bluuebunny/crossref_metadata_2025 huggingface dataset:
Non-Parametric Estimation of the Age-at-Onset Distribution from a Cross-Sectional Sample
Authors: Mandal S. , Qin J. , Pfeiffer R.M.
Published: December 2022

We propose and study a simple and innovative non-parametric approach to estimate the age-of-onset distribution for a disease from a cross-sectional sample of the population that includes individuals with prevalent disease. First, we estimate the joint distribution of two event times, the age of disease onset and the survival time after disease onset. We accommodate that individuals had to be alive at the time of the study by conditioning on their survival until the age at sampling. We propose a computationally efficient expectation–maximization (EM) algorithm and derive the asymptotic properties of the resulting estimates. From these joint probabilities we then obtain non-parametric estimates of the age-at-onset distribution by marginalizing over the survival time after disease onset to death. The method accommodates categorical covariates and can be used to obtain unbiased estimates of the covariate distribution in the source population. We show in simulations that our method performs well in finite samples even under large amounts of truncation for prevalent cases. We apply the proposed method to data from female participants in the Washington Ashkenazi Study to estimate the age-at-onset distribution of breast cancer associated with carrying BRCA1 or BRCA2 mutations.
United Kingdom criteria for liver transplantation in the setting of isolated unresectable colorectal liver metastases
Authors: Murphy Jamie , Prasad Raj , Menon Krishna ,   the NHS Blood and Transplant Liver Transplantation for Colorectal Liver Metastases Fixed Term Working Unit
Published: December 2022

Aim

Studies have demonstrated that liver transplantation may be an effective treatment for isolated unresectable colorectal cancer liver metastases (CRCLM). Published data suggest that 5‐year survival may be as high as 80%; however, recurrent disease is commonplace. Consequently, the Liver Transplantation for Unresectable Colorectal Liver Metastases Fixed Term Working Unit recommended to the NHS Blood and Transplant Liver Advisory Group that while CRCLM is an appropriate indication for transplantation, selection criteria should be conservative and that it should be undertaken within a clinical service evaluation programme. The aim of this work is to outline the proposed UK selection criteria and follow‐up process for CRCLM transplantation.

Method

Consensus statement by colorectal cancer/liver transplantation patient representatives, experts in colorectal cancer surgery/oncology, liver transplantation surgery, hepatology, hepatobiliary radiology, hepatobiliary pathology and nuclear medicine.

Results

This study provides a comprehensive outline of the inclusion/exclusion criteria for referral in the UK. Furthermore, the referral framework is also explained. Pretransplant assessment criteria for listing/delisting are outlined. Finally, the oncology‐specific outcome measures posttransplant are described.

Conclusion

It is anticipated this service will begin in December 2022. A series of educational events for the referrers and transplant units will be arranged throughout 2023 to highlight CRCLM as a newly accepted UK indication for transplantation. A national audit will be undertaken to identify patients currently on treatment who meet the criteria for transplant. Data will be collected in a national registry and reviewed on an ongoing basis to confirm the safety of this treatment and to determine if the inclusion criteria require revision.
Acetylation of nuclear receptors in health and disease: an update
Authors: Ashton Anthony W. , Dhanjal Harpreet K. , Rossner Benjamin , Mahmood Huma , Patel Vivek I. , Nadim Mohammad , Lota Manpreet , Shahid Farhan , Li Zhiping , Joyce David , Pajkos Matyas , Dosztányi Zsuzsanna , Jiao Xuanmao , Pestell Richard G.
Published: December 2022

Lysine acetylation is a common reversible post‐translational modification of proteins that plays a key role in regulating gene expression. Nuclear receptors (NRs) include ligand‐inducible transcription factors and orphan receptors for which the ligand is undetermined, which together regulate the expression of genes involved in development, metabolism, homeostasis, reproduction and human diseases including cancer. Since the original finding that the ERα, AR and HNF4 are acetylated, we now understand that the vast majority of NRs are acetylated and that this modification has profound effects on NR function. Acetylation sites are often conserved and involve both ordered and disordered regions of NRs. The acetylated residues function as part of an intramolecular signalling platform intersecting phosphorylation, methylation and other modifications. Acetylation of NR has been shown to impact recruitment into chromatin, co‐repressor and coactivator complex formation, sensitivity and specificity of regulation by ligand and ligand antagonists, DNA binding, subcellular distribution and transcriptional activity. A growing body of evidence in mice indicates a vital role for NR acetylation in metabolism. Additionally, mutations of the NR acetylation site occur in human disease. This review focuses on the role of NR acetylation in coordinating signalling in normal physiology and disease.
High‐purity isolation platelets by gradient centrifugation plus filtration
Authors: Jin Jia , Shao Yilin , Zhang Jian , Cao Junning , Tao Zhonghua , Hu Xichun
Published: December 2022

Introduction

Platelets can be used as a liquid biopsy source to provide rapid, up‐to‐date, and relevant information on tumor pathology and treatment response. However, there is still a lack of high efficiency methods for platelet isolation with high purity.

