In-field deployable and facile nanosensor for the detection of pesticides residues

Local air and water should be first priority to understand the environment of any area. Different categories of contaminants behave like bottleneck situation in collection and analysis of data about abiotic factors for the understanding and resolving the environmental issues. In digital age the emerging nano technology enroll its role to meet the needs of hour. Due to increase in pesticides residues, the global health threats are on bloom because it inhibits the functionality of acetylcholinesterase (AChE) enzyme. Smart nanotechnology based system can tackle this issue and sense the pesticides residues in environment and vegetables as well. Here Au@ZnWO₄ composite is reported, for accurate detection of pesticides residues in biological food and environmental samples. The fabricated unique nanocomposite was characterized by SEM, FTIR, XRD and EDX. The characterized material used for the electrochemical detection of organophosphate pesticide (chlorpyrifos), with 1 pM LoD at a signal to noise ratio of 3. The main concern of study is to help out in disease prevention, food safety and ecosystem protection.

High performance and gate-controlled GeSe/HfS2 negative differential resistance device

A novel and astonishing p-GeSe/n-HfS2 NDR device shows a high value for the peak-to-valley current ratio in the range of 5.8.

Biotransformation and toxicity evaluation of functionalized manganese doped iron oxide nanoparticles

Safe inorganic nanomaterials are tremendously used for diagnosis and therapies. However, essential processing in the microbiological environment changed the physical properties and in situ degradability, which is evaluated meticulously. In this research article, bare, Polyethylene glycol, and citrate coated manganese doped iron oxide nanoparticles are synthesized through the coprecipitation route. Structural, magnetic, optical, and morphological analyses are performed through different characterization tools. X-ray diffraction confirmed the formation of single-phase FeMnO3 with a crystallite size of 48.91 nm. Vibrating sample magnetometer analysis confirmed the formation of soft ferromagnetic behavior of bare and coated nanoparticles (NPs). Scanning electron microscopy and transmission electron microscopy confirmed the formation of spherical shaped nanoparticles. Single-dose in vivo acute toxicity testing is performed through the intraperitoneal route of administration on groups of healthy albino rats. Elevated enzyme levels of kidney and liver are observed at day 1 but a transient decrease is observed at later stages. Through optical follow-up, degradation effects are studied by adding prepared NPs in lysosomal like medium. Finally, metabolization of degraded products based on manganese/iron ions is studied by adding apoferritin into a lysosome like solution. These studies showed partial storage of manganese ions from NPs, while no substantial transfer is observed in the case of manganese salt.

Bedtime Smart Phone Usage and Its Effects on Work-Related Behaviour at Workplace

The over usage and over dependency on digital devices, like smartphones, has been considered as a growing international epidemic. The increased dependency on gadgets, especially smartphones for personal and official uses, has also brought many detrimental effects on individual users. Hence it is vital to understand the negative effects of smartphone usage on human. Therefore, this study aims to investigate the effects of bedtime smartphone usage on work performances, interpersonal conflicts, and work engagement, via the mediating role of sleep quality among employees. Using a cross-sectional study design, a questionnaire-based field survey was conducted on 315 employees who participated as respondents. The results confirmed the negative effects of bedtime smartphone usage on sleep quality. Along with it, the effects of sleep quality on work performances, work engagements and interpersonal conflicts were also proven to be statistically significant. Regarding the mediating role of sleep quality, it was empirically evident that sleep quality mediates the relationship between bedtime smartphone usage with work performances and interpersonal conflicts. The findings revealed that bedtime smartphone usage reduces sleep quality among the employees, resulting in lower work performances and engagements while contributing to higher interpersonal conflicts. The findings concluded that smartphone usage before sleep increases the prospects of employees to be less productive, less engaged, and have more workplace conflicts. The findings warrant the continued managerial as well as academic research attention, as the smartphones are now used by many organisations to run businesses as well.

