bluuebunny/crossref_metadata_2025 huggingface dataset:
Glycoengineering the N-acyl side chain of sialic acid of human erythropoietin affects its resistance to sialidase
Authors: Werner Anselm , Horstkorte Rüdiger , Glanz Dagobert , Biskup Karina , Blanchard Véronique , Berger Markus , Bork Kaya
Published: August 2012

During the last years, the use of therapeutic glycoproteins has increased strikingly. Glycosylation of recombinant glycoproteins is of major importance in biotechnology, as the glycan composition of recombinant glycoproteins impacts their pharmacological properties. The terminal position of N-linked complex glycans in mammals is typically occupied by sialic acid. The presence of sialic acid is crucial for functionality and affects the half-life of glycoproteins. However, glycoproteins in the bloodstream become desialylated over time and are recognized by the asialoglycoprotein receptors via the exposed galactose and targeted for degradation. Non-natural sialic acid precursors can be used to engineer the glycosylation side chains by biochemically introducing new non-natural terminal sialic acids. Previously, we demonstrated that the physiological precursor of sialic acid (i.e., N-acetylmannosamine) can be substituted by the non-natural precursors N-propanoylmannosamine (ManNProp) or N-pentanoylmannosamine (ManNPent) by their simple application to the cell culture medium. Here, we analyzed the glycosylation of erythropoietin (EPO). By feeding cells with ManNProp or ManNPent, we were able to incorporate N-propanoyl or N-pentanoyl sialic acid in significant amounts into EPO. Using a degradation assay with sialidase, we observed a higher resistance of EPO to sialidase after incorporation of N-propanoyl or N-pentanoyl sialic acid.
Processive proteolysis by γ-secretase and the mechanism of Alzheimer’s disease
Authors: Wolfe Michael S.
Published: August 2012

γ-Secretase is a membrane-embedded protease complex with presenilin as the catalytic component. Cleavage within the transmembrane domain of the amyloid β-protein precursor (APP) by γ-secretase produces the C-terminus of the amyloid β-peptide (Aβ), a proteolytic product prone to aggregation and strongly linked to Alzheimer’s disease (AD). Presenilin mutations are associated with early-onset AD, but their pathogenic mechanisms are unclear. One hypothesis is that these mutations cause AD through a toxic gain of function, changing γ-secretase activity to increase the proportion of 42-residue Aβ over the more soluble 40-residue form. A competing hypothesis is that the mutations cause AD through a loss of function, by reducing γ-secretase activity. However, γ-secretase apparently has two types of activities, an endoproteolytic function that first cuts APP to generate a 48/49-residue form of Aβ, and a carboxypeptidase activity that processively trims these longer Aβ intermediates approximately every three residues to form shorter, secreted forms. Recent studies suggest a resolution of the gain-of-function vs. loss-of-function debate: presenilin mutations may increase the proportion of longer, more aggregation-prone Aβ by specifically decreasing the trimming activity of γ-secretase. That is, the reduction of this particular proteolytic function of presenilin, not its endoproteolytic activity, may lead to the neurotoxic gain of function.
Characterisation and metabolism of astroglia-rich primary cultures from cathepsin K-deficient mice
Authors: Dauth Stephanie , Schmidt Maike M. , Rehders Maren , Dietz Frank , Kelm Sørge , Dringen Ralf , Brix Klaudia
Published: August 2012

Cathepsin K is important for the brain, because its deficiency in mice is associated with a marked decrease in differentiated astrocytes and changes in neuronal patterning in the hippocampus as well as with learning and memory deficits. As cathepsin K activity is most prominent in hippocampal regions of wild type animals, we hypothesised alterations in astrocyte-mediated support of neurons as a potential mechanism underlying the impaired brain functions in cathepsin K-deficient mice. To address this hypothesis, we have generated and characterised astroglia-rich primary cell cultures from cathepsin K-deficient and wild type mice and compared these cultures for possible changes in metabolic support functions and cell composition. Interestingly, cells expressing the oligodendrocytic markers myelin-associated glycoprotein and myelin basic protein were more frequent in astroglia-rich cultures from cathepsin K-deficient mice. However, cell cultures from both genotypes were morphologically comparable and similar with respect to glucose metabolism. In addition, specific glutathione content, glutathione export and γ-glutamyl-transpeptidase activity remained unchanged, whereas the specific activities of glutathione reductase and glutathione-S-transferase were increased by around 50% in cathepsin K-deficient cultures. Thus, lack of cathepsin K in astroglia-rich cultures appears not to affect metabolic supply functions of astrocytes but to facilitate the maturation of oligodendrocytes.
Glycan profiles of the 27 N-glycosylation sites of the HIV envelope protein CN54gp140
Authors: Pabst Martin , Chang Martina , Stadlmann Johannes , Altmann Friedrich
Published: August 2012

