High-resolution cell imaging using white light phase shifting interferometry and iterative phase deconvolution.

An optimization algorithm is presented for the deconvolution of a complex field to improve the resolution and accuracy of quantitative phase imaging (QPI). A high-resolution phase map can be recovered by solving a constrained optimization problem of deconvolution using a complex gradient operator. The method is demonstrated on phase measurements of samples using a white light based phase shifting interferometry (WLPSI) method. The application of the algorithm on real and simulated objects shows a significant resolution and contrast improvement. Experiments performed on Escherichia coli bacterium have revealed its sub-cellular structures that were not visible in the raw WLPSI images obtained using a five phase shifting method. These features can give valuable insights into the structures and functioning of biological cells. The algorithm is simple in implementation and can be incorporated into other QPI modalities .

Effect of stroke plane inclination on the hovering aerodynamic performance of tandem flapping foils.

The four-winged form of dragonfly and damselfly allows them to fly with great agility and endurance, which are accomplished by independently controlling the kinematics of each wing. In this study, we performed numerical simulations of two tandem airfoils oscillating along an inclined stroke plane atRe=157. We investigated the effects of the stroke plane angle (ß)of forefoil and hindfoil on the aerodynamic performance of dragonflies (or damselflies) hovering flight. Simulations were conducted for parallel and non-parallel stroke planes of forefoil and hindfoil oscillating with three phase differences:ϕ=0o,90oand180o. For parallel stroke planes, the results show that the total lift increases withß, whereas the total thrust decreases in same condition. In addition, the total lift and thrust decrease with an increase inϕ. The forefoil performance is affected by the flow induced by hindfoil's leading-edge vortices, and the hindfoil interactions with forefoil's wake vortices significantly affect the hindfoil's performance. The findings demonstrate that non-parallel stroke planes exert detrimental effects on the total lift forϕ=0oand90o. However, forϕ=180o, the lift augmentation of 46% is obtained in the case where the forefoil stroke plane angle is smaller than the hindfoil. The results obtained during this investigation can help in optimizing the wing kinematics during the micro air vehicles development.

Dibenzi Heteroheptaphyrin(2.0.1.1.1.1.0)s: Synthesis, Spectral, Redox and Theoretical Studies.

Three examples of dibenzi heteroheptaphyrin(2.0.1.1.1.1.0)s were synthesized by condensing bis(phenylene ethene) based hexapyrrane with appropriate diol, 2,5-bis(α-hydroxy-α-arylmethyl) thiophene or selenophene in CH2 Cl2 under BF3 ⋅ OEt2 catalyzed inert atmosphere conditions followed by DDQ oxidation in open air. HR-MS analyses confirmed the identities of dibenzi heteroheptaphyrins. The DFT optimized structures revealed that dibenzi heteroheptaphyrins were highly distorted nonplanar macrocycles with two thiophene rings preferred to be in an inverted conformation. 1D & 2D NMR helped in deducing the molecular structures of dibenzi heteroheptaphyrins and supported their nonaromatic nature. The theoretical NMR calculations were carried which matched closely with the experimental NMR data. NMR studies also revealed that the π-delocaliztion was significantly altered in dibenzi heteroheptaphyrins compared to previously reported dibenzi hexaphyrins. The dibenzi heptaphyrins showed one sharp absorption band in 400-500 nm region and a broad band in the region of 600-800 nm which were bathochromically shifted in their diprotonated derivatives. The theoretical absorption calculations corroborate the slight hypsochromic shift of the broad absorption band in the lower energy region of dibenzi heptaphyrins compared to dibenzi hexaphyrins. The electrochemical studies revealed that the dibenzi heptaphyrins were easier to reduce but difficult to oxidize compared to dibenzi hexaphyrins.

Assessment of managed aquifer recharge in saline confined aquifers for freshwater storage and improved recovery: A 3D tank study under various operational conditions.

Aquifer Storage and Recovery (ASR), a subset of Managed Aquifer Recharge (MAR) techniques, is a promising technique to address water scarcity issues by recharging depleted aquifers. The application of ASR in saline groundwater regions is challenging due to mixing of recharged freshwater with the ambient saline groundwater, decreasing the recoverable amount of freshwater. This paper aimed to investigate the feasibility of ASR techniques for freshwater storage and recovery in saline confined aquifers using a laboratory scale physical model (100 cm length x 30 cm width x 60 cm depth). The study then explored the impact of operational factors (freshwater storage duration, injected freshwater volume, number of injection/extraction cycles etc.) on freshwater recovery from an applied ASR. Firstly, the behaviour of stored freshwater in a saline-confined aquifer was investigated, and in the next step, the impact of ASR operational parameters on the recovery efficiency (RE) was evaluated. Along with the physical model, these effects were studied using a mathematical model (MODFLOW linked with SEAWAT) for the representative aquifer system. The movement and spreading of the stored freshwater were monitored over time. The experimental results presented in this study suggested that several factors significantly influence the efficiency of ASR systems. A negative correlation between ambient groundwater salinity and average recovery efficiency (ARE) was confirmed, with decreasing ARE observed as the salinity level increased. The injection volume of freshwater was found to have a positive influence on ARE, although the relationship was non-linear, a polynomial trend was observed. The longer freshwater was stored in the aquifer, the lower ARE was reported, indicating a negative impact of storage duration on ASR performance. Finally, the number of successive cycles of ASR operation was found to have a positive influence on ARE, but the effect decreased with each subsequent cycle. This research provided valuable insights into the application of ASR techniques for freshwater storage and its enhanced recovery in saline confined aquifers.

