Photomechanical Crystals as Light-Activated Organic Soft Microrobots.

In the field of materials science, dynamic molecular crystals have attracted significant attention as a novel class of energy-transducing materials. However, their development into becoming fully functional actuators remains somewhat limited. This study focuses on one family of dynamic crystalline materials and delves into exploring the efficiency of conversion of light energy to mechanical work. A simple setup is designed to determine a set of performance indices of anthracene-based crystals as an exemplary class of dynamic molecular crystals. The ability of these crystals to reversibly bend due to dimerization is realistically assessed from the perspective of the envisaged soft robotics applications, where wireless photomechanical grippers manipulate and assemble microscopic objects driven and controlled by light instead of lines and motors. The approach described here not only guides the quantification of responsive molecular crystals' actuation potential but also aims to attract an interdisciplinary interest to further develop this class of materials into controllable all-organic actuating elements to be used in microrobotics for engineering or biomedicine.

Maternal and fetal outcomes in pregnancy complicated by pre-existing lupus nephritis: Insights from a developing country Pakistan.

BACKGROUND: Pregnancy in women with systemic lupus erythematosus (SLE) has remained a great challenge for clinicians in terms of maternal and fetal outcomes. The outcomes in women with pre-existing lupus nephritis (LN) are variable. The impact of different classes of LN on maternal and fetal outcomes during pregnancy is not well defined, as data is very scarce, especially from the developing countries. METHODS: A retrospective analysis was conducted on 52 women with 89 pregnancies. All had biopsy-proven LN. Those women who conceived at least 6 months after the diagnosis were included. The analysis was conducted between July 1998 and June 2018 at Sindh Institute of Urology and Transplantation (SIUT), evaluating the outcomes for both the mother and the fetus with a minimum follow-up of 12 months after child birth. RESULTS: The mean maternal age at SLE diagnosis was 21.45 ± 6 years and at first pregnancy was 26.49 ± 5.63 years. The mean disease duration was 14.02 ± 19.8 months. At conception, 47 (52.8%) women were hypertensive, 9 (10%) had active disease while 38 (42.7%) and 42 (47.2%) were in complete and partial remission, respectively. A total of 17 (19.1%) were on mycophenolate mofetil (MMF), which was switched to azathioprine (AZA). Out of 89 pregnancies, 56 (62.9%) were successful, while 33 (37.07%) had fetal complications like spontaneous abortion, stillbirth, perinatal death, and intrauterine growth retardation (IUGR). There were more vaginal deliveries (33 [58.92%]) than caesarean sections (23 [41.07%]). Renal flare was observed in 33 (37.1%) women while 15 (16.9%) developed pre-eclampsia. Proliferative LN was found in 56 (62.9%) cases, but no significant differences were found in maternal and fetal outcomes in relation to LN classes (p = .58). However, disease outcomes at 12 months were significantly poor in those with active disease at the time of conception (p < .05). There was only one maternal death. A total of 10 (11.2%) women showed deterioration in renal function and 5 (5.6%) were dialysis-dependent at 12 months. CONCLUSION: The maternal and fetal outcomes in pre-existing LN depend on the disease activity at the time of conception. No correlation was found between International Society of Nephrology/Renal Pathology Society (ISN/RPS) classes of LN and adverse disease and pregnancy outcomes.

Performance of molecular crystals in conversion of light to mechanical work.

Dynamic molecular crystals have recently received ample attention as an emerging class of energy-transducing materials, yet have fallen short of developing into fully realized actuators. Through the trans-cis surface isomerization of three crystalline azobenzene materials, here, we set out to extensively characterize the light-to-work energy conversion of photoinduced bending in molecular crystals. We distinguish the azobenzene single crystals from commonly used actuators through quantitative performance evaluation and specific performance indices. Bending molecular crystals have an operating range comparable to that of microactuators such as microelectromechanical systems and a work-generating capacity and dynamic performance that qualifies them to substitute micromotor drivers in mechanical positioning and microgripping tasks. Finite element modeling, applied to determine the surface photoisomerization parameters, allowed for predicting and optimizing the mechanical response of these materials. Utilizing mechanical characterization and numerical simulation tools proves essential in accelerating the introduction of dynamic molecular crystals into soft microrobotics applications.

Chemical Profile, Antibacterial Activity and Antioxidant Activity of Bark Volatile Oil of Terminalia arjuna.

