Slow Feeding Research Articles

Design and Control of Copolymer Composition Distribution in Living Radical Polymerization Using Semi‐Batch Feeding Policies: A Model Simulation

AbstractSummary: Although controlled/living radical copolymerization has been extensively studied, the control of copolymer composition distribution receives little attention. In this paper, taking RAFT copolymerization as an example, we develop a mathematical model and simulate copolymerization systems with various reactivity ratios. It is demonstrated that through semi‐batch operations with programmed profiles of slow monomer feeding rate, precise control over copolymer composition distribution (uniform and designed gradient distributions) along polymer chain can be achieved. It is also found that the semi‐batch operations have lower rates of polymerization than their batch counterparts. The reason for this difference is analyzed, and the magnitude depends on the reactivity ratios and targeted copolymer composition. The improvement of the semi‐batch rate by distributing a part of the initiator amount to the monomer feeding tank is found to be minor.Model‐based design and control over composition distribution of gradient copolymers implemented by semi‐batch operations.magnified imageModel‐based design and control over composition distribution of gradient copolymers implemented by semi‐batch operations.

The coupling performance of photonic crystal fibres in fibre stellar interferometry

Large mode area (LMA), single-mode photonic crystal fibres (PCFs) have the potential to provide significant instrumental advantages in fibre stellar interferometry, due to their broad-band attenuation spectrum, endlessly single-moded performance and very large core size. We investigate the theoretical performance of coupling the telescope point spread function directly into LMA PCFs. We find that a single LMA fibre can replace as many as three step-index fibres for atmospheric seeing characterized by DT/ro≥ 2 with approximately the same coupling performance and a slower feed from the telescope. This could lead to considerable simplification of broad-band fibre interferometers.

Rhythm of engorgement and detachment of Anocentor nitens females feeding on horses

The present study evaluated the engorgement and drop-off rhythms of Anocentor nitens females feeding on horses. Drop-off rhythm was evaluated at 6 h-intervals (06:00, 12:00, 18:00, and 00:00 h) on horses held in stalls or in a pasture. A new method of marking feeding female ticks (the bowknot technique) was developed to evaluate ticks on horses in pasture that attached to different parts of the horse's body. This technique was highly successful, indicating no significant interference on tick engorgement rate or final tick weight, length and reproductive capability. Horses held in the pasture during the summer produced only 28.2% of the tick detachment during the daylight period from 06:00 to 18:00 h. In contrast, 53.4% of the ticks detached during this same 12 h-period during the winter. This difference was probably related to the longer scotoperiod during the winter. Different drop-off rhythms were observed for females attached to different anatomical parts of the horse's body. For example, ticks attached to the ears, perineum, and tail showed similar drop-off patterns, but were different from ticks attached to mane, rump and other body parts. The idiosoma length of the feeding female ticks was individually measured every 6 h until the engorged female detached naturally. The engorgement rate (increase in millimeters of the body length per hour) was evaluated during the last 96 h of parasitism. The highest engorgement rates were observed during the last 24 h of parasitism (≈0.16 mm/h), which were four-fold higher than the engorgement rates of the previous 3 days (≈0.04 mm/h), demonstrating that these lower and higher values corresponded to the slow and rapid feeding phases reported elsewhere. Based on these data, the 6 mm idiosoma length was estimated as the minimal length that would correspond to the time point (i.e. 24 h before detachment) during which ticks would undergo the rapid feeding phase and detach as fully engorged females. When this 6 mm length was tested to estimate the number of engorged females detaching from horses in a period of 24 h, the estimated accuracy varied from 58.5 to 97.7% (mean: 73.3%).

Randomized, Controlled Trial of Slow Versus Rapid Feeding Volume Advancement in Preterm Infants

Randomized, Controlled Trial of Slow Versus Rapid Feeding Volume Advancement in Preterm Infants

The Effects of Body Weight, Dietary Fat, and Feed Withdrawal Rate on the Performance of Broiler Breeders

