Large Packing Research Articles

Thermal performance determination of binary Fe-Al alloys at elevated temperatures

The thermal expansion and thermal diffusion properties of Fe−Al alloys were measured using dilatometric and laser flash methods. At two allotropic transformation temperatures, the length change of the rapidly solidified pure Fe by injection casting deviates from that of the pure Fe by heating-cooling processing in a dilatometer. The ferro-/paramagnetic transition and second order transition do not influence the thermal expansion behaviors of Fe−Al alloys as temperature increases from 473 to 1373 K. The thermal expansion coefficients of Fe70Al30, Fe60Al40 and Fe55Al45 alloys are apparently larger than those of Fe25Al75 and Fe90Al10 alloys. Once temperature exceeds 877 K, the thermal expansion coefficients of Fe-Al alloys are enhanced with the increase of Al content, except for Fe25Al75 alloy owing to the large packing factor of FeAl3 crystal structure. In the temperature range from 309 to 877 K, the thermal diffusivity as a function of temperature decreases in the sequence of Fe90Al10, Fe55Al45, Fe60Al40, Fe70Al30 and Fe25Al75, and their values are lower than that of pure Fe at the same temperatures. As temperature increases, the thermal diffusivity values of Fe−Al alloys increase, except that of Fe90Al10 alloy decreases in the temperature range from 294 to 979 K and then increases once temperature further increases to 1078 K because of the ferro-/paramagnetic transition. Their thermal expansion coefficient and thermal diffusivity serve as linear or polynomial functions of temperature.

Partial Zone II Resuscitative Endovascular Balloon Occlusion of the Aorta in Management of Multiple Trauma with Combined Abdominal and Pelvic Injury

Introduction: Resuscitative endovascular balloon occlusion of the aorta has been used in various clinical settings to elevate blood pressure in the setting of shock, even if the evidence base is weak with no clear indications. Case presentation: We report a case of traumatic hemorrhagic shock in which this technique was used in an unusual manner, treating obvious arterial abdominal bleeding associated with suspected pelvic arterial bleeding, in a Trauma Center where hybrid angiographic-surgical suite is not available. A 35-year-old man was involved in a traffic accident within 2 trucks. He was transported to the Major Trauma Center of an Integrated Trauma System where emergent laparotomy confirmed massive hepatic rupture and a bleeding control was obtained by large abdominal packing. Trauma team decided to considerate Resuscitative Endovascular Balloon Occlusion of the Aorta, positioning a deflated balloon in zone III to eventually manage a pelvic arterial hemorrhage, while performing Bogota Bag. Suddenly a new abdominal arterial bleeding was noted through Bogota Bag. Because Pringle maneuver was considered too difficult in this case because of liver hilum injury, the balloon was moved cranially with the aim to reach zone I. Introducer sheath displacement occurred at this time, and the balloon was then only partially inflated in zone II, usually considered too dangerous, and immediately the target systolic blood pressure of 90 mmHg was obtained. Transfer the patient into interventional radiology suite was then feasible and embolization of active bleeding by right hepatic artery and superior mesenteric artery branch, missed during first laparotomy, were performed. Balloon was definitely deflated after 50 minutes. The patient was discharged by the hospital 113 days later, fully recovered with long lasting motor rehabilitation program. Discussion: Partial zone II Resuscitative Endovascular Balloon Occlusion of the Aorta in this particular case allowed overcoming procedural mistakes without major complications and with good clinical outcome. Conclusion: Judicious manage of REBOA inflation time and amount, together with multidisciplinary contemporary damage control strategy with clear and effective team leading, is the key to effectively resuscitate multiple trauma shocked patients.

Failure mechanisms of Ni-H2 and Li-Ion batteries under hypervelocity impacts

Lithium-Ion (Li-Ion) batteries have yielded significant performance advantages for many industries, including the aerospace industry, and have been selected to replace nickel hydrogen (Ni-H2) batteries for the International Space Station (ISS) to meet the energy storage demands. As the ISS uses its vast solar arrays to generate its power, the solar arrays meet their sunlit power demands and supply excess power to battery packs for power delivery on the sun obscured phase of the approximate 90 minute low Earth orbit. These large battery packs are located on the exterior of the ISS, and as such, the battery packs are exposed to external environment threats like naturally occurring micrometeoroids and artificial orbital debris (MMOD). While the risks from these solid particle environments has been known and addressed to an acceptable risk of failure through shield design, it is not possible to completely eliminate the risk of loss of these assets on orbit due to MMOD motivating a study into the failure consequences to the ISS. This paper documents the different failure modes for these two types of batteries under hypervelocity impact and the implications for spacecraft survivability when shielding is breached.

