Small Facets Research Articles

Techniques to mitigate membrane displacement for vacuum-membrane solar-dish facets

The prospects of a multifaceted vacuum-membrane solar dish concentrator are considered in this work. The membrane depths of these facets can shift slightly due to varying ambient conditions throughout an operational day, leading to major focal point shifts and a reduced overall efficiency. The purpose of this work was to experimentally investigate different methods of membrane displacement mitigation. A controlled-environment (indoor) enclosure was employed to examine the effects of static ambient conditions, allowing for the independent manipulation of the surrounding pressure and temperature. Various manufacturing techniques were also investigated within the controlled-environment enclosure, which included alterations in pretension, changes in membrane thickness and adjustments to overall facet sizes. Furthermore, outdoor tests were conducted to determine how solar radiation and convection affected membrane displacement as well as to investigate the performance of various membrane depth control strategies using an Arduino Uno microcontroller. The indoor results showed that opting for a small facet would minimize membrane displacement. The results were supported by material tests and a finite element analysis. The outdoor test results indicated that solar radiation and wind affected the internal temperature and consequently also affected the membrane depth. Furthermore, a focus control system maintaining a constant differential pressure across the membrane achieved the required accuracy of ±2 mm membrane displacement limitation. However, another focus control system consisting of a Hall effect module actively monitoring membrane depth emerged as the most effective, with an increase of about 0.09 mm and a decrease of approximately 0.02 mm from an initial depth of 10 mm. This level of stability with a focus control system will ensure that the facet maintains a consistent optical performance, ultimately advancing the reliability and efficiency of low-cost vacuum-membrane technology.

Pursuit of a Dual Degree During Residency Training

Background: The increasing complexity of the health care system is requiring physicians to become more expansive and comprehensive in their knowledge. Public health awareness, biostatistics, and fiscal understanding including medical reimbursements are only small facets of the expertise physicians are needing to understand. Residency programs across the country are starting to permit the incorporation of graduate education into residency curricula. Residents in academic training programs are starting to have the opportunity to pursue a dual degree study in addition to their residency training. Despite the recognized need for well-rounded physicians and growing opportunities for master’s degree education concurrent with residency training, there is a lack of research regarding residents’ interest in pursuing concurrent degrees. Additionally, the resources that institutions offer repertoires needed to support residents during such endeavors are lacking. Objective: The purpose of this study was to elucidate current interest, resource availability, as well as barriers that Obstetrics and Gynecology (OBGYN) residents may come across when considering a dual degree opportunity during their residency. Methods: A comprehensive questionnaire of 28 items was developed by the researchers using a focus group. The innovative survey was sent to the program directors of all ACGME-accredited OBGYN programs in the US in an electronic format. The survey offered anonymity and easy online accessibility while being available for a total of four weeks (during the month of August 2022). A reminder was sent one week prior to the conclusion of data collection. Results: A total of 298 ACGME-accredited OBGYN programs were contacted with 52 individual responses received. The majority of the respondents identified as white females, with all respondents being under the age of 35. A total of 72% of respondents came from combined academic programs or strictly academic programs with 25% of respondents having initiated or completed additional graduate-level degrees at the time of the survey. Most programs did not mention the opportunity of pursuing a dual degree at the time of residency interviews, and over 50% of programs did not permit their residents to pursue another graduate study during their training. Of those permitting such an endeavor, criteria for pursuing the graduate degree included successfully completing the first year of residency and having a ‘passing’ CREOG score, whereas 40% of respondents were unsure of stipulations by their health systems. Regarding the source of the degree, 90% of respondents stated their residency institution did not have the setup or offer a combined dual degree program option, and >75% of respondents reported a lack of tuition reimbursement for such growth opportunities. Whereas 38% of respondents would consider a dual degree option during residency training if available, 51% of those surveyed are interested in pursuing another degree only after residency, with time and cost being the biggest deterrent to pursuing a degree while in residency. Additionally, the platform utilized for the courses - online versus in-person – was another significant factor that plays a role. Regarding growth opportunities, the majority of respondents are interested in leadership roles and believe that supplementing their credentials, ideally with a Masters in Public Health. Conclusion: The increasing demand for physician knowledge outside of clinical medicine has slowly increased throughout the years. As a response, residency programs are beginning to integrate graduate classes and degrees into the training curriculum. Although a majority of residents appear to be interested in pursuing a graduate degree at some point in their career, their biggest concerns during residency include the time needed to devote to their studies and the cost of earning a graduate degree. It is also apparent through the survey that many programs have not been clear regarding the resources they offer for those who are interested in continuing graduate education during residency training. Recognizing the need for physicians to navigate studies outside of clinical medicine, residency programs need to establish more robust pathways for residents to pursue additional graduate education in fields including business, public health, and social work amongst others. Large-scale research will be needed to further investigate how programs can better support their residents’ interests as they diversify their knowledge base to support their clinical decision-making skills.