Methods

Three platelet isolation methods were evaluated by platelet recovery and purity. The platelet inhibition cocktail (PIC) was added into peripheral blood, or was not allowed to access the effect of the platelet activation. The CD61, CD45, and CD62P labelled platelets, leukocytes and activated platelets were detected by flow cytometry. Quantitative polymerase chain reaction (qPCR) and next‐generation sequencing (NGS) were employed to determine the gene expression levels. A time‐dependent experiment combined with qPCR was used to determine the time limit for platelet isolation at room temperature.

Results

Compared to the gradient centrifugation alone, and gradient centrifugation plus filtration and magnetic beads separation, gradient centrifugation plus filtration was the preferred method for more efficient and high‐purity platelet isolation, with a recovery rate of 9.1% and a purity of 99.98%. Furthermore, there was no difference in platelet activation level, regardless of whether PIC was used. Moreover, the rate of platelet RNA degradation did not differ when platelets were isolated within 48 h of blood collection.

Conclusion

Gradient centrifugation plus filtration at room temperature within 48 h of blood collection, without PIC, is a novel protocol with high recovery and purity rate to isolate platelets.
Oral hygiene interventions to prevent ventilator‐associated pneumonia: A network meta‐analysis
Authors: Garegnani Luis Ignacio , Giménez María Lucía , Escobar Liquitay Camila Micaela , Franco Juan Victor Ariel
Published: December 2022

Background

Ventilator‐associated pneumonia (VAP) is a common complication in ventilated patients. The endotracheal tube acts as a conduit for oral cavity pathogenic bacteria into the lungs due to an imperfect cuff seal. Oral hygiene is designed to remove plaque and debris where bacteria multiply, reducing the risk of ventilator‐associated pneumonia.

Aims

To assess the comparative effects of oral hygiene agents and modalities on VAP incidence in critically ill mechanically ventilated patients and to assess their relative ranking according to their effects.

Study Design

Systematic review and network meta‐analysis (PROSPERO registration CRD42021259690). We retrieved randomized controlled trials using oral hygiene procedures from a recent Cochrane review and updated the search to December 2021.

Results

We included 30 RCTs with 3980 participants. Some interventions, such as miswak and nanosil, may result in a large decrease in VAP incidence (miswak RR 0.05, 95% CI 0.00–1.21; nanosil RR 0.08, 95% CI 0.01–0.88), but some confidence intervals include substantial benefits and harms. Powered toothbrushing and manual toothbrushing may result in a large decrease in VAP incidence (powered toothbrushing RR 0.55, 95% CI 0.30–1.00; manual toothbrushing RR 0.65, 95% CI 0.40–1.04); however, the confidence intervals may indicate little to no significant difference. The certainty of the evidence was mostly low due to the small sample size and risk of bias.

Conclusions

Low‐certainty evidence indicates that miswak and nanosil may reduce VAP incidence. Moreover, toothbrushing may also reduce VAP incidence and mortality. High‐quality RCTs are needed to establish the relative effectiveness of these interventions.

Relevance to Clinical Practice

Several oral agents may decrease VAP incidence and mortality. Powered toothbrushing and manual toothbrushing may decrease VAP incidence and mortality.
Fibroblast growth factor 23‐Klotho and mineral metabolism in the first year after pediatric kidney transplantation: A single‐center prospective study
Authors: Kubota Mai , Hamasaki Yuko , Hashimoto Junya , Aoki Yujiro , Kawamura Takeshi , Saito Akinobu , Yuasa Rena , Muramatsu Masaki , Komaba Hirotaka , Toyoda Masao , Fukagawa Masafumi , Shishido Seichiro , Sakai Ken
Published: December 2022

Background

The role of fibroblast growth factor 23 (FGF23) levels in mineral metabolism before and after kidney transplantation in pediatric patients is poorly understood.

Methods

We prospectively evaluated 24 patients under 18 years of age (4.5 [3.3–9.8] years) who underwent living kidney transplantation between July 2016 and March 2018, and measured intact FGF23 and serum αKlotho levels, and other parameters of mineral metabolism before and after transplantation (Day 7, 1 and 4 months, and 1 year). Relationships between parameters were examined by linear analysis.

Results

FGF23 level was 440.8 [63.4–5916.3] pg/ml pre‐transplant and decreased significantly to 37.1 [16.0–71.5] pg/ml at Day 7 post‐transplant (−91.6%, p < .001). Thereafter, it remained at normal levels until 1 year. αKlotho level was 785 [568–1292] pg/ml pre‐transplant and remained low at Day 7 and 1 month post‐transplant, with an increasing trend at 4 months. Post‐transplant phosphorus levels were significantly decreased compared with pre‐transplant, with a lowest level of 1.7 [1.3–2.9] mg/dl, −5.7 [−6.8, −3.8] SD at Day 4, followed by gradual recovery. Phosphorus levels and the ratio of tubular maximum phosphate reabsorption were significantly and negatively associated with pre‐transplant FGF23 until 4 months of post‐transplant. Pre‐transplant αKlotho was negatively associated with pre‐transplant FGF23 but not FGF23 or other parameters after transplantation.

