An assessment of N loss from agricultural fields to the environment in China

Using the 1997 IPCC Guidelines for National Greenhouse Gas Inventory Methodology, and statistical data from the China Agricultural Yearbook, we estimated that the direct N₂O emission from agricultural fields in China in 1990 was 0.282 Tg N. Based on micro-meteorological field measurement of NH₃ volatilization from agricultural fields in different regions and under different cropping systems, the total NH₃ volatilization from agricultural fields in China in 1990 was calculated to be 1.80 Tg N, which accounted for 11% of the applied synthetic fertilizer N. Ammonia volatilization from agricultural soil was related to the cropping system and the form of N fertilizer. Ammonia volatilization from paddy fields was higher than that from uplands, and NH₄HCO₃ had a higher potential of NH₃ volatilization than urea. N loss through leaching from uplands in north China accounted for 0.5–4.2% of the applied synthetic fertilizer N. In south China, the leaching of applied N and soil N from paddy fields ranged from 6.75 to 27.0 kg N ha^-1 yr^-1, while N runoff was between 2.45 and 19.0 kg N ha^-1 yr^-1.     

Nitrous oxide emission from upland crops and crop-soil systems in northeastern China

Although it is known that crops can directly emit N₂O, their contribution to the total N₂O emission from crop-soil systems under field conditions is not well understood. This study was conducted to study the contribution of crops to total N₂O emission from soybean-soil and maize-soil systems in northeastern China. The effects of N fertilization on N₂O emission and NO ₃ ⁻ -N concentration in plants were also studied. The emission from crop-soil systems was measured with the closed chamber method, whereas the direct emission from crops was measured with the soil surface-sealed method. The addition of fertilizer N significantly increased the NO ₃ ⁻ -N concentration in crops and enhanced the N₂O emission from crop-soil systems and from crops alone. The amount of N₂O emitted directly from soybean plants accounted for 6 to 11% of the total soybean-soil emission. Similarly, the amount of N₂O emitted directly from maize plants accounted for 8.5 to 16% of the total maize-soil emission. The proportion of the applied N lost through direct N₂O emission from plants ranged from 0.19 to 0.34%, whereas the proportion of the applied N lost through N₂O emission from the crop-soil system ranged from 1.1 to1.9%. These results suggest that the use of chambers that do not include plants may lead to an underestimation of the total N₂O emission from crop-soil systems. This revised version was published online in November 2006 with corrections to the Cover Date.     

Pathways of acetyl CoA production for lipogenesis from acetoacetate, β-hydroxybutyrate,pyruvate and glucose in neonatal rat lung

The rate of fatty acid synthesis from acetoacetate (AcAc) is 2–3 times greater than from glucose in developing rat lung. To determine the reason for this difference, we investigated the pathways of lipogenesis from [3-¹⁴C] AcAc, [3-¹⁴C]β-hydroxybutyrate (βOHB), [U-¹⁴C] glucose or [2-¹⁴C] pyruvate in minced lung tissue of 3- to 4-day-old rats. The addition of (−)hydroxycitrate, an inhibitor of ATP-citrate lyase, inhibited fatty acid synthesis from glucose, pyruvate, and βOHB by 88%, 70% and 60%, respectively, but had no effect on that from AcAc. Benzene 1,2,3-tricarboxylate, an inhibitor of tricarboxylate translocase, inhibited fatty acid synthesis from all substrates by at least 50%. Incubation with aminooxyacetate, an inhibitor of aspartate aminotransferase, has no effect on lipid synthesis from glucose, pyruvate or AcAc, but increased lipid synthesis from βOHB. Results indicate that for lipid synthesis in the neonatal lung, acetyl CoA from AcAc is derived predominantly from a cytoplasmic pathway involving AcAcCoA synthetase and AcAcCoA thiolase, whereas citrate is the major route of acetyl group transfer from glucose. Lipogenesis from βOHB involves both the cytoplasmic and citrate pathways.     

