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Psoriasis is a chronic inflammatory disease that affects more than 60 million people worldwide. Its pathogenesis involves the interplay of immune and oxidative stress mechanisms with feedback loops reinforced between them. Alleviating the state of oxidative stress will break this loop and relieve chronic inflammation, making it a potential therapeutic target. We synthesized a kind of molybdenum nanoparticle which reduced reactive oxygen species (ROS) in HaCaT cells in a psoriasis-mimicking environment and decreased the production of inflammatory mediators such as IL-17A, IL-23, IFN-γ, and TNF-α, which play a crucial role in the onset of psoriasis. In a mouse model of psoriasis, molybdenum particles in its specific nanoscale alleviated erythema, scaling, and thickening of lesions and reduced the infiltration of inflammatory cells and the expression of relevant inflammatory mediators in skin lesions. The levels of phosphorylated p65 were significantly reduced in both in vitro and in vivo models after the application of molybdenum nanoparticles, suggesting that this material, especially due to its nanoscale, may reduce the production of inflammatory mediators and proliferation of keratinocytes through a ROS/NF-κB axis, thereby improving psoriasis symptoms. Our study suggests that molybdenum nanoparticles are a promising treatment strategy for patients with psoriasis. [ABSTRACT FROM AUTHOR]

Disordered ridge-splitting on laser-induced periodic surface structures (LIPSSs) often reduces structure quality and degrades application performance but introduces a potential route for laser structuring accuracy with access to the deep-subwavelength scale. Here, nanolithography based on the homogeneous ridge-splitting mechanism is implemented on a molybdenum surface using two-color (400 and 800 nm) temporally delayed femtosecond laser pulses with identical linear polarizations. The achieved splitting LIPSS, with a periodicity down to 140 nm and a feature size down to 70 nm, was uniformly distributed in the long range without any wavy or interruption defects, presenting improvements on the structure's accuracy and quality relative to the observation of single-beam femtosecond 400 nm laser irradiation. The generation and suppression of the homogeneous ridge-splitting phenomenon can be manipulated via altering the time delay or the fluences of the two-color laser pulses, which results in transitions between the regular near-subwavelength and deep-subwavelength LIPSSs. The underlying physical origins are attributed to the excitation of various electromagnetic field enhancement modes during the transiently correlated dynamic process of two-color laser–material interactions. Our investigations facilitate the laser nanostructuring of metals with an accessible 100 nm feature size, and the nanostructured Mo surface enables specific applications in the field of concentrated solar energy devices. [ABSTRACT FROM AUTHOR]

In electrochemical energy storage and conversion systems, urea oxidation reaction (UOR) can produce hydrogen and mitigate pollution from urea-rich wastewater in a low-energy manner, whereas the development of this technique was limited via a lack of economical and cost-effective UOR catalysts. Herein, a unique electrocatalyst of MoO3/Ni-N-C was synthesized from a Mo element-incorporated Ni-MOF by heating under an inert atmosphere. The prepared MoO3/Ni-N-C electrode shows superior activity toward UOR, which only needs a low potential of 1.42 V (vs RHE) at 50 mA cm–2 in 1.0 M KOH with 0.5 M urea. The excellent performance for UOR is attributed to the synergistic effect between molybdenum and nickel, the modulation of the electronic structure for the nickel site by MoO3, accelerating the charge transfer, and tuning the reaction interface adsorption energy to enhance electrocatalytic activity. This work provides strategies and directions for exploring other advanced UOR electrode material designs. [ABSTRACT FROM AUTHOR]

The real-time monitoring of low-concentration cytokines such as TNF-α in sweat can aid clinical physicians in assessing the severity of inflammation. The challenges associated with the collection and the presence of impurities can significantly impede the detection of proteins in sweat. This issue is addressed by incorporating a nanosphere array designed for automatic sweat transportation, coupled with a reusable sensor that employs a Nafion/aptamer-modified MoS 2 field-effect transistor. The nanosphere array with stepwise wettability enables automatic collection of sweat and blocks impurities from contaminating the detection zone. This device enables direct detection of TNF-α proteins in undiluted sweat, within a detection range of 10 fM to 1 nM. The use of an ultrathin, ultraflexible substrate ensures stable electrical performance, even after up to 30 extreme deformations. The findings indicate that in clinical scenarios, this device could potentially provide real-time evaluation and management of patients' immune status via sweat testing.

