bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of Test Methods for Dynamic Toughness Characterization of Duplex Stainless Steel Forgings
Authors: Natishan ME , Tregoning RL
Published: March 2009

Ferralium is a dual-phase stainless steel which consists of roughly equal amounts of ferrite and austenite. Conventional Charpy V-notch impact tests were performed on specimens taken from several locations in three orientations from a forged Ferralium plate to quantify the materials dynamic fracture performance. The Charpy tests were compared with 2.54 cm thick (1T) single edge bend (SE(B)) specimens that were tested in a drop tower to measure dynamic fracture initiation toughness (KId). SE(B) specimens were removed from three plate locations and tested in a single orientation. Charpy and KId tests were performed over the entire fracture mode transition temperature range, but the bulk of testing was concentrated at a single temperature \t-2‡C to provide a statistically significant number of tests at a representative point in the ferritic fracture mode transition region. Charpy impact energy varied consistently with both orientation and location within the forged plate even though large scatter was present in the results. This large scatter precluded an accurate assessment of the materials fracture performance within the transition region. The scatter in the drop tower (SE(B)) results was much less and indicated that plate location had a minimal affect on performance. The reduced scatter in the SE(B) specimens is attributed to two factors. First, the microstructure of Ferralium, while macroscopically homogeneous, contains ferritic and austenitic phase sizes that approach the dimensions of the standard Charpy specimen. Second, the Charpy testing technique causes more variation than the standard SE(B) KId tests within the transition region.
Fracture Toughness and Critical Crack Sizes for the Space Shuttle Solid Rocket Motor D6AC Steel Case
Authors: Newman JC , Bland JD , Berry RF
Published: March 2009

Fracture toughness and critical crack size tests were conducted on a variety of fracture specimens that were machined from actual Space Shuttle solid rocket motor (SRM) D6AC steel cylindrical case segments. Plane-strain fracture toughness tests were conducted at four temperatures ranging from −30‡C to 55‡C. Average values ranged from a low of 87.6 MPa-m1/2 at −30 ‡C to a high of 120.3 MPa-m1/2 at room temperature. Fracture tests were also conducted on seven different crack configurations that simulate details in the SRM field and factory joint locations. These configurations included: surface and through cracks, corner and through cracks at an open hole, and through and corner cracks at a pin-loaded hole. Elastic stress-intensity factors at failure, KIe, were found to be constant within ± 10% for the range of crack and specimen sizes tested. The fatigue pre-cracking stress levels were found to have a strong influence on KIe. An effective elastic fracture toughness, accounting for crack-closure effects, was found to be nearly constant for a wide range of fatigue pre-cracking stress-intensity factor levels.

Fatigue tests were also conducted on simulated SRM case-segment joint leak-check port specimens to determine crack initiation locations, fatigue-crack growth and critical crack sizes. Eddy-current probes, identical to those used in actual hardware, were used to monitor crack growth. Specimens were cycled at either proof-test load or flight-load levels at various temperatures until failure. Critical crack sizes obtained were greater than 25 mm in length and required more than 2,700 cycles to grow from a damage-tolerant crack size (1 mm) to failure.
Effect of Beryllium on the Burn Propensity of Titanium Alloys
Authors: Schmees RM
Published: March 2009

The burn characteristics of titanium alloy systems have limited their usefulness in environments that are typical during normal aircraft gas turbine engine operation. The density advantages of replacing nickel base superalloys would result in superior performance, fuel burn, and pay load. A novel approach to increasing burn resistance was based on reducing the alloy liquidus temperature below the temperature where catastrophic oxidation occurs. Beryllium was chosen as an alloying agent to titanium base alloys because of its ability to depress the liquidus temperature. Emphasis was made to evaluate burn characteristics in a compressor type environment. To improve burn resistance over baseline alloys a beryllium content between 10 and 18 atomic percent is required.
Cone Calorimeter Testing of Epoxy/Fiberglass and Broninated Epoxy/Fiberglass Composites in Normal Oxygen and Oxygen-Enriched Environments
Authors: Hshieh F-Y , Beeson HD
Published: March 2009

A controlled-atmosphere cone calorimeter was used to investigate the burning of one epoxy/fiberglass and two brominated epoxy/fiberglass composites. The composites were tested in normal oxygen and oxygen-enriched environments (oxygen concentration up to 30 percent) at 25, 35, and 50 kw/m2 heat fluxes. Results indicate that the heat flux had a major effect on the ignitability of epoxy/fiberglass and brominated epoxy/fiberglass while the oxygen concentration had a minor effect. The ignitability of epoxy/fiberglass was similar to that of brominated epoxy/fiberglass except the critical heat flux for ignition. For epoxy/fiberglass, the peak mass loss rate, peak heat release rate, and total heat released increased with the increase of oxygen concentration and heat flux, and the average specific extinction area decreased with the increase of oxygen concentration and heat flux. For brominated epoxy/fiberglass, the peak heat release rate and total heat released increased with the increase of oxygen concentration. In comparison with epoxy/fiberglass, brominated epoxy/fiberglass self-extinguishes faster, and produces more carbon monoxide (CO) and less carbon dioxide (CO2) during burning. The upward flame spread rate and upward flame spread length of each composite obtained in separate experiments can be correlated with the peak heat release rate data obtained from the cone calorimeter tests. The controlled-atmosphere cone calorimeter was effective in differentiating the burning of epoxy/fiberglass and brominated epoxy/fiberglass and is an effective tool for selecting materials to be used in the oxygen-enriched environments.
A Protocol for Evaluating the Cleaning Efficiency, Corrosion Property and Oxygen Compatibility of Non-Ozone Depleting Cleaning Agents
Authors: Chou TC , Fiedorowicz A
Published: March 2009