Chemical Compositions of Oils from Several Wild Almond Species

Chemical compositions of oils extracted from three wild almond species [Amygdalus scoparia from Beyza, Iran (AZ); A. scoparia from Borazjan, Iran (AJ), and A. hausknechtii from the Firuzabad region, (AH)] and a domestic species, A. dulcis from Estahban, Iran (AD), as a reference, were investigated. Total oil content ranged from 44.4% in AJ to 51.4% in AD. Saponification numbers were in the range of 173.5 (for AJ) to 192.9 for AD. Oxidative stability, total phenolic contents and total wax contents were found to be within the ranges 11.7–14.0 h, 33.9–43.2 and 2.05–2.53%, respectively. The main monounsaturated fatty acid (MUFA) was oleic acid ranging from 66.7% for AH to 69.7% for AZ. The only polyunsaturated fatty acid (PUFA) was linoleic acid ranging from 18.2% for AZ to 23.0% for AD. The major saturated fatty acid was palmitic acid. MUFA contents and MUFA to PUFA ratio in the oils from wild almond species as well as those in the domestic one were found at higher levels than those in the common vegetable oils such as soybean, various nut oils, and also those from the seeds of pomegranate, grape, date and sesame. Oils from wild almond species investigated here are rich in oleic acid and can be considered as potential vegetable oils in the human diet.     

Changes in patterns of fertilizer nitrogen use in Asia and its consequences for N2O emissions from agricultural systems

In most soils, formation and emissions of N₂O to the atmosphere are enhanced by an increase in available mineral nitrogen (N) through increased rates of nitrification and denitrification. Therefore, addition of N, whether in the form of organic or inorganic compounds eventually leads to enhanced N₂O emissions. Global N₂O emissions from agricultural systems have previously been related primarily to fertilizer N input from synthetic sources. Little attention has been paid to N input from other N sources or to the N₂O produced from N that has moved through agricultural systems. In a new methodology used to estimate N₂O emissions on the country or regional scale, that is briefly described in this paper, the anthropogenic N input data used include synthetic fertilizer, animal waste (feces and urine) used as fertilizer, N derived from enhanced biological N-fixation through N₂ fixing crops and crop residue returned to the field. Using FAO database information which includes data on synthetic fertilizer consumption, live animal production and crop production and estimates of N input from recycling of animal and crop N, estimates of total N into Asian agricultural systems and resulting N₂O emissions are described over the time period 1961 through 1994.During this time the quantity and relative amounts of different types of materials applied to agricultural soils in Asia as nitrogen (N) fertilizer have changed dramatically. In 1961, using the earliest entry from the FAO database, of the approximately 15.7 Tg of fertilizer N applied to agricultural fields 2.1 Tg N (13.5% of total N applied) was from synthetic sources, approximately 6.9 Tg N from animal wastes, 1.7 Tg N from biological N-fixation, and another 5 Tg N from reutilization of crop residue. In 1994, 40.2 Tg from synthetic fertilizer N (57.8% of total), 14.2 Tg from animal wastes, 2.5 Tg from biological N-fixation and 12.6 Tg from crop residue totalling 69.5 Tg N were utilized within agricultural soils in all Asian countries.The increases in N utilization have increased the emission of nitrous oxide from agricultural systems. Estimated N₂O from agricultural systems in Asia increased from about 0.8 Tg N₂O-N in 1961 to about 2.1 in 1994. The period of time when increases in N input and resulting N₂O emissions were greatest was during 1970–1990.This evaluation of N input into Asian agricultural systems and the resulting N₂O emissions demonstrates the large change in global agriculture that has occurred in recent decades. Because of the increased need for food production increases in N input are likely. Although the rate of increase of N input and N₂O emissions during the 1990s appears to have declined, we ask if this slowed rate of increase is a general long term trend or if global food production pressures will tend to accelerate N input demand and resulting N₂O emissions as we move into the 21st century.     