Recent research studies have focused on energy storage systems such as supercapacitors with high power density, good operational safety, and durable cycling life. Hence, the structure design effectively promotes the excellent performance of pseudocapacitive materials as an electrode in a supercapacitor. In this research, Co3O4/MoCo/LDH is prepared and fabricated as a binder-free electrode on the nickel foam. The Co3O4 nanowires (NWs) and MoCo layered double hydroxides (LDHs) are synthesized via a hydrothermal pathway with a combination of calcination processes and characterized by various techniques, including attenuated total reflectance-infrared (ATR-IR), field emission-scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and X-ray diffraction (XRD) patterns. This electrode enlarges active sites and enhances the rates of ion/electron diffusion. As a result, the Co3O4/MoCo/LDH/NF electrode demonstrates a superb specific capacitance of 2677 F g–1 at 1.0 A g–1, great cycling stability after 5000 cycles (maintaining 93.2% of its initial capacitance) at 9.0 A g–1, and an excellent capacity retention rate of 62.86% at 15 A g–1, which shows better performance than MoCo LDH/NF and Co3O4 NWs/NF electrodes. Furthermore, an asymmetric supercapacitor is fabricated by Co3O4/MoCo/LDH and activated carbon; Co3O4/MoCo/LDH/NF//AC ASC exhibits a specific capacitance of 190.2 F g–1 at 1.0 A g–1 and an outstanding energy density of 67.62 Wh kg–1 at a high power density of 800 W kg–1. Therefore, it is a promising electrode for energy storage applications. [ABSTRACT FROM AUTHOR]

In this work, we present an array-based chemical nose sensor that utilizes a set of ensemble-modified aptamer (EMAmer) probes to sense subtle physicochemical changes on the cell surface for cancer cell identification. The EMAmer probes are engineered by domain-selective incorporation of different types and/or copies of positively charged functional groups into DNA scaffolds, and their differential interactions with cancer cells can be transduced through competitive adsorption of fluorophore-labeled EMAmer probes loaded on MoS 2 nanosheets. We demonstrate that this MoS 2 -EMAmer-based sensor array enables rapid and effective discrimination among six types of cancer cells and their mixtures with a concentration of 10 4 cells within 60 min, achieving a 94.4% accuracy in identifying blinded unknown cell samples. The established MoS 2 -EMAmer sensing platform is anticipated to show significant promise in the advancement of cancer diagnostics.

The production of wood-based panels has a significant demand for mechanically strong and flexible biomass adhesives, serving as alternatives to nonrenewable and toxic formaldehyde-based adhesives. Nonetheless, plywood usually exhibits brittle fracture due to the inherent trade-off between rigidity and toughness, and it is susceptible to damage and deformation defects in production applications. Herein, inspired by the microstructure of dragonfly wings and the cross-linking structure of plant cell walls, a soybean meal (SM) adhesive with great strength and toughness was developed. The strategy was combined with a multiple assembly system based on the tannic acid (TA) stripping/modification of molybdenum disulfide (MoS 2 @TA) hybrids, phenylboronic acid/quaternary ammonium doubly functionalized chitosan (QCP), and SM. Motivated by the microstructure of dragonfly wings, MoS 2 @TA was tightly bonded with the SM framework through Schiff base and strong hydrogen bonding to dissipate stress energy through crack deflection, bridging, and immobilization. QCP imitated borate chemistry in plant cell walls to optimize interfacial interactions within the adhesive by borate ester bonds, boron-nitrogen coordination bonds, and electrostatic interactions and dissipate energy through sacrificial bonding. The shear strength and fracture toughness of the SM/QCP/MoS 2 @TA adhesive were 1.58 MPa and 0.87 J, respectively, which were 409.7% and 866.7% higher than those of the pure SM adhesive. In addition, MoS 2 @TA and QCP gave the adhesive good mildew resistance, durability, weatherability, and fire resistance. This bioinspired design strategy offers a viable and sustainable approach for creating multifunctional strong and tough biobased materials.

