Abstract
In this study, the 3D printability of a series of poly(3-hydroxybutyrate-
co
-3-hydroxyvalerate) (PHBV)/poly(lactic acid) (PLA) blends were investigated using fused filament fabrication ...(FFF). The studied blends suffered from poor 3D printability due to differences in compatibility and low thermal resistance. These shortcomings were addressed by incorporating a functionalized styrene-acrylate copolymer with oxirane moieties as a chain extender (CE). To enhance mechanical properties, the synergistic effect of 3D printing parameters such as printing temperature and speed, layer thickness and bed temperature were explored. Rheological analysis showed improvement in the 3D printability of PHBV:PLA:CE blend by allowing a higher printing temperature (220 °C) and sufficient printing speed (45 mm s
−1
). The surface morphology of fractured tensile specimens showed good bonding between layers when a bed temperature of 60 °C was used and a layer thickness of 0.25 mm was designed. The optimized printing samples shown higher storage modulus and strength, resulting in stiffer and stronger parts. The crystallinity, morphology and performance of the 3D printed products were correlated to share key methods to improve the 3D printability of PHBV:PLA based blends which may be implemented in other biopolymer blends, and further highlight how process parameters enhance the mechanical performance of 3D printed products.
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A graphite‐epoxy electrode (GE) modified with multiwalled carbon nanotubes (MWCNTs) and horseradish peroxidase (GE/MWCNTs‐HRP) was used to build a glyphosate biosensor whose performance in aqueous ...solutions depends on the enzyme activity. For the biosensor preparation, MWCNTs were deposited onto the GE surface by electrophoresis using an oxidative treatment (H2SO4/HNO3) in presence of cetyl tributylammonium bromide (CTAB) as a cationic surfactant. The surfactant was further removed from the MWCNTs surface by dipping the electrode in an EtOH/HCl solution. The physical immobilization of HRP and therefore the glyphosate sensing capabilities was tested at pH 4 where the herbicide exhibits one only species. Circular dichroism studies suggested that the secondary structure of HRP changes as a result of its interaction with glyphosate and that this change is intensified by the combination of glyphosate and H2O2, which may explain the decrease of the enzyme catalytic activity with the increase of glyphosate concentration. The glyphosate quantification in doped‐maize kernels was highly reproducible and exhibits detection and quantification limits of 1.32 pM and 1.63 pM respectively. The biosensor is also characterized by a high recovery (100 %) and precision (coefficient of variation <1 %) and can be employed in presence of interfering substances such as chlorpyrifos (an organophosphate pesticide) and starch.
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• In many perennial plants, seasonal flowering is primarily controlled by environmental conditions, but in certain polycarpic plants, environmental signals are locally gated by the presence of ...developing fruits initiated in the previous season through an unknown mechanism.
• Polycarpy is defined as the ability of plants to undergo several rounds of reproduction during their lifetime, alternating vegetative and reproductive meristems in the same individual.
• To understand how fruits regulate flowering in polycarpic plants, we focused on alternate bearing in Citrus trees that had been experimentally established as fully flowering or nonflowering.
• We found that the presence of the fruit causes epigenetic changes correlating with the induction of the CcMADS19 floral repressor, which prevents the activation of the floral promoter CiFT2 even in the presence of the floral inductive signals. By contrast, newly emerging shoots display an opposite epigenetic scenario associated with CcMADS19 repression, thereby allowing the activation of CiFT2 the following cold season.
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Gestational diabetes mellitus (GDM) prevalence is increasing and becoming a major public health concern. Whether a Mediterranean diet can help prevent GDM in unselected pregnant women has yet to be ...studied.
We conducted a prospective, randomized controlled trial to evaluate the incidence of GDM with two different dietary models. All consecutive normoglycemic (<92 mg/dL) pregnant women at 8-12 gestational weeks (GW) were assigned to Intervention Group (IG, n = 500): MedDiet supplemented with extra virgin olive oil (EVOO) and pistachios; or Control Group (CG, n = 500): standard diet with limited fat intake. Primary outcome was to assess the effect of the intervention on GDM incidence at 24-28 GW. Gestational weight gain (GWG), pregnancy-induced hypertension, caesarean section (CS), preterm delivery, perineal trauma, small and large for gestational age (SGA and LGA) and admissions to neonatal intensive care unit were also assessed. Analysis was by intention-to-treat.
