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2.
PLoS Biol ; 20(6): e3001674, 2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-35709146

RESUMO

Understanding tropical biology is important for solving complex problems such as climate change, biodiversity loss, and zoonotic pandemics, but biology curricula view research mostly via a temperate-zone lens. Integrating tropical research into biology education is urgently needed to tackle these issues.


Assuntos
Biodiversidade , Mudança Climática , Biologia , Clima Tropical
3.
Am J Physiol Renal Physiol ; 326(5): F727-F736, 2024 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-38511219

RESUMO

Although obesity is recognized as a risk factor for cardiorenal and metabolic diseases, the impact of parental obesity on the susceptibility of their offspring to renal injury at adulthood is unknown. We examined the impact of parental obesity on offspring kidney function, morphology, and markers of kidney damage after acute kidney injury (AKI). Offspring from normal (N) diet-fed C57BL/6J parents were fed either N (NN) or a high-fat (H) diet (NH) from weaning until adulthood. Offspring from obese H diet-fed parents were fed N (HN) or H diet (HH) after weaning. All offspring groups were submitted to bilateral AKI by clamping the left and right renal pedicles for 30 min. Compared with male NH and NN offspring from lean parents, male HH and HN offspring from obese parents exhibited higher kidney injury markers such as urinary, renal osteopontin, plasma creatinine, urinary albumin excretion, and neutrophil gelatinase-associated lipocalin (NGAL) levels, and worse histological injury score at 22 wk of age. Only albumin excretion and NGAL were elevated in female HH offspring from obese parents compared with lean and obese offspring from lean parents. We also found an increased mortality rate and worse kidney injury scores after AKI in male offspring from obese parents, regardless of the diet consumed after weaning. Female offspring were protected from major kidney injury after AKI. These results indicate that parental obesity leads to increased kidney injury in their offspring after ischemia-reperfusion in a sex-dependent manner, even when their offspring remain lean.NEW & NOTEWORTHY Offspring from obese parents are more susceptible to kidney injury and worse outcomes following an acute ischemia-reperfusion insult. Male, but not female, offspring from obese parents exhibit increased blood pressure early in life. Female offspring are partially protected against major kidney injury induced by ischemia-reperfusion.


Assuntos
Injúria Renal Aguda , Rim , Camundongos Endogâmicos C57BL , Traumatismo por Reperfusão , Animais , Masculino , Feminino , Traumatismo por Reperfusão/patologia , Traumatismo por Reperfusão/metabolismo , Injúria Renal Aguda/etiologia , Injúria Renal Aguda/metabolismo , Injúria Renal Aguda/fisiopatologia , Injúria Renal Aguda/patologia , Rim/fisiopatologia , Rim/patologia , Rim/metabolismo , Fatores Sexuais , Obesidade/complicações , Obesidade/fisiopatologia , Dieta Hiperlipídica , Gravidez , Lipocalina-2/metabolismo , Obesidade Materna/metabolismo , Obesidade Materna/complicações , Obesidade Materna/fisiopatologia , Efeitos Tardios da Exposição Pré-Natal , Camundongos , Fatores de Risco , Modelos Animais de Doenças , Biomarcadores/sangue
4.
Chemistry ; 30(28): e202303809, 2024 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-38465520

RESUMO

Patterning of graphene (functionalizing some areas while leaving others intact) is challenging, as all the C atoms in the basal plane are identical, but it is also desirable for a variety of applications, like opening a bandgap in the electronic structure of graphene. Several methods have been reported to pattern graphene, but most of them are very technologically intensive. Recently, we reported the use of microemulsions as templates to pattern graphene at the µm scale. This method is very simple and in principle tunable, as emulsions of different droplet size and composition can be prepared easily. Here, we explore in detail the scope of this methodology by applying it to all the combinations of four different emulsions and three different organic reagents, and characterizing the resulting substrates exhaustively through Raman, SEM and AFM. We find that the method is general, works better when the reactive species are outside the micelles, and requires reactive species that involve short reaction times.