A comprehensive protocol was developed and practiced to evaluate the suitability of non-ozone depleting degreasers for oxygen cleaning applications. Of particular concern in the protocol were methodologies employed to examine the specific properties, including cleaning effectiveness factor, non-volatile residue, chemical compatibility and oxygen compatibility, of various degreasing agents. Using this protocol, a number of cleaning agents including aqueous degreasers, chlorinated solvents, terpenes and hydrocarbons were evaluated for oxygen service. As baseline information, 1,1,1-trichloroethane and D.I. water were also evaluated and their properties compared with those of the non-ozone depleting degreasers. According to the evaluation results, solvent-type degreasers generally exhibited better performance than aqueous-type degreasers in cleaning property, corrosion property and oxygen compatibility property. D.I. water at 160°F was found to yield unsatisfactory cleaning efficiency even with the aid of ultrasonic agitation. Among the solvent degreasers evaluated, chlorinated solvents including trichloroethylene and methylene chloride were shown to possess the best properties. Depending upon individual's needs and the type of degreaser to be selected, this protocol can be adopted in part or in full to evaluate the suitability of a degreaser for oxygen cleaning.
Use of Mussels and Semipermeable Membrane Devices to Assess Bioavailability of Residual Polynuclear Aromatic Hydrocarbons Three Years After the Exxon Valdez Oil Spill
Authors: Shigenaka G , Henry CB
Published: March 2009

Mussels (Mytilus cf. trossulus) were transplanted to a heavily oiled and extensively treated site on Smith Island, Prince William Sound, Alaska, in 1992. A new monitoring and assessment tool, the semipermeable membrane device, was also deployed to compare hydrocarbon uptake with mussels and to evaluate the route of exposure to mussels. Both mussels and semipermeable membrane devices accumulated polynuclear aromatic hydrocarbons during 14- and 52-day deployments, particularly at the oiled site. Accumulation levels were similar between mussels and the semipermeable membrane devices, but the distribution of individual hydrocarbons differed. The results permit some inference about route of exposure to mussels. Sheens leaching from subsurface deposits of residual oil, and particulate material with adsorbed hydrocarbons were apparently more important exposure pathways than dissolved hydrocarbons in water. Semipermeable membrane devices show promise as monitoring tools and to provide insights into exposure pathways for biota.
Use of Oil-Affected Habitats by Birds After theExxon ValdezOil Spill
Authors: Day RH , Murphy SM , Wiens JA , Hayward GD , Harner EJ , Smith LN
Published: March 2009

This study investigated the effects of the Exxon Valdez oil spill on the use of oil-affected habitats by birds during 1989–1991. We measured densities of birds in bays that had been subjected to various levels of oiling from the spill during survey cruises that were conducted throughout the year in Prince William Sound (PWS) and during summer along the Kenai Peninsula. Overall, 23 of 42 (55%) species in PWS and 22 of 34 (65%) species on the Kenai showed no evidence of oiling impacts on their use of habitats. Most species that did show initial negative impacts had recovered by late summer 1991 when our study concluded, although 6 of the 19 species initially impacted in PWS and 6 of the 12 species initially impacted along the Kenai did not exhibit clear signs of recovery by this time. A Principal Components Analysis of species examined from PWS revealed extensive overlap in ecological attributes among species that were and were not negatively impacted in their use of oil-affected habitats. Species that did not show clear evidence of recovery tended to be intertidal feeders and residents of PWS, but other ecologically similar species evidenced either no initial impacts or rapid recovery. These similarities suggest that the prognosis is good for the species for which we were unable to document recovery in habitat use. Our findings, together with the rapid rates of recovery in habitat features reported in other studies, suggest that impacts of the Exxon Valdez oil spill on avian use of oil-affected habitats generally were not persistent.
Density and Productivity of Bald Eagles in Prince William Sound, Alaska, After the Exxon Valdez Oil Spill
Authors: White CM , Ritchie RJ , Cooper BA
Published: March 2009

Helicopter surveys were conducted in Prince William Sound (PWS) to assess the effects of the 1989 Exxon Valdez oil spill on the reproductive success and densities of bald eagles (Haliaeetus leucocephalus) one and two years after the spill (1990 and 1991). Densities of bald eagles were compared between an oiled area in southwestern PWS and an unoiled area in northern PWS. In all surveys (four in 1990, one in 1991) densities of eagles in the oiled area generally were similar to or higher than those in the unoiled area. Reproductive success was compared between nesting territories that were oiled within 1 km of nests and nesting territories that were unoiled. In 1990, all measures of nest productivity, nest occupancy, and nesting success were similar between oiled and unoiled territories. In 1991, however, the number of young per successful nest was lower in oiled territories. The number of successful nests was slightly lower in 1991 than in 1990 in oiled territories but was significantly lower in 1991 in unoiled territories. Comparisons of nest occupancy and nesting success could not be made in 1991 because early surveys were not conducted. Differences between areas, territories, and years could not be attributed to oil, but rather appeared to be related to natural annual variability. Overall, no demonstrable effects of the oil spill on eagle density or reproduction could be detected in PWS one and two years after the spill.
Common Murre Abundance, Phenology, and Productivity on the Barren Islands, Alaska: The Exxon Valdez Oil Spill and Long-Term Environmental Change
Authors: Boersma PD , Parrish JK , Kettle AB
Published: March 2009

