Higher-order Level Research Articles

Quantifying microorganisms during biooxidation of arsenite and bioleaching of zinc sulfide

The development of molecular tools for the detection and quantification of both species as well as functional traits, aids in a better understanding and control of microbial processes. Presently, these methods can also be used to assess the activity of these organisms or functions, even in complex ecosystems and difficult matrices such as ores and low pH samples. In this paper we present the versatility of one of these tools, Q-PCR, to allow accurate and fast insight in changes in two types of microbial processes representing two ways in which microbes can interact with metals, bioleaching and bioprecipitation. Using the Q-PCR technique it was possible to identify and quantify the thermoacidophilic archaeon Acidianus sp. to be the main microbial strain responsible for biooxidation of arsenite in a low pH reactor. The method was also used to study the dynamics between the iron oxidizing and sulfur oxidizing acidophiles during bioleaching of a zinc concentrate in a batch reactor system and showed that the iron oxidizer Leptospirillum ferriphilum that dominated the starting culture disappeared upon addition of the concentrate. Gradually, bacterial activity was regained starting with growth of sulfur oxidizers and at later stage iron oxidizers started to grow. Molecular analysis can be used to direct research to the relevant organisms involved and concentrate on improving their application (in the arsenite case Acidianus sp.) or in understanding appearances and disappearances of microorganisms (during leaching of zinc concentrate the disappearance of Leptospirillum after high inoculation levels) in order to allow optimization of leaching efficiencies at the lowest (oxygen) costs.

Ultrathin 2D Coordination Polymer Nanosheets by Surfactant-Mediated Synthesis

Low-dimensional nanostructures offer a host of intriguing properties which are distinct from those of the bulk material, owing to size-confinement effects and amplified surface areas. Here, we report on the scalable, bottom-up synthesis of ultrathin coordination polymer nanosheets via surfactant-mediated synthesis and subsequent exfoliation. Layers of a two-dimensional (2D) zinc coordination polymer are self-assembled in the interlamellar space of a reverse microemulsion mesophase into stacks of nanosheets interleaved with cethyltrimethylammonium bromide (CTAB) at regular intervals, thus giving rise to a lamellar hybrid mesostructure with a lattice period of ~8 nm and an underlying highly crystalline substructure. The basic structural motif is composed of 2D acetato-benzimidazolato-zinc layers of tetrahedrally coordinated zinc joined together by anionic acetate and benzimidazolate ligands. The hierarchical structure was studied by PXRD, TEM, EDX, EELS, AFM, and solid-state NMR spectroscopy, revealing a high level of order on both the atomic and mesoscale, suggesting fairly strong interactions along the organic-inorganic hybrid interface. Exfoliation of the hybrid material in organic solvents such as THF and chloroform yields sheet- and belt-like nanostructures with lateral sizes between 10's and 100's of nanometers and a height of about 10 nm measured by AFM, which precisely maps the basal spacing of the lamellar mesostructure; further exfoliation results in nanobelts with minimum sizes around 4 nm. Finally, the sheetlike nanostructures behave as morphological chameleons, transforming into highly regular multiwalled coordination polymer nanotubes upon treatment with organic solvents.

Supramolecular Organization in Organic–Inorganic Heterogeneous Hybrid Catalysts Formed from Polyoxometalate and Poly(ampholyte) Polymer

