Graphene as a nano-delivery vehicle in agriculture - current knowledge and future prospects.

Graphene has triggered enormous interest in, and exploration of, its applications in diverse areas of science and technology due to its unique properties. While graphene has displayed great potential as a nano-delivery system for drugs and biomolecules in biomedicine, its application as a nanocarrier in agriculture has only begun to be explored. Conventional fertilizers and agricultural delivery systems have a number of disadvantages, such as: fast release of the active ingredient, low delivery efficiency, rapid degradation and low stability that often leads to their over-application and consequent environmental problems. Advanced nano fertilizers with high carrier efficiency and slow and controlled release are now considered the gold standard for promoting agricultural sustainability while protecting the environment. Graphene's attractive properties include large surface area, chemical stability, mechanical stability, tunable surface chemistry and low toxicity making it a promising material on which to base agricultural delivery systems. Recent research has demonstrated considerable success in the use of graphene for agricultural applications, including its utilization as a delivery vehicle for plant nutrients and crop protection agents, as well as in post-harvest management of crops. This review, therefore, presents a comprehensive overview of the current status of graphene-based nanocarriers in agriculture. Additionally, the review outlines the surface functionalization methods used for effective molecular delivery, various strategies for nano-vehicle design and the underlying features necessary for a graphene-based agro-delivery system. Finally, the review discusses directions for further research in optimization of graphene-based nanocarriers.

"Being a team of five strong women we had to make an impression:" The College Math Academy as an intervention into mathematics education.

This paper, a first-person account, describes a community psychology-aligned intervention into a precalculus mathematics class at an Hispanic Serving Research Institution. The intervention was designed because the standard precalculus mathematics class had a high failure rate, especially for Latinx students, which was serving as a barrier for declaration of a Science, Technology, Engineering, or Mathematics major. The high failure rate indicates a structural problem that requires a structural intervention. The paper is coauthored with the teaching team, undergraduates who had taken the course, a graduate student who evaluated the class, and a community psychologist. We describe the ways that the new course, the College Math Academy, transformed the social environment through capacity building, providing access to valued resources for historically marginalized groups, facilitating opportunities to critique dominant power structures, prioritizing perspectives and experiences of people of color, and promoting understanding of how various social forces shape culture and values. The course also decentered white educational norms via adapting decoloniality and liberatory practices. In turn, each person describes their experience of the course. We draw on the first-person accounts to show how they illustrate a transformative, decolonial, and liberatory social environment. We end with implications for how community psychologists can work in their universities to support structural change.

Absolute distance measurement with a gain-switched dual optical frequency comb.

The measurement of distance plays an important role in many aspects of modern societies. In this paper, an absolute distance measurement method for arbitrary distance is proposed and demonstrated using mode-resolved spectral interferometry with a gain-switched dual comb. An accuracy of 12 µm, when compared to a He-Ne fringe counting laser interferometer, for a displacement up to 2.5 m is demonstrated by tuning the repetition frequency of the dual comb from 1.1 GHz to 1.4 GHz. The compact measurement system based on a gain-switched dual comb breaks the constraint of periodic ambiguity. The simplification and improvements are significant for further industrial applications.

Laser speckle imaging of flowing blood: A numerical study.

Laser speckle imaging (LSI) can be used to study dynamic processes in turbid media, such as blood flow. However, it is presently still challenging to obtain meaningful quantitative information from speckle, mainly because speckle is the interferometric summation of multiply scattered light. Consequently, speckle represents a convolution of the local dynamics of the medium. In this paper, we present a computational model for simulating the LSI process, which we aim to use for improving our understanding of the underlying physics. Thereby reliable methods for extracting meaningful information from speckle can be developed. To validate our code, we apply it to a case study resembling blood flow: a cylindrical fluid flow geometry seeded with small spherical particles and modulated with a heartbeat signal. From the simulated speckle pattern, we successfully retrieve the main frequency modes of the original heartbeat signal. By comparing Poiseuille flow to plug flow, we show that speckle boiling causes a small amount of uniform spectral noise. Our results indicate that our computational model is capable of simulating LSI and will therefore be useful in future studies for further developing LSI as a quantitative imaging tool.