The Exxon Valdez oil spill in 1989 caused substantial seabird mortality. By 1 August, more than 30 000 seabird carcasses (74% murres) were recovered, and it was initially estimated that between 100 000 and 300 000 seabirds were killed. The Barren Islands, in particular East Amatuli Island, support the largest seabird colonies within the path of the spill. With respect to murres nesting on the Barren Islands, claims were made that the population suffered at least a 50% loss and that the remaining population underwent a change in breeding phenology, a breakdown in breeding synchrony, and a widespread failure to fledge chicks in the years following the spill. As a result of these effects, it was projected that the population would take 20–70 years to recover.

Principally because of the paucity of prespill data on the Barren Islands murre population size and reproductive success, it is impossible to quantify any effect of the spill on these populations. Available prespill data (1976–1978) on the East Amatuli murre population size ranges from 19 000 to 61 000 birds. These data are not systematic, replicated counts but rather are estimates indicating a broad range within which the true attendance figure probably resided. Our postspill attendance counts range from 31 041 to 37 128 (1990–1992). Comparisons between matched historical and 1990s photographs showed nearly identical attendance patterns, although there were significantly more murres in the 1990s photographs. Postspill attendance data from multiply censused areas suggest a recovery may have been taking place because of greater than expected annual increases (+25% from 1990 to 1991).

Prespill data on reproductive activity of the murres nesting in the Barren Islands were collected from a single 5 × 5-m plot located in a dense, flat section of the East Amatuli Light Rock colony. Comparisons with similarly collected postspill data suggest that phenology, egg production, and chick production are extremely variable among years, athough chicks were fledged in all years. Egg and chick production were highest in 1977 and 1991 and lowest in 1992.

On the basis of these analyses, we conclude that, although murres rafting near the Barren Islands undoubtedly suffered substantial mortality as a result of the Exxon Valdez oil spill, there is no justification for claims of either a dramatic reduction in colony attendance or substantial failure of the remaining birds to settle and reproduce, in the years following the spill. In spite of continued perturbations to the system from both natural and human-induced sources, East Amatuli Island continues to support a large, reproductively active colony of murres.
Elektromechanischer Energiewandler auf Basis eines piezokeramischen BiegebalkensElectromechanical Energy Harvester Based on a Piezoceramic Bending Cantilever
Authors: Albach Thorsten , Sutor A. , Lerch Reinhard
Published: March 2009

Es wird ein elektromechanischer Energiewandler vorgestellt, der auf dem piezoelektrischen Wandlungsprinzip in Form eines Biegebalkens beruht. Er wandelt Umgebungs-Vibrationen in elektrische Energie. Ausgehend vom bekannten Aufbau mit konstantem Balkenquerschnitt wird der Energieertrag durch Modifikation des Balkenprofiles erhöht. Im Hinblick auf eine praktische Realisierbarkeit wird die analytisch gefundene optimale Geometrie durch ein lineares Profil approximiert. Die Ergebnisse werden mittels einer Finite-Elemente-Simulation verifiziert. Am Beispiel einer Vakuumpumpe als Schwingungserreger wird die Funktionsfähigkeit des Wandlers demonstriert. Es kann eine Leistung von 15mW und eine Leistungsdichte von 670W/m3 bei ohmscher Beschaltung erreicht werden. Eine selbstversorgende Elektronik wandelt die gewonnene Wechselspannung auf ein stabiles -3V-Potenzial.
Development of cloned embryos from porcine neural stem cells and amniotic fluid-derived stem cells transfected with enhanced green fluorescence protein gene
Authors: Zheng Yue-Mao , Zhao Hui-Ying , Zhao Xiao-E , Quan Fu-Sheng , Hua Song , He Xiao-Ying , Liu Jun , He Xiao-Ning , Lin Hui
Published: March 2009

We assessed the developmental ability of embryos cloned from porcine neural stem (NS) cells, amniotic fluid-derived stem (AFS) cells, fetal fibroblast cells, adult fibroblast, and mammary gland epithelial cells. The five cell lines were transfected with enhanced green fluorescence protein gene respectively using lipofection. NS and AFS cells were induced to differentiatein vitro. Stem cells and their differentiated cells were harvested for analysis of the markers using RT-PCR. The five cell lines were used for nuclear transfer. The two-cell stage-cloned embryos derived from each cell line were transferred into the oviducts of surrogate mothers. The results showed that both NS and AFS cells expressed POU5F1, THY1 and SOX2, and they were both induced to differentiate into astrocyte (GFAP+), oligodendrocyte (GalC+), neuron (NF+, ENO2+, and MAP2+), adipocyte (LPL+and PPARG-D+), osteoblast (osteonectin+and osteocalcin+), myocyte (MYF6+and MYOD+), and endothelium (PECAM1+, CD34+, CDH5+, and NOS3+) respectively. Seven cloned fetuses (28 days and 32 days) derived from stem cells were obtained. Thein vitrodevelopmental ability (morula–blastocyst rate was 28.26–30.07%) andin vivodevelopmental ability (pregnancy rate were 1.67–2.17%) of the embryos cloned from stem cells were higher (P<0.05) than that of the embryos cloned from somatic cells (morula–blastocyst rate was 16.27–19.28% and pregnancy rate was 0.00%), which suggests that the undifferentiated state of the donor cells increases cloning efficiency.
Studies of granulosa cell maturation in dominant and subordinate bovine follicles: novel extracellular matrix focimatrix is co-ordinately regulated with cholesterol side-chain cleavage CYP11A1
Authors: Irving-Rodgers H F , Harland M L , Sullivan T R , Rodgers R J
Published: March 2009