Fracture mechanism of Ti60 alloy at high temperature in very high cycle fatigue regime and fatigue life prediction

AbstractThis study aimed to investigate the failure mechanism of Ti60 titanium alloy in the high cycle fatigue (HCF) and very high cycle fatigue (VHCF) at 500°C. Ti60 specimens were characterized before and after the 500°C VHCF test, and the fracture surfaces were observed. The results show that there are three different fatigue failure mechanisms at 500°C: (i) equiaxed primary α phase (αp) cleavage, forming small unsmooth facets and rough fracture area (RA), and fusion of non‐adjacent facets to grow into the main crack. (ii) αp grains gather into large grain with triple junction, and large grain slip to form large fusion facet. (iii) Oxide shedding and then cracks form. A dynamic recurrent neural network model is used to predict the fatigue life of Ti60 alloy, 91% of the overall predictions were within the scatter band of 3.0, and 100% were within the scatter band of 5.0.

Impact Toughness Dependent on Annealing Temperatures in 0.16C-6.5Mn Forged Steel for Flywheel Rotors

For the application of forged medium-Mn steels on flywheel rotors, the effect of annealing temperatures from 300 °C to 650 °C on the impact toughness of 0.16C-6.5Mn forged steel was investigated to demonstrate the microstructural characteristics and austenite reverse transformation determining the impact toughness. The results obtained through standard Charpy V-notch impact tests at ambient temperature show that the impact absorbed energy holds at lower than 10 J almost constantly at annealing temperatures of 300 °C to 500 °C, and a representative intergranular fracture is presented. At an annealing temperature of 600 °C, the impact absorbed energy increases to 147 J, with the ductile fracture characteristics showing plenty of fine dimples, and the high impact toughness is attributed to the high volume fraction above 30% and the moderate stability of reverted austenite. Subsequently, the annealing temperature rises higher than 600 °C, the impact absorbed energy decreases, and the fracture morphology shows brittleness characterized by more flat facets of intergranular fractures and small quasi-cleavage facets, presumably corresponding to the insufficient transformation and twinning-induced plasticity effect due to weakening the Mn partitioning from quenched martensite to reverted austenite, which results in lower austenitic stability. Furthermore, the ductile-to-brittle transition temperature (DBTT) of the 0.16C-6.5Mn forged steel annealed at 600 °C, which holds the highest impact absorbed energy, and is explored for the possibility of flywheel rotor application in a service environment. The DBTT reaches −21 °C, obtained through the Boltzmann function, and the impact absorbed energy is approximately 72 J.

An extraordinary improvement in cryogenic toughness of K-TIG welded 9Ni steel joint assisted by alternating axial magnetic field

A keyhole-TIG welding method assisted with alternating axial magnetic field (MF) was proposed to obtain qualified cryogenic toughness joints. The results show that the MF can refine prior austenite grains and establish distinct Ni-rich grain boundaries. Furthermore, the electron back scatter diffraction data demonstrate that the martensite grains have also been refined, and there is a higher density high angle grain boundary (HAGB) in the MF-assisted joint than in the ordinary joint. Under the cryogenic (−196 °C) Charpy V-notch impact test, the MF-assisted joint express a 37 J absorbed energy, which is 300% higher than the 11.7 J of the ordinary joint. This extraordinary increasing in toughness results from the refinement of grains and high density distribution of HAGB, which act as obstacles to crack propagation in cleavage fracture and form small facets on the fracture surface. The MF-assisted welding method has been proven to obtain qualified 9Ni steel joints.

