bluuebunny/crossref_metadata_2025 huggingface dataset:
Multi-criteria aerodynamic optimization of wind farm energy efficiency based on genetic algorithms
Authors: Rašuo Boško , Bengin Aleksandar , Dinulović Mirko
Published: January 2024

In this paper, the possibilities of using parallel processing algorithms and methodologies were analyzed in order to more efficiently solve the very complex problem of multi-criteria aerodynamic optimization in order to achieve the maximum energy efficiency of the entire wind farm, which is based on genetic optimization algorithms. It has been shown that the best results are obtained by applying the genetic algorithm method of distributive differential evolution. The program algorithm was written using MPI routines for communication between processors and was executed on a computer cluster located at the Faculty of Mechanical Engineering of the University of Belgrade within the SimLab laboratory.
Exploring linguistic signage in higher education: An empirical study of a linguistically diverse context
Authors: Clorion Frenz Djaxxas Daleon , Bulado Aubrey Jane , Encarnacion Bernadeth A. , Dumagay Alexandhrea Hiedie , Ellomer Guiller A. , Albani Salman E. , Pil Anthony O. , Devanadera Aprillette C. , Rillo Richard M. , Alrefaee Yasser , Alieto Ericson O.
Published: January 2024

This study offers a comprehensive examination of the linguistic landscape in a nonmetropolitan university, focusing on the dominant language used in university signage. The study primarily delves into the multilingual characteristics and nature of Western Mindanao State University, situated in a linguistically-diverse environment. The study employed analytical categories, which was utilized to serve as basis in selecting and gathering data from various signages across the university, to ensure the accuracy of the data collection. The findings of the study indicated that the university contains five (5) languages that make its linguistic landscape, specifically: English (95.51%), Filipino (7.81%), Chavacano (3.07%), Tausug (1.28%), and Bisaya (0.64%). The data was analyzed using the content analysis to accurately interpret the taken photographs in the university. The study also uncovers the inequality of the number of signages, wherein majority of the signages are monolingual nature, and only limited on the bilingual and multilingual signs. The investigation also revealed a significant result that English is the dominant language used on signages despite the locale’s diverse linguistic and cultural background. The major findings of this study portray that Western Mindanao State University employs both official and non-official signages throughout the campus and in terms of linguistic diversity, local languages are not entirely prevalent and observable on the signages across the entire campus. Consequently, despite the university’s focus towards internationalization and global excellence, there is observable scarcity in multilingual signages. It is imperative to acknowledge the value of multilingual signages, not only for the purpose of communication, but for the preservation of local languages, that are crucial for cultural and ethnic representations.
Crustal response to water loads and expansion of triggered seismicity around the Xiluodu Reservoir, Southwest China
Authors: Shi Xuhua , Shu Yuanhai , Bürgmann Roland , Xie Lei , Han Libo , Cao Zhongcheng , Xu Wenbin , Wang Teng , Chen Hanlin , Madson Austin , Kirby Eric , Meng Guojie , Lu Renqi , Yao Qi , Cheng Xiaogan , Yang Shufeng
Published: January 2024

The transition to low-carbon energy generation requires a diverse portfolio of energy sources. Large hydropower stations play a crucial role in providing eco-friendly energy but can lead to crustal deformation and seismic activity due to reservoir impoundment and discharge. The mechanism behind how impoundment-induced deformation influences reservoir-triggered seismicity remains unclear. We investigate this at the world��s 4th largest hydropower station in Xiluodu, China, using interdisciplinary analyses of relocated earthquakes, geodetic data, and numerical simulations. Geodetic observations confirm both a linear elastic response to hydrologic loading and the transition towards a relaxed and flexural response. Notably, approximately 81% of the earthquakes since impoundment occurred within ~15 km of the subsidence center. These events temporally relate to rapid hydrologic loading/unloading periods, with their spatiotemporal outward migration potentially caused by viscous relaxation of load stresses in the lower crust and upper mantle. The reservoir-induced flexural deformation and subsequent viscous relaxation may control the distribution and expansion of triggered seismicity. This research highlights the urgent need to enhance geohazard monitoring efforts around the subsidence center and emphasizes the vital importance of carefully considering this factor during the construction of large reservoirs to mitigate potential seismic risks.
Predicting microbial nutrient limitations from a stoichiometry-based threshold framework
Authors: Cui Yongxing , Moorhead Daryl L. , Peng Shushi , Sinsabaugh Robert L. , Peñuelas Josep
Published: January 2024

While ecological stoichiometry-based theories and methodologies have been successfully applied to identify nutrient limitations in plankton and plants (e.g., leaf nutrient resorption ratios), determining nutrient limitations in soil microorganisms by them has great uncertainties. Establishing stoichiometric thresholds that define specific nutrient limitations for soil microbial communities has been a major challenge. Here, we present a threshold framework that predicts the limitations of carbon (C), nitrogen (N), and phosphorus (P) for microbial communities by leveraging the convergence of elemental stoichiometry from soils to microorganisms. Combined with a widely used model of microbial nutrient limitations (i.e., ecoenzyme vector model), the theoretical thresholds derived from this framework are validated by empirical thresholds identified through analysis of a comprehensive global dataset (n = 3277). Notably, we find that the commonly assumed threshold of 45�� in the ecoenzyme vector model overestimates microbial P limitation and underestimates microbial N limitation. By contrast, a vector length of 0.61 (unitless) and an angle of 55�� in the vector model are more reliable thresholds identifying microbial C and N/P limitations, respectively. This framework, with a fundamental understanding of microbially-driven stoichiometric convergence in plant-soil-microbe systems, offers a practical and general avenue for identifying microbial nutrient limitations in soils.
Non Parametric Trend Analysis of Tea Cultivation in India
Authors: Chandran Arya V. , Dhakre D. S. , Bhattacharya Debasis , Sarkar K. A.
Published: January 2024

