Order Polynomial Relationship Research Articles

Physical and aerodynamic properties of date palm pollen grains

The present study was designed to determine the effect of four moisture content levels (4, 5, 6, and 7 %) on the physical and aerodynamic properties of date palm pollen grain (DPP). The physical properties of DPP included pollen length (L), width (w), thickness (T), projected area (Ap), geometric mean diameter (dg), mass (m), sphericity (S), and bulk density (ρp). It was observed that the moisture content did not significantly influence the physical properties of the DPP. The aerodynamic properties of DPP included the terminal velocity (Vt), drag coefficient (Dc), drag force (Df), and Reynolds number (Re). The pollen Reynolds number (Re) is significant at different pollen grain moisture content, and regression models were developed in the form of polynomial and exponential relationships. Also, the 3rd order polynomial relationship was found between Re and Dc. The results showed that the average values of Vt, Dc, Df, and Re were about 0.6 m s-1, (0.38 to 0.45), 1.09E-11 N, and (0.29 to 0.42), respectively. The results of this study will be helpful in the performance of date palm pollination machines.

Study On Activation Energy, Moisture Diffusivity Effectiveness and Mathematical Modelling of Thin Layer Drying Kinetics of Red Pepper (Capsicum Annum L.)

The thin-layer drying behavior of red pepper sample was examined using seven mathematical models that were found in the literature. According to the R2, RMSE, and v2 values with respect to the experimental and predicted moisture ratios the models were contrasted. The drying process happened throughout the period of falling rates. The findings demonstrated that the most acceptable model is the Midilli model for describing the drying behavior of thin layer pepper samples. The effective moisture diffusivity and moisture content were shown to be correlated by a third order polynomial relationship. As the moisture content of the pepper samples decreased the moisture diffusivity effectiveness increased, with an energy activation of 40.54 KJ/mol, the average effective diffusivity over the temperature range investigated was between 4.7 x 10-9 to 13.3 x 10-9 m2/sec.

Determination and comparison of effective moisture diffusivity of carrot (core and cortex) during hot air drying

AbstractThe moisture content and shrinkage of a sample are often ignored when determining its effective moisture diffusivity (EMD), which will result in a larger error in simulating the dynamic moisture diffusion process during drying. This work aimed to determine the EMDs of cortex and core in axial and radial directions considering the combined influence of moisture content and shrinkage of material. The drying and shrinkage characteristics of cortex and core were investigated under different hot air drying conditions, and the EMDs of the cortex and core in different drying stages were determined by the slope method considering the moisture content and shrinkage. The results showed that the EMDs were dependent on the carrot component rather than its directions. The EMDs of the core and cortex were different. It decreased slowly at the early drying stage, and decreased sharply at the later drying stage, and increased with the hot air temperature increasing. A third order polynomial relationship was established to correlate the EMDs with the moisture content and hot air temperature (R2 > 0.9460), and was verified by experiments. The maximum weighted absolute percentage error of the moisture content from simulation and experiment was only 6.11%, more accurate than that based on a constant effective moisture diffusivity (CEMD) for characterizing the intrinsic moisture diffusion in carrot during drying.Practical applicationsThe EMD is an important parameter that characterizes intrinsic moisture diffusion in material and often used for modeling and calculation in food drying. The investigation methods developed in this study can be applied for determining the EMD of samples with shrinkage and variable moisture content. This study would be helpful for understanding the moisture transfer mechanism and optimizing operation conditions in carrot drying industry.

Effects of dietary carbohydrate levels on growth, metabolic enzyme activities and oxidative status of hybrid snakehead (Channa maculata ♀ × Channa argus ♂)