5.
Chemistry ; 29(58): e202301490, 2023 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-37452643

RESUMO

Single-walled carbon nanotubes (SWNTs) present extraordinary mechanical properties, with Youngs' modulus>1 TPa and tensile strength>50 GPa; this makes them ideal candidates as fillers for the reinforcement of polymers. However, the performance of SWNTs in this field has fallen behind expectations. This is due to a combination of imperfect individualization of the SWNTs and poor load transfer from the polymer to the SWNTs. Here, we study the reinforcement of polymers of different chemical nature using mechanically interlocked derivatives of single-walled carbon nanotubes (MINTs). We compare the mechanical properties of fibers made of poly (methyl methacrylate) (PMMA) and polysulfone (PSU) and their composites made with pristine SWNTs, MINTs, and the corresponding supramolecular models. With very low loading of MINTs (0.01 % w/w), improvements of more than 100 % on Youngs Modulus and the tensile strength are observed for both the nonpolar aliphatic PMMA and the very polar aromatic PSU polymers, while pristine carbon nanotubes and the supramolecular nanofillers showed smaller reinforcement. These data, together with our previous report on the reinforcement of polystyrene (nonpolar and aromatic), indicate that derivatization of SWNTs as MINTs is a valid general strategy to optimize the interaction between SWNT fillers and the polymer matrix.

6.
Vasc Med ; 28(4): 324-330, 2023 08.
Artigo em Inglês | MEDLINE | ID: mdl-37272085

RESUMO

BACKGROUND: The natural history of patients with a pacemaker-related upper-extremity deep vein thrombosis (UEDVT) has not been consistently studied. METHODS: We used the RIETE registry data to compare the outcomes during anticoagulation and after its discontinuation in noncancer patients with symptomatic UEDVT associated with a pacemaker, other catheters, or no catheter. The major outcome was the composite of symptomatic pulmonary embolism or recurrent DVT. RESULTS: As of February 2022, 2578 patients with UEDVT were included: 156 had a pacemaker-related UEDVT, 557 had other catheters, and 1865 had no catheter. During anticoagulation, 61 patients (2.3%) developed recurrent VTE, 38 had major bleeding (1.4%), and 90 died (3.4%). After its discontinuation, 52 patients (4.4%) had recurrent acute venous thromboembolism (VTE) and six had major bleeding (0.5%). On multivariable analysis, there were no differences among subgroups in the rates of VTE recurrences or major bleeding during anticoagulation. After its discontinuation, patients with a pacemaker-related UEDVT had a higher risk for VTE recurrences than those with no catheter (adjusted OR: 4.59; 95% CI: 1.98-10.6). CONCLUSIONS: Patients with pacemaker-related UEDVT are at increased risk for VTE recurrences after discontinuing anticoagulation. If our findings are validated in adequately designed trials, this may justify changes in the current recommendations on the duration of anticoagulation.


Assuntos
Neoplasias , Embolia Pulmonar , Trombose Venosa Profunda de Membros Superiores , Tromboembolia Venosa , Trombose Venosa , Humanos , Tromboembolia Venosa/etiologia , Fatores de Risco , Trombose Venosa Profunda de Membros Superiores/diagnóstico por imagem , Trombose Venosa Profunda de Membros Superiores/etiologia , Trombose Venosa/diagnóstico , Trombose Venosa/tratamento farmacológico , Trombose Venosa/induzido quimicamente , Embolia Pulmonar/induzido quimicamente , Hemorragia/induzido quimicamente , Neoplasias/complicações , Neoplasias/diagnóstico , Anticoagulantes/efeitos adversos , Recidiva , Extremidades
7.
Chem Soc Rev ; 51(23): 9433-9444, 2022 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-36239532

RESUMO

Single-walled carbon nanotubes (SWNTs) present one of the most interesting collections of properties among nanomaterials. Some sort of chemical modification of SWNTs is often used as a strategy to make the most of their intrinsic properties. In the last few years, the mechanical bond has been added to the chemistry toolbox for SWNT modification. In this Tutorial Review, we first discuss the characteristics of the mechanical bond that make it appealing for materials science in general and SWNTs in particular. We then describe the potential advantages of making mechanically-interlocked derivatives of SWNTs (MINTs), as compared to covalent or classic supramolecular derivatives of SWNTs. We go on to explain the different methods of synthesis of MINTs, highlighting their common features as an indication towards possible future synthetic strategies. Finally, we illustrate with examples how the making of MINTs can contribute to modifying the surface properties of SWNTs, modulating their electronic properties, and linking them to functional molecular fragments. The overall objective of this Review is to introduce the reader to the application of the chemistry of the mechanical bond to SWNTs: why it is relevant, how it is done in practice, what it has shown already as potential contributions towards applications, and what could be done in the future.