Conclusion

FGF23 in pediatric kidney transplant patients decreased rapidly after transplantation and associated with post‐transplant hypophosphatemia and increased phosphorus excretion. Post‐transplant αKlotho was low early post‐transplant but tended to increase subsequently. Post‐transplant αKlotho was unaffected by pre‐transplant FGF23 or other factors, suggesting pre‐transplant chronic kidney disease status has no effect.
B2B online sales pushes: Whether, when, and why they enhance sales performance
Authors: Kanuri Vamsi K. , Habel Johannes , Chaker Nawar N. , Rangarajan Deva , Guenzi Paolo
Published: December 2022

Business‐to‐business (B2B) sellers are increasingly transitioning to hybrid sales structures, by augmenting an in‐person field sales force with a direct online channel. During this transition, sellers frequently experience a cold‐start problem, wherein existing customers are either not acquainted with the online channel or unconvinced of its usefulness and are therefore reluctant to adopt it. To overcome the cold‐start problem, B2B sellers are increasingly relying on online sales pushes, which are efforts to encourage salespeople to nudge customers to adopt the online channel for certain buying tasks. Yet, because salespeople may fear that the online channel adoption jeopardizes the very relationships that they painstakingly built, the salespeople's compliance with an online sales push remains unclear. To glean insight into this dilemma, we empirically investigate an online sales push's impact on salesperson effort (re)allocation and sales performance. Based on an econometric analysis of archival data from a B2B seller and a scenario‐based experiment, we conclude that salespeople generally tend to comply with an online sales push because it frees up their time and allows them to pursue new selling opportunities that have the potential to increase their compensation. The results also indicate that following an online sales push, salespeople expend their effort based on a customer's online proclivity and potential prior to the push. Moreover, the effort expended varies over time and across communication channels. Additionally, the analysis reveals (a) asymmetric carryover and cross‐channel effects of communication effort and sales performance and (b) asymmetric synergistic effects of communication effort on sales performance.
Optimized identification of earlywood and latewood stiffnesses in loblolly pine in simulated experiments
Authors: Considine John M. , Bechle Nathan J. , Pierron Fabrice , Krestschmann David E.
Published: December 2022

Knowledge of local mechanical behaviour of wood is especially important as silvicultural practices are modified to allow wood to compete as a relevant material in high technology applications. Challenges associated with identification of local mechanical behaviour have resulted in simplified test geometries designed to determine one or two constitutive parameters. The objective of this work was to design and simulate an entire experiment developed to simultaneously identify the earlywood and latewood orthotropic stiffnesses in loblolly pine in a single specimen and load geometry. The virtual experiment was capable of evaluating optimal orthotropy orientation for reduced identification errors and indicating most favourable choices for data smoothing filters and identification methodology. Additionally, certain ring spacing and latewood percentages were shown to produce large errors, but those combinations are unlikely to occur naturally. The simulation was able to identify
, and
with approximately
error; the
error was larger with more scatter. The methodology presented here contributes to the best practices available for heterogeneous stiffness identification.
Differential soil acidification caused by parent materials and land‐use changes in the Pearl River Delta region
Authors: Wen Hui‐Ying , Wu Hua‐Yong , Dong Yue , Feng Wen‐Juan , Lu Ying , Hu Yue‐Ming , Zhang Gan‐Lin
Published: December 2022

Soil acidification occurs widely across the world, which has been partly attributed to land‐use change. However, measureable effect of land‐use change as well as parent materials on soil acidification remains poorly understood. Here, a typical area with intensive land‐use change in the Pearl River Delta of China was chosen for this study. Topsoil (0–20 cm) and subsoil (20–40 cm) samples (n = 169) under different land uses (paddy fields, vegetable lands and orchards) and parent materials (granite and alluvial sediment) were collected in 2020. Soil pH, exchangeable base cations, exchangeable acidity and pH buffering capacity were measured to evaluate the status of soil acidification. The change of soil pH over the last 15 years was evaluated via comparing with historical data (n = 329) in 2005. The results showed a higher exchangeable acidity and lower pH buffering capacity and exchangeable base cations of soils derived from granite compared with soils derived from alluvial sediment in 2020. In the last 15 years, significant soil acidification under different parent materials was observed under vegetable lands and orchards but not paddy fields. Faster pH decline was found under land‐use change from paddy fields compared with the unchanged vegetable lands or orchards. Furthermore, stronger acidification under the same land‐use change was observed for soils derived from granite compared with soils derived from alluvial sediment. These results indicate that land‐use change induced soil acidification is dependent on parent materials. This study implies that cropping management such as suitable rotation operation may slow soil acidification, and measures including straw returning may ameliorate acidified soils.
Involvement of SlSTOP1 regulated SlFDH expression in aluminum tolerance by reducing NAD+ to NADH in the tomato root apex
Authors: He Qiyu , Jin Jianfeng , Li Pengfei , Zhu Huihui , Wang Zhanqi , Fan Wei , Yang Jian Li
Published: December 2022