Terminalia arjuna is an evergreen medicinal plant that belongs to the Combretaceae family of flowering plants. The bark of the plant exhibits antiviral, anticancer, hypocholesterolemic, antioxidant and antimicrobial properties. In this study, composition antibacterial activity, antioxidant activity and cytotoxicity of bark oil of Terminalia arjuna(Roxb.) were reported. Oils were extracted by microwave assisted hydrodistillation where an oil yield of 0.18 % was obtained followed by the identification of 35 compounds by gas chromatography mass spectrometry. The most abundant volatiles were furfural (11.11 %), isoeugenol (9.99 %), p-ethylguaiacol (9.97 %), α-cadinol (9.57 %), and estragole (9.47 %). The oil was further evaluated against ten different drug resistant strains where oil showed significant activity against all pathogens and the highest activity was found against Acinetobacter baumannii(22 mm), Klebsiella pneumoniae (22 mm) and Staphylococcus aureus(22 mm) in a concentration-dependent manner. Antioxidant activity evaluation demonstrated 68 % radical scavenging activity by the volatile oil as compared to 81 % of the standard, ascorbic acid at a concentration of 1000 µg. Cytotoxicity studies were conducted to see the effect of sample on the expression level of a housekeeping gene, Glyceraldehyde 3-phosphate dehydrogenase where it did not affect the normal transcription of the gene.

Modulating Optoelectronic and Elastic Properties of Anatase TiO2 for Photoelectrochemical Water Splitting.

Titanium dioxide (TiO2) has been investigated for solar-energy-driven photoelectrical water splitting due to its suitable band gap, abundance, cost savings, environmental friendliness, and chemical stability. However, its poor conductivity, weak light absorption, and large indirect bandgap (3.2 eV) has limited its application in water splitting. In this study, we precisely targeted these limitations using first-principle techniques. TiO2 only absorbs near-ultraviolet radiation; therefore, the substitution (2.1%) of Ag, Fe, and Co in TiO2 significantly altered its physical properties and shifted the bandgap from the ultraviolet to the visible region. Cobalt (Co) substitution in TiO2 resulted in high absorption and photoconductivity and a low bandgap energy suitable for the reduction in water without the need for external energy. The calculated elastic properties of Co-doped TiO2 indicate the ductile nature of the material with a strong average bond strength. Co-doped TiO2 exhibited fewer microcracks with a mechanically stable composition.

Elastic Organic Crystals as Bioinspired Hair-Like Sensors.

One of the typical haptic elements are natural hairy structures that animals and plants rely on for feedback. Although these hair sensors are an admirable inspiration, the development of active flow sensing components having low elastic moduli and high aspect ratios remains a challenge. Here, we report a new sensing approach based on a flexible, thin and optically transmissive organic crystal of high aspect ratio, which is stamped with fluorescent dye for tracking. When subjected to gas flow and exposed to laser, the crystal bends due to exerted pressure and acts as an optical flow (hair) sensor with low detection limit (≈1.578 m s-1 ) and fast response time (≈2.70 s). The air-flow-induced crystal deformation and flow dynamics response are modelled by finite element analysis. Due to having a simple design and being lightweight and mechanically robust this prototypical crystal hair-like sensor opens prospects for a new class of sensing devices ranging from wearable electronics to aeronautics.

Relating Excited States to the Dynamics of Macroscopic Strain in Photoresponsive Crystals.

Exposure of a photoreactive single crystal to light with a wavelength offset from its absorption maximum can have two distinct effects. The first is the "direct" effect, wherein the excited state generated in individual chemical species is influenced. The second is the "indirect" effect, which describes the penetration of light into the crystal and hence the spatial propagation and completeness of transformation. We illustrate using the nitro-nitrito isomerization of [Co(NH3)5NO2]Cl(NO3) as an example that the direct and indirect effects can be independently determined. This is achieved by comparing the dynamics of macroscopic crystal deformation (bending curvature and crystal elongation) induced by the photochemical reaction when irradiating a crystal at the absorption maximum and at different band edges (above or below the maximum) of the same band. Quantitative description of the macroscopic strain dynamics in comparison with experiments allowed us to suggest that irradiation at different tails of the same absorption band causes isomerization to proceed via different excited states and an additional photochemical reaction (presumably, reverse nitrito-nitro isomerization) can occur on irradiation at the ligand-field band edges.

Global Analysis of the Mechanical Properties of Organic Crystals.

