue injury, and postoperative morbidity.
Combined Histamine H1 and H3 Receptor Blockade Produces Nasal Decongestion in an Experimental Model of Nasal Congestion
Authors: McLeod Robbie L. , Mingo Garfield G. , Herczku Christine , DeGennaro-Culver Frances , Kreutner William , Egan Robert W. , Hey John A.
Published: July 2007

We studied the pharmacological actions of combined histamine H1/H3 receptor blockade on the increase in nasal airway resistance (NAR) and decrease in nasal cavity volume produced by nasal exposure to compound 48/80, a mast cell degranulator. In the anesthetized cat compound 48/80 (1%) produced a maximum increase in NAR of 9.1 ± 0.7 cmH20·L/minute. The increase in NAR in animals pretreated with a combination of the H1 antagonist, chlorpheniramine (CTM; 0.8 mg/kg i.v.) and increasing doses of the H3 antagonist, thioperamide (THIO; 1.0, 3.0, and 10.0 mg/kg i.v.) were 6.1 ± 2.1, 4.2 ± 1.0 and 2.2 ± 0.7 cmH20·L/minute, respectively. A second H3 antagonist, clobenpropit (CLOB; 0.03, 0.3, and 1.0 mg/kg i.v.) combined with CTM (0.8 mg/kg i.v.) also inhibited the nasal effects of compound 48/80. When the nonsedating H1 antihistamine, loratadine (3.0 mg/kg i.v.), was substituted for CTM, it also reduced nasal congestion when given in combination with THIO (10 mg/kg i.v.). In contrast, treatment with CTM (1.0 mg/kg i.v.) and the H2 antagonist, ranitidine (RAN; 1.0 mg/kg i.v.) were without activity. Loratadine, CTM, CLOB, RAN, or THIO administered alone were inactive. The α-adrenergic agonist, phenylpropanolamine (PPA; 1.0 mg/kg i.v.) demonstrated decongestant effects, but in contrast to H1/H3 blockade, PPA produced a significant hypertensive effect. Using acoustic rhinometry (AcR) we found that combined i.v. CTM (1.0 mg/kg) and THIO (10 mg/kg) and combined oral CTM (10 mg/kg) and THIO (30 mg/kg) blocked the decrease in nasal cavity volume produced by intranasal compound 48/80 (1%, 50 μL). We conclude that combined H1/H3 histamine receptor blockade enhances the efficacy of an H1 antagonist by conferring decongestant activity to the H1 antihistamine. We propose that the decongestant activity of combined H1/H3 blockade may provide a novel approach for the treatment of allergic nasal congestion without the hypertensive liability of current therapies.
The Relationship of Nasal Polyps, Infection, and Inflammation
Authors: Norlander Tomas , Brönnegård Mikael , Stierna Pontus
Published: July 2007

The role of infection as cause or effect in nasal polyps is debated. In experimentally induced sinusitis in rabbits, polyps are frequent. The initial polyp formation sequence involves multiple epithelial disruptions with proliferating granulation tissue. Regenerating epithelial branches spread into the underlying connective tissue, where intraepithelial microcavities give rise to a polyp body from the adjacent mucosa. Clinical as well as experimental studies indicate that nasal polyp formation and growth are activated and perpetuated by an integrated process of mucosal epithelium, matrix, and inflammatory cells, which in turn may be initiated by both infectious and noninfectious inflammation. The complexity of the pathophysiologic events in nasal polyposis is reinforced by the finding that epithelial desquamation, combined with infection or inflammation, will initiate polyp formation. Systemic glucocorticosteroids inhibit polyp formation as well as growth of pathogenic bacteria in the sinuses of rabbits with experimental infection. Therapeutic use of corticosteroids in polyp disease, combined with antibiotics or surgery, should be modified in relation to long-term progression, intensity variations, and predisposing conditions.
Intermediate conversion kinetics in ticalcium aluminate formation
Authors: Ghoroi Chinmay , Suresh A. K.
Published: July 2007

Solid‐solid reactions are important in many chemical and metallurgical process industries, as also in the semiconductor and electrochemical materials industries. In comparison to their fluid counterparts, these systems are difficult to model with any degree of rigour, but models derived from the fluid‐solid literature have often been used with success to interpret the data. There are lacunae, however, and our previous work1 has shown the inadequacy of the conventional models when reactions take place through a network of some complexity. In that work, the conversion of alumina and calcia to C3A was shown to be a series network, with C12A7 being the (stable) reaction intermediate. The second reaction step of that network is studied here, namely the conversion of C12A7 to C3A by reaction with calcia. It has been shown that this reaction takes place in a single step. While conventional wisdom treats such reactions as taking place invariably at a (moving) reaction front, it has been shown that a proper interpretation of data requires cognizance of a volume reaction component, which may, under conditions of severe diffusion limitations, be approximated well by a front reaction. © 2007 American Institute of Chemical Engineers AIChE J, 2007
Up‐regulation of NADPH oxidase components and increased production of interferon‐gamma by leukocytes from sickle cell disease patients
Authors: Marçal Lívia E. , Dias‐da‐Motta Péricles M. , Rehder Jussara , Mamoni Ronei L. , Blotta Maria Heloísa S.L. , Whitney Constance B. , Newburger Peter E. , Costa Fernando F. , Saad Sara T.O. , Condino‐Neto Antonio
Published: July 2007