Magnesite-Spinel products from fused materials with by-products from chemical processes

Conclusions The feasibility was demonstrated of producing chrome-containing magnesia spinel from a mixture of the by-products of chemical processes and magnesite. The composition of this spinel is similar to that of spinel fused from a mixture of commercial alumina, magnesite, and chromite. The fused spinel from the by-products contains a large proportion of SiO₂ and correspondingly less FeO + Fe₂O₃ than spinel fused from commercial alumina.The properties of magnesite-spinel refractories based on fused and sintered spinels from the by-products were investigated and compared with those of specimens based on fused and sintered spinels from alumina. The properties of the products containing fused spinels from the by-products proved to be good and similar to those of products containing fused spinel from alumina.Fused spinel from the by-products can be used also as starting material for the production by the ceramic method of spinel brick with good properties.Translated from Ogneupory, No. 6, pp. 33–39, June, 1974.     

Low-molecular weight organic compositions of acid waters from vegetable oil soapstocks

Alkaline extracts (soapstocks) from canola, corn, cottonseed, peanut, soybean, and sunflower oil refining were acidified, and identities and concentrations of the low-molecular weight organic components of the resulting acid waters were determined by gas chromatography, followed by mass spectroscopy, and by high-performance liquid chromatography. The main components of each acid water sample, in order of decreasing concentration and after omitting the fermentation product lactic acid, were phosphoric acid, α-glycerophosphate, and glycerol from canola;myo-inositol, phosphoric acid, α-glycerophosphate andmyo-inositol-1-phosphate from corn; glycerol, α-glycerophosphate,myo-inositol-1-phosphate, and β-glycerophosphate from cottonseed; phosphoric acid, glycerol, andmyo-inositol from peanut; α-glycerophospho-1-myo-inositol,myo-inositol-1-phosphate, α-glycerophosphate, and glycerol from soybean; and α-glycerophosphate, glycerol,myo-inositol-1-phosphate, and β-glycerophosphate from sunflower.     

Effect of growing area on pigment and phenolic fractions of virgin olive oils of the arbequina variety in Spain

The purpose of this investigation was to study differences in the chlorophyll, carotenoid, and phenolic fractions of virgin olive oils from the Arbequina variety cultivated in different olive growing areas of Spain. Virgin olive oil from Lleida was less heavily pigmented, and these oils showed more negative values for the ordinate a^* (of the CIELAB colorimetric system). Pheophytin a was the major chlorophyll pigment, and lutein was the major component of the carotenoid fraction in all oils analyzed. The chlorophyll a concentration in virgin olive oils from Lleida was 700 μg kg⁻¹, but was 175 μg kg⁻¹ in oils from Jaén, and 200 μg kg⁻¹ in oils from Tarragona. Finally, the chlorophyll a/chlorophyll b ratio was 9 in oils from Lleida and around 0.6 in the other two Arbequina olive oils. In relation to the phenolic fraction, the hydroxytyrosol and tyrosol contents were significantly higher in olive oils from Jaén (grown at higher altitude and precipitation rates). The secoiridoid derivatives showed a significantly higher concentration in olive oils from Tarragona, probably due to the low altitude where they grow, and finally the ratio of (dialdehydic form of elenolic acid linked to tyrosol)/lignans had a value of 1.4 in olive oils from Lleida, whereas this value was around 0.7 in the other Arbequina olive oils.     