A total of 874 women completed the study (440/434, CG/IG). According to nutritional questionnaires and biomarker analysis, women in the IG had a good adherence to the intervention. 177/874 women were diagnosed with GDM, 103/440 (23.4%) in CG and 74/434(17.1%) in IG, p = 0.012. The crude relative risk (RR) for GDM was 0.73 (95% CI: 0.56-0.95; p = 0.020) IG vs CG and persisted after adjusted multivariable analysis, 0.75(95% CI: 0.57-0.98; p = 0.039). IG had also significantly reduced rates of insulin-treated GDM, prematurity, GWG at 24-28 and 36-38 GW, emergency CS, perineal trauma, and SGA and LGA newborns (all p<0.05).
An early nutritional intervention with a supplemented MedDiet reduces the incidence of GDM and improves several maternal and neonatal outcomes.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We demonstrate optical fiber sensors based on highly coupled multicore fibers operating with the optical Vernier effect. The sensors are constructed using a simple device incorporating single-mode ...fibers (SMFs) and a segment of a multicore fiber. In particular, we evaluated the performance of a sensor based on a seven-core fiber (SCF) spliced at both ends to conventional SMFs, yielding a versatile arrangement for realizing Vernier-based fiber sensors. The SMF-SCF-SMF device can be fabricated using standard splicing procedures and serve as a "building block" for both, reflection and transmission sensing configurations. As demonstrated with our experimental results, the Vernier arrangements can yield a ten-fold increase in sensitivity for temperature measurements compared to a conventional single SMF-SCF-SMF device, thereby confirming the enhanced sensitivity that can be attained with this optical effect. Furthermore, through theoretical analysis, we obtain the relevant parameters that must be optimized in order to achieve an optimal sensitivity for a specific application. Our findings thus provide the necessary guidelines for constructing Vernier-based sensors with all-fiber devices based on highly coupled multicore optical fibers, which constitutes an ideal framework to develop highly sensitive fiber sensors for different applications.
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Absolute configuration assignment of stigmasterol oxiranes Fuentes‐Figueroa, Miguel Á.; Joseph‐Nathan, Pedro; Burgueño‐Tapia, Eleuterio
Chirality (New York, N.Y.),
February 2022, 2022-02-00, 20220201, Volume:
34, Issue:
2
Journal Article
Peer reviewed
Diastereoisomeric stigmasterol oxiranes 4, 5, 8, and 9 are known phytosterol oxidation products (POPs) that have been evaluated for their cytotoxicity, although the results are of limited ...significance since, in most cases, they were evaluated as mixtures. Consequently, to establish biological activity hierarchy of these oxides, it is critical to evaluate individual pure POPs. Therefore, we now describe the obtention of individual molecules and their absolute configuration (AC) determination. The two acetylated C‐5−C‐6 oxiranes 6 and 7; the two acetylated C‐22−C‐23 oxides 10 and 11, obtained by means of Δ5 double bond protection‐deprotection; and the four C‐5−C‐6, C‐22−C‐23 diepoxystigmasteryl acetates 19–22 were now individually gained and their AC determined by vibrational circular dichroism. Vibrational modes associated with the C‐5−C‐6 and the C‐22−C‐23 bonds were identified in dioxiranes 19–22 and used to assign the AC of monoepoxides 6, 7, 10, and 11. The AC of biological active non‐acetylated molecules follows immediately. Due to the scarce spectroscopic information available for these POPs, the 1H and 13C NMR chemical shifts of 3–22 were assigned using 1D‐ and 2D‐NMR experiments.