Hope rests on the envelope proteins of human immunodeficiency virus (HIV) as protective vaccines and thus their antibody binding sites are of prime interest. 2G12 and other human antibodies bind to a cluster of oligomannose N-glycans. Owing to the extreme number and density of N-glycosylation sites gp160 and its recombinant form gp140 represent challenging tasks for site-specific glycosylation analysis. We have conducted a glycosylation analysis of CN54gp140 by liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS) using an ion trap as well as a Q-TOF instrument and standard software for glycopeptide identification. First, a deglycosylated sample of the protease digest served to locate the elution positions of peptides covering all of the 27 potential N-glycosylation sites. Then, the assignments of the similarly eluting glycopeptides were verified by collision-induced decay MS/MS experiments with elevated fragmentation energy. The acquisition of site-specific glycan profiles was facilitated by the use of buffered eluent, which rounds up all glycoforms of a peptide into one peak. Calculation of the molecular mass drawn on the weighted averages of the glycans at each site led to the actual mass of gp140 of approximately 120 kDa.
Structural determinants of the eosinophil cationic protein antimicrobial activity
Authors: Boix Ester , Salazar Vivian A. , Torrent Marc , Pulido David , Nogués M. Victòria , Moussaoui Mohammed
Published: August 2012

Antimicrobial RNases are small cationic proteins belonging to the vertebrate RNase A superfamily and endowed with a wide range of antipathogen activities. Vertebrate RNases, while sharing the active site architecture, are found to display a variety of noncatalytical biological properties, providing an excellent example of multitask proteins. The antibacterial activity of distant related RNases suggested that the family evolved from an ancestral host-defence function. The review provides a structural insight into antimicrobial RNases, taking as a reference the human RNase 3, also named eosinophil cationic protein (ECP). A particular high binding affinity against bacterial wall structures mediates the protein action. In particular, the interaction with the lipopolysaccharides at the Gram-negative outer membrane correlates with the protein antimicrobial and specific cell agglutinating activity. Although a direct mechanical action at the bacteria wall seems to be sufficient to trigger bacterial death, a potential intracellular target cannot be discarded. Indeed, the cationic clusters at the protein surface may serve both to interact with nucleic acids and cell surface heterosaccharides. Sequence determinants for ECP activity were screened by prediction tools, proteolysis and peptide synthesis. Docking results are complementing the structural analysis to delineate the protein anchoring sites for anionic targets of biological significance.
Insights into the modulation of optimum pH by a single histidine residue in arginine deiminase from Pseudomonas aeruginosa
Authors: Ding Hanjing , Liu Hui , Yin Yan , Ding Ying , Jia Yan , Chen Qingming , Zou Guolin , Zheng Zhongliang
Published: August 2012

Arginine deiminase (ADI) is a potential antitumor agent for the arginine deprivation treatment of l-arginine auxotrophic tumors. The optimum pH of ADI varies significantly, yet little is known about the origin of this variety. Here, Pseudomonas aeruginosa ADI (PaADI), an enzyme that functions only at acidic pH, was utilized as the model system. The results of UV-pH titration imply that the nucleophilic Cys406 thiol group is protonated in the resting state. The H405R single mutation resulted in an altered pH optimum (from pH 5.5 to 6.5), an increased k
cat (from 9.8 s-1 to 101.7 s-1 at pH 6.5), and a shifted pH rate dependence (ascending limb pK
a from 3.6 to 4.4). Other mutants were constructed to investigate the effects of hydrogen bonding, charge distribution, and hydrophobicity on the properties of the enzyme. The pH optima of His405 mutants were all shifted to a relatively neutral pH except for the H405E mutant. The results of kinetic characterizations and molecular dynamic simulations revealed that the active site hydrogen bonding network involving Asp280 and His405 plays an important role in controlling the dependence of PaADI activity on pH. Moreover, the H405R variant showed increased cytotoxicity towards arginine auxotrophic cancer cell lines.
Perinatal risks after IVF and ICSI
Authors: Zollner Ursula , Dietl Johannes
Published: August 2012

Pregnancies that occur after infertility treatment, particularly after assisted reproduction, constitute high-risk pregnancies. Occurrences of conditions such as high blood pressure, preeclampsia, growth retardations and bleeding are higher in comparison with the norm of spontaneously entered pregnancies. The rate of premature births and the frequency of intrauterine deaths are much higher than the average for all pregnancies. Furthermore, pregnancies resulting from in-vitro fertilisation (IVF) have significantly higher rates of requiring induced labour or caesarean section. However, it is to be assumed that these complications and unfortunate developments are not caused by extracorporeal fertilisation itself, but rather are due to the frequency of multiples and to the risk factors of the women involved. These women are, on average, older and there are often more problems with cycle irregularities, uterine anomalies and obesity than in the total collective of all pregnancies. The methods of modern reproductive medicine often bring a higher rate of multiple pregnancies. The clinical problem of multiple pregnancies is, above all, the raised rate of premature births and intrauterine growth retardations that contribute to the significantly higher rate of morbidity and mortality for these children. The slightly higher rate of congenital defects after IVF and intracytoplasmic sperm injection (ICSI) are also attributed more to the risk profile of the parents and less to the techniques themselves. The most important and easy-to-avoid complication is the multiple pregnancy, and it should be our goal to lower this rate even further.
What do we know when we claim to know nothing? Partial knowledge of word meanings may be ontological, but not hierarchical
Authors: Stein Jeannette M. , Shore Wendelyn J.
Published: August 2012

