bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimal Design for Energy Harvesting Vibration Absorbers
Authors: Wang Jiqiang
Published: December 2020

Energy harvesting vibration absorbers (EHVAs) represent a novel type of vibration absorbers where the dissipated energy is harnessed in the absorber system. Conventional optimization-based methods can be utilized for optimal design of EHVAs, but this usually involves in iterative design procedures, particularly for approaching performance limits. In this note, a visualization technique is proposed. The problem of existence and uniqueness solutions is addressed; the intimate relationship between energy harvesting and vibration suppression performances is disclosed; and the fundamental issue of determining performance limit with this visualized method is solved. These features form solid contributions of the current proposal over those optimization-based design methods. The corresponding design procedures are illustrated and the claims are further validated through real-time simulations to the optimal design of EHVAs.
Reducing Diffusion-Induced Stress of Bilayer Electrode System by Introducing Pre-Strain in Lithium-Ion Battery
Authors: Hao Wenqian , Xie Jiamiao
Published: December 2020

Lithium-ion battery (LIB), as energy storage devices, is widely used in portable electronic devices and have promising applications in electric vehicles. The volume change and large stress can lead to electrode pulverization and the resultant loss of electrical contact from the current collector, which is considered to be one of the main reasons for the capacity degradation of LIB. To reduce diffusion-induced stress of the electrode system during lithium-ion diffusion, a chemo-mechanical coupled theoretical model of bilayer electrode system of electrode layer bonded to the current collector is established. The theoretical results show that diffusion-induced stresses at the electrode–collector interface and maximum tensile stress at the top surface of the electrode layer are alleviated greatly by introducing pre-strain. The effects of pre-strain and lithium-ion concentration on chemo-mechanical coupled behavior of the bilayer electrode system are discussed. In particular, the lithium-ion concentration difference strongly depends on the diffusion thickness and time. The curvature when considering plastic deformation is smaller than that when not considering the plastic deformation. In addition, the effects of plastic deformation of the current collector and diffusion time on biaxial stress distribution are also discussed. The biaxial stress decreases with the increase of pre-strain and decrease of dimensionless time during galvanostatic charging. The biaxial stress when considering plastic deformation is smaller than that when not considering the plastic deformation. The results obtained from this investigation will provide a reference to reduce the diffusion-induced stress and improve the ion diffusion performance of LIB.
The Anisotropic Homogenized Model for Pouch Type Lithium-Ion Battery Under Various Abuse Loadings
Authors: Wang Huacui , Duan Xudong , Liu Binghe
Published: December 2020

Pouch type lithium-ion battery (LIB) has now been widely used in electric vehicles, smartphones, and computers. Mechanical abuse is one of the main reasons to cause the safety issues for lithium-ion battery. The highly accurate and efficient computational model is helpful for the safety design, application, and analysis of LIB. The previous homogenized mechanical models of the pouch LIB use different material parameters for various loading conditions. Herein, we establish an anisotropic homogenized method to predict the mechanical behavior in in-plane and out-of-plane directions simultaneously. Engineering constants and Hill's 48 criteria are used for the anisotropic properties, and bilinear plastic model is used as the hardening curve under large deformation. On the basis of this method, we established two homogenized models, i.e., one-layer model and multilayer model. Experiments in various loading conditions including three-point bending (length direction and width direction), out-of-plane compression, and in-plane compression (length direction and width direction) are conducted for parameters calibration. The calibration methods are then discussed and confirmed through these experiments. The computational models show good correlation with experiments in both in-plane and out-of-plane directions. The difference is that the global buckling behavior can be predicted by both of the two models, while the local buckling can be predicted only by the multilayer model. The results may shield light on the safety design, application, and analysis for pouch LIB.
Approximations for Steady Unidirectional Slip Flows in Elliptic Microchannels
Authors: Keady Grant
Published: December 2020

Consider steady flows in a channel whose cross section Ω is an ellipse, flows with the Navier slip boundary condition. Denote the volume flow rate by Q. We apply to elliptic cross section a recent simple approximation, a rigorous lower bound R on Q, requiring, along with the channel's area and perimeter, the calculation of just the torsional rigidity and two other domain functionals. This avoids the need for solving the partial differential equation repeatedly for differing values of the slip parameter.
Effects of Onshore and Offshore Environmental Parameters on the Leading Edge Erosion of Wind Turbine Blades: A Comparative Study
Authors: Shankar Verma Amrit , Jiang Zhiyu , Ren Zhengru , Hu Weifei , Teuwen Julie J. E.
Published: December 2020

The presence of rain-induced leading edge erosion of wind turbine blades (WTBs) necessitates the development of erosion models. One of the essential parameters for erosion modeling is the relative impact velocity between rain droplets and the rotating blade. Based on this parameter, the erosion damage rate of a WTB is calculated to estimate the expected leading edge lifetime. The environmental conditions that govern this parameter have site-specific variations, and thus, rain and wind loading on a turbine differ for onshore and offshore locations. In addition, there are wave loads present in the offshore environment. The present paper tries to provide guidelines for erosion modeling and investigates whether there are differences in erosion of blades due to (1) varying rainfall conditions modeled using different droplet size distributions for onshore and offshore locations in combination with (2) winds of varying turbulence intensities and (3) wave-induced loads. Aero-hydro-servo-elastic simulations are carried out for an onshore wind turbine (WT) and a monopile-supported offshore WT. Furthermore, erosion variables such as the relative impact velocities and the associated erosion damage rate of a blade are analyzed for various blade azimuth angles. The study shows that the rainfall intensity and turbulence intensity minorly influence the impact velocity and pressure but have a substantial effect on the overall erosion damage rate. Additionally, a significantly higher erosion damage rate is found for blades exposed to offshore rainfall conditions than for blades under onshore rainfall conditions. Furthermore, no substantial influence on erosion is found because of wave-induced loads.
Modal Analysis of Wake Behind Stationary and Vibrating Cylinders
Authors: Janocha Marek Jan , Yin Guang , Ong Muk Chen
Published: December 2020

