Origin of age softening in the refractory high-entropy alloys.

Refractory high-entropy alloys (RHEAs) are emerging materials with potential for use under extreme conditions. As a newly developed material system, a comprehensive understanding of their long-term stability under potential service temperatures remains to be established. This study examined a titanium-vanadium-niobium-tantalum alloy, a promising RHEA known for its superior high-temperature strength and room-temperature ductility. Using a combination of advanced analytical microscopies, Calculation of Phase Diagrams (CALPHAD) software, and nanoindentation, we investigated the evolution of its microstructure and mechanical properties upon aging at 700°C. Trace interstitials such as oxygen and nitrogen, initially contributing to solid solution strengthening, promote phase segregation during thermal aging. As a result of the depletion of solute interstitials within the metal matrix, a progressive softening is observed in the alloy as a function of aging time. This study, therefore, underscores the need for a better control of impurities in future development and application of RHEAs.

Comparison of maternal milk ejection characteristics during pumping using infant-derived and 2-phase vacuum patterns.

Background: Milk ejection characteristics remain consistent throughout 12 months of lactation in women who expressed breastmilk with an electric breast pump. In addition these characteristics appear to remain constant when women are breastfeeding or pumping suggesting that milk ejection is a robust physiological response. It is not known whether the stimulation of an infant at the breast in the early post partum period influences milk ejection patterns or whether this is a programmed event. However, as more data become available on the mechanisms involved in infant feeding, pumping patterns mimicking the infant more closely may provide enhanced results. The objective of this study was to compare milk ejection characteristics obtained when using a novel infant-derived pumping pattern with an established 2-phase pattern. Methods: A convenience sample of ten lactating mothers, 1 to 40 weeks of lactation with normal milk production were recruited in 2015. Each participated in two pumping sessions in which either a 2-phase pattern or infant-derived pattern were randomly assigned. Milk volume and milk ejection characteristics were recorded and the percentage of available milk removed (PAMR) was calculated. Statistical analysis used linear mixed effects modeling to determine any differences between breasts and pump patterns with the consideration of individual variability as a random effect. Results: The number of milk ejections and milk ejection characteristics did not differ between patterns. Milk volumes removed were 53.6 ± 28.5 ml (PAMR 58.2 ± 28.4) for the 2-phase pattern and and 54.2 ± 26.3 ml (PAMR 52.2 ± 22.3) for the infant derived pattern. Peak milk flow rates were positively associated with the available milk (p = 0.0003) and PAMR (p = 0.0001), as was the volume of milk removed during each milk ejection (p = 0.001 and p = 0.0001). Conclusion: An experimental pumping pattern designed to resemble infant sucking characteristics did not alter milk ejection characteristics or milk removal parameters compared with an established 2-phase pattern. Theses findings provide further evidence that milk ejection is a robust physiological response.

Thermal physiology of the lactating nipple influences the removal of human milk.

The nipple has a critical role in successful breastfeeding. Nipple trauma or pain may negatively impact breastfeeding duration which has significant public health implications. The aim of this study was to examine changes in nipple temperature during breastfeeding and pumping within participants. Thirty lactating women participated in two pumping (electric breast pump) and one breastfeeding session. Nipple temperature of both breasts was monitored for two minutes before and after each session with the non-pumped/non-suckled nipple temperature recorded throughout each session. The mean increase in nipple temperature after milk removal by the infant was 1.0 ± 1.6 °C (range -3.2-3.2) and after expression was 1.8 ± 1.4 °C (range -0.9-6.1). Nipple temperature pre expression was significantly lower than post expression (Pre 32.6 ± 1.6, Post 34.3 ± 1.3, p < 0.001) with no difference between the two pumping sessions. For every 1 °C rise in temperature an additional 10 mL of milk was removed on average. The breastfed nipple temperature was significantly lower pre feed than post feed (Pre 32.4 ± 1.6, Post 33.2 ± 1.2 p = 0.01) with a significant but smaller change in nipple temperaturecompared to pumping (Breastfeed 1.0 ± 1.6, Pumping 1.7 ± 1.4, p = 0.03). Nipple temperature increases during pumping and breastfeeding suggesting the breasts have a similar physiological response to different stimuli. Further, the increased temperature potentially plays a role in effective milk removal.

Maternal and Infant Health in Abu Dhabi: Insights from Key Informant Interviews.