Formate dehydrogenase (FDH; EC 1.2.1.2.) has been implicated in plant responses to a variety of stresses, including aluminum (Al) stress in acidic soils. However, the role of this enzyme in Al tolerance is not yet fully understood, and how FDH gene expression is regulated is unknown. Here, we report the identification and functional characterization of the tomato (Solanum lycopersicum) SlFDH gene. SlFDH encodes a mitochondria‐localized FDH with Km values of 2.087 mm formate and 29.1 μm NAD+. Al induced the expression of SlFDH in tomato root tips, but other metals did not, as determined by quantitative reverse transcriptase‐polymerase chain reaction. CRISPR/Cas9‐generated SlFDH knockout lines were more sensitive to Al stress and formate than wild‐type plants. Formate failed to induce SlFDH expression in the tomato root apex, but NAD+ accumulated in response to Al stress. Co‐expression network analysis and interaction analysis between genomic DNA and transcription factors (TFs) using PlantRegMap identified seven TFs that might regulate SlFDH expression. One of these TFs, SlSTOP1, positively regulated SlFDH expression by directly binding to its promoter, as demonstrated by a dual‐luciferase reporter assay and electrophoretic mobility shift assay. The Al‐induced expression of SlFDH was completely abolished in Slstop1 mutants, indicating that SlSTOP1 is a core regulator of SlFDH expression under Al stress. Taken together, our findings demonstrate that SlFDH plays a role in Al tolerance and reveal the transcriptional regulatory mechanism of SlFDH expression in response to Al stress in tomato.
Transmission Systems for Marine Propulsion Gas-Turbine Power Plants
Authors: Hammond W. E.
Published: December 2022

The author discusses various transmission systems now available which might be used in connecting a gas-turbine power plant to the propeller of a merchant ship. The major problems to be met by any transmission system are those relating to reversibility and maneuverability. It is concluded that alternating-current electric drive, mechanical reversing gears, and mechanical reduction gear with the controllable and reversible pitch propeller offer acceptable solutions to the problems.
Fuels Performance at Port Washington Station
Authors: Pollock W. A.
Published: December 2022

This paper contains recent operating data, a discussion of relevant design features, and information comparing prewar and postwar coals as affecting operation of the Port Washington Station of the Wisconsin Electric Power Company. In order to make the report complete, fuels and station performances are presented.
Performance Criteria for Positive-Displacement Pumps and Fluid Motors
Authors: Wilson W. E.
Published: December 2022

The comparison of performance characteristics of positive-displacement pumps and fluid motors on the basis of dimensionless performance coefficients and dimensionless efficiency curves is presented as a substitute for the present methods. It is shown that the coefficients describe performance adequately and are subject to significant interpretation in terms of the geometry of the unit. The dimensionless efficiency curve is shown to have advantages in presenting a wide range of data and in prediction of performance characteristics under any specified operating conditions.
How Forging Acts to Enhance Metal Properties
Authors: Dixon E. O. , Foley E. J.
Published: December 2022

Heretofore unrecognized effects of high impact pressures developed by forging steel in closed dies have been studied. Mechanical properties are compared for conditions of varying restraint to metal flow. Forging tests have been devised to permit analysis of impact pressure with and without accompanying plastic flow as separate effects. High impact pressures developed in drop forging contribute substantially to the improvement in ductility and notched-bar toughness. This is demonstrated under conditions of negligible plastic flow.
Automatic Control of Turbojet Engines
Authors: Cody C. S.
Published: December 2022

This paper presents the requirements for automatic control of a turbojet engine in order to meet the needs of military aviation and to realize the full operational performance of the engine. The author describes how these requirements were established, and outlines the recommended approach to the design of an optimum engine power control.
Visual Passenger Comfort
Authors: Stevens Brooks
Published: December 2022

The author outlines the problem confronting the railroad-train designer in providing the comfort and beauty which the passenger has come to expect, and which is necessary to attract his patronage in the highly competitive field of modern transportation. The over-all design conception is discussed, with decorative treatments described of such famous trains as the Olympian-Hiawathas. The author’s conception is given of the facilities and styling of passenger cars of various types which will make up the “train of tomorrow.”
A New Approach to the Design of Dynamically Loaded Extension and Compression Springs
Authors: Johnson Curt I.
Published: December 2022

This paper contains formulas and derivations of a design procedure for dynamically loaded extension and compression springs which permits straightforward solutions to spring problems with minimum assumptions. It is based upon a new method of graphical representation of spring characteristics and includes the following equations Ce=GKπSs×1Y−1+T for extension springs, or Cc=GKπSs×1Y−Tc for compression springs. Qe=P(Y−1+T) for extension springs, or Qc=P(Y−Tc) for compression springs d=8C3QG where C is the spring index, Q is the load constant, and d is the wire diameter as determined either mathematically or graphically. These items are utilized with “spring proportion tables” (Table 1), for convenient solutions to problems. This paper also describes a method of cataloging stock springs based upon a new graphical representation.
Thermal Contact Resistance of Laminated and Machined Joints
Authors: Brunot A. W. , Buckland Florence F.
Published: December 2022

Values of thermal contact resistance are reported for two types of joints: (1) the joint between two blocks of laminated steel, either in direct contact or separated by cement or shims of steel, aluminum, or aluminum foil; (2) the joint between two blocks of cold-rolled steel with various surface finishes. The resistance as measured amounts to 0.3 to 8 in. of additional material, depending upon the configuration. Results are also given in terms of contact resistance.
Thermal Resistance Measurements of Joints Formed Between Stationary Metal Surfaces
Authors: Weills N. D. , Ryder E. A.
Published: December 2022

