Second-order Relationship Research Articles

Thermosonic Flip Chip Interconnection Using Electroplated Copper Column Arrays

A novel flip chip process is reported in which bare dies are thermosonically bonded to arrays of electroplated copper columns formed on a substrate. The new process is intended as a low-cost, lead-free chip-on-board (COB) interconnection method for high-frequency devices. A detailed study has been performed of the electroplating and thermosonic bonding techniques involved. It was found that oxygen plasma treatment of the resist mask could increase the yield of the fine-pitch (<150 mum) column electroplating process, while the flatness of the resulting columns was affected by the plating current density and the sidewall profiles in the resist mold. Under optimal conditions, column arrays with flat tops could be produced with a 100% yield, and with a column height deviation of less than 0.5 mum over an area of 10 mmtimes10 mm. The array thermosonic bonding process was studied with the aid of Box-Behnken design of experiments based on response surface methodology. A second-order relationship between the input bonding variables and the bonding strength was derived and used to determine optimal process conditions. With this optimized process, silicon chips with aluminium metallization were thermosonically flip chip bonded to quartz test boards bumped with gold-capped copper columns. Sixteen prototype assemblies without underfill protection were evaluated by accelerated lifetime tests. The contact resistances of single column connections showed no significant change after 50 thermal shocks of 0 degC to 100 degC, and samples subjected to high-temperature storage remained intact at all bonding interfaces after 1.5 h at 300 degC. Thermal cycling between -55degC and 125 degC produced open-circuit defects in a small number of connections after 70 cycles

PERFORMANCE MEASUREMENT OF TENNIS EQUIPMENT

Equipment is exerting an increasing influence on the nature of tennis. The International Tennis Federation (ITF) Technical Centre was set up to ensure that the challenge and identity of the game is retained, while not discouraging technological innovation. As the physiological characteristics of the player are not under its control, the Technical Centre must pursue its mission through the understanding and control of equipment. This requires systematic testing to establish its characteristics, and research and development projects to identify methods of measuring those characteristics that are not currently covered by the Rules of Tennis. This paper describes tests, test methods and current research programs that the ITF has devised to measure the performance of tennis equipment. Although tennis balls are currently tested for size, mass, compression and rebound, two further variables are being researched to more fully specify its characteristics: dynamic coefficient of restitution and aerodynamics (lift and drag). The former project has suggested an inverse second-order relationship between coefficient of restitution and impact speed. A racket performance machine is described, which is designed to replicate the impact characteristics of tennis serves, and which will be used to benchmark the performance characteristics of tennis rackets. Initial results demonstrate the relationship between "power" and both impact speed and impact location. Surfaces, too, play an important role in determining ball rebound characteristics. A test that measures the frictional interaction between the ball and surface during impact, which is converted to a measure of surface "space" is described. The results of these projects will allow the ITF, in its role as guardian of the game, to make informed decisions on the rules relating to equipment, and help ensure that tennis retains its identity.