Consequent upon rapid development in Abu Dhabi, there has been a rise in chronic disease, the susceptibilities to which are influenced by events occurring in early life. Hence, maternal and infant health are key areas in public health policy. Following a study of maternal and infant health in a cohort of mothers in Abu Dhabi between 2002 and 2004, seven key informant interviews were undertaken to elucidate the study findings through the impressions of Emirati women in positions within the healthcare area-including ministries, hospitals, and universities in Abu Dhabi. Semi-structured interviews were based on five key questions that covered the cultural responsiveness of the maternal health services-breastfeeding, health education, and physical and recreational activity. The responses were analysed using a thematic content technique and indicated that the status of women, cultural beliefs and practices, limited health knowledge, and language differences between the local population, healthcare providers, and health promoting materials were important themes. The study highlighted areas for future research and policy, including the communication gaps between healthcare professionals and women, the influences of advertising and the media on health issues, heath education, and ways to increase women's participation in physical exercise. It is vital to consider non-medical determinants of health alongside biomedical determinants, to help develop culturally appropriate health strategies for this population.

Detection of Milk Ejection Using Bioimpedance Spectroscopy in Lactating Women during Milk Expression Using an Electric Breast Pump.

Milk ejection is essential for effective milk removal during breastfeeding and pumping, and for continued milk synthesis. Many women are unable to accurately sense milk ejection to determine whether their infant is receiving milk or, when pumping, to switch the pump to a more effective expression pattern. To determine if changes in bioimpedance parameters are associated with milk ejection in the lactating breast during pumping. 30 lactating women participated in 2 pumping sessions within 2 weeks of each other. During pumping the breasts were monitored with bioimpedance spectroscopy (on either the pumped or the non- pumped breast), and milk flow rate and volume were measured simultaneously. All mothers completed 24-h milk productions. Linear mixed effects models were used to determine associations between milk flow rate and bioimpedance changes. Changes in bioimpedance parameters were greater at the first milk ejection when measured on the pumped breast (median (IQR): R zero: -7 (-17, -4,) % (n = 30); R infinity: -8 (-20, -2) % (n = 29); membrane capacitance: -24 (-59, -7) % (n = 27). Changes in bioimpedance detected in the non-pumped breast were lower at the first milk ejection, R zero: -3 (-8, -2) % (n = 25); R infinity: -5 (-8, -2) % (n = 23); membrane capacitance: -9 (-17, 15) % (n = 24). Smaller less consistent decreases in the bioimpedance characteristics were detected at the second milk ejection in both breasts. Bioimpedance parameters showed a consistent decrease associated with the first milk ejection when electrodes were placed on the pumped breast. Smaller decreases were observed when the non-pumped breast was monitored for the first and second milk ejection. There was wide variation in the magnitude of changes observed, and hence further development of the methodology is needed to ensure reliability.

Changes in R0/R∞ ratio and membrane capacitance are associated with milk removal from the breast.

Perceived low milk supply is a common reason for introducing supplementary feeds, which in turn serves to further diminish the milk supply. Current methods of measuring milk production and milk transfer from the breast to the infant are inaccessible to the mothers. There is a need for an inexpensive, portable device to enable mothers to measure milk transfer to either confirm their milk production is adequate or identify breastfeeding issues early. The aim of this study was to examine changes in bioimpedance spectroscopy associated with milk removal from the human lactating breast using an electric breast pump. Thirty lactating women participated in 2 research sessions performed in random order over 2 weeks. Milk flow rate and volume were measured during pumping. All mothers completed 24-hour milk profiles. Breasts were monitored using bioimpedance spectroscopy. Analysis was performed using linear mixed effects models to investigate the relationship between both proportional change in membrane capacitance (Cm) and R0/R∞ with milk removal. There was an inverse relationship between R0/R∞ and milk removed (p<0.001). A positive relationship was also observed between Cm and both volume of milk removed (P<0.001) and percentage of available milk removed (p<0.001). This study has shown that changes in bioimpedance are related to the volume of milk removed from the breast during pumping. This modality may hold promise for the measurement of the effectiveness of the breastfeeding infant in removing milk from the breast.

Comparison of Inductively Coupled Plasma Optical Emission Spectrometry with an Ion Selective Electrode to Determine Sodium and Potassium Levels in Human Milk.