The dynamic mode decomposition (DMD) and proper orthogonal decomposition (POD) are used to analyze the coherent structures of turbulent flow around vibrating isolated and piggyback cylinders configurations subjected to a uniform flow at a laminar Reynolds number (Re = 200) and a upper transition Reynolds number (Re = 3.6 × 106). Numerical simulations using two-dimensional unsteady Reynolds-averaged Navier–Stokes (URANS) approach with the k − ω shear stress transport turbulence model are used to obtain the flow fields snapshots for the analysis. The wake flows behind the cylinders are decomposed into energy optimal modes (POD modes) and dynamical relevant modes (DMD modes). A reduced-order model (ROM) for the flow is built based on the modal analysis. A comparison of POD and DMD is performed to characterize their special features. The present study provides new insights into the flow physics of fluid–structure interaction problem of two coupled cylinders. The characteristic vortex shedding frequencies and their harmonics are identified by DMD modes in all the investigated configurations. It is observed that for single cylinder configurations, the most energetic and the most dynamically important mode is associated with the fundamental shedding frequency. For the stationary piggyback configuration, the gap flow between the cylinders appears to be a dominant flow feature as evidenced by the leading DMD modes. The cylinder vibration increases significantly number of modes necessary to obtain a ROM at the given level of accuracy compared to respective stationary configurations.
Numerical Simulations of Turbulent Flow Through an Orifice Plate in a Pipe
Authors: Yin Guang , Nitter Bjørnar , Ong Muk Chen
Published: December 2020

Orifice flowmeters are widely used in industries to measure the flowrate in pipelines. The flowrate inside the pipe can be calculated using the relationship between the flow velocity and the pressure drop across the orifice plate. In the present study, numerical simulations have been carried out using three-dimensional Reynolds-averaged Navier–Stokes (RANS) equations combined with the k–ω shear-stress transport (SST) turbulence model to thoroughly investigate the turbulent flow through a circular square-edged orifice with various orifice plate thicknesses and orifice diameters inside a pipe at different Reynolds numbers ranging from 2500 to 40,000. The orifice thickness to pipe diameter ratio (t) varies between 0.125 and 2, and the orifice diameter to pipe diameter (β) varies between 0.25 and 0.75. The resulting centerline profiles of the streamwise velocity and pressure of the present study are compared with the previous published numerical results and experimental data as the validation study. The effects of Reynolds numbers and orifice geometries on the pressure, the flow velocity, and vorticity distribution in the orifice are discussed in detail. It is found that for the fixed β, the discharge coefficient increases with the increasing t, and the vortical structure inside the orifice is separated into two regions located at the two edges of the orifice. For the fixed t, the size of the large recirculation motions behind the plate increases, and the vorticity around the plate becomes stronger with the decreasing β.
Investigation of Different Groove Profile Effects on Torque Transmission in Shear Mode Magnetorheological Clutch: Numerical Simulation and Experimental Study
Authors: Thakur Manish Kumar , Sarkar Chiranjit
Published: December 2020

In this research paper, an attempt has been made to investigate the torque transmission characteristics in a radial magnetorheological (MR) clutch disc with different groove profiles. To estimate the transmitted torque, a numerical procedure is initiated by the implementation of the Bingham constitutive model into a magnetic field analysis followed by computational fluid dynamic (CFD) analysis. CFD results are presented for the analysis of transmitted torque between a plane driving disc and three different driven discs, i.e., plane, radial groove, and circular groove disc, under the conditions of different working radii, magnetic fields, and rotational speeds. The MR fluid (MRF) domain is modeled using a technique which can be applied for any wall texture of driving and driven disc. To verify the numerical findings, an MR clutch with three different discs and a MR transmission test bed have been built, and the influence of groove profile on the transmission torque of MRFs has been investigated on the test bed. The results are presented to obtain the relationships among torque performance, disc radius, rotational speed, and magnetic field. Numerical results show good agreement of torque transmission for different groove profiles with experiments. Finally, temperature distribution patterns in different three MR clutches and an optimization of the radial groove profile have been analyzed numerically.
Wear Analysis of Angular Contact Ball Bearing in Multiple-Bearing Spindle System Subjected to Uncertain Initial Angular Misalignment
Authors: Yang Zhongchi , Zhang Yu , Zhang Ke , Li Songhua
Published: December 2020