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In this paper, a ratiometric approach to sensing temperature variations is shown using specialty fiber optic devices. We analyzed the transmission response of cascaded segments of multicore fibers ...(MCFs), and dissimilar lengths were found to generate an adequate scheme for ratiometric operation. The perturbation of optical parameters in the MCFs translates to a rich spectral behavior in which some peaks increase their intensity while others decrease their intensity. Thus, by selecting opposite-behavior peaks, highly sensitive ratiometric measurements that provide robustness against spurious fluctuations can be performed. We implemented this approach using seven-core fiber (SCF) segments of 5.8 cm and 9.9 cm. To test the system's response under controlled perturbations, we heated one of the segments from ambient temperature up to 150 °C. We observed defined peaks with opposite behavior as a function of temperature. Two pairs of peaks within the interrogation window were selected to perform ratiometric calculations. Ratiometric measurements exhibited sensitivities 6-14 times higher than single-wavelength measurements. A similar trend with enhanced sensitivity in both peak pairs was obtained. In contrast to conventional interferometric schemes, the proposed approach does not require expensive facilities or micrometric-resolution equipment. Moreover, our approach has the potential to be realized using commercial splicers, detectors, and filters.
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We propose an experimental setup to measure the refractive index (RI) of two independent liquid samples by analyzing a single optical signal. We spliced a section of a seven-core fiber (SCF) into ...each arm of a 1 × 2 fiber coupler and spliced additional single mode fiber (SMF) to use as fiber probe tips. As the spatial frequency of the characteristic sinusoidal response of an SCF is a function of the fiber length, we used two different lengths (3 and 10 cm) in our realization. A superluminescent diode (SLD) is used as the light source, and the reflected light by both fiber tips is acquired through an optical circulator. An optical spectrum analyzer (OSA) is used to analyze the spectral response of the combined signals from both fiber tips. We characterized this sensing system by immersing the fiber tips in liquid samples with a RI between 1.3175 and 1.4040. We show that the two independent RI measurements can be retrieved by performing a Fourier transform on the recorded optical spectrum. In particular, we demonstrate that with adequate calibration, the Fresnel coefficients can be calculated independently. The presented approach represents a straightforward and cost-effective fiber implementation for multipoint sensing.
The diagnosis of respiratory viruses of zoonotic origin (RVsZO) such as influenza and coronaviruses in humans is crucial, because their spread and pandemic threat are the highest. Surface-enhanced ...Raman spectroscopy (SERS) is an analytical technique with promising impact for the point-of-care diagnosis of viruses. It has been applied to a variety of influenza A virus subtypes, such as the H1N1 and the novel coronavirus SARS-CoV-2. In this work, a review of the strategies used for the detection of RVsZO by SERS is presented. In addition, relevant information about the SERS technique, anthropozoonosis, and RVsZO is provided for a better understanding of the theme. The direct identification is based on trapping the viruses within the interstices of plasmonic nanoparticles and recording the SERS signal from gene fragments or membrane proteins. Quantitative mono- and multiplexed assays have been achieved following an indirect format through a SERS-based sandwich immunoassay. Based on this review, the development of multiplex assays that incorporate the detection of RVsZO together with their specific biomarkers and/or secondary disease biomarkers resulting from the infection progress would be desirable. These configurations could be used as a double confirmation or to evaluate the health condition of the patient.
Summary
In Citrus, the response to environmental floral inductive signals is inhibited by the presence of developing fruits. The mechanism involves epigenetic activation of the CcMADS19 locus (FLC ...orthologue), encoding a floral repressor.
To understand how this epigenetic regulation is reverted to allow flowering in the following season, we have forced precocious sprouting of axillary buds in fruit‐bearing shoots, and examined the competence to floral inductive signals of old and new leaves derived from them.
We have found that CcMADS19 is enriched in repressive H3K27me3 marks in young, but not old leaves, revealing that axillary buds retain a silenced version of the floral repressor that is mitotically transmitted to the newly emerging leaves, which are able to induce flowering.
Therefore, we propose that flowering in Citrus is necessarily preceded by vegetative sprouting, so that the competence to respond to floral inductive signals is reset in the new leaves.
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