Assuntos
Nanotubos de Carbono , Nanotubos de Carbono/química , Eletrônica , Propriedades de Superfície
8.
Angew Chem Int Ed Engl ; 62(6): e202212395, 2023 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-36445791

RESUMO

Nanocars are carbon-based single-molecules with a precise design that facilitates their atomic-scale control on a surface. The rational design of these molecules is important in atomic and molecular-scale manipulation to advance the development of molecular machines, as well as for a better understanding of self-assembly, diffusion and desorption processes. Here, we introduce the molecular design and construction of a collection of minimalistic nanocars. They feature an anthracene chassis and four benzene derivatives as wheels. After sublimation and adsorption on an Au(111) surface, we show controlled and fast manipulation of the nanocars along the surface using the tip of a scanning tunneling microscope (STM). The mechanism behind the successful displacement is the induced dipole created over the nanocar by the STM tip. We utilized carbon monoxide functionalized tips both to avoid decomposition and accidentally picking the nanocars up during the manipulation. This strategy allowed thousands of maneuvers to successfully win the Nanocar Race II championship.

9.
Glob Chang Biol ; 28(2): 463-479, 2022 01.
Artigo em Inglês | MEDLINE | ID: mdl-34697872

RESUMO

Deforestation often results in landscapes where remaining forest habitat is highly fragmented, with remnants of different sizes embedded in an often highly contrasting matrix. Local extinction of species from individual fragments is common, but the demographic mechanisms underlying these extinctions are poorly understood. It is often hypothesized that altered environmental conditions in fragments drive declines in reproduction, recruitment, or survivorship. The Amazon basin, in addition to experiencing continuing fragmentation, is experiencing climate change-related increases in the frequency and intensity of droughts and unusually wet periods. Whether plant populations in tropical forest fragments are particularly susceptible to extremes in precipitation remains unclear. Most studies of plants in fragments are relatively short (1-6 years), focus on a single life-history stage, and often do not compare to populations in continuous forest. Even fewer studies consider delayed effects of climate on demographic vital rates despite the importance of delayed effects in studies that consider them. Using a decade of demographic and climate data from an experimentally fragmented landscape in the Central Amazon, we assess the effects of climate on populations of an understory herb (Heliconia acuminata, Heliconiaceae). We used distributed lag nonlinear models to understand the delayed effects of climate (measured as standardized precipitation evapotranspiration index, SPEI) on survival, growth, and flowering. We detected delayed effects of climate up to 36 months. Extremes in SPEI in the previous year reduced survival, drought in the wet season 8-11 months prior to the February census increased growth, and drought two dry seasons prior increased flowering probability. Effects of extremes in precipitation on survival and growth were more pronounced in forest fragments compared to continuous forest. The complex delayed effects of climate and habitat fragmentation in our study point to the importance of long-term demography experiments in understanding the effects of anthropogenic change on plant populations.


Assuntos
Mudança Climática , Florestas , Demografia , Secas , Ecossistema , Clima Tropical
10.
J Pathol ; 254(2): 147-158, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-33904171