Hybridization of polyoxometalates (POMs) via the formation of an organic-inorganic association constitutes a new route to develop a heterogeneous POM catalyst with tunable functionality imparted through supramolecular assembly. Herein, we report on strategies to obtain tunable well-defined supramolecular architectures of an organic-inorganic heterogeneous hybrid catalyst formed by the association of a hydrophobically substituted polyampholyte copolymer (poly N, N-diallyl-N-hexylamine-alt-maleic acid) and phosphotungstic acid (H3PW12O40) POMs. The self-assembling property of the initial polyampholyte copolymer matrix is modulated by controlling the pH of the hybridization solution. When deposited on a mica surface, isolated, long and extended polymer chains are formed under basic conditions (pH 7.9), while globular or coiled structures are formed under acidic conditions (pH 2). The supramolecular assembly of the POM-polymer hybrid is found to be directed by the type and quantities of charges present on the polyampholyte copolymer, which themselves depend on the pH conditions. The hypothesis is that the Keggin type [PW12O40](3-) anions, which have a size of ~1 nm, electrostatically bind to the positive charge sites of the polymer backbone. The hybrid material stabilized at pH 5.3 consists of POM-decorated polymer chains. Statistical analysis of distances between pairs of POM entities show narrow density distributions, suggesting that POM entities are attached to the polymer chains with a high level of order. Conversely, under acidic conditions (pH 2), the hybrid shows the formation of a core-shell type of structure. The strategies reported here, to tune the supramolecular assembly of organic-inorganic hybrid materials, are highly valuable for the design and a more rational utilization of POM heterogeneous catalysts in several chemical transformations.

Effects of temperature on modulation of oxidative stress and antioxidant defenses in testes of tropical tasar silkworm Antheraea mylitta

High temperatures are known to cause physiological stress in organisms. This is often associated with enhanced generation of reactive oxygen species (ROS) leading to oxidative damage. The commercially important tropical tasar silkworm Antheraea mylitta has to endure high summer temperature before egg production on the onset of monsoon. In this study the status of pro-oxidants and antioxidants was studied in the testes of male pupae of tasar silkworm A. mylitta under thermal stress condition. Further, to find out the impact of temperature on physiological activity, oxygen consumption rate was measured. The result indicated higher level of thiobarbituric acid reactive substances (TBARS, as an index of lipid peroxidation) and total hydroperoxides in the male pupae exposed to high temperature (40±1°C). Similarly, it was found that increased levels of antioxidants such as superoxide dismutase (SOD), catalase (CAT), glutathione-S-transferase (GST), ascorbic acid (ASA) and low molecular thiols (L-SH) in testes are more prominent in high temperature rather than in moderate temperature (35±1oC) suggesting the activation of physiological mechanism to scavenge the ROS produced during stress. Further more, the order of higher level of oxygen consumption rate was observed as high temperature (40±1°C) > moderate temperature (35±1°C) > control groups (28±1°C). Oxygen consumption rate was positively correlated with oxidative stress and antioxidant defence indices. We infer from these findings that the testes of A. mylitta pupae modulate testicular antioxidant responses to thermal stress.

A new corruption index based on individual attitudes

The aim of this paper is to propose a new corruption index based on individual attitudes referring to the European citizens. The index is defined by means of the person location parameters estimated by a partial credit model (PCM). This model is particularly suitable since the synthetic value of the interest latent variable 'Corruption Perception' is first evaluated at individual level; its estimated scores are then naturally aggregated to higher levels in order to obtain a measure at Europe and nation–wide.

Structure and rheology of branched polyamide 6 polymers from their reaction recipe

The structure and rheology of randomly branched polyamide melts, in particular that of branched polyamide 6, are predicted on the basis of their initial reaction recipe. To this end, a Monte Carlo approach has been developed in order to build different molecular architectures from the initial reactant monomers at the appropriate conversion level. This approach allows us to analyze the composition of these melts in terms of topological architecture and molecular weight of the various polymer species present. Subsequently, the linear rheology of each sample is predicted within the tube model framework [van Ruymbeke et al., Macromol. 2006], based on the position/seniority of the different branches in these polymer species, by averaging over a limited number of representative segments. This approach allows us to discuss the role the different polymer architectures play in the overall viscoelastic response, the importance of the different initial monomers to adequately tune the composition (and thus the rheology) of these branched systems and the necessity of reaching a high conversion level in order to obtain a large zero-shear viscosity. We also extend this approach by applying a bimodal distribution to describe the solid state polycondensation of these products. The predictions are in good agreement with experiments. This method may be applied to any branched polymer product that is synthesized via a melt condensation type reaction and can be used as a tool to test and screen in detail the flow properties of materials without prior synthesis.