Size-controlled synthesis of Fe-Ni alloy nanoparticles by hydrogen reduction of metal chlorides

We synthesized crystalline Fe-Ni nanoparticles with various particle sizes by reducing NiCl₂ and FeCl₂ vapors with hydrogen simultaneously. To control the primary particle size, processing variables of evaporator temperature, reaction zone temperature, and total gas flow rate were varied. The nanoparticles were nearly spherical and formed directional linkage between them due to magnetic interaction. The XRD patterns and elemental compositions measured by EDS showed that the Fe-Ni nanoparticles were mainly composed of cubic FeNi₃. With various evaporation temperatures from 800 to 900 °C, the reactant concentrations were estimated to range from 7.94 × 10^− 6 to 2.68 × 10^− 5 mol/l, which resulted in the specific surface area and Sauter diameter of the particles from 11.1 to 8.8 m²/g and from 65 to 82 nm, respectively. The geometric standard deviations of the primary particle sizes obtained from TEM micrographs ranged from 1.24 to 1.27, indicating very narrow particle size distribution. The increase in the reaction temperature from 850 to 950 °C led to the reduction of the Sauter diameter from 69 to 63 nm. As the total gas flow rate decreased from 5 to 3 l/min, the Sauter diameter increased from 56 to 69 nm.     

Preparation of near net size porous alumina-calcium aluminate ceramics by gelcasting-pore-forming agent processs

In the processing of porous ceramics, shrinkage from green body to sintered compact during drying and sintering is one of the key concerns which affect microstructure and properties of porous ceramics. Through releasing gases from the burning of the pore forming agents, and volume expansion from the formation of low density resultants during sintering, the sintering shrinkage can be effectively compensated and near net size preparation can be achieved. Herein, near net size porous alumina-calcium aluminate ceramics with controllable shrinkage have been prepared using a combination of gelcasting and pore-forming agent process by adjusting the amount of CaCO₃ and polymethyl methacrylate (PMMA) microspheres added. Al₂O₃ and CaCO₃ were used as raw materials, PMMA microspheres were used as pore-forming agent, isobutylene/maleic anhydride copolymer (Isobam104) was used as gelling agent and dispersing agent. The effects of the addition amounts of CaCO₃ and PMMA in the slurry on the phase composition, shrinkage, porosity, and strength of porous alumina-calcium aluminate ceramics were investigated. The results show that as the CaCO₃ addition amount increases from 0 to 20 wt%, the shrinkage of the samples gradually decreases from 7.3% to −1.4%, and the consequent porosity increases from 58% to 66%, while the compressive strength increases from 5.9 to 15.5 MPa. When PMMA content increases from 10 to 50 wt%, the shrinkage of the samples decreases first and then increases, the porosity increases from 51% to 74%, and the compressive strength decreases from 12.5 to 5.3 MPa. The mechanisms for controlling shrinkages during preparation of porous alumina-calcium aluminate ceramics can be attributed to the following aspects: on one hand, gas release from burning of PMMA and decomposition of CaCO₃ during sintering; on the other hand, volume expansion due to the formation of lower density calcium aluminates which come from the reactions between CaO and Al₂O₃. The near net size preparation technique is of great significance for the manufacture of porous ceramics since the subsequent machining cost can be effectively reduced.     

Olfactory Responses of the Predatory Mites (N eoseiulus cucumeris) and Insects (O rius strigicollis ) to Two Different Plant Species Infested with Onion Thrips (T hrips tabaci)

Responses of Neoseiulus cucumeris (a predatory mite) and the predatory insect Orius strigicollis to volatiles associated with two different plant species infested with onion thrips, Thrips tabaci, were examined in a Y-tube olfactometer. Both predators species showed a significant preference for volatiles from infested cucumber leaves without T. tabaci over clean air. However, they were not attracted to volatiles from uninfested cucumber leaves, artificially damaged cucumber leaves, or volatiles from T. tabaci plus their visible products collected from cucumber leaves. These results suggest that both predator species are capable of exploiting herbivore-induced volatiles from T. tabaci-infested cucumber leaves as a foraging cue. Neither predator was attracted to volatiles from uninfested spring onion leaves, infested spring onion leaves without T. tabaci, or volatiles from T. tabaci plus their visible products collected from spring onion leaves. Interestingly, they avoided volatiles from artificially damaged spring onion leaves. A possible explanation for the non-significant olfactory responses of the predator species to spring onion plants with infestation damage of T. tabaci is discussed.     