The effects of the uncertainty of angular misalignment on the wear of angular contact ball bearings in the spindle system are investigated. The wear model of bearing raceways is derived based on the Archard model. The angular misalignment caused by mounting error is assumed to comply with normal distribution, Monte Carlo method is used to extract the angular misalignment sample. Based on the spindle system model, the spinning speed, pitch angle, and contact force of ball elements in each angular contact ball bearing are calculated. The wear depth of bearing raceways is analyzed. The results show that the uncertainty of the initial angular misalignment leads to significant dispersion of wear depth of ball bearings, but the dispersion degree is related to spindle speed, angular misalignment cases, and bearing mounting position. Increasing the spindle speed increases the wear depth but decreases the wear depth dispersion.
Fluid–Structure Interaction Modeling of Elastohydrodynamically Lubricated Line Contacts
Authors: Singh Kushagra , Sadeghi Farshid , Russell Thomas , Lorenz Steven J. , Peterson Wyatt , Villarreal Jaret , Jinmon Takumi
Published: December 2020

This paper presents a partitioned fluid–structure interaction (FSI) solver to model elastohydrodynamic lubrication (EHL) of line contacts. The FSI model was constructed using the multiphysics simulation software ansys, wherein an iterative implicit coupling scheme is implemented to facilitate the interaction between fluid and solid components. The model uses a finite volume method (FVM) based computational fluid dynamics (CFD) solver to determine the lubricant flow behavior using the Navier–Stokes equations. Additionally, the finite element method (FEM) is utilized to model the structural response of the solid. Fluid cavitation, compressibility, non-Newtonian lubricant rheology, load balance algorithm, and dynamic meshing were incorporated in the FSI model. The pressure and film thickness results obtained from the model are presented for a wide range of loads, speeds, slide to roll ratios (SRR), surface dent, material properties (elastic plastic), etc. The model presents a detailed understanding of EHL contacts by removing any assumptions relative to the Reynolds equation. It provides the (i) two-dimensional variation of pressure, viscosity, etc., in the fluid and (ii) stress, elastic/plastic strain in the solid, simultaneously. The FSI model is robust, easy to implement, and computationally efficient. It provides an effective approach to solve sophisticated EHL problems. The FSI model was used to investigate the effects of surface dents, plasticity and material inclusions under heavily loaded lubricated line contacts as can be found in gears and rolling element bearings. The results from the model exhibit excellent corroboration with published results based on the Reynolds equation solvers.
GTAW Welded Inconel 625 Alloy Fuel Cladding for the Canadian SCWR: Microstructure and Mechanical Property Characterization
Authors: German Cota-Sanchez , Lin Xiao
Published: December 2020

Inconel 625 is considered one of the candidate materials for reactor fuel cladding in the Canadian supercritical water reactor (SCWR) design. Gas tungsten arc welding (GTAW) is being evaluated as a joining technique for SCWR fuel cladding since this method is widely used to join components in the power and nuclear industry. During the GTAW process, the welding thermal cycle produces different types of microstructures in both the heat-affected zone (HAZ) and fusion zone (FZ) that affect the material's mechanical properties. A series of welding experiments at various weld conditions were performed using an automatic GTAW orbital process on Inconel 625 alloy tubing. Simple analytical heat conduction and grain growth models were developed to predict weld temperature profiles and metallurgical transformations. Weld characterization included mechanical tests, optical microscopy, scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS) elemental analysis, and microhardness measurements. Weld microstructural characterization revealed that a characteristic dendritic structure was formed in the FZ, while the HAZ exhibited larger equiaxed grains than those found in the base material (BM). SEM-EDS analysis showed no distinct alloying element segregation in both the HAZ and FZ. Welds produced with heat inputs of about 3.00 J/mm3 presented similar mechanical properties as those observed in the BM. In these welds, grain growth was homogenously minimized in the FZ. It is concluded that the effective welding heat input control can optimize the weld microstructure and the weld mechanical properties in Inconel 625 tubing used as Canadian SCWR reactor fuel cladding.
The role of advanced multimodality imaging in chronic mitral regurgitation
Authors: Badau Riebel Catalina Ileana , Agoston-Coldea Lucia
Published: December 2020

Mitral regurgitation (MR), the second most common valvular heart disease, still constitutes a major diagnostic and thera-peutic challenge, due to its complex nature and to its consequences on cardiac remodelling. Life quality and expectancy are determined by the irreversibility of the left ventricular systolic dysfunction, which, despite current guidelines, remains a major drawback. In order to accurately establish “the point of no return” for left ventricular systolic function, the embedment of clinical, biological and imaging data is a requirement. The purpose of this review is to provide an overview of the current multimodal imaging techniques that are useful in correctly assessing patients with MR. Cardiac magnetic resonance strain imaging techniques and 3D echocardiography, in addition to current echocardiographic criteria may help identify the patients who will benefit from early surgery. The technical development of new transcatheter techniques in mitral valve repair could lead to the extension of current guidelines.
Spatially coherent regional changes in seasonal extreme streamflow events in the United States and Canada since 1950
Authors: Dethier Evan N. , Sartain Shannon L. , Renshaw Carl E. , Magilligan Francis J.
Published: December 2020

Extreme river discharge events (both high-flow and low-flow) are increasing in many regions in the United States and Canada.
Designing high-performance hypergolic propellants based on materials genome
Authors: Yuan Wen-Li , Zhang Lei , Tao Guo-Hong , Wang Shuang-Long , Wang You , Zhu Qiu-Hong , Zhang Guo-Hao , Zhang Zhang , Xue Ying , Qin Song , He Ling , Shreeve Jean’ne M.
Published: December 2020