Влияние деформации на магнитные свойства сплавов на основе Ni3Al

Deformation can lead both to increase, and to decrease the values of the magnetic susceptibility of alloys based on Ni₃Al. The difference in the behavior of alloys takes place due to the different structure of the alloy as a result of the deformation. The formation of a nanocrystalline structure in intermetsllid Ni₃Al leads to decrease of degree of order in the alloy as whole, and to the decrease of the magnetic susceptibility. During the deformation of heat-resistant alloys inside intermetallic particles of Ni₃Al with a high level of order locally appear the defects complexes, within which a long-range order is destroyed. These complexes can be considered as ferromagnetic clusters, the occurrence of which increases the magnetic susceptibility of the initial paramagnetic alloy.<br />

Saccharomyces cerevisiaeLinker Histone—Hho1p Maintains Chromatin Loop Organization during Ageing

Intricate, dynamic, and absolutely unavoidable ageing affects cells and organisms through their entire lifetime. Driven by diverse mechanisms all leading to compromised cellular functions and finally to death, this process is a challenge for researchers. The molecular mechanisms, the general rules that it follows, and the complex interplay at a molecular and cellular level are yet little understood. Here, we present our results showing a connection between the linker histones, the higher-order chromatin structures, and the process of chronological lifespan of yeast cells. By deleting the gene for the linker histone in Saccharomyces cerevisiae we have created a model for studying the role of chromatin structures mainly at its most elusive and so far barely understood higher-order levels of compaction in the processes of yeast chronological lifespan. The mutant cells demonstrated controversial features showing slower growth than the wild type combined with better survival during the whole process. The analysis of the global chromatin organization during different time points demonstrated certain loss of the upper levels of chromatin compaction in the cells without linker histone. The results underlay the importance of this histone for the maintenance of the chromatin loop structures during ageing.

Hierarchical personality traits and the distinction between unipolar and bipolar disorders

BackgroundThe association between personality and psychopathology can provide an insight into the structure of mental disorders and the shared etiology and pathophysiology underlying diagnoses with overlapping symptomatology. The majority of personality-psychopathology research pertinent to the mood disorders has focused upon traits at the higher-order levels of the personality hierarchy, rather than those at intermediate or lower levels. The purpose of the current investigation was to investigate whether unipolar and bipolar mood disorders, and the severity of depressive and manic symptoms, show differential associations with traits at multiple levels of the personality hierarchy. MethodsParticipants (N=275; 63% women; mean age 42.95 years) with depressive disorders (n=139) and bipolar disorders (n=136), as assessed by the Structured Clinical Interview for DSM-IV, Axis I Disorders, Patient Version (SCID-I/P; First et al., 1995), completed the Hamilton Depression Rating Scale, Young Mania Scale, Revised NEO Personality Inventory and Big Five Aspect Scales. ResultsResults support the hypothesis that lower levels of the personality hierarchy provide additional differentiation of affective pathology. As compared to the widespread association of depressive symptoms with traits across the personality hierarchy, manic symptoms demonstrated more specific associations with traits at lower levels of the personality hierarchy. LimitationsPatients with severe mania were excluded, thus the full range of mania is not represented in the current sample. ConclusionsThese results support the use of lower-order personality traits to discriminate between unipolar versus bipolar mood disorder, and are consistent with changes proposed to the psychiatric nosology to increase diagnostic precision.