Δ9 desaturase activity in bovine subcutaneous adipose tissue of different fatty acid compositiondesaturase activity in bovine subcutaneous adipose tissue of different fatty acid composition

Two experiments were conducted to investigate the relationship between Δ⁹ desaturase (stearoyl-coenzyme A desaturase) activity and fatty acid composition in subcutaneous adipose tissue from cattle of different backgrounds. In Experiment 1, subcutaneous adipose tissue samples were taken from carcasses of pasture-fed cattle and feedlot cattle fed for 100, 200, or 300 d. Adipose tissue from pasture-fed cattle had significantly lower total saturated fatty acids and higher total unsaturated fatty acids than feedlot cattle. Desaturase activity correspondingly was 60–85% higher in pasture-fed cattle than in feedlot cattle. There was no difference in the fatty acid composition or desaturase activity among samples from the 100-, 200-, and 300-d feedlot cattle. In Experiment 2, adipose tissue samples were collected from carcasses of feedlot cattle fed for 180 d with either a standard feedlot ration (control group), or a ration containing rumen-protected cottonseed oil (CSO) for the last 70–80 d. Adipose tissue from the CSO-fed cattle was more saturated than that from the control group, having significantly more 18∶0 and less 16∶1 and 18∶1. Correspondingly, adipose tissue from the CSO group had significantly lower desaturase activity. The elevated 18∶2 in adipose tissue from the CSO group confirmed that unsaturated fatty acids (including cyclopropenoid fatty acids) were protected from biohydrogenation. Further studies are needed to determine whether the repression of desaturase activity results from direct inhibition by cyclopropenoic acids or by higher dietary contents of 18∶2.     

Canopy Fruit Location Can Affect Olive Oil Quality in ‘Arbequina’ Hedgerow Orchards

The effect of location of fruit in canopies of hedgerow olive trees (Olea europaea L., cv. ‘Arbequina’) on quality of virgin oil was tested by analyzing oils extracted from different height layers and faces of nine olive hedgerows (6 North–South oriented and 3 East–West). Although sensory attributes were not different, other oil quality parameters may be significantly modified by fruit position. Oils extracted from fruits harvested from higher layers exhibited significantly higher stability against oxidation, along with higher palmitic acid, linoleic acid and phenol contents, but lower oleic acid content. Oils extracted from fruits harvested from East and North facing hedgerows oriented North–South and East–West, respectively, exhibited higher oleic contents and lower saturated and polyunsaturated fatty acid contents. The mean phenol content of oils extracted from fruits from a North–South oriented hedgerow was significantly greater from one of the East–West oriented hedgerows. These findings may be relevant for the design of future olive hedgerows destined for olive oil production.     

<Emphasis Type="Italic">Trans</Emphasis>, saturated,and unsaturated fat in foods in the united states prior to mandatory <Emphasis Type="Italic">trans</Emphasis>-fat labeling

On July 11, 2003, the U.S. Food and Drug Administration published a final rule amending its food-labeling regulations to require that trans FA be declared in the nutrition label of conventional foods and dietary supplements. The effective date of this final rule is January 1, 2006. This places some urgency on increasing the number and types of currently available foods for which there are trans-fat data. Compositional databases on trans fat content of food are currently limited. The purpose of this study was to determine the trans-fat content of a wide range of foods prior to the effective date of the new regulation. AOAC Official Method of Analysis 996.01 was modified for the analysis of trans fat in noncereal products. Food products for analysis were selected on the basis of market share and data from the USDA's 1994–1996 Continuing Survey of Food Intake by Individuals. Foods were purchased from local supermarkets, weighed, hydrolyzed, converted to FAME, and analyzed by GC. The results showed that trans fat (g/100 g fat) ranged from 0.0 to 48.8 in bread, cake, and related products; from 14.9 to 27.7 in margarines; from 7.7 to 35.3 in cookies and crackers; from 24.7 to 38.2 in frozen potatoes; from 0.0 to 17.1 in salty snacks; from 0.0 to 13.2 in vegetable oils and shortenings; from 0.0 to 2.2 in salad dressings and mayonnaises; and from 0.0 to 2.0 in dry breakfast cereals. Serving sizes for the foods included in this survey ranged from 12 to 161 g, and trans-fat levels ranged from 0.0 to 7.2 g/serving. The significant differences in trans-fat content in products within each food category are due to differences in the type of fats and oils used in the manufacturing processes.     