Propellant materials genome offers a new approach to the design of high-performance hypergolic propellants.
Seasonality of diet costs reveals food system performance in East Africa
Authors: Bai Yan , Naumova Elena N. , Masters William A.
Published: December 2020

Synchronized food retail prices raise seasonal peaks in the cost of nutritious diets, revealing new ways to improve food systems.
Growth of pancreatic cancers with hemizygous chromosomal 17p loss of
MYBBP1A
can be preferentially targeted by PARP inhibitors
Authors: Hsieh Antony , Pitarresi Jason R. , Lerner Jonathan , Donahue Greg , Hsiehchen David , Rustgi Anil K. , Zaret Kenneth
Published: December 2020

Growth of pancreatic cancers with hemizygous chromosomal 17p loss of
MYBBP1A
can be preferentially targeted by PARP inhibitors.
Using migrating cells as probes to illuminate features in live embryonic tissues
Authors: Gross-Thebing Sargon , Truszkowski Lukasz , Tenbrinck Daniel , Sánchez-Iranzo Héctor , Camelo Carolina , Westerich Kim J. , Singh Amrita , Maier Paul , Prengel Jonas , Lange Pia , Hüwel Jan , Gaede Fjedor , Sasse Ramona , Vos Bart E. , Betz Timo , Matis Maja , Prevedel Robert , Luschnig Stefan , Diz-Muñoz Alba , Burger Martin , Raz Erez
Published: December 2020

Migrating cells can serve as probes for determining tissue properties in live embryos.
Giant nonreciprocity of surface acoustic waves enabled by the magnetoelastic interaction
Authors: Shah Piyush J. , Bas Derek A. , Lisenkov Ivan , Matyushov Alexei , Sun Nian X. , Page Michael R.
Published: December 2020

Giant nonreciprocity in a SAW-based microwave isolator device is reported offering substantial size and performance advantages.
Deep imaging in the brainstem reveals functional heterogeneity in V2a neurons controlling locomotion
Authors: Schwenkgrub Joanna , Harrell Evan R. , Bathellier Brice , Bouvier Julien
Published: December 2020

Calcium imaging of genetically defined neurons in the ventral brainstem during locomotion reveals unexpected functional diversity.
Synthetic high-density lipoproteins loaded with an antiplatelet drug for efficient inhibition of thrombosis in mice
Authors: He Hongliang , Adili Reheman , Liu Lisha , Hong Kristen , Holinstat Michael , Schwendeman Anna
Published: December 2020

sHDL is a promising antithrombotic agent delivery system due to its antithrombotic effect itself and improved drug delivery.
Mechanics-driven mechanobiological mechanisms of arterial tortuosity
Authors: Weiss Dar , Cavinato Cristina , Gray Authia , Ramachandra Abhay B. , Avril Stephane , Humphrey Jay D. , Latorre Marcos
Published: December 2020

Local microstructural defects and insidious positive feedback lead to tortuous arteries that disrupt blood flow.
Cooperative nature of viral replication
Authors: Andreu-Moreno Iván , Bou Juan-Vicente , Sanjuán Rafael
Published: December 2020

Group transmission of viruses accelerates early replication and increases short-term viral fitness.
Enabling near-atomic–scale analysis of frozen water
Authors: El-Zoka A. A. , Kim S.-H. , Deville S. , Newman R. C. , Stephenson L. T. , Gault B.
Published: December 2020

We propose a protocol for near-atomic–scale analysis of frozen water and embedded nanostructures by cryo–atom probe tomography.
Reliable, low-cost, fully integrated hydration sensors for monitoring and diagnosis of inflammatory skin diseases in any environment
Authors: Madhvapathy Surabhi R. , Wang Heling , Kong Jessy , Zhang Michael , Lee Jong Yoon , Park Jun Bin , Jang Hokyung , Xie Zhaoqian , Cao Jingyue , Avila Raudel , Wei Chen , D’Angelo Vincent , Zhu Jason , Chung Ha Uk , Coughlin Sarah , Patel Manish , Winograd Joshua , Lim Jaeman , Banks Anthony , Xu Shuai , Huang Yonggang , Rogers John A.
Published: December 2020

Smartphone-compatible, wireless, battery-free hydration sensors can monitor skin diseases in any environment.
Standalone or combinatorial phenylbutyrate therapy shows excellent antiviral activity and mimics CREB3 silencing
Authors: Yadavalli Tejabhiram , Suryawanshi Rahul , Koganti Raghuram , Hopkins James , Ames Joshua , Koujah Lulia , Iqbal Aqsa , Madavaraju Krishnaraju , Agelidis Alex , Shukla Deepak
Published: December 2020

PBA, a urea cycle disorder drug, alleviates ER stress, inhibits HSV infection, and synergizes with existing antivirals.
Airflows inside passenger cars and implications for airborne disease transmission
Authors: Mathai Varghese , Das Asimanshu , Bailey Jeffrey A. , Breuer Kenneth
Published: December 2020

We assess the impact of airflow on airborne coronavirus transmission risk to occupants in passenger cars.
Lighting a fire on the reef
Authors: Zhang Zhibin , Lieberman Judy
Published: December 2020

In response to infection in corals, activated caspase-3 cleaves gasdermin E to induce pyroptosis (see the related Research Article by

Jiang
et al
.