Mechanistic modelling of fatigue nucleation and short crack growth in polycrystalline alloys

This paper proposes an engineering approach at the microstructural scale to the problem of fatigue crack initiation. Initiation of an engineering fatigue crack approximately 0.2–0.4 mm in size is broken down into the separate processes of nucleation of a small facet, and subsequent short crack growth of the facet to an engineering crack. Engineering fatigue models frequently don't consider these processes separately and have difficulty predicting the total initiation life as the distributions of the separate processes are not known. A fundamental approach to modelling initiation life that tries to address these issues has been developed. A combination of crystal plasticity and the extended finite element method are used to model nucleation followed by short crack growth. The crack growth rate is calculated using the local stored energy at the crack tip, crack growth occurs on the crystallographic plane with the largest accumulated slip, thus allowing crack tortuosity to be modelled. A grain boundary hardening model has been developed which reduces the local stored energy available for growth at grain boundaries resulting in growth retardation. The levels of retardation experienced are in agreement with published data for a range of materials. The method has been successfully correlated with fatigue data for coarse grain RR1000.

Investigation on the tunable spectral characteristics of a nanofacet-sandwiched structure

Spectral radiative characteristics of the nanofacet-sandwiched structure can be effectively tailored by tuning the geometric parameters. The finite-difference time-domain (FDTD) method for electromagnetics is employed to numerically predict the spectral transmittance and absorptance of a sandwiched structure with the nanofacets periodically distributed. Compared with the basic case (a classical three-layer planar configuration), changing the pertinent parameters can transform the radiative behavior from transmittance enhancement to absorptance enhancement. The effects of the width and thickness of the nanofacet, the gap between facets and the facet material are discussed respectively. The results indicate that at small facet thickness and width with large gap, the radiative characteristics exhibit a transmittance-enhancement mode (average transmittance of 0.83), and on the contrary, the absorptance-enhancement mode is achieved (peak absorptance of 0.97). The facet thickness, facet width and the gap between facets donate significant influences on the overall transmittance and absorptance, while the matrix thickness has little effect. Besides, the transmittance-enhancement mode is mainly dominated by the structural parameters, almost independent of the facet material. Whereas, the spectral absorptance presents different extra peaks while changing the facet material.

Chiral Seeded Growth of Gold Nanorods Into Fourfold Twisted Nanoparticles with Plasmonic Optical Activity.

A robust and reproducible methodology to prepare stable inorganic nanoparticles with chiral morphology may hold the key to the practical utilization of these materials. An optimized chiral growth method to prepare fourfold twisted gold nanorods is described herein, where the amino acid cysteine is used as a dissymmetry inducer. Four tilted ridges are found to develop on the surface of single-crystal nanorods upon repeated reduction of HAuCl4 , in the presence of cysteine as the chiral inducer and ascorbic acid as a reducing agent. From detailed electron microscopy analysis of the crystallographic structures, it is proposed that the dissymmetry results from the development of chiral facets in the form of protrusions (tilted ridges) on the initial nanorods, eventually leading to a twisted shape. The role of cysteine is attributed to assisting enantioselective facet evolution, which is supported by density functional theory simulations of the surface energies, modified upon adsorption of the chiral molecule. The development of R-type and S-type chiral structures (small facets, terraces, or kinks) would thus be non-equal, removing the mirror symmetry of the Au NR and in turn resulting in a markedly chiral morphology with high plasmonic optical activity.