During growth of antral ovarian follicles granulosa cells first become associated with a novel type of extracellular matrix, focimatrix, and at larger sizes follicles become either subordinate or dominant. To examine this, bovine subordinate (9.0±s.e.m.0.4 mm;n=16), partially dominant (12.0±0.6 mm;n=18) and fully dominant (15.0±0.4 mm;n=14) follicles were examined by real time RT-PCR analyses of granulosa cells and by immunohistochemistry of focimatrix. Changes in the expression of FSH receptor, LH receptor, cholesterol side-chain cleavage (CYP11A1), 3β-hydroxysteroid dehydrogenase, aromatase (CYP19A1) and inhibin-α and β-B were observed as expected for follicle sizes examined. After adjusting for size differences, onlyCYP11A1was significantly different between the groups, and elevated in dominant follicles. Also after adjusting for differences in size there were no significant differences in expression of focimatrix components collagen type IV α-1 (COL4A1), laminin β-2, nidogen 1 (NID1), and perlecan (HSPG2) or the volume density of NID1 and -2 and HSPG2. The volume density of focimatrix components in laminin 111 was significantly elevated in dominant follicles. Adjusting for analysis of more than one follicle per animal and for multiple correlations,CYP11A1mRNA levels were highly correlated with the focimatrix genesCOL4A1,NID1and -2andHSPG2. Thus, focimatrix may potentially regulateCYP11A1expression, and the regulation of both could be important in follicular dominance.
Time-resolved combined SAXS and WAXS studies on hydrating tricalcium silicate and cement
Authors: Häußler F. , Tritthart J. , Amenitsch H. , Laggner P.
Published: March 2009

The objective of the experiments discussed here was to investigate the hydration process of the clinker minerals tricalcium silicate (C3S) and tricalcium aluminate (C3A) as well as that of ordinary Portland cement in the early stage of hydration (within several hours after the onset of hydration). Small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS) patterns caused by microstructural objects (nanometre and micrometre range) as well as by crystalline phases were observed at room temperature and at 40°C. Combined and time-resolved SAXS and WAXS studies in the early stage of hydration (until approximately 21 h) are reported. The experimental results indicate that two types of internal surfaces occurred simultaneously. Smooth surfaces, namely surfaces of Euclidean geometry, coexist with fractal surfaces. Analysis of different segments of a scattering curve showed that the proportions between Euclidean and fractal surfaces changed with time after the onset of hydration. A direct comparison of the structure-forming processes in the nanometre range at different temperatures (room temperature and 40°C) is given by the SAXS results. SAXS/WAXS, in addition to small-angle neutron scattering, represents one of the few relevant non-destructive test methods that provide undisturbed information about the nanostructure and microstructure of hydrating phases. The combination of SAXS and WAXS is a powerful tool for the simultaneous observation of X-ray amorphous (non-crystalline) and crystalline structures.
Simulation of concrete slump using neural networks
Authors: Yeh I.-C.
Published: March 2009

In this study, an artificial neural network-based modelling system was established to explore the feasibility of predicting the slump of concrete. Computational simulation of concrete slump was performed using the trained neural network. The variation in concrete slump was achieved by varying combinations of factors like the water-to-binder ratio (w/b), superplasticiser-to-binder ratio (SP/B), and water content. From the graphs of water content plotted against the slump generated using the trained neural networks developed in this study, two sets of graphs were produced to explore the effects of w/b and SP/B. It was found that: (a) the use of neural networks for the modelling of concrete slump appeared very promising; (b) although the water content and SP/B ratio were kept constant, a change in w/b ratio had a distinct effect on the consistency properties; (c) a certain saturation level for the SP existed, above which only a small effect of further dispersion was obtained; and (d) a certain saturation level for the water content existed, above which only a small effect, even a negative effect, on slump was obtained.
Shear viscosity of clays using the fall cone test
Authors: MAHAJAN S.P. , BUDHU M.
Published: March 2009