With the second-largest producer and the highest consumer in the world, tea is one of the most important beverage crops in India. Considering the importance of tea industry to India’s national economy, a trend analysis of tea cultivation has been done here. Using data on the acreage, production, and productivity of tea in India from 1960 to 2021, and following a non-parametric approach Modified Mann-Kendall test has been used to detect the trend in the data. Addition to this, Sen’s slope estimator and innovative trend analysis have been performed to analyze the magnitude of trend whereas the Pettitt Mann-Whitney test has been used to detect the single change point. The findings of tests revealed that the area, production and productivity of tea in India have significantly increasing trend over the years.
BILATERAL PROJECT REPORT IMPACT OF QUARANTINE DUE TO COVID-19 ON THE MUSIC INDUSTRY IN SLOVENIA AND BOSNIA AND HERZEGOVINA
Authors: Raspor Andrej , Kleindienst Petra , Ljubotina Predrag , Rojko Bojan , Mastilo Zoran , Stošić Lazar ,   Faculty of Management, Sremski Karlovci, University UNION Nikola Tesla, Belgrade, Mrkaić Ateljević Andrijana , Miletić Vesna , Mastilo Dejan
Published: January 2024

BILATERAL PROJECT REPORT IMPACT OF QUARANTINE DUE TO COVID-19 ON THE MUSIC INDUSTRY IN SLOVENIA AND BOSNIA AND HERZEGOVINA
The Mananambals and Their Functions in Philippine Culture
Authors: Crisol Lourd Greggory , Oledan Efren Jone
Published: January 2024

This qualitative study attempts to look into the practice of folk healing used by mananambals or folk healers in Iligan City, Philippines. It also looks into the functions that these traditional practitioners serve in the Philippine culture. Anchored in the functionalist theory in anthropology by Bronislaw Malinowski and supplemented by the national folklore theory by Richard Dorson, this study attempts to answer the following questions: (1) What are the backgrounds and practices of the mananambals? (2) What do the mananambals’ background and practices reveal of Filipino culture? (3) From these reflections, what functions do the mananambals have in Philippine culture? Upon analysis, it was revealed that these mananambals obtained their healing abilities through supernatural means. In terms of diagnosing illnesses, they examine certain body parts and bodily functions, but still also ask for guidance from spirit guides. They cure illnesses by using certain folk medicines, incantations, and traditional massage. For protection from harm and illnesses, they use natural means but these are accompanied by amulets and trinkets. Moreover, it was found out that for Filipinos, health and illness are deeply rooted in spiritual and folk beliefs. More importantly, these mananambals remind Filipinos

of the value of community and spirituality.
Towards Dehegemonizing the English Language: Perspectives of a “Center” ResearcherWorking in the Periphery
Authors: McLellan James
Published: January 2024

This article takes as its starting point the phrase “towards dehegemonizing the English language”, used in the rationale for this conference and workshop. The presentation draws on the insights of Southeast Asian scholars including Tupas (Unequal Englishes), Lorente (the grip of English and Philippine language policy), and Noor Azam (It’s not always English: Duelling aunties in Brunei Darussalam). Noting with approval these examples of ‘periphery’ scholars writing back and exploring the ways in which English has become an Asian language, I offer examples of mixed and unmixed language use in language and content classrooms for collaborative analysis with the audience, and other spoken, written and social media texts for comparison and contrast. These should enable us to explore: whether classroom language use reflects the world outside; whether we can move towards a more accommodating multilingual model; whether this can help us to view local and global languages as complimentary The conclusion suggests a reconceptualization of Applied Linguistics and supports the development of theories arising from Southeast Asian multilingual contexts.
THE RELATIONSHIP OF THE QUALITY OF SCHOOL LIFE WITH THE TRUTCHING BEHAVIOR OF PRIVATE HIGH SCHOOL STUDENTS IN KURANJI DISTRICT, PADANG CITY
Authors: Al Ghazali Jihad , Aulia Farah
Published: January 2024

Truant behavior is a problem in the world of education that has a negative impact on students, such as missing lessons and being expelled from school. The aim of this research was to determine the relationship between the quality of school life and truant behavior. This research is a quantitative correlation type research. Data collection techniques in this research were a quality of school life scale and a truant behavior scale. The research subjects of this study were 62 grade 11 students from 3 private high schools in Kuranji District, Padang City. The sampling technique uses total sampling. The data analysis technique used is product moment analysis. The results of this hypothesis test show that the correlation coefficient is r=-0.836 with a significance of p=0.00 (p<0.05). The results of this research show that there is a negative relationship between the quality of school life and truancy behavior among private high school students in Kuranji District, Padang City.
TLR2 Regulates Hair Follicle Cycle and Regeneration via BMP Signaling
Authors: Xiong Luyang , Zhevlakova Irina , West Xiaoxia Z. , Gao Detao , Murtazina Rakhylia , Horak Anthony , Brown J. Mark , Molokotina Iuliia , Podrez Eugene A. , Byzova Tatiana V.
Published: January 2024