RESUMO

Artificial intelligence (AI)-based systems applied to histopathology whole-slide images have the potential to improve patient care through mitigation of challenges posed by diagnostic variability, histopathology caseload, and shortage of pathologists. We sought to define the performance of an AI-based automated prostate cancer detection system, Paige Prostate, when applied to independent real-world data. The algorithm was employed to classify slides into two categories: benign (no further review needed) or suspicious (additional histologic and/or immunohistochemical analysis required). We assessed the sensitivity, specificity, positive predictive values (PPVs), and negative predictive values (NPVs) of a local pathologist, two central pathologists, and Paige Prostate in the diagnosis of 600 transrectal ultrasound-guided prostate needle core biopsy regions ('part-specimens') from 100 consecutive patients, and to ascertain the impact of Paige Prostate on diagnostic accuracy and efficiency. Paige Prostate displayed high sensitivity (0.99; CI 0.96-1.0), NPV (1.0; CI 0.98-1.0), and specificity (0.93; CI 0.90-0.96) at the part-specimen level. At the patient level, Paige Prostate displayed optimal sensitivity (1.0; CI 0.93-1.0) and NPV (1.0; CI 0.91-1.0) at a specificity of 0.78 (CI 0.64-0.89). The 27 part-specimens considered by Paige Prostate as suspicious, whose final diagnosis was benign, were found to comprise atrophy (n = 14), atrophy and apical prostate tissue (n = 1), apical/benign prostate tissue (n = 9), adenosis (n = 2), and post-atrophic hyperplasia (n = 1). Paige Prostate resulted in the identification of four additional patients whose diagnoses were upgraded from benign/suspicious to malignant. Additionally, this AI-based test provided an estimated 65.5% reduction of the diagnostic time for the material analyzed. Given its optimal sensitivity and NPV, Paige Prostate has the potential to be employed for the automated identification of patients whose histologic slides could forgo full histopathologic review. In addition to providing incremental improvements in diagnostic accuracy and efficiency, this AI-based system identified patients whose prostate cancers were not initially diagnosed by three experienced histopathologists. © 2021 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.


Assuntos
Inteligência Artificial , Neoplasias da Próstata/diagnóstico , Idoso , Idoso de 80 Anos ou mais , Biópsia , Biópsia com Agulha de Grande Calibre , Humanos , Aprendizado de Máquina , Masculino , Pessoa de Meia-Idade , Patologistas , Próstata/patologia , Neoplasias da Próstata/patologia
11.
J Dairy Sci ; 105(12): 9297-9326, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36270879

RESUMO

Ruminant livestock are an important source of anthropogenic methane (CH4). Decreasing the emissions of enteric CH4 from ruminant production is strategic to limit the global temperature increase to 1.5°C by 2050. Research in the area of enteric CH4 mitigation has grown exponentially in the last 2 decades, with various strategies for enteric CH4 abatement being investigated: production intensification, dietary manipulation (including supplementation and processing of concentrates and lipids, and management of forage and pastures), rumen manipulation (supplementation of ionophores, 3-nitrooxypropanol, macroalgae, alternative electron acceptors, and phytochemicals), and selection of low-CH4-producing animals. Other enteric CH4 mitigation strategies are at earlier stages of research but rapidly developing. Herein, we discuss and analyze the current status of available enteric CH4 mitigation strategies with an emphasis on opportunities and barriers to their implementation in confined and partial grazing production systems, and in extensive and fully grazing production systems. For each enteric CH4 mitigation strategy, we discuss its effectiveness to decrease total CH4 emissions and emissions on a per animal product basis, safety issues, impacts on the emissions of other greenhouse gases, as well as other economic, regulatory, and societal aspects that are key to implementation. Most research has been conducted with confined animals, and considerably more research is needed to develop, adapt, and evaluate antimethanogenic strategies for grazing systems. In general, few options are currently available for extensive production systems without feed supplementation. Continuous research and development are needed to develop enteric CH4 mitigation strategies that are locally applicable. Information is needed to calculate carbon footprints of interventions on a regional basis to evaluate the impact of mitigation strategies on net greenhouse gas emissions. Economically affordable enteric CH4 mitigation solutions are urgently needed. Successful implementation of safe and effective antimethanogenic strategies will also require delivery mechanisms and adequate technical support for producers, as well as consumer involvement and acceptance. The most appropriate metrics should be used in quantifying the overall climate outcomes associated with mitigation of enteric CH4 emissions. A holistic approach is required, and buy-in is needed at all levels of the supply chain.