Organic crystals, although widely studied, have not been considered nascent candidate materials in engineering design. Here we summarize the mechanical properties of organic crystals that have been reported over the past three decades, and we establish a global mechanical property profile that can be used to predict and identify mechanically robust organic crystals. Being composed of light elements, organic crystals populate a narrow region in the mechanical property-density space between soft, disordered organic materials and stiff, ordered materials. Two subsets of extraordinarily stiff and hard organic crystalline materials were identified and rationalized by the normalized number density, strength, and directionality of their intermolecular interactions. We conclude that future lightweight, soft, all-organic components in devices should capitalize on the greatest asset of organic single crystals-namely, the combination of long-range structural order and softness.

Multifunctional Deformable Organic Semiconductor Single Crystals.

We report the first organic semiconductor crystal with a unique combination of properties that can be used as a multifunctional optoelectronic device. Mechanically flexible single crystals of 9,10-bis(phenylethynyl)anthracene (BPEA) can function as a phototransistor, photoswitch, and an optical waveguide. The material can exist as two structurally different solid phases, with single crystals of one of the phases being elastic at room temperature while those of the other are brittle and become plastic at higher temperature. The output and transfer characteristics of the devices were characterized by measuring the generation and temporal response of the switching of the photogenerated current. The current-voltage characteristics of both phases exhibit linearity and symmetry about the positive and negative voltages. The crystals transmit light in the telecommunications range with significantly low optical loss for an organic crystalline material.

From Mechanical Effects to Mechanochemistry: Softening and Depression of the Melting Point of Deformed Plastic Crystals.

The melting of any pure crystalline material at constant pressure is one of its most fundamental properties, and it has been used to identify organic compounds or to verify their chemical or phase purity since the early times of chemistry. Here, we report that a mechanical deformation of plastic organic single crystals such as bending results in a small yet significant decrease in their melting point of about 0.3-0.4 K. The bent section of the crystal was found to be mechanically softer relative to the straight sections, and the softening temperature preceding the melting was also lower on the convex (outer) side of the bent crystal. Melting of the bent crystal starts at the kink and often appears as splitting of the respective endothermic peak in its thermal (DSC) fingerprint, while unilateral compression of the crystal results in multiple peaks. These thermomechanical effects become more pronounced with heavier mechanical damage due to an increased concentration of defects and ultimately result in a large temperature spread of the associated phase change in addition to melting-point depression in deformed or damaged crystals relative to their pristine counterparts. Within a broader context, the results show that mechanical treatment during sample preparation has a profound effect on the melting of a pure substance, and this could be critically important where the exact melting point is used as a means for polymorph identification.

The Rise of the Dynamic Crystals.

The anticipated shift in the focal point of interest of solid-state chemists, crystal engineers, and crystallographers from structure to properties to function parallels the need to apply our accumulated understanding of the intricacies of crystal structure to explaining the related properties, with the ultimate goal of harnessing that knowledge in applications that require soft, lightweight, or biocompatible organic solids. In these developments, the adaptive molecular crystals warrant particular attention as an alternative choice of materials for light, flexible, and environmentally benign devices, primarily memories, capacitors, sensors, and actuators. Some of the outstanding requirements for the application of these dynamic materials as high-efficiency energy-storage devices are strongly induced polarization, a high switching field, and narrow hysteresis in the case of reversible dynamic processes. However, having been studied almost exclusively by chemists, molecular crystals still lack the appropriate investigations that reliably evaluate their reproducibility, scalability, and actuating performance, and some important drawbacks have diverted the interest of engineers from these materials in applications. United under the umbrella term crystal adaptronics, the recent research efforts aim to realistically assess the appositeness of dynamic crystals for applications that require fast, reversible, and continuous operation over prolonged periods of time. With the aim of highlighting the most recent developments, this Perspective discusses their assets and pitfalls. It also provides some hints on the likely future developments that capitalize on the untapped, sequestered potential of this distinct materials class for applications.

Pyrolysis of polystyrene waste for recovery of combustible hydrocarbons using copper oxide as catalyst.

The present work is focused on pyrolysis of polystyrene waste for production of combustible hydrocarbons. The experiments were performed in an indigenously made furnace in the presence of a laboratory synthesised copper oxide. The pyrolysis products were collected and characterised. The Fourier transform infrared spectra showed that the liquid fraction contains C-H, C-O, C-C, C=C and O-H bonds, which correspond to various aliphatic and aromatic compounds. Gas chromatography-mass spectrometry traced compounds ranging from C1 to C4 in the gaseous fraction, whereas in the liquid fraction 15 components ranging from C3 to C24 were detected. From the results it has been concluded that CuO as a catalyst not only increased the liquid yield but also reduced the degradation temperature to great extent. Fuel properties of the pyrolysis oil were determined and compared with standard values of commercial fuel oil. The comparison suggested potential application of pyrolysis oil for domestic and commercial use.

