Unique Advantage In Terms Research Articles

On the Design of Broadband Truly Balanced Inductor-Less Differential-to-Single-Ended Converter in CMOS Friendly to Wire-Bond Package

This brief presents a broadband inductor-less differential to single-ended (D2S) converter employing complementary structure with series resistor. The developed D2S converter has a unique advantage in terms of amplitude and phase balance performance, achieving true balance in theory and while maintaining wire-bond package friendliness. The D2S converter is validated in a prototype of broadband driver amplifier (DA) for the transmitter front-end and fabricated in 65 nm CMOS process. The measurement results show an amplitude and phase error of less than 0.2 dB and 1∘, respectively, over a frequency range of 0.1 to 6 GHz. The proposed D2S occupies a core chip area of only 0.04×0.1 mm and consumes 6.5–7.4 mW power from a 1.2 V supply voltage.

XCIST—an open access x-ray/CT simulation toolkit

Objective. X-ray-based imaging modalities including mammography and computed tomography (CT) are widely used in cancer screening, diagnosis, staging, treatment planning, and therapy response monitoring. Over the past few decades, improvements to these modalities have resulted in substantially improved efficacy and efficiency, and substantially reduced radiation dose and cost. However, such improvements have evolved more slowly than would be ideal because lengthy preclinical and clinical evaluation is required. In many cases, new ideas cannot be evaluated due to the high cost of fabricating and testing prototypes. Wider availability of computer simulation tools could accelerate development of new imaging technologies. This paper introduces the development of a new open-access simulation environment for x-ray-based imaging. The main motivation of this work is to publicly distribute a fast but accurate ray-tracing x-ray and CT simulation tool along with realistic phantoms and 3D reconstruction capability, building on decades of developments in industry and academia. Approach. The x-ray-based Cancer Imaging Simulation Toolkit (XCIST) is developed in the context of cancer imaging, but can more broadly be applied. XCIST is physics-based, written in Python and C/C++, and currently consists of three major subsets: digital phantoms, the simulator itself (CatSim), and image reconstruction algorithms; planned future features include a fast dose-estimation tool and rigorous validation. To enable broad usage and to model and evaluate new technologies, XCIST is easily extendable by other researchers. To demonstrate XCIST’s ability to produce realistic images and to show the benefits of using XCIST for insight into the impact of separate physics effects on image quality, we present exemplary simulations by varying contributing factors such as noise and sampling. Main results. The capabilities and flexibility of XCIST are demonstrated, showing easy applicability to specific simulation problems. Geometric and x-ray attenuation accuracy are shown, as well as XCIST’s ability to model multiple scanner and protocol parameters, and to attribute fundamental image quality characteristics to specific parameters. Significance. This work represents an important first step toward the goal of creating an open-access platform for simulating existing and emerging x-ray-based imaging systems. While numerous simulation tools exist, we believe the combined XCIST toolset provides a unique advantage in terms of modeling capabilities versus ease of use and compute time. We publicly share this toolset to provide an environment for scientists to accelerate and improve the relevance of their research in x-ray and CT.

Stability for grain oil content in sorghum (Sorghum bicolor)

Oil content in sorghum [Sorghum bicolor (L.) Moench] grains is an important component in determining sorghum as a functional food. Sorghum has unique advantage in terms of its high tolerance to drought and high temperatures. With its ability to yield high with low inputs, it can be used as an alternative oil source with clinical advantages. Breeding efforts towards identifying end use of specific cultivars are required for increased profitability to the farmers. In the present study, oil content was estimated in 19 genotypes over three locations (Gulberga, Solapur and Hyderabad) which were sown in randomized block design with three replications during post rainy season of 2016-17. Oil content ranged from 3.14–4.76% with the highest value in IS 30466. Germplasm lines, IS 31681, IS 1212, IS 30536, IS 30507, IS 603 and IS 30466 were found better adapted to all test environments with stable mean oil content more than population mean. Significant effects of both genotype and environment were observed for oil content, while genotype × environment interaction was not significant indicating that the genotypes do not show differential response to the environment. Oil content had significant correlation with germ size (r = 0.484), while the associations with 100-seed weight and grain hardness were non-significant. The information generated and the genotypes identified will help in breeding sorghum with high oil content thus enhancing the demand for sorghum as an industrial crop.