Two studies investigated whether knowledge about ontological category membership exists early in the word learning process—specifically, when words are partially known—and if so, how such knowledge is represented. Participants made decisions about the ontological category membership of words at three levels of knowledge: words they correctly defined (known), words recognized as familiar (frontier), and words mistakenly identified as nonwords (unknown). Accuracy on this task improved as a function of word level. Participants were able to identify the broad ontological categories to which words at all three levels of knowledge belonged, as well as the more specific ontological categories to which the words belonged. Overall, results indicated that knowledge about ontological category membership is available for words at very low levels of knowledge, and that this knowledge does not necessarily follow the strict hierarchical organization some ontological systems are thought to embody (e.g. Keil 1979). Implications for the acquisition and representation of word meanings are discussed.
Elicited imitation as a measure of morphemic accuracy: Evidence from L2 Spanish
Authors: West Donna E.
Published: August 2012

This study measures whether number and type of morphemes in an elicited imitation string result in a greater number of modifications with L2 experience. Rationale is drawn from L2 working memory processing limitations at distinct levels of proficiency. 38 subjects (L2 Spanish university students) comprise three proficiency groups: beginning, undergraduate majors and graduate students. Number of morphemes was varied within each syllable count; and responses were either correct or modified (lexemically/inflectionally as deletions or substitutions). One or two way ANOVAs determined significance between mean proportions for each group. Findings indicate that increases in number of morphemes yielded significant differences, and that while the lowest proficiency group produced higher proportions of lexical deletions, the modifications made by more advanced groups were inflectional substitutions.
Nanotechnology Reviews
Authors: Grossmann Alexander , Sora Karin
Published: August 2012

No abstract available.
Investigation of fracture toughness parameters of epoxy nanocomposites for different crack angles
Authors: Fereidoon Abdolhossein , Mottahedin Lia , Latibari Sara Tahan
Published: August 2012

The effects of single-walled carbon nanotubes (SWCNTs) on the mechanical properties of nanocomposites with epoxy matrix were studied, with the emphasis on fracture toughness under tensile loading conditions. It has been demonstrated that adding CNTs into polymer-based materials can improve the mechanical properties of this material. CNTs possess a certain potential to improve the fracture toughness of epoxy systems due to their mechanical properties and increase the fracture toughness of nanocomposites. Since the fracture toughness parameters were best manifested in the scaling properties and were the main parameters, the angles of different cracks have been simulated in a 3D finite element framework and the effects of different angles of crack, on the fracture toughness of polymers, have been modeled and investigated. The simulations are run for different bias angles. The influence of angle, the crack lengths and the variations of different lengths of nanocomposite in different volume fractions (vol%) are investigated. That is to say, at first, nanocomposites had a significantly higher fracture toughness compared to the pure epoxy. We found that nanocomposites, in the presence of SWCNTs, had a greater effect on fracture toughness of nanocomposites in a greater volume of fractions. Also, the nanocomposites exhibited a significant increase in fracture toughness, with zero angle of crack compared with greater angles. In addition, it is found that at a constant volume fracture, fracture toughness, increases by increasing crack lengths.
Randomized Trial of Vitamin D Supplementation and Risk of Acute Respiratory Infection in Mongolia
Authors: Camargo Carlos A. , Ganmaa Davaasambuu , Frazier A. Lindsay , Kirchberg Franca F. , Stuart Jennifer J. , Kleinman Ken , Sumberzul Nyamjav , Rich-Edwards Janet W.
Published: August 2012

OBJECTIVE:

Observational studies suggest that serum levels of 25-hydroxyvitamin D (25[OH]D) are inversely associated with acute respiratory infections (ARIs). We hypothesized that vitamin D supplementation of children with vitamin D deficiency would lower the risk of ARIs.

METHODS:

By using cluster randomization, classrooms of 744 Mongolian schoolchildren were randomly assigned to different treatments in winter (January–March). This analysis focused on a subset of 247 children who were assigned to daily ingestion of unfortified regular milk (control; n = 104) or milk fortified with 300 IU of vitamin D3 (n = 143). This comparison was double-blinded. The primary outcome was the number of parent-reported ARIs over the past 3 months.

RESULTS:

At baseline, the median serum 25(OH)D level was 7 ng/mL (interquartile range: 5–10 ng/mL). At the end of the trial, follow-up was 99% (n = 244), and the median 25(OH)D levels of children in the control versus vitamin D groups was significantly different (7 vs 19 ng/mL; P < .001). Compared with controls, children receiving vitamin D reported significantly fewer ARIs during the study period (mean: 0.80 vs 0.45; P = .047), with a rate ratio of 0.52 (95% confidence interval: 0.31–0.89). Adjusting for age, gender, and history of wheezing, vitamin D continued to halve the risk of ARI (rate ratio: 0.50 [95% confidence interval: 0.28–0.88]). Similar results were found among children either below or above the median 25(OH)D level at baseline (rate ratio: 0.41 vs 0.57; Pinteraction = .27).

CONCLUSIONS:

Vitamin D supplementation significantly reduced the risk of ARIs in winter among Mongolian children with vitamin D deficiency.
Craniofacial Stability in Patients with Crouzon or Apert Syndrome after Le Fort III Distraction Osteogenesis
Authors: Reitsma Jacobus H. , Ongkosuwito Edwin M. , Buschang Peter H. , Adrichem Léon N.A. V , Prahl-Andersen Birte
Published: August 2012

Objective

Le Fort III osteotomy with distraction osteogenesis (DO) is used to improve the retruded midface in patients with Crouzon or Apert syndrome. This study aimed to evaluate sagittal and vertical preoperative and postoperative cephalometric changes of DO of the midface in patients with Crouzon or Apert syndrome.