).
Staphylococci in Competition
Authors: Peterson A. C. , Black J. J. , Gunderson M. F.
Published: December 2020

In chicken pot pies, it was not possible to promote the growth of appreciable numbers of staphylococci under any condition of defrost. The pies spoiled under the same conditions, however. In macaroni and cheese dinners, tremendous numbers of saprophytic bacteria developed, but only after extended incubation at room temperature in which even spoilage was carried to an extreme. Under these conditions, staphylococci also multiplied vigorously. At the extreme temperature of 37 C, rank spoilage of such an advanced state as to render the product completely inedible was reached in less than 24 hr. Staphylococci grew very well under these extreme conditions.
Staphylococci in Competition
Authors: Peterson A. C. , Black J. J. , Gunderson M. F.
Published: December 2020

In studies carried on in bacteriological media with selected cultures, definite repressive effects were noted on the growth of the
Staphylococcus
population by a mixture of saprophytic, psychrophilic bacterial species. This repressive effect became more pronounced as the relative proportion of the bacterial population which was staphylococcal became smaller. A varied saprophytic bacterial flora of some numbers apparently would offer definite protection to foods through repression of staphylococcal growth and by rendering the food inedible before the rise of appreciable numbers of staphylococci. It would appear that at the optimal temperature for staphylococcal growth, staphylococci could multiply rapidly in the mixed population due to the comparative shortness of the generation time of this species and because of the lengthened lag phase of the saprophytic bacterial species at this elevated temperature, especially when only cultures having psychrophilic characteristics were present. This temperature is substantially above that encountered in practical experience. With the passage of time, the staphylococcal population was completely overgrown by the saprohytes present. This effect might be eliminated in the presence of psychrophilic and mesophilic, saprophytic species. The repressive effect of competition by saprophytic, psychrophilic organisms is extremely effective up to room temperature on the staphylococcal population. Even when significant staphylococcal populations were achieved in the artificial media, such tremendous numbers of saprophytes were obtained either earlier or at the same time so that a frozen food containing this population would be organoleptically unacceptable due to the degradative action of enzymes from the saprophytic psychrophile population.
Production of Fumaric Acid in 20-Liter Fermentors
Authors: Rhodes R. A. , Lagoda A. A. , Misenheimer T. J. , Smith M. L. , Anderson R. F. , Jackson R. W.
Published: December 2020

The conditions necessary for the production of fumaric acid in 20-liter fermentors by fermentation of glucose with
Rhizopus arrhizus
strain NRRL 2582 were determined. Continuous neutralization of fumaric acid was necessary for optimal yields. Yields of the calcium salt were in excess of 65 g of fumaric acid from 100 g of sugar consumed during fermentation of sugar concentrations of 10 to 16%. Conditions established for calcium fumarate production include a simple mineral salts medium, 0.5 v:v:min aeration rate, 300 rev/min agitation rate in a baffled tank, 33 C incubation temperature, CaCO
3
to neutralize the acid formed, and a 4 to 5% (v/v) vegetative inoculum. A suitable procedure and medium for the preparation of a vigorous vegetative inoculum were established. The tendency for calcium fumarate fermentations to foam excessively was controlled with a proper antifoam agent added prior to sterilization of the medium and again at daily intervals during fermentation. The production of soluble sodium or potassium fumarates was inhibited when the concentration of fumarates reached 3.5 to 4.0%. No means of overcoming this inhibition was found. Starches and certain other grain-derived carbohydrates were fermented to form calcium fumarate in flask experiments with approximately the same efficiency as was glucose.
Materials of Construction in Algal Culture
Authors: Dyer Denzel L. , Richardson D. E.
Published: December 2020

A number of plastics and metals were tested for their compatibility with the algae
Synechococcus lividus
and
Chlorella pyrenoidosa
strain TX71105 in a nitrate medium at pH 7.5. Plastics in general were not inhibitory. Of the metals tested, copper and some of its alloys inhibited growth. Other copper alloys did not. Seven aluminum alloys were entirely compatible.
Purification and Characterization of a Growth Stimulant for
Bacillus
Species
Authors: Traxler R. W. , Lankford C. E. , Shive William
Published: December 2020

A procedure is described whereby the growth stimulatory material from an autoclaved solution of glucose and phosphate can routinely be purified 689-fold. Chemical characterization of this purified material indicates the presence of a hydroxyl group and possibly a carboxyl group on the active factor(s) which are associated with activity. Evidence is presented that there are two active factors or two forms of the same factor present in the concentrate.
A Monitor for Airborne Bacteria
Authors: Andersen A. A. , Andersen M. R.
Published: December 2020

A unique agar drum sampler is described which indicates, continuously, the number of viable, bacterial particles per unit volume of air at the time and point of sampling. By selection of the timer and the sampling rate the sampler is suitable for quite a wide range of concentration and time. An impaction line of 484 in. greatly increases the capacity of this device over slit samplers and other instruments designed to give time-concentration data for viable airborne particles. This sampler should prove useful for: (i) monitoring airborne bacteria in hospitals, public places, and food and industrial plants; (ii) decay rate studies of bacterial aerosols; (iii) evaluation of aerial germicides; (iv) determination of effectiveness of air conditioning systems in removing airborne bacteria; and (v) many other studies in aerobiology.
Further Studies on Staphylococci in Meats,
Authors: Jay James M.
Published: December 2020