Lateral flow immunoassay (LFIA) has been widely used for the early diagnosis of diseases. However, conventional colorimetric LFIA possesses limited sensitivity, and the single-mode readout signal is easily affected by the external environment, leading to insufficient accuracy. Herein, multifunctional Fe 3 O 4 @MoS 2 @Pt nanotags with a unique "pompon mum"-like structure were triumphantly prepared, exhibiting excellent peroxidase (POD)-like activity, photothermal properties, and magnetic separation capability. Furthermore, the Fe 3 O 4 @MoS 2 @Pt nanotags were used to establish dual-mode LFIA (dLFIA) for the first time, enabling the catalytic colorimetric and photothermal dual-mode detection of severe acute respiratory syndrome coronavirus 2 nucleocapsid protein (SARS-CoV-2 NP) and influenza A (H1N1). The calculated limits of detection ( c LODs) of SARS-CoV-2 NP and H1N1 were 80 and 20 ng/mL in catalytic colorimetric mode and 10 and 8 ng/mL in photothermal mode, respectively, demonstrating about 100 times more sensitive than the commercial colloidal Au-LFIA strips (1 ng/mL for SARS-CoV-2 NP; 1 μg/mL for H1N1). The recovery rates of dLFIA in simulated nose swab samples were 95.2-103.8% with a coefficient of variance of 2.3-10.1%. These results indicated that the proposed dLFIA platform showed great potential for the rapid diagnosis of respiratory viruses.

Chemical stability is closely associated with the transformations and bioavailabilities of engineered nanomaterials and is a key factor that governs broader and long-term application. With the growing utilization of molybdenum disulfide (MoS 2 ) nanosheets in water treatment and purification processes, it is crucial to evaluate the stability of MoS 2 nanosheets in aquatic environments. Nonetheless, the effects of anionic species on MoS 2 remain largely unexplored. Herein, the stability of chemically exfoliated MoS 2 nanosheets (ceMoS 2 ) was assessed in the presence of inorganic anions. The results showed that the chemical stability of ceMoS 2 was regulated by the nucleophilicities and the resultant charging effects of the anions in aquatic systems. The anions promote the dissolution of ceMoS 2 by triggering a shift in the chemical potential of the ceMoS 2 surface as a function of the anion nucleophilicity (i.e., charging effect). Fast charging with HCO 3 - and HPO 4 2- /H 2 PO 4 - was validated by a phase transition from 1T to 2H and the emergence of Mo V , and it promoted oxidative dissolution of the ceMoS 2 . Additionally, under sunlight, ceMoS 2 dissolution was accelerated by NO 3 - . These findings provide insight into the ion-induced fate of ceMoS 2 and the durability and risks of MoS 2 nanosheets in environmental applications.

2D nanosheets (NSs) have been widely used in drug-related applications. However, a comprehensive investigation into the cytotoxicity mechanism linked to the redox activity is lacking. In this study, with cytochrome c (Cyt c ) as the model biospecies, the cytotoxicity of 2D NSs was evaluated systematically based on their redox effect with microfluidic techniques. The interface interaction, dissolution, and redox effect of 2D NSs on Cyt c were monitored with pulsed streaming potential (SP) measurement and capillary electrophoresis (CE). The relationship between the redox activity of 2D NSs and the function of Cyt c was evaluated in vitro with Hela cells. The results indicated that the dissolution and redox activity of 2D NSs can be simultaneously monitored with CE under weak interface interactions and at low sample volumes. Both WS 2 NSs and MoS 2 NSs can reduce Cyt c without significant dissolution, with reduction rates measured at 6.24 × 10 -5 M for WS 2 NSs and 3.76 × 10 -5 M for MoS 2 NSs. Furthermore, exposure to 2D NSs exhibited heightened reducibility, which prompted more pronounced alterations associated with Cyt c dysfunction, encompassing ATP synthesis, modifications in mitochondrial membrane potential, and increased reactive oxygen species production. These observations suggest a positive correlation between the redox activity of 2D NSs and their redox toxicity in Hela cells. These findings provide valuable insight into the redox properties of 2D NSs regarding cytotoxicity and offer the possibility to modify the 2D NSs to reduce their redox toxicity for clinical applications.