Design

Population-based case-control study.

Patients and Methods

Records of patients with the syndrome of Crouzon (N = 6) or Apert (N = 7) were compared, before and after Le Fort III DO, with a nonsyndromic untreated control group (N = 486).

Main Outcome Measures

Sagittal and vertical cephalometric maxillary landmarks and measurements were used to predict and measure midface advancement and rotation after Le Fort III DO. Cephalograms were taken before surgery (T0), 4 months after surgery at removal of the distraction device (T1), and 1 year after removal of the distraction device (T2).

Analysis

Z scores were performed to compare cephalometric measures of syndromic patients with control subjects.

Results

Cephalograms of 13 patients with Crouzon syndrome (N = 6) or Apert (N = 7) (age range 8.2 to 19.8 years) were evaluated. Treatment changes (T1-T2) showed statistically significant maxillary advancement, with no significant differences between the patients with the Crouzon or Apert syndrome.

Conclusions

DO of the midface in patients with Crouzon or Apert syndrome seems to be stable in the sagittal direction after follow-up. Although Crouzon and Apert differ after DO, anteroposterior craniofacial dimensions were significantly improved and were closer to patterns of normal subjects.
Randomized Multicenter and Stratified Phase II Study of Gemcitabine Alone Versus Gemcitabine and Docetaxel in Patients with Metastatic or Relapsed Leiomyosarcomas: A Fédération Nationale des Centres de Lutte Contre le Cancer (FNCLCC) French Sarcoma Group Study (TAXOGEM study)
Authors: Pautier Patricia , Floquet Anne , Penel Nicolas , Piperno-Neumann Sophie , Isambert Nicolas , Rey Annie , Bompas Emmanuelle , Cioffi Angela , Delcambre Corinne , Cupissol Didier , Collin Françoise , Blay Jean-Yves , Jimenez Marta , Duffaud Florence
Published: August 2012

Background.

This study aimed to evaluate the efficacy and toxicity of single-agent gemcitabine versus gemcitabine plus docetaxel as second-line therapy in patients with uterine and nonuterine leiomyosarcoma (LMS).

Patients and Methods.

Patients had metastatic or unresectable LMS and had received one prior anthracycline-based regimen. A total of 90 patients received either single-agent gemcitabine (arm A; gemcitabine, 1,000 mg/m2 i.v. for 100 minutes on days 1, 8, and 15 of a 28-day cycle) or a combination of gemcitabine and docetaxel (arm B; gemcitabine, 900 mg/m2 i.v. for 90 minutes on days 1 and 8, plus docetaxel, 100 mg/m2 i.v. for 1 hour on day 8 of a 21-day cycle with lenograstim). The primary endpoint was the objective response rate.

Results.

The objective response rates were 19% and 24% in arm A (gemcitabine) and arm B (gemcitabine plus docetaxel), respectively, for patients with uterine LMS. For patients with nonuterine LMS, the objective response rates were 14% and 5% for arms A and B, respectively. The median progression-free survival times for arms A and B were 5.5 months and 4.7 months, respectively, for patients with uterine LMS. For patients with nonuterine LMS, the median progression-free survival times were 6.3 months and 3.8 months for arms A and B, respectively. One toxic death occurred in arm B.

Conclusions.

Both single-agent gemcitabine and gemcitabine plus docetaxel were found to be effective second-line therapies for leiomyosarcomas, with a 3-month progression-free survival rate of 40% for LMS with both uterine and nonuterine sites of origin. Single-agent gemcitabine yielded results similar to those of gemcitabine plus docetaxel in this trial, but patients using single-agent gemcitabine experienced less toxicity.
Experimental behaviour of compacted marls
Authors: CARDOSO R. , MARANHA DES NEVES E. , ALONSO E.E.
Published: August 2012

Jurassic marls from Abadia, Portugal, were used in the construction of some motorway embankments. Large fragments of this evolving material remained after the construction process, and their degradation was of concern because of the expected change of the engineering properties of the compacted material. The material exhibits a very complex behaviour, which is difficult to reproduce with existing constitutive models for unsaturated structured materials. This paper focuses on understanding and providing data on the interaction between the pure marls (rock) and the aggregate behaviour. It presents the main results of tests performed to characterise the hydro-mechanical behaviour of compacted marls in specimens prepared with different grading size distributions and subjected to oedometer tests where both stress and suction changes were applied. The experimental data obtained were analysed, considering the presence of fragments and their degradation. The marl matrix was characterised to complete the existing data previously published for this material, but now with the purpose of providing a better explanation for the volumetric behaviour of the aggregate. The discussion is assisted by the explanation provided by a simple elasto-plastic model for unsaturated soils. Discrepancies with model predictions help to highlight the singularity of the marl aggregate. Compacted marls behave as materials in the transition between rockfill (when the fragments remain brittle) and a clayey soil (when the degradation accumulates). Therefore the compacted marl exhibits a dual behaviour. If it is dry, deformations are explained by the breakage of particles and rearrangement of the structure. If it is wet, the compacted marl is dominated by bond degradation of the material, the release of swelling potential and simultaneous changes in the stiffness and strength of the fragments. It appears that the transition from dry to wet can be identified by the current suction; moreover, it is rather abrupt.
Simulation-Based Learning: It’s Not Just for NRP
Authors: Pilcher Jobeth , Heather Goodall , Jensen Cynthia , Huwe Valerie , Jewell Cordelia , Reynolds Regina , Karlsen Kris A.
Published: August 2012