From 34 retail grocery stores and meat markets, 209 samples of nonfrozen meats were obtained and analyzed for coagulase-positive
Staphylococcus aureus
, employing six selective media. Sixty-seven (38.7%) of 173 samples obtained from 27 stores yielded
S. aureus
. No coagulase-positive
S. aureus
was isolated from 36 samples obtained from 7 of the stores. The 67 meats yielded 272 isolates from 10 different kinds of meats. There were 162 physiological strains represented when classified by store and 36 strains classified without regard to store of origin. The larger stores yielded fewer meats with staphylococci than the smaller stores. The meats from which
S. aureus
was recovered in the order of frequency of percentage recovery are as follows: chicken, pork liver, fish, spiced ham, round beef steak, hamburger, beef liver, pork chops, veal steak, and lamb chops. The following seven meats did not yield staphylococci: bologna, shucked oysters, olive and pickle loaf, salami, wieners, and chopped ham. Eighty-eight per cent of the isolates produced pigment, 85% were gelatinase positive, only 1 strain failed to form a precipitate on egg yolk agar, 92% formed deoxyribonuclease, 87% produced bound coagulase, 91% produced the α-hemolysin, 70% the δ-, 22% the β-, and 6% were nil in this regard. The isolates are compared with hospital and other food strains, and their possible source in the meats is discussed.
Studies on Induction and Repression in Activated Sludge Systems
Authors: Gaudy Anthony F.
Published: December 2020

Both repression and induction of substrate utilization have been the subject of many basic research investigations employing pure cultures. In this investigation these effects were studied using heterogeneous microbial populations prevalent in such biological treatment processes as activated sludge systems.

Diauxic substrate removal by activated sludge was observed in a multicomponent medium consisting of glucose and sorbitol. The sludge was acclimated solely to sorbitol; however, the presence of glucose blocked sorbitol removal until glucose was completely utilized. Both diphasic and triphasic oxygen utilization was shown for activated sludges metabolizing multicomponent synthetic wastes consisting of glucose, melibiose, and lactose. It appears from these studies that melibiose utilization was suppressed by the presence of glucose and, although melibiose induced acclimation to lactose, the presence of melibose suppressed lactose utilization. Studies were also conducted using glycogen and starch systems in which it was found that acclimation to either compound conferred immediate acclimation to the other. It was also found that loss of acclimation to lactose was a passive phenomenon and its kinetics could be predicted on the basis of simple diluting out of the enzyme(s) responsible for such acclimation.
Microflora of Barley Kernels
Authors: Follstad M. N. , Christensen C. M.
Published: December 2020

Numbers and kinds of microflora were determined in 160 samples of barley grown in different regions of the United States; microflora were more abundant in the grains grown in the central states than in those grown in the western states. During steeping and germination in micromalting equipment, the number of colonies of filamentous fungi increased from two to five times, colonies of yeasts from five to ten times, and bacteria from 50 to more than 100 times the numbers present in the grain before malting. Kiln drying according to a commercial schedule reduced the number of all types of microflora below the number present before kilning, but all were present in larger numbers in the kilned malt than in the original grain. In barley stored at room temperature and at a moisture content of 15 to 18%, members of the
Aspergillus glaucus
group increased with increasing time and increasing moisture content, and germination percentage of the seeds decreased. Stored free of storage fungi at room temperature, barley with a moisture content just over 15% retained a high germination percentage for 5 months, but at a moisture content of 16% the germination decreased to zero.
Psychrophilic and Mesophilic Fungi in Fruit-Filled Pastries
Authors: Kuehn Harold H. , Gunderson Millard F.
Published: December 2020

Surveys of the mold flora of frozen blueberry and cherry pastries were undertaken. Molds were enumerated by preparing pour plates of the blended product and incubating the plates at 0, 5, 10, and 20 C. In this manner, the total fungal content of the product could be ascertained from the 10 and 20 C plates, and the psychrophilic fungal population was represented by those fungi which grew at 0 and 5 C. The pastry portion, or crust, of the blueberry material was sampled separately from the filling portion. Certain differences in fungal flora were apparent.
Aureobasidium pullulans
was the dominant fungus in crust at all temperatures of isolation. However,
Penicillium thomii
proved to be the most common mesophilic fungus in the filling portion, and
A. pullulans
was the most common psychrophile in the filling. Aspergilli were quite common in the crust, but, in general, were absent from the fruit filling. Cherry pastries had a much smaller total fungal flora than did the blueberry product. However,
A. pullulans
again was the most prevalent fungus in cherry pastries at all temperatures of isolation. Certain differences in fungal flora were apparent in the two fruit products.
Phoma
spp. were almost completely absent in blueberries, but represented the second most common fungus in cherry pastries. Blueberry filling had 440 psychrophilic fungi per gram of sample (at 0 C), blueberry crust had 65 per gram, and cherry pastries had 77 per gram.
Action of Deflocculating Agents on
Saccharomyces cerevisiae
Class III Brewer's Yeast
Authors: Lycette R. M. , Hedrick L. R.
Published: December 2020

Earlier work with a fluorescent aid indicated that flocculent brewer's yeast may have more surface lipids than nonflocculent types. Organic solvents were checked against flocculent Gilliland yeasts. It was found that those reagents which affect “free” lipids had no dispersive action, and those which remove “bound” fats had a powerful dispersive action against such yeasts. There was no indication that such an action could be correlated with other physical properties of the solvents. The uranyl ion is known for its ability to complex with phospholipids, and it was found to have a powerful dispersive action on Gilliland yeasts. Its effect was compared with that of glucose in its dispersion of yeast flocs, and possible cell “sites” were suggested. This, along with other work, suggests the possibility that lipids are directly or indirectly involved in yeast flocculation.
Activation of Dry Starter Cultures in Milk
Authors: Speck M. L. , Koburger J. A.
Published: December 2020