Preweaning piglet mortality in relation to placental efficiency1

The relationship between placental efficiency (PLEFF, i.e., the ratio of birth weight [BWB] to placental weight [PLW]) and neonatal pig vitality as measured by the probability of preweaning death of live born piglets was examined for 1,036 live born piglets of 118 litters. The data were first analyzed to establish whether the relationships between PLEFF, PLW, and BWB were affected by parity (first vs. higher). Furthermore, the data collected were used to establish whether PLEFF is a better predictor of the risk of neonatal pig mortality before weaning than BWB and PLW. The relationships of BWB to PLW and PLEFF to PLW differed (P <0.01 and P <0.05, respectively) between piglets from gilts and sows. This difference appeared to be due mainly to an additional population of piglets with very large placentas in sows that were not present in gilts. Despite being significant, the courses of the relationships were essentially similar for piglets in gilts and in sows. For the curvilinear relationship of BWB to PLW, up to a certain threshold value, an increase of PLW resulted in an increase in BWB, and thereafter BWB did not change. A consequence of this is that PLEFF at relatively high PLW does not give the same information as PLEFF at relatively low PLW. For the second-order relationship of PLEFF to BWB, PLEFF increased with an increase in BWB, until BWB = 1,657 g, and decreased thereafter. The PLEFF decreased linearly with PLW. A change in PLW had a much larger impact on the value of PLEFF than a change in BWB. Although BWB and PLW were negatively associated with the chance of dying before weaning (P <0.001 and P <0.01, respectively), only PLEFF tended to be negatively associated with the chance of dying only before weaning (P = 0.08). Its underlying trait, BWB, played a greater role on the effect of PLEFF on the chance of preweaning death than PLW. In conclusion, PLEFF in swine is a complicated trait that should be treated with care. It is merely a mathematical derivative of BWB and PLW, whereby the extent to which BWB depends on PLW depends on the value of PLW. Placental functioning and fetal growth capacity, however, also have their effects on the value of BWB. It is concluded that, of the three traits (BWB, PLW, and PLEFF), the best predictor for the chance of preweaning mortality, which also happens to be easiest to measure, remains BWB.

Rod‐climbing characteristics of α‐Fe2O3 suspended polyisobutylene/polybutene solution

AbstractFrom rod‐climbing rheometer measurements, we systematically investigated the normal stress values of suspended particles in polymeric liquids at low shear rates using the second‐order fluid constitutional relationship. The climbing constants β of the suspended α‐Fe2O3 particles in polyisobutylene/polybutene solutions, which exhibit Boger fluid characteristics (highly elastic, but no shear‐thinning), were estimated from the rod‐climbing experiment, showing that β increased with polymer concentration and polymer molecular weight. The first normal stress difference coefficient of the suspended α‐Fe2O3 in polymeric liquids obtained from the rod‐climbing rheometer was well correlated with the rheological properties measured by rotational rheometers. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1548–1552, 2004

Functional Differential Equations in Sustainable Forest Harvesting

This article deals with the dynamics of the volume control method in forest regulation. The sustainability of harvesting a given constant volume in a simplified forest model is studied. Depending on the initial age distribution, the cut can lead to the forest exhaustion, or to an asymptotic steady-state uniform age distribution. A continuous model is formulated in terms of various kinds of partial differential equations, delay differential equations, and non-linear integral equations. Equilibrium solutions and their stability properties are determined. Discrete models are also obtained, both by direct reasoning and as approximations to the continuous case. These are used for simulation and graphical exploration of the system behavior. In addition, contrasting various discrete and continuous versions was found useful in clarifying some issues, in particular, ambiguity/redundancy problems in the relation between integral equations and delay differential equations derived from them. The basic problem of evaluating sustainability for an initial distribution remains unsolved, however. Further progress is linked to the asymptotic properties of a second-order recurrence relationship. It is hoped that the interplay between the theory of functional differential equations and this concrete and easily interpretable problem in forest management might prove fruitful in both fields.

Tube-sample coupling in XRF spectrometry

The introduction of the latest generation of wavelength-dispersive XRF spectrometers, with closely coupled x-ray tube-to-sample optics, has led to significantly higher x-ray intensities, lower detection limits and shorter counting times for the same level of precision. The higher intensities result from the inverse square law relationship between decreasing distance and the exponential increase in x-ray flux. However, with decreasing distance, small errors (e.g. ±100 µm) in sample positioning with respect to the sample datum height will lead to intensity errors which should be similarly magnified by the inverse square law. Such small positioning errors can in theory lead to intensity errors exceeding ±1% in closely coupled spectrometers. However, intensity measurements on height-adjustable test samples show that for inclined tube spectrometers (side-window and end-window sequential), the inverse square law is not followed. Observed intensity variations with small changes in sample height were much less than expected from the inverse square law. Instead the measured intensities follow a second-order parabolic relationship. For some spectrometers the crest of this parabola is close to the sample datum height and intensity variations are greatly reduced (i.e. <0.1% per ±100 µm). The parabolic relationship is considered to reflect (i) the asymmetric distribution of the primary x-ray flux on the sample and (ii) the restricted collimator field-of-view (product of collimator mask size and take-off angle). The interaction between these factors leads to compensating effects that buffer the measured x-ray intensities against changes in sample height. By contrast, in end-window simultaneous spectrometers the measured intensities indicate conformance to the inverse square law with important implications for analytical errors. Copyright © 2000 John Wiley & Sons, Ltd.