Results are presented of the measurements of the thermal resistance of dry and oil-filled joints formed between two flat surfaces of various metals. Experimental apparatus consisted of two test blocks, 3 in. diam × 3 in. long, stacked axially on one another, in contact with an inductively heated copper block at one end and with a water-cooled copper block at the other, all placed between the platens of a hydraulic press. The thermal conductance of the joint formed between the two test blocks was obtained from the measured heat flow and temperature gradient through the blocks and studied as a function of temperature, pressure, and surface finish. The temperature at the joint ranged from 300 to 500 F, the thermal current across the joint from 10,000 to 130,000 Btu/(hr) (sq ft), the temperature drop across the joint from 1 to 100 F, and the pressure on the joint from 2 to 8000 psi. The thermal resistance, interpreted by analogy to the concept of electrical spreading resistance, is decreased by increasing the temperature and pressure, by the inclusion of oil, or by plating the surfaces with a soft metal.
Operating Characteristics and Requirements of Drawworks Brake Equipment
Authors: De La Mater R. G.
Published: December 2022

In this paper an analysis is made of the operating characteristics, capacity, and limitations of the mechanical friction brakes and of the hydraulic and electric types of supplemental dynamic brakes used on drawworks. Consideration is then given to the relative advantages and disadvantages of various methods of drawworks operation while running in the drill pipe. The speed-load characteristics of the drawworks, for a preferred method of operation, are then compared with the speed-capacity characteristics of the several available brake systems. Consideration is also given to the requirements of the driving means for supplemental dynamic brakes.
Automatic Drilling Feed Controls for Rotary Drilling Rigs
Authors: Crake W. S.
Published: December 2022

A considerable amount of detailed study and thought, design, and field testing of various means of achieving the desired results has gone to bring work on drilling controls to their present status. Up to the present, however, the results of this study and work have not been recorded except in improvement in machine performance. This paper is not primarily intended to be an evaluation of the results of automatic-controlled versus hand-controlled drilling, but it is felt by the author that the subject is of major importance in reducing drilling costs, and that all those factors which have been considered, and the analyses of the problems, should be placed on record. Others may wish to extend or revise the analyses and build or purchase similar devices, and this report will, it is hoped, save them from having to duplicate the efforts of the past few years and to determine if the machines designed or offered have the required characteristics.
Pressure Surges and Vibration in Reciprocating-Pump Piping
Authors: Squire J. W.
Published: December 2022

In the early days of the petroleum industry in America, the long pipe lines through which oil was pumped gave constant trouble from bursts caused by “shock” pressures. The author traces pump and other developments through the years which were intended to reduce the surge problem. Practically all solutions were based upon the use of air chambers, equalizer lines, or otherwise designing piping to prevent these surges from becoming dangerous. With the pumps in use today, pressure swings of 50 to 60 per cent of the mean pressure are experienced. Steps taken to so arrange the flow in the pump that these pressure surges are held within a reasonable percentage of the theoretical value are outlined in the paper. These consist mainly of changes in the pump-valve system, which the author describes at some length, supported by mathematical and test data.
Anisotropic Plastic Flow
Authors: Fisher J. C.
Published: December 2022

The mathematical theory of plasticity has been generalized to apply to plastically anisotropic materials. The anisotropic flow theory has been shown to reduce to the resolved shear stress - shear strain relationship for single crystals, and to the distortion energy theory for isotropic polycrystals. Experimental data concerning the plastic flow of anisotropic polycrystalline aluminum indicate that the predictions of the anisotropic flow theory are in good agreement with experiment, and are significantly better than the predictions of the distortion energy theory. As plastic anisotropy is the rule rather than the exception, caution is indicated in interpreting the results of combined stress tests by means of the distortion energy theory.
The Laminar-Film Hypothesis
Authors: Miller Benjamin
Published: December 2022

The laminar-film hypothesis which plays so prominent a part in current heat-transfer literature grew out of a formula relating the pressure gradient along a tube through which a fluid is passing to the rate of heat transfer between the tube and the fluid. Perry derived this formula by combining Péclet’s idea that heat transferred between a body of fluid in violent motion and a bounding solid must flow by conduction through a fluid film at the boundary, with Reynolds analogy between heat convection and momentum convection. Prandtl and later Taylor identified the surface film, invented to explain heat-transfer findings, with a layer of fluid assumed in fluid mechanics to move in laminar flow along the tube wall while the body of fluid forms a turbulently moving core, and they modified Perry’s formula accordingly. Stanton pointed out that the film thickness could be calculated by the modified formula from heat-transfer measurements, and that proof by velocity measurements that there was indeed a laminar film having the calculated thickness would substantiate the hypothesis; but his experiments showed only that there was a region characterized by velocity gradients intermediate between those in the central part of the tube and those calculated for laminar flow. Eagle and Ferguson offered a formula having a term for the intermediate zone as well as one for the laminar film and one for the turbulent core, and calculated the numerical constants from their heat-transfer measurements. Von Kármán adopted the three-zone scheme, but obtained his numerical constants from a velocity distribution published by Nikuradse. If the velocity distribution used by von Kármán had actually been determined experimentally by Nikuradse, the laminar-film hypothesis would be strongly supported, but Nikuradse’s experimental results were inconsistent with the laminar-film hypothesis; having more faith in the hypothesis than in his experimental results, Nikuradse adjusted the results to make them seem to be in accord with the hypothesis, and published the adjusted results as well as the unadjusted, without explaining the discrepancy.
A Critical Review of Skin-Friction and Heat-Transfer Solutions of the Laminar Boundary Layer of a Flat Plate
Authors: Rubesin M. W. , Johnson H. A.
Published: December 2022

