Mid-infrared Transmission Spectroscopy Research Articles

Exclusive or partial breastfeeding and estimated protein intake in infancy: Associations with childhood growth and body composition at 7 years of age in the Odense Child Cohort.

Protein intake in infancy influences infant growth, body composition, and possibly metabolic programming later in life. Our objectives were to investigate whether macronutrient content in mother's own milk (MOM) differed between exclusive (EBF) or partial breastfeeding (PBF), including an estimation of protein intake (ePI) during the first 6 months of life. Second, to investigate associations of feeding type and ePI with childhood growth and body composition at 7 years. In a subset of 150 participants from the Odense Child Cohort, MOM was analysed for macronutrient content using midinfrared transmission spectroscopy. Information on breastfeeding duration was collected through weekly SMS questionnaires and used to calculate ePI. Outcomes were weight-for-age z-scores (WAZ) and height-for-age z-scores (HAZ) from birth to 7 years, and body composition in terms of dual X-ray absorptiometry fat mass, fat-free mass and calculated indexes at 7 years. The macronutrient content in MOM did not differ between EBF and PBF, but ePI was significantly higher in PBF infants than in EBF infants at 6 months. We found no difference in WAZ or HAZ until 7 years of age according to feeding type, but within the PBF group, ePI was positively associated with 7-year WAZ (β = 0.001; 95% CI 0.000-0.003; p = 0.03) and HAZ (β = 0.002; 0.001-0.003;p = 0.007). ePI was not associated with body composition at 7 years. Milk macronutrient content and childhood growth did not differ between EBF and PBF during infancy. Estimated protein intake in partially breastfed infants was positively associated with childhood growth, but not body composition, at 7 years of age.

Breast size in lactating women and the content of macronutrients in human milk.

Although the primary function of a woman's breast is milk synthesis, only a few studies have evaluated the relationship between breast size and human milk composition, showing equivocal results. This study aims to test if breast size during fully established lactation is related to energy density and content of macronutrients in human milk. Mothers of healthy, born-on-term infants at stage III of lactogenesis (N = 137) provided breast milk samples. Milk composition was analyzed using midinfrared transmission spectroscopy. The breast size index was calculated by dividing the breast by the circumference below the breast. Stepwise forward linear regression showed a negative association between breast size index and lactose concentration in breast milk (β = -.242, p = .003). The final model, which includes breast size index, feeding frequency, and maternal energy intake together explained around 13% of the variance in breast milk lactose content (R2 adj = .126, p < .001). No statistically significant relationship was found between breast size index and milk's energy density, protein, and fat content. This is the first study that shows a negative relationship between breast size during fully established lactation and lactose concentration in milk in a large sample size. No relationship between other macronutrients and breast size indicates that large breast size is not necessary for adequate milk production; however, it may contribute to an altered lactose concentration.

Maternal Diet Influences Human Milk Protein Concentration and Adipose Tissue Marker.

(1) Background: Adequate protein intake plays an essential role in growth and neurodevelopment, especially in preterm infants. We investigated the effects of maternal diet and body mass index (BMI) on human milk (HM) composition. (2) Methods: HM samples were obtained from 136 lactating mothers (BMI: 18.0−36.7 kg/m2), of which 93% gave birth to preterm infants. Macronutrient content in HM was measured by mid-infrared transmission spectroscopy. Leptin and adiponectin were analyzed using appropriate ELISAs. Maternal diet was determined by 24-h recall. (3) Results: Significant positive associations were found between protein, fat, carbohydrate and energy intake, and levels of corresponding macronutrients in HM, especially in protein concentrations (p < 0.001). An increased protein intake was positively correlated with adiponectin (p < 0.001) and leptin (p = 0.035) in HM. Maternal BMI was positively associated with a higher protein level in HM (p < 0.05), as well as with a higher dietary protein intake (p < 0.05). (4) Conclusions: Knowledge of maternal diet and BMI impacting HM composition is essential to optimize the feeding of newborn infants. This is especially relevant in the nutritional management of preterm infants; it can be utilized in approaches to improve growth rates and the appropriate development of infants and to prevent obesity.

Human Milk Processing and Its Effect on Protein and Leptin Concentrations.