Adding a spin to Kerker's condition: angular tuning of directional scattering with designed excitation.

We describe a method to control the directional scattering of a high-index dielectric nanosphere, which utilizes the unique focusing properties of an azimuthally polarized phase vortex and a radially polarized beam to independently excite inside the nanosphere a spinning magnetic dipole and a linearly polarized electric dipole mode normal to the magnetic dipole. We show that by simply adjusting the phase and amplitude of the field on the exit pupil of the optical system, the scattering of the nanosphere can be tuned to any direction within a plane, and the method works over a broad wavelength range.

From Materia Medica to the Pharmacopoeia: Challenges of Writing the History of Drugs in India.

Historians of indigenous medicine in colonial India have looked more closely at the changes, reinventions and reformulations of institutions of Ayurveda and Unani than at the cognitive content of the drugs themselves. The few historians who have examined the changing content of indigenous medicines have conceptualised the creation of materia medica of Indian drugs through two tropes: one of circulation (of specific drugs) through epistemological and geographic boundaries and the second, of marginalisation of certain other drugs either through a lack of textual legitimacy or the lack of the newly discovered 'active principles' within each drug. While these approaches have been useful, there is a case to be made for understanding the creation of formularies of Indian drugs in 19th and 20th centuries through the prism of medical praxis in India.

Between the Bazaar and the Bench: Making of the Drugs Trade in Colonial India, ca. 1900-1930.

This article analyzes why adulteration became a key trope of the Indian drug market. Adulteration had a pervasive presence, being present in medical discourses, public opinion and debate, and the nationalist claim for government intervention. The article first situates the roots of adulteration in the composite nature of this market, which involved the availability of drugs of different potencies as well as the presence of multiple layers of manufacturers, agents, and distributors. It then shows that such a market witnessed the availability of drugs of diverse potency and strengths, which were understood as elements of adulteration in contemporary medical and official discourse. Although contemporary critics argued that the lack of government legislation and control allowed adulteration to sustain itself, this article establishes that the culture of the dispensation of drugs in India necessarily involved a multitude of manufacturer-retailers, bazaar traders, and medical professionals practicing a range of therapies.

Mode-resolved frequency comb interferometry for high-accuracy long distance measurement.

Optical frequency combs have developed into powerful tools for distance metrology. In this paper we demonstrate absolute long distance measurement using a single femtosecond frequency comb laser as a multi-wavelength source. By applying a high-resolution spectrometer based on a virtually imaged phased array, the frequency comb modes are resolved spectrally to the level of an individual mode. Having the frequency comb stabilized against an atomic clock, thousands of accurately known wavelengths are available for interferometry. From the spectrally resolved output of a Michelson interferometer a distance is derived. The presented measurement method combines spectral interferometry, white light interferometry and multi-wavelength interferometry in a single scheme. Comparison with a fringe counting laser interferometer shows an agreement within <10(-8) for a distance of 50 m.

Study of the exhaled acetone in type 1 diabetes using quantum cascade laser spectroscopy.

The acetone concentration exhaled in the breath of three type 1 diabetes patients (two minors and one adult) and one healthy volunteer is studied using a quantum cascade laser-based spectroscopic system. Using the acetone signature between 1150 and 1250 cm(-1) and a multiline fitting method, the concentration variations on the order of parts per billion by volume were measured. Blood glucose and ketone concentrations in blood measurements were performed simultaneously to study their relation with acetone in exhaled breath. We focus on personalized studies to better understand the role of acetone in diabetes. For each volunteer, we performed a series of measurements over a period of time, including overnight fastings of 11 ± 1 h and during ketosis-hyperglycemia events for the minors. Our results highlight the importance of performing personalized studies because the response of the minors to the presence of ketosis was consistent but unique for each individual. Also, our results emphasize the need for performing more studies with T1D minors, because the acetone concentration in the breath of the minors differs, with respect to those reported in the literature, which are based on adults.

Leisure, economy and colonial urbanism: Darjeeling, 1835-1930.