An 8-week feeding trial was aimed to explore the effects of dietary carbohydrate on growth performance, metabolic enzyme activities and oxidative status of hybrid snakehead (Channa maculata ♀ × Channa argus ♂). A total of 540 healthy hybrid snakehead with initial body weight of (39.4 ± 0.01) g were selected and randomly divided into 18 cages, with 30 in each cage. Six isonitrogenous and isolipidic diets with different levels of digestible carbohydrate (α-starch) levels (DCL) (0%, 5%, 10%, 15%, 20% and 25%) were fed to hybrid snakehead. Results showed that dietary carbohydrate supplementation had significant effects on final body weight (FW), weight gain (WG), feed conversion ratio (FCR) and protein efficiency ratio (PER) of hybrid snakehead in a third order polynomial (cubic) model, with the optimal level established at 10.2%–12.0%. Effects on Condition factor (CF) of hybrid snakehead was described by a second order polynomial (quadratic) relationship. Hepatosomatic index (HSI) and viscerosomatic index (VSI) showed a linear relationship with increasing DCL. The body protein, crude lipid and hepatic glycogen content of hybrid snakehead increased with the levels of carbohydrate supplementation (P < 0.05). Dietary supplementation with carbohydrate significantly increased the levels of plasma cholesterol (CHOL), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C) and low-density lipoprotein cholesterol (LDL-C) in hybrid snakehead (P < 0.05). The activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in both plasma and liver were significantly enhanced by the highest level of carbohydrate (P < 0.05). Furthermore, the levels of superoxide dismutase (SOD) and catalase (CAT) in liver increased firstly and then decreased with the increasing of DCL (P < 0.05). The expression levels of genes encoding SOD, glutathione peroxidase (GSH-PX), proinflammatory cytokines interleukin 1β (IL-1β) and interleukin 8 (IL-8) in liver showed significantly increasing trend when DCL increased from 0% to 15%, followed by significant decline when DCL exceeds 15% (P < 0.05). The malondialdehyde (MDA) contents in liver were not affected by DCL. Based on these results, the optimal level of dietary carbohydrate supplementation was estimated at approximately 11% for maximum growth and normal metabolism of hybrid snakehead.

Thermal Expansion of 3C-SiC Obtained from In-Situ X-ray Diffraction at High Temperature and First-Principal Calculations.

In situ X-ray crystallography powder diffraction studies on beta silicon carbide (3C-SiC) in the temperature range 25–800 °C at the maximum peak (111) are reported. At 25 °C, it was found that the lattice parameter is 4.596 Å, and coefficient thermal expansion (CTE) is 2.4 ×/°C. The coefficient of thermal expansion along a-direction was established to follow a second order polynomial relationship with temperature ). CASTEP codes were utilized to calculate the phonon frequency of 3C-SiC at various pressures using density function theory. Using the Gruneisen formalism, the computational coefficient of thermal expansion was found to be 2.2 ×/°C. The novelty of this work lies in the adoption of two-step thermal expansion determination for 3C-SiC using both experimental and computational techniques.

Assessment of the temporal variation of electrical potential and pH of different bleaching agents

IntroductionTooth whitening procedures are under continuous investigation to improve esthetic outcomes and reduce bleaching sensitivity (BS) precipitating from treatments. During the dental bleaching process it is known that the release of free radicals degrades the organic pigment molecules of the tooth and with this an amount of energy is released. Nonetheless, previous studies have never investigated the temporal correlation between of pH and electric potential (EP) generated in this treatment. ObjectivesTherefore, the objective of the present study was to investigate temporal variations of pH and EP associated with three different commercially available bleaching gels and the correlation levels between parameters of interest to provide relevant information regarding the kinetics of oxidation reactions in dental bleaching procedures. MethodsThe study was divided into 3 groups (n = 9) in function of hydrogen peroxide concentration (either 6%, 15% and 35%). The temporal evolution of pH and EP values were determined using a highly-accurate and previously calibrated pH meter at specific time-points (5, 10, 15 and 30 min). ResultsData obtained were submitted to one-way ANOVA of repeated measures with Bonferroni post-test (α = 0.05). The results of the study showed difference in the factor gel concentration (p < 0,0001), time (p < 0,0001) and interaction (gel/time) (p = 0.002) while throughout the intervals evaluated the groups remained relatively stable and without significant difference in the intragroup variation of pH (p < 0.05) and in EDP only with significant difference in the 5 min interval of the 35% concentration. A 2nd order polynomial relationship test showed high correlation levels. ConclusionIt can thus be concluded that there is a negative relationship between EP and pH variation in the different gel concentrations. Clinical significanceThe findings of the present study suggest that bleaching gels of higher concentration may provoke BS that are more intense and durable due to significant electric depolarization of neuronal extensions of pulpal tissues.