The electrocatalytic nitrate reduction reaction (NO 3 RR) has recently emerged as a promising technique for readily converting aqueous nitrate (NO 3 - ) pollutants into valuable ammonia (NH 3 RR. There are several natural enzymes that incorporate molybdenum (Mo) and that can activate NO 3 RR. There are several natural enzymes that incorporate molybdenum (Mo) and that can activate NO 3 - . Based on this, a cadmium (Cd) single-atom anchored Mo 2 TiC 2 T x electrocatalyst (referred to as Cd SA -Mo 2 TiC 2 T x ) through the NO 3 RR to generate NH 3 was rationally designed and demonstrated. In an H-type electrolysis cell and at a current density of 42.5 mA cm -2 , the electrocatalyst had a Faradaic efficiency of >95% and an impressive NH 3 yield rate of 48.5 mg h -1 cm -2 . Moreover, the conversion of NO 3 - to NH 3 on the Cd SA -Mo 2 TiC 2 T x surface was further revealed by operando attenuated total reflection Fourier-transform infrared spectroscopy and an electrochemical differential mass spectrometer. The electrocatalyst significantly outperformed Mo 2 TiC 2 T x as well as reported state-of-the-art catalysts. Density functional theory calculations revealed that Cd SA -Mo 2 TiC 2 T x decreased the ability of the d-p orbital to hybridize with NH 3 * intermediates, thereby decreasing the activation energy of the potential-determining step. This work not only highlights the application prospects of heavy metal single-atom catalysts in the NO 3 RR but also provides examples of bio-inspired electrocatalysts for the synthesis of NH 3 .

The high selectivity and fast ion response of all-solid sodium ion selective electrodes were widely applied in human sweat analysis. However, the potential drift due to insufficient interfacial capacitance leads to the deterioration of its stability and ultimately affects the potential accuracy of ion analysis. Designing a novel ion-electron transduction layer between the electrode and the ion selective membrane is an effective method to stabilize the interfacial potential. Herein, the SnS 2 -MoS 2 heterojunction material was constructed by doping Sn in MoS 2 nanosheets and used as the ion electron transduction layers of an all-solid sodium ion selective electrode for the first time, achieving the stable and efficient detection of Na + ions. The proposed electrode exhibited a Nernst slope of 57.86 mV/dec for the detection of Na + ions with a detection limit of 10 -5.7 M in the activity range of 10 -6 -10 -1 M. Via the electronic interaction at the heterojunction interfaces between SnS 2 and MoS 2 materials, the micro-nanostructure of the SnS 2 -MoS 2 heterojunction was changed and SnS 2 -MoS 2 as the ion-electron transduction layer acquired excellent capacitance (699 μF) and hydrophobicity (132°), resulting in a long-term potential stability of 1.37 μV/h. It was further proved that the large capacitance and high hydrophobicity of the ion-electron transduction layer are primary reasons for the excellent stability of the all-solid sodium ion selective electrode toward Na + ions.

Transition metal dichalcogenide (TMD) materials hold great promise for gas sensors working at room temperature (RT). But the low response and slow dynamics derived from pristine TMDs remain a challenge toward their real applications. In this work, we report an efficient N-doping strategy to modulate the electronic structure of MoS 2 nanosheets (N-MoS 2 ) to achieve improved detection toward NO 2 . The effect of N-doping on the sensor properties, which has been rarely investigated, is elucidated by both experimental and computational studies. Due to N-doping, the Fermi level of N-MoS 2 decreased from -5.29 to -5.33 eV and the band gap was reduced from 1.79 to 1.65 eV. The smaller band gap indicated the reduced resistance of N-MoS 2 compared to that of original MoS 2 . As a result, the response of the MoS 2 sensor to 10 ppm of NO 2 was improved from 1.23 to 2.31 at RT. The sensor also has a limit of detection (LOD) of 62.5 ppb. To explain the effect of N-doping, density functional theory (DFT) calculations were conducted to figure out the important roles played by N-doping. This work demonstrates a pathway to modulate the chemical and electronic structures of TMD materials for advanced sensors.