This article posits that the hill station of Darjeeling was a unique form of colonial urbanism. It shifts historiographical interest from major urban centres in colonial India (such as Bombay or Calcutta) and instead attempts a greater understanding of smaller urban centres. In the process, it also interrogates the category of hill stations, which have been understood as exotic and scenic sites rather than as towns that were integral to the colonial economy. In arguing that hill stations, particularly Darjeeling, were not merely the scenic and healthy 'other' of the clamorous, dirty and diseased plains of India, it refutes suggestions that the 'despoiling' or overcrowding of Darjeeling was incremental to the purposes of its establishment. Instead, it suggests that Darjeeling was part of the colonial mainstream; its urbanization and inclusion into the greater colonial economy was effected from the time of its establishment. Therefore, a constant tension between its exotic and its functional elements persisted throughout.

The logic of location: malaria research in colonial India, Darjeeling and Duars,1900-30.

This article explores the scientific and entrepreneurial incentives for malaria research in the tea plantations of north Bengal in colonial India. In the process it highlights how the logic of 'location' emerged as the central trope through which medical experts, as well as colonial administrators and planters, defined malaria research in the region. The paper argues that the 'local' emerged as both a prerequisite of colonial governance as well as a significant component of malaria research in the field. Despite the ambiguities that such a project entailed, tropical medicine was enriched from a diverse understanding of local ecology, habitation, and structural modes of production. Nevertheless, the locality itself did not benefit from anti-malarial policy undertaken either by medical experts or the colonial state. This article suggests that there was a disjuncture between 'tropical medicine' and its 'field' that could not be accommodated within the colonial plantation system.

Nebulin interacts with CapZ and regulates thin filament architecture within the Z-disc.

The barbed ends of actin filaments in striated muscle are anchored within the Z-disc and capped by CapZ; this protein blocks actin polymerization and depolymerization in vitro. The mature lengths of the thin filaments are likely specified by the giant "molecular ruler" nebulin, which spans the length of the thin filament. Here, we report that CapZ specifically interacts with the C terminus of nebulin (modules 160-164) in blot overlay, solid-phase binding, tryptophan fluorescence, and SPOTs membrane assays. Binding of nebulin modules 160-164 to CapZ does not affect the ability of CapZ to cap actin filaments in vitro, consistent with our observation that neither of the two C-terminal actin binding regions of CapZ is necessary for its interaction with nebulin. Knockdown of nebulin in chick skeletal myotubes using small interfering RNA results in a reduction of assembled CapZ, and, strikingly, a loss of the uniform alignment of the barbed ends of the actin filaments. These data suggest that nebulin restricts the position of thin filament barbed ends to the Z-disc via a direct interaction with CapZ. We propose a novel molecular model of Z-disc architecture in which nebulin interacts with CapZ from a thin filament of an adjacent sarcomere, thus providing a structural link between sarcomeres.

Structure/function analysis of the interaction of phosphatidylinositol 4,5-bisphosphate with actin-capping protein: implications for how capping protein binds the actin filament.

The heterodimeric actin-capping protein (CP) can be inhibited by polyphosphoinositides, which may be important for actin polymerization at membranes in cells. Here, we have identified a conserved set of basic residues on the surface of CP that are important for the interaction with phosphatidylinositol 4,5-bisphosphate (PIP(2)). Computational docking studies predicted the identity of residues involved in this interaction, and functional and physical assays with site-directed mutants of CP confirmed the prediction. The PIP(2) binding site overlaps with the more important of the two known actin-binding sites of CP. Correspondingly, we observed that loss of PIP(2) binding correlated with loss of actin binding among the mutants. Using TIRF (total internal reflection fluorescence) microscopy, we observed that PIP(2) rapidly converted capped actin filaments to a growing state, consistent with uncapping. Together, these results extend our understanding of how CP binds to the barbed end of the actin filament, and they support the idea that CP can "wobble" when bound to the barbed end solely by the C-terminal "tentacle" of its beta-subunit.

Binding of myotrophin/V-1 to actin-capping protein: implications for how capping protein binds to the filament barbed end.