Simulations are experiential learning opportunities during which participants can learn new information, as well as have the opportunity to apply previous knowledge. While hands-on learning has been incorporated into NRP and similar training for some time, simulation-based learning is increasingly being utilized in new and varied situations. This article begins with a general overview of simulation, along with a brief review of the historical background of mannequins and simulation. This is followed by several mini-articles describing how the authors have applied simulated-based activities to promote learning. The article concludes with a look at the potential future of simulation-based education.
Violence Victimization of Young Men in Heterosexual Relationships: Does Alcohol Outlet Density Influence Outcomes?
Authors: Waller Martha W. , Iritani Bonita J. , Flewelling Robert L. , Christ Sharon L. , Halpern Carolyn Tucker , Moracco Kathryn E.
Published: August 2012

This study examined whether alcohol outlet density is associated with male physical and sexual victimization by a female partner. Data were from the National Longitudinal Study of Adolescent Health (Add Health). A total of 3,179 young adult men identified a current heterosexual relationship and had complete intimate partner violence (IPV) victimization data. Almost 16% of this sample reported being the victim of physical only IPV in their relationship over the previous 12 months; an additional 6.4% were victims of sexual only or sexual and physical IPV. Multivariate analyses indicated high alcohol outlet density was associated with greater odds of experiencing physical IPV only (odds ratio [OR] = 2.07). Heavy drinkers experienced increased odds of physical and sexual IPV victimization. Alcohol outlet density should be addressed in prevention efforts.
Bystander Perceptions: Implications for University Sexual Assault Prevention Programs
Authors: Koelsch Lori E. , Brown Amy L. , Boisen Leah
Published: August 2012

The college party environment comprises a risk factor for unwanted sexual activity but may also provide a safety net, given the presence of bystanders who can potentially intervene in risky situations. Sexual assault prevention programs are increasingly incorporating bystander education into their designs. This article presents findings intended to inform these programs. Qualitative data from single-sex focus groups about typical college party behavior was analyzed for common themes. Analysis of these themes suggests that although some sexual behavior is visible at college parties, most sexual behavior is assumed to occur behind closed doors. In addition, intervention and prevention methods may vary by gender. Multiple factors appear to promote or dissuade bystander intervention in college party situations.
Effects of the functional groups attached to aromatic organic compounds on their adsorption onto preloaded activated carbon
Authors: Zhaoyang Lu , Bicun Jiang , Aimin Li
Published: August 2012

The adsorption of phenol, p-nitrophenol, aniline, and nitrobenzene onto a commercial granular activated carbon (GAC: F400) preloaded with tannic acid (TA), a model background contaminant, was investigated. Compared with virgin GAC, the adsorption capacities of the four selected aromatic organic compounds (AOCs) onto GACs preloaded with TA at three densities were affected significantly. Also, the relationship between the adsorption capacities of AOCs and the characteristics of GACs was further discussed and clarified in this manuscript. The differences in the functional groups attached to the AOCs did not affect the similar linear relationship between the micropore surface area and their capacities to AOCs. However, the adsorption capacities of AOCs on TA-loaded GAC were affected by the different functional groups on the four AOCs: 67.6% of the capacity of aniline for virgin F400 remained on F400c (a preloaded GAC), compared with 23.8, 25.9, and 36.5% of phenol, p-nitrophenol, and nitrobenzene, respectively. The diversity of adsorption behavior of the four AOCs with different substituents was the result of hybrid contributions, such as hydrogen bonding, hydrophobic effect and aromatic stacking.
Optimising dissolved air flotation/filtration treatment of algae-laden lagoon effluent using surface charge: a Bolivar treatment plant case study
Authors: Yap Russell , Holmes Michael , Peirson William , Whittaker Michael , Stuetz Richard , Jefferson Bruce , Henderson Rita
Published: August 2012

Dissolved air flotation (DAF) incorporating filtration (DAFF) is used at the Bolivar wastewater treatment plant (WWTP) to polish lagoon effluent for reuse. Elevated algal populations are frequently experienced and can lead to increased coagulant requirements and process control issues. Streaming current detectors (SCDs) and a charge demand analyser (CDA) were used to monitor the full-scale plant. This was followed by an optimisation study using a pilot plant with a CDA. It was found that the normal operational charge demand range for DAF at Bolivar was between −46 and −40 μeq L−1. Decreasing the pH of coagulation reduced coagulant consumption and facilitated more sensitive CDA responses to changes in alum dose.
Catalytic ozonation for odour removal of high temperature alumina refinery condensate
Authors: Wang Xinguang , Guan Jing , Stuetz Richard M.
Published: August 2012

