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Advanced Monte Carlo for Acquisition Sampling in Bayesian Optimization
Get PDFOptimizing complex systems usually involves costly and time-consuming experiments, where selecting the experiments to perform is fundamental. Bayesian optimization (BO) has proved to be a suitable optimization method in these situations thanks to its sample efficiency and principled way of learning from previous data, but it typically requires that experiments are sequentially performed. Fully distributed BO addresses the need for efficient parallel and asynchronous active search, especially where traditional centralized BO faces limitations concerning privacy in federated learning and resource utilization in high-performance computing settings. Boltzmann sampling is an embarrassingly parallel method that enables fully distributed BO using Monte Carlo sampling. However, it also requires sampling from a continuous acquisition function, which can be challenging even for advanced Monte Carlo methods due to its highly multimodal nature, constrained search space, and possibly numerically unstable values. We introduce a simplified version of Boltzmann sampling, and we analyze multiple Markov chain Monte Carlo (MCMC) methods with a numerically improved log EI implementation for acquisition sampling. Our experiments suggest that by introducing gradient information during MCMC sampling, methods such as the MALA or CyclicalSGLD improve acquisition sampling efficiency. Interestingly, a mixture of proposals for the Metropolis–Hastings approach proves to be effective despite its simplicity
Effect of Shell Thickness on the Oxygen Evolution Activity of Core@shell Fe3O4@CoFe2O4 Nanoparticles
No full textHydrogen production via water splitting requires efficient electrocatalysts to reduce the overpotential of the anodic oxygen evolution reaction (OER) and cathodic hydrogen evolution reaction (HER). In this study, we investigated the influence of apparent shell thickness on the electrocatalytic activity of Fe3O4@CoFe2O4 core@shell nanoparticles, an efficient noble metal-free OER catalyst in alkaline media. Three different types of core@shell nanoparticles were synthesized by the seed-mediated crystal growth of cobalt ferrite on pristine magnetite nanoparticles. The synthesis conditions were adapted to modulate the shell structure. Importantly, all proposed core@shell structures showed excellent stability during electrochemical testing, which is important for eventual industrial applications. We showed that the electrocatalytic performance of Fe3O4@CoFe2O4 core@shell nanoparticles was significantly influenced by the shell structure. The cooperative redox mechanism proposed to be the origin of the activity enhancement in core@shell nanoparticles was investigated by using in situ soft X-ray absorption spectroscopy (XAS). XAS revealed that cooperative redox interactions occurred between Co(II) and Fe(II) residing in close proximity at the core/shell interface, hence requiring a thin and continuous CoFe2O4 shell. Overall, this study provides insights into the design of efficient core@shell nanocatalysts for the OER, offering a path toward improving the performance of earth-abundant transition metal-oxide (TMO) catalysts for sustainable H2 production
o-Halogenation and -Alkoxylation of Phenylglycine Derivatives by Pd-Mediated C-H Functionalization: Scope and Limitations
Get PDFOrthopalladated derivatives from substituted phenylglycines [Pd(μ-Cl)(C6H3R1C(R2)(R3)N(R4)2]2 (1) react with halogenating reagents (PhICl2, Br2, I2) (2) to give the corresponding o-halogenated amino acids C6H3(X)R1C(R2)(R3)N(R4)2 (3). The reaction is general and tolerates a variety of functional groups (R1 to R4) at the aryl ring, the Cα, and the N atom. On the other hand, the reaction of [Pd(μ-Cl)(C6H3R1C(R2)(R3)N(R4)2]2 (1) with PhI(OAc)2 in the presence of a variety of alcohols R5OH (4) gives the o-alkoxylated phenylglycines C6H3(OR5)R1C(R2)(R3)N(R4)2 (5), also as a general process. A partial loss of the enantiomeric excess is observed when the starting phenylglycine is enantiomerically pure, this arising from the formation of bridging azavinylidene (6) and imine intermediate species (7), which were characterized by X-ray diffraction methods
Diverse and Selective Metal–Ligand Cooperative Routes for Activating Non-Functionalized Ketones