A review is made of existing literature concerned with the analytical investigation of the velocity and temperature distributions in the boundary layers of a heated (or cooled) flat plate. The plate is postulated infinitely thin and is parallel to a uniform fluid stream. The more recent solutions include the combined effects of frictional dissipation and variable fluid properties. Only the results pertaining to the transfer phenomena occurring at the plate surface are included, i.e., skin drag and over-all heat transfer; the individual temperature and velocity distributions leading to these results are omitted.
Supersonic Convective Heat-Transfer Correlation From Skin-Temperature Measurements on a V-2 Rocket in Flight
Authors: Fischer W. W. , Norris R. H.
Published: December 2022

Coefficients of convective heat transfer have been evaluated by analysis of the skin-temperature measurements made at several points on the nose of a V-2 (German A-4) rocket during flight in New Mexico. On one side, the surface of the nose was smooth but on the other side, 4 in. from the nose tip, a transverse ridge about ⅛ in. high, was purposely provided as a turbulence promoter.

The test results are compared in dimensionless form with various proposed correlations for both laminar and turbulent conditions of the boundary layer. The test results, thus correlated, seem to justify the following conclusions: (1) Boundary-layer transition seems to be more dependent, at supersonic speed, on Mach number than on Reynolds number. (2) The theoretical heat-transfer correlation for a laminar layer is confirmed by the appropriate sets of test points to the estimated order of accuracy of the test. (3) For turbulent layer conditions, the subsonic correlation for a flat plate provides better agreement with the supersonic test results than does Eber’s correlation, but there still remains a range of uncertainty as to the best choice of temperature for evaluation of the air properties.
An Evaluation of the Performance of Thirty-Three Residential-Stoker Coals
Authors: Purdy J. B. , Nelson H. W.
Published: December 2022

This paper is based upon experience gained from evaluation tests, sponsored by individual coal producers during the past 12 years, to determine the suitability of various coals for use in residential underfeed stokers of the clinkering type. The conclusions reached through the evaluation tests are in general agreement with the marketing experiences of the producers in the field. Comparisons are also made between the characteristics of the coals as determined by the evaluation tests and data determined by standard laboratory-test methods. Correlation in this regard was not good.
Elements of Graphical Solution of Water-Hammer Problems in Centrifugal-Pump Systems
Authors: Stepanoff A. J.
Published: December 2022

Since publication of the “Symposium on Water Hammer,” in 1933, considerable progress has been made abroad in the development of the graphical method of solution of water-hammer problems. Although based upon the same fundamental relationships as the analytical solutions, the graphical method does not require an exact knowledge of the theoretical background and, at the same time, it gives a clear mental pattern of the events which enables one to use it with confidence for solution of practical problems. Early studies of water-hammer problems were carried out almost entirely in connection with water-turbine applications. Water-hammer problems in the centrifugal-pump field are more numerous and varied, but owing to the smaller size of units, the effects of water hammer were learned by experience, damage being repaired at a relatively low cost. Centrifugal-pump designers and users are little familiar with water-hammer theory. Fear of involved mathematical treatment has been a major factor to such neglect. The author attempts to present the water-hammer theory, and the graphical method of solution in its simplest terms. This will enable a pump engineer to recognize the conditions leading to water hammer, to estimate the possible maximum pressure rise and, when necessary, to provide means to reduce the pressure rise to a safe limit.
Film-Pressure Distribution in Grease-Lubricated Journal Bearings
Authors: Cohn Gunther , Oren Jess W.
Published: December 2022

Measurements of the pressure developed in the load-carrying film of a grease-lubricated journal bearing show that grease can operate under hydrodynamic conditions. In a testing fixture, constructed for the purpose, the magnitude and the distribution of that pressure is investigated using a cup grease under conditions of copious feed. The graphical analysis of the results shows a grease dome similar to that of oil, but flatter and extending over a larger arc.
Viscosities and Densities of Lubricating Fluids From −40 to 700 F
Authors: Murphy C. M. , Romans J. B. , Zisman W. A.
Published: December 2022

The viscosities and densities of a large group of high-boiling synthetic and petroleum fluids were investigated over a wide range of temperatures. These were selected because of their promise for use at extreme temperatures or their ability to supply fundamental data for viscometry and lubrication. The variation of density with temperature was practically linear over the range investigated. The ASTM viscosity-temperature chart, extended from −100 to 700 F for this work, proved very satisfactory for analysis of the data obtained. Deviations from linearity at the extreme temperatures were studied and classified and nearly all could be explained on the basis of certain physical or chemical transformations shown to occur at the extreme temperatures The linear portions of the graphs are explained qualitatively in terms of the ability of many types of linear molecules to coil as helices. Convexity at high temperatures is believed general, caused by the disappearance of the helical configuration under conditions of violent thermal agitation.
Comparison of High-Temperature Alloys Tested as Blades in a Type B Turbosupercharger
Authors: Stewart W. C. , Ellinghausen H. C.
Published: December 2022