The etiology of hair loss remains enigmatic, and current remedies remain inadequate. Transcriptome analysis of aging hair follicles uncovered changes in immune pathways, including Toll-like receptors (TLRs). Our findings demonstrate that the maintenance of hair follicle homeostasis and the regeneration capacity after damage depends on TLR2 in hair follicle stem cells (HFSCs). In healthy hair follicles, TLR2 is expressed in a cycle-dependent manner and governs HFSCs activation by countering inhibitory BMP signaling. Hair follicles in aging and obesity exhibit a decrease in both TLR2 and its endogenous ligand carboxyethylpyrrole (CEP), a metabolite of polyunsaturated fatty acids. Administration of CEP stimulates hair regeneration through a TLR2-dependent mechanism. These results establish a novel connection between TLR2-mediated innate immunity and HFSC activation, which is pivotal to hair follicle health and the prevention of hair loss and provide new avenues for therapeutic intervention.Hair follicle stem cells TLR2 is required for hair homeostasis and regeneration. While TLR2 stimulation by endogenous ligand promotes hair growth, reduction in TLR2 and its ligand in aging and obesity may diminish hair growth.
Synthetic Biology and International Regulatory Law
Authors: Getie Birhan , Andualem Berhanu
Published: January 2024

For the purpose of constructing or generating new life forms, synthetic biology is a multidisciplinary field that blends biology with engineering, physics, mathematics, chemistry, and computer science. Making Biobricks, designing metabolic pathways, whole-genome synthesis, protocell engineering, and Xenobiology are the primary synthetic biology techniques. Synthetic biology spans a variety of industries, including pharmaceuticals, energy, chemicals, biosensors, and environmental protection. Although it has various uses, there are risk issues with biosafety, biosecurity, and bioethics. Strong regulatory rules must be developed in order to increase the risks associated with sedentary behavior. The Cartagena protocol recognizes some synthetic biology applications and outcomes as living modified organisms. The protocol's advance informed agreement governs the trans-boundary transfer of living, synthetically modified organisms. Dual-use technologies are governed by laws agreed under the Biological Weapons Convention and relate to synthetic biology products. Synthetic biology also makes use of the Nagoya Protocol, trade-relevant IP rights, and other legislative frameworks. However, because synthetic biology is a young field of study, there are no explicit regulations governing it in any way under international law. The purpose of this review is to evaluate the regulatory regulations governing synthetic biology and to describe the applications and hazards of synthetic biology.
On the Fringe of Neolithic Europe
Authors: Ritchie Anna
Published: January 2024

The stalled cairn of Holm of Papa Westray North (OR K 21) in the far north of Orkney was excavated in 1854 and 1982–3. It was preceded by a small cell in a round cairn, which was amalgamated within the rectangular cairn of the stalled chamber. The cell was filled and walled off within the life of the stalled chamber, and the latter, with its entrance passage, was similarly filled at the end of its use, with evidence of deliberate selection of organic material included in the filling, particularly limpet shells and red deer antler. The remains of a minimum of eight to nine human individuals were found within the tomb, and the remains of neonate lambs show that sheep had access to the stalled chamber before it was sealed. Plain bowls were associated with the chamber deposits and Grooved Ware and beaker with secondary structures outside the cairn. Radiocarbon dates indicate that the tomb was in use for burials during the period from about 3520 cal bc to about 2900 cal bc and thus was contemporary with both the settlement at Knap of Howar in adjacent Papa Westray and the stalled cairn at Point of Cott in Westray. Stable carbon isotope and iodine analysis of teeth has demonstrated that the Neolithic sheep on the Holm were eating seaweed in the winter months, and isotope analysis of human bones indicates that the local population had a diet that included a small amount of marine protein. Vole remains exhibit the features that make the modern Orkney vole unique and thus confirm that this divergence from the European norm dates back to later Neolithic times. The fishbone assemblage indicates both otter and human activity within the chamber.
Clinical Outcomes Following Institution of the Canadian Universal Leukoreduction Program for Red Blood Cell Transfusions
Authors: Hébert Paul C. , Fergusson Dean , Blajchman Morris A. , Wells George A. , Kmetic Andrew , Coyle Doug , Heddle Nancy , Germain Marc , Goldman Mindy , Toye Baldwin , Schweitzer Irwin , vanWalraven Carl , Devine Dana , Sher Graham D. ,   for the Leukoreduction Study Investigators
Published: April 2003

Context

A number of countries have implemented a policy of universal leukoreduction of their blood supply, but the potential role of leukoreduction in decreasing postoperative mortality and infection is unclear.

Objective

To evaluate clinical outcomes following adoption of a national universal prestorage leukoreduction program for blood transfusions.

Design, Setting, and Population

Retrospective before-and-after cohort study conducted from August 1998 to August 2000 in 23 academic and community hospitals throughout Canada, enrolling 14 786 patients who received red blood cell transfusions following cardiac surgery or repair of hip fracture, or who required intensive care following a surgical intervention or multiple trauma.