Nucleophilic sulfur controlled efficient ketothioamide synthesis from tribromomethyl carbinols.

A mild, catalyst and oxidant-free efficient protocol for synthesizing α-ketothioamides is reported with a broad substrate scope. The presented protocol demonstrates the confined reactivity of amines. The polysulfide derived from elemental sulfur and amines in an aqueous medium drives the pathway toward diverse α-ketothioamides over thioamides. Substrates with different substituent groups were compatible with the presented protocol, and the respective ketothioamides were separated in good to excellent yields. The ketothioamides, known to exhibit anti-cancer properties, were synthesized by the proposed protocol. Furthermore, the synthetic utility was explored with the typical synthesis of ketoamides.

Synthesis, Spectral, Redox and Theoretical Studies of Stable Nonaromatic Dicarba Dithia Hexaphyrin(2.0.1.1.1.0)s with Two Inverted Thiophenes.

A series of dicarba dithia hexaphyrin(2.0.1.1.1.0)s containing two p-phenylene rings, two thiophene rings, and two pyrrole rings connected via five meso carbons were synthesized by condensing the key precursor, hexapyrrane, which was prepared over a sequence of steps, with the appropriate aromatic aldehyde under acid catalytic conditions followed by alumina chromatographic purification. Detailed one-dimensional (1D) and two-dimensional (2D) NMR studies revealed that the two thiophene rings were inverted and facing outward from the macrocyclic core. Interestingly, one of the inverted thiophene rings adopts a normal orientation in the protonated derivatives of macrocycles generated by addition of trifluoroacetic acid to the appropriate macrocyclic solution. The spectroscopic studies support the non-aromatic nature of macrocycles, and the macrocycles exhibit a distinct sharp band at ∼425 nm along with a broad band in the range of 550-1000 nm, which experienced a red shift with a clear color change in the protonated derivatives. The redox studies showed lower oxidation potentials, indicating their electron-rich nature. The density functional theoretical (DFT) studies showed that the hexaphyrins adopt oval-shaped structures, and time-dependent-DFT (TD-DFT) studies parallelly matched the experimental observations of macrocycles.

Vinca alkaloids as a potential cancer therapeutics: recent update and future challenges.

Vinca alkaloids including vincristine, vinblastine, vindesine, and vinflunine are chemotherapeutic compounds commonly used to treat various cancers. Vinca alkaloids are one of the first microtubule-targeting agents to be produced and certified for the treatment of hematological and lymphatic neoplasms. Microtubule targeting agents like vincristine and vinblastine work by disrupting microtubule dynamics, causing mitotic arrest and cell death. The key issues facing vinca alkaloids applications include establishing an environment-friendly production technique based on microorganisms, as well as increasing bioavailability without causing harm to patient's health. The low yield of these vinca alkaloids from the plant and the difficulty of meeting their huge colossal demand around the globe prompted researchers to create a variety of approaches. Endophytes could thus be selected to produce beneficial secondary metabolites required for the biosynthesis of vinca alkaloids. This review covers the significant aspects of these vital drugs, from their discovery to the present day, in a concise manner. In addition, we emphasize the major hurdles that must be overcome in the coming years to improve vinca alkaloid's effectiveness.

Label-free high-resolution white light quantitative phase nanoscopy system.

We present a high-resolution white light quantitative phase nanoscopy (WLQPN) system that can be utilized to visualize nanoparticles and subcellular features of the biological specimens. The five-phase shifting technique, along with deconvolution, is adopted to obtain super-resolution in phase imaging. The phase shifting technique can provide full detector resolution, making it beneficial as compared to the well-known Fourier analysis method. The Fourier transform method requires minimum angle of sin - 1 3 f x λ , where f x is maximum achievable spatial frequency. It limits the highest achievable resolution to much below the actual diffraction limit of the system. Thus, to obtain a high-resolution phase map of the biological specimen, a two-step process is adopted. First, the phase map is recovered using the five-phase shifting algorithm, with full detector spatial resolution. Second, the complex field is obtained from the recovered phase map and further processed using the Richardson Lucy total variation deconvolution algorithm to obtain super-resolution phase images. The present technique was tested on 1951 USAF resolution chart, 200 nm polystyrene beads and Escherichia coli bacteria using a 50×, 0.55NA objective lens. The 200 nm polystyrene beads are visually resolvable and subcellular features of the E. coli bacteria are also observed, suggesting a significant improvement in the resolution.

