Knowledge diffusion under patent with asymmetric firms

We show that if patent protection and trade secrecy generate asymmetric market structure, an innovator may prefer patent protection than trade secrecy even if the diffusion probability is higher under the former but it increases market concentration by preventing some imitators. So, whether an innovator prefers patent protection or trade secrecy depends on the trade-off between the diffusion probability and market concentration.

DEGRADATION OF YIELD STRENGTH OF LATERALLY LOADED WOOD-TO-ORIENTED STRANDBOARD CONNECTIONS AFTER EXPOSURE TO ELEVATED TEMPERATURES

Wood to sheathing connections is crucial to lateral force resisting system of the wood-frame structure. Engineers are often faced with the challenge of predicting strength of a partially damaged structure after it has been exposed to elevated temperature during a fire. Numerical simulations to predict the residual strength need thermal degradation data and models for the material as well as the connections. Therefore, it is important to categorize connection response when exposed to elevated temperatures for a sustained period of time. This study addresses this issue by developing models to predict lateral yield strength degradation of wood to Oriented Strandboard (OSB) connection after exposure to elevated temperature. A total of 394 Douglas-fir to OSB connections were tested laterally as a function of 8 different temperatures and 8 exposure times within each temperature regime. Yield strength of the connection decreased as a function of temperature and exposure time. Rate of degradation was higher at higher temperatures. A regression-based statistical model was developed. Additionally, these results were fit to a 2-step simple kinetics model, based on the assumption of degradation kinetics following an Arrhenius activation energy model. The kinetics-based model was preferred over regression model as it fit the data better with one less parameter and predictions consistently matched the observed values for an independent data set

Export cartel and consumer welfare

The purpose of this paper is to show that export cartels are not necessarily harmful for consumers in the importing countries. Using the strategic trade policy model of Brander and Spencer (1985a), we show that, contrary to the harmful effect, product-market cooperation benefits consumers by affecting the trade policies. We further show that consumers in the importing countries are affected adversely if cooperation is among the governments of the exporting countries, instead of the exporting firms

Lateral Load-Carrying Connection Properties and Withdrawal Capacity of Hybrid Poplar

An experimental study is reported aimed at determining the yield load, withdrawal capacity, and validity of National Design Specification (NDS) yield models on connections between hybrid poplar and common sheathing materials using a dowel-type fastener. Plantation-grown hybrid poplar (Pacific Albus) was procured, and connections with two different thicknesses of oriented strandboard and plywood were constructed using a dowel-type fastener. The NDS does not list connection design values for low-density wood species. Therefore, it was important to validate the NDS yield model equations for applicability toward a low-density species such as hybrid poplar. The results quantify the lateral load-carrying and withdrawal capacities of hybrid poplar. Also, the prediction using NDS yield models consistently matched the observed yield loads and yield modes for all the sheathing types used in this study. The data suggest that the NDS yield model is an adequate tool for connection design even for low-density species, provided knowledge of dowel-bearing capacity of the hybrid poplar is known

Synthesis, characterization and in vitro biocompatibility study of strontium titanate ceramic: A potential biomaterial

Strontium (Sr), a mineral element present in trace in the human body, has significant effect on bone remodelling. Sr containing ceramics have huge potential to heal bone defects and improve osseointegration of implants. In this study, perovskite oxide – strontium titanate (SrTiO3) was synthesized and explored its potential for biomedical applications. The phase pure SrTiO3 powder was synthesized from solid state reaction of strontium carbonate (SrCO3) and titanium dioxide (TiO2) at 1200 °C for 2 h. The as synthesized SrTiO3 powder, pure hydroxyapatite (HAp) and SrTiO3-50 wt% HAp (SH50) premixed powders were sintered at different temperatures varies from 1100 to 1400 °C in air. The sintered samples were characterized using X-ray diffraction (XRD) for phases and scanning electron microscopy (SEM) for microstructure analysis. XRD results revealed no dissociation of HAp or reaction with SrTiO3 during sintering. The sintered samples were studied for mechanical properties, wettability, and biocompatibility. The relative density of the sintered SrTiO3 increases with increasing sintering temperature. The relative density of SrTiO3 was increased from 77% to 98% with increase in sintering temperature from 1250 to 1400 °C. The substantial improvement of hardness and compressive strength was observed for sintered SrTiO3 compared to HAp of similar porosity level. The hardness and compressive strength of SrTiO3 sintered at 1250 °C found ~6 and ~3.5 times higher than sintered HAp. In vitro dissolution study carried out in phosphate buffer solution at 37 °C, confirmed the release of Sr2+ ion from the bulk SrTiO3 sintered at 1250 °C. The in vitro cell materials interaction showed cytocompatibility of sintered SrTiO3 and SrTiO3-HAp composite. In summary, excellent biocompatibility of SrTiO3 with superior mechanical properties confirmed its potential as novel biomaterial for use in the repair of infected or aseptic bone defects