Hay Yield and Water Use Efficiency of Alfalfa under Different Irrigation and Fungicide Regimes in a Semiarid Climate

Alfalfa is one of the most nutritive and high-yielding forage legumes planted in rotation with cereal crops across the United States. Under semiarid and arid climates with limited water resources, sustainable management of the available resources is required. The objective of this study was to investigate the effect of different irrigation regimes and fungicide applications on alfalfa in the high desert region of the Colorado Plateau of the U.S. Field experiments were conducted during the 2012–2014 period. Alfalfa was planted in fall 2012, uniformly irrigated for crop establishment and subjected to seven different irrigation regimes after the first cut in spring 2013. Alfalfa was treated by fungicide application and was harvested at 10% blooming. The maximum amounts of applied water were 350, 300, 208, and 312 mm, respectively, during the first, second, third, and fourth regrowth cycles in 2013, and 373, 282, 198, and 246 mm in 2014 for the respective regrowth cycles in 2014; the seasonal applied irrigation amount varied from 711 to 1171 mm in 2013 and from 328 to 1100 mm in 2014. The results showed non-significant effect of fungicide application on the forage yield. Alfalfa forage yield was significantly affected by the irrigation regimes and showed a third order polynomial relationship with the applied irrigation amounts during each regrowth cycle and on seasonal scale. Forage yield decreased from the first cut to the fourth cut and the annual forage varied from 10.6 to 25.7 Mg/ha for the treated alfalfa and from 11.5 to 25.6 Mg/ha for the non-treated alfalfa. Forage yield at each cut accounted for 39.6, 24.2, 17.6, and 18.6% of the 2013 season forage yield and 31.4, 23.8, 21.6, and 23.2% of the 2014 season forage yield, for the first, second, third, and fourth cut, respectively. Alfalfa water use efficiency varied from 0.06 to 3.3 kg/m3. The relationships developed in this study could be used by forage growers, crop consultants, and project managers for decision making and planning to improve the productivity of water under the semiarid and arid climate of New Mexico and the surrounding regions.

Seasonal Occurrence of Potato Psyllid (Bactericera Cockerelli) and Risk of Zebra Chip Pathogen (Candidatus Liberibacter Solanacearum) in Northwestern New Mexico.

Potato psyllid (Bactericera cockerelli) is one of the most important pests in potatoes (Solanum tuberosum L.) due to its feeding behavior and the transmission of a bacterium (Candidatus Liberibacter solanacearum) that causes zebra chip disease, altering the quality of the potato tuber and the fried potato chip or french fry. This pest is thus a threat to the chip potato industry and often requires preventive measures including the use of costly insecticides. The objectives of this research were to monitor the variation in B. cockerelli adult abundance and to evaluate the risk of zebra chip disease in northwestern New Mexico, USA. Yellow sticky traps were used to collect the pest at the Agricultural Experiment Station at Farmington, NM and in nearby commercial fields at the Navajo Agricultural Products Industry (NAPI) and Navajo Mesa Farms during the 2017–2019 period. The collected adult pests were analyzed at Texas A & M University for the presence of Candidatus L. solanacearum (Lso). The results showed field infestation by B. cockerelli in early June and that the population peaked during the second half of July and decreased as the potato growing season progressed. However, a second less important peak of the pest was revealed around mid- to late-August, depending on the growing season and field. While the B. cockerelli population increased linearly with average air temperature, it showed strong third order polynomial relationships with the accumulated thermal units and the Julian days. The test of B. cockerelli for the Lso infection revealed a low incidence of the pathogen varying from 0.22% to 6.25% and the infected adult B. cockerelli were collected during the population peak period. The results of this study may be helpful to potato growers in pest management decision-making and control. However, more study is needed to evaluate zebra chip disease in terms of its prevention and economic impact, and to develop economic thresholds and pest management programs for northwestern New Mexico and neighboring regions.