Fracture toughness of High-Manganese steels with TWIP/TRIP effects

Three high-manganese steels with different carbon contents were investigated in this work, aiming to explore their elastoplastic fracture toughness, fracture micro-mechanisms and microstructural features. J-R curves were obtained according to ASTM E1820-20 by testing C(T) specimens, applying the unloading compliance method to measure crack extension. The TWIP effect (mechanical twinning + dislocation gliding) developed in Steel A and Steel B with carbon contents of 0.84 wt% and 0.54 wt% respectively. On the other hand, Steel C (carbon content of 0.28 wt%), showed strain-induced γFCC → εHCP transformation associated with the TRIP effect. The three steels presented smooth load (P) vs load-line displacement (v) records; i.e., no instability was observed, which allowed the characterization of fracture toughness by means of J-R curves. Fully dimpled fracture surfaces were observed in Steel A and Steel B, whilst Steel C showed small cleavage facets in some sectors that had not indication in the P vs v records. Best performance in terms of fracture behavior was obtained in Steel B and the poorest in Steel C. In addition to the above, the microstructural analysis of the stable crack growth zones in the fractured specimens allowed the identification of several characteristics.

Women's empowerment and intra-household gender dynamics and practices around sheep and goat production in South East Kenya.

Small ruminant production facets like decision-making, ownership, labour allocation, access to- and control over assets are gendered. This study investigates intra-household gender dynamics and practices around sheep and goat production among smallholder farmers in South East region of Kenya. A quantitative study was conducted on 358 dual-headed (married) households to generate gender-disaggregated data on ownership, decision-making and labour allocation around small ruminant production. Qualitative data was collected through focused group discussions to bring out the community perspectives. From the findings, the average number of small ruminants owned by the households as reported by men was slightly higher than women. The average number of small ruminants solely owned by men was significantly higher than by women. Men reported a relatively higher number of jointly owned small ruminants compared to women. More women than men reported that they could give as a gift, sell-off and slaughter jointly owned small ruminants without consulting their spouses. Small ruminants were considered the most important livestock asset in supporting a household’s livelihood by relatively more women than men. Men had more decision-making autonomy over jointly owned small ruminants compared to women. Production tasks around small ruminants such as feeding, watering, selling milk and cleaning housing structures were mostly performed by the women. Qualitative data identified men as the de facto owners of small ruminants with a higher power position in making the important production decisions. The study offers three implications on the design of livestock interventions to empower women, the interventions should ensure that; 1) women are not just owners of livestock assets but also share power and decision-making rights in all aspects of production, 2) production labour is shared equitably between men and women and, 3) women access benefits from livestock production even when animals are owned by men.

Estimation of Convex Polytopes for Automatic Discovery of Charge State Transitions in Quantum Dot Arrays

In spin based quantum dot arrays, material or fabrication imprecisions affect the behaviour of the device, which must be taken into account when controlling it. This requires measuring the shape of specific convex polytopes. We present an algorithm that automatically discovers count, shape and size of the facets of a convex polytope from measurements by alternating a phase of model-fitting with a phase of querying new measurements, based on the fitted model. We evaluate the algorithm on simulated polytopes and devices, as well as a real 2 × 2 spin qubit array. Results show that we can reliably find the facets of the convex polytopes, including small facets with sizes on the order of the measurement precision.

Simulated migration behavior of metastable Σ3 (11 8 5) incoherent twin grain boundaries

Molecular dynamics simulations are used to examine the migration behavior of one incoherent twin, a Σ3 (11 8 5) / (8 11 5) grain boundary. The boundary is known to exhibit non-Arrhenius boundary migration that slows as temperature increases. This behavior is examined in 165 metastable structures of the same boundary and in a large simulation cell where smaller length scales can have less of an effect. The metastable boundaries show diverse migration behaviors from non-Arrhenius to Arrhenius, though the majority of them exhibit non-Arrhenius behavior. The large simulation cell sizes show no dependence on system size, eliminating concerns about the effect of facet nucleation on the migration in periodic simulation cells. However, facet structures play an important role in the migration of the metastable boundaries. Boundaries with larger facets typically migrate faster than those with smaller facets and with defects in the boundary structure.

Volar Lunate Facet Rim Fractures: K-I Classification and Technique.