Molybdenum disulfide (nano-MoS 2 ) nanomaterials have shown great potential for biomedical and catalytic applications due to their unique enzyme-mimicking properties. However, their potential agricultural applications have been largely unexplored. A key factor prior to the application of nano-MoS 2 in agriculture is understanding its behavior in a complex soil-plant system, particularly in terms of its transformation. Here, we investigate the distribution and transformation of two types of nano-MoS 2 (MoS 2 nanoparticles and MoS 2 nanosheets) in a soil-soybean system through a combination of synchrotron radiation-based X-ray absorption near-edge spectroscopy (XANES) and single-particle inductively coupled plasma mass spectrometry (SP-ICP-MS). We found that MoS 2 nanoparticles (NPs) transform dynamically in soil and plant tissues, releasing molybdenum (Mo) and sulfur (S) that can be incorporated gradually into the key enzymes involved in nitrogen metabolism and the antioxidant system, while the rest remain intact and act as nanozymes. Notably, there is 247.9 mg/kg of organic Mo in the nodule, while there is only 49.9 mg/kg of MoS 2 NPs. This study demonstrates that it is the transformation that leads to the multifunctionality of MoS 2 , which can improve the biological nitrogen fixation (BNF) and growth. Therefore, MoS 2 NPs enable a 30% increase in yield compared to the traditional molybdenum fertilizer (Na 2 MoO 4 ). Excessive transformation of MoS 2 nanosheets (NS) leads to the overaccumulation of Mo and sulfate in the plant, which damages the nodule function and yield. The study highlights the importance of understanding the transformation of nanomaterials for agricultural applications in future studies.

Acute respiratory disease syndrome (ARDS) is a common critical disease with high morbidity and mortality rates, yet specific and effective treatments for it are currently lacking. ARDS was especially apparent and rampant during the COVID-19 pandemic. Excess reactive oxygen species (ROS) production and an uncontrolled inflammatory response play a critical role in the disease progression of ARDS. Herein, we developed molybdenum nanodots (MNDs) as a functional nanomaterial with ultrasmall size, good biocompatibility, and excellent ROS scavenging ability for the treatment of acute lung injury (ALI). MNDs, which were administered intratracheally, significantly ameliorated lung oxidative stress, inflammatory response, protein permeability, and histological severity in ALI mice without inducing any safety issues. Importantly, transcriptomics analysis indicated that MNDs protected lung tissues by inhibiting the activation of the Nod-like receptor protein 3 (NLRP3)-dependent pyroptotic pathway. This work presents a promising therapeutic agent for patients suffering from ARDS.

Herein, a sensitive and selective electrochemical sensor based on aptamer folding was constructed to detect aflatoxin B1 (AFB1) in peanuts. Specifically, polyethylenimine-functionalized multiwalled carbon nanotubes modified with molybdenum disulfide (MoS 2 @MWCNTs-PEI) were used as the electrode matrix to enable a large specific surface area, which were characterized by the Randles-Sevcik equation. Additionally, AuNPs were used to immobilize the aptamer via the Au-S covalent bond and provide a favorable microenvironment for signal enhancement. Methylene blue (MB) was modified at the proximal 3' termini of the aptamer as the capture probe, while the signal transduction of the sensor was obtained through changes in conformation and position of MB induced by the binding between AFB1 and the probe. Changes in spatial conformation could be recorded by electrochemical methods more readily. This electrochemical aptasensor demonstrated remarkable sensitivity to AFB1 with an extensive detection range (1 pg/mL to 100 ng/mL) and a lower limit detection (1.0 × 10 -3 ng/mL). Moreover, using the constructed aptasensor, AFB1 was identified successfully in peanut samples, with recoveries ranging from 95.83 to 107.53%, illustrating its potential use in determining AFB1 in food.

In this report, we investigate the room-temperature gas sensing performance of heterostructure transition metal dichalcogenide (MoSe 2 /MoS 2 , WS 2 /MoS 2 , and WSe 2 /MoS 2 ) thin films grown over a silicon substrate using a pulse laser deposition technique. The sensing response of the aforementioned sensors to a low concentration range of NO 2 , NH 3 , H 2 , CO, and H 2 S gases in air has been assessed at room temperature. The obtained results reveal that the heterojunctions of metal dichalcogenide show a drastic change in gas sensing performance compared to the monolayer thin films at room temperature. Nevertheless, the WSe 2 /MoS 2 -based sensor was found to have an excellent selectivity toward NO 2 gas with a particularly high sensitivity of 10 ppb. The sensing behavior is explained on the basis of a change in electrical resistance as well as carrier localization prospects. Favorably, by developing a heterojunction of diselenide and disulfide nanomaterials, one may find a simple way of improving the sensing capabilities of gas sensors at room temperature.