A Dosimetry Study of Portable X-ray Fluorescence in Vivo Metal Measurements.

Portable x-ray fluorescence devices have grown in popularity for possible metal exposure assessment using in vivo measurements of bone and toenail. These measurements are accompanied by a small radiation dose, which is typically assessed by radiation safety committees to be minimal. However, an understanding of precise dose under different instrument conditions is still needed. This study set out to do a thorough investigation of the exact dose measurements using optically stimulated dosimeters, thermoluminescent dosimeters, and simulation with a Monte Carlo N-Particle transport code to assess the skin and total-body effective dose typical of portable x-ray fluorescence devices. We showed normal linear relationships between measurement time, x-ray tube current, and radiation dose with the device, and we showed a second order polynomial relationship with increasing voltage and radiation dose. Dose was quantified using thermoluminescent dosimeters, optically stimulated dosimeters, and simulations, which gave similar dose estimations. Skin dose for a standard 50-kV, 40-μA measurement for bone and toenail in vivo was 48.5 and 28.7 mSv, respectively, according to simulation results. Total-body effective dose was shown as 3.4 and 2.0 μSv for in vivo bone and toenail measurements, respectively, for adults using the portable x-ray fluorescence device.

Estimation of crop evapotranspiration through spatial distributed crop coefficient in a semi-arid environment

Accurate and reliable estimation of reference crop evapotranspiration (ETo) is important due to its critical role in determining crop water requirement in irrigated agriculture. The aim of the paper was to estimate the evapotranspiration (ETc) using spatially distributed crop coefficient (Kc) and open access earth observing datasets in a semi-arid environment. We have estimated the actual evapotranspiration (ETc) based on spatially distributed crop coefficient (Kc) using following models namely Surface Energy Balance Algorithm for Land (SEBAL), Makkink model, Hargreaves and Samani model, Camargo method and Jensen-Haise model. Further, these models estimates were compared with Penman-Monteith estimate.Comparative evaluation of models was performed through statistical tests, and it was found that the Makkink model performed satisfactory compared with standard Penman-Monteith model estimate (R2 = 0.88). Leaf area index (LAI) and the Kc was in strong (second order polynomial) relationship (R2 = 0.98). The analysis also shows distributed actual evapotranspiration based on Makkink model has good agreement with actual evapotranspiration from Penman-Monteith with R2 of 0.84, respectively, for the study area. The finding suggests that the Makkink model estimates ETo are very close to the universally accepted Penman-Monteith model based ETo.

Validated and rapid measurement of the ferric reducing antioxidant power in plasma samples

The ferric reducing antioxidant power assay was developed using rat plasma samples and validated according to the Food and Drug Administration guidelines as well as strategies for the lack of endogenous compounds-free samples of matrix. For validation procedures, the phosphate buffered saline solution was used as the artificial matrix because this led to a direct interpolation in calibration curves. The absorbance responses and antioxidant activities in curves showed a second order polynomial relationship (R2 value = 0.9982). The precision, accuracy, and stability of the method ranged from 1.7 to 7.2%, 89.8 to 100.0%, and 82.7 to 111.6%, respectively. This assay had a short time of analysis (96 samples per min) and absence of interferences during the spectrophotometric monitoring. For the application of the method, the plasma antioxidant capacity, blood distribution of levofloxacin, and biometry hematic were evaluated in samples obtained from rats under different experimental conditions. The in vitro condition applied to blood samples increased the plasma antioxidant capacity and volume of erythrocytes, whereas diminished the levofloxacin concentration in these cells. The high antioxidant activity was produced by a high amount of inosine, which in turn was caused by high oxidative stress leading to an impaired blood distribution of levofloxacin and erythrocyte swelling. This assay is a validated and rapid biomarker for the evaluation of the total antioxidant capacity in plasma samples.