Odour emissions from aluminium processing can cause an impact on local communities surrounding such facilities. Of particular concern is fugitive odours emitted from the handling and use of refinery condensate streams, particularly the digestion condensate. This study evaluated the application of using catalytic ozonation to treat alumina refinery condensate in order to remove the potential emission of odourous compounds from the industrial wastewater. The technical challenges in treating the alumina refinery condensate are the high pH and temperatures of the wastewater effluent (over 80 °C and pH above 10) due the industrial process. The odour removal efficiencies for different catalysts (FeCl3, MnO, and MnSO4) under experimental conditions in terms of controlled pH, temperature and ozone dosage were determined before and after ozone treatment using dynamic olfactometry. The result demonstrated that the addition of both FeCl3 and MnO catalysts improved odour removal efficiencies during the ozonation of alumina condensates at similar pH and temperature conditions. FeCl3 and MnO had similar enhancement for odour removal, however MnO was determined to be more appropriate than MnSO4 for odour removal due to the colouration of the treated condensate.
Trepan drilling of fuel injection nozzles with a TEM00 Nd:YAG slab laser
Authors: Rohde H. , Meiners E.
Published: August 2012

Holes of 160 μm diameter were trepan drilled in fuel injection nozzles of 1 mm thickness by means of a TEM00 fundamental mode Nd:YAG slab laser. Two different types of holes have been trepan drilled: at an angle of 90°, and at an angle of 60° to the metal surface. The influence of nozzle distance, focal position, gas pressure, pulse repetition frequency and trepanning velocity on the hole diameter and on the conicity are investigated. A diameter accuracy of ±10 μm and a conicity of 3% were achieved. One hole is drilled in 7–25 seconds in dependence of the drilling strategy.
Obtaining laser safety at a synchrotron radiation user facility: The Advanced Light Source
Authors: Barat Kenneth
Published: August 2012

The Advanced Light Source (ALS) is a United States national facility for scientific research and development located at the Lawrence Berkeley National Laboratory in California. The ALS delivers the world's brightest synchrotron radiation in the far ultraviolet and soft X-ray regions of the spectrum. As a ‘user facility’ it is available to researchers from industry, academia, and laboratories from around the world. Subsequently, a wide range of safety concerns become involved. This article relates not only to synchrotron facilities but to any ‘user’ facility. A growing number of US centers are attracting organizations and individuals to use the equipment on site, for a fee. This includes synchrotron radiation and/or free electron facilities, specialty research centers, and laser job shops. Personnel coming to such a facility bring with them a broad spectrum of safety cultures. Upon entering, the guests must accommodate to the host facility safety procedures. This article describes a successful method to deal with that responsibility.
Theoretical and experimental studies of thick-section cutting with a chemical oxygen–iodine laser (COIL)
Authors: Kar A. , Scott J. E. , Latham W. P.
Published: August 2012

A simple mathematical model of thick-section stainless steel cutting with a high power chemical oxygen–iodine laser (COIL) is presented and compared with experimental results obtained with a 10-kilowatt COIL at the U.S. Air Force's Phillips Laboratory. This model uses a lumped-parameter technique to relate the cutting kerf depth with various process parameters and can be used to predict scaled laser materials processing performance to very thick sections. The model is similar to an empirical model developed by researchers in Japan, but includes predictive capabilities for thick metal cutting at very low velocities. The effects of various process parameters such as laser power, spot size and dimensions, and processing speed in the cutting depth are discussed and demonstrated. Finally, the ramifications of this model on thick-section processing of metals are presented, with emphasis on potential applications of COIL to high-speed, thick stainless steel cutting.
On the relation between fluid dynamic pressure and the formation of pores in laser keyhole welding
Authors: Dowden John , Kapadia Phiroze , Clucas Andy , Ducharme R. , Steen W. M.
Published: August 2012

In the laser welding of metals with a continuous CO2 laser, a hole containing a partially ionized metal vapor is formed throughout the depth of the material. A full description of flow conditions inside this hole is needed for a complete understanding of the process, but much can be learned from a simpler analysis of this aspect of the problem. The balance of forces that keeps the keyhole open can be investigated in this way. Such a model shows that over most of the keyhole's length, the dominant force keeping the keyhole open against surface tension is the fluid mechanical pressure in the plasma rather than the ablation pressure. This has a bearing on the problem of the formation of pores in the interior of the welded material. It is clearly observable on films made of the surface of the weld piece and of cross-sections through it that the keyhole has some of the characteristics of instability. It is shown that under some circumstances the balance of pressure against the forces of surface tension can be sufficiently great for cavities within the molten material to be formed. Estimates can then be made for the spacing of these cavities.
The role of oxygen pressure in laser cutting mild steels
Authors: Ivarson A. , Powell J. , Magnusson C.
Published: August 2012

This paper presents the results of an experimental program investigating the effects of using high pressure oxygen as assist gas in combination with a pulsed laser while cutting medium thick mild steel plates. It was discovered that if the pulse conditions are optimized, the maximum cutting speed for a set average laser power could be increased by up to 10% compared to low oxygen pressure continuous wave (CW) laser cutting. The assist gas was found to have two optimum pressure ranges between which the material suffered from burning on the cut edge. The paper presents a phenomenological model to explain the changes in cut front dynamics as the oxygen pressure is increased and the role of pulsing in suppressing edge burning.
Some aspects of laser heating of engineering materials
Authors: Yilbas B. S. , Al-Garni A. Z.
Published: August 2012