(1) Background: For the storage of human milk (HM), freezing, thawing, and/or pasteurization are routinely used in neonatal intensive care units. We aimed to analyze the effects of different HM processing types on the nutritional contents in HM, adipose tissue, and the neuroprotection markers leptin and adiponectin. (2) Methods: HM samples from 136 mothers of preterm and term infants (gestational age 23 + 0 to 41 + 6) were collected and divided into four groups: (i) fresh HM, (ii) fresh pasteurized HM, (iii) thawed HM, and (iv) thawed pasteurized HM. The macronutrients were analyzed by mid-infrared transmission spectroscopy and the adiponectin and leptin were analyzed by high-sensitivity adiponectin and leptin enzyme-linked immunosorbent assay (ELISA). (3) Results: No significant differences were observed in the protein, carbohydrate, or fat concentrations between the HM processing types. The leptin levels were significantly lower after pasteurization in comparison to HM without pasteurization (p &lt; 0.001). The protein levels in extremely preterm HM were significantly lower compared to those in moderate/late preterm HM and term HM (p &lt; 0.05). (4) Conclusions: HM processing had an impact on leptin concentrations but no effect on the protein level. These data support the use of unpasteurized human milk for preterm infants' nutrition and normal brain development. The protein levels of the milk of mothers from preterm compared to full-term infants differed, underlining the importance of individualized target fortification.

Consumption of Animal Source Foods Is Associated With Differences in Breastmilk Energy and Macronutrient Composition in Rural Bangladesh

ObjectivesTo quantify associations of maternal consumption of animal source foods during lactation with maternal milk (MM) energy and macronutrient composition in a population with a high burden of childhood stunting.MethodsWe studied 99 mother-infant dyads from the Projahnmo pregnancy cohort in Sylhet, Bangladesh. Data on maternal diet was collected using a food frequency questionnaire administered at 1-month postpartum. Mothers reported how many times (never to daily) a food item was consumed in the past 7 days. We assessed intakes of red meat, liver, poultry, fish, eggs, and milk and milk products (sum of milk, yoghurt, milk powder, and khoa). Mothers collected their milk mid-feed at 1-month postpartum. True protein, fat, and total carbohydrate content of MM were determined using mid-infrared transmission spectroscopy (MIRIS AB, Uppsala, Sweden). Total energy was calculated using the Atwater general calorie conversion factor. To quantify associations of animal source food consumption with MM composition, we used linear regression analysis, adjusting for maternal body mass index, household wealth quintile, and days postpartum.ResultsMedian maternal age was 24 years. 31% of mothers were underweight and 15% were overweight/obese at enrollment. MM samples were collected at a median of 50 days postpartum. The median MM energy content was 22.9 kcal/oz. Median fat content was 4.7 g/dL, carbohydrate 7.8 g/dL, and protein 0.9 g/dL. In adjusted analyses, each serving/week of milk and milk products was associated with increased MM energy (β 0.33 kcal/oz; 95% CI 0.06, 0.60) and fat (β 0.13 g/dL; 95% CI 0.03, 0.23). Each serving/week of liver was associated with decreased carbohydrate (β −0.06 g/dL; 95% CI −0.11, −0.01) and increased protein (β 0.06 g/dL; 95% CI 0.02, 0.10) content. Each serving/week of red meat was associated with increased protein content (β 0.06 g/dL; 95% CI 0.01, 0.12). Intake of total animal source foods, poultry, fish, and eggs was not associated with MM composition.ConclusionsIntakes of some animal source foods were associated with MM composition at 1-month postpartum in rural Bangladesh. Increasing consumption of certain animal source foods during lactation could be an effective strategy to optimize MM composition, which may benefit infant growth outcomes in low-to-middle-income countries.Funding SourcesNICHD, Brigham Research Institute.

Rydberg excitons in synthetic cuprous oxide Cu2O

High-lying Rydberg states of Mott-Wannier excitons are receiving considerable interest due to the possibility of adding long-range interactions to the physics of exciton-polaritons. Here, we study Rydberg excitation in bulk synthetic cuprous oxide grown by the optical float zone technique and compare the result with natural samples. X-ray characterization confirms both materials are mostly single crystal, and mid-infrared transmission spectroscopy revealed little difference between synthetic and natural material. The synthetic samples show principal quantum numbers up to $n=10$, exhibit additional absorption lines, plus enhanced spatial broadening and spatial inhomogeneity. Room temperature and cryogenic photoluminescence measurements reveal a significant excess of copper vacancies in the synthetic material. These measurements provide a route towards achieving \mbox{high-$n$} excitons in synthetic crystals, opening a route to scalable quantum devices.