Prediction of filtrate suspended solids and solids capture based on operating parameters for belt filter press

The control and optimization of belt filter presses in the wastewater treatment industry is still largely dependent on operator intervention. This is mainly due to the lack of predictive models for belt filter press performance. This paper presents correlations determined via a factorial trial for the determination of filtrate suspended solids and solids capture as a function of individual process parameters as well as their interactions. A Box–Behnken experimental based design methodology was used to examine the relationship between the operating parameters and the response variables. The process parameters investigated were polymer concentration, polymer dosing, sludge flow rate and the belt speed. The measured responses were the filtrate suspended solids and sludge cake solids. The measured responses obeyed a second order polynomial relationship and their respective interaction effects of the operating parameters were illustrated on three-dimensional surface graphs. The sludge cake solids concentration was found to be constant over the wide range of experimental conditions. The interaction between the sludge flow rate and polymer dosing rate was the second most influential operating parameter on the filtrate suspended solids following sludge flow rate. The belt speed had an insignificant influence on the filtrate suspended solids and solids capture. The correlation is useful to determine the optimum amount of polymer required if the sludge flow rate changes due to production requirements for constant feed solids concentrations and can be used to develop automated control systems for a particular WWTP.

An alternative method for predicting relative humidity for climate change studies

The reliable prediction of climate variables at finer temporal resolutions, e.g. daily scale, is essential for climate change impact analysis. However, humidity variables remain less focused, although probable changes under changing climate conditions and their effect on impact studies can be significant. The potential of the daily minimum air temperature (Tn) downscaled from general circulation models (GCMs) to predict ground-scale relative humidity in climate change studies is presented. Daily data over 50 years for Sendai city were obtained from the Japan Meteorological Agency. For GCM data, the INMCM4 model developed by the Institute for Numerical Mathematics, Russia, was selected. Statistically downscaled Tn was used with the linear or second order polynomial relationships developed for each calendar month using observed relative humidity and Tn. This produced predicted relative humidity using the alternative method. Furthermore, relative humidity was directly downscaled using the relative humidity results from the GCM. The results from the two methods were compared with the observed relative humidity data based on the root mean square error and the Kolmogorov–Smirnov test. Results based on root mean square error indicate that the predictions made using the downscaled Tn were less satisfied only for June and September compared to the results from the direct downscaling method. Moreover, the predicted relative humidity using the downscaled Tn matched rather well with the observations for 8 months (except for March, July, August and October) with calculated p values above the 0.05 level. Notably, the proposed method achieved better performance in the winter months when the directly downscaled method failed to satisfy the Kolmogorov–Smirnov test.

Microwave assisted Soxhlet extraction of essential oil from Vietnamese Star anise fruits (Illicium verum Hook.f.) and their chemical composition

The influence of microwave power (W), irradiation time (h) and particle size (P) on the yield of extraction and composition of essential oil from Illicium verum Hook.f has been assessed by means of a new experimental design. The combined effects of three factors above on the yield of extraction of essential oil Y% (r.m) have been determined using Doehlert matrices in the range of 100 - 400 W for microwave power, 10 - 40 mins for irradiation time and 0.4 - 2.0 mm for particle size. In these conditions, second order polynomial relationship between Y% (r.m) and these factors have been established with regression coefficients close to 0.93. The major effect of microwave power and particle size on the yield of extraction of essential oil has been highlighted. In the conditions of 325 W microwave power, 20 min irradiation time and 0.4 mm particle sizes, the highest essential oil yield by microwave assisted Soxhlet extraction was 8.3%. The main compound of Illicium verum Hook.f was the (E)-anethole (92 %). The composition of α-pinene, β-mycrene, α-phellandren were absent from the essential oil extracted from Illicium verum Hook. f. by use of MASE.