Sodium (Na), potassium (K), and the ratio Na:K in human milk (HM) may be useful biomarkers to indicate secretory activation or inflammation in the breast. Previously, these elements have been measured in a laboratory setting requiring expensive equipment and relatively large amounts of HM. The aim of this study was to compare measurements of Na and K in HM using inductively coupled plasma optical emission spectrometry (ICP-OES) with small portable ion selective electrode probes for Na and K. Sixty-five lactating women donated 5 mL samples of HM. Samples were analyzed with two ion selective probes (Na and K) and also ICP-OES. The data were analyzed using paired t-test and Bland⁻Altman plots. Na concentrations were not significantly different when measured with ion selective electrode (6.18 ± 2.47mM; range: 3.59⁻19.8) and ICP-OES (5.91 ± 3.37 mM; range: 2.59⁻21.5) (p = 0.20). K concentrations measured using the ion selective electrode (11.7 ± 2.21 mM: range: 7.69⁻18.1) and ICP-OES (11.1 ± 1.55 mM: range: 7.91⁻15.2) were significantly different (p = 0.01). However, the mean differences of 0.65 mM would not be clinically relevant when testing at point of care. Compared to ICP-OES, ion selective electrode is sufficiently accurate to detect changes in concentrations of Na and K in HM associated with secretory activation and inflammation in the mammary gland.

Hourly Breast Expression to Estimate the Rate of Synthesis of Milk and Fat.

Objective measurement of the rate of synthesis of breast milk and fat in breastfeeding mothers requires test-weighing of each breastfeed and the measurement of each expression from each breast over 24 h, with the collection of milk samples before and after each breastfeed and expression. We sought an abbreviated technique for measuring these rates of synthesis. Participants completed a 24-h breastfeeding milk profile, and expressed their breasts on arrival at the research room and each hour thereafter for 3 h (4 expressions). The hourly rate of milk synthesis, as measured by the yield of milk from the fourth expression, was closely related to the hourly rate of milk synthesis calculated from the 24-h milk profile. The hourly rate of fat synthesis, calculated from the fat content of small samples of the first and last milk expressed during the fourth expression, was different from the rate of fat synthesis calculated from the fat content and volumes of all the breastfeeds and expressions during the 24-h milk profile. The study confirms the use of an abbreviated technique to measure the rate of breast milk synthesis, but is not reliable as a measure of the rate of fat synthesis for an individual.

Normal Human Lactation: closing the gap.

With the exception of infant growth, there are no well-defined parameters describing normal human lactation. This represents a major gap in the continuum of care that does not exist for other major organs. Biological normality occurs naturally and is characterized by well-integrated function. We have proposed a definition that highlights four key elements that describe parameters for biological normality: comfort, milk supply, infant health, and maternal health. Notwithstanding the current limitations, published data have been collated to provide preliminary markers for the initiation of lactation and to describe objective tests once lactation is established. Reference limits have been calculated for maternal markers of secretory activation, including progesterone in maternal blood and total protein, lactose, sodium, and citrate in maternal milk. Objective measurements for established lactation, including 3-hourly pumping and 24-hour milk production, together with pre-feed to post-feed milk fat changes (a useful indicator of the available milk removed by the infant) have been outlined. Considered together with the parameters describing normal function, this information provides a preliminary objective framework for the assessment of human lactation.

Observations on the health of infants at a time of rapid societal change: a longitudinal study from birth to fifteen months in Abu Dhabi.

BACKGROUND: Rapid economic and cultural transition in the United Arab Emirates has been accompanied by a rise in chronic disease. Early childhood is known to affect health outcomes in adulthood. This prospective longitudinal study examined the general health of Emirati infants born in a government maternity hospital in the Emirate of Abu Dhabi in October 2002. METHODS: One hundred twenty-five women, who had recently given birth, were interviewed as part of a larger study encompassing a wide range of cultural, social, and behavioural aspects of health. They were then re-interviewed at three (n = 94), six (n = 59) and 15 months postpartum (n = 52). Data are presented using univariate statistics. RESULTS: In this study seven infants (6%) were born prematurely and four infants (3%) were classified as small for gestational age, while 11 (9%) of the infants weighed less than 2500 g. Low birth weight infants (LBW) were significantly more likely to require treatment in the neonatal intensive care unit (OR = 30.83, p = 0.00). Iron supplementation during pregnancy was associated with fewer underweight infants (OR = 3.92, p = 0.042). No associations were found between infant birth weight and maternal age, age at marriage, consanguinity, education level, current maternal employment, parity, pre-existing anaemia or anaemia in pregnancy, diabetes, folic acid intake, multivitamin intake or infant gender. Maternally-reported infant health issues, vaccination, medication, breast-feeding and infant nutrition, and use of secure car seats are also reported. CONCLUSIONS: The health of infants at birth in this UAE sample showed improvements compared to previous studies. The proportion of LBW infants is decreasing and continuing improvements in health care in the UAE are having a positive impact on infant health.

Characterisation of sucking dynamics of breastfeeding preterm infants: a cross sectional study.