First activity and interactions in thalamus and cortex using raw single-trial EEG and MEG elicited by somatosensory stimulation.

Introduction: One of the primary motivations for studying the human brain is to comprehend how external sensory input is processed and ultimately perceived by the brain. A good understanding of these processes can promote the identification of biomarkers for the diagnosis of various neurological disorders; it can also provide ways of evaluating therapeutic techniques. In this work, we seek the minimal requirements for identifying key stages of activity in the brain elicited by median nerve stimulation. Methods: We have used a priori knowledge and applied a simple, linear, spatial filter on the electroencephalography and magnetoencephalography signals to identify the early responses in the thalamus and cortex evoked by short electrical stimulation of the median nerve at the wrist. The spatial filter is defined first from the average EEG and MEG signals and then refined using consistency selection rules across ST. The refined spatial filter is then applied to extract the timecourses of each ST in each targeted generator. These ST timecourses are studied through clustering to quantify the ST variability. The nature of ST connectivity between thalamic and cortical generators is then studied within each identified cluster using linear and non-linear algorithms with time delays to extract linked and directional activities. A novel combination of linear and non-linear methods provides in addition discrimination of influences as excitatory or inhibitory. Results: Our method identifies two key aspects of the evoked response. Firstly, the early onset of activity in the thalamus and the somatosensory cortex, known as the P14 and P20 in EEG and the second M20 for MEG. Secondly, good estimates are obtained for the early timecourse of activity from these two areas. The results confirm the existence of variability in ST brain activations and reveal distinct and novel patterns of connectivity in different clusters. Discussion: It has been demonstrated that we can extract new insights into stimulus processing without the use of computationally costly source reconstruction techniques which require assumptions and detailed modeling of the brain. Our methodology, thanks to its simplicity and minimal computational requirements, has the potential for real-time applications such as in neurofeedback systems and brain-computer interfaces.

Doubly Fused Unsymmetrical Calixdicarbahexaphyrins.

Three novel doubly fused unsymmetrical calixdicarbahexaphyrins were synthesized by mild acid-catalyzed (4+2) condensation of dicarbatetrapyrrane with dipyrroethene diol followed by oxidation. The condensation formed doubly fused calixdicarbahexaphyrins instead of π-conjugated dicarbahexaphyrins, due to the unusual fusion of the pyrrole N with the α-carbon of the adjacent pyrrole ring to form a tripentacyclic ring and one usual fusion of the pyrrole N with the adjacent phenylene C to form a fused moiety containing two pentacycles and one hexacycle ring. Both fusions occurred on one side of the macrocycle, making the macrocycles unsymmetric. The crystal structure obtained for one of the macrocycles exhibited a saddle-shaped structure with two benzene rings and four pyrrole rings connected via two ethylene and four methene meso-carbon atoms. The crystal structure also revealed unusual fusions in the macrocyclic framework and the presence of one sp3 carbon that disrupts the π-electron delocalization. 1H, 1H-1H COSY, NOESY, 13C, and HMBC NMR techniques were used to characterize the macrocycles. The absorption spectra of the macrocycles showed one intense sharp band at ∼485 nm along with a shoulder in the lower-energy region, suggesting its non-aromatic nature. Electrochemical studies indicated their electron rich nature, and DFT/TD-DFT studies corroborated the experimental observations.

Two classes of functional connectivity in dynamical processes in networks.

The relationship between network structure and dynamics is one of the most extensively investigated problems in the theory of complex systems of recent years. Understanding this relationship is of relevance to a range of disciplines-from neuroscience to geomorphology. A major strategy of investigating this relationship is the quantitative comparison of a representation of network architecture (structural connectivity, SC) with a (network) representation of the dynamics (functional connectivity, FC). Here, we show that one can distinguish two classes of functional connectivity-one based on simultaneous activity (co-activity) of nodes, the other based on sequential activity of nodes. We delineate these two classes in different categories of dynamical processes-excitations, regular and chaotic oscillators-and provide examples for SC/FC correlations of both classes in each of these models. We expand the theoretical view of the SC/FC relationships, with conceptual instances of the SC and the two classes of FC for various application scenarios in geomorphology, ecology, systems biology, neuroscience and socio-ecological systems. Seeing the organisation of dynamical processes in a network either as governed by co-activity or by sequential activity allows us to bring some order in the myriad of observations relating structure and function of complex networks.