Bismuth vanadate/MXene (BiVO4/Ti3C2) heterojunction composite: enhanced interfacial control charge transfer for highly efficient visible light photocatalytic activity

We have synthesized BiVO4/Ti3C2 nanocomposite via a low-cost hydrothermal method and investigate its photocatalytic degradation activity against monoazo (methyl orange) and diazo dye (Congo red) in an aqueous solution under visible light. The physiochemical characterization exhibited that the addition of MXene in pristine BiVO4 nanocomposite led to an increase in specific surface area and reduction in optical band gap energy. MXene also helps in enhancing visible light response via a higher electron-hole pair generation rate and long lifetime. The synthesized BiVO4/Ti3C2 heterojunction composite exhibited 99.5 % degradation efficiency within 60 min for Congo red and 99.1 % for methyl orange solution in 130 min owed to a large specific surface area (1.79 m2/g), reduced band gap (1.99 eV), and low recombination rate of charge carriers. The chemical mechanism for BiVO4/Ti3C2 nanocomposite proposes that Ti3C2 role-plays as electron capture because of the higher potential of MXenes, tuning band gap energy which paves the way to excellent photocatalytic action. This work opens a new basis for developing Ti3C2 based promising and inexpensive co-catalyst for efficient solar utilization in photocatalytic-related applications in the future.

Construction of 1T-MoS2 quantum dots-interspersed (Bi1-x Fe x )VO4 heterostructures for electron transport and photocatalytic properties

The present study reports trigonal phase molybdenum disulfide quantum dots (MoS2/QDs)-decorated (Bi1-x Fe x )VO4 composite heterostructures. Initially, (Bi1-x Fe x )VO4 heterostructure nanophotocatalysts were synthesized through the hydrothermal method decorated with 1T-MoS2 via a sonication process. 1T-MoS2@(Bi1-x Fe x )VO4 heterostructures were characterized in detail for phase purity and crystallinity using XRD and Raman spectroscopy. The Raman mode evaluation indicated monoclinic, mixed monoclinic-tetragonal and tetragonal structure development with increasing Fe concentration. For physiochemical properties, SEM, EDX, XPS, PL, EPR, UV-visible and BET techniques were applied. The optical energy band gaps of 1T-MoS2@(Bi1-x Fe x )VO4 heterostructures were calculated using the Tauc plot method. It shows a blue shift initially within a monoclinic structure then a red shift with an increase of Fe concentration. 1T-MoS2@(Bi40Fe60)VO4 with 2 wt% of 1T-MoS2-QDs carrying a mixed phase exhibited higher photocatalytic activity. The enhanced photocatalytic activity is attributed to the higher electron transportation from (Bi1-x Fe x )VO4 surface onto 1T-MoS2 surface, consequently blocking the fast electron-hole recombination within (Bi1-x Fe x )VO4. 1T-MoS2 co-catalyst interaction with (Bi1-x Fe x )VO4 enhanced the light absorption in the visible region. The close contact of small 1T-MoS2-QDs with (Bi1-x Fe x )VO4 develops a high degree of crystallinity, with fewer defects showing mesoporous/nanoporous structures within the heterostructures which allows more active sites. Herein, the mechanism involved in the synthesis of heterostructures and optimum conditions for photocatalytic degradation of crystal violet dye are explored and discussed thoroughly.

EARLY MORTALITY & MORBIDITY IN MITRAL VALVE REPLACEMENT WITH TOTAL SUB-VALVULAR APPARATUS PRESERVATION, PARTIAL PRESERVATION AND NO PRESERVATION - A COMPARATIVE STUDY

Objective: To compare the early morbidity & mortality of total sub-valvular apparatus preservation technique vs partial preservation technique and no preservation technique in mitral valve replacement. Study Design: Cross-sectional comparative study. Place and Duration of Study: Department of Cardiac Surgery, Armed Forces Institute of Cardiology Rawalpindi, from Jan 2017 to Dec 2018. Methodology: One hundred fifty seven patients who underwent Mitral valve replacement were included in study. These patients were divided into three groups; group “A” comprised of those patients with total subvalvular apparatus preservation (n1=46), group “B” comprised of those patients with partial sub-valvular apparatus preservation (n2=70), group “C” comprised of those patients with no sub-valvular apparatus preservation(n3=41). Results: There were no statistical difference in the pre-operative data of the patients. No statistical difference noted in cross clamp & bypass time (p>0.05). The early morbidity in terms of ICU stay, Ventilation time, Inotropic supports, post-operative bleeding, Blood transfusion, postoperative rhythm abnormality & Re-exploration were statically significant (p<0.05). The mortality rate of patients with total sub-valvular apparatus preservation was 2.17% which is significantly less than those with partial preservation (2.85%) & no preservation (9.75%). Conclusions: Mitral valve replacement with total subvalvular apparatus preservation had low postoperative morbidity & mortality in comparison with partial and no preservation techniques.