Intervention

Universal prestorage leukoreduction program introduced by 2 Canadian blood agencies. A total of 6982 patients were enrolled during the control period and 7804 patients were enrolled following prestorage leukoreduction.

Main Outcome Measures

All-cause in-hospital mortality and serious nosocomial infections (pneumonia, bacteremia, septic shock, all surgical site infections) occurring after first transfusion and at least 2 days after index procedure or intensive care unit admission. Secondary outcomes included rates of posttransfusion fever and antibiotic use.

Results

Unadjusted in-hospital mortality rates were significantly lower following the introduction of leukoreduction compared with the control period (6.19% vs 7.03%, respectively; P = .04). Compared with the control period, the adjusted odds of death following leukoreduction were reduced (odds ratio [OR], 0.87; 95% confidence interval [CI], 0.75-0.99), but serious nosocomial infections did not decrease (adjusted OR, 0.97; 95% CI, 0.87-1.09). The frequency of posttransfusion fevers decreased significantly following leukoreduction (adjusted OR, 0.86; 95% CI, 0.79-0.94), as did antibiotic use (adjusted OR, 0.90; 95% CI, 0.82-0.99).

Conclusion

A national universal leukoreduction program is potentially associated with decreased mortality as well as decreased fever episodes and antibiotic use after red blood cell transfusion in high-risk patients.
Clinical Outcomes Following Institution of Universal Leukoreduction of Blood Transfusions for Premature Infants
Authors: Fergusson Dean , Hébert Paul C. , Lee Shoo K. , Walker C. Robin , Barrington Keith J. , Joseph Lawrence , Blajchman Morris A. , Shapiro Stan
Published: April 2003

Context

Leukocytes present in stored blood products can have a variety of biological effects, including depression of immune function, thereby increasing nosocomial infections and possibly resulting in organ failure and death. Premature infants, given their immature immune state, may be uniquely predisposed to the effects of transfused leukocytes.

Objective

To evaluate the clinical outcomes following implementation of a universal prestorage red blood cell (RBC) leukoreduction program in premature infants admitted to neonatal intensive care units (NICUs).

Design and Setting

Retrospective before-and-after study conducted in 3 Canadian tertiary care NICUs from January 1998 to December 2000.

Patients

A total of 515 premature infants weighing less than 1250 g who were admitted to the NICU, received at least 1 RBC transfusion, and survived at least 48 hours were enrolled. The intervention group consisted of infants admitted in the 18-month period following the introduction of universal leukoreduction (n = 247) and the control group consisted of infants admitted during the 18 months prior to the introduction of universal leukoreduction (n = 268).

Main Outcome Measures

Primary outcomes were nosocomial bacteremia and NICU mortality, compared before and after implementation of universal leukoreduction using multivariate regression. Secondary outcomes included bronchopulmonary dysplasia, retinopathy of prematurity, necrotizing enterocolitis, and intraventricular hemorrhage.

Results

The proportion of infants who acquired bacteremia after an RBC transfusion was 79/267 (29.6%) in the nonleukoreduction period and 63/246 (25.6%) in the leukoreduction period. For NICU mortality, there were 45 deaths (16.8%) in the nonleukoreduction period and 44 deaths (17.8%) in the leukoreduction period. The adjusted odds ratio (OR) for bacteremia was 0.59 (95% confidence interval [CI], 0.34-1.01) and for mortality was 1.22 (95% CI, 0.59-2.50). The adjusted ORs for bronchopulmonary dysplasia and retinopathy of prematurity were 0.42 (95% CI, 0.25-0.70) and 0.56 (95% CI, 0.33-0.93), respectively. The adjusted ORs for necrotizing enterocolitis and grade 3 or 4 intraventricular hemorrhage were 0.39 (95% CI, 0.17-0.90) and 0.65 (95% CI, 0.35-1.19), respectively. The adjusted OR for a composite measure of any major neonatal morbidity was 0.31 (95% CI, 0.17-0.56). Crude and adjusted rates for all secondary outcomes suggest that leukoreduction was associated with improved outcomes.

Conclusion

Implementation of universal prestorage leukoreduction was not associated with significant reductions in NICU mortality or bacteremia but was associated with improvement in several clinical outcomes in premature infants requiring RBC transfusions.
Improving the Process of Informed Consent in the Critically Ill
Authors: Davis Nicole , Pohlman Anne , Gehlbach Brian , Kress John P. , McAtee Jane , Herlitz Jean , Hall Jesse
Published: April 2003

Context

Invasive procedures are often performed emergently in the intensive care unit (ICU), and patients or their proxies may not be available to provide informed consent. Little is known about the effectiveness of intensivists in obtaining informed consent.

Objectives

To describe the nature of informed consent in the ICU and to determine if simple interventions could enhance the process.

Design, Setting, and Patients

Prospective study of 2 cohorts of consecutively admitted patients (N = 270) in a 16-bed ICU at a university hospital. All patients admitted to the ICU during the baseline period from November 1, 2001, to December 31, 2001, and during the intervention period from March 1, 2002, to April 30, 2002, were included.

Intervention

A hospital-approved universal consent form for 8 commonly performed procedures (arterial catheter, central venous catheter, pulmonary artery catheter, or peripherally inserted central catheter placement; lumbar puncture; thoracentesis; paracentesis; and intubation/mechanical ventilation) was administered to patients or proxies. Handouts describing each procedure were available in the ICU waiting area. Physicians and nurses were introduced to the universal consent form during orientation to the ICU.