Chronic osteomyelitis (COM), is a long-term, constant, and intractable disease mostly induced by infection from the invasion of Staphylococcus aureus ( S. aureus ) into bone cells. Here, we describe a highly effective microwave (MW) therapeutic strategy for S. aureus -induced COM based on the in situ growth of interfacial oxygen vacancy-rich molybdenum disulfide (MoS 2 )/titanium carbide (Ti 3 C 2 T x ) MXene with oxygen-deficient titanium dioxide (TiO 2-x ) on Ti 3 C 2 T x (labeled as HU-MoS 2 /Ti 3 C 2 T x ) by producing reactive oxygen species (ROS) and heat. HU-MoS 2 /Ti 3 C 2 T x produced heat and ROS, which could effectively treat S. aureus -induced COM under MW irradiation. The underlying mechanism determined by density functional theory (DFT) and MW vector network analysis was that HU-MoS 2 /Ti 3 C 2 T x formed a high-energy local electric field under MW irradiation, consequently generating more high-energy free electrons to pass and move across the interface at a high speed and accelerate by the heterointerface, which enhanced the charge accumulation on both sides of the interface. Moreover, these charges were captured by the oxygen species adsorbed at the HU-MoS 2 /Ti 3 C 2 T x interface to produce ROS. MoS 2 facilitated multiple reflections and scattering of electromagnetic waves as well as enhanced impedance matching. Ti 3 C 2 T x enhanced the conduction loss of electromagnetic waves, while functional groups induced dipole polarization to enhance attenuation of MW.

Deficient catalytic sensitivity to the tumor microenvironment is a major obstacle to nanozyme-mediated tumor therapy. Electron transfer is the intrinsic essence for a nanozyme-catalyzed redox reaction. Here, we developed a nanohole-array-induced metallic molybdenum selenide ( n- MoSe 2 ) that is enriched with Se vacancies and can serve as an electronic transfer station for cycling electrons between H 2 O 2 decomposition and glutathione (GSH) depletion. In a MoSe 2 nanohole array, the metallic phase reaches up to 84.5%, which has been experimentally and theoretically demonstrated to exhibit ultrasensitive H 2 O 2 responses and enhanced peroxidase (POD)-like activities for H 2 O 2 thermodynamic heterolysis. More intriguingly, plenty of delocalized electrons appear due to phase- and vacancy-facilitated band structure reconstruction. Combined with the limited characteristic sizes of nanoholes, the surface plasmon resonance effect can be excited, leading to the broad absorption spectrum spanning of n- MoSe 2 from the visible to near-infrared region (NIR) for photothermal conversion. Under NIR laser irradiation, metallic MoSe 2 is able to induce out-of-balance redox and metabolism homeostasis in the tumor region, thus significantly improving therapeutic effects. This study that takes advantage of phase and defect engineering offers inspiring insights into the development of high-efficiency photothermal nanozymes.

The increased popularity of wearable electronic devices has led to a greater need for advanced sensors. However, fabricating pressure sensors that are flexible, highly sensitive, robust, and compatible with large-scale fabrication technology is challenging. This work investigates a piezoresistive sensor constructed from an MXene/MoS 2 hierarchical nanostructure, which is obtained through an easy and inexpensive fabrication process. The sensor exhibits a high sensitivity of 0.42 kPa -1 (0-1.5 kPa), rapid response (∼36 ms), and remarkable mechanical durability (∼10,000 cycles at 13 kPa). The sensor has been demonstrated to be successful in detecting human motion, speech recognition, and physiological signals, particularly in analyzing human pulse. These data can be used to alert and identify irregularities in human health. Additionally, the sensing units are able to construct sensor arrays of various sizes and configurations, enabling pressure distribution imaging in a variety of application scenarios. This research proposes a cost-effective and scalable approach to fabricating piezoresistive sensors and sensor arrays, which can be utilized for monitoring human health and for use in human-machine interfaces.