Background and Purpose It is difficult to capture and safely support a small volar lunate facet (VLF) fragment and obtain sufficient initial fixation. The challenge in treating VLF rim fractures has resulted in various management options. The purpose of this study was to evaluate the clinical and radiological outcomes of a consecutive series of VLF rim fractures of the distal radius treated surgically and to report the Kondo-Imatani (K-I) classification of these fractures, using computed tomography (CT) images and surgical technique, which is termed the Plate buttress and Double tiered subchondral support (PD) technique. Patients and Methods A retrospective review was conducted on 35 patients with VLF rim fractures that included postoperative clinical evaluations, CT images, and radiographs. Description of Technique The PD technique to stabilize the VLF fragment with an anatomical and low-profile volar locking plate (VLP). Results All fractures healed at the final follow-up; Mayo wrist performance score average was 81.7 points (45-100), and the quick disabilities of the arm, shoulder, and hand (quick-DASH) score average was 9.5 points (0-31.8), showing relatively good clinical results. Conclusion VLF rim fragments are not amenable to standard VLP fixation. Unstable fixation may result in postoperative correction loss, aseptic necrosis, malunion, radiocarpal subluxation, and wrist dysfunction. This report described the K-I classification for VLF rim fractures of the distal radius and surgical technique, termed the PD technique, to stabilize the VLF rim fragment with an anatomical and low-profile VLP. Level of Evidence This is a Level IV, case series study.

Management of Malpositioned Cervical Interfacet Spacers: An Institutional Case Series

IntroductionPosterior cervical foraminotomy and anterior cervical discectomy and fusion (ACDF) are the mainstay treatments for cervical radiculopathy. A recent alternative or adjunct involves the placement of interfacet spacers, which promote indirect decompression by increasing foraminal height. Cervical interfacet spacers have been shown to be safe options for indirect decompression and improve short-term clinical outcomes in patients with cervical spine pathologies. However, no previous data regarding malpositioned spacers and their management have been reported. Given this paucity of data, we aim to present examples of malpositioned interfacet spacers and their management.MethodsThis was a retrospective single-center review.ResultsTwenty-five patients were identified in which interfacet spacers were used at a single level in 19 cases, two levels in five cases, and three levels in one case. The cohort had a mean follow-up of 14.4 months. Among 60 total spacers placed, two required repositioning (3.3%). The first underwent bilateral placement at C4/5 and developed a unilateral deltoid palsy postoperatively. She was taken back to the operating room the same day for implant removal. A second patient underwent removal after a malpositioned implant at C4/5 was identified on an intraoperative CT scan. A third patient had spacers placed at a referring hospital and presented with progressive neck pain and radiculopathy. She underwent successful removal with a resolution of her symptoms.ConclusionsInterfacet spacers represent a novel technique for the treatment of cervical radiculopathy, however, there are limited data on their utilization. We present the first reports of malpositioned spacers and their management. Patients with small facet joints and lateral masses may be at increased risk for malposition, and intraoperative fluoroscopy may not adequately confirm implant placement. Surgeons should use caution when implementing new technology with a low threshold for intraoperative CT to confirm the appropriate placement of these devices.

Geometric Simplifications of Natural Caves in Ray-Tracing-Based Propagation Modelling

Natural caves show some similarities to human-made tunnels, which have previously been the subject of radio-frequency propagation modelling using deterministic ray-tracing techniques. Since natural caves are non-uniform because of their inherent concavity and irregular limestone formations, detailed 3D models contain a large number of small facets, which can have a detrimental impact on the ray-tracing computational complexity as well as on the modelling accuracy. Here, we analyse the performance of ray tracing in repeatedly simplified 3D descriptions of two caves in the UK, i.e., Kingsdale Master Cave (KMC) Roof Tunnel and Skirwith Cave. The trade-off between the size of the reflection surface and the modelling accuracy is examined. Further, by reducing the number of facets, simulation time can be reduced significantly. Two simplification methods from computer graphics were applied: Vertex Clustering and Quadric Edge Collapse. We compare the ray-tracing results to the experimental measurements and to the channel modelling based on the modal theory. We show Edge Collapse to be better suited for the task than Vertex Clustering, with larger simplifications being possible before the passage becomes entirely blocked. The use of model simplification is predominantly justified by the computational time gains, with the acceptable simplified geometries roughly halving the execution time given the laser scanning resolution of 10 cm.