Main Outcome Measures

Incidence of informed consent for invasive procedures at baseline and after intervention; whether the patient or proxy provided informed consent; and understanding by the consenter of the procedure as determined by the responses on a questionnaire.

Results

Fifty-three percent of procedures (155/292) were performed after consent had been obtained during the baseline period compared with 90% (308/340) during the intervention period (absolute difference, 37.4%; P<.001). During baseline, the majority (71.6%; 111/155) of consents were provided by proxies. This was also the case during the intervention period in which 65.6% (202/308) of consents were provided by proxies (absolute difference, 6.0%; P = .23). Comprehension by consenters of indications for and risks of the procedures was high and not different between the 2 periods (P = .75).

Conclusions

Invasive procedures are frequent in the ICU and consent for them is often obtained by proxy. Providing a universal consent form to patients, proxies, and health care clinicians significantly increased the frequency with which consent was obtained without compromising comprehension of the process by the consenter.
Energetics and reproductive effort
Authors: Ellison Peter T.
Published: April 2003

Natural selection favors the optimal allocation of energy and other limiting resources to reproduction. Human reproductive physiology displays characteristic patterns that can be viewed as mechanisms that help optimize reproductive effort in the face of environmental energetic constraints. Female ovarian function is particularly sensitive to energy balance and energy flux, resulting in a synchronization of conception with favorable energetic conditions. Reproductive effort during gestation is highly buffered from environmental energetic constraints, but the duration of gestation and final birthweight are both very sensitive to maternal energy availability. Milk production during lactation is relatively buffered from maternal energetic constraints as well, but the duration of lactational amenorrhea is sensitive to the relative metabolic load of lactation. Male gamete production is very insensitive to energetic constraints, but variation in testosterone production in response to both age and longer‐lasting energetic conditions contributes to the modulation of somatic and behavioral aspects of male reproductive effort, aspects that are more energetically costly for a male. There is also new evidence that testosterone may also help to modulate the trade‐off between male parenting and mating effort. Am. J. Hum. Biol. 15:342–351, 2003. © 2003 Wiley‐Liss, Inc.
Adult‐onset asthma and wheeze among irritant‐exposed bleachery workers
Authors: Andersson Eva , Olin Anna‐Carin , Hagberg Stig , Nilsson Ralph , Nilsson Tohr , Torén Kjell
Published: April 2003

Background

Whether new‐onset asthma is associated with irritant exposure is unclear. The aim was to investigate if occupational exposure to irritant gases, especially repeated peak exposure (gassings), increased the risk of obstructive airways disease.

Methods

Data on airway symptoms and exposure among bleachery (n = 101) and paper department workers (n = 314) were collected by a questionnaire. Incidence rates and hazard ratios (HR) (Cox regression) were calculated. Non‐responders were interviewed by telephone.

Results

The incidence rate for adult‐onset physician‐diagnosed asthma among bleachery workers reporting gassings giving rise to respiratory symptoms was 7.6/103 person‐years and for those without gassings 2.2/103 person‐years, compared to 1.0/103 person‐years for paper workers. In a Cox regression model for asthma (n = 12), stratified for sex, HR for gassings were 5.6 (95% confidence intervals (CI) 1.6–20), for hay fever 3.0 (95% CI 0.8–11), and for ever smoking 0.7 (95% CI 0.2–2.4). The same model for adult‐onset wheeze gave HR of 5.2 (95% CI 2.2–12), 1.7 (95% CI 0.6–5.4), and 1.1 (95% CI 0.5–2.7), respectively.

Conclusions

Repeated peak exposure to irritant gases, here studied as gassings in the pulp industry, increased the risk for both adult‐onset asthma and wheeze. Am. J. Ind. Med. 43:532–538, 2003. © 2003 Wiley‐Liss, Inc.
Mastication. IX. Shear‐dependence of degradation on hot mastication
Authors: Mullins L. , Watson W. F.
Published: April 2003

A comparison between the viscosity‐molecular weight relationships for natural rubber degraded in thin films at 130 and 140°C. and on cold and hot mastication indicates a greater similarity of distribution on degradation by the mastication treatments. The hot mastication process is further differentiated from ordinary thermal reactions by the dependence of rate of degradation on the rate of shear. It does, however, differ from cold mastication in being primarily an oxidative‐scission reaction. No differences were detected in the properties of networks prepared from rubbers masticated at high or low temperatures to the same level of degradation.
An apparatus for quantitative gas‐absorption measurements
Authors: Shelton J. Reid , McDonel E. T.
Published: April 2003

An apparatus for quantitative gas‐absorption measurements is described and illustrated with drawings and photograph. A commercially available aluminium block heating unit, adapted to accommodate glass sample tubes, is mounted in an octagonal frame. Gas burets and leveling bulbs are supported on the frame to provide an apparatus for measuring volume changes at a given pressure. Data on rate of heatup and temperature distribution within a sample tube are given. The apparatus has been used primarily for volumetric oxygen‐absorption measurements in studies related to the oxidation of rubber, but it is adaptable to studies involving other materials and other gaseous atmospheres at controlled temperatures. For example, studies have been made with polyethylene, epoxide coatings, and drying oils. The apparatus has also proved useful for curing polyurethanes under moisture‐free conditions and for the vulcanization of rubber in a nitrogen atmosphere.
Studies on orientation phenomena by fiber formation from polymer melts. Part II. Theoretical considerations
Authors: Ziabicki Andrzej
Published: April 2003