A knowledge of shear viscosity is important in understanding the viscous resistance in the dynamic penetration of soils for geotechnical applications such as jacked piles and cone penetrometers. Viscosities of soils with water contents greater than the liquid limit have been investigated using viscometers. There is, however, no standard method to determine shear viscosities of clays at water contents lower than the liquid limit. In this paper, the post failure (critical state) response of fine-grained soils is modelled as if they were visco-plastic fluids. In addition, the theory of the fall cone test, currently used to interpret the index and strength properties of fine-grained soils, is re-evaluated to discern the viscous drag as the cone penetrates the soil. This re-evaluation shows that the shear viscosities of clays at liquidity indices less than 1·5 can be estimated from a continuous record of time-cone penetration depth data. Fall cone test results on kaolin show that the shear viscosity decreases exponentially with increase in liquidity indices.
Use of a genetic algorithm to perform reliability analysis of unsaturated soil slopes
Authors: GAVIN K. , XUE J.
Published: March 2009

This paper describes the development of a probabilistic design approach to analyse the stability of unsaturated soil slopes. Instability of unsaturated soil slopes is caused by the downwards progression of a wetting front, which reduces the near-surface suctions, increases the weight of soil in the failure zone and reduces the soil strength. Assuming the slip surface forms parallel to the slope surface (at a depth equal to the wetting front depth) the probability of failure is determined in this paper through the reliability index determined using a computationally efficient genetic algorithm method.
Analysis of the influence of material parameters on electrical conductivity of cement pastes and concretes
Authors: Manchiryal R.K. , Neithalath N.
Published: March 2009

This paper reports investigations on the influence of material parameters on electrical conductivity of cement pastes and concrete mixtures. The influence of cement type, water/cementitious materials ratio (w/cm), and the presence of fly ash as a cement replacement material on the conductivity of cement pastes is studied. The electrical conductivity–time relationships of cement pastes and concretes are expressed using a model that facilitates the extraction of initial and final conductivities, and a characteristic time parameter. These terms can be used to derive information about the microstructural changes occurring with time in cement pastes. A fractional factorial experiment scheme consisting of five factors—w/cm, fly ash content, aggregate–cementitious materials ratio (a/cm), aggregate size, and curing condition (saturated or sealed), with each factor at two levels (+1 or −1 corresponding to high and low levels)—is used for concrete mixtures. The experimental results are subjected to a range analysis to isolate the significant factors and factor interactions that influence the initial and final conductivities as well as the time parameter from the conductivity–time model for concrete mixtures. The a/cm exerts significant influence on both initial and final conductivities, whereas the amount of fly ash in the mixture, aggregate size, and curing condition influence the final conductivity of concretes. The w/cm and fly ash content were seen to influence the time parameter. Analysis of variance is conducted on the test results and the prominent two factor interactions that influence the conductivities and the time parameter are determined. The relationship between these responses and the parameters is expressed in terms of a least squares fit equation using the coded values for the variables.
Mechanical and fracture properties of normal- and high-strength concretes with fly ash after exposure to high temperatures
Authors: Tang W.C. , Lo T.Y.
Published: March 2009

This paper mainly reports an experimental investigation on the residual mechanical and fracture properties of normal and high-strength concrete (HSC) with and without fly ash after exposure to high temperatures ranging from 200 to 600°C. The fracture behaviour of concrete was investigated using the three-point bending notched beam test, according to RILEM recommendations. The effects of concrete strength, temperature level and the presence of fly ash on the fracture and mechanical properties of concrete were investigated. Some studies on the aggregate–cement paste transition zone have been made by means of a scanning electron microscope (SEM). The mechanical properties of concrete specimens significantly decreased with increase in temperature level, the extent of which depended on the presence of fly ash in the mix. In general, fly ash concrete performed better in residual mechanical and fracture properties especially at relatively high temperature levels than concretes without fly ash. Also, fewer and finer microcracks were identified in fly ash concrete under the SEM study.
The influence of the bond between concrete and reinforcement on tension stiffening effect
Authors: Pedziwiatr J.
Published: March 2009

This paper deals with the analysis of reinforced concrete structures with special emphasis on modelling of the bond influence on the tension stiffening effect. This effect is the reduction in deformation caused by concrete in tension after cracking and has great significance for calculation of serviceability limit states and nonlinear analyses. The most popular models for consideration of tension stiffening are based on semi-empirical formulae. It seemed that the bond concepts would make significant progress in this subject, but obtained results are rather disappointing. A new model for the bond phenomenon is proposed. It is based on the bond functions, which take into account not only the relative slip between a steel bar and surrounding concrete but also the position of the cross-section. They allow the direct calculation of the bond influence on crack spacing and width and tension stiffening. The form of these bond functions was positively verified on the specially designed specimens. The theoretical results obtained from the proposed model are very interesting and important for real-life situations. The cracking stage of loading determines the further behaviour of the member. The loss of stiffness just after cracking is very sharp and depends mainly on the steel/concrete ratio. For its small value, the stiffness after cracking is about only 12% of the uncracked value. Contrary to the commonly held belief, the bond itself has no significant influence on the changes in stiffness at this stage of loading. Similar conclusions are also valid for members under bending, but the degree of stiffness drop is smaller in terms of the compression zone and the moment distribution along a beam.
Economics of Five Wheat Production Systems with No‐Till and Conventional Tillage
Authors: Decker JonAnn E. , Epplin Francis M. , Morley Deena L. , Peeper Thomas F.
Published: March 2009