Structure–Second-Order Polarizability Relationship in Chromophores

Structure–Second-Order Polarizability Relationship in Chromophores

Optimizing the Mechanical Strength of Fe-Based Commercial High-Temperature Water−Gas Shift Catalyst in a Reduction Process

It has been elaborated that reduction is one of the key processes for the mechanical reliability of an iron-based high-temperature water−gas shift catalyst. The process factors such as the heating rate, the reduction temperature, and the steam to gas ratio all have strong effects on the mechanical strength of the catalyst. For the catalyst pelletized in a laboratory, it has been observed that the mean value and the reliability of the mechanical strength can be increased much at suitable conditions, while under some conditions still often employed industrially these can be decreased much compared to the oxidized state. In the experiments, the best sample gains 37.3% and the worst loses 24.7% of the mean strength. In the same set of experiments with a narrow range of variation of the factors, the probability of strength failure of the best sample at 10 kg/pellet is 8 orders of magnitude lower than that of the worst. The analysis shows that the factors mentioned and the mean strength can be regressed by a second-order relationship. The temperature-programmed reduction and magnetic susceptibility measurements reveal that the ferromagnetic property of the reduced samples contributes a lot to the increase of the mean strength. The experiments with a commercial catalyst at several conditions also show a decisive effect of the factors on its mechanical reliability. It is plausible that the catalyst has different mechanical reliability in different positions in the industrial converters after reduction.

Growth hormone-binding proteins during human pregnancy: maternal, fetal and neonatal data.

Serum levels of growth hormone-binding protein (GHBP) were measured by high-performance liquid chromatography (HPLC) gel filtration in serum of 30 pregnant women and in cord serum of 69 preterm and term infants. In pregnant women, the mean +/- SD serum level of GHBP was 32.4% +/- 5.6%. Polynomial regression analysis showed a significant (P = 0.01) second-order relationship between the duration of pregnancy and serum GHBP levels, with increasing levels during the first half of pregnancy and decreasing levels thereafter. In cord serum, the mean +/- SD serum level of GHBP was 3.1% +/- 1.4% (n = 51) in preterm and 4.2% +/- 1.3% (n = 18) in term neonates. Serum GHBP concentrations were related to gestational age (r = 0.35; P < 0.005) and to intrauterine nutritional state as evaluated by the ponderal index (r = 0.30; P < 0.02). In four term neonates, serum levels of GHBP were measured before and after an exchange transfusion (ET). Before the ET the serum GHBP level was 6.7% +/- 2.4% and at the end it was 25.3% +/- 2.6%. Thereafter, serum GHBP levels decreased slowly. Analysis of the elimination curve by exponential stripping showed a biexponential elimination pattern: GHBP (%) = 40.e(-5.1E-03 x time) + 64.e(-2.5E-04 x time). The serum half-life of the GHBP complex was estimated to be about 2 days.