Shaping an optical dome: The size and shape of the insect compound eye

The insect compound eye is the most abundant eye architecture on earth. It comes in a wide variety of shapes and sizes, which are exquisitely adapted to specific ecosystems. Here, we explore the organisational principles and pathways, from molecular to tissular, that underpin the building of this organ and highlight why it is an excellent model system to investigate the relationship between genes and tissue form. The compound eye offers wide fields of view, high sensitivity in motion detection and infinite depth of field. It is made of an array of visual units called ommatidia, which are precisely tiled in 3D to shape the retinal tissue as a dome-like structure. The eye starts off as a 2D epithelium, and it acquires its 3D organisation as ommatidia get into shape. Each ommatidium is made of a complement of retinal cells, including light-detecting photoreceptors and lens-secreting cells. The lens cells generate the typical hexagonal facet lens that lies atop the photoreceptors so that the eye surface consists of a quasi-crystalline array of these hexagonal facet-lenses. This array is curved to various degree, depending on the size and shape of the eye, and on the region of the retina. This curvature sets the resolution and visual field of the eye and is determined by i) the number and size of the facet lens – large ommatidial lenses can be used to generate flat, higher resolution areas, while smaller facets allow for stronger curvature of the eye, and ii) precise control of the inter facet-lens angle, which determines the optical axis of the each ommatidium. In this review we discuss how combinatorial variation in eye primordium shape, ommatidial number, facet lens size and inter facet-lens angle underpins the wide variety of insect eye shapes, and we explore what is known about the mechanisms that might control these parameters.

714 UTILITY, TECHNIQUES, AND OUTCOMES FOR THORACIC DRAINAGE AFTER OESOPHAGECTOMY: A SYSTEMATIC REVIEW

Abstract The routine use of post-operative drains in surgery continues to evolve as part of modern practices. Modern enhanced recovery protocols eschew using abdominal drains due to their impact on patient comfort, mobility, and recovery. This change in practice has not applied to thoracic drainage after oesophagectomy, where one or multiple drains are routinely placed. The aim of this study was to determine the evidence for, and how best to use drains during oesophageal surgery. Methods A systematic literature search was performed in Medline, Embase and Cochrane collaboration databases until Jan 25th, 2021. All studies which compared outcomes for different types or uses of thoracic drainage, or reported outcomes directly related to chest drains in oesophageal surgery were included. Studies were collated into domains based on variations in number, position, type, removal criteria, diagnostic use and complications of drains. Methodological quality was assessed by the Newcastle-Ottawa and Jadad Scores. Results 28 studies met the inclusion criteria. Four studies compared drain numbers, three showed similar outcomes and pain reduction using one. A single study showed that another, ‘anastomotic drain’ aided diagnosis and reduced leak mortality. Transhiatal drains had less pain and similar outcomes compared to intercostal drains. Drain fluid amylase aids leak diagnosis, however, accuracy requires drains to remain for 6 days. Removal of drains with daily volumes of less than 300 mL did not impact effusion rate. Complications can arise from drains with a 7% chance of drains migrating into the lumen of a leak and a risk of drain-site metastasis. Conclusion Drain use is a small facet of oesophageal surgery that can have a significant impact on outcomes. There is no evidence for non-drain use. A single transhiatal drain reduces pain without impacting on outcomes. Drains can have a role in diagnosing and managing anastomotic leaks, however, to be accurate drains have to stay in situ for longer. This extends patients discomfort and moves away from ERP trends and other surgical specialities.