Cytological study of Сhloromonas typhlos (Chlamydomonadaceae, Chlorophyta) from North-Western Russia

The strain of biflagellated green monad, selected from the specimen gathered in the Novgorod Region was studied by light and electron microscopy. The species was identified on the base of coincidence of the majority of specific light and ultrastructural signs revealed in both the strain SAG 26.86 of Chloromonas typhlos (Gerloff) Matsuzaki et al. and in studied strain. On LM level the cells are ellipsoid, some asymmetric, 12–17 μm long, 8–13 μm wide, with an apical, hardly distinguished hemispherical papilla flattened on the top. Chloroplast parietal, cup-shaped, thickened on one side, with big lobes, irregular incisions and fissures on the surface. These and other features are characteristic of the type and the studied strain of C. typhlos, excluding stigma observed in the studied strain only. On the ultrastructural level, large thylakoid packs, similar with chloroplast thylakoids, were observed in pyrenoids of both strains of C. typhlos. The detected pyrenoid type was never discovered in chlamydomonads earlier. It is the first record of C. typhlos for the Novgorod Region and the whole Russia, and adds the list of «bloom-forming» species. The strain was deposited in the collection of microalgae strains in the Institute of Biology of Komi Scientific Centre under the name SYKOA Ch-063-17.

Direct measurements of the drag force over aligned arrays of cubes exposed to boundary-layer flows

Wind tunnel measurements of the total drag force for aligned arrays of cubes exposed to two different boundary-layer flows at three flow velocities are discussed. The drag force for eight different building packing densities λp (from 0.028 to 1) is measured with a standard load cell generating a novel dataset. Different λp are reproduced by increasing the number of buildings on the same lot area; this represents a real situation that an urban planner is faced with when a lot area of a given (fixed) size is allocated to the development of new built areas. It is assumed that the surrounding terrain is uniform and there is a transition from a given roughness (smooth) to a new roughness (rough). The approaching flow will adjust itself over the new surface within a distance that in general may be larger than the horizontal length covered by the array. We investigate the region where the flow adjustment occurs. The wide range of packing densities allowed us to analyse in detail the evolution of the drag force. The drag force increases with increasing packing densities until it reaches a maximum at an intermediate packing density (λp = 0.25 in our case) followed by a slight decrease at larger packing densities. The value of the drag force depends on the flow adjustment along the array which is evaluated by introducing the parameter “drag area” to retrieve information about the drag distribution at different λp. Results clearly suggest a change of the distribution of the drag force, which is found to be relatively uniform at low packing densities, while most of the force acts on first rows of the arrays at large packing densities. The drag area constitutes the basis for the formulation of a new adjustment length scale defined as the ratio between the volume of the air within the array and the drag area. The proposed adjustment length scale automatically takes into account the change in drag distribution along the array for a better parameterization of urban effects in dispersion models.

Differences in prices and price risk across alternative marketing arrangements used in the fed cattle industry

Information on prices and price risk differences across marketing arrangements aids fed cattle producers in making choices about marketing methods. As part of the congressionally mandated Livestock and Meat Marketing Study, we investigated fed cattle price and price risk differences across marketing arrangements. The analysis uses data representing cattle purchased by 29 large beef packing plants from October 2002 through March 2005. Results indicate that marketing agreements offered the best tradeoff between price level and price risk. Forward contracts had the lowest average yet highly volatile prices. Auction barn prices were higher than other methods but also the most volatile.

Evaluation of a Novel BEV Concept Based on Fixed and Swappable Li-Ion Battery Packs

In this paper, a novel battery electric vehicle (BEV) concept based on a small fixed and a big swappable Li-ion battery pack is proposed in order to achieve longer range, lower initial purchase priceand lower energy consumption at short ranges. For short ranges, the BEV is only powered by the relatively small-fixed battery pack, without the large swappable battery pack. In this way, the mass of the vehicle is reduced and, therefore, the energy consumed per unit distance is improved. For higher ranges, the BEV is powered by both battery packs. This concept allows the introduction of subscription-based ownership models to distribute the cost of the large battery pack over the vehicle lifetime. A methodology is proposed for the analysis and evaluation of the proposed concept in comparison with a direct owned nonswappable single-pack BEV, proving that significant improvements on city fuel economy (up to 14%) and economic benefits are achievable under several scenarios. These results encourage further study of battery swapping service plans and energy management strategies.