BACKGROUND: Full breastfeeding is the ultimate aim for preterm infants to ensure they receive the full benefits of human milk however, preterm infants face a number of challenges associated with their immaturity and associated morbidities. In order to facilitate oral feeding, it is essential to have a sound knowledge of the sucking dynamics of the breastfed infant. The aim of this study was to measure and describe the sucking dynamics of the preterm breastfeeding infant. METHODS: A prospective cross sectional observational study was carried out at King Edward Memorial Hospital, Perth. 38 mothers and their preterm infants (birth gestation age: 23.6-33.3 weeks; corrected gestation age 32.7 to 39.9 weeks) were recruited. Intra-oral vacuum levels, tongue movement and milk intake for a single breastfeed was measured. Statistical analysis employed linear regression and linear mixed effects models. RESULTS: Synchronised ultrasound and intra-oral vacuum measurements show that the preterm infant generates vacuum by lowering their tongue in a parallel fashion, without distortion of the nipple/nipple shield. Baseline (B), mean (M) and (P) peak suck burst vacuums weakened over the course of a feed (B: p = 0.015; M: p = 0.018; P: p = 0.044) and mean and peak vacuums were weaker if the mother fed with a nipple shield (M: p = 0.012; P: p = 0.021). Infant milk intakes were higher when infants sucked for longer (p = 0.002), sucked for a greater proportion of the feed (p = 0.002), or had a greater sucking efficiency (p < 0.001). CONCLUSIONS: Breastfeeding preterm infants generated intra-oral vacuum in the same manner as term infants. Nipple shields were associated with weaker intra-oral vacuums. However, vacuum strengths were not associated with milk intake rather time spent actively sucking was related to milk volumes. Further research is required to elucidate factors that influence preterm infant milk intake during breastfeeding.

Milk ejection patterns remain consistent during the first and second lactations.

OBJECTIVE: Milk ejection is a critical physiological process for successful lactation in humans and without it little milk can be removed. Individual milk ejection patterns have been shown to remain consistent between breasts at different lactation stages and using different vacuum patterns with an electric breast pump. Little is known about the milk ejection characteristics during the second lactation period in the same mother. The objective of this study was to examine milk ejection characteristics in the same woman over two lactations. METHODS: One mother took part in two pumping studies during consecutive lactations. One pumping study examined milk ejection characteristics during simultaneous breast expression during the first lactation. The second pumping study (second lactation) used two different pumping patterns. Three distinct milk ejections were measured during each pumping session. RESULTS: Measurements of milk flow were used to compare the duration and time taken to reach the peak of each milk ejection for two pumping sessions from each of the lactations. There were no significant differences in milk ejection characteristics between breasts, using different pumping patterns, or between lactations in this mother (P > .05). CONCLUSION: Milk ejection appears to be a physiological response that is consistent across consecutive lactations within the same mother. This suggests that milk ejection characteristics are established during or prior to the first lactation. The infant appears to have little influence on the milk ejection characteristics of the mother.

Changes in milk composition associated with pethidine-PCEA usage after Caesarean section.

The effect of pethidine as patient-controlled epidural analgesia (PCEA) on specific biochemical components in breast milk in relation to the timing of secretory activation is not well investigated. The aim of this study was to compare biochemical timing of secretory activation between women who had a vaginal (V) or Caesarean birth with pethidine-PCEA (CBP). Several milk samples were collected daily from 36 mothers (17 V, 19 CBP) for the first 265 h post-partum. Protein and lactose concentrations and Na+ and K+ ion levels were measured. Samples were assigned to three time periods: 0-72, >72-165 and >165-265 h post-partum for statistical analyses. Data were analyzed using linear mixed effect models. In the first 72 h post-partum, the mean difference in lactose concentration was 5 gL-1 higher in group V (P < 0.05). From >72-165 h post-partum, protein and Na+ concentrations were lower in group V (P = 0.05, P = 0.02), and K+ levels were higher in group V (P < 0.001). From >165-265 h post-partum, there were no significant differences between the groups. Biochemically, secretory activation had occurred by 72 h post-partum in both groups. There were greater variations in measured biochemical components observed within group CBP initially. However, by 165 h post-partum, there were no differences in the biochemical components between the groups. This suggests that effects of pethidine-PCEA are diminished by 72 h post-partum and undetected by 165 h.

Breastmilk Production in the First 4 Weeks after Birth of Term Infants.