This research was conducted to determine how different dietary and management systems might benefit hatching egg production for flocks with pullets having different BW. The heavy BW pullets produced 3 more eggs than the light BW group before peak because the heavy BW breeder group produced the first egg and reached 50% production 4 to 5 d earlier. However, the light BW breeders produced an equal number of eggs and gained more weight with a higher percentage of carcass crude protein compared with the heavy and medium BW breeders during the experimental period from 20 to 65 wk of age. Feeding high-fat diets to all BW groups of breeders during the 20- to 65-wk period resulted in more weight gain, larger eggs, and 2.5% more carcass fat than feeding low-fat diets, although the breeders were fed equal calories and amino acids each day. Breeders provided a weekly slow feed withdrawal program after peak production with feed being reduced by 0.16 g/d per breeder gained more weight and produced heavier eggs from 30 to 65 wk of age compared with breeders on a faster feed withdrawal program. The breeders provided the faster feed withdrawal program had feed reduced by 0.64 g/d per breeder for wk 1, 0.33 g/d per breeder for wk 2 and 3, and 0.16 g/d per breeder thereafter. The feed withdrawal programs were stopped when breeders were fed 396 kcal of ME/d per hen. The breeder hens that had feed reduced at a faster rate consumed 5.7 g less feed per egg.

The role of feeding behavior in sustaining copepod populations in the tropical ocean

A fundamental question regarding marine copepods is how the many species coexist and persist in the oligotrophic environment (i.e. Hutchinson's paradox). This question is addressed with a stochastic, object-oriented Lagrangian model that explicitly simulates the distinct foraging behaviors of three prominent tropical species: Clausocalanus furcatus, Paracalanus aculeatus and Oithona plumifera. The model also individually tracks all prey cells. Each particle's motion combines sinking, turbulent diffusion and active swimming when applicable. The model successfully simulates observed size-partitioned carbon uptake rates. Based on the model results, the wide-ranging translational ambit employed by C. furcatus is best suited for the acquisition of passive prey while the relatively stationary behavior of O. plumifera promotes the capture of larger, quickly sinking cells. The model results further suggest that the slow velocities and feeding current employed by P. aculeatus are best suited for acquiring the smallest cells though it also has a slight advantage over C. furcatus in acquiring the largest prey. A resource threshold, at a prey concentration of 530 cells mL -1 , is consistently exhibited by all three modeled species. Overall, these results imply that the size-partition preferences due to their different foraging behavior contribute to the coexistence of these three species.

Rapid Feeding Volume Advancements: Uncertainty About the Effect on Necrotizing Enterocolitis Incidence

To the Editor .— In a recent issue of Pediatrics , Caple et al1 reported on a randomized, controlled trial of slow versus rapid feeding volume advancements in appropriate-for-gestational-age infants between 1000 and 2000 g at birth. The authors presented findings that are in good agreement with prior studies on the same …

Randomized, controlled trial of slow versus rapid feeding volume advancement in preterm infants

Randomized, controlled trial of slow versus rapid feeding volume advancement in preterm infants

Sténose hypertrophique du pylore : comparaison entre deux protocoles de réalimentation postopératoire : « progressif » et « ad libitum »

A recent alternative feeding regimen at the progressive feeding (PF) after a pyloromyotomy for hypertrophic pyloric stenosis (HPS) is the so-called ad libitum feeding (AL). The aim of this study was to determine if this new feeding regimen has modified the follow-up of postoperative course in HPS. Population and methods. – From January 1998 to December 2003, 97 consecutive neonates have been operated on for HPS in our hospital. This retrospective study was based on the comparison between two groups of patients with different postoperative feeding regimens: group one of 30 neonates with PF regimen and group two of 60 neonates with AL regimen. Seven remaining neonates had had a mucosal perforation and were not included in this comparative study but in a separate group (MP). The clinical, ultrasonographic, operative and postoperative data were compared. Results. – There was no difference between the PF and AL groups for sex ratio M/F = 4/1, preoperative weight loss ratio, ultrasonographic data and intra-operative difficulties rate. A small difference was found – which was not significative – between the PF and the AL groups for median age at diagnosis (44,6 v 36,7 days, respectively). A statistically significative difference between the PF and the AL groups was observed for time to establish feeding (69 vs 35.6 hours, respectively) ( P < 0,001), postoperative stay (4.16 vs 2.98 days, respectively) ( P < 0,001) and total hospital charges. We didn’t found any difference in the incidence and severity of postoperative emesis whether slow (PF) or rapid (AL) feeding regimens were used. Furthermore, intra-operative mucosal tear didn’t influence postoperative course and the duration of hospital stay. Conclusion. – We recommend AL regimen for routine feeding in simple cases after pyloromyotomy for HPS. It has a positive impact on length of hospital stay, and decreases hospital charges. Most neonates with MP can be managed with a rapid feeding regimen.