Micromanipulation of Mechanically Compliant Organic Single-Crystal Optical Microwaveguides.

Flexible organic single crystals are evolving as new materials for optical waveguides that can be used for transfer of information in organic optoelectronic microcircuits. Integration in microelectronics of such crystalline waveguides requires downsizing and precise spatial control over their shape and size at the microscale, however that currently is not possible due to difficulties with manipulation of these small, brittle objects that are prone to cracking and disintegration. Here we demonstrate that atomic force microscopy (AFM) can be used to reshape, resize and relocate single-crystal microwaveguides in order to attain spatial control over their light output. Using an AFM cantilever tip, mechanically compliant acicular microcrystals of three N-benzylideneanilines were bent to an arbitrary angle, sliced out from a bundle into individual crystals, cut into shorter crystals of arbitrary length, and moved across and above a solid surface. When excited by using laser light, such bent microcrystals act as active optical microwaveguides that transduce their fluorescence, with the total intensity of transduced light being dependent on the optical path length. This micromanipulation of the crystal waveguides using AFM is non-invasive, and after bending their emissive spectral output remains unaltered. The approach reported here effectively overcomes the difficulties that are commonly encountered with reshaping and positioning of small delicate objects (the "thick fingers" problem), and can be applied to mechanically reconfigure organic optical waveguides in order to attain spatial control over their output in two and three dimensions in optical microcircuits.

Spatial Photocontrol of the Optical Output from an Organic Crystal Waveguide.

The versatility in mechanical properties and the capability of optical waveguiding of molecular crystals have attracted research on the potential application of these materials in optomechanical transduction. Here, we demonstrate spatial photocontrol over the optical output from slender single crystals of an azo compound, 3',4'-dimethyl-4-(dimethylamino)azobenzene that can be used as a crystalline optical waveguide. The position of the free end of a single crystal can be controlled through reversible photoswitching between the trans and cis isomers at the irradiated crystal surface. The passive optical waveguiding capability of the crystal remains unaffected by its deformation induced by exposure to UV light. Moreover, the response time of the material by bending upon irradiation can be thermally regulated to control the positioning of the tip of the crystal. These single-crystal organic actuators with dual (optical and photomechanical) response deliver on the long sought for dynamic all-organic optical elements to be incorporated in microcircuits.

Anti-malarial, cytotoxicity and molecular docking studies of quinolinyl chalcones as potential anti-malarial agent.

The quinolinyl chalcones series (A1-A14) were screened for antimalarial activity. According to in vitro antimalarial studies, many quinolinyl chalcones are potentially active against CQ-sensitive and resistance P. falciparum strains with no toxicity against Vero cell lines. The most active quinolinyl chalcones A4 (with IC50 0.031 µM) made a stable A4-heme complex with - 25 kcal/mole binding energy and also showed strong π-π interaction at 3.5 Å. Thus, the stable A4-heme complex formation suggested that these quinolinyl chalcones act as a blocker for heme polymerization. The docking results of quinolinyl chalcones with Pf-DHFR showed that the halogenated benzene part of quinolinyl chalcones made strong interaction with Pf-DHFR as compared to quinoline part. A strong A4-Pf-DHFR complex was formed with low binding energy (- 11.04 kcal/mole). The ADMET properties of quinolinyl chalcones were also studied. The in vivo antimalarial studies also confirmed the A4 as an active antimalarial agent.

Robust Inference after Random Projections via Hellinger Distance for Location-Scale Family.

Big data and streaming data are encountered in a variety of contemporary applications in business and industry. In such cases, it is common to use random projections to reduce the dimension of the data yielding compressed data. These data however possess various anomalies such as heterogeneity, outliers, and round-off errors which are hard to detect due to volume and processing challenges. This paper describes a new robust and efficient methodology, using Hellinger distance, to analyze the compressed data. Using large sample methods and numerical experiments, it is demonstrated that a routine use of robust estimation procedure is feasible. The role of double limits in understanding the efficiency and robustness is brought out, which is of independent interest.

Cooperative Vehicular Networking: A Survey.