The heterodimeric actin-capping protein (CP) regulates actin assembly and cell motility by binding tightly to the barbed end of the actin filament. Here we demonstrate that myotrophin/V-1 binds directly to CP in a 1:1 molar ratio with a Kd of 10-50 nm. V-1 binding inhibited the ability of CP to cap the barbed ends of actin filaments. The actin-binding COOH-terminal region, the "tentacle," of the CP beta subunit was important for binding V-1, with lesser contributions from the alpha subunit COOH-terminal region and the body of the protein. V-1 appears to be unable to bind to CP that is on the barbed end, based on the observations that V-1 had no activity in an uncapping assay and that the V-1.CP complex had no capping activity. Two loops of V-1, which extend out from the alpha-helical backbone of this ankyrin repeat protein, were necessary for V-1 to bind CP. Parallel computational studies determined a bound conformation of the beta tentacle with V-1 that is consistent with these findings, and they offered insight into experimentally observed differences between the alpha1 and alpha2 isoforms as well as the mutant lacking the alpha tentacle. These results support and extend our "wobble" model for CP binding to the actin filament, in which the two COOH-terminal regions of CP bind independently to the actin filament, and bound CP is able to wobble when attached only via its mobile beta-subunit tentacle. This model is also supported by molecular dynamics simulations of CP reported here. The existence of the wobble state may be important for actin dynamics in cells.

Differential effects of phthalates on the testis and the liver.

Phthalates have been shown to elicit contrasting effects on the testis and the liver, causing testicular degeneration and promoting abnormal hepatocyte proliferation and carcinogenesis. In the present study, we compared the effects of phthalates on testicular and liver cells to better understand the mechanisms by which phthalates cause testicular degeneration. In vivo treatment of rats with di-(2-ethylhexyl) phthalate (DEHP) caused a threefold increase of germ cell apoptosis in the testis, whereas apoptosis was not changed significantly in livers from the same animals. Western blot analyses revealed that peroxisome proliferator-activated receptor (PPAR) alpha is equally abundant in the liver and the testis, whereas PPAR gamma and retinoic acid receptor (RAR) alpha are expressed more in the testis. To determine whether the principal metabolite of DEHP, mono-(2-ethylhexyl) phthalate (MEHP), or a strong peroxisome proliferator, 4-chloro-6(2,3-xylindino)-2-pyrimidinylthioacetic acid (Wy-14,643), have a differential effect in Sertoli and liver cells by altering the function of RAR alpha and PPARs, their nuclear trafficking patterns were compared in Sertoli and liver cells after treatment. Both MEHP and Wy-14,643 increased the nuclear localization of PPAR alpha and PPAR gamma in Sertoli cells, but they decreased the nuclear localization of RAR alpha, as previously shown. Both PPAR alpha and PPAR gamma were in the nucleus and cytoplasm of liver cells, but RAR alpha was predominant in the cytoplasm, regardless of the treatment. At the molecular level, MEHP and Wy-14,643 reduced the amount of phosphorylated mitogen-activated protein kinase (activated MAPK) in Sertoli cells. In comparison, both MEHP and Wy-14,643 increased phosphorylated MAPK in liver cells. These results suggest that phthalates may cause contrasting effects on the testis and the liver by differential activation of the MAPK pathway, RAR alpha, PPAR alpha, and PPAR gamma in these organs.

Peroxisome proliferators disrupt retinoic acid receptor alpha signaling in the testis.