Nonlinear interferometer for Fourier-transform mid-infrared gas spectroscopy using near-infrared detection.

Nonlinear interferometers allow for mid-infrared spectroscopy with near-infrared detection using correlated photons. Previous implementations have demonstrated a spectral resolution limited by spectrally selective detection. In our work, we demonstrate mid-infrared transmission spectroscopy in a nonlinear interferometer using single-pixel near-infrared detection and Fourier-transform analysis. A sub-wavenumber spectral resolution allows for rotational-line-resolving spectroscopy of gaseous samples in a spectral bandwidth of over 700 cm-1. We use methane transmission spectra around 3.3 μm wavelength to characterize the spectral resolution, noise limitations and transmission accuracy of our device. The combination of nonlinear interferometry and Fourier-transform analysis paves the way towards performant and efficient mid-infrared spectroscopy with near-infrared detection.

Probing the ultrafast electron and lattice dynamics of gold using femtosecond mid-infrared pulses

We study the ultrafast electron and lattice dynamics of thin gold films with mid-infrared transmission and reflection pump-probe spectroscopy. We determine the time dependence of the dielectric function, which yields the electron-phonon coupling constant G that determines the energy exchange rate between the electrons and the lattice. From the experimentally obtained dielectric function, we determine the dependence of the electron-electron and the electron-lattice scattering rates on the electron and the lattice temperature.

Use of near and mid infra-red spectroscopy for analysis of protein, fat, lactose and total solids in raw cow and camel milk

Milk samples (150 cow and 217 camel milk samples) were analyzed for protein, fat, lactose and total solids by near and mid-infrared transmission spectroscopy. Excellent positive correlations between the two methods were obtained for both types of milk (p < 0.001); for protein (r ≥ 0.96), fat (r ≥ 0.99), lactose (r = 0.82) and total solids (r = 0.90). The mean of the relative difference ((MIR values – NIR values)/0.5 (MIR values + NIR values) × 100%) for cow and camel milk were, for protein (+8.2 & +13.4%), fat (−9.3 & +0.9%), lactose (−5.4 &−0.7%) and total solids (−2.2 &−3.4%), respectively. The difference between the two methods may be due to the effects of differences in milk homogeneity, especially with respect to casein micelles and fat globules.

Maternal body mass index, parity and smoking are associated with human milk macronutrient content after preterm delivery

BackgroundMaternal characteristics may be associated with human milk macronutrients but no definite conclusions have been made to date. AimThis study aimed to determine the relationship of maternal-associated factors on the content of macronutrients in human milk for the first six weeks after preterm delivery. Study designProspective observational cohort study. SubjectsMilk samples were collected from mothers after premature birth between 24 + 0–35 + 6 weeks. Outcome measuresMacronutrients and energy content were analyzed by mid-infrared transmission spectroscopy. Demographic and anthropometric data from mothers were systematically recorded. ResultsA total 1.558 human milk samples from 192 mothers were analyzed.Colostrum: higher protein (p = 0.001) and lower carbohydrate content (p = 0.003) were present in primiparous compared to multiparous milk. Vaginal birth was associated with increased carbohydrate content (p = 0.021). Fat and energy content in colostrum was not related to any maternal characteristics.Mature human milk: similarly to colostrum, higher protein content (p = 0.001) and lower carbohydrates content (p = 0.022) were observed in primiparous compared to multiparous milk. The mode of delivery was found to be another factor possibly influencing protein and carbohydrate levels (p = 0.036, p = 0.003, respectively). Pre-pregnancy obesity was associated with increased fat (p = 0.030) and energy content (p = 0.020) in human milk. On the contrary, smoking had a negative relationship to fat and energy content (p = 0.026, p = 0.007, respectively). ConclusionHuman milk macronutrient concentration after preterm delivery is associated with pre-pregnancy obesity, parity, mode of delivery and smoking. The impact of maternal factors on human milk composition should be taken into account in a strategy of feeding in premature infants.