The revitalization of mixed strain dried starter cultures at 22 and 32 C in sterile skim milk was materially accelerated when the substrate was fortified with 0.2% pancreas-extract solids. At 22 C, all cultures grew up satisfactorily in 18 hr, and in unfortified milk none of the cultures reached comparable growth in this period. When the cultures were grown at 32 C, the dried cultures developed adequately in 7.5 hr, but required 9 to 10 hr in plain milk. Culture growth was enhanced in milk containing pancreas extract to the extent that the amount of dried culture required to produce adequate acidity in normal incubation times could be markedly reduced. At 32 C, certain cultures could be reduced to 12.5% of recommended amounts, and at 22 C certain ones could be reduced by 50%. Revitalization of the dried cultures in milk containing pancreas extract did not affect the growth of subcultures in plain milk. Also, when dried cultures initiated growth in fortified milk at 32 C their subsequent growth at 22 C in milk alone was not affected. The faster rate of culture growth in milk containing pancreas extract should permit, with more certainty, the establishment of active mother and bulk starters. Furthermore, economy of dried cultures, as well as of time, could be realized by the use of fortified milk.
Biosynthesis of Cephalosporin C
Authors: Ott J. L. , Godzeski C. W. , Pavey D. , Farran J. D. , Horton D. R.
Published: December 2020

A series of complex and synthetic media have been developed that are suitable for the production of cephalosporin C and cephalosporin N by a mutant strain of
Cephalosporium
(C.M.I. 49,137).
dl
-Methionine increased the yield of both antibiotics, with more effect on cephalosporin N.
l
-Cystine had a greater enhancing effect on formation of cephalosporin C than on formation of cephalosporin N in synthetic media; serine increased yields of cephalosporin C under certain conditions. Disaccharides or polysaccharides appeared to be the best source for carbohydrates. No evidence was found for precursor action such as is found in penicillin fermentations. The ability of resting cells to produce antibiotic was demonstrated.
Microbiological Transformation of Terpenes
Authors: Prema B. R. , Bhattacharyya P. K.
Published: December 2020

Several strains of fungi were tested for their ability to metabolize α-pinene in shake cultures. A strain of
Aspergillus niger
showing marked efficiency in this respect was selected for further studies. The optimal conditions for fermentation were established with respect to substrate concentration, time, and temperature. From the fermentation products three major metabolites of α-pinene were isolated: a ketone, C
10
H
14
O, identified as
d
-verbenone; an alcohol, C
10
H
16
O, identified as
d-cis
-verbenol; and a crystalline diol, C
10
H
18
O
2
, characterized as
d-trans
-sobrerol.
Effect of Bromide-Hypochlorite Bactericides on Microorganisms
Authors: Shere Lewis , Kelley Maurice J. , Richardson J. Harold
Published: December 2020

A new principle in compounding stable, granular bactericidal products led to unique combinations of a water-soluble inorganic bromide salt with a hypochlorite-type disinfectant of either inorganic or organic type. Microbiological results are shown for an inorganic bactericide composed of chlorinated trisodium phosphate containing 3.1% “available chlorine” and 2% potassium bromide, and for an organic bactericide formulated from sodium dichloroisocyanurate so as to contain 13.4% “available chlorine” and 8% potassium bromide. Comparison of these products with their nonbromide counterparts are reported for
Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Streptococcus lactis, Aerobacter aerogenes
, and
Proteus vulgaris
. Test methods employed were the Chambers test, the A.O.A.C. Germicidal and Detergent Sanitizer-Official test, and the Available Chlorine Germicidal Equivalent Concentration test. The minimal killing concentrations for the bromide-hypochlorite bactericides against this variety of organisms were reduced by a factor 2 to 24 times those required for similar hypochlorite-type disinfectants not containing the bromide.
Growth of
Streptococcus faecalis
var.
liquefaciens
on Plants
Authors: Mundt J. Orvin , Coggin J. H. , Johnson L. F.
Published: December 2020

The proliferation of
Streptococcus faecalis
var.
liquefaciens
on two varieties of beans, and on corn, rye, and cabbage was investigated. Comparisons were made with growth patterns on these same plants exhibited by
S. lactis
and
Lactobacillus plantarum
. The ability of each of the bacteria to multiply and to spread to new plant parts as they developed from seed was studied under several environmental conditions. Plants were grown aseptically in glass culture and in sterilized and non-sterilized soil in the greenhouse. Quantitative estimations of increase in bacterial numbers were made.
S. faecalis
established commensal growth on each of five plants, although selectivity was noted for some plant parts. The organism increased in numbers on the plants equally as well as did the control bacteria, both alone, and in competition with the control bacteria and the microflora of the soil.
Microbiological Contamination of Hospital Air
Authors: Greene V. W. , Vesley D. , Bond R. G. , Michaelsen G. S.
Published: December 2020