Fabrication of low cost highly structured silver capped aluminium nanorods as SERS substrate for the detection of biological pathogens.

We report the fabrication of low cost highly structured silver (Ag) capped aluminium (Al) nanorods (NRs) as surface enhanced Raman spectroscopy (SERS) substrate utilising the glancing angle deposition technique. The nano-capping of silver onto the Al NRs can concentrate the local electric field within the minimal volume that can serve as hotspots. The average size of the Ag nanocaps was 50 nm. The newly proposed nanoporous Ag capped Al NRs as SERS substrate could detect the Raman signal of rhodamine 6G (R6G) up to 10-15molar concentration. The significant enhancement in the Raman signal of 107was achieved for Ag capped Al NRs considering R6G as a probe molecule. Using the developed SERS substrate, we recorded Raman spectra forEscherichia colibacteria with its concentration varying from 108colony forming units per ml (CFU ml-1) up to 102CFU ml-1. All the reported Raman spectra were acquired by a portable handheld Raman spectrometer. Hence, this newly proposed low cost, effective SERS substrate can be used commercially for the onsite detection of clinical pathogens. The 3D finite difference time domain simulation model was performed for Ag capped Al nanostructure to understand the generation of hotspots. The simulated results show excellent agreement with the experimental results. We fabricated uncapped Ag nanorods of similar dimensions and performed the experimental measurements and simulations for comparison. We found a significant enhancement in Ag capped Al NRs compared to the long Ag NRs. The description of the Raman signal enhancement has been elaborated.

Quantification of node importance in rain gauge network: influence of temporal resolution and rain gauge density.

Rain gauge network is important for collecting rainfall information effectively and efficiently. Rain gauge networks have been studied for several decades from a range of hydrological perspectives, where rain gauges with unique or non-repeating information are considered as important. However, the problem of quantification of node importance and subsequent identification of the most important nodes in rain gauge networks have not yet been extensively addressed in the literature. In this study, we use the concept of the complex networks to evaluate the Indian Meteorological Department (IMD) monitored 692 rain gauge in the Ganga River Basin. We consider the complex network theory-based Degree Centrality (DC), Clustering Coefficient (CC) and Mutual Information (MI) as the parameters to quantify the rainfall variability associated with all the rain gauges in the network. Multiple rain gauge network scenario with varying rain gauge density (i.e. Network Size (NS) = 173, 344, 519, and 692) and Temporal Resolution (i.e. TR = 3 hours, 1 day, and 1 month) are introduced to study the effect of rain gauge density, gauge location and temporal resolution on the node importance quantification. Proxy validation of the methodology was done using a hydrological model. Our results indicate that the network density and temporal resolution strongly influence a node's importance in rain gauge network. In addition, we concluded that the degree centrality along with clustering coefficient is the preferred parameter than the mutual information for the node importance quantification. Furthermore, we observed that the network properties (spatial distribution, DC, Collapse Correlation Threshold (CCT), CC Range distributions) associated with TR = 3 hours and 1 day are comparable whereas TR = 1 month exhibit completely different trends. We also found that the rain gauges situated at high elevated areas are extremely important irrespective of the NS and TR. The encouraging results for the quantification of nodes importance in this study seem to indicate that the approach has the potential to be used in extreme rainfall forecasting, in studying changing rainfall patterns and in filling gaps in spatial data. The technique can be further helpful in the ground-based observation network design of a wide range of meteorological parameters with spatial correlation.

Aerobic granular sludge and naphthenic acids treatment by varying initial concentrations and supplemental carbon concentrations.

Aerobic granular sludge (AGS) has previously been utilized in the treatment of toxic compounds due to its diverse and dense microbial structure. The present study subjected mature AGS to model naphthenic acids (NAs) representative of the Canadian oil sands. To this effect, three NA concentrations (10, 50 and 100 mg/L) and three supplemental carbon source concentrations (600, 1200 and 2500 mg/L) were studied in batch reactors for 5 days. The responding variables were chemical oxygen demand (COD), NA concentrations and nutrients. Cyclohexane carboxylic acid (CHCA), cyclohexane acetic acid (CHAA) and 1-adamantane carboxylic acid (ACA) were chosen to study structure-based degradation kinetics. The optimal COD according to the runs was 1200 mg/L. CHCA was removed completely with biodegradation rate constants increasing with lower NA concentrations and lower COD concentrations. CHAA was also removed completely, however, an optimal rate constant of 1.9 d-1 was achieved at NA and COD concentrations of 50 mg/L and 1200 mg/L, respectively. ACA removal trends did not follow statistically significant regressions; however, degradation and sorption helped remove ACA up to 19.9%. Pseudomonas, Acinetobacter, Hyphomonas and Brevundimonas spp. increased over time, indicating increased AGS adaptability to NAs.