Conventional tillage (CT) continues to be used on the vast majority of land seeded to monoculture winter wheat (Triticum aestivum L.) in the Southern Plains of the United States. In the region, wheat can be grown for either grain‐only, forage‐only, or for both fall–winter forage + grain (dual‐purpose). This study was conducted to determine the net returns of five alternative wheat production systems, for both CT and no‐till (NT). The five production systems included one for forage‐only, two for dual‐purpose (fall–winter grazing + grain) with different planting dates, one grain‐only, and one forage‐only double cropped with foxtail millet [Setaria italica (L.) Beauv.]. The field research was conducted on three farm fields for 3 yr. Average wheat grain yields were greater with CT, whereas average fall wheat forage yields were significantly greater on the NT plots. Wheat hay and millet hay yields were not significantly different across tillage systems. Economic analysis was conducted for both a machinery complement sized for a 260‐ha farm and a machinery complement sized for a 1036‐ha farm. For both farm sizes and both tillage systems, the early‐September‐planted dual‐purpose system (ESD) produced the greatest net returns. For the 260‐ha farm, CT produced greater net returns than NT for each of the five production systems. Conventional tillage also produced greater economic returns for the three systems that included grain harvest for the 1036‐ha farm. However, for the larger farm size, NT generated greater net returns for both total forage systems.
Clinical Highlights From the American College of Cardiology’s 2024 Scientific Session
Authors: Abbasi Jennifer
Published: April 2024

This Medical News article is an interview with Douglas Drachman, MD, an interventional cardiologist and chair of the American College of Cardiology’s annual meeting.
A Novel Machine Learning Algorithm for Creating Risk-Adjusted Payment Formulas
Authors: Andriola Corinne , Ellis Randall P. , Siracuse Jeffrey J. , Hoagland Alex , Kuo Tzu-Chun , Hsu Heather E. , Walkey Allan , Lasser Karen E. , Ash Arlene S.
Published: April 2024

Importance

Models predicting health care spending and other outcomes from administrative records are widely used to manage and pay for health care, despite well-documented deficiencies. New methods are needed that can incorporate more than 70 000 diagnoses without creating undesirable coding incentives.

Objective

To develop a machine learning (ML) algorithm, building on Diagnostic Item (DXI) categories and Diagnostic Cost Group (DCG) methods, that automates development of clinically credible and transparent predictive models for policymakers and clinicians.

Design, Setting, and Participants

DXIs were organized into disease hierarchies and assigned an Appropriateness to Include (ATI) score to reflect vagueness and gameability concerns. A novel automated DCG algorithm iteratively assigned DXIs in 1 or more disease hierarchies to DCGs, identifying sets of DXIs with the largest regression coefficient as dominant; presence of a previously identified dominating DXI removed lower-ranked ones before the next iteration. The Merative MarketScan Commercial Claims and Encounters Database for commercial health insurance enrollees 64 years and younger was used. Data from January 2016 through December 2018 were randomly split 90% to 10% for model development and validation, respectively. Deidentified claims and enrollment data were delivered by Merative the following November in each calendar year and analyzed from November 2020 to January 2024.

Main Outcome and Measures

Concurrent top-coded total health care cost. Model performance was assessed using validation sample weighted least-squares regression, mean absolute errors, and mean errors for rare and common diagnoses.

Results

This study included 35 245 586 commercial health insurance enrollees 64 years and younger (65 901 460 person-years) and relied on 19 clinicians who provided reviews in the base model. The algorithm implemented 218 clinician-specified hierarchies compared with the US Department of Health and Human Services (HHS) hierarchical condition category (HCC) model’s 64 hierarchies. The base model that dropped vague and gameable DXIs reduced the number of parameters by 80% (1624 of 3150), achieved an R2 of 0.535, and kept mean predicted spending within 12% ($3843 of $31 313) of actual spending for the 3% of people with rare diseases. In contrast, the HHS HCC model had an R2 of 0.428 and underpaid this group by 33% ($10 354 of $31 313).

Conclusions and Relevance

In this study, by automating DXI clustering within clinically specified hierarchies, this algorithm built clinically interpretable risk models in large datasets while addressing diagnostic vagueness and gameability concerns.
CD44 and RHAMM Are Microenvironmental Sensors with Dual Metastasis Promoter and Suppressor Functions
Authors: Tolg Cornelia , Hill Kathleen Allen , Turley Eva Ann
Published: April 2024

The progression of primary tumors to metastases remains a significant roadblock to the treatment of most cancers. Emerging evidence has identified genes that specifically affect metastasis and are potential therapeutic targets for managing tumor progression. However, these genes can have dual tumor promoter and suppressor functions that are contextual in manifestation, and that complicate their development as targeted therapies. CD44 and RHAMM/HMMR are examples of multifunctional proteins that can either promote or suppress metastases, as demonstrated in experimental models. These two proteins can be viewed as microenvironmental sensors and this minireview addresses the known mechanistic underpinnings that may determine their metastasis suppressor versus promoter functions. Leveraging this mechanistic knowledge for CD44, RHAMM, and other multifunctional proteins is predicted to improve the precision of therapeutic targeting to achieve more effective management of metastasis.
Warm Pressing of Organosilicon Polymer Toward Monolithic Ceramics
Authors: Gowing Sion , Sabu Ummen , Bordia Rajendra K.
Published: April 2024