No full textThe rhodium and iridium complexes [Cp*M(κ3N,N′,N″-L)][SbF6] (Cp* = η5-C5Me5; M = Rh, 1; Ir, 2; HL = pyridinyl-amidine ligand) exhibit three different cooperative metal–ligand reactivity modes when interacting with nonfunctionalized ketones. With the methyl ketones CH3COR (R = CH3, Ph, CF3), activation of the ketone methyl C(sp3)–H bond yields ketonyl compounds of formula [Cp*M(CH2COR)(κ2N,N′-HL)][SbF6]. With the ketones (CF3)2CO and CF3COPh, the complexes add to the C═O double bond of the ketone. The addition of the iridium compound 2 occurs across the metal atom and the exocyclic carbon of the dearomatized pyridinyl moiety, and that of the rhodium analogue 1 takes place through the rhodium atom and the exocyclic methylene carbon of the Cp* ligand of the intermediate fulvene complex. In the rhodium case, the resulting metal-alkoxide derivative evolves to give rise to rhodium derivatives containing up to four added ketone molecules. In all of these processes, no additives are required, rendering them atom 100% efficient procedures for bond activation. From a mechanistic point of view, DFT calculation reveals that the diverse and selective behavior of 1 and 2 toward ketones can be explained by invoking three different intermediates, each driving the process through distinct reaction pathways
First insights into the life history of the early Miocene deer Procervulus ginsburgi from Spain
No full textThe small‐sized cervid Procervulus is considered as the most basal member of the Cervidae and one of the earliest ruminants bearing antler‐like appendages. The Iberian Miocene record of this stem‐cervid is extensively documented and largely overlaps with the Miocene Climatic Optimum (MCO), a transient period of global warming of particular interest when comparing present and near future conditions. Despite receiving a substantial amount of attention, histological studies on Procervulus are very scarce and only limited to postcranial remains of Procervulus praelucidus from Germany (MN3). Here we focus for the first time on the dental histology of Procervulus ginsburgi from the Early Miocene Iberian site of Artesilla (MN4, 16.49 Ma), and examine its daily enamel secretion rate (DSR), enamel extension rate (EER) and crown formation time (CFT). Results reveal a brief CTF and high DSR and EER for P. ginsburgi and suggest a fast development at least early in its ontogeny. In addition, the pronounced growth rate of P. ginsburgi emerges as higher than that of the roe deer C. capreolus—documented as an r‐strategist and here examined as a possible extant analog. Overall, our findings point toward a fast life history strategy for P. ginsburgi, which unexpectedly contrasts with that of the 2 million‐year‐older P. praelucidus from Wintershof‐West, with a marked slower growth and maturation. When these results are analyzed together with other evidence, the somewhat drier and more open conditions of Artesilla as a result of the effects of the MCO seem to be the explanation for the different life history and ecology between these Procervulus species. More generally, this study illustrates that life histories within a single genus evolve in response not only to internal constraints but also to the environments, as predicted by the Life History Theory
Validity of the MED4CHILD tool for assessing adherence to the Mediterranean diet in preschool children
Get PDFMost of the available tools to assess adherence to Mediterranean diet (MedDiet) were constructed for adults, having limited applicability to children and adolescents. The aim of this study is to validate a specific questionnaire to assess adherence to MedDiet in children aged 3 to 6 years (MED4CHILD questionnaire). The validation was performed in a baseline examination of a cohort of children who were recruited in schools in seven cities. Of the total sample of 1509 children, we included 858 children aged 3 to 6 years with complete information on adherence to the MedDiet, food consumption, anthropometry and cardiometabolic characteristics. Adherence to the MedDiet was assessed using an 18-item questionnaire, adapted from validated questionnaire for adults using the Delphi method. Food and beverage consumption was assessed using a validated COME-Kids Food and Beverage Frequency Questionnaire. Anthropometric measurements and cardiometabolic risk factors were assessed using standard methods. Statistical analyses included kappa agreement, ANOVA and linear regression models. Higher MED4CHILD scores were associated with higher intakes of food characteristic of the MedDiet. The MED4CHILD questionnaire showed moderate validity, especially for key items of the Mediterranean diet (kappa ranging from 0.333 to 0.665). Direct significant associations were found between MED4CHILD scores and cardiometabolic profile, including waist circumference (p), triglycerides and HOMA-IR (p < 0.05).
Conclusion: The 18-item MED4CHILD questionnaire showed moderate validity for assessing adherence to the MedDiet in children aged 3 to 6 years, in terms of agreement with food and beverage consumption and favourable cardiometabolic profile.
What is known: • The Mediterranean diet has been linked to a number of health benefits and the assessment of children's adherence to this diet is important for public health and research. • The tools available to assess MedDiet compliance are mainly for adults.