Mid-IR band strength, density, refractive index, and thermal evolution study for solid CH2DOH pure and in astrophysical relevant mixtures.

We present a novel experimental study on solid CH2DOH pure and in astrophysical relevant mixtures. Solid samples were accreted under ultra high vacuum conditions at 17 K and were analyzed by mid-infrared transmission spectroscopy. Refractive index, density, and mid-IR band strength values were measured for pure solid CH2DOH. The refractive index was also measured for CH2DOH:H2O, CH2DOH:CO, and CH2DOH:CH3OH mixtures. For all samples, the thermal evolution of the main band profile was studied. We used the interference laser technique (HeNe laser, λ = 543.5 nm) to measure the samples thickness and a numerical method to measure the refractive index starting from the amplitude of the interference curve. We obtained the ice density through the Lorentz-Lorenz relation. To calculate the band strength values we used the linear fit of the integrated band intensities with respect to the column densities. Samples deposited at 17 K were warmed up to their sublimation temperature. Spectra were taken at selected temperatures to study their thermal evolution. The results are discussed in view of their relevance for the interpretation of astronomical IR spectra.

Biochemical Variations of Breast Milk Composition Compared with Substitution Formula in Feeding of Preterm of Mothers With or Without Pathologic Pregnancies

Breast milk is the main source of energy and nutrients for preterm and term newborns. The aim of the study was to determine the biochemical differences between breast milk and substitution formula used in feeding of preterm newborns and differences in composition of breast milk according to mothers demographic and pregnancy parameters. A group of 54 mothers with pathologic pregnancies of preterm gestational age between 27-37 weeks was studied to determine the biochemical composition of breast milk in the first 7 days of lactation and then to compare it with milk formula substitution. Most of them (42%) had a diagnosis of chronic hypertension, followed by chronic renal diseases (29%). Several parameters like gestational age, maternal age, lactation day when sampling milk, type of birth (natural / C-section), origin of mother (rural / urban), gender of the child were analyzed. The biochemical analysis of macronutrients (carbohydrates, lipids, proteins) and energetic value of the collected breast milk was performed by using an indirect method, infrared spectroscopy (mid-infrared transmission spectroscopy) by means of an automatic device. Gestational age, mother�s age and day of lactation (during the first week post-partum) did not produce a statistically significant difference in the composition of breast milk. There were no statistically significant changes with the type of delivery (cesarean versus natural) and gender of the preterm newborn. Higher lipid, carbohydrates and protein concentration was observed in milk substitution formula than in breast milk. Energetic values of analyzed milk substitution formula showed a statistically significant difference (p [0.05) when compared with breast milk.

Beyond Fourier Transform Infrared Spectroscopy: External Cavity Quantum Cascade Laser-Based Mid-infrared Transmission Spectroscopy of Proteins in the Amide I and Amide II Region.

In this work, we present a setup for mid-IR measurements of the protein amide I and amide II bands in aqueous solution. Employing a latest generation external cavity-quantum cascade laser (EC-QCL) at room temperature in pulsed operation mode allowed implementing a high optical path length of 31 μm that ensures robust sample handling. By application of a data processing routine, which removes occasionally deviating EC-QCL scans, the noise level could be lowered by a factor of 4. The thereby accomplished signal-to-noise ratio is better by a factor of approximately 2 compared to research-grade Fourier transform infrared (FT-IR) spectrometers at equal acquisition times. Employing this setup, characteristic spectral features of three representative proteins with different secondary structures could be measured at concentrations as low as 1 mg mL-1. Mathematical evaluation of the spectral overlap confirms excellent agreement of the quantum cascade laser infrared spectroscropy (QCL-IR) transmission measurements with protein spectra acquired by FT-IR spectroscopy. The presented setup combines performance surpassing FT-IR spectroscopy with large applicable optical paths and coverage of the relevant spectral range for protein analysis. This holds high potential for future EC-QCL-based protein studies, including the investigation of dynamic secondary structure changes and chemometrics-based protein quantification in complex matrices.