Parametric study of solid-solid translucent phase change materials in building windows

Thermal energy storage and solar radiation management are crucial to improve the sustainability and energy efficiency of buildings. Compared with the implementation of phase change materials (PCMs) in opaque components, the energy saving potential of incorporating PCMs in transparent glazing windows is much less studied and not well understood. Here we present a comprehensive parametric study of novel PCM windows for building energy saving with a focus on optimizing and quantitatively distinguishing the contributions from the optical and thermal properties of the PCM, which is particularly useful for the design of solid-solid PCM windows. We investigate a reference commercial office building using EnergyPlus by developing an equivalent model of our PCM window that is compatible with EnergyPlus’s modeling capabilities. Compared with a clear-clear double-pane window, the integration of 3 mm solid-solid PCMs with optimal properties in warm, mixed, and cold climates can respectively save up to 17.2%, 14.0%, and 5.8% energy for the HVAC (heating, ventilation, and air conditioning) system, and 9.4%, 6.7%, and 3.2% energy for the whole building. We also demonstrate that these energy savings are most sensitive to the solar absorptance of PCMs for all three climates. The optimal transition temperature varies with climate and is related to the climate and solar radiation heat gain. Other issues are also briefly discussed, such as hysteresis, window orientations, and the effect of interior lighting. Although the optimal PCM windows show energy saving performance comparable with low-emissivity windows, the PCM windows provide a unique advantage in terms of shifting HVAC loads which can provide benefits to the electrical grid.

Deep learning hybrid model with Boruta-Random forest optimiser algorithm for streamflow forecasting with climate mode indices, rainfall, and periodicity

Long-term forecasting of any hydrologic phenomena is essential for strategic environmental planning, hydrologic and other forms of structural design, agriculture, and water resources management. Climate mode indices, utilising machine learning methods, are frequently considered as predictor variables in order to forecast several different hydrological variables. In this study, a feature selection algorithm based on two different deep learning models, i.e., long short-term memory and a gated recurrent unit, is applied to improve the forecasting capability of streamflow water levels at six gaugingstations in the Murray Darling Basin of Australia. This paper therefore aggregates the significant antecedent lag memory of climate mode indices, rainfall, and the monthly factor based on the periodicity as the predictor variables to attain significantly accurate stream water level forecasts. This novel method identifies an improved relationship between the stream water level and climate mode indices through the aggregation of the significant lagged datasets capturing the historical features to predict the future streamflow water level. The boruta feature selection algorithm (BRF) was then applied in a two phase process before and after attaining the significant lagged inputs to screen the optimum predictor variables. The merits of the forecast models were evaluated through different performance evaluation criteria. The results show that the accumulated significant lagged inputs based on climate mode indices, along with the rainfall and periodicity factors are seen to provide improved forecasting of the SWL over the non-BRF deep learning approaches where no prior feature selection was applied. The hybrid LSTM method (i.e., BRF-LSTM model) achieved a unique advantage in terms of SWL forecasting, particularly attaining over 98% of the predictive errors lying within a band of +/-0.015 m with relatively low relative errors (RRMSE ≈1.30% and RMAE ≈ 0.882%), outperforming all of the benchmark models. It is also found that the periodicity factor has a potential influence on the accuracy of the forecast models for the four monitored study stations. This study concludes that the newly developed hybrid deep learning approaches, coupled with the BRF feature selection, provide improved forecasting performance. The hybrid approach developed in this paper can therefore be used to provide a strong provide predictive response algorithm for the hydrological variables that were influenced by the low-frequency variability of the climate model indices in respect to streamflow water level.