Tunneling-based rectification and photoresponsivity in black phosphorus/hexagonal boron nitride/rhenium diselenide van der Waals heterojunction diode

Tunneling-based van der Waals (vdW) heterostructures composed of layered transition metal dichalcogenides (TMDs) are emerging as a unique compact system that provides new research avenues in electronics and optoelectronics. Here, we designed a black phosphorus (BP)/rhenium diselenide (ReSe2) and black phosphorus (BP)/hexagonal boron nitride (h-BN)/rhenium diselenide (ReSe2) vdW heterojunction-based diode and studied the tunneling-based different phenomena, such as rectification, negative differential resistance (NDR) and backward rectification. Further, we measured a gate-tunable and tunneling-based rectifying current in BP/ReSe2 and BP/h-BN/ReSe2 heterojunction diodes, and achieved the highest tunneling-based rectification ratio of up to (RR ≈ 3.4 × 107). The high rectifying current is explained using the Simmons-based approximation through direct tunneling (DT) and Fowler-Nordheim tunneling (FNT) in low and high bias regimes. Furthermore, we extracted the photoresponsivity (R ≈ 12 mA W-1) and external quantum efficiency (EQE ≈ 2.79%) under an illuminated laser light source of wavelength 532 nm. Finally, we demonstrated the potential application of our heterostructure devices, such as a binary inverter, rectifier and switching operation at a high frequency. Our tunneling-based heterostructure device could operate at frequencies up to the GHz range. Therefore, our findings provide a new paragon to use the TMD-based vdW heterostructure in electronic and optoelectronic applications, such as multi-valued logic.

Secure Trust-Based Blockchain Architecture to Prevent Attacks in VANET

Vehicular ad hoc networks (VANET) are also known as intelligent transportation systems. VANET ensures timely and accurate communications between vehicle to vehicle (V2V) and vehicle to infrastructure (V2I) to improve road safety and enhance the efficiency of traffic flow. Due to its open wireless boundary and high mobility, VANET is vulnerable to malicious nodes that could gain access into the network and carry out serious medium access control (MAC) layer threats, such as denial of service (DoS) attacks, data modification attacks, impersonation attacks, Sybil attacks, and replay attacks. This could affect the network security and privacy, causing harm to the information exchange within the network by genuine nodes and increase fatal impacts on the road. Therefore, a novel secure trust-based architecture that utilizes blockchain technology has been proposed to increase security and privacy to mitigate the aforementioned MAC layer attacks. A series of experiment has been conducted using the Veins simulation tool to assess the performance of the proposed solution in the terms of packet delivery ratio (PDR), end-to-end delay, packet loss, transmission overhead, and computational cost.

Impact of the cognitive learning factors on sustainable organizational development

Background

Organizational cognition is a system and process aims at the improvement of organizational learning and development. It subsumes attention, leadership, culture, structure, empowerment, knowledge workers and decision-making and problem-solving processes.

Objective

The focus of this study is to assess the impact of the cognitive learning factors on sustainable Organizational development.

Methodology

Data was collected from 22 universities in Pakistan and 137 faculty members participated in the survey. Cross-sectional quantitative technique based on survey and convenient sampling was adopted for data collection. SPSS was used for data analysis.

Results

The results indicate significant impact of the cognitive factors on the Organizational development in the learning organizations like universities. Among all, knowledge workers and empowerment was found more significant as compared to other cognitive elements.

Recommendation

The study recommends further exploration of other cognitive and contextual elements for boosting learning and development.