Isolated Bacterial Chemosensory Array Possesses Quasi- and Ultrastable Components: Functional Links between Array Stability, Cooperativity, and Order

Bacteria utilize a large multiprotein chemosensory array to sense attractants and repellents in their environment. The array is a hexagonal lattice formed from three core proteins: a transmembrane receptor, the His kinase CheA, and the adaptor protein CheW. The resulting, highly networked array architecture yields several advantages including strong positive cooperativity in the attractant response and rapid signal transduction through the preformed, integrated signaling circuit. Moreover, when isolated from cells or reconstituted in isolated bacterial membranes, the array possesses extreme kinetic stability termed ultrastability (Erbse and Falke (2009) Biochemistry 48:6975-87) and is the most long-lived multiprotein enzyme complex described to date. The isolated array retains kinase activity, attractant regulation, and its bound core proteins for days or more at 22 °C. The present work quantitates this ultrastability and investigates its origin. The results demonstrate that arrays consist of two major components: (i) a quasi-stable component with a lifetime of 1-2 days that decays due to slow proteolysis of CheA kinase in the lattice and (ii) a truly ultrastable component with a lifetime of ~20 days that is substantially more protected from proteolysis. Following proteolysis of the quasi-stable component the apparent positive cooperativity of the array increases, arguing the quasi-stable component is not as cooperative as the ultrastable component. Introduction of structural defects into the array by coupling a bulky probe to a subset of receptors reveals that modification of only 2% of the receptor population is sufficient to abolish ultrastability, supporting the hypothesis that the ultrastable component requires a high level of array spatial order. Overall, the findings are consistent with a model in which the quasi- and ultrastable components arise from distinct regions of the array, such that the ultrastable regions possess more extensive, better-ordered, multivalent interconnectivities between core components, thereby yielding extraordinary stability and cooperativity. Furthermore, the findings indicate that the chemosensory array is a promising platform for the development of ultrastable biosensors.

Hydration Shell Parameters of Aqueous Alcohols: THz Excess Absorption and Packing Density

Solvation in water requires minimizing the perturbations in its hydrogen bonded network. Hence solutes distort water molecular motions in a surrounding domain, forming a molecule-specific hydration shell. The properties of those hydration shells impact the structure and function of the solubilized molecules, both at the single molecule and at higher order levels. The size of the hydration shell and the picoseconds time-scale water dynamics retardation are revealed by terahertz (THz) absorption coefficient measurements. Room-temperature absorption coefficient at f = 0.28 [THz] is measured as a function of alcohol concentration in aqueous methanol, ethanol, 1,2-propanol, and 1-butanol solutions. Highly diluted alcohol measurements and enhanced overall measurement accuracy are achieved with a THz absorption measurement technique of nL-volume liquids in a capillary tube. In the absorption analysis, bulk and interfacial molecular domains of water and alcohol are considered. THz ideal and excess absorption coefficients are defined in accordance with thermodynamics mixing formulations. The parameter extraction method is developed based on a THz excess absorption model and hydrated solute molecule packing density representation. First, the hydration shell size is deduced from the hydrated solute packing densities at two specific THz excess absorption nonlinearity points: at infinite alcohol dilution (IAD) and at the THz excess absorption extremum (EAE). Consequently, interfacial water and alcohol molecular domain absorptions are deduced from the THz excess absorption model. The hydration shell sizes obtained at the THz excess absorption extremum are in excellent agreement with other reports. The hydration shells of methanol, ethanol, 1- and 2-propanol consist of 13.97, 22.94, 22.99, and 31.10 water molecules, respectively. The hydration shell water absorption is on average 0.774 ± 0.028 times the bulk water absorption. The hydration shell parameters might shed light on hydration dynamics of biomolecules.

Use of the fluorescent probe LAURDAN to label and measure inner membrane fluidity of endospores of Clostridium spp.

A method for measuring the fluidity of inner membranes of populations of endospores of Clostridium spp. with a fluorescent dye was developed. Cells of Clostridium beijerinckii ATCC 8260 and Clostridium sporogenes ATCC 7955 were allowed to sporulate in the presence of 6-dodecanoyl-2-dimethylaminonaphthalene (LAURDAN) on a soil-based media. Labeling of endospores with LAURDAN did not affect endospore viability. Removal of the outer membranes of endospores was done using a chemical treatment and confirmed using transmission electron microscopy (TEM). Two-photon confocal laser scanning microscopy (CLSM), and generalized polarization (GP) measurements were used to assess fluorescence of endospores. Lipid composition analysis of cells and endospores was done to determine whether differences in GP values are attributable to differences in membrane composition. Removal of the outer membranes of endospores did not significantly impact GP values. Decoated, labeled endospores of C. sporogenes ATCC 7955 and C. beijerinckii ATCC 8260 exhibited GP values of 0.77±0.031 and 0.74±0.027 respectively. Differences in ratios of fatty acids between cells and endospores are unlikely to be responsible for high GP values observed in endospores. These GP values indicate high levels of lipid order and the exclusion of water from within inner membranes of endospores.