The authors describe briefly a series of jet tests, utilizing gas produced from the combustion of Diesel fuel oil, as a means for comparing the resistance of a number of high-temperature alloys to hot-gas impingement. The deficiencies of this method for simulating conditions in a gas turbine are discussed. The paper is concerned principally with comparative tests of a number of high-temperature alloys when tested in the form of blades in a Type B turbosupercharger. The test rotor contains 142 blades, representing 12 different alloys. Both wrought and precision-cast blades are included. Tests were made at eight temperatures, ranging from approximately 1200 to 1500 F, test runs at each temperature being of 50 to 150 hr duration, except in the case of the 1500 F test run, which was continued for 1000 hr. After several of the test runs, measurements were made to determine the amount of permanent extension in the blades and disk. The extension of the blades and disk accompanying progressively higher testing temperatures is shown graphically. A procedure for correlating the metal temperature of the blades with that of the combustion gas in the nozzle chamber of the supercharger is described.
The Applicability of Ceramics and Ceramals as Turbine-Blade Materials for the Newer Aircraft Power Plants
Authors: Bobrowsky A. R.
Published: December 2022

Ceramic and ceramal materials have been investigated for use as turbine-blade materials for aircraft gas turbines. Tensile, flexure, thermal-shock, and oxidation data for these materials at temperatures up to 2400 F are presented. These data are discussed with respect to applicability for turbine use. Results of turbine-blade operation at the NACA Cleveland laboratory are given.
Changes in Internal Damping of Gas-Turbine Materials Due to Continuous Vibration
Authors: Wilkes G. B.
Published: December 2022

A pneumatically driven elevated-temperature fatigue machine and its control are described briefly. The use of this machine to determine qualitatively the initial damping as well as the changes in damping of the test specimen during vibration are discussed. The variation in high-stress initial damping versus temperature has been determined qualitatively on four high-temperature alloys. The elevated-temperature damping has been checked qualitatively during continuous vibration at high stresses. Two materials with extremely high initial damping tended to lose a large portion of it with time. The other materials showed damping changes of as high as 25 per cent with some increasing and some decreasing. Most of the data were taken below the fatigue limit and at temperatures of 1200 F, 1350 F, and 1500 F.
Energy in the Engine Exhaust
Authors: Schweitzer P. H. , Tsu T. C.
Published: December 2022

The maximum amount of energy which an ideal turbine can recover from the exhaust gas of an engine is the same as the additional energy obtainable from an ideal, complete-expansion piston engine. This energy, known as the convertible blowdown energy, is equal to the tail triangle of the p-v diagram. A chart is presented for the quick determination of the convertible blowdown energy for exhaust release pressures between 10 and 1000 psia, exhaust release temperatures between 0 and 4000 F, and altitudes between sea level and 40,000 ft.
High-Pressure Boilers With Reheaters
Authors: Rowand W. H. , Raynor A. E. , Gilg F. X.
Published: December 2022

When power generating equipment is designed to operate within the reheat steam cycle, the steam generating unit includes a reheat section in which partly expanded steam, returned from the turbine, is reheated before final expansion takes place. Reheat boiler units which have been in service for more than 20 years are described, together with some modern high-pressure high-temperature units. Comparison of reheat with nonreheat steam generating units to generate the same kilowatt capacity at the same boiler efficiency and draft loss is shown, together with estimated cost increase of the reheat boilers.
Modern Reheat Boilers
Authors: Patterson W. S.
Published: December 2022

This paper gives a brief historical résumé of reheat progress followed by a discussion of the design factors which dictate the size, shape, and proportions of a large reheat steam generator. A few typical installations are illustrated and discussed, and general comments on operational procedures are included.
Chemical Cleaning of Heat-Exchange Equipment
Authors: Loucks C. M. , Groom C. H.
Published: December 2022

The use of chemical solvents in cleaning heat-exchange equipment is described on the basis of the types of deposits, the solvents available, and the metals encountered. The application of the solvents is discussed, and a number of case histories are described, illustrating chemical cleaning in various industries.
Cleaning Tubular Heat Exchangers
Authors: Dougherty P. F. , Brooks C. H.
Published: December 2022

A discussion is presented covering various methods available for cleaning tubular beat-transfer equipment, with particular emphasis on the use of an emulsifying oil for “in-place” cleaning, and on the use of sandblasting. The relative merits of the in-place and the mechanical methods are outlined as well as the factors to be considered in selecting a particular procedure for a given application.
Rates of Fouling and Cleaning of Unfired Heat-Exchanger Equipment
Authors: Weiland J. H. , McCay R. C. , Barnes J. E.
Published: December 2022