The levels of airborne contamination in various areas of two hospitals were determined during a 15-month sampling period, using Casella and Andersen volumetric samplers. Based on nearly 5,000 samples, the mean count per ft
3
ranged from 4.5 in obstetric-gynecology delivery rooms to 72.4 in waste-handling areas. The mean count for the entire hospital environment was on the order of 20 contaminants per ft
3
; 48% were associated with particles >5 μ diam, 30% with particles between 2 and 6 μ diam, and 22% with particles <2 μ diam. The airborne contamination was influenced by traffic, activity, ventilation considerations, and gross surface contamination, but not markedly by seasonal changes. When suitable control measures were implemented, the level of contamination could be diminished and kept low.
Microbiological Contamination of Hospital Air
Authors: Greene V. W. , Vesley D. , Bond R. G. , Michaelsen G. S.
Published: December 2020

Over 10,000 airborne microorganisms, isolated from various areas of two hospitals, were characterized according to colonial and microscopic morphology and certain physiological reactions, including penicillin resistance and hemolysis. On the basis of all isolates examined during a 15-month period, 42.6% were gram-positive cocci, 19.2% were gram-positive rods, 14.0% were gram-negative rods, 17.1% were molds, 2.2% were actinomycetes, 1.2% were yeasts, and the remainder were assorted diphtheroids and coccobacillary types. The distribution of types varied according to hospital area, locations within a given area, and level of gross airborne contamination, but did not vary significantly with season of the year. There appeared to be some relationship between contaminant particle size and type of organism associated with the particle. Distribution of penicillin-resistant types differed markedly in different hospital areas, with proportions ranging from 21.4% in surgery areas to 4.3% in incinerator rooms. Of all gram-positive cocci isolated, 34.9% were hemolytic, and 16.4% were penicillin-resistant.
Production of Mushroom Mycelium as a Protein and Fat Source in Submerged Culture in Medium of Vinasse
Authors: Falanghe H.
Published: December 2020

Of ten mushroom cultures investigated, only
Agaricus campestris, Boletus indecisus
, and
Tricholoma nudum
were capable of growing in submerged culture in medium of vinasse with added salts. Higher fermentative efficiencies were found under these conditions than in medium containing molasses or waste sulfite liquor.
A. campestris
showed a better capacity to produce protein but, since
B. indecisus
is capable of developing greater mycelium weight, its fermentative efficiencies are comparable. Both microorganisms could be grown in medium of vinasse with greatly varied amounts, producing higher mycelial weight in media with greater vinasse. The capacity of
B. indecisus
and
A. campestris
to utilize the noncarbohydrate fraction in total solids, instead of the total carbohydrates when they are in smaller amount, was observed in medium containing vinasse.
B. indecisus
and
A. campestris
were easily separated by filtration from the medium, although
T. nudum
was difficult to separate by this procedure. In experiments with
A. campestris
, the adaptative capacity of the organism to vinasse was demonstrated.
Ballistic Disruption of
Penicillium chrysogenum
Cells
Authors: Hamilton Pat B. , Knight S. G.
Published: December 2020

The use of glass beads in a high-speed mixing device to rupture organisms was applied to molds. The use of a mixer in which the propellor shaft enters from the top into a metal mixing chamber made it possible to immerse the whole device in a salt water and ice mixture so that the temperature of the glass-bead slurry could be kept below 5 C without difficulty. Mycelia, glass beads, and buffer in a 1:2:3 (w/w) ratio gave above 95% breakage in 15 min with
Penicillium chrysogenum
cells and in 4 min with
Rhizopus nigricans
. Some of the factors influencing breakage are discussed.
Distribution and Substrate Specificity of Benzylpenicillin Acylase
Authors: Huang H. T. , Seto T. A. , Shull G. M.
Published: December 2020

Benzylpenicillin acylase, which hydrolyzes benzylpenicillin to 6-aminopenicillanic acid, was found to be widely distributed among members of the
Schizomycetes
, particularly in gram-negative bacteria, and in the genus
Nocardia
. The hydrolysis of a series of biosynthetic and semisynthetic penicillins by freeze-dried cells of a strain of
Nocardia
and of
Proteus
was studied. Benzylpenicillin was the preferred substrate; all departures from the benzylpenicillin side-chain structure led to reduction of substrate activity (the greater the departure, the greater the reduction in activity). Penicillin amides and methyl esters were also hydrolyzed, as were suitable
N
-acyl derivatives of 7-aminocephalosporanic acid. Occurrence of an enzyme activity which hydrolyzes benzylpenicillinamide to benzylpenicillin was detected in certain strains of yeasts.
Bacteriology of Manganese Nodules
Authors: Ehrlich Henry L.
Published: December 2020

Bacteria, found in manganese nodules from the Atlantic Ocean, enhance the adsorption of Mn
++
from sea water by crushed manganese nodules in the presence of peptone. When bacterial outgrowth from crushed manganese nodules was experimentally delayed, peptone did not enhance Mn
++
adsorption by nodular substance, but hindered it in some cases. A mechanism to explain the role of bacteria in enhancing Mn
++
adsorption by manganese nodules is presented. Oyster shells were shown to adsorb Mn
++
in the absence of bacteria. Peptone did not enhance the rate of Mn
++
adsorption. Adsorbed Mn
++
was not visibly oxidized during experimental observation. These results suggest one way whereby nodule formation may be initiated in the oceans. Some bacteria in the nodules were found to release manganese from them in the presence of glucose and peptone. Bacteria may, therefore, play a role not only in nodule buildup but also in nodule breakdown.