Orderings and signatures of higher level on multirings and hyperfields

AbstractMultirings are objects like rings but with multi-valued addition. In the present paper we extend results of E. Becker and others concerning orderings of higher level on fields and rings to orderings of higher level on hyperfields and multirings and, in the process of doing this, we establish higher level analogs of the results previously obtained by the second author. In particular, we introduce a class of multirings called ℓ-real reduced multirings, define a natural reflection A ⇝ Qℓ-red(A) from the category of multirings satisfying to the full subcategory of ℓ-real reduced multirings, and provide an elementary first-order description of these objects. The relationship between ℓ-real reduced hyperfields and the spaces of signatures defined by Mulcahy and Powers is also examined.

EEG characteristics and visual cognitive function of children with attention deficit hyperactivity disorder (ADHD)

Using visual and auditory continuous performance tests (CPT) and EEG, cognitive function and EEG power were investigated in patients with attention deficit hyperactivity disorder (ADHD). CPT and EEG were conducted for 44 ADHD children and 44 healthy controls of comparable age and sex. The EEG power tests include relative power of theta, alpha, and beta, and theta/beta and theta/alpha ratios. ADHD patients showed significantly higher theta relative power, lower beta relative power, and higher theta/beta ratio (p<0.05). ADHD patients showed a significantly lower score of auditory CPT (p<0.05). The EEG power characteristics were correlated significantly with the visual attention function in ADHD children (p<0.01). Higher-order level cognitive dysfunction affects ADHD pathogenesis. Cortical hypoarousal effects on several mechanisms including the fronto-striatal circuitry may be implicated in the inhibition of prepotent and premature responses.

Lessons from biomass planning at national and regional level in the EU

AbstractAction plans are an important tool for meeting the EU renewable energy targets. Planning of biomass at national level has recently shifted from biomass action plans to renewable energy action plans; the latter still assigning special attention to biomass. A number of regions have also developed or are developing biomass plans. However, even though such plans are to assist the delivery of bioenergy development, the processes leading to successful implementation are not well documented. Little is known of the roles and function of these plans. This paper examines factors underlying plans and draws lessons from the planning processes that appear to support successful bioenergy development. The work presents views of actors involved in biomass planning in eleven countries and nine regions in Europe with an analytical framework employed to condense and present interview content. The analysis shows that while planning processes at both national and regional levels have encountered barriers – most of them common to policy implementation in general, but some specific to bioenergy policy – the national level appears to have better dealt with such barriers. Stakeholder commitment, continuity of policy, and flexibility of planning guidelines and processes were found as some of the keys to successful implementation. While biomass plans were demonstrated to serve several roles, approaches looking beyond energy use are still limited. The work concludes that coordination of planning between jurisdictional levels needs to be strengthened and regional stimuli recognized at higher levels in order for biomass policy and planning to better achieve goals. © 2012 Society of Chemical Industry and John Wiley &amp; Sons, Ltd

The Effect of Computerized Provider Order Entry on Medical Students’ Ability to Write Orders