Efficient multicolor tunability of ultrasmall ternary-doped LaF3 nanoparticles: energy conversion and magnetic behavior

Luminescence-tunable multicolored LaF₃:xCe³⁺,xGd³⁺,yEu³⁺ (x = 5; y = 1, 5, 10, and 15 mol%) nanoparticles have been synthesized via a low cost polyol method. Powder X-ray diffraction and high-resolution transmission electron microscopy studies confirm the hexagonal phase of the LaF₃:xCe³⁺,xGd³⁺,yEu³⁺ nanophosphors with average sizes (oval shape) ranging from 5 to 7 nm. Energy-dispersive X-ray spectroscopy analyses show the uniform distribution of Ce³⁺, Gd³⁺, and Eu³⁺ dopants in the LaF₃ host matrix. The photoluminescence spectra and electron paramagnetic resonance measurements guarantee the presence of Eu²⁺, corroborated through DC susceptibility measurements of the samples displaying paramagnetic behavior at 300 K, whereas weak ferromagnetic ordering is shown at 2 K. The non-radiative energy transfer processes from the 4f(²F_5/2) → 5d state (Ce³⁺) to the intraconfigurational 4f excited levels of rare earth ions and simultaneous emissions in the visible region from the 4f⁶5d¹ (Eu²⁺) and ⁵D₀ (Eu³⁺) emitting levels, leading to overlapped broad and narrow emission bands, have been proclaimed. The energy transfer mechanism proposes involvement of the Gd³⁺ ion sub-lattice as the bridge and finally trapping by Eu^2+/3+, upon excitation of the Ce³⁺ ion. The calculation of experimental intensity parameters (Ω_2,4) has been discussed and the highest emission quantum efficiency (η = 85%) of the Eu³⁺ ion for the y = 10 mol% sample is reported. The advantageous existence of the Eu²⁺/Eu³⁺ ratio along with variously doped nanomaterials described in this work, results in tunable emission color in the blue-white-red regions, highlighting the potential application of the samples in solid-state lighting devices, scintillation devices, and multiplex detection.

Ferritin Protein Regulates the Degradation of Iron Oxide Nanoparticles

Proteins implicated in iron homeostasis are assumed to be also involved in the cellular processing of iron oxide nanoparticles. In this work, the role of an endogenous iron storage protein-namely the ferritin-is examined in the remediation and biodegradation of magnetic iron oxide nanoparticles. Previous in vivo studies suggest the intracellular transfer of the iron ions released during the degradation of nanoparticles to endogenous protein cages within lysosomal compartments. Here, the capacity of ferritin cages to accommodate and store the degradation products of nanoparticles is investigated in vitro in the physiological acidic environment of the lysosomes. Moreover, it is questioned whether ferritin proteins can play an active role in the degradation of the nanoparticles. The magnetic, colloidal, and structural follow-up of iron oxide nanoparticles and proteins in lysosome-like medium confirms the efficient remediation of potentially harmful iron ions generated by nanoparticles within ferritins. The presence of ferritins, however, delays the degradation of particles due to a complex colloidal behavior of the mixture in acidic medium. This study exemplifies the important implications of intracellular proteins in processes of degradation and metabolization of iron oxide nanoparticles.

Pressure-induced changes in the electronic structure and enhancement of the thermoelectric performance of SnS2: a first principles study

Hydrostatic pressure reduces the band gap and increases the ZT value of SnS₂.

Surface and interface interplay on the oxidizing temperature of iron oxide and Au–iron oxide core–shell nanoparticles

Formation of core and shell shape through tuning the reaction time as well as the oxidizing temperatures. Spherical–spherical and spherical triangular shaped core–shell structures have been obtained at an optimum oxidation temperature of 150 °C.

The One Year Fate of Iron Oxide Coated Gold Nanoparticles in Mice

Safe implementation of nanotechnology and nanomedicine requires an in-depth understanding of the life cycle of nanoparticles in the body. Here, we investigate the long-term fate of gold/iron oxide heterostructures after intravenous injection in mice. We show these heterostructures degrade in vivo and that the magnetic and optical properties change during the degradation process. These particles eventually eliminate from the body. The comparison of two different coating shells for heterostructures, amphiphilic polymer or polyethylene glycol, reveals the long lasting impact of initial surface properties on the nanocrystal degradability and on the kinetics of elimination of magnetic iron and gold from liver and spleen. Modulation of nanoparticles reactivity to the biological environment by the choice of materials and surface functionalization may provide new directions in the design of multifunctional nanomedicines with predictable fate.