Synthesis of Active Cell Balancing Architectures for Battery Packs

Active balancing architectures effectively increase the efficiency of large battery packs by equalizing charge between cells. For this purpose, a balancing circuit and appropriate control scheme have to be designed to enable the charge transfer via energy storage elements such as inductors. Using a manual approach to design balancing architectures can be tedious and error-prone, resulting in potentially suboptimal solutions. As a remedy, this paper presents an automatic synthesis of balancing circuits and their corresponding control, optimizing the number of required metal-oxide-semiconductor field-effect transistors, and necessary control signals. The proposed synthesis combines a satisfiability solver to explore the search space with a graph-based verification that iteratively excludes infeasible solutions until the optimal architectures are obtained. The experimental results are carried out for three given template circuits and two signal templates. The synthesis results in architectures that are superior in terms of all design objectives in comparison to solutions from literature that result from a manual design approach.

Hybrid Diesel-Electric Drivetrain for Small Agricultural Field Machines

In this project, a series electric drivetrain sized for small agricultural machinery was developed and tested. Electric drives have noted benefits in simplicity, controllability, integration with other electronics such as those that provide autonomous action, and in efficiency over a wide operating range. Their biggest drawback for agricultural use is the limited capacity of electrical energy storage. A series hybrid drivetrain provides a method to overcome these capacity constraints through the use of chemical energy storage. The series hybrid drivetrain in this research was designed using well-established components. It consisted of a diesel-electric generator, a lead acid battery pack, a motor controller, and independent electric motors for each wheel with associated gearboxes to produce speeds and torques suitable for ground drive. Although these components are commercially available, they have not been integrated into a hybrid drivetrain before. The goal of this project was to test this drivetrain to determine its baseline performance and investigate the efficiencies of the various drivetrain components when operating under different conditions. The drivetrain efficiency was tested using a 2 x 2 x 2 factorial test in which the factors were average load level (30% or 40% of full load), load profile type (variable or constant), and size of the battery pack (170 or 340 A.h). The efficiencies of the three main components of the drivetrain were monitored in this testing: the diesel-electric generator, the battery system, and the ground drive. Of the tested factors, only load level had an effect on efficiency and then only on the overall efficiency and on the efficiency of the battery system. The other system components were not appreciably impacted by any of the factors. Large battery packs were not necessary to maintain efficiency even with variable loads, which indicates that future machines could consider more advanced (but more expensive) types of batteries, as less capacity would be required. Agricultural engineers interested in using electric motor drives because of their various benefits can use a series hybrid design to overcome their energy storage limitations and realize consistent efficiencies in a variety of operating conditions.

Modern Advances in Wireless Power Transfer Systems for Roadway Powered Electric Vehicles

Wireless power transfer system (WPTS)-based wireless electric vehicles, classified into roadway-powered electric vehicles (RPEVs) and stationary charging electric vehicles (SCEVs), are in the spotlight as future mainstream transportations. RPEVs are free from serious battery problems such as large, heavy, and expensive battery packs and long charging time because they get power directly from the road while moving. The power transfer capacity, efficiency, lateral tolerance, electromagnetic field, air-gap, size, weight, and cost of the WPTSs have been improved by virtues of innovative semiconductor switches, better coil designs, roadway construction techniques, and higher operating frequency. Recent advances in WPTSs for RPEVs are summarized in this review paper. The fifth- and sixth-generation online electric vehicles, which reduce infrastructure cost for commercialization, and the interoperability between RPEVs and SCEVs are addressed in detail in this paper. Major milestones of the developments of other RPEVs are also summarized. The rest of this paper deals with a few important technical issues such as coil structures, power supply schemes, and segmentation switching techniques of a lumped inductive power transfer system for RPEVs.

A comprehensive review of on-board State-of-Available-Power prediction techniques for lithium-ion batteries in electric vehicles

Abstract This study provides an overview of available techniques for on-board State-of-Available-Power (SoAP) prediction of lithium-ion batteries (LIBs) in electric vehicles. Different approaches dealing with the on-board estimation of battery State-of-Charge (SoC) or State-of-Health (SoH) have been extensively discussed in various researches in the past. However, the topic of SoAP prediction has not been explored comprehensively yet. The prediction of the maximum power that can be applied to the battery by discharging or charging it during acceleration, regenerative braking and gradient climbing is definitely one of the most challenging tasks of battery management systems. In large lithium-ion battery packs because of many factors, such as temperature distribution, cell-to-cell deviations regarding the actual battery impedance or capacity either in initial or aged state, the use of efficient and reliable methods for battery state estimation is required. The available battery power is limited by the safe operating area (SOA), where SOA is defined by battery temperature, current, voltage and SoC. Accurate SoAP prediction allows the energy management system to regulate the power flow of the vehicle more precisely and optimize battery performance and improve its lifetime accordingly. To this end, scientific and technical literature sources are studied and available approaches are reviewed.