Quantifying environmental impacts of poplar biomass production in the U.S. Pacific Northwest

The life cycle impacts were determined for poplar-managed four ways in the Pacific Northwest of the United States. Two sites had 3-yr rotations and either no irrigation (Site 1) or irrigation with river water (Site 2). The other sites had 12-yr rotations and irrigation with wastewater from a treatment facility (Site 3) or irrigation with landfill leachate (Site 4). Primary data for land preparation, plantation management, harvesting, and land restoration at each site and the production of cuttings at an additional facility were collected. A cradle to gate life cycle assessment was conducted using SimaPro PhD v8 based on the primary data and secondary data from the US life cycle inventory and ecoinvent v3 database to create a life cycle inventory. Impact indicators were provided by TRACI model. Short rotations resulted in lower global warming impact per unit output (79.5 and 54.5 kg CO2 eq/t) and energy consumption (1381.8 and 877.4 MJ/t) than long rotations (93.1 and 81 kg CO2 eq/t and 1406.9 and 1343.5 MJ/t) mainly due to reduced diesel use. Higher planting densities resulted in greater water and electrical consumption attributed to cuttings. Pesticide and herbicide use strongly affected ozone depletion and eutrophication, whereas fuel consumption had strong effects on global warming impact, smog, and acidification. Increasing biomass yield reduced impacts. When the electricity was all from biomass, global warming and acidification decreased; however, ozone depletion, smog, and eutrophication increased. The results suggested that both, herbicide application during plantation management and diesel consumed during harvesting at these sites should be optimized to decrease the environmental impacts. 

Postpeak residual capacity of nailed connections of a shear wall

To quantify the postpeak residual capacity and to gain insights into the load transfer mechanism of a shear wall, nail connection tests were performed on salvaged connections after a monotonic shear wall test loaded up to peak load. Experimental results reveal that there is a loss of strength in most of the fasteners studied, indicating that almost all the fasteners contribute toward racking resistance of the wall. The maximum loss of strength was observed for the fastener in the uplift corner and for the fastener along the middle stud. Another area where fasteners exhibited a significant loss of strength was in plate connection located at the bottom plate. The performance of a shear wall can be enhanced by strengthening the two areas – uplift corner and bottom plate.This is the publisher’s final pdf. The published article is copyrighted by Walter de Gruyter GmbH and can be found at: http://www.degruyter.com/view/j/hfsg.Keywords: racking resistance, uplift corner, yield strength, national design specification, strength loss, nail connection test, bottom plate, wood-frame shear wall, load transfe

The effect of elevated temperature on mechanical behavior of structural wood and wood-based composites