Breastmilk provides the ideal nutrition for the infant, and exclusive breastfeeding is recommended for the first 6 months. Adequate milk production by the mother is therefore critical, and early milk production has been shown to significantly affect milk production during established lactation. Previous studies indicate that milk production should reach the lower limit of normal for established lactation (440 mL per day) by day 11 after birth. We have used test-weighing of term infants before and after each breastfeed over 24 h to measure milk production in the first 4 weeks of lactation in mothers with and without perceived breastfeeding problems to provide information on how often milk production is inadequate. Between days 11 and 13, two-thirds of the mothers had a milk production of less than 440 mL per day, and between days 14 and 28, nearly one-third of the mothers had a milk production of less than 440 mL per day. The high frequency of inadequate milk production in early lactation and the consequence of suboptimal milk production in later lactation if left untreated suggest that objective measurement of milk production can identify mothers and infants at risk and support early intervention by a lactation specialist.

Infant Feeding Practices of Emirati Women in the Rapidly Developing City of Abu Dhabi, United Arab Emirates.

Rapid economic and cultural transition in the United Arab Emirates (UAE) has been accompanied by new challenges to public health; most notably a rapid rise in chronic disease. Breastfeeding is known to improve health outcomes in adulthood, is associated with reduced risk of developing chronic disease, and is therefore an important public health issue for this rapidly increasing population. Factors associated with infant feeding practices were examined in a cohort of 125 Emirati women and their infants, with data collected at birth and 3, 6 and 15 months postpartum by questionnaires and interviews. Participants were recruited in the Corniche Hospital, the main maternity hospital in the city of Abu Dhabi. Factors affecting the duration of breastfeeding and the introduction of complementary foods were investigated using univariate and multivariate statistics. Recommended infant feeding practices, such as exclusive breastfeeding for the first six months of life and timely introduction of appropriate complementary foods, were poorly adhered to. Factors implicated in early cessation of breastfeeding included: time to first breastfeed, mother's education level, employment status and early introduction of complementary foods.

Milk ejection patterns: an intra- individual comparison of breastfeeding and pumping.

BACKGROUND: Milk ejection is a transient episode critical to milk removal and women typically have multiple milk ejections during breastfeeding and pumping. Recently it was found that milk ejection characteristics such as number of milk ejections and periodicity were consistent throughout 12 months of lactation in women who expressed their milk with an electric breast pump. It is not known whether the stimulation of an infant at the breast influences milk ejection patterns or whether this is a programmed event. The aim of this study was to compare milk ejection patterns during breastfeeding and expressing milk with an electric pump within mothers. METHODS: Twelve lactating mothers with normal milk production (502-1356 mL) had milk ejection recorded by measuring the diameter of a major milk duct with ultrasound imaging throughout an entire breastfeed and a 15-min pumping session. Scans were analysed for timing, duration of duct dilation and maximum duct diameter. RESULTS: The initial milk ejection defined as the first increase in duct diameter was observed earlier during breastfeeding than during two phase pumping sessions but was not statistically significant (p = .057). There were no significant differences between the duration of the first or second milk ejection for mothers when breastfeeding or pumping at their maximum comfortable vacuum (p = .18; p = .99). The times taken to reach the peak duct diameter, or the first half of the milk ejection were also not found to be significantly different between breastfeeding and pumping. CONCLUSION: This study suggests that milk ejection patterns remain consistent within individual mothers regardless of whether the mother is breastfeeding or expressing milk indicating a likelihood of the process either being programmed or innate to the individual.

Asynchronous milk ejection in human lactating breast: case series.

BACKGROUND: Milk production is under the influence of autocrine control such that the rate of milk synthesis decreases as the breast fills with milk. Effective elimination of milk from the alveoli via the milk ejection reflex will therefore result in increased milk synthesis. It has been assumed that milk ejection occurs in all alveoli simultaneously; however, animal studies have indicated that full alveoli eject milk sooner than less full alveoli, suggesting heterogeneous emptying of the mammary gland. OBJECTIVE: The aim of this study was to determine whether milk ejection occurs asynchronously in the human lactating breast. METHODS: Retrospective analysis of videos made of ultrasound monitoring of milk ducts during pumping. Six video clips (4 women) of ultrasound monitored milk ejections showed obvious differences in the timing of milk flow between different main milk ducts. Duct diameter was simultaneously measured every second in 2 different ducts that drained 2 separate lobes of the breast. RESULTS: For 5 of 6 ultrasound duct monitoring sessions, both duct dilation and visualization of milk flow in the 2 separate main milk ducts differed by 2 to 8 seconds. For the remaining woman, milk was observed to eject from 1 part of the lobe, and when not removed, it flowed in a retrograde fashion into a different part of the lobe. CONCLUSION: Asynchrony of milk ejection occurs in the human lactating breast, suggesting that the timing of myoepithelial cell response differs, resulting in heterogeneous emptying of the gland.