Is targeted fortification of human breast milk an optimal nutrition strategy for preterm infants? An interventional study.

BackgroundFortifying human milk contributes to the prevention of postnatal growth failure in preterm infants. Because of the natural variability of human milk, targeted fortification of human milk has been advocated. However, data regarding the efficacy and safety of prolonged targeted fortification are scarce. We aimed to assess the safety of targeted fortification of human milk in preterm infants compared with standard fortification, as well as the effects on infant growth.MethodsWe conducted an interventional study during hospital stay in healthy very low birth weight preterm infants who were exclusively fed human milk. Pools of human milk collected for 24 h were analysed using mid-infrared transmission spectroscopy. Targeted fortification of human milk was performed by adding macronutrients to native human milk to obtain optimal ratios of fat (4.4 g), carbohydrates (8.8 g), and protein (3 g) per 100 ml. The intervention period lasted 4–7 weeks. Weekly weight and daily growth rates were compared with those of a standardized fortification group of very low birth weight preterm infants who received standard fortified human milk (n = 10). The osmolality as well as the metabolic and gastrointestinal tolerance were monitored. Intergroup differences were evaluated using the Mann–Whitney U-test.ResultsA total of 10 preterm infants (birth weight 1223 ± 195 g; gestational age 29.1 ± 1.03 weeks) were enrolled and 118 samples of pooled milk were analysed. On average, 1.4 ± 0.1 g of protein, 2.3 ± 0.5 g of carbohydrate, and 0.3 ± 0.1 g of fat per 100 ml were added to the milk. Osmolality values after target fortification were within recommended limits (376 ± 66 mOsml/kg). Weekly weight gain (205.5 g; 95 % CI 177–233 vs 155 g; 95 % CI 132–178; p = 0.025) and daily growth rates (15.7 g/kg/day; 95 % CI 14.5–16.9 vs 12.3 g/kg/day; 95 % CI 10.7–13.9; p = 0.005) were higher in infants receiving target fortification than in infants receiving standardized fortification. The infants receiving targeted fortified milk consumed similar volumes as infants in the standardized fortification group (148 ± 4.5 vs 146 ± 4 ml/kg/day). No signs of either gastrointestinal or metabolic intolerance were observed.ConclusionsTarget fortification appears to promote growth in very low birth weight preterm infants without any detrimental effects.Trial registration NCT02716337

Mid-infrared transmission imaging and spectroscopy with PbSnTe laser diodes grown with stoichiometry-controlled liquid-phase epitaxy

Bi- or In-doped n-PbTe/p-PbSnTe/Tl-doped p-PbTe double-hetero (DH) diode structures were fabricated using the temperature difference method under controlled vapour pressure (TDM-CVP) liquid-phase epitaxy (LPE). We fabricated a PbSnTe/PbTe DH-junction laser diode (LD) using TDM-CVP LPE and subsequently obtained sharp lasing spectra between 7.2 (1390cm−1) and 9.4μm (1070cm−1) by varying the ambient temperature of the diode. When the fabricated Pb0.89Sn0.11Te/PbTe LD was used to image Si wafers with different resistivities, we obtained a clear contrast between the wafers. We also obtained the mid-infrared imaging spectrum of benzoic acid (BA) using the fabricated Pb0.89Sn0.11Te/PbTe LD, and the absorbance image obtained using the fabricated LD showed good agreement with a Fourier transform infrared (FTIR) spectrum. We observed sharp lasing spectra between 7.20 (1390cm−1) and 7.80μm (1280cm−1) by varying the ambient temperature of the diode sample. We observed some absorption peaks in the obtained infrared absorption spectra of para-nitrobenzoic acid (PNBA) and BA; a peak at approximately 7.45μm (1345cm−1) in the spectrum of PNBA originated from NO2 symmetric stretching bands. Moreover, we observed that the other peaks in these spectra also match peaks from conventional FTIR spectra.

Doped semiconductors with band-edge plasma frequencies

In this work, the authors demonstrate the potential of epitaxially grown highly doped InSb as an engineered, wavelength-flexible mid-IR plasmonic material. The authors achieve doping concentrations over an order of magnitude larger than previously published results and show that such materials have plasma frequencies corresponding to energies larger than the material's band-gap. These semiconductor-based plasmonic metals open the door to homoepitaxial integration of plasmonic or epsilon-near-zero materials with optoelectronic devices at mid-infrared wavelengths. The materials are characterized by Hall measurements, mid-infrared transmission and reflection spectroscopy, and near-infrared transmission spectroscopy. The opportunities offered and the limitations presented by this material system are discussed and analyzed.