While molybdenum (Mo) application can improve phosphorus (P) availability to plants by changing P speciation in the rhizosphere, the mechanistic basis of this process remains unclear. This work investigated the impact of various combinations of Mo and P treatments on root morphology, P and Mo uptake, and root transcriptome and metabolome. Mo application significantly increased soybean biomass and the number of lateral roots at both low (5 μmol) or normal (500 μmol) P levels and significantly improved P concentration and accumulation in Normal P treatment. Compared with the Normal P treatment, Low P significantly increased the number of roots, root surface area, and root acid phosphatase secretion. A total of 6811 Mo-responsive differentially expressed genes and 135 differential metabolites were identified at two P levels. At Low P, transcriptional changes significantly increased root synthesis and secretion of succinic acid, methylmalonic acid, and other organic acids as well as acid phosphatase, thereby increasing the conversion of soil aluminum-bound P and organic P into available P. At Normal P, Mo application increased P uptake mainly by increasing the number of lateral roots. Thus, Mo helps crops adapt to different P levels by regulating root anatomy and transcriptional and metabolic profiles of their roots.

One of the highly attractive research directions in the electrochemiluminescence (ECL) field is how to regulate and improve ECL efficiency. Quantum dots (QDs) are highly promising ECL materials due to their adjustable luminescence size and strong luminous efficiency. MoS 2 NSs@QDs, an ECL emitter, is synthesized via hydrothermal methods, and its ECL mechanism is investigated using cyclic voltammetry and ECL-potential curves. Then, a stable and vertical attachment of a triplex DNA (tsDNA) probe to the MoS 2 nanosheets (NSs) is applied to the electrode. Next, an innovative ECL sensor is courageously empoldered for precise and ultrasensitive detection of target miRNA-199a through the agency of ECL-resonance energy transfer (RET) strategy and a dextrous target-initiated catalytic three-arm DNA junction assembly (CTDJA) based on a toehold strand displacement reaction (TSDR) signal amplification approach. Impressively, the ingenious system not only precisely regulates the distance between energy donor-acceptor pairs leave energy less loss and more ECL-RET efficiency, but also simplifies the operational procedure and verifies the feasibility of this self-assembly process without human intervention. This study can expand MoS 2 NSs@QDs utilization in ECL biosensing applications, and the proposed nucleic acid amplification strategy can become a miracle cure for ultrasensitive detecting diverse biomarkers, which helps researchers to better study the tumor mechanism, thereby unambiguously increasing cancer cure rates and reducing the risk of recurrence.

Synergistic therapy combining photothermal therapy and photodynamic therapy is considered to be a promising approach to treat cancer, but the precise temperature control of deep tissue remains a great challenge in achieving effective treatment. Herein, a two-dimensional Bi 2 WO 6 :Nd 3+ /Yb 3+ /Er 3+ @MoS 2 nanoplatform with photothermal and photodynamic functions was constructed, where semiconductor MoS 2 serves as both a photothermal agent and a photosensitizer. The photothermal conversion performance and the reactive oxygen species generation capacity of the nanoplatform were validated under the irradiation of 808 nm laser; meanwhile, the two sets of luminescence intensity ratios ( I Yb3+ / I Nd3+ and I Er3+ / I Nd3+ ) in the biological window region were selected as near-infrared temperature probes to monitor the heat generated during the photosynergistic process in real time. The feasibility of nanoplatform as an intratissue temperature probe and antibacterial agent was further assessed by vitro experiments, which provides an idea for designing multifunctional photosynergistic therapy nanoplatform.

The sensing behavior of a MoS 2 -functionalized paper sensor towards dopamine was explored through a combinatorial approach of theoretical analysis, subsequent experimental validation, and machine-learning-driven predictive modeling of the measured electrochemical outputs. The suitability of the chosen 2D material for efficient detection of dopamine was confirmed using density functional theory. The physisorption behavior along with electrostatic interaction due to the incorporation of dopamine on MoS 2 was unraveled under the purview of theoretically estimated noncovalent interaction and charge density difference plot. The theoretical Löwdin population analysis elucidates the alteration in oxidation potential of dopamine, as observed in electrochemical experiments. The electrochemical responses of the developed sensor with the spiked serum samples showed an average accuracy of more than 96% with a limit of detection of 10 nM. Furthermore, implementation of a machine-intelligent interactive web app interface improved the resolution of the sensing platform significantly with an enhanced accuracy of nearly 99%.