Progress of two-dimensional ferroelectrics in physical and chemical applications

Ferroelectric materials are intriguing and technologically useful because the spontaneous electric polarization is electrically switchable, leading to fascinating properties and wide range of applications such as field effect transistor, non-volatile memories and sensors. In general, the emergence of ferroelectricity requires an asymmetric structure. Previous studies of ferroelectrics have mainly focused on ABO3 perovskite compounds such as BaTiO3, PbTiO3. For technological demands, the size of the devices is decreasing dramatically that conventional ferroelectric materials will suffer from many constraints at nanoscale. For example, when the thickness of ABO3 film falls below a critical value, the ferroelectricity would probably disappear. Therefore, it is essential to search for the low-dimensional materials with stable ferroelectricity. Atomically thin two-dimensional (2D) materials which exhibit abundant electronic, optical and mechanical properties would be ideal candidates and a variety of 2D ferroelectric materials have been proposed accordingly. The first part of this article reviews the recent theoretical and experimental progress of 2D ferroelectric materials. In contrast to conventional 2D materials, 2D ferroelectrics have reversible spontaneous electric polarization which would give rise to an electrostatic potential from the bottom to the top surface. The electrostatic potential difference on two surfaces would lead to distinct band edge alignments and different electron transfer when they are respectively integrated with other materials, thus changing the properties of adjacent layers. On the other hand, switching the polarization direction could change the surface’s charge density, making it possible to modulate the binding strength of adsorbed species. According to the Sabatier principle, the adsorbate-surface binding strength must be optimal to achieve the maximum efficiency. A ferroelectric surface with tunable activity can provide a platform to enhance specific catalytic performance. What’s more, the intrinsic electric field in 2D ferroelectric materials is also beneficial to separate the photo-generated carriers and inhibit their recombination, which are of great importance in photocatalytic reactions. It is worth noting that, the opposite electric polarizations in ferroelectric materials are bistable, which means the electrical switching of these two states is nonvolatile. The states will remain even the external electric field is retracted. Therefore, it is expected that this intrinsic electric field would be an effective way to achieve nonvolatile control of the properties of adjacent materials and reaction activity. To this end, in the middle part, we focus on four respects, namely the effects of ferroelectric polarization on magnetism, electronic properties, gas adsorption and photocatalytic water splitting to show the applications of 2D ferroelectric materials. Up to now, great efforts have been devoted in ferroelectric materials with out-of-plane spontaneous polarization. Compared to out-of-plane ferroelectricity, in-plane ferroelectrics have unique advantage in terms of preventing vertical perturbations. With the rapid progress of the experimental techniques, 2D ferroelectric materials would hold great potential to be applied in a broader range of applications. At last, a brief overview for 2D ferroelectric materials is presented.

Research on calculation methods of ship model self-propulsion prediction

The interactions between ships and propellers interfere with the performance of both. This paper aims to discuss the current methods of modeling ship–propeller interactions using computational fluid dynamics (CFD): the Reynolds Averaged Navier–Stokes equation (RANS) and body force methods. The fully resolved propeller method with the RANS solver, the prescribed body force method, and the boundary element method (BEM) and RANS coupled iterative body force method were used to predict the propulsive performance and calculate the self-propulsion point of a KRISO container ship model. For the RANS-BEM iterative body force method, a new method without nesting iteration is adopted to calculate the self-propulsion point. An additional discussion of self-propulsion factors is presented based on these results. Calculation results showed good agreement with model test results. The RANS method performs better at obtaining detailed flow field information and at analyzing the propeller plane wake fields on a propeller plane. The body force method has a unique advantage in terms of computational efficiency for performance evaluations of both ships and propellers.

Genetic variability and GxE interactions for total polyphenol content and antioxidant activity in white and red sorghums (Sorghum bicolor)

AbstractSorghum has unique advantage in terms of its climate resilience and its grain composition with beneficial bioactive compounds. It is a very good source of bioactive compounds such as polyphenols and antioxidants. Breeding efforts for end‐use identity‐specific genotypes are required for increased profitability to the farmers. In this study, total polyphenol content (TPC) and free radical scavenging activity (FRSA) were estimated in 60 genotypes, comprising of white and red sorghums, over three years each with two replications. TPC ranged from 55.6 mg/100 g to 553.1 mg/100 g with the highest value in IS 30508. The highest antioxidant activity, measured as free radical scavenging activity, was observed in IS 16151. Though in general TPC and FRSA are high in red sorghums, not all red sorghums have high TPC and scavenging activity. Significant effects of genotype and environment were observed for all the characters. Correlation studies indicated the possibility of developing a high yielding line with high antioxidant activity. The information generated aids in identifying donors to develop end‐use specific genotypes that are suitable as functional foods.