Laser induced heating processes are important when a laser is used as a machine tool in industry, since the quality of the machining process strongly depends on the heating mechanism. The present study examines a heat transfer model that provides useful information on the laser induced interaction mechanism. Steady state and time dependent heating models are introduced and temperature profiles inside the materials are predicted. Using appropriate assumptions, the time for the surface temperature to reach 90% of its steady state value is estimated. To validate the theoretical predictions, experiments are performed to measure the surface temperature of the irradiated spot during the laser heating pulse. It is found that, during the use of a pulsed laser in the drilling process, as the heating progresses the drilling velocities rise while the liquid depth and time to reach steady state fall, in this case, the energy consumed for evaporation is higher than losses through conduction.
Taking advantage of laser properties to enhance demonstrations and student laboratories
Authors: Brill Michele L.
Published: August 2012

This paper reflects the proceedings of a workshop for local educators provided by Camden County College Laser Curriculum faculty which addressed the question: ‘How can the teacher take advantage of laser properties to improve or enhance demonstrations and student labs?’ Explored here are illustrative ways in which to utilize, for educational purposes, the three well-known characteristics of lasers: directionality, monochromaticity, and coherence. There is a faculty overlap between the Physics Department and the Laser Curriculum faculty at the college. The use of lasers in the classroom, then, has a two-fold purpose: first, to teach about lasers, and second, to teach with lasers. The first objective is accomplished largely in a new facility, the Laser Institute of Technology for Education and Research (LITER building), a free-standing building housing laser and fiber-optic programs. It features a wide selection of lasers and allows use of various tuning options of some of them for demonstrations and student labs connected with optics classes and other laser curriculum courses. The Physics Department provides the usual Class II or lower (for safety reasons) lasers to be used for demonstrations and student labs. Physics classes are at three levels: preparatory, college (algebra-based), and transfer (calculus-based). The lasers permit ground to be covered quickly and effectively at all levels. A current project at the transfer curriculum level will be described.
Laser surface alloying of magnesium base alloys
Authors: Galun R. , Weisheit A. , Mordike B. L.
Published: August 2012

The feasibility of the laser surface alloying of magnesium base alloys with aluminum, copper, nickel and silicon has been shown in this work. By laser alloying with these elements, using a 5 kW CO2-laser, the hardness of several magnesium base alloys can be increased to values above 250 HV0.1. Melted depths from 700–1200 μm and alloying contents from 15–55 at % were achieved. The wear resistance of the alloyed surface layers was examined using the scratch test method. Investigations on the corrosion behavior of the layers were performed using the salt water immersion test. The results of this investigation showed that the greatest improvement in wear resistance occurred for copper alloyed layers, whereas aluminum alloyed layers showed a superior corrosion resistance.
Validation of the Saskatoon Falls Prevention Consortium's Falls Screening and Referral Algorithm
Authors: Lawson Sara Nicole , Zaluski Neal , Petrie Amanda , Arnold Cathy , Basran Jenny , Dal Bello-Haas Vanina
Published: August 2012

Purpose: To investigate the concurrent validity of the Saskatoon Falls Prevention Consortium's Falls Screening and Referral Algorithm (FSRA). Method: A total of 29 older adults (mean age 77.7 [SD 4.0] y) residing in an independent-living senior's complex who met inclusion criteria completed a demographic questionnaire and the components of the FSRA and Berg Balance Scale (BBS). The FSRA consists of the Elderly Fall Screening Test (EFST) and the Multi-factor Falls Questionnaire (MFQ); it is designed to categorize individuals into low, moderate, or high fall-risk categories to determine appropriate management pathways. A predictive model for probability of fall risk, based on previous research, was used to determine concurrent validity of the FSRI. Results: The FSRA placed 79% of participants into the low-risk category, whereas the predictive model found the probability of fall risk to range from 0.04 to 0.74, with a mean of 0.35 (SD 0.25). No statistically significant correlation was found between the FSRA and the predictive model for probability of fall risk (Spearman's ρ=0.35, p=0.06). Conclusion: The FSRA lacks concurrent validity relative to to a previously established model of fall risk and appears to over-categorize individuals into the low-risk group. Further research on the FSRA as an adequate tool to screen community-dwelling older adults for fall risk is recommended.
Optimization of Two-Stage Peltier Modules: Structure and Exergetic Efficiency
Authors: Olivares-Robles Miguel Angel , Vazquez Federico , Ramirez-Lopez Cesar
Published: August 2012

In this paper we undertake the theoretical analysis of a two-stage semiconductor thermoelectric module (TEM) which contains an arbitrary and different number of thermocouples, n1 and n2, in each stage (pyramid-styled TEM). The analysis is based on a dimensionless entropy balance set of equations. We study the effects of n1 and n2, the flowing electric currents through each stage, the applied temperatures and the thermoelectric properties of the semiconductor materials on the exergetic efficiency. Our main result implies that the electric currents flowing in each stage must necessarily be different with a ratio about 4.3 if the best thermal performance and the highest temperature difference possible between the cold and hot side of the device are pursued. This fact had not been pointed out before for pyramid-styled two stage TEM. The ratio n1/n2 should be about 8.
Replication of Holograms with Corn Syrup by Rubbing
Authors: Mejias-Brizuela Nildia Y. , Olivares-Pérez Arturo , Ortiz-Gutiérrez Mauricio
Published: August 2012