Unravelling kinetic and thermodynamic effects on the growth of gold nanoplates by liquid transmission electron microscopy

The growth of colloidal nanoparticles is simultaneously driven by kinetic and thermodynamic effects that are difficult to distinguish. We have exploited in situ scanning transmission electron microscopy in liquid to study the growth of Au nanoplates by radiolysis and unravel the mechanisms influencing their formation and shape. The electron dose provides a straightforward control of the growth rate that allows quantifying the kinetic effects on the planar nanoparticles formation. Indeed, we demonstrate that the surface-reaction rate per unit area has the same dose-rate dependent behavior than the concentration of reducing agents in the liquid cell. Interestingly, we also determine a critical supply rate of gold monomers for nanoparticle faceting, corresponding to three layers per second, above which the formation of nanoplates is not possible because the growth is then dominated by kinetic effects. At lower electron dose, the growth is driven by thermodynamic and the formation and shape of nanoplates are directly related to the twin-planes formed during the growth.

[Life cycle of magnetic nanoparticles in the organism]

The use of nanomaterials drastically increases and yet their behavior in living organisms remains poorly examined. At the same time a better comprehension of the interactions between nanoparticles and the biological environment would allow us to limit potential nanoparticle-based toxicity and fully exploit nanoparticles medical applications. In this perspective, it is high time we develop methods to detect, quantify and follow the evolution of nanoparticles in the complex biological environment, spanning all relevant scales from the nanometer up to the tissue level. In this work we follow the life cycle of magnetic nanoparticles in vivo, focusing on their transformations over time from administration to elimination. As opposed to traditional nano-toxicological approaches, we herein take the nanoparticle perspective and try to establish how biological environment might impact the particles properties and their fate (interaction with proteins, cell confinement, degradation...) from their initial state to a series of changes a nanoparticle might undergo on its journey throughout the organism.

Biodegradation mechanisms of iron oxide monocrystalline nanoflowers and tunable shield effect of gold coating

Understanding the relation between the structure and the reactivity of nanomaterials in the organism is a crucial step towards efficient and safe biomedical applications. The multi-scale approach reported here, allows following the magnetic and structural transformations of multicore maghemite nanoflowers in a medium mimicking intracellular lysosomal environment. By confronting atomic-scale and macroscopic information on the biodegradation of these complex nanostuctures, we can unravel the mechanisms involved in the critical alterations of their hyperthermic power and their Magnetic Resonance imaging T1 and T2 contrast effect. This transformation of multicore nanoparticles with outstanding magnetic properties into poorly magnetic single core clusters highlights the harmful influence of cellular medium on the therapeutic and diagnosis effectiveness of iron oxide-based nanomaterials. As biodegradation occurs through surface reactivity mechanism, we demonstrate that the inert activity of gold nanoshells can be exploited to protect iron oxide nanostructures. Such inorganic nanoshields could be a relevant strategy to modulate the degradability and ultimately the long term fate of nanomaterials in the organism.

Biodegradation of iron oxide nanocubes: high-resolution in situ monitoring

The long-term fate of nanomaterials in biological environment represents a critical matter, which determines environmental effects and potential risks for human health. Predicting these risks requires understanding of nanoparticle transformations, persistence, and degradation, some issues somehow ignored so far. Safe by design, inorganic nanostructures are being envisioned for therapy, yet fundamental principles of their processing in biological systems, change in physical properties, and in situ degradability have not been thoroughly assessed. Here we report the longitudinal visualization of iron oxide nanocube transformations inflicted by the intracellular-like environment. Structural degradation of individual nanocubes with two different surface coatings (amphiphilic polymer shell and polyethylene glycol ligand molecules) was monitored at the atomic scale with aberration-corrected high-resolution transmission electron microscopy. Our results suggest that the polymer coating controls surface reactivity and that availability and access of chelating agents to the crystal surface govern the degradation rate. This in situ study of single nanocube degradation was compared to intracellular transformations observed in mice over 14 days after intravenous injection, revealing the role of nanoparticle clustering, intracellular sorting within degradation compartments, and iron transfer and recycling into ferritin storage proteins. Our approach reduces the gap between in situ nanoscale observations in mimicking biological environments and in vivo real tracking of nanoparticle fate.