Background: Computerized provider order entry (CPOE) is being implemented at increasing numbers of U.S. hospitals, yet the effects of CPOE on medical student education are largely unstudied. Purpose: The objective is to investigate the effects of CPOE on medical students’ ability to write orders for patients. Methods: One hundred forty-three medical students who began their Basic Medicine clerkship between March 2003 and April 2004 were asked to write mock admission orders for a patient with pneumonia after the 1st month of their clerkship. Students had spent the month at 1 of 3 hospitals: 1 using CPOE, 1 paper orders, and 1 that began using CPOE midway through this study. Admission orders were scored for the presence of specific orders and features. Results: One hundred twenty students attempted to write admission orders. Students who trained at hospitals using CPOE and those who trained at hospitals using paper orders included expected basic, lifesaving, and higher level orders at similar rates. No significant differences in order clarity or inclusion of unnecessary orders were found for the 2 groups. No significant differences were found when controlling for school year and 4 modifiable rotation features. Conclusions: When admission order completeness and quality for medical students who trained at hospitals using CPOE were compared to those who trained using handwritten orders, no important differences were found.

NANO ACCURACY ELEVATION OF ULTRA-PRECISION MACHINING USING OPTICAL FIBER LASER ENCODER SYSTEM

The ultra-precision products which recently experienced high in demands had included the large areas of most updated technologies, for example, the semiconductor, the computer, the aerospace, the media information, the precision machining. For early 21st century, it was expected that the ultra-precision technologies would be distributed more throughout the market and required securing more nation-wise advancements. Furthermore, there seemed to be increasing in demand of the single crystal diamond tool which was capable of the ultra-precision machining for parts requiring a high degree of complicated details which were more than just simple wrapping and policing. Moreover, the highest degree of precision is currently at 50nm for some precision parts but not in all. The machining system and technology should be at very high preformed level in order to accomplish this degree of the ultra-precision.

Ordered Collagen Membranes: Production and Characterization

A collagen membrane with microscopic order is presented. The membranes were produced with acid-soluble collagen, using two different methods to obtain orientation. The product was characterized by mean of UV and IR spectra, scanning electronic microscopy, optical microscopy and laser diffractometry. The results clearly show a high level of order in the membranes obtained by both techniques. Permeability for rifamycin, ascorbic acid and NaCl was also measured. Due to the characteristics of the membranes, they have a potential application for treatment of surface injuries.

QUASI-STATIONARY SOLITONS FOR LANGMUIR WAVES IN PLASMAS WITH FULL NONLINEARITY

The quasi-stationary solitons for Langmuir waves in plasmas is obtained in this paper. This model is governed by the perturbed nonlinear Schrödinger's equation with cubic and power law nonlinearities. The perturbation terms are considered with full nonlinearity. A new generalized definition of the phase of the soliton is introduced. This leads to additional information at higher order level which soliton perturbation theory fails to capture.

Students’ Perceptions of Dynamics Concept Pairs and Correlation with Their Problem-Solving Performance

A concept pair is a pair of concepts that are fundamentally different but closely related. To develop a solid conceptual understanding in dynamics (a foundational engineering science course) and physics, students must understand the fundamental difference and relationship between two concepts that are included in each concept pair. However, all existing research in dynamics and physics education has been focused on the identification and repair of students’ misunderstanding of individual concepts, but not concept pairs. The present research fills the gap of existing research by studying students’ perceptions of dynamics concept pairs and correlation with their problem-solving performance in both particle and rigid-body dynamics. A total of 88 engineering undergraduate students participated in the present study. Students’ perceptions were assessed using a 40-item instrument that included 20 dynamics concept pairs at fundamental Level One and higher-order Level Two. Students’ problem-solving performance was assessed using four exams that included 66 dynamics problems. The coefficients of reliability (Cronbach’s α) of assessment instruments vary between 0.69 and 0.93. The research findings from the present study show that students were not confident in their understanding of Level-Two concept pairs, especially the relationship between the Principle of Linear Impulse and Momentum and the Principle of Angular Impulse and Momentum, and the relationship between the Principle of Angular Impulse and Momentum and the Conservation of Angular Momentum. A statistically significant correlation exists between students’ perceptions of Level-Two concept pairs and their problem-solving performance on both particle dynamics (r = 0.355, p < 0.01) and rigid-body dynamics (r = 0.351, p < 0.01). The research findings made from the present study imply that educational efforts should be focused on improving students’ understanding of Level-Two dynamics concept pairs.