AgNi Alloy As a Suitable Barrier Layer Material for NbFeSb-Based Half-Heusler Thermoelectric Modules

As a type of moderate- and high-temperature thermoelectric materials, half-Heusler thermoelectric materials have a unique advantage in terms of their power factors and mechanical properties, and the figure of merit (ZT) of FeNb0.88Hf0.12Sb reaches 1.0 at 600°C. In this paper, after taking into account factors such as electrical conductivity, thermal conductivity, melting point, and metal activity, silver (Ag) was selected as the barrier layer material. The barrier layer and thermoelectric materials were welded together by atomic diffusion using spark plasma sintering. There was no obvious elemental diffusion on the connection surface after sintering, indicating that Ag did not impact the performance of FeNb0.88Hf0.12Sb. However, many cracks appeared on the joint surface during the aging process. In further experiments, we added a small amount of nickel (Ni) into the Ag to achieve a close connection between the barrier layer and FeNb0.88Hf0.12Sb. Moreover, we analyzed the interface of the intermetallic compounds after aging for 192 h, which showed that Ni3Nb and Ni6Nb7 compounds formed at the interface. The contact resistance was tested by a scanning probe method, and the resistivity of the barrier layer was determined to be 0.4 μΩ cm2, which is far less than that of other barrier layers. Moreover, the connection strength was greater than 40 MPa. When Ag0.9Ni0.1 was used as the barrier layer to compose the half-Heusler thermoelectric module, the thermoelectric conversion efficiency reached 7.33%, and there was no significant decrease in efficiency during the cyclic test.

The Re-Emergence and Emergence of Vector-Borne Rickettsioses in Taiwan.

Rickettsial diseases, particularly vector-borne rickettsioses (VBR), have a long history in Taiwan, with studies on scrub typhus and murine typhus dating back over a century. The climatic and geographic diversity of Taiwan’s main island and its offshore islands provide many ecological niches for the diversification and maintenance of rickettsiae alike. In recent decades, scrub typhus has re-emerged as the most prevalent type of rickettsiosis in Taiwan, particularly in eastern Taiwan and its offshore islands. While murine typhus has also re-emerged on Taiwan’s western coast, it remains neglected. Perhaps more alarming than the re-emergence of these rickettsioses is the emergence of newly described VBR. The first case of human infection with Rickettsia felis was confirmed in 2005, and undetermined spotted fever group rickettsioses have recently been detected. Taiwan is at a unique advantage in terms of detecting and characterizing VBR, as it has universal health coverage and a national communicable disease surveillance system; however, these systems have not been fully utilized for this purpose. Here, we review the existing knowledge on the eco-epidemiology of VBR in Taiwan and recommend future courses of action.

Characterization of Inclusions in Evolution of Sodium Sulfate Using Terahertz Time-domain Spectroscopy.

The study of fluid inclusion is one of the important means to understanding the evolution of mineral crystals, and can therefore provide original information of mineral evolution. In the process of evolution, outside factors such as temperature and pressure, directly affect the number and size of inclusions, and thus are related to the properties of crystals. In this paper, terahertz time-domain spectroscopy (THz-TDS) was used to detect sodium sulfate crystals with different growth temperatures, and absorption coefficient spectra of the samples were obtained. It is suggested that the evolution of sodium sulfate could be divided into two stages, and 80°C was the turning point. X-ray diffraction (XRD) and polarizing microscopy were used to support this conclusion. The research showed that THz-TDS could characterize the evolution of mineral crystals, and it had a unique advantage in terms of crystal evolution.

A 100 Hz 3.31 J all-solid-state high beam quality Nd:YAG laser for space debris detecting

With the rapid development of space technology, human activities into space are increasing, thereby producing lots of space debris. And the space debris impact is the major cause for the mechanical damage to the space crafts and the main factor affecting the service life; it even endangers the life safety of the astronauts working outside the spacecraft and pose a threat to the astronomical observation and studies. Thus, the monitoring and early warning of space debris are gradually attracting wide attention. Obviously, laser detection as a good-directivity and strong anti-jamming active detecting means has a unique advantage in terms of a round-the-clock detection. Therefore, the developing of debris-detecting laser beam source becomes the most direct and effective means for increasing the space debris detection accuracy. The laser detecting ability is restricted by the laser beam quality, the pulse energy and the repetition frequency at the same time. The beam quality could affect the ability to detect and recognize space target. The bigger the laser pulse energy, the higher the repetition frequency and the smaller the detectable debris, the stronger the detecting ability will be. A good detection effect could be achieved at 80-100 Hz laser pulse repetition frequency. A further increase of the repetition frequency will greatly increase the difficulty and cost accordingly but the improvement of the detection performance is not obvious at all. Thus, repetition frequency around 100 Hz becomes the best choice for laser space debris detection. Based on the laser diode side-pumped rod-shaped amplifier, a high-repetition-frequency and high-beam-quality of joule level Nd:YAG nanosecond laser for space debris detection is developed in this work. The laser adopts MOPA structure, mainly including single longitudinal mode, pre-amplifier unit, SBS phase-conjugate beam control unit and energy extraction unit. In the energy extraction unit, beam splitting-amplifying-combining is adopted for reducing the thermal effect on beam quality by reducing the working current of the amplifier. Under the condition of 100 Hz high repetition frequency and 10.73 J single pulse energy injected by the single longitudinal mode seed, 3.31 J output energy is gained. The output laser beam has a 4.58 ns pulse width, far field beam spot of 2.12 times the value of the diffraction limit, and 0.87% energy stability (RMS).