With the remarkable progress of cooperative communication technology in recent years, its transformation to vehicular networking is gaining momentum. Such a transformation has brought a new research challenge in facing the realization of cooperative vehicular networking (CVN). This paper presents a comprehensive survey of recent advances in the field of CVN. We cover important aspects of CVN research, including physical, medium access control, and routing protocols, as well as link scheduling and security. We also classify these research efforts in a taxonomy of cooperative vehicular networks. A set of key requirements for realizing the vision of cooperative vehicular networks is then identified and discussed. We also discuss open research challenges in enabling CVN. Lastly, the paper concludes by highlighting key points of research and future directions in the domain of CVN.

Association of In-hospital outcome of Acute Kidney Injury (AKI) with etiology among newborns at a tertiary care unit.

OBJECTIVE: To determine association of in-hospital outcome of AKI with etiology in newborns at a tertiary care hospital. METHODS: This descriptive cross-sectional study was conducted at Department of Pediatric Neonatology, The Children's Hospital and Institute of the Child Health, Multan by using non-probability purposive sampling technique from June 2016 to June 2017. A total of 101 newborns diagnosed with acute kidney injury were registered. Etiological factors were assessed and these patients were followed till discharge to monitor in-hospital outcomes. RESULTS: Of these 101 newborns, 75 (74.3%) were boys while 26 (25.7%) were girls. Mean age of these newborns was 7.59 ± 6.13 days (range; 1 day to 28 days). Mean age of the boys was 5.73 ± 7.20 days while that of girls was 6.77 ± 6.16 days. (p=0.515). Mean weight of these neonates was 2545.05 ± 600.42 grams (range; 1000 grams to 4000 grams). Mean serum potassium level was 4.94 ± 0.92 mgEq/L ranging from 3.1 mgEq/L to 7.0 mgEq/L. Mean urea level was 73.35 ± 27.65 mg/dl ranging from 18 mg/dl to 206 mg/dl. Mean serum creatinine level was 1.98 ± 0.27 mg/dl, ranging from 1.6 mg/dl to 2.8 mg/dl. Mean serum sodium level was 145.72 ± 12.64 mgEq/L ranging from 126 to 166 mEq/L. Eighty one (80.2%) were term babies while 20 (19.8%) were pre-term babies. Of these 101 study cases, 29 (28.7%) delivered vaginally while 72 (71.3%) through cesarean section. Delayed crying was noted in 48 (47.5%), dehydration 13 (12.9%), sepsis in 36 (35.6%) and renal malformation in only 4%. Neonatal mortality in these patients was 15 (14.9%) while 86 (85.1%) were discharged from hospital after recovery. CONCLUSION: Acute kidney disease in newborns is associated with significant disease morbidity and mortality with asphyxia and sepsis are the main etiological factors responsible. It is predominantly more common in boys compared with girls. Mortality rate was high in our study and it was significantly associated with female gender. Mortality was also associated with elevated serum sodium and urea level.

Crystal Adaptronics: Mechanically Reconfigurable Elastic and Superelastic Molecular Crystals.

Mechanically reconfigurable molecular crystals-ordered materials that can adapt to variable operating and environmental conditions by deformation, whereby they attain motility or perform work-are quickly shaping a new research direction in materials science, crystal adaptronics. Properties such as elasticity, superelasticity, and ferroelasticity, which are normally related to inorganic materials, and phenomena such as shape-memory and self-healing effects, which are well-established for soft materials, are increasingly being reported for molecular crystals, yet their mechanism, quantification, and relation to the crystal structure of organic crystals are not immediately apparent. This Minireview provides a condensed topical overview of elastic, superelastic, and ferroelastic molecular crystals, new classes of materials that bridge the gap between soft matter and inorganic materials. The occurrence and detection of these unconventional properties, and the underlying structural features of the related molecular materials are discussed and highlighted with selected prominent recent examples.

Thermally Twistable, Photobendable, Elastically Deformable, and Self-Healable Soft Crystals.

The first example of a smart crystalline material, the 2:1 cocrystal of probenecid and 4,4'-azopyridine, which responds reversibly to multiple external stimuli (heat, UV light, and mechanical pressure) by twisting, bending, and elastic deformation without fracture is reported. This material is also able to self-heal on heating and cooling, thereby overcoming the main setbacks of molecular crystals for future applications as crystal actuators. The photo- and thermomechanical effects and self-healing capabilities of the material are rooted in reversible trans-cis isomerization of the azopyridine unit and crystal-to-crystal phase transition. Fairly isotropic intermolecular interactions and interlocked crisscrossed molecular packing secure high elasticity of the crystals.