What is new: • The MED4CHILD questionnaire is a simple, inexpensive and rapid tool for assessing MedDiet compliance in children. • This tool showed moderate relative validity and a high score was associated with a favourable cardiometabolic profile
Trends in adherence to physical activity guidelines from 1997 to 2018 among adults with obesity: An analysis from the US National Health Interview Survey
Get PDFThe aim of this study was to estimate the temporal trends in adherence rates to the physical activity (PA) guidelines for aerobic and muscle‐strengthening activities (MSA) among United States (US) adults with obesity. We retrieved data from 22 consecutive rounds of the National Health Interview Survey (NHIS) conducted between 1997 and 2018. Meeting with the PA guidelines recommended by the World Health Organization was determined as follows: individuals achieving ≥150 weekly minutes of moderate physical activity (MPA), ≥75 weekly minutes of vigorous physical activity (VPA), and ≥2 weekly MSA training sessions. The prevalence of meeting PA guidelines increased from 9.4% in 1997 to 15.0% in 2018, although less than 2 in 10 adults with obesity met the guidelines throughout the study period. Overall, compared to females, males with obesity were more likely to adhere to PA recommendations (odds ratio (OR) = 2.03 [95% confidence interval (CI), 1.94 to 2.12]). Also, each age year significantly reduced the odds of adhering to PA recommendations overall (OR = 0.97 [95% CI, 0.97 to 0.98]). Compared with their White counterparts, Black and other races people with obesity have higher significant odds of adhering to PA recommendations with, respectively, OR = 1.18 (95% CI, 1.12 to 1.24) and OR = 1.30 (95% CI, 1.18 to 1.43). In representative samples of adults with obesity from the US, there was an increasing trend for meeting PA guidelines, although only less than 2 in 10 met them
Molecular analysis of cryptosporidiosis on cattle farms in Gran Canaria, Canary Islands (Spain)
Get PDFCryptosporidium spp. infections in calves cause serious economic losses in livestock and pose an important zoonotic risk. The aim of this study was to investigate the prevalence of Cryptosporidium spp. in cattle on the island of Gran Canaria. Faecal samples were collected from calves and adult cattle from a total of 15 farms, and a questionnaire survey was conducted to farmers. The presence of Cryptosporidium spp. oocysts in faeces was determined by microscopy, showing infection rates of 45.9% in calves and 4.1% in adults, with positive correlation with the faecal scores of infected animals (p < 0.0001). Samples were amplified by PCR targeting SSU rRNA, with positivity rates for calves and adults being 51.7% and 31.7%, respectively. The PCR-positive samples were further genotyped and sequenced for the 60 kDa glycoprotein gene (GP60) and the microsatellite TP14. Four Cryptosporidium species were identified (C. parvum, C. ryanae, C. bovis, and C. andersoni), of which C. parvum was the most frequent in calves (45.8%) and adults (29.2%). GP60 sequencing revealed that all C. parvum samples belonged to the IId family, the most frequent subtypes being IIdA22G1 and IIdA23G1. Overall, the results of this study demonstrate a high occurrence of Cryptosporidium spp. in both calves and adult cattle, including the zoonotic IId family of C. parvum. These findings have significant implications for cattle farming and public health. The lack of awareness among farmers regarding cryptosporidiosis highlights the need for caution to prevent epidemiological outbreaks that could impact both human and livestock health
Novel cisplatin-magnetoliposome complex shows enhanced antitumor activity via Hyperthermia
Get PDFThere are several methods to improve cancer patient survival rates by inducing hyperthermia in tumor tissues, which involves raising their temperature above 41 °C. These methods utilize different energy sources to deliver heat to the target region, including light, microwaves or radiofrequency electromagnetic fields. We have developed a new, magnetically responsive nanocarrier, consisting of liposomes loaded with magnetic nanoparticles and cis-diamminedichloroplatinum (II) (CDDP), commonly known as Cisplatin. The resulting magnetoliposome (ML) is rapidly internalized by lung and pancreas tumor cell lines, stored in intracellular vesicles, and capable of inducing hyperthermia under magnetic fields. The ML has no significant toxicity both in vitro and in vivo and, most importantly, enhances cell death by apoptosis after magnetic hyperthermia. Remarkably, mice bearing induced lung tumors, treated with CDDP-loaded nanocarriers and subjected to an applied electromagnetic field, showed an improved survival rate over those treated with either soluble CDDP or hyperthermia alone. Therefore, our approach of magnetic hyperthermia plus CDDP-ML significantly enhances in vitro cell death and in vivo survival of treated animals
Metal-organic frameworks/graphene oxide nanohybrids to control pore wetting in membrane distillation
Get PDFMembrane distillation (MD) is an emerging technology in the field of water desalination due to its high-energy efficiency and the fact that is not affected by feed salt concentration. As an alternative to feed water pre-treatment, membrane surface modification aims at changing different properties to make it less prone to fouling. This work addresses the mitigation of the most concerning membrane degradation effects in MD, such as pore wetting and fouling, by modifying the membrane surface. This work takes advantage of the adsorption properties of metal-organic frameworks (MOF)@graphene oxide (GO) nanohybrids to create sacrificial sites (located zones where adsorption of foulants is facilitated) on the membrane surface. MOF@GO nanohybrids are embedded between two polydopamine (PDA) layers that are deposited on top of commercial polyethylene (PE) membranes. Two types of MOF@GO nanohybrids were evaluated, one containing UiO-66-NH2 and the other one ZIF-8. Air gap membrane distillation (AGMD) experiments using highly concentrated foulant solutions to accelerate the effects of membrane degradation, showed that surface modification effectively extended membrane life. The selective foulant adsorption delayed pore wetting and allowed to retain most of the membrane flux. Pore wetting occurred after 109 h for the membrane containing ZIF-8@GO (500 mg·m−2), compared to 4–5 h for the unmodified commercial membrane. Due to their high adsorption properties, the presence of MOFs is essential to ensure the formation of sacrificial sites and to maintain the initial flux, thus higher fluxes were observed for MOF@GO membranes (13 kg·m−2·h−1), compared to those containing only GO (5 kg·m−2·h−1)