Warm pressing of organosilicon polymers is often challenging due to the formation of cracks due to release of volatile compounds during the warm pressing process. The focus of the present study is to warm press crosslinked SMP‐10 powders into crack‐free compacts and to pyrolyze them to get bulk SiC monoliths. Crack formation during warm pressing is addressed by optimizing the crosslinking temperature, and the loss of formability of the powders crosslinked at higher temperatures is overcome with the use of uncured polymer as a binder. The crosslinking temperature of the preceramic polymer plays a crucial role in developing crack‐free green bodies. The amount of binder used is varied to study its effect on the bulk density of the pyrolyzed product. The warm pressed green bodies pyrolyzed at 1400 °C result in the formation of bulk silicon carbide ceramics and are characterized using X‐ray diffractometer and FTIR spectroscopy. Warm pressing is performed at a lower temperature than reported in the literature, and this limits the incorporation of oxygen during the warm pressing.
Constructing High‐Content Sb Atomic Clusters and Robust Sb─O─C Bond in Sb/C Composites for Ultrahigh Rate and Long‐Term Sodium Storage
Authors: Xu Anding , Huang Mianying , Liu Chenxi , Li Teng , Li Xue , Wu Songping , Xu Zhiguang , Yan Yurong
Published: April 2024

Constructing Sb atomic clusters with obvious size effect in Sb/C composites has great potential for boosting electrochemical reactivity toward ultrahigh rate and long‐term sodium storage. However, how to balance the contradiction between ultra‐small size of Sb atomic clusters and high loading in a specific Sb/C composite is an unprecedented challenge. Here, a facile in situ vaporization‐reduction strategy is presented for preparing Sb atomic clusters@N, S co‐doped carbon networks (Sb ACs@NSC). Featuring the high content of Sb atomic clusters (45.30 wt%, ICP) with superior electrochemical activity, robust Sb─O─C bond and N, S co‐doped conductive carbon matrix, the Sb ACs@NSC electrode possessed ultrafast electrochemical kinetics and impressive long‐term cycling stability for providing unprecedented rate capability of 245.7 mAh g−1 at ultrahigh rate of 80 A g−1 and maintaining highlighted capacity of 306.7 mAh g−1 after 1000 cycles under 10 A g−1, outperforming all reported Sb‐based materials for SIBs. The DFT calculations further revealed that the Sb─O─C bond and N, S co‐doped carbon matrix are beneficial for stable adsorption capabilities and fast electrochemical kinetics of Na+. The designing compromised dense Sb atomic clusters and powerful interface bond will light on developing advanced atomic materials for energy storage and conversion.
Scalable Sol–Gel Permeation Assembly of Phase Change Layered Film Toward Thermal Management and Light‐Thermal Driving Applications
Authors: Han Gaojie , Cheng Hongli , Cheng Yajie , Zhou Bing , Liu Chuntai , Feng Yuezhan
Published: April 2024

Phase change materials (PCMs) are pivotal in thermal energy management and conversion applications owing to their exceptional thermal energy storage and release characteristics. However, persistent challenges such as poor thermal conductivity and leakage issues have impeded their widespread adoption. While existing approaches mitigate these challenges by constructing and incorporating 3D thermal conductive networks, they are constrained by discontinuous preparation methods and mold size limitations. Herein, a scalable sol–gel permeation assembly strategy is proposed to prepare phase change layered film by in situ filling polyethylene glycol (PEG) in aramid nanofibers (ANF)/graphene nanoplates (GNP) network. Befitting from the laminated network encapsulation effect of ANF and GNP, the phase change film demonstrates leak‐free and stable phase transition behavior, even after undergoing 500 heating/cooling cycles. Moreover, the resulting PEG/ANF/GNP layered film exhibits an impressive in‐plane thermal conductivity of 23.7 W mK−1 at GNP loading of 28.1 vol.%, rendering it suitable for thermal management applications in electronic devices. The phase change layered film possesses exceptional photo‐thermal conversion properties, maintaining temperatures exceeding 90 °C under a light power density of 200 mW cm−2. Capitalizing on the thermally induced flexibility of the phase transition film and its temperature‐dependent stiffness, its utility extended to developing a light‐thermal driving gripper.
Topological States Decorated by Twig Boundary in Plasma Photonic Crystals
Authors: Li Jianfei , Yao Jingfeng , Wang Ying , Zhou Zhongxiang , Lan Zhihao , Yuan Chengxun
Published: April 2024

The twig edge states in graphene‐like structures are viewed as the fourth states complementary to their zigzag, bearded, and armchair counterparts. In this work, a rod‐in‐plasma system in a honeycomb lattice with twig edge truncation under external magnetic fields and lattice scaling is studied and it is shown that twig edge states can exist in different phases of the system, such as quantum Hall (QH) phase, quantum spin Hall (QSH) phase, and insulating phase. The twig edge states in the negative permittivity background exhibit robust one‐way transmission properties immune to backscattering and thus provide a novel avenue for solving the plasma communication blackout problem. Moreover, it is demonstrated that corner and edge states can exist within the shrunken structure by modulating the on‐site potential of the twig edges. Especially, helical edge states with the unique feature of pseudospin‐momentum locking that can be excited by chiral sources are demonstrated at the twig edges. These results show that the twig edges and interface engineering can bring new opportunities for more flexible manipulation of electromagnetic waves.
Thermoregulated CPL‐Active Flexible Polymer/Perovskite Hybrid Materials with High Luminescence Dissymmetry Factor
Authors: Cao Rui , Zhou Xinning , Dai Haitao , Wang Yong , Xiao Yin
Published: April 2024