Assuntos
Gases de Efeito Estufa , Metano , Animais , Metano/análise , Biodiversidade , Temperatura , Ruminantes
12.
Int J Mol Sci ; 23(22)2022 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-36430510

RESUMO

Protein kinase C (PKC) comprises a family of highly related serine/threonine protein kinases involved in multiple signaling pathways, which control cell proliferation, survival, and differentiation. The role of PKCα in cancer has been studied for many years. However, it has been impossible to establish whether PKCα acts as an oncogene or a tumor suppressor. Here, we analyzed the importance of PKCα in cellular processes such as proliferation, migration, or apoptosis by inhibiting its gene expression in a luminal A breast cancer cell line (MCF-7). Differential expression analysis and phospho-kinase arrays of PKCα-KD vs. PKCα-WT MCF-7 cells identified an essential set of proteins and oncogenic kinases of the JAK/STAT and PI3K/AKT pathways that were down-regulated, whereas IGF1R, ERK1/2, and p53 were up-regulated. In addition, unexpected genes related to the interferon pathway appeared down-regulated, while PLC, ERBB4, or PDGFA displayed up-regulated. The integration of this information clearly showed us the usefulness of inhibiting a multifunctional kinase-like PKCα in the first step to control the tumor phenotype. Then allowing us to design a possible selection of specific inhibitors for the unexpected up-regulated pathways to further provide a second step of treatment to inhibit the proliferation and migration of MCF-7 cells. The results of this study suggest that PKCα plays an oncogenic role in this type of breast cancer model. In addition, it reveals the signaling mode of PKCα at both gene expression and kinase activation. In this way, a wide range of proteins can implement a new strategy to fine-tune the control of crucial functions in these cells and pave the way for designing targeted cancer therapies.


Assuntos
Neoplasias , Proteína Quinase C-alfa , Humanos , Proteína Quinase C-alfa/genética , Proteína Quinase C-alfa/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Transdução de Sinais , Proteína Quinase C/metabolismo , Proliferação de Células
13.
Angew Chem Int Ed Engl ; 61(35): e202208189, 2022 Aug 26.
Artigo em Inglês | MEDLINE | ID: mdl-35789180

RESUMO

Mechanically interlocked derivatives of carbon nanotubes (MINTs) are interesting nanotube products since they show high stability without altering the carbon nanotube structure. So far, MINTs have been synthesized using ring-closing metathesis, disulfide exchange reaction, H-bonding or direct threading with macrocycles. Here, we describe the encapsulation of single-walled carbon nanotubes within a palladium-based metallosquare. The formation of MINTs was confirmed by a variety of techniques, including high-resolution transmission electron microscopy. We find the making of these MINTs is remarkably sensitive to structural variations of the metallo-assemblies. When a metallosquare with a cavity of appropriate shape and size is used, the formation of the MINT proceeds successfully by both templated clipping and direct threading. Our studies also show indications on how supramolecular coordination complexes can help expand the potential applications of MINTs.

14.
J Am Chem Soc ; 143(50): 21286-21293, 2021 Dec 22.
Artigo em Inglês | MEDLINE | ID: mdl-34825564

RESUMO

Atomic-scale reproducibility and tunability endorse magnetic molecules as candidates for spin qubits and spintronics. A major challenge is to implant those molecular spins into circuit geometries that may allow one, two, or a few spins to be addressed in a controlled way. Here, the formation of mechanically bonded, magnetic porphyrin dimeric rings around carbon nanotubes (mMINTs) is presented. The mechanical bond places the porphyrin magnetic cores in close contact with the carbon nanotube without disturbing their structures. A combination of spectroscopic techniques shows that the magnetic geometry of the dimers is preserved upon formation of the macrocycle and the mMINT. Moreover, the metallic core selection determines the spin location in the mMINT. The suitability of mMINTs as qubits is explored by measuring their quantum coherence times (Tm). Formation of the dimeric ring preserves the Tm found in the monomer, which remains in the µs scale for mMINTs. The carbon nanotube is used as vessel to place the molecules in complex circuits. This strategy can be extended to other families of magnetic molecules. The size and composition of the macrocycle can be tailored to modulate magnetic interactions between the cores and to introduce magnetic asymmetries (heterometallic dimers) for more complex molecule-based qubits.