Coupled electrochemical thermal modelling of a novel Li-ion battery pack thermal management system

Thermal management system is of critical importance for a Li-ion battery pack, as high performance and long battery pack life can be simultaneously achieved when operated within a narrow range of temperature around the room temperature. An efficient thermal management system is required to keep the battery temperature in this range, despite widely varying operating conditions. A novel liquid coolant based thermal management system, for 18,650 battery pack has been introduced herein. This system is designed to be compact and economical without compromising safety. A coupled three-dimensional (3D) electrochemical thermal model is constructed for the proposed Li-ion battery pack. The model is used to evaluate the effects of different operating conditions like coolant flow-rate and discharge current on the pack temperature. Contact resistance is found to have the strongest impact on the thermal performance of the pack. From the numerical solution, a simple and novel temperature correlation of predicting the temperatures of all the individual cells given the temperature measurement of one cell is devised and validated with experimental results. Such coefficients have great potential of reducing the sensor requirement and complexity in a large Li-ion battery pack, typical of an electric vehicle.

Measurement of Multiscale Thermal Transport Phenomena in Li-Ion Cells: A Review

The performance, safety, and reliability of electrochemical energy storage and conversion systems based on Li-ion cells depend critically on the nature of heat transfer in Li-ion cells, which occurs over multiple length scales, ranging from thin material layers all the way to large battery packs. Thermal phenomena in Li-ion cells are also closely coupled with other transport phenomena such as ionic and charge transport, making this a challenging, multidisciplinary problem. This review paper presents a critical analysis of recent research literature related to experimental measurement of multiscale thermal transport in Li-ion cells. Recent research on several topics related to thermal transport is summarized, including temperature and thermal property measurements, heat generation measurements, thermal management, and thermal runaway measurements on Li-ion materials, cells, and battery packs. Key measurement techniques and challenges in each of these fields are discussed. Critical directions for future research in these fields are identified.

Spatial and Temporal Distribution of Escherichia coli on Beef Trimmings Obtained from a Beef Packing Plant

The objective of this study was to determine the immediate source of Escherichia coli on beef trimmings produced at a large packing plant by analyzing the E. coli on trimmings at various locations of a combo bin filled on the same day and of bins filled on different days. Ten 2,000-lb (907-kg) combo bins (B1 through B10) of trimmings were obtained from a large plant on 6 days over a period of 5 weeks. Thin slices of beef with a total area of approximately 100 cm(2) were excised from five locations (four corners and the center) at each of four levels of the bins: the top surface and 30, 60, and 90 cm below the top. The samples were enriched for E. coli in modified tryptone soya broth supplemented with 20 mg/liter novobiocin. The positive enrichment cultures, as determined by PCR, were plated on E. coli/coliform count plates for recovery of E. coli. Selected E. coli isolates were genotyped using multiple-locus variable-number tandem repeat analysis (MLVA). Of the 200 enrichment cultures, 43 were positive by PCR for E. coli, and 32 of these cultures yielded E. coli isolates. Two bins did not yield any positive enrichment cultures, and three PCR-positive bins did not yield any E. coli isolates. MLVA of 165 E. coli isolates (30, 62, 56, 5, and 12 from B6 through B10, respectively) revealed nine distinct genotypes. MLVA types 263 and 89 were most prevalent overall and on individual days, accounting for 49.1 and 37.6% of the total isolates, respectively. These two genotypes were also found at multiple locations within a bin. All nine genotypes belonged to the phylogenetic group A0 of E. coli, suggesting an animal origin. The finding that the trimmings carried very few E. coli indicates an overall effective control over contamination of beef with E. coli at this processing plant. The lack of strain diversity of the E. coli on trimmings suggests that most E. coli isolates may have come from common sources, most likely equipment used in the fabrication process.