Waves of El Niño-Southern Oscillation and Influenza Pandemics

Influenza pandemics have occurred at irregular intervals for over 500 years, unlike seasonal influenza epidemics which occur annually. Although the risk factors are known, the basis for the timing of influenza pandemic waves are unknown. Coherence of peaks of El Nino and influenza pandemic in 2009–2010, however, suggests that both waves are coupled. This study was done to determine the relation of influenza pandemics to the peaks and waveforms of El Nino southern oscillation (ENSO). ENSO cycles from 1871–2015 which had El Nino phases were windowed from Multivariate El Nino Index. Influenza pandemic peaks were mapped to ENSO monthly time series. ENSO waveforms were compared graphically, and fitted to nonstationary cosinor models. Second order polynomial regression model was fitted to the peak and duration of El Nino. Agglomerative hierarchical cluster of ENSO waveforms was performed. All influenza pandemic peaks mapped to El Nino peaks, with lags of 0–5 months. ENSO waveforms during influenza pandemics share parameters of oscillation. Nonstationary cosinor models showed that ENSO cycles are complex waves. There was second order polynomial relationship between peak and duration of El Ninos, p < 0.0001. ENSO waveforms clustered into four distinct groups. ENSO waveforms during influenza pandemics of 1889–1900, 1957–1958, and 1968–1969 linked closely. ENSO indices were significantly high from 7–16 months after onset of cycles, p < 0.0001. Surveillance for El Nino events to forecast periods of maximal transmission and survival of influenza A viruses is, therefore, crucial for public health control strategies.

Study the effect of tool geometry and operational conditions on mouldboard plough forces and energy requirement: Part 2. Experimental validation with soil bin test

Forces acting on tillage tools directly affect vehicle fuel consumption of tillage operations. Both tool forces and soil disturbance are a function of tillage tool type, tool geometry, and operational conditions. A soil bin experiment in a sandy loam soil was conducted to validate the results obtained from the finite element method (FEM) simulation of the interaction between soil and a mouldboard plough, carried out in part 1 of this study. An octagonal load cell was used to measure the draught and vertical forces. A special support was manufactured to modify the cutting angle (alpha) and the lifting angle (beta). Tillage forces and soil disturbance were measured for different speed (0.5, 1, 1.5, and 2m/s), depth (100, 150, 200, and 250mm), cutting (30°, 45°, 60°, and 75°), and lifting (25°, 40°, and 55°) angles, and were presented for the same soil conditions of those considered in the FEM. The soil disturbance including the width and surface area of the cut soil, and the height, width, and the surface area of the soil inversion were measured with a laser scanner. Results showed that both the FEM calculations and the soil bin measurement presented the same tendency for the variation of draught and vertical forces with speed, depth, cutting, and lifting angles. The maximum error recorded between the measured and the FEM results was 33.8%. It was found that the draught and vertical forces increased linearly with speed, whereas a second order polynomial and linear relationships were established with depth, respectively. Draught increased linearly with both the cutting and lifting angles, whereas, the vertical force decreased linearly with these angles. The study of the soil disturbance showed that the operating conditions (speed, depth, and cutting angles) of the mouldboard plough had an important effect on the quality of the tillage (soil loosening and inversion). Both the FEM and the soil bin tests showed that at a working speed of 1m/s and a depth of 150mm with lower lifting and cutting angles of 25° and 45°, respectively, provide the best combination for lowering energy consumption. The soil bin tests showed that these settings provide a good soil disturbance.

Influence of pin and hammer mill on grinding characteristics, thermal and antioxidant properties of coriander powder.

In present study, influence of grinding (hammer and pin mills) and moisture content (range: 6.4-13.6% dry basis) on the quality traits of coriander powder were investigated. These include grinding parameters, colour parameters, specific heat, thermal conductivity, thermal diffusivity, glass transition temperature, essential oil, total phenolic content, total flavonoid content and DPPH scavenging (%) of coriander powder. For coriander seed, the geometric properties such as major, medium, minor dimensions, geometric mean diameter, arithmetic mean diameter, sphericity, surface area and volume of coriander seeds increased significantly with increasing moisture (6.4-13.6% db). For coriander powder, the grinding parameters such as average particle size, volume surface mean diameter and volume mean diameter increased significantly with increasing moisture (6.4-13.6% db). With the grinding method, the colour attributes of coriander powder such as L-value, a-value, b-value, hue angle and browning index varied significantly. It was observed that the specific heat followed second order polynomial relationship with temperature and moisture whereas thermal conductivity varied linearly with temperature and moisture content. The variation of glass transition temperature with moisture can be best represented in quadratic manner. Total flavonoid content (mg QE/g crude seed extract) and DPPH scavenging % activity of coriander powder is significantly affected by grinding methods. A lower value of specific heat was observed for hammer ground coriander powder as compared to pin mill ground coriander powder. The thermal conductivity of hammer mill ground coriander powder was higher as compared to pin mill ground coriander. It was observed that hammer mill yields more fine coriander powder in comparison to pin mill. The browning index was more in hammer mill ground coriander powder.