Investigation on growth of the orientation-preferred Cu6Sn5 on (001)Cu during the temperature-increased multiple reflow process

The preferred orientation of Cu6Sn5 formed on (001) Cu single crystals has attracted great attention due to its feature of strong anisotropy. Lots of researchers believe that the formation of preferred orientation is closely related to the reaction temperature but do not have a unified conclusion. In this study, a temperature-increased multiple reflow process was designed and utilized to investigate the grain rotation and coarsening behavior of orientation-preferred Cu6Sn5 formed at the Sn-3Ag/(001)Cu interface. Results demonstrate that the temperature-increased multiple reflow process facilities the annexation and rotation of Cu6Sn5 grains as well as their morphology transformation from scalloped-type to small facet. The results have significant meaning in understanding and controlling the formation of Cu6Sn5 preferred orientation and improving the reliability of solder joints.

Structural and compositional analysis of (InGa)(AsSb)/GaAs/GaP Stranski\u2013Krastanov quantum dots

We investigated metal-organic vapor phase epitaxy grown (InGa)(AsSb)/GaAs/GaP Stranski–Krastanov quantum dots (QDs) with potential applications in QD-Flash memories by cross-sectional scanning tunneling microscopy (X-STM) and atom probe tomography (APT). The combination of X-STM and APT is a very powerful approach to study semiconductor heterostructures with atomic resolution, which provides detailed structural and compositional information on the system. The rather small QDs are found to be of truncated pyramid shape with a very small top facet and occur in our sample with a very high density of ∼4 × 1011 cm−2. APT experiments revealed that the QDs are GaAs rich with smaller amounts of In and Sb. Finite element (FE) simulations are performed using structural data from X-STM to calculate the lattice constant and the outward relaxation of the cleaved surface. The composition of the QDs is estimated by combining the results from X-STM and the FE simulations, yielding ∼InxGa1 − xAs1 − ySby, where x = 0.25–0.30 and y = 0.10–0.15. Noticeably, the reported composition is in good agreement with the experimental results obtained by APT, previous optical, electrical, and theoretical analysis carried out on this material system. This confirms that the InGaSb and GaAs layers involved in the QD formation have strongly intermixed. A detailed analysis of the QD capping layer shows the segregation of Sb and In from the QD layer, where both APT and X-STM show that the Sb mainly resides outside the QDs proving that Sb has mainly acted as a surfactant during the dot formation. Our structural and compositional analysis provides a valuable insight into this novel QD system and a path for further growth optimization to improve the storage time of the QD-Flash memory devices.

Dental wear patterns reveal dietary ecology and season of death in a historical chimpanzee population.

Dental wear analyses have been widely used to interpret the dietary ecology in primates. However, it remains unclear to what extent a combination of wear analyses acting at distinct temporal scales can be beneficial in interpreting the tooth use of primates with a high variation in their intraspecific dietary ecology. Here, we combine macroscopic tooth wear (occlusal fingerprint analysis, long-term signals) with microscopic 3D surface textures (short-term signals) exploring the tooth use of a historical western chimpanzee population from northeastern Liberia with no detailed dietary records. We compare our results to previously published tooth wear and feeding data of the extant and continually monitored chimpanzees of Taї National Park in Ivory Coast. Macroscopic tooth wear results from molar wear facets of the Liberian population indicate only slightly less wear when compared to the Taї population. This suggests similar long-term feeding behavior between both populations. In contrast, 3D surface texture results show that Liberian chimpanzees have many and small microscopic wear facet features that group them with those Taї chimpanzees that knowingly died during dry periods. This coincides with historical accounts, which indicate that local tribes poached and butchered the Liberian specimens during dust-rich dry periods. In addition, Liberian females and males differ somewhat in their 3D surface textures, with females having more microscopic peaks, smaller hill and dale areas and slightly rougher wear facet surfaces than males. This suggests a higher consumption of insects in Liberian females compared to males, based on similar 3D surface texture patterns previously reported for Taї chimpanzees. Our study opens new options for uncovering details of feeding behaviors of chimpanzees and other living and fossil primates, with macroscopic tooth wear tracing the long-term dietary and environmental history of a single population and microscopic tooth wear addressing short-term changes (e.g. seasonality).