Charge boosting effect of cholesterol on cationic liposomes

Cationic liposomes that have been used as drug or gene delivery vehicles can be obtained by mixing cationic surfactants in phospholipid liposomes. Cytotoxicity of cationic molecules is one of the problems of the cationic nanocarriers. Therefore we aimed to formulate highly positively-charged cationic liposomes with low content of cationic surfactant, which have both higher cellular uptake ability and lower cytotoxicity. We have investigated the zeta potential behavior in water/soy bean lecithin/cationic surfactant/cholesterol systems by the changing composition as well as the molecular structure of the cationic surfactant. Mixing of monoalkyl (C12, C16 and C18) and dialkyl (C12 and C18) quaternary ammonium chlorides were increased the zeta potential of liposomes from negative to positive values (more than +50mV). Mixing the cholesterol into the cationic liposomes increased the maximum zeta potential further and also induced the large shift of the negative-positive transition point with respect to the cationic surfactant mixing fraction. It means much less cationic surfactant is needed to obtain highly positively-charged liposomes. The significant cholesterol effects on the zeta potential of liposomes were explained based on the lipid distribution inhomogeneity caused by the increased fluidity of liquid ordered phase membranes and the large critical packing parameter of the negatively-charged lipid.

Critical slowing down and hyperuniformity on approach to jamming.

Hyperuniformity characterizes a state of matter that is poised at a critical point at which density or volume-fraction fluctuations are anomalously suppressed at infinite wavelengths. Recently, much attention has been given to the link between strict jamming (mechanical rigidity) and (effective or exact) hyperuniformity in frictionless hard-particle packings. However, in doing so, one must necessarily study very large packings in order to access the long-ranged behavior and to ensure that the packings are truly jammed. We modify the rigorous linear programming method of Donev etal. [J. Comput. Phys. 197, 139 (2004)JCTPAH0021-999110.1016/j.jcp.2003.11.022] in order to test for jamming in putatively collectively and strictly jammed packings of hard disks in two dimensions. We show that this rigorous jamming test is superior to standard ways to ascertain jamming, including the so-called "pressure-leak" test. We find that various standard packing protocols struggle to reliably create packings that are jammed for even modest system sizes of N≈10^{3} bidisperse disks in two dimensions; importantly, these packings have a high reduced pressure that persists over extended amounts of time, meaning that they appear to be jammed by conventional tests, though rigorous jamming tests reveal that they are not. We present evidence that suggests that deviations from hyperuniformity in putative maximally random jammed (MRJ) packings can in part be explained by a shortcoming of the numerical protocols to generate exactly jammed configurations as a result of a type of "critical slowing down" as the packing's collective rearrangements in configuration space become locally confined by high-dimensional "bottlenecks" from which escape is a rare event. Additionally, various protocols are able to produce packings exhibiting hyperuniformity to different extents, but this is because certain protocols are better able to approach exactly jammed configurations. Nonetheless, while one should not generally expect exact hyperuniformity for disordered packings with rattlers, we find that when jamming is ensured, our packings are very nearly hyperuniform, and deviations from hyperuniformity correlate with an inability to ensure jamming, suggesting that strict jamming and hyperuniformity are indeed linked. This raises the possibility that the ideal MRJ packings have no rattlers. Our work provides the impetus for the development of packing algorithms that produce large disordered strictly jammed packings that are rattler free, which is an outstanding, challenging task.

Actively controlled thermal management of prismatic Li-ion cells under elevated temperatures

This paper reports the experimental study of the active control of the thermal management for prismatic lithium ion (Li-ion) batteries under an elevated thermal environment with temperature above 40°C. To defray the cost of performing experimental study under such conditions while obtaining meaningful data for a multi-cell battery pack with practical relevance, this study developed an experimental setup using a combination of four real Li-ion cells and 12 dummy cells. The dummy cells were fabricated to have the same geometry as the real cells and embedded with controllable heating elements to simulate, respectively, the aerodynamic and thermal behavior of a multi-cell pack. This experimental setup was then placed inside a wind tunnel so actively controlled cooling tests can be performed under well-controlled flow conditions. During the tests, heating power up to 6×104W/m3 was generated by the dummy cells, creating and the maximum environment temperature above 40°C. The major observations obtained from these experiments were twofold. First, besides reducing the experimental cost, the combination of real and dummy cells also offers flexibility to obtain experimental data of a large pack under a variety of conditions for model comparison. Second, a simple on-and-off control strategy was demonstrated to effectively reduce the parasitic power consumption of the cooling systems under the evaluated environmental temperature, even when the Li-ion cells were under dynamic load.