Case History of Dehydration-Technology Improvement for HCPF Production in the Daqing Oil Field

Summary High-concentration polymer flooding (HCPF) is an enhanced-oil-recovery (EOR) method that has been used since conventional polymer flooding was applied in the main reservoirs of the Daqing oil field because its higher viscoelasticity can improve the oil-displacement efficiency. However, as a result of more produced hydrolyzed polyacrylamide (HPAM), the oil/water mixture is emulsified easily and separated with more difficulty. In this work, a case history of dehydration technology for HCPF production in the Daqing oil field is reviewed, and a laboratory investigation to assess the emulsification behaviors of HCPF-produced emulsions is conducted. Besides the dehydration-mechanism description of a high-voltage pulsed electrical field, electrostatic-demulsification performance for produced liquid from HCPF production is improved, and the operation parameters are optimized. Recent actual acceptance of the optimization recommendations is presented, and the field-application results are also discussed. The results indicate that dehydration technology for the Daqing oil field has been innovated with the industrialization of the EOR process. Traditional methods of gravity or centrifugal settling are replaced; this upgraded freewater knockout (FWKO) has the functions of adsorption, wetting, collision and coalescence, and oil pretreating for HCPF production. Because it is dominated by periodic vibration as its main mechanism, the pulsed-direct-current (DC) electrostatic-demulsification technique has some advantages in overcoming the obstacles encountered by regular types of electrical-field dehydration processes at strong emulsification stability. Compared with previous dehydration processes having complex alternating-current (AC)/DC electrical fields, the process with a pulsed-DC electrical field shows a unique advantage in terms of emulsified water-separation efficiency, energy conservation, environmental protection, lower labor intensity, and more-stable operation, and the dehydration performance meets the oil-treating standards. As the surface-matching technology of EOR, this improvement in dehydration technology is significant for promoting the construction of an HCPF demonstration project and accelerating petroleum development and production efficiently.

Preparation and Applications of Organotypic Thymic Slice Cultures.

Thymic selection proceeds in a unique and highly organized thymic microenvironment resulting in the generation of a functional, self-tolerant T cell repertoire. In vitro models to study T lineage commitment and development have provided valuable insights into this process. However, these systems lack the complete three-dimensional thymic milieu necessary for T cell development and, therefore, are incomplete approximations of in vivo thymic selection. Some of the challenges related to modeling T cell development can be overcome by using in situ models that provide an intact thymic microenvironment that fully supports thymic selection of developing T cells. Thymic slice organotypic cultures complement existing in situ techniques. Thymic slices preserve the integrity of the thymic cortical and medullary regions and provide a platform to study development of overlaid thymocytes of a defined developmental stage or of endogenous T cells within a mature thymic microenvironment. Given the ability to generate ~20 slices per mouse, thymic slices present a unique advantage in terms of scalability for high throughput experiments. Further, the relative ease in generating thymic slices and potential to overlay different thymic subsets or other cell populations from diverse genetic backgrounds enhances the versatility of this method. Here we describe a protocol for the preparation of thymic slices, isolation and overlay of thymocytes, and dissociation of thymic slices for flow cytometric analysis. This system can also be adapted to study non-conventional T cell development as well as visualize thymocyte migration, thymocyte-stromal cell interactions, and TCR signals associated with thymic selection by two-photon microscopy.