The mechanism for orientation of macromolecules through the melt‐spinning of synthetic fibers is analogous to that in polymer solutions flowing in capillaries or in a Couette apparatus. The differences between the two processes, with regard to the velocity field, molecular state, and time dependencies, have been discussed and the differential equations derived to describe the orientation of two extreme molecular models. The coefficients of orientation for fibers consisting of rigid particles (model I) and flexible, coiled chains (model II) have been defined. The specific conditions occuring in fiber‐spinning experiments have been shown, as well as the possibility of applying such experiments to the study of the behavior of macromolecules in the molten state.
The effect of the sorption process on the dynamic rigidity modulus of the wool fiber
Authors: Mackay B. H. , Downes J. G.
Published: April 2003

Using a torsion pendulum, measurements have been made of the dynamic modulus of rigidity of wool fibers during the process of sorbing or desorbing water (from the vapor phase). Anomalous behavior is observed, with low values of rigidity which cannot be accounted for in terms of equilibrium data. It appears that transient stresses occurring during sorption and desorption cause a temporary lowering of the rigidity modulus.
A vibrating reed apparatus for measuring the dynamic mechanical properties of polymers
Authors: Newman Seymour
Published: April 2003

A vibrating reed apparatus for the measurement of dynamic Young's modulus has been constructed. The apparatus utilizes (a) a sensitive capacitance pick‐up to measure displacement of a reed having approximately 0.001 g. of silver painted on the free end of the reed, (b) a clamp assembly which permits placement of the specimen in small temperature‐controlled chambers, and (c) a linear variable differential transformer to facilitate maintenance of constant amplitude (independent of frequency) of the clamped end of the reed.
The measurement of molecular orientation in fibers by acoustic methods
Authors: Moseley W. W.
Published: April 2003

In the present work, the sound velocity in polymeric fibers or film strips is related to a quantitative measure of molecular orientation in the sample. It is shown that this measure of orientation can be calculated from two experimental quantities: the sound velocity in an oriented specimen and the velocity in a randomly oriented sample. Both the oriented and unoriented samples must have the same chemical composition, and both measurements must be made at the same temperature, below the glass transition temperature, Tg. Sound velocities were measured by a pulse technique. This method permitted a continuous measurement of orientation changes during conventional stress‐strain tests without interrupting the tests. In addition, the uniformity of orientation along the length of fibers was measured continuously during windup. Examples of these applications are given, and a comparison is drawn between acoustic and x‐ray measures of orientation.
Loss of antioxidants from polyethylene by evaporation and aqueous extraction
Authors: Hawkins W. L. , Worthington M. A. , Matreyek W.
Published: April 2003

Polyethylene containing various types of antioxidants was either heated in a stream of nitrogen or placed in water maintained at several different temperatures under nitrogen. The polymer was then oxidized to determine how greatly the evaporation or extraction treatment had reduced the antioxidant effectiveness as compared with a control. Polymeric materials and carbon blacks were more completely retained than monomolecular organic compounds. The presence of carbon black did not greatly alter the rate of loss for any of these substances except Santonox, which was almost completely retained.
The mechanical properties of latex‐treated papers
Authors: Heyse W. T. , Sarkanen K. , Stannett V.
Published: April 2003

The effect of the amount and type of latex on the mechanical properties of the paper‐polymer combinations is described in detail. The treatment with latex increases the wet and dry strength properties of the paper considerably, together with improving the folding and tearing resistance. If the polymer in latex is below its film‐forming temperature, however, the beneficial effects of latex treatment are absent. Limitations to varying the rheological properties of plasticpaper combinations are imposed by the comparatively inextensible nature of the paper matrix. Methods of improving the extensibility of paper, including the use of synthetic fiber papers, are discussed, and the time‐dependent nature of the properties are outlined.
Effect of molecular structure on mechanical properties of epoxy resins
Authors: Erich Walter , Bodnar Michael J.
Published: April 2003

The effect of varying the molecular structure of epoxy resins on their mechanical properties when used as adhesives was studied. The work was directed toward preparation of bisphenols of the general formula HOϕCR(R′)ϕOH where R and R′ are either alkyl or alicylic substituents, in which case the benzhydryl carbon is incorporated in a cyclopentane or cyclohexane ring for use in the preparation of glycidyl polyethers having the formula:magnified imagewhere B is the divalent hydrocarbon radical of the bisphenol andnis an integer of the series 0, 1, 2, 3… Preparation of 13 epoxy resins which are liquids at room temperature is described. The effect of varying the structure of the dihydric phenol in the epoxy resin on the strength of adhesive‐bonded joints was determined. The results indicate that relative bonding strengths of epoxy resins synthesized from various bisphenols can probably be attributed to the symmetry and chain length of the substituents attached to the carbon atom connecting the two aromatic nuclei. There is a high correlation between adhesive properties and steric influence of a substituted methyl group. Although the qualitative features of substitution on the central carbon atom are shown to be fairly well understood, there are a number of points that still require clarification. For instance, a more conclusive picture of the effect of branching is desirable. Also, there are uncertainties about the magnitude of the temperature effect and the influence of the substituent on the impact values.
A modified helical spring stress relaxometer for automatic and manual operation
Authors: Dunn J. R. , Scanlan J.
Published: April 2003