15.
Chemistry ; 27(9): 2993-2996, 2021 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-33231902

RESUMO

The combination of 2D materials opens a wide range of possibilities to create new-generation structures with multiple applications. Covalently cross-linked approaches are a ground-breaking strategy for the formation of homo or heterostructures made by design. However, the covalent assembly of transition metal dichalcogenides flakes is relatively underexplored. Here, a simple covalent cross-linking method to build 2H-MoS2 -MoS2 homostructures is described, using commercially available bismaleimides. These assemblies are mainly connected vertically, basal plane to basal plane, creating specific molecular sized spaces between MoS2 sheets. Therefore, this straightforward approach gives access to the controlled connection of sulfide-based 2D materials.

16.
Br J Nutr ; 125(6): 601-610, 2021 03 28.
Artigo em Inglês | MEDLINE | ID: mdl-32718369

RESUMO

The present study investigated the association between fibre degradation and the concentration of dissolved molecular hydrogen (H2) in the rumen. Napier grass (NG) silage and corn stover (CS) silage were compared as forages with contrasting structures and degradation patterns. In the first experiment, CS silage had greater 48-h DM, neutral-detergent fibre (NDF) and acid-detergent fibre degradation, and total gas and methane (CH4) volumes, and lower 48-h H2 volume than NG silage in 48-h in vitro incubations. In the second experiment, twenty-four growing beef bulls were fed diets including 55 % (DM basis) NG or CS silages. Bulls fed the CS diet had greater DM intake (DMI), average daily gain, total-tract digestibility of OM and NDF, ruminal dissolved methane (dCH4) concentration and gene copies of protozoa, methanogens, Ruminococcus albus and R. flavefaciens, and had lower ruminal dH2 concentration, and molar proportions of valerate and isovalerate, in comparison with those fed the NG diet. There was a negative correlation between dH2 concentration and NDF digestibility in bulls fed the CS diet, and a lack of relationship between dH2 concentration and NDF digestibility with the NG diet. In summary, the fibre of CS silage was more easily degraded by rumen microorganisms than that of NG silage. Increased dCH4 concentration with the CS diet presumably led to the decreased ruminal dH2 concentration, which may be helpful for fibre degradation and growth of fibrolytic micro-organisms in the rumen.


Assuntos
Bovinos/fisiologia , Fibras na Dieta/metabolismo , Digestão , Microbioma Gastrointestinal , Hidrogênio/análise , Rúmen/metabolismo , Silagem , Animais , Bovinos/crescimento & desenvolvimento , Dieta , Fibras na Dieta/administração & dosagem , Euryarchaeota/classificação , Euryarchaeota/genética , Euryarchaeota/metabolismo , Masculino , Metano/análise , Poaceae , Rúmen/microbiologia , Rúmen/parasitologia , Ruminococcus/classificação , Ruminococcus/genética , Ruminococcus/metabolismo , Silagem/análise , Zea mays
17.
Trop Anim Health Prod ; 53(1): 123, 2021 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-33447921

RESUMO

Efficient utilization of locally available feed resources is needed for further development of livestock productions in the tropics. However, an inadequate supply of nourish grass is common, and limited information exists regarding the chemical composition and digestibility of locally available feed resources in the different season. There were few reliable information concerning nutritive value of Gramineae resources in dry and rainy seasons in the Philippines. Hence, the present study was conducted to identify the chemical composition and in vitro digestibility of nine kinds of locally available Gramineae feed resources in dry and rainy seasons in the Philippines. The concentration of dry matter (DM), crude protein, and crude fiber of grass samples did not differ among species and seasons. The concentration of organic matter (OM), ether extract (EE), crude ash (CA), nitrogen-free extract (NFE), acid detergent fiber, and neutral detergent fiber (NDF) of grass samples differed significantly among species in both seasons except the NDF in the rainy season. However, the OM, CA, and NDF concentrations of the samples showed no differences between seasons. Imperata cylindrica showed the highest concentration of OM among the samples. Brachiaria brizantha had the lowest EE concentration among the grasses. The lowest NFE concentration was identified in Panicum maximum among the grasses. Although the digestibility of DM (DMD), OM (OMD), and NDF (NDFD) of grass samples showed significant differences among species. The DMD, OMD, and NDFD of I. cylindrica were the lowest among the samples, though Pennisetum purpureum showed the highest DMD, OMD, and NDFD among the species. Relatively high nutritive values of P. purpureum were remarkable among the samples in the present survey area.