Effect of oestrogen status on serum levels of growth hormone‐binding protein and insulin‐like growth factor‐I in non‐pregnant and pregnant women

Since there appears to be a relationship between circulating oestrogens and growth hormone, we have investigated the effect of the oestrogen status of adult women on serum levels of GHBP and IGF-I. The investigation was performed on serum samples of 14 spontaneously menstruating women, 10 women taking oral contraceptives containing 20-50 micrograms ethinyloestradiol, and 30 pregnant women at different stages of pregnancy. Serum levels of GHBP were measured by HPLC gel filtration and IGF-I levels were measured by RIA after acid-ethanol extraction. In the spontaneously menstruating women the mean +/- SD serum level of GHBP was 34.6 +/- 6.7% and of IGF-I 30 +/- 7 nmol/l. Serum GHBP levels were negatively (r = -0.67; P < 0.01) and IGF-I levels were positively related (r = 0.69; P < 0.01) to serum oestradiol concentrations. In the women taking oral contraceptives serum levels of GHBP were 47.0 +/- 7.4%. This was significantly (P < 0.001) higher than in spontaneously menstruating women. In contrast, IGF-I levels were not different from those obtained in spontaneously menstruating women. In the pregnant women, the mean +/- SD serum level of GHBP was not different from that observed in non-pregnant spontaneously menstruating women. Polynomial regression analysis, however, showed a significant (P = 0.01) second-order relationship between the duration of pregnancy and serum GHBP levels, with increasing levels during the first half of pregnancy and decreasing levels thereafter. Serum concentrations of IGF-I increased during the second half of pregnancy and were significantly (P < 0.005) elevated in the third trimester. In non-pregnant women the endogenous oestrogen status seems to modulate negatively GHBP levels and positively IGF-I levels, whereas oral oestrogen administration, in contrast, increases serum levels of GHBP without modification of IGF-I levels. During pregnancy serum GHBP levels increase slightly during the first half of pregnancy and decrease thereafter, whereas IGF-I concentrations increase during the second part of pregnancy. The oestrogen status of women has a complex effect on serum concentrations of GHBP and IGF-I and has therefore to be taken into account when evaluating serum levels of GHBP and IGF-I.

Detection of some sulphur anions and colloidal sulphur by flame molecular emission spectrometry

A simple flow-injection method was used to compare the disulphur emission from sulphite, thiosulphate, sulphide, thiocyanate, diethyldithiocarbamate and colloidal sulphur with that of sulphate. Counter ions were replaced with hydronium through the use of an in-line ion-exchange column. All the compounds conformed to the second-order calibration relationship already established for sulphate, but with higher emission efficiencies. The estimated detection limits range from 0.1 to 0.8 mg s l −1. The effect on the emission efficiencies of decomposition of the sulphur acids was investigated by comparison with the corresponding ammonium forms. Ammonium ions enhance the disulphur emission, in contrast to the well established depressive interference from metal cations.

Quantitation of thin-layer chromatograms with an Apple II computer-based videodensitometer

An inexpensive, high-speed densitometer made from an Apple II computer, a black-and-white video camera, and an image digitizing board is described. By supplementing the computer with a very fast coprocessor, one can obtain a measurement of a typical thin-layer spot in 30–40 s. Only minimal electronic expertise is required for assembling the system from the commercially available components. Coefficients of variation for multiple readings of a single 500-ng spot of charred lipid were about 0.5%. For lipid spots weighing 250 to 2000 ng, a second-order relationship between weight and density reading was obtained with a correlation coefficient of 0.998.