This paper presents heat-exchanger performance data and describes exchanger cleaning procedures during the period 1943–1947 at the Port Arthur Works of The Texas Company. The performance data are presented in the form of tables and graphs which show the rates of over-all heat-transfer and exchanger fouling, and the changes in these rates after bundle cleansing.
Discussion: “The Fouling and Cleaning of Surfaces in Unfired Heat Exchangers” (John, A., Loucks, C. M., Groom, C. H., Campobasso, J. J., Latham, Jr., Allen, Dougherty, P. F., Brooks, C. H., Butler, R. C., McCurdy, Jr., W. N., Weiland, Jr., J. H., McCay, R. C., Barnes, J. E., and Bethon, H. E., 1949, Trans. ASME, 71, pp. 825–869)
Authors: Bergelin O. P.
Published: December 2022

This report summarizes the proceedings of the panel discussion meeting of the Symposium on Folding and Cleaning of Heat Exchange Equipment. Fouling in water circuits, in steam power plants, in marine power plants, in the process industries, and the effect of fouling upon the design of equipment are covered by the papers of the panel leaders. Topics brought up during the general discussion include fouling by calcium-sulphate scale, the suitability of certain “cleanliness factors” used in marine-equipment specifications, the use of additives to reduce fouling by fuel oil, and the effect of manufacturing tolerances and design upon the rate of fouling.
Thermodynamic Properties of Oxygen, Nitrogen, and Air at Low Temperatures
Authors: Claitor L. C. , Crawford D. B.
Published: December 2022

The proper engineering design of modern low-pressure tonnage oxygen plants requires data on the thermodynamic properties of oxygen, nitrogen, and air that are more accurate than those previously available from charts. In this paper, new temperature-entropy diagrams of suitable scale are presented for these materials over a range of temperatures and pressures adequate for the purpose. These diagrams are calculated from literature data on zero-pressure heat capacity and latent heats of vaporization, and from a reduced equation of state which was obtained from a correlation of literature data on volumes, Joule-Thomson coefficients, and velocity-of-sound measurements.
Zero-Pressure Thermodynamic Properties of Carbon Dioxide
Authors: Gratch Serge
Published: December 2022

In this report are presented tables of the principal thermodynamic properties of carbon dioxide along the zero-pressure isobar in the range 100 to 5000 deg R at the intervals indicated by the numbers in parentheses as follows: 100(5)130(10)240(20)500(50)1000(100)2000(200)5000. The data have been computed by the methods of quantum statistical mechanics from best available information regarding (a) the general physical constants, (b) the spectroscopic constants for carbon dioxide, (c) the isotopic weights of carbon and oxygen, (d) the relevant abundance ratios. The computations were carried out in the University of Pennsylvania Thermodynamics Research Laboratory under Project G-12. Computational accuracy well beyond present physical accuracy has been maintained for practical reasons. It is believed that the tables given herein should supersede all previous ones. Although the estimated uncertainties of the values tabulated are still somewhat larger than those for some of the simpler molecules, they are probably small enough for most engineering applications. The calculated values are in fair agreement with those obtained from calorimetric and acoustic-velocity measurements.
Mechanical Vibration of Piping Induced by Gas-Pressure Pulsations
Authors: Baird R. C. , Bechtold I. C.
Published: December 2022

The generation and nature of gas-pressure pulses from reciprocating compressor action are described, together with the propagation of such pulses through pipe lines. The means whereby pulse energy is converted to mechanical vibration is discussed by the aid of analogous mechanical, acoustical, and electrical oscillatory systems. The economic importance of minimizing vibration in compressor and compressor-dependent installations is indicated.
Designing and Developing Ford Engines for Medium and Heavy Tanks
Authors: Ponta Peter H.
Published: December 2022

As the Ford Motor Company’s contribution to the present symposium on development of power plants for tanks, the author outlines the design and construction details of the 60-deg V-type eight-cylinder four-cycle gasoline tank engine of which 25,000 units were built for the Ordnance Department during the war. Solution of problems which developed during the early days of this engine are discussed. Finally, as track-laying combat machines such as gun carriers, became heavier, the demand for units of greater power brought about the design of the 60-deg twelve-cylinder engine, which the author mentions briefly.
Fracture of Some Aluminum Alloys Under Combined Stress
Authors: Thomsen E. G. , Cunningham D. M. , Dorn J. E.
Published: December 2022

An analytical determination of the forming limits of metals requires knowledge of plastic flow, buckling characteristics, local plastic behavior, and fracture laws of metals under combined stresses. Although the plastic flow of work-hardenable metals is now a fairly well-developed subject, our information on the remaining topics is incomplete; there is a great need for additional data on the fracture of metals under combined stresses. This need was recognized by the Office of Production Research and Development, which sponsored the following investigation as part of its “Study of the Forming Properties of Aluminum Alloy Sheet.” The data reported herein were selected exclusively from Part 19, OPRD. Report No. W-225, July 27, 1945, which has been released by the OPRD. In order to study the fracture of metals under combined stresses thin-walled tubular specimens of aluminum alloys 24S-T, 24S-T80, and 24S-T81 were subjected to axial loads and internal pressures. The ratios of load to pressure were adjusted to give stress ratios covering the tension-tension and tension-compression fields of biaxial stress. Predictions based upon the “critical normal stress law” and the “critical hydrostatic tension stress law” were in serious disagreement with the experimental facts, while predictions based upon the “critical shear stress law” were in approximate agreement.