Assuntos
Ração Animal , Digestão , Poaceae/química , Ração Animal/análise , Animais , Fibras na Dieta/análise , Filipinas
18.
Chemistry ; 26(29): 6629-6634, 2020 May 20.
Artigo em Inglês | MEDLINE | ID: mdl-32101348

RESUMO

Most air-stable 2D materials are relatively inert, which makes their chemical modification difficult. In particular, in the case of MoS2 , the semiconducting 2 H-MoS2 is much less reactive than its metallic counterpart, 1T-MoS2 . As a consequence, there are hardly any reliable methods for the covalent modification of 2 H-MoS2 . An ideal method for the chemical functionalization of such materials should be both mild, not requiring the introduction of a large number of defects, and versatile, allowing for the decoration with as many different functional groups as possible. Herein, a comprehensive study on the covalent functionalization of 2 H-MoS2 with maleimides is presented. The use of a base (Et3 N) leads to the in situ formation of a succinimide polymer layer, covalently connected to MoS2 . In contrast, in the absence of base, functionalization stops at the molecular level. Moreover, the functionalization protocol is mild (occurs at room temperature), fast (nearly complete in 1 h), and very flexible (11 different solvents and 10 different maleimides tested). In practical terms, the procedures described here allow for the chemist to manipulate 2 H-MoS2 in a very flexible way, decorating it with polymers or molecules, and with a wide range of functional groups for subsequent modification. Conceptually, the spurious formation of an organic polymer might be general to other methods of functionalization of 2D materials, where a large excess of molecular reagents is typically used.

19.
PLoS Biol ; 15(12): e2002760, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-29232375

RESUMO

The scholars comprising journal editorial boards play a critical role in defining the trajectory of knowledge in their field. Nevertheless, studies of editorial board composition remain rare, especially those focusing on journals publishing research in the increasingly globalized fields of science, technology, engineering, and math (STEM). Using metrics for quantifying the diversity of ecological communities, we quantified international representation on the 1985-2014 editorial boards of 24 environmental biology journals. Over the course of 3 decades, there were 3,827 unique scientists based in 70 countries who served as editors. The size of the editorial community increased over time-the number of editors serving in 2014 was 4-fold greater than in 1985-as did the number of countries in which editors were based. Nevertheless, editors based outside the "Global North" (the group of economically developed countries with high per capita gross domestic product [GDP] that collectively concentrate most global wealth) were extremely rare. Furthermore, 67.18% of all editors were based in either the United States or the United Kingdom. Consequently, geographic diversity-already low in 1985-remained unchanged through 2014. We argue that this limited geographic diversity can detrimentally affect the creativity of scholarship published in journals, the progress and direction of research, the composition of the STEM workforce, and the development of science in Latin America, Africa, the Middle East, and much of Asia (i.e., the "Global South").


Assuntos
Biologia , Ecologia , Políticas Editoriais , Internacionalidade , Editoração , Estados Unidos
20.
Nature ; 508(7494): 72-5, 2014 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-24670644

RESUMO

Hitherto, rings have been found exclusively around the four giant planets in the Solar System. Rings are natural laboratories in which to study dynamical processes analogous to those that take place during the formation of planetary systems and galaxies. Their presence also tells us about the origin and evolution of the body they encircle. Here we report observations of a multichord stellar occultation that revealed the presence of a ring system around (10199) Chariklo, which is a Centaur--that is, one of a class of small objects orbiting primarily between Jupiter and Neptune--with an equivalent radius of 124 ± 9 kilometres (ref. 2). There are two dense rings, with respective widths of about 7 and 3 kilometres, optical depths of 0.4 and 0.06, and orbital radii of 391 and 405 kilometres. The present orientation of the ring is consistent with an edge-on geometry in 2008, which provides a simple explanation for the dimming of the Chariklo system between 1997 and 2008, and for the gradual disappearance of ice and other absorption features in its spectrum over the same period. This implies that the rings are partly composed of water ice. They may be the remnants of a debris disk, possibly confined by embedded, kilometre-sized satellites.

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