Corn syrup films are used to replicate holograms in order to fabricate micro-structural patterns without the toxins commonly found in photosensitive salts and dyes. We use amplitude and relief masks with lithographic techniques and rubbing techniques in order to transfer holographic information to corn syrup material. Holographic diffraction patterns from holographic gratings and computer Fourier holograms fabricated with corn syrup are shown. We measured the diffraction efficiency parameter in order to characterize the film. The versatility of this material for storage information is promising. Holographic gratings achieved a diffraction efficiency of around 8.4% with an amplitude mask and 36% for a relief mask technique. Preliminary results using corn syrup as an emulsion for replicating holograms are also shown in this work.
Miniaturized Integrated Platform for Electrical and Optical Monitoring of Cell Cultures
Authors: Moldovan Carmen , Iosub Rodica , Codreanu Cecilia , Firtat Bogdan , Necula Daniel , Brasoveanu Costin , Stan Ion
Published: August 2012

The following paper describes the design and functions of a miniaturized integrated platform for optical and electrical monitoring of cell cultures and the necessary steps in the fabrication and testing of a silicon microchip Micro ElectroMechanical Systems (MEMS)-based technology for cell data recording, monitoring and stimulation. The silicon microchip consists of a MEMS machined device containing a shank of 240 μm width, 3 mm long and 50 μm thick and an enlarged area of 5 mm × 5 mm hosting the pads for electrical connections. Ten platinum electrodes and five sensors are placed on the shank and are connected with the external electronics through the pads. The sensors aim to monitor the pH, the temperature and the impedance of the cell culture. The electrodes are bidirectional and can be used both for electrical potential recording and stimulation of cells. The fabrication steps are presented, along with the electrical and optical characterization of the system. The target of the research is to develop a new and reconfigurable platform according to the particular applications needs, as a tool for the biologist, chemists and medical doctors working is the field of cell culture monitoring in terms of growth, maintenance conditions, reaction to electrical or chemical stimulation (drugs, toxicants, etc.). HaCaT (Immortalised Human Keratinocyte) cell culture has been used for demonstration purposes in order to provide information on the platform electrical and optical functions.
Hospitalization patterns and outcomes of infants with Influenza A(H1N1) in Kuwait
Authors: Husain Entesar H , AlKhabaz Ahmad , Al-Qattan Hanan Y , Al-Shammari Nufoud , Owayed Abdullah F
Published: August 2012

Introduction: Infants represent an important risk group for influenza associated hospitalizations and mortality. This study evaluated the clinical presentations, hospitalization course and outcome of infants hospitalized with the pandemic influenza A H1N1 [Influenza A(H1N1)pdm09] in relation to their previous health status. Methodology: We conducted a retrospective chart review of hospitalized infants with laboratory-confirmed Influenza A(H1N1)pdm09 infection in two hospitals in Kuwait. Demographic characteristics, pre-existing high-risk medical conditions, clinical presentations, complications and mortality were analyzed. Previously healthy infants’ data were compared with infants with pre-existing high-risk medical conditions for severity of the illness and outcome. Results: We identified 62 infants comprising 32% of all admissions with Influenza A(H1N1)pdm09.  The median age ± SD was 7 ± 4 months.  Nineteen (31%) had pre-existing high-risk medical conditions. Complications were documented in 53% of previously healthy infants compared to 47% in high-risk infants.  Mean duration of hospitalization was 4.9 days in healthy infants and 6.7 for infants with high-risk medical conditions. Bacterial pneumonia complicated 7% of previously healthy infants compared to 26% with high-risk conditions (P = 0.03). Four infants (6.5%) required admission to the intensive care unit (ICU), of whom three had high risk medical condition. Conclusion: The majority of hospitalized infants with Influenza A(H1N1)pdm09 were previously healthy. Prolonged hospitalization, ICU admission and mortality were more observed in infants with high-risk medical conditions. According to the latest Advisory Committee on Immunization Practices (ACIP) recommendations, annual influenza vaccination is recommended for any child six months of age and older, particularly those with risk factors.
Successful public health response to four cases of imported measles in Panama
Authors: Sosa Nestor , Guerra Ilka , Abrego Leyda , Cisneros Julio , Castillo Juan , Nieto-Guevara Javier , Gálvez Carlos , Moltó Yadira , Smith Rebecca E , Pascale Juan Miguel
Published: August 2012

In Panama, the last endemic cases of measles occurred in 1995. In this paper, we report four cases of imported measles in three girls and one boy after they returned from a trip to Poland and Israel between 28 April and 11 May 2011. The etiologic diagnosis of the four cases was confirmed by detection of IgM antibodies against measles virus and positive polymerase chain reaction using measles-specific primers. All cases had genotype D4 with close genetic similarity to virus reported from Poland. Public health interventions included isolation of the cases in their homes and an extensive search for and vaccination of contacts of the four cases, regardless of their vaccination status. A nationwide vaccination campaign was also implemented after the first case was identified. A total of 70,950 measles vaccine doses were administered in Panama in the two months following the identification of these cases. In addition, 94,179 persons were confirmed to have their immunization schedule up-to-date and did not receive the vaccine. No secondary cases were detected in Panama in the following six months.