Antisolvent Crystallization of Sulfa Drugs and the Effect of Process Parameters

Abstract

Three sulfa drugs (sulfathiazole, sulfamethizole, and sulfabenzamide) were crystallized using carbon dioxide and water as antisolvents, and the effects of the type of solvent, the crystallization temperature, and the antisolvent injection rate were investigated. Sulfathiazole crystallized in granulate form from acetone, but it was crystallized in acicular form from methanol. Sulfamethizole was crystallized in tabulate form from acetone and as plates from DMF. Sulfabenzamide was precipitated in the form of prisms from acetone and of aciculates from ethyl acetate. As the crystallization temperature increased from 30 to 50°C, the average particle size increased from 6.5 to 10.5 µm for sulfathiazole, 29.5 to 53.1 µm for sulfamethizole, and 33.0 to 59.8 µm for sulfabenzamide. The crystal habit tended to become more needle‐like as the antisolvent injection rate increased. Larger particles were produced when the antisolvent was changed from carbon dioxide to water.     

Morphological and structural features of polyacrylonitrile fibres spun by the dry-wet method

Conclusions -- A technological regime for the preparation of polyacrylonitrile fibres from binary and ternary copolymers has been chosen; these differ from known specimens in having a more uniform cross-sectional structure and a smoother elementary filament surface.-- A considerable difference in crystalline structure of fibres from binary and ternary copolymers which have been spun into a dimethyl sulfoxide—water bath has been shown.-- Fibres from the binary or ternary copolymer which have been spun into a precipitation bath having a large dimethyl sulfoxide content in water are characterized by a lower degree of swelling.-- Shrinkage of fibres from the binary copolymer in the temperature range 200–220°C is twice as small as the shrinkage of fibres from the ternary copolymer.Deceased.VNIIPV. Translated from Khimicheskie Volokna, No. 3, pp. 19–22, May–June, 1991.     

Aquatic Toxicity Effects and Risk Assessment of ‘Form Specific’ Product-Released Engineered Nanomaterials

The study investigated the toxicity effects of ‘form specific’ engineered nanomaterials (ENMs) and ions released from nano-enabled products (NEPs), namely sunscreens, sanitisers, body creams and socks on Pseudokirchneriella subcapitata, Spirodela polyrhiza, and Daphnia magna. Additionally, risk estimation emanating from the exposures was undertaken. The ENMs and the ions released from the products both contributed to the effects to varying extents, with neither being a uniform principal toxicity agent across the exposures; however, the effects were either synergistic or antagonistic. D. magna and S. polyrhiza were the most sensitive and least sensitive test organisms, respectively. The most toxic effects were from ENMs and ions released from sanitisers and sunscreens, whereas body creams and sock counterparts caused negligible effects. The internalisation of the ENMs from the sunscreens could not be established; only adsorption on the biota was evident. It was established that ENMs and ions released from products pose no imminent risk to ecosystems; instead, small to significant adverse effects are expected in the worst-case exposure scenario. The study demonstrates that while ENMs from products may not be considered to pose an imminent risk, increasing nanotechnology commercialization may increase their environmental exposure and risk potential; therefore, priority exposure cases need to be examined.     