Light emission, chip morphology, and burr formation in drilling the bulk metallic glass

The chip light emission, chip morphology, burr formation and machined surface in drilling of Zr-based bulk metallic glass (BMG) material are investigated. This study demonstrates that the work- and tool-material as well as the feed rate and spindle speed, two drilling process parameters, all affect the onset of chip light emission. Slow feed rate and high spindle speed increase the specific cutting energy and promote the exothermic oxidation and light emission of the chip. Six types of chip morphology, powder, short ribbon, long ribbon, long spiral, long ribbon tangled, and fan, are observed in BMG drilling. The long ribbon tangled chip morphology is unique for BMG material. On the machined surface under quick stop condition, the fracture topography unique to metallic glass with tributary, void, and vein patterns is observed. Different burr formations are observed: the roll-over shape in the entry and the crown shape in the exit edge. The size of burr in the exit edge is typically larger than that in the entrance edge. High feed rate helps to reduce the size of burr in both entrance and exit edges. This study concludes that the WC–Co tool-material, due to its high thermal conductivity and hardness, performs better in drilling BMG than the high speed steel tool.

Randomized, Controlled Trial of Slow Versus Rapid Feeding Volume Advancement in Preterm Infants

To determine whether infants who are fed initially and advanced at 30 mL/kg per day (intervention) take fewer days to get to full feedings than those who are fed initially and advanced at 20 mL/kg per day (control), without increasing their incidence of feeding complications and necrotizing enterocolitis (NEC). We also examined whether these infants regain birth weight earlier, have fewer days of intravenous fluids, and a have shorter hospital stay. A randomized, controlled, single-center trial was conducted in a Neonatal Intensive Care Unit of a community-based county hospital in Houston, Texas. Infants between 1000 and 2000 g at birth, gestational age < or =35 weeks, and weight appropriate for gestational age were allocated randomly to feedings of expressed human milk or Enfamil formula starting and advanced at either 30 mL/kg per day or 20 mL/kg per day. Infants remained in the study until discharge or development of stage > or =IIA NEC. A total of 155 infants were enrolled: 72 infants in the intervention group and 83 in the control group. Infants in the intervention group achieved full-volume feedings sooner (7 vs 10 days, median), regained birth weight faster (11 vs 13 days, median), and had fewer days of intravenous fluids (6 vs 8 days, median). Three infants in the intervention group and 2 control infants developed NEC for an overall incidence of 3.2% (relative risk: 1.73; 95% confidence interval: 0.30-10.06). Among infants between 1000 and 2000 g at birth, starting and advancing feedings at 30 mL/kg per day seems to be a safe practice and results in fewer days to reach full-volume feedings than using 20 mL/kg per day. This intervention also leads to faster weight gain and fewer days of intravenous fluids.

Dorsal fin in the white shark, Carcharodon carcharias: A dynamic stabilizer for fast swimming

Transverse sections of the skin in the dorsal fin of the white shark, Carcharodon carcharias, tiger shark, Galeocerdo cuvier, and spotted raggedtooth shark, Carcharias taurus, show large numbers of dermal fiber bundles, which extend from the body into the fin. The bundles are tightly grouped together in staggered formation (not arranged in a straight line or in rows). This arrangement of dermal fibers gives tensile strength without impeding fiber movement. Tangential sections indicate that the fibers in all three species are strained and lie at angles in excess of 60 degrees . Of the three species investigated the dermal fibers in C. carcharias are the most densely concentrated and extend furthest distally along the dorsal fin. The overall results indicate that the dorsal fin of C. carcharias functions as a dynamic stabilizer and that the dermal fibers are crucial to this role. The fibers work like riggings that stabilize a ship's mast. During fast swimming, when the problems of yaw and roll are greatest, hydrostatic pressure within the shark increases and the fibers around the body, including in the dorsal fin, become taut, thereby stiffening the fin. During slow swimming and feeding the hydrostatic pressure is reduced, the fibers are slackened, and the muscles are able to exert greater bending forces on the fin via the radials and ceratotrichia. In C. carcharias there is a trade-off for greater stiffness of the dorsal fin against flexibility.