Engineers, in practice, are often faced with the challenge of evaluating a fire-damaged structure and developing a rehabilitation and retrofit plan. In order to decide on a rehabilitation and retrofit plan, information on thermal degradation of building materials and connections are vital. A critical knowledge gap exists in terms of thermal degradation of materials and connections with respect to light-frame wood construction. Along with solid sawn lumber (SSL), various wood-based composites such as plywood, oriented strand board (OSB) and laminated veneer lumber (LVL) are also used in wood-frame construction. Characterization of the thermal degradation of strength of these structural materials will help assess the service life and strength of the damaged structure. This study addressed the thermal degradation of material strength and connection strength by conducting tests on wood, wood-based composites and connections after subjecting them to elevated temperatures, hence studying the post-fire residual strength in wood and wood composite construction. The properties evaluated in this study were bending strength (MOR), bending stiffness (MOE), lateral nail capacity, dowel bearing strength, fracture toughness and bond strength (IB) after exposing the materials to elevated temperature for various exposure times. In addition, the bending strength of OSB and plywood was studied in great detail as a function of additional temperatures and exposure times. A general trend of degrading bending properties, fracture toughness, dowel bearing strength of materials and yield strength of the connections of various configurations with high temperature and duration of exposure was observed and confirmed by statistical analysis. A statistical regression based model incorporating the effects of temperature, time of exposure and thier interaction and a model based on first-order kinetics were developed and evaluated for predicting the strength loss. The kinetics-based model was better than the regression-based approach. Using the kinetics analysis along with time-temperature superposition for OSB and plywood, a master curve was generated at a reference temperature of 150°C that can be used for residual strength estimates and failure time predictions. A reasonable prediction of connection design values was made using National Design Specifications (NDS) yield models for thermally degraded materials. Conventional tests for bond strength provided excessive scatter which renders any statistical comparison highly difficult. An alternative to IB and bond classification could be fracture testing using energy methods for wood bond strength evaluation. The various analytical models developed will help for characterizing the thermal degradation of material properties. Models specified in design codes were evaluated against the thermal degradation of materials. This knowledge of thermal degradation and the models will help engineers and architects in recommending categorical improvement, rehabilitation and retrofit of structures

Effects of Outdoor Exposure on Properties of I-Joists

Wood I-joists are often left uncovered and exposed to the weather during construction, allowing the oriented strandboard and laminated veneer lumber in these systems to be adversely affected by water absorption. Manufacturers typically specify that these materials be protected from wetting, but this can be difficult in wetter climates. There are few studies examining the potential effects of wetting on these building elements. In this study, flexural properties and ultimate tensile strength of I-joists exposed for extended periods of time during the rainy winter months in the Willamette Valley of western Oregon were evaluated. I-joists were removed from the field each month, dried, and then tested in static bending (flexure) using a six-point bending test. I-joist strength decreased as a function of exposure time and rainfall. Twenty-seven da of external exposure was associated with a significant increase in flexural variability. Further exposure was associated with significant decreases in I-joist strength (modulus of rupture). Although most I-joists never experience this degree of wetting, they can when construction is delayed. The results illustrate the detrimental effects of exposure to wetting during construction and support improved efforts to limit wetting

Limb salvage surgery with endoprosthesis reconstruction in management of locally advanced primary bone tumours: a functional outcome evaluation

Background: Endoprosthetic reconstruction using a custom-made metallic mega-endoprosthesis is one of the common modalities for limb salvage operation. The new promising advance of material science, design and fabrication of the endoprosthesis enable an immediate rehabilitation program and provide a durable and functional limb. The aim of the study was to evaluate the efficacy and functional outcome in patients with primary bone tumours treated by limb salvage surgery using endoprosthetic replacement.Methods: A total of 14 patients with primary bone tumour in major large joints of the body, selected between January 2019 to August 2020, were managed by limb salvage surgery via endoprosthetic replacement. This was a prospective study conducted at a Tertiary care Government Hospital in Kolkata, and all patients were followed up to a minimum of 1.5 years. The evaluation system used was proposed by Enneking, recommended by the musculoskeletal tumour society in addition to the radiologic evaluation.Results: At final follow-up, the mean musculoskeletal tumour society score was 89.71±3.58. The mean Knee Society Score of 9 patients was 85.55±3.64 and mean Harris hip score of 2 patients and Oxford shoulder score of 4 patients were 90.5 and 41.67 respectively by the end of 1.5 years. 12 (85.7%) patients did not have any complications. None of the cases had implant loosening or breakage, periprosthetic fracture, tumour recurrence or amputation.Conclusions: Endoprosthesis are excellent choices for the treatment of bone tumours with limb preservation in relation to pain, strength, and patient’s emotional acceptance as they reconstruct a limb with an acceptable oncologic, functional, and cosmetic result providing immediate weight-bearing capacity and generating a greater independence