Peroxisome proliferators include a diverse group of chemicals, some of which have been demonstrated to be testicular toxicants. However, the mechanism by which peroxisome proliferators, such as phthalates, cause testicular damage is not clear. It is known that retinoic acid receptor alpha (RARalpha) and its retinoic acid ligand, the acid form of vitamin A, are required for spermatogenesis. It has been demonstrated that the absence of RARalpha gene or vitamin A in the animal leads to testis degeneration and sterility. Therefore, any compound that disrupts the action of vitamin A in the testis could potentially be damaging to male fertility. The current investigation examined a novel hypothesis that a mechanism of degeneration by peroxisome proliferators in the testis is due, in part, to disruption of the critical RARalpha signaling pathway. We show that peroxisome proliferators were able to disrupt the retinoic acid-induced nuclear localization of RARalpha and the retinoic acid-stimulated increase in transcriptional activity of a retinoic acid-responsive reporter gene in Sertoli cells. Concomitantly, peroxisome proliferators increased the nuclear localization of PPARalpha and the transcriptional activity of a peroxisome proliferator-responsive reporter gene in these cells. These results indicate that peroxisome proliferators can indeed shift the balance of nuclear localization for RARalpha and PPARalpha, resulting in deactivation of the critical RARalpha transcriptional activity in Sertoli cells.

Phosphorylation of the cell cycle inhibitor p21Cip1/WAF1 by Pim-1 kinase.

The serine/threonine kinase, Pim-1, appears to be involved in regulating proliferation, differentiation and cell survival of lymphoid and myeloid cells. In this study, we have found that amino acid residues 140-147 (RKRRQTSM) at the C-terminal end of p21(Cip1/WAF1), a cyclin-dependent kinase (CDK) inhibitor, constitute an ideal phosphorylation consensus sequence for Pim-1. We demonstrate that Pim-1 efficiently phosphorylates this peptide sequence as well as the p21 protein in vitro. We also demonstrate by pull-down assay and by immunoprecipitation that Pim-1 associates with p21. During phorbol ester-induced differentiation of U937 cells, both Pim-1 and p21 expression levels increase with Pim-1 levels increasing in both the nucleus and cytoplasm while p21 remains primarily cytoplasmic. Co-transfection of wild type p21 with wild type Pim-1 results in cytoplasmic localization of p21 while co-transfection of wild type p21 with kinase dead Pim-1 results in nuclear localization of p21. Consistent with the results from the phosphoamino acid assay, Pim-1 phosphorylates transfected p21 only on Thr(145) in p21-deficient human fibroblasts and this phosphorylation event results in the cytoplasmic localization of p21. These findings demonstrate that Pim-1 associates with and phosphorylates p21 in vivo, which influences the subcellular localization of p21.

Pim-1 associates with protein complexes necessary for mitosis.

The proto-oncogene pim-1 is a serine/threonine kinase the over-expression of which promotes lymphoma formation. Neither the normal function of Pim-1 nor the biochemical mechanism for cancer development mediated by the gene has been delineated, although recent studies have provided compelling evidence that Pim-1 is involved in differentiation and cell survival. We now provide the first evidence that Pim-1 may be involved in the proliferative process. By confocal microscopy, we observed a dynamic redistribution of Pim-1 during the cell cycle, the protein moving from the nucleus and cytoplasm in interphase to the spindle poles during mitosis. From a computer search for putative substrates of Pim-1 that are located in the spindle poles, we discovered that the nuclear mitotic apparatus (NuMA) protein has two peptide sequences that contain preferred phosphorylation sites for Pim-1 kinase. Recombinant glutathione-S-transferase-Pim-1 also readily phosphorylates immunoprecipitated NuMA. By confocal microscopy and co-immunoprecipitation we showed the interaction of the Pim-1 and NuMA proteins in HeLa cells that had been arrested during mitosis with nocodazole. Pim-1 also appeared to interact with heterochromatin-associated protein 1beta (HP1beta) and the cytoplasmic proteins dynein and dynactin via complex formation with NuMA. In our studies, overexpressed wild-type-Pim-1-GFP (green fluorescent protein) fusion protein was found to co-localize in the spindle pole with NuMA during mitosis. In contrast, the 'kinase-dead' mut-Pim-1-GFP fusion protein did not co-localize with NuMA, and appeared to promote apoptosis. Further evidence for apoptotic cell death was the observed blebbing and fragmentation of the chromosomes and a decrease in the level of NuMA protein detected by confocal microscopy. These results strongly suggest that Pim-1 kinase plays a role, most likely by phosphorylation, in promoting complex formation between NuMA, HP1beta, dynein and dynactin, a complex that is necessary for mitosis.