Seeded Emulsion Polymerization of Block Copolymer Core−Shell Nanoparticles with Controlled Particle Size and Molecular Weight Distribution Using Xanthate-Based RAFT Polymerization

The work described here has shown for the first time that well-defined core−shell nanostructures with controlled particle size and molecular weight distributions (in which the molecular weight distributions of both blocks are independently controlled using the same RAFT controlling agent) can be prepared in an aqueous environment. These types of nanoparticles can lead the way to more novel and interesting structures in applications for drug delivery, biosensors, and other devices. A poly(methyl methacrylate) (PMMA) seed was used to control the particle size distribution, in which styrene (STY) in the presence of the RAFT agent was polymerized under batch conditions to give polymer particles with an number-average molecular weight (Mn) of 7000 and polydispersity (PDI) of 2. Butyl acrylate (BA) was then polymerized under semibatch conditions into these particles to give an overall Mn of 20 000 and PDI close to 1.3 for the block copolymer, in which greater than 90% block purity was observed. The calculated PDI of the second block (PBA) was close to 1.4, which is lower than the theoretically determined value under batch conditions (PDI = 1.6). The results show that by slow monomer addition feed into the reactor the PDI can be reduced and that by using the advantage of “random coupling” between the two blocks the PDI of the final block copolymer is lower than either of the individual blocks.

Enzymatic Hydrocyanation of a Sterically Hindered Aldehyde. Optimization of a Chemoenzymatic Procedure for (R)-2-Chloromandelic Acid

The asymmetric synthesis of (R)-o-chloromandelic acid, a key intermediate for the anti-thrombotic agent clopidogrel, via the almond meal catalyzed hydrocyanation of 2-chlorobenzaldehyde and subsequent acidic hydrolysis was developed into an industrially viable procedure. The use of a minimum amount of water consistent with enzyme activity and a slow feed of the reactants were the keys to obtaining (R)-2-chloromandelonitrile in a high (98%) yield and satisfactory (90%) enantiomeric excess. Acidic hydrolysis of the nitrile followed by crystallization from toluene afforded enantiopure (ee > 99%) (R)-2-chloromandelic acid.

Synthesis and characterization of titania-coated silica fine particles by semi-batch process

Abstract Monodispersed, spherical titania (TiO2)-coated silica (SiO2) fine particles were synthesized by semi-batch process. By this process, SiO2 fine particles were also prepared and were used as carrier particles for the coating. The mean size of SiO2 particles was 250 nm. The reaction parameters were the concentration of tetraethylorthotitanate (TEOT), the amount of hydroxypropylcellulose (HPC) as a dispersant, the feed rate of starting solution (TEOT+HPC+EtOH) and reaction temperature. As a result, the following results were obtained; particle size of titania-coated silica particles decreased with a decreasing TEOT concentration, slow feed rate and increasing amount of HPC. In addition, it was desirable to maintain a reaction temperature at 15–18 °C in order to obtain the monodispersed fine particles. Consequently, the optimal conditions for the preparation of titania-coated silica particles with narrow size distribution were TEOT (0.03–0.04 M), HPC (0.001–0.0013 g ml−1), feed rate (0.5–0.6 ml min−1), and reaction temperature (15–18 °C). The samples were characterized using FT-IR, EDS, TEM and BET analyzer. The coating thickness of TiO2 particles obtained by using the above conditions was about 5–10 nm.

A serine proteinase inhibitor (serpin) from ixodid tick Haemaphysalis longicornis; cloning and preliminary assessment of its suitability as a candidate for a tick vaccine

Rapid amplification of the cDNA ends (RACE) and primers designed based on a conserved serpin amino acid motif (NAVYFKG) were used to clone a 1350 bp cDNA which encodes a 378 polypeptide with high sequence similarity to several known serpins. We have named this gene as Haemaphysalis longicornis serpin-1 (HLS1). Northern blotting and reverse transcription (RT)-PCR analysis of total RNA from unfed or partially fed whole ticks as well as dissected tick organs revealed that transcription of HLS1 mRNA was induced by blood meal feeding during the slow feeding phase (24–48 h post-attachment) only in the tick midguts. Vaccination of rabbits with recombinant HLS1 (rHLS1) expressed in Escherichia coli resulted in 43.9 and 11.2% mortality of nymph and adult ticks which were fed on immunized rabbits. Polyclonal rabbit antibodies to tick saliva did not react with rHLS1, suggesting that native HLS1 was not secreted into the host during tick feeding. rHLS1 could be a potential candidate for a cocktail anti-tick vaccine.

Fixed abrasive diamond wire machining—part II: experiment design and results

Experimental results from fixed abrasive diamond wire machining of wood and foam ceramics are presented. Three types of wood—pine, oak, and fir, and three types of foam ceramic—silicon carbide, zirconia, and zirconia toughened alumina, are tested. The research investigates the life of diamond wire and effects of process parameters on the cutting forces, force ratio, and surface roughness. A scanning electron microscope is used to study the worn diamond wire, machined surfaces, and debris. The diamond wire saw is demonstrated to be very effective in machining foam ceramics. The wire life for cutting wood at slow feed rates is low. The short tool life for dry cutting of wood indicates that more research in new fixed abrasive diamond wire and wire saw machining technologies is necessary.