A relatively simple and inexpensive automatic and self‐recording apparatus giving good accuracy has been developed for measurement of chemical stress relaxation in elastomer vulcanizates. The apparatus is based on a previously described helical spring relaxometer intended for manual operation. Several improvements applicable to this manually controlled instrument are also described.
The gelation point of alkyd resins
Authors: Jonason M.
Published: April 2003

Using Flory's basic method, an equation is derived for the gelation point of oil‐modified alkyd resins in which account is taken of the different reactivities of the various carboxyl groups. The resultant modified equation is useful when phthalic anhydride is used as the dibasic acid because of the widely differing carboxyl group reactivities which occur in this case. If adipic or isophthalic acid is used as the dibasic acid, the gel point equation deduced by Flory's original method, which takes no account of reactivity differences, may be used. In such a case the difference between the observed and calculated gel point is about 5% when the polyhydric alcohol used is trifunctional and 8–9% when the polyhydric alcohol used is tetrafunctional. The modified gel point equation, applicable when phthalic anhydride is used as the dibasic acid, is shown to predict gel points with similar degrees of accuracy, discrepancies being also greater for alkyds using tetrahydric alcohols than for alkyds using trihydric alcohols. The discrepancy is believed to be due to the occurrence of intramolecular condensation, and it is contended that the degree of such intramolecular condensation in branching systems is proportional to some function of the branch unit functionality.
The permeability of some graft copolymers of polyethylene to gases and vapors
Authors: Myers A. W. , Rogers C. E. , Stannett V. , Szwarc M. , Patterson G. S. , Hoffman A. S. , Merrill E. W.
Published: April 2003

Graft copolymers of polyethylene were prepared by gamma irradiation of polyethylene films immersed in the appropriate monomer. The majority of gas permeability measurements were made by Barrer's high vacuum technique; others were made by measuring volumetric change as a function of time. Sorption isotherms were obtained by using a quartz helix microbalance. Temperature dependent permeability constants have been obtained for permeation of oxygen, nitrogen, and carbon dioxide through styrene, acrylonitrile, and vinylpyridine grafted to low‐density polyethylene. Permeability constants at 25°C. have also been determined as a function of water vapor partial pressure for the above systems. Some values for permeation of carbon dioxide through styrene grafted to high density or linear polyethylene are also given. Organic vapors studied were methyl bromide and isobutene, permeability constants at 0°C. being determined for styrene and acrylonitrile–polyethylene graft copolymers as a function of organic vapor pressure. The data show clearly that permeation through acrylonitrile and vinylpyridine–polyethylene grafts is primarily a diffusion process, while in permeation through polyethylene–styrene grafts, there is also a crystallite solution effect. Percentage grafts varied from 0 to 100 parts monomer per 100 parts by weight polyethylene.
Catalysis of the isocyanate‐hydroxyl reaction
Authors: Britain J. W. , Gemeinhardt P. G.
Published: April 2003

The reaction of toylene diisocyanate (80/20 mixture of 2,4 and 2,6‐isomer) with a secondary hydroxyl‐containing polyoxypropylene triol was studied in the presence of numerous compounds to test their catalytic effect on the reaction. The reaction was studied by determination of the gelation time of the reaction mixture. Many metallic compounds were found to be good catalysts for the isocyanate‐hydroxyl reaction. Compounds in roughly descending catalytic activity are: Bi, Pb, Sn, triethylenediamine, strong bases, Ti, Fe, Sb, U, Cd, Co, Th, Al, Hg, Zn, Ni, trialkylamines, Ce, Mo, V, Cu, Mn, Zr, trialkyl phosphines. Similar gelation tests were made with m‐xylene diisocyanate and the same triol and also with hexamethylene diisocyanate and the triol. In these tests the order of strength of the catalysts was found to be different than when tolylene diisocyanate was used. In decreasing order of activity: Bi, Fe, Sn, Pb, Ti, Sb, strong bases, Co, Zn, triethylenediamine, trialkyl amines. A mechanism is proposed for the way in which a metal compound may catalyze the isocyanate‐hydroxyl reaction. Steric hinderance is suggested to explain the differing catalytic activity observed with tolylene diisocyanate and the unhindered aliphatic diisocyanates.
Measurement of adhesion by a blister method
Authors: Dannenberg Hans
Published: April 2003

An instrument for the measurement of the adhesion of organic coatings has been developed. It is based on the formation of a blister by injecting a liquid (generally mercury) under pressure between the coating and the substrate. The work of detachment, i.e., the energy needed to detach 1 cm.2 of coating, is determined by recording the liquid pressure as a function of the injected volume and computing the area under this curve. Extraneous factors such as deformation of the film and compressibility of the liquid are eliminated through a blank run. The design and operation of the instrument are described, an evaluation of its performance and limitations is given, and examples of its application are presented. The method should be useful for accurate measurement of adhesion of many types of surface coatings to metal and, possibly, to other substrates, as well as for studies of the various factors that influence adhesion.
The resilience of chemically modified cottons. I. Reactions of alkali cellulose and of sodium cellulosates with methylene dibromide
Authors: Lobunez W. , Dusenbury J. H.
Published: April 2003