Specialist Leaf Beetle Larvae Use Volatiles from Willow Leaves Infested by Conspecifics for Reaggregation in a Tree

Young, gregariously living larvae of the willow leaf beetles Plagiodera versicolora are known to exhibit characteristic aggregation-dispersion-reaggregation behavior and local fidelity to a host tree. In this study, we investigated whether plant volatiles induced by feeding P. versicolora larvae were involved in the reaggregation behavior. Under laboratory conditions, we conducted dual-choice bioassays and found that the first and second instars discriminated between volatiles from leaves infested by larvae and volatiles from uninfested leaves. The discriminative behavior was dependent on both the time leaves were infested and the age of discriminating larvae. First and second instars preferred odor from 1-d-infested leaves to odor from uninfested leaves, whereas third instars (solitary stage) did not discriminate between these volatile blends. Odor from 2-d-infested leaves was preferred to odor from 1-d-infested leaves by first instars, whereas odor from leaves infested for 3 d was not attractive to these very young larvae. Neither was odor of leaves infested for 1 d and then left uninfested for 1 or 2 d attractive to young larvae. The data suggest that the first and second instars use volatiles from a leaf newly infested by conspecific larvae as one of the reaggregation cues. We detected several herbivore-induced compounds in the headspace of the attractive leaves. Among those, a mixture of synthetic (E)-β-ocimene, (Z)-β-ocimene, allo-ocimene, and linalool was found to attract the larvae.     

Particle size studies of supported metal catalysts: a comparative study by X-ray diffraction,EXAFS and electron microscopy

Supported ruthenium and iridium metal catalysts are studied by X-ray diffraction (XRD), EXAFS analysis and transmission electron microscopy (TEM). Estimates of the mean particle size from these techniques range from 20 to 25 Å from XRD, 13 to 16 Å from EXAFS and 25 to 32 Å from TEM. The strengths and weaknesses of these instrumental methods are discussed, as is the intrinsic comparability of these techniques. From a combination of these methods, the average particle size is estimated to be of the order of 20–30 Å.     

Ketone bodies serve as important precursors of brain lipids in the developing rat

Ketone bodies are readily oxidized for energy by extrahepatic tissues. Since oxidation of ketone bodies produces acetyl coenzyme A (AcCoA), and hence could be an important source of immediate precursors for fatty acid synthesis, we investigated, in whole-brain homogenates of developing rats, the preferential utilization of [3-¹⁴C]acetoacetate (AcAc), [3-¹⁴C]β-hydroxybutyrate (β-OHB), and [U-¹⁴C]glucose for production of CO₂ and lipids, including phospholipids, glycerides, cholesterol, and free fatty acids. Throughout the postnatal period, the rate of AcAc oxidation was 2–3 and 2–6 times the rate for β-OHB and glucose, respectively. The eynthesis of lipids from AcAc was 7- to 11-fold higher than from glucose. The brain’s capacity for lipid synthesis from β-OHB was similar to that from AcAc during the first 8 days of life; however, during the next 10 days, the synthesis of lipids from β-OHB decreased to 60% of AcAc-dependent synthesis. The high rate of lipid synthesis from ketone bodies was accompanied by increased activities of cytoplasmic acetoacetyl CoA synthetase and acetoacetyl CoA thiolase in the developing brain. During the entire postnatal development, the proportion of radioactivity claimed by lipids vs. CO₂ from [3-¹⁴C]AcAc was 44–62% vs. 38–56%; from [3-¹⁴C]β-OHB, 50–81% vs. 19–50%; and from [U-¹⁴C]glucose, 14–43% vs. 57–86%. Phospholipids accounted for more than two-thirds of total lipids synthesized from either ketone bodies or glucose, while diglycerides plus cholesterol and free fatty acids accounted for most of the remainder. Addition of glucose to the incubation medium did not alter lipid production from AcAc throughout the suckling period, but moderately depressed energy production in the brain of 16- to 20-day-old rats. It is clear that in cell-free preparations from the brain of developing rats, ketone bodies are preferred over glucose as precursors for both energy and lipids, mainly phospholipids. These results suggest that ketone bodies are important for the growth and development of the brain.