Abstract 489: NGS analysis of the single CTC or DTC isolated and subtyped by the integrated subtraction enrichment and immunostaining-FISH

Abstract Majority of the circulating or disseminated tumor cell (CTC or DTC) detection methodologies rely on existence of epithelial markers (such as EpCAM and/or cytokeratins) on tumor cells. However, highly heterogeneous expression or even absence of EpCAM, and down-regulation of both EpCAM and cytokeratins in CTCs/DTCs during epithelial-mesenchymal transition (EMT) has been reported elsewhere, resulting in significant false negative detection of those uncatchable and invisible CTCs/DTCs. A novel strategy integrating subtraction enrichment which efficiently enriches non-hematopoietic tumor cells shed from various types of solid tumor into biofluid including peripheral blood, bone marrow, ascites, pleural effusion, and cerebrospinal fluid (CSF), with immunostaining-FISH (iFISH), which enables in situ phenotypic immunofluorescent staining of tumor biomarker and chromosomal FISH on the identical tumor cell, has shown its unique advantage in terms of detecting CTCs/DTCs with higher sensitivity and specificity. Diversified CTCs/DTCs could be identified and subtyped upon specific chromosome ploidy and tumor biomarker expression, and each subtype of CTCs/DTCs respectively correlate with therapeutic drug sensitivity or resistance, tumor metastasis or relapse. Whole genome amplification and subsequent next generation sequencing (NGS) analysis performed on the single subtyped breast, pancreatic, gastric and NSCLC cancer CTC or DTC targeted by iFISH, and collected by means of a microscopic cell manipulator is able to reveal ploidy of all the chromosomes and status of either unknown genes or a series of known oncogenes including HER2, Kras, BRAF, etc. It is anticipated that SE-iFISH could guide and promote more significant single cell based genomic and functional analyses of CTCs and/or DTCs. Citation Format: Peter Lin. NGS analysis of the single CTC or DTC isolated and subtyped by the integrated subtraction enrichment and immunostaining-FISH. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 489.

Soft-lithography-enabled fabrication of large numerical aperture refractive microlens array in hybrid SiO2–TiO2 sol-gel glass

This paper describes a low-cost soft-lithography method for building large-numerical-aperture microlenses in hybrid sol-gel glass. The fabrication processes comprise three steps, namely fabrication of large numerical aperture microlens array in photoresist as a master, replication of the master in poly-dimethylsiloxane (PDMS) as elastomeric molds and reproduction of the PDMS replica onto the hybrid sol-gel glass as an end structure. Comparing with the direct UV fabrication in the photosensitive sol-gel glass, the proposed method provides a unique advantage in terms of fabrication freedom in shape and thickness of micro-optical elements in the sol-gel glass. This eliminates the difficulties in direct photolithography in sol-gel glass for arbitrary shapes and great thickness due to ever increasing demands.

The Cambrian "explosion" of metazoans and molecular biology: would Darwin be satisfied?

The origins of metazoan bodyplans and the extent to which they are coincident with the Cambrian "explosion" are both areas of continuing debate. The fossil record has a unique advantage in terms of historical perspective, but remains highly contentious on account of the often controversial interpretations of particular groups (e.g. halkieriids, vetulicolians) and the heavy reliance on "windows" of exceptional preservation (e.g. Chengjiang, Burgess Shale). Molecular and developmental biology offer other unique insights, but may be problematic in terms of conflicting phylogenetic signals and questions revolving around gene co-option, evolution of developmental systems and even convergence. Such topics, far from frustrating the enterprise, actually widen our understanding of the nature of the evolutionary process with the exciting promise of the discovery of more general principles.

Nutrient content of South African red meat and the effect of age and production system

Feeding systems, slaughter age and other production techniques notably influence the nutrient content of red meat. The modernization of the different South African production systems since the previous nutrient composition studies, justifies the necessity to update existing knowledge on the nutritional profile of South African produced beef. In addition, a need was identified to extrapolate the effect of the two different feeding systems (extensive and intensive) on this nutritional profile. Results indicate that the total lipid content of marketable young carcasses (age A, fat code 2) has decreased over time, in line with global health and nutrition trends for leaner foods. With the majority of beef from these young carcasses being produced on intensive grain-based feeding systems, South Africa has a unique advantage in terms of total lipid content of such grain-fed produce. Internationally, grain-fed red meat is in most cases higher in total and saturated fat content compared to grass-fed counterparts, while in South African the opposite was observed. In addition to total fat content, the role of various lipid fractions in human health has often been associated with specific produce positioning and marketing. South African grass-fed beef is significantly higher in healthy omega 3 fatty acids and conjugated linoleic acid, irrespective of degree of fat trimming. From a human nutrition perspective, it should be kept in mind that the total amount of omega 3 fatty acids per edible portion of beef produced in either production system is low in comparison to human dietary recommendations.Keywords: Beef, fatty acids, grain-fed beef, grass-fed beef, physical composition