In vitro measurements of physiological glucose concentrations in biological fluids using mid-infrared light

Mid-infrared transmission spectroscopy using broadband mid-infrared or Quantum Cascade laser sources is used to predict glucose concentrations of aqueous and serum solutions containing physiologically relevant amounts of glucose (50-400 mg/dL). We employ partial least squares regression to generate a calibration model using a subset of the spectra taken and to predict concentrations from new spectra. Clinically accurate measurements with respect to a Clarke error grid were made for concentrations as low as 30 mg/dL, regardless of background solvent. These results are an important and encouraging step in the work towards developing a noninvasive in vivo glucose sensor in the mid-infrared.

Estimating volatile fatty acid concentrations in rumen samples by Fourier transform mid-IR transmission spectroscopy

This paper investigates the possibility of determining concentrations of acetate, propionate and butyrate in rumen fluid by Fourier transform mid-infrared (FTIR) transmission spectroscopy. A total of 308 samples were used for calibration of the FTIR instrument, normally used for milk analysis. The samples consisted of semi-artificial rumen fluids, spiked with acetate, propionate and butyrate with and without added bicarbonate and phosphate. The Test set consisted of 123 rumen in vitro samples with a mean value for the sum of the three volatile fatty acids of 5.5 g/L (84 mM), determined by high-performance liquid chromatography (HPLC). Stepwise regression was applied to find suitable wavelengths for predictions, mainly in the region of 6.3–10 μm. A total of 12–13 wavelengths were used for the prediction equations and resulted in mean prediction errors (MPE) ranging from 0.031 to 0.043 g/L (approximately 0.5 mM) for the three VFAs and ratios of population standard deviation (SD) to SD of the regressions > 11.6. The calibration equation predicted the Test set well, with a MPE of 0.074, 0.066 and 0.119 for acetate, propionate and butyrate, respectively. More than 0.5 of the mean square prediction error was due to non-random errors which it should be possible to adjust for by use of calibration samples. A rough estimate also indicated that 0.09–0.16 of the mean square prediction error was due the HPLC method. The FTIR method is recommended for applications were required measurement accuracies are in the range of 1 mM.

Fingerprints of spatial charge transfer in quantum cascade lasers

We show that mid-infrared transmission spectroscopy of a quantum cascade laser provides clear-cut information on changes in charge location at different bias. Theoretical simulations of the evolution of the gain/absorption spectrum for a λ∼7.4 μm InGaAs/AlInAs/InP quantum cascade laser have been compared with the experimental findings. Transfer of electrons between the ground states in the active region and the states in the injector goes hand in hand with a decrease of discrete intersubband absorption peaks and an increase of broad, high-energy absorption toward the continuum delocalized states above the barriers.

Comparative Study of Wine Tannin Classification Using Fourier Transform Mid-Infrared Spectrometry and Sensory Analysis

Wine tannins are fundamental to the determination of wine quality. However, the chemical and sensorial analysis of these compounds is not straightforward and a simple and rapid technique is necessary. We analyzed the mid-infrared spectra of white, red, and model wines spiked with known amounts of skin or seed tannins, collected using Fourier transform mid-infrared (FT-MIR) transmission spectroscopy (400-4000 cm(-1)). The spectral data were classified according to their tannin source, skin or seed, and tannin concentration by means of discriminant analysis (DA) and soft independent modeling of class analogy (SIMCA) to obtain a probabilistic classification. Wines were also classified sensorially by a trained panel and compared with FT-MIR. SIMCA models gave the most accurate classification (over 97%) and prediction (over 60%) among the wine samples. The prediction was increased (over 73%) using the leave-one-out cross-validation technique. Sensory classification of the wines was less accurate than that obtained with FT-MIR and SIMCA. Overall, these results show the potential of FT-MIR spectroscopy, in combination with adequate statistical tools, to discriminate wines with different tannin levels.