A study has been made of the reactions of alkali cellulose with methylene dihalides, particularly methylene dibromide. These reactions have involved cotton cellulose in a swollen state, and the treated fabrics have been found to exhibit improved wet crease recovery, with little or no effect on dry crease recovery. The rates of reaction of methylene dibromide with alkali celluloses prepared from potassium hydroxide have been found to be more than double those with alkali cellulosed prepared from sodium hydroxide. The energies of activation in both cases are about 25 kcal./mole, statistically indistinguishable for the two types of alkali, and consistent with the view that covalent bonds are being formed in the course of reaction. The implications and limitations of these results are discussed. Studies have also been made of the reactions of sodium cellulosates with methylene dibromide. In one case, the sodium cellulosates were prepared by reaction of the cellulose with sodium dissolved in liquid ammonia. Here, the reactions appear interesting, but essentially difficult to control. Sodium cellulosates were also prepared by reaction of the cellulose with sodium isoamylate in xylene. When proper care is taken to exclude water from the reaction system, it is found that the reproducibility of duplicate experiments is quite good and that the rate of reaction of the sodium cellulosate with methylene dibromide is much greater than that found for an alkali cellulose prepared from sodium hydroxide.
Environmental stress cracking of polyethylene
Authors: Hittmair P. , Ullman Robert
Published: April 2003

The stress cracking of polyethylene was studied under various experimental conditions, and the importance of the effect of both crystallinity and molecular weight of the polymer was established. Many of the variables were investigated, such as the thermal pretreatment of the sample, temperature of the sample, surface tension, and concentration of the stress‐cracking agent, and the magnitude of the stress. The importance of this test procedure and the relationship that exists between the stress cracking of polymers and between similar problems affecting nonpolymeric systems have been analyzed. Some microscopic studies of stress cracking have also been made.
Design of bonded joints
Authors: Lunsford L. R.
Published: April 2003

Essentially the entire surface of the U. S. Air Force B‐58 supersonic bomber is aluminum‐bonded panel construction. Primary as well as secondary structural bonded panels were designed and manufactured to operate under demanding service conditions which include high stress, subzero temperature, high temperature, and severe acoustical vibration. Smooth surfaces are an additional requirement at subsonic and supersonic speeds. These requirements demanded that bonded joints in the B‐58 be carefully designed and thoroughly evaluated. Joints in the B‐58 were designed by “empirical procedures,” established for a specific adhesive syetem. Large numbers of test panels were required to confirm panel integrity and establish allowables for design. The development and adoption of accurate theoretical technique for predicting joint streqgths has been pursued and can be expected to reduce both the cost and the amount of testing required to achieve reliable deign with adhesives.
Studies on the orientation phenomena by fiber formation from polymer melts. IV. Effect of molecular structure on orientation. Polyethylene and polystyrene
Authors: Ziabicki Andrzej , Kedzierska Krystyna
Published: April 2003

The effect of spinning conditions on fiber birefringence and spinning stress has been studied on high‐pressure polyethylene and two atactic polystyrenes. The general character of the relations observed is similar to that found for polycondensation polymers, but some deviations concerning the effect of deformation ratio have been noted. The x‐ray patterns of the obtained fibers have been presented and discussed. A general interpretation of the observed structural phenomena in the molten linear polymers, based upon the relative crystallization and orientation rates has been given.
The predominant reaction of some fluorinated polymers to ionizing radiation
Authors: Timmerman Robert , Greyson William
Published: April 2003

Polytetrafluoroethylene was irradiated in air, in a vacuum, at elevated temperature, in a nitrogen atmosphere, and in some combinations of these conditions. In all cases the plastic was found to degrade in its structural characteristics. Even the most favorable condition of irradiation (irradiation in vacuo) resulted in a 44% reduction of tensile strength at a dose of 2 Mrad. Polyvinylidene fluoride resisted radiation to at least 100 Mrad effectively. Polyvinyl fluoride was structurally degraded at this dose but retained its structural properties to at least 32 Mrad A cut‐through test under heat, comparing polytetrafluoroethylene with polyvinylidene fluoride and polyvinyl fluoride, showed: (a) Unirradiated polytetrafluoroethylene was most resistant to heat aging. (b) Irradiated and unirradiated polyvinylidene fluoride was inferior to irradiated polytetrafluoroethylene in heat resistance. (c) Irradiated polyvinyl fluoride was superior to irradiated polytetrafluoroethylene; polytetrafluoroethylene at 2 Mrad was inferior to polyvinyl fluoride at 32 Mrad in cut‐through testing. (d) Polyvinylidene fluoride Irradiated and unirradiated and polyvinyl fluoride and irradiated polytetrafluoroethylene all embrittled during heat testing.
Some chemical effects in fatigue cracking of vulcanized rubbers
Authors: Gent A. N.
Published: April 2003

An apparatus is described for studying the fatigue of rubber strips under repeated simple extensions in different atmospheres. The fatigue life is shown to be greatly increased in vacuo for vulcanizates of natural rubber and SBR. The effect of oxidation inhibitors and radical acceptors has been examined; they are found to prolong the life in air, but have little effect in vacuo. The results suggest that a substantial proportion of crack growth in air is due to oxidative deterioration of the rubber at the crack tip, probably initiated by mechanical rupture.