We have previously demonstrated that mononuclear leukocytes from patients with sickle cell disease (SCD) release higher amounts of superoxide compared with normal controls. The aim of this study was to further study the NADPH oxidase system in these patients by investigating gene expression of NADPH oxidase components, phosphorylation of p47phox component, and the release of cytokines related to NADPH oxidase activation in mononuclear leukocytes from patients with SCD. gp91phox gene expression was significantly higher in monocytes from SCD patients compared with normal controls (P = 0.036). Monocytes from SCD patients showed higher levels of p47phox phosphorylation compared with normal controls. INF‐γ release by lymphocytes from SCD patients was significantly higher compared with normal controls, after 48 h culture with phytohemagglutinin (P = 0.02). The release of TNF‐α by monocytes from SCD patients and normal controls was similar after 24 and 48 h culture with lipopolysaccharide (P > 0.05). We conclude that monocytes from SCD patients show higher levels of gp91phox gene expression and p47phox phosphorylation, along with increased IFN‐γ release by SCD lymphocytes. These findings help to explain our previous observation showing the increased respiratory burst activity of mononuclear leukocytes from SCD patients and may contribute to inflammation and tissue damage in these patients. Am. J. Hematol., 2008. © 2007 Wiley‐Liss, Inc.
Hemochromatosis‐associated gene mutations in patients with myelodysplastic syndromes with refractory anemia with ringed sideroblasts
Authors: Nearman Zachary P. , Szpurka Hadrian , Serio Bianca , Warshawksy Ilka , Theil Karl , Lichtin Alan , Sekeres Mikkael A. , Maciejewski Jaroslaw P.
Published: July 2007

We observed increased ferritin levels in newly diagnosed MDS‐RARS patients without transfusional iron‐overload. Hence, we hypothesized RARS patients may harbor hemochromatosis‐related mutations, which could contribute to the pathophysiology of this myelodysplastic syndromes (MDS) subset. We studied a cohort of 140 MDS patients: 42 with RARS, 10 with increased ringed sideroblasts, and 96 with other forms of MDS (43 RA, 27 RAEB, 17 RAEB‐T, 8 MDS/MPD, 1 CMML). Patients were genotyped using restriction fragment length polymorphism, designed to detect C282Y and H63D mutations of the HFE gene. We found significantly higher frequency of heterozygosity for C282Y mutation in RARS patients compared with a large control population of matched race individuals (21 vs. 9.8% in controls, P = 0.03); H63D genotype was not significantly increased. Frequency of HFE variation in other MDS subtypes failed to differ significantly from controls. Within this group, we included patients with a rare form of MDS, provisionally subclassified by WHO as RARS with thrombocytosis (RARSt). 10/14 RARSt patients were carriers of either C282Y or H63D allele significantly increased compared with the combined prevalence in a healthy population (71 vs. 33%, P < 0.01). We found expected distribution of mutant HFE alleles in patients with other forms of MDS (9.1 vs. 9.8%, P = 0.82). Increased prevalence of HFE gene mutations is not a generalized feature of MDS, but some subgroups of MDS, especially those characterized by excessive accumulation of ringed sideroblasts, exhibit C282Y mutations at a higher frequency than in other forms of MDS and healthy controls. Am. J. Hematol., 2007. © 2007 Wiley‐Liss, Inc.
Chromosome aberrations in a series of 120 multiple myeloma cases with abnormal karyotypes
Authors: Mohamed Anwar N. , Bentley Gail , Bonnett Michelle L. , Zonder Jeff , Al‐Katib Ayad
Published: July 2007

We identified 120 multiple myeloma (MM) cases with satisfactory cytogenetic evaluation and abnormal karyotypes. Hyperdiploid karyotype was found in 77 cases (64%), hypodiploid in 30 cases (25%), and the remaining 13 cases (11%) had a pseudodiploid karyotype. The most common numerical abnormalities were gains of chromosomes 15, 9, 3 followed by chromosomes 19, 11, 7, 21, and 5. Whole chromosome losses were also frequent involving primarily chromosomes X/Y, 8, 13, 14, and 22. Most cases showed also structural rearrangements leading to del(1p), dup(1q), del(5q), del(6q), del(8p), del(9p), del(13q), and del(17p). Chromosome 13/13q deletion was found in 52% of cases; complete loss of 13 was observed in 73% of cases, whereas 27% had interstitial deletions. In addition, 13/13q deletions occurred in 75% of nonhyperdiploid myeloma but only 39% of the hyperdiploid had 13/13q deletions. Translocations affecting 14q32/IGH region was seen 40 cases; t(11;14)(q13;q32) in 17 cases, t(14;16)(q32;q23) and t(8;14)(q24;q32) in three cases each, and t(6;14)(p21;q32) and t(1;14)(q21;q32) in two cases each. The remaining 14q32 translocations had various t(V;14) partners or of an undetermined origin. Remarkably, the 14q32/IGH translocations were less frequent in the hyperdiploid karyotypes than the nonhyperdiploid karyotypes (17 vs. 63%). Fourteen cases showed break at 8q24/CMYC site; seven of those had Burkitt's‐type translocations. Our results revealed that conventional cytogenetics remains an important tool in elucidating the complex and divers genetic anomalies of MM. Cytogenetics identifies two distinct groups of MM, hyperdiploid and nonhyperdiploid, and establishes the presence of prognostic chromosomal markers such as 13/13q, 17p, 8q24, and 16q aberrations. Am. J. Hematol., 2007. © 2007 Wiley‐Liss, Inc.