Diet immersion time: effects on growth, survival and feeding behaviour of juvenile southern rock lobster, Jasus edwardsii

The effect of water immersion time of a formulated shrimp diet on growth, survival, food conversion and carapace colour of juvenile southern rock lobster, Jasus edwardsii, was determined during a 16 week growth trial. Lobsters were fed one of five diets: pre-soaked shrimp diet (0.5, 2, 4 and 8 h) or non-soaked shrimp diet (0 h). Despite a significant loss in dry matter, protein, ash and astaxanthin from the diet as a result of pre-soaking, there was no effect on the growth, survival, food conversion or carapace colour of lobsters. Feeding behaviour of juvenile J. edwardsii was assessed using glycine, taurine and betaine, previously identified as strong chemoattractants to other crustaceans. Quantification of the antennular grooming frequency (AGF) was identified as the best method of assessing chemoattractant detection in J. edwardsii. The highest rate of AGF was observed in response to glycine at concentrations of 10 −4 to 10 −6 mol l −1. AGF was subsequently used to assess the excitatory capacity of shrimp diet extract and fresh mussel ( Mytilus edulis) extract. Two separate experiments were performed to determine the influence of water immersion on the excitatory capacity (ability to detect the source-(AGF)) and the attractability (capacity to attract to the source-(foraging preference)) of the shrimp diet in comparison to that of fresh mussel flesh. The excitatory capacity of the non-soaked shrimp diet, soaked shrimp diet and fresh mussel extracts were similar. However, the attractability of the non-soaked shrimp diet was greater than soaked shrimp diet and mussel flesh. Lobsters are capable of detecting the shrimp diet regardless of prolonged exposure to water; however, they will selectively move towards a “fresh” rather than a “stale” diet. The results of this study show that the loss of chemoattractants and nutrients from a shrimp diet, caused by leaching, had little impact on the culture performance of J. edwardsii. Thus, even though some lobsters have a slow feeding response and may not feed for several hours after being fed, the dispensation of feed only once per day will not impact on culture performance. However, the influence of leaching on the performance of diets specifically developed for J. edwardsii will need to be re-assessed.

The effects of selection for larval behavior on adult life-history features in Drosophila melanogaster.

Selection for late-life fecundity and longevity in adult Drosophila melanogaster is well known to modify numerous characteristics of life history and physiology. We report experiments here in which selection applied to behavior affects features in an identical fashion. Selection for feeding rate of larval D. melanogaster modifies caloric intake, as measured by the uptake and incorporation of labeled glucose. Selection for slow larval feeding produced lines of D. melanogaster in which larvae synthesized significantly less lipid prior to pupation and eclosed to have low early-life fecundity and a long life as adults. They also had greater lifetime fecundity, but lower viability of egg to hatched adult. Alternatively, fast-feeding larvae incorporated more lipid before pupation and eclosed with high early-fecundity that declined rapidly throughout their short adult life. Slow-feeding populations also had a significantly enhanced expression of the stress-resistance genes CuZn-SOD, CATALASE, and HSP70. Selection on larval feeding behavior reproduced the antagonistic evolutionary trade-off found under selection for adult life span and mimicked the physiological response in life span as seen in many species when dietary restriction is imposed on adults. Thus, nutrient acquisition during development appears to share a common evolutionary and genetic basis with the allocation processes that determine adult life-history traits and the related phenotypic dietary restriction phenomena.

The relationship between ‘critical weight’ and 20-hydroxyecdysone in the female ixodid tick, Amblyomma hebraeum

The feeding cycle of adult female ticks (Acari: Ixodidae) is divided into preparatory, slow and rapid feeding phases. At the transition from slow to rapid feeding, Amblyomma hebraeum (Koch) females reach a ‘critical weight’ (CW; approx. 10× the unfed weight) that is characterized by several behavioural and physiological changes. Five of these changes were used as criteria to establish a more precise estimate of CW than we have to date. The CW as defined by re-attachment to the host was 9× the unfed weight, while for haemolymph ecdysteroid titre, salivary gland degeneration, ovary weight, oocyte length and oocyte vitellin content the CW was 10×, 10×, 12×, 12× and 13×, respectively. CW thus varies depending on the parameter measured. Although previous studies have established the influence of ecdysteroids on salivary gland degeneration and vitellogenesis, here we demonstrate a further effect of ecdysteroids: inhibiting re-attachment to the host.