CPL‐active flexible materials with high luminescence dissymmetry factor (glum) and luminescent quantum yield are indispensable for 3D displays, wearable devices and so on. Perovskite has drawn much attention due to its fascinating photoelectric properties as well as its abundant applications. However, the existing strategies are inefficient in acquiring perovskite NCs with high glum. In this work, thermoregulated CPL‐active flexible polymer/perovskite hybrid materials with high glum by the creation of chiral photonic bandgap in polymer film with cholesteric domains using toluene as the dielectric media is reported. Based on selective CPL reflection, a satisfied CPL with a maximum glum of 0.6 is achieved. Importantly, the chiral photonic bandgap center of the polymer film can be easily tuned by thermal annealing at different temperatures to adapt various perovskite NCs with full‐spectral emission. The handedness of CPL of hybrid materials can be regulated with and without dielectric media. The presence of the flexible polymer makes hybrid materials a candidate to achieve patterned display applications. Additionally, the polymer/perovskite hybrid materials show excellent stability thanks to the encapsulation effect from polymers. This work provides a facile and general approach to induce adjustable CPL in the whole visible spectrum with high glum and photoluminescence quantum yield (PLQY).
Ligand Detachment—New Insight into the Mechanochromic Luminescence Mechanism of Copper Iodide Complexes with Thermally Activated Delayed Fluorescence
Authors: Li Haibo , Yang Jing , Wang Qianqian , Tong Hua , Zhu Jialin , Liu Wei , Ouyang Gangfeng
Published: April 2024

Mechanochromic luminescence materials have recently attracted increasing interest due to its promising applications, but the intensive inquiry of the mechanochromic luminescence mechanism is still insufficient. Herein, an in‐depth study of mechanochromic luminescent copper iodide complexes exhibiting ligand detachment and structural transformation is reported. The yellowish–green emissive CuI(dmpz) (dmpz = 2,6‐dimethylpyrazine) is ground into orange–red emissive CuI(dmpz)0.5 and the detailed structural transformation process is revealed by the thorough analysis of the crystalline structure before and after grinding. More importantly, new insight into the mechanochromic luminescence mechanism is proposed, that is, under the external force of grinding, the dmpz ligand detachment triggers the structural transformation from 1D chain to 2D network, which leads to the reduction of band gap energy and contraction of Cu─Cu bonds, together resulting in the red shift of luminescence ultimately. Moreover, the two complexes are also found to have thermochromic luminescence properties, attributing to their thermally activated delayed fluorescence process. The anti‐counterfeiting application of CuI(dmpz) is tentatively explored, demonstrating the favorable application prospect of CuI(dmpz). This study provides new insights involved in the mechanochromic luminescence mechanism of copper iodide complexes, and may provide a new understanding for rational molecular design and structural regulation of intelligent responsive luminescence.
Embedding Bifurcations into Pneumatic Artificial Muscle
Authors: Akashi Nozomi , Kuniyoshi Yasuo , Jo Taketomo , Nishida Mitsuhiro , Sakurai Ryo , Wakao Yasumichi , Nakajima Kohei
Published: April 2024

Harnessing complex body dynamics has long been a challenge in robotics, particularly when dealing with soft dynamics, which exhibit high complexity in interacting with the environment. Recent studies indicate that these dynamics can be used as a computational resource, exemplified by the McKibben pneumatic artificial muscle, a common soft actuator. This study demonstrates that bifurcations, including periodic and chaotic dynamics, can be embedded into the pneumatic artificial muscle, with the entire bifurcation structure using the framework of physical reservoir computing. These results suggest that dynamics not present in training data can be embedded through bifurcation embedment, implying the capability to incorporate various qualitatively different patterns into pneumatic artificial muscle without the need to design and learn all required patterns explicitly. Thus, this study introduces a novel approach to simplify robotic devices and control training by reducing reliance on external pattern generators and the amount and types of training data needed for control.
Drugtamer‐PROTAC Conjugation Strategy for Targeted PROTAC Delivery and Synergistic Antitumor Therapy
Authors: He Shipeng , Fang Yuxin , Zhu Yaojin , Ma Ziyang , Dong Guoqiang , Sheng Chunquan
Published: April 2024

Proteolysis‐targeting chimeras (PROTACs) have emerged as a promising strategy for targeted protein degradation and drug discovery. To overcome the inherent limitations of conventional PROTACs, an innovative drugtamer‐PROTAC conjugation approach is developed to enhance tumor targeting and antitumor potency. Specifically, a smart prodrug is designed by conjugating “drugtamer” to a nicotinamide phosphoribosyltransferase (NAMPT) PROTAC using a tumor microenvironment responsible linker. The “drugtamer” consists of fluorouridine nucleotide and DNA‐like oligomer. Compared to NAMPT PROTAC and the combination of PROTAC + fluorouracil, the designed prodrug AS‐2F‐NP demonstrates superior tumor targeting, efficient cellular uptake, improved in vivo potency and reduced side effects. This study provides a promising strategy for the precise delivery of PROTAC and synergistic antitumor agents.