Cooperative effects and energy barriers to bromonium ion transfer in cyclic (BrX)n halogen-bonded clusters (X = F, OH, or NH2; n = 3–5): An ab initio study

Cooperative effects on the Br–X⋯Br–X halogen bond interactions present in cyclic (BrX)n clusters, (n=3–5, X=F, OH or NH2) are investigated using theoretical calculations at the B3LYP and MP2 level using the aug-cc-pvtz basis set unless indicated otherwise. Pertinent geometrical, vibrational, energetic and topological parameters are used as primary indicators of halogen bond strength, and consequently for assessment of cooperativity. Trimer formation weakens, relative to the dimer, the halogen bond interaction while formation of the larger cluster strengthens it. Cooperative enhancement of the Br⋯X halogen bond depends on X, and follows the order X=F>X=OH>X=NH2. Thus, the weakest dimer interaction exhibits the largest cooperative enhancement in these halogen bonded systems. A linear relationship is found between the average dissociation energies of the clusters with electron density at the halogen bond critical point, while a second order polynomial relationship is found between the average dissociation energies of the clusters and the average amount of charge transfer, 〈qT〉, from the acceptor X lone pairs into the antibonding Br–X orbitals, nX→σ∗Br–X. It is found that multiple Br transfer exhibits relatively high energy barriers, and follows a concerted mechanism with transition state geometries of Dnh symmetry for BrF and BrNH2 cyclic clusters, and with geometries of Cn symmetry for the transition states of the corresponding BrOH clusters.

Evolutionary factors affecting the cross-species utility of newly developed microsatellite markers in seabirds.

Microsatellite loci are ideal for testing hypotheses relating to genetic segregation at fine spatio-temporal scales. They are also conserved among closely related species, making them potentially useful for clarifying interspecific relationships between recently diverged taxa. However, mutations at primer binding sites may lead to increased nonamplification, or disruptions that may result in decreased polymorphism in nontarget species. Furthermore, high mutation rates and constraints on allele size may also with evolutionary time, promote an increase in convergently evolved allele size classes, biasing measures of interspecific genetic differentiation. Here, we used next-generation sequencing to develop microsatellite markers from a shotgun genome sequence of the sub-Antarctic seabird, the thin-billed prion (Pachyptila belcheri), that we tested for cross-species amplification in other Pachyptila and related sub-Antarctic species. We found that heterozygosity decreased and the proportion of nonamplifying loci increased with phylogenetic distance from the target species. Surprisingly, we found that species trees estimated from interspecific FST provided better approximations of mtDNA relationships among the studied species than those estimated using DC , even though FST was more affected by null alleles. We observed a significantly nonlinear second order polynomial relationship between microsatellite and mtDNA distances. We propose that the loss of linearity with increasing mtDNA distance stems from an increasing proportion of homoplastic allele size classes that are identical in state, but not identical by descent. Therefore, despite high cross-species amplification success and high polymorphism among the closely related Pachyptila species, we caution against the use of microsatellites in phylogenetic inference among distantly related taxa.

Design and Calibration of a Low Speed Wind Tunnel

A low speed, open circuit, laboratory wind tunnel was designed and built to facilitate the testing of airfoils designed for use with straight bladed vertical axis wind turbines. The wind tunnel built was the open-circuit type and was chosen due to the ease of fabrication and low construction costs associated with the build. Wind speed through the tunnel was controlled by a variable speed WEG 3.00 hp motor drive unit with a WEG CFW 08 vector inverter plus motor speed control unit. Calibration tests were performed using a hot-wire anemometer to determine the wind velocity as a function of differential pressure measured using a pressure transducer. The characteristic curve of wind velocity vs inches of water was plotted. The velocity profile for this wind tunnel indicated a turbulent flow regime and there was a good second order polynomial relationship between the measured velocity and differential pressure drop.