Effective Binding of Methane Using a Weak Hydrogen Bond.

The weak hydrogen bond is an important type of noncovalent interaction, which has been shown to contribute to stability and conformation of proteins and large biochemical membranes, stereoselectivity, crystal packing, and effective gas storage in porous materials. In this work, we systematically explore the interaction of methane with a series of functionalized organic molecules specifically selected to exhibit a weak hydrogen bond with methane molecules. To enhance the strength of hydrogen bond interactions, the functional groups include electron-enriched sites to allow sufficient polarization of the C-H bond of methane. The binding between nine functionalized benzene molecules and methane has been studied using the second order Møller-Plesset perturbation theory to reveal that benzenesulfonic acid (C6H5-SO3H) and phenylphosphonic acid (C6H5-PO3H2) have the greatest potential for efficient methane capture through hydrogen bonding interactions. Both acids exhibit efficient binding potential with up to three methane molecules. For additional insight, the atomic charge distribution associated with each binding site is presented.

Plant genotype influences aquatic‐terrestrial ecosystem linkages through timing and composition of insect emergence

AbstractTerrestrial leaf litter provides aquatic insects with an energy source and habitat structure, and species differences in litter can influence aquatic insect emergence. Emerging insects also provide energy to riparian predators. We hypothesized that plant genetics would influence the composition and timing of emerging insect communities among individual genotypes of Populus angustifolia varying in litter traits. We also compared the composition and timing of emerging insect communities on litter from mixed genotypes of three cross types of a hybridizing cottonwood complex: P. angustifolia, P. fremontii, and their F1 hybrids. Using litter harvested from an experimental common garden, we measured emerging insect community composition, abundance, and production for 12 weeks in large litter packs affixed with emergence traps. Five major findings emerged. (1) In support of the genetic similarity hypothesis, we found that, among P. angustifolia tree genotypes, litter from more closely related genotypes had more similar litter thickness, nitrogen concentrations, decomposition rates, and emerging insect communities. (2) Genetic similarity was not correlated with other litter traits, although the litter fungal community was a strong predictor of emerging insect communities. (3) Litter decomposition rate, which was the strongest predictor of emerging aquatic insect communities, was influenced by litter thickness, litter N, and the litter fungal community. (4) In contrast to strong community composition differences among P. angustifolia genotypes, differences in community composition between P. fremontii and P. angustifolia were only marginally significant, and communities on F1 hybrids were indistinguishable from P. angustifolia despite genetic and litter trait differences. (5) Mixed litter packs muted the genetic effects observed in litter packs consisting of single genotypes. These results demonstrate that the genetic structure of riparian forests can affect the composition and timing of aquatic insect emergence. Because many riparian trees are clonal, including P. angustifolia, large clone size is likely to result in patches of genetically structured leaf litter that may influence the timing and composition of insect emergence within watersheds. Riparian restoration efforts incorporating different tree genotypes could also influence the biodiversity of emerging aquatic insects. Our work illustrates the importance of plant genes for community and ecosystem processes in riparian corridors.

Selective Targeting of Lipid Droplets by Proteins

Lipid droplets (LDs) are organelles that store neutral lipids in cells. LDs have a core of neutral lipids, including triacylglycerols and sterol esters, surrounded by a phospholipid monolayer. LDs can grow dramatically to store neutral lipids in its core, which requires a commensurate increase in the size of the LD membrane. CTP:phosphocholine cytidylyltransferase (CCT) plays a key role in regulating the size of LDs, as it the rate-limiting enzyme in phosphatidylcholine (PC) synthesis, which is a major component of the LD outer coat. CCT has been shown to have a binding preference for LD as opposed to bilayer membranes, although the cause of this preference is not known. Previous studies have shown that large hydrophobic packing defects are key for the binding of amphipathic helices (AH) to membranes. We have studied LDs and bilayer membranes by extensive long time scale molecular dynamics (MD) simulations. In our results, we observe differing properties between LD membranes and bilayer membranes, including an increase in the frequency of large defects in LD membranes. We also find, using μs-long MD simulations, that an increase in the size of hydrophobic lipid packing defects in LDs compared to bilayer membranes plays a large role in the specificity of CCT AH initial binding to membranes as compared to bilayer membranes. Moreover, we frequently observe detachment of CCT from bilayer membranes, suggesting the lack of large hydrophobic defects destabilizes this interaction sufficiently to make binding to bilayers thermodynamically less favorable.