Decomposition of .alpha.-aluminum hydride powder. 2. Photolytic decomposition

Similarly shaped pressure vs time curves are obtained in the temperature range from 26 to 70.6/sup 0/C from the ultraviolet photolysis of aged ..cap alpha..-AlH/sub 3/ powder, pristine and preirradiated with /sup 60/Co ..gamma..-rays. The curves consist of an initial deceleratory period followed by a constant rate of gas evolution. The initial-period data can be resolved into one or two exponential terms depending on the sample and/or the pretreatment conditions. At room temperature, increasing the light intensity or preirradiating the material with ..gamma..-ray doses greater than 1.0 x 10/sup 6/R increases the rate constants obtained from fitting the kinetic data. Only one exponential term is found below 1.0 x 10/sup 6/R and at high lamp intensities. The linear rate has an almost, but not exact, second-order dependence on the light intensity. The dependence is ascribed to a decomposition event resulting from interaction between two excited radicals, one of which forms a radical-hole pair prior to the interaction. The linear rate deviates further from a second-order dependence for a 1.0 x 10/sup 6/R dose. The activation energies (kJ/mol) of the initial and linear rate periods are 3.2 (+- 0.9) and 13.0 (+- 0.9), respectively. Taken together these results suggest that twomore » processes are initiated by uv light in ..cap alpha..-AlH/sub 3/. The first process involves the interaction of the light-induced carriers with the precursor (intrinsic) defects exising in the material. This process is associated with the lower activation energy. The second process with the larger activation energy is the interaction of the light-induced carriers with each other to produce decomposition in a complex second-order relationship. Both processes are modified by irradiation in a manner consistent with a previously developed phenomenological theory. 5 figures.« less

A study of the interactions between glutamate and aspartate at the lobster neuromuscular junction.

The depolarization produced by bath-applied or iontophoretically applied glutamate and aspartate were recorded from lobster muscle fibres by means of intracellular microelectrodes. 2 Bath-applied glutamate or aspartate evoked reversible, membrane depolarizations; however, responses to repeated applications of aspartate decreased progressively in amplitude until a plateau level was attained. Repeated applications of glutamate, kainate, domoate or quisqualate did not produce a similar effect. 3 After a dose of glutamate, responses to bath-applied aspartate were enhanced. Responses to other depolarizing agonists were little affected by previous administration of glutamate. Aspartate dose-depolarization curves were therefore constructed after initial aspartate responses had stabilized. The log-log transforms of the aspartate and glutamate curves had limiting slopes of 0.8 and 2.1 respectively. 4 Iontophoretic application of aspartate to single glutamate-sensitive sites produced small depolarizations with slow time course, compared with the glutamate potentials. When aspartate and glutamate were pulsed simultaneously from a twin-barrelled pipette, the resultant glutamate potential was enhanced. It is suggested that this potentiation was due to summation of agonist concentrations in the receptor region interacting with a second-order dose-response relationship. 5 Bath-applied aspartate increased the amplitude and prolonged the half-decay time of the glutamate potential. This effect was particularly noticeable when the glutamate potential was of slow time course. 6 It is proposed that bath-applied aspartate has an agonist effect whose magnitude is possibly exaggerated by concomitant release of glutamate and/or inhibition by glutamate of aspartate uptake. This agonist action of aspartate is thought to be exerted mainly on extrajunctional areas of the glutamate-sensitive sites.

Determination of the binding constant of ligand to protein by thermal inactivation technique: Effect of two binding sites

Theoretical considerations on the determining the binding constants (π) of ligands to proteins were carried out. Whereas for a one-subunit protein the relationship between thermal inactivation rates and ligand concentration there is a simple linear function, for a protein with two subunits, a second-order relationship is derived. If the theory for one-subunit proteins is applied to multi-subunit proteins, the derived values of π tend to be lower than the real binding constants. A method of determining the ligand binding constant for a two-subunit protein is described.

Note on shock-wave velocity in high-speed liquid-solid impact

A better relationship between the shock-wave and impact velocities in high-speed water-solid impact is determined from the fundamental equations of continuity, momentum, and state. A second-order relationship is hypothesized and the necessary coefficients then found using the Tait equation of state. Very good agreement is found with available experimental data for water.

An Exploratory Study of Taylor’s Tool-Life Equation by Power Transformations

Transformations of both dependent and independent variables are employed to investigate the linearization of Taylor’s tool-life equation. This exploratory study indicates that a logarithmic transformation, which is a special case of the general class of power transformations, gives the best fit for HSS tool-life data. However, the study does not show that a logarithmic transformation is the best for carbide tool-life data. For a wide cutting range, where Taylor’s tool-life equation does not hold, a linear equation instead of a second-order relationship for the prediction of tool life can be determined by the proper transformation.