Although the traditional enzyme-linked immunosorbent assay (ELISA) has been widely applied in pathogen detection and clinical diagnostics, it always suffers from complex procedures, a long incubation time, unsatisfying sensitivity, and a single signal readout. Here, we developed a simple, rapid, and ultrasensitive platform for dual-mode pathogen detection based on a multifunctional nanoprobe integrated with a capillary ELISA (CLISA) platform. The novel capture antibodies-modified capillaries can act as a swab to combine in situ trace sampling and detection procedures, eliminating the dissociation between sampling and detection in traditional ELISA assays. With excellent photothermal and peroxidase-like activity, the Fe 3 O 4 @MoS 2 nanoprobe with a unique p-n heterojunction was chosen as an enzyme substitute and amplified signal tag to label the detection antibody for further sandwich immune sensing. As the analyte concentration increased, the Fe 3 O 4 @MoS 2 probe could generate dual-mode signals, including remarkable color changes from the chromogenic substrate oxidation as well as photothermal enhancement. Moreover, to avoid false negative results, the excellent magnetic capability of the Fe 3 O 4 @MoS 2 probe can be used to pre-enrich the trace analytes, amplifying the detection signal and enhancing the immunoassay's sensitivity. Under optimal conditions, specific and rapid detection of SARS-CoV-2 has been realized successfully based on this integrated nanoprobe-enhanced CLISA platform. The detection limits were 5.41 pg·mL -1 for the photothermal assay and 150 pg·mL -1 for the visual colorimetric assay. More importantly, the simple, affordable, and portable platform can also be expanded to rapidly detect other targets such as Staphylococcus aureus and Salmonella typhimurium in practical samples, making it a universal and attractive tool for multiple pathogen analysis and clinical testing in the post COVID-19 era.

Although continuous monitoring of constituents in complex sweat is crucial for noninvasive physiological evaluation, biofouling on the sweat sensor surface and inadequate flexible self-healing materials restrict its applications. Herein, a fully self-healing and strong anti-biofouling polypeptide complex hydrogel (AuNPs/MoS 2 /Pep hydrogel) with excellent electrochemical performances was created. The anti-fouling electrochemical sweat sensor was fabricated based on the AuNPs/MoS 2 /Pep hydrogel to address these issues. It was found that the polypeptide hydrogel was designed to form a network structure and carried abundant hydrophilic groups, resulting in a AuNPs/MoS 2 /Pep hydrogel with superior anti-biofouling properties in sweat for 30 min and even long-term stability in undiluted human sweat. In addition, SEM, TEM, UV, XPS, and infrared spectrogram demonstrated that the binding force of π-π stacking force between MoS 2 and naphthalene groups in the designed peptide endowed the polypeptide complex hydrogel with an excellent self-healing property. Furthermore, the polypeptide complex hydrogel preserved wearable device function of continuously monitoring uric acid (UA) and ascorbic acid (AA) in sweat in situ. This novel fabricated sweat sensor with high anti-biofouling ability, excellent self-healing property, and sensitive and selective analytical capability describes a new opportunity for health monitoring in situ.

Molybdenum-based nanomaterials have shown promise for anticancer treatment due to their strong photothermal and redox-activated capabilities. Herein, we have fabricated cerium-doped MoO x (Ce-MoO v ) with tunable Mo/Ce molar ratios by a one-pot method and investigated their effect on chemodynamic therapy (CDT) and photothermal therapy (PTT). It is found that Ce-MoO v can self-assemble into nanoclusters in acidic conditions and the increasing Ce amount will generate oxygen vacancy defects and induce the valence change of Mo 6+ /Mo 5+ and Ce 4+ /Ce 3+ , which leads to strong near-infrared absorption with high photothermal conversion efficiency of 71.31 and 49.86% for 808 and 1064 nm. Other than photothermal conversion, the materials demonstrate pH-/glutathione (GSH)-activated photoacoustic (PA) imaging capability in vitro . In addition, Ce-MoO v acts as a CDT reagent capable of converting endogenous H 2 O 2 to two types of reactive oxygen species ( • OH, 1 O 2 ) while depleting GSH. Ce-MoO v demonstrates an excellent therapeutic effect against HCT116 cells and effectively reduces the intracellular GSH level and significantly increases the number of reactive radicals under 1064 nm laser irradiation as compared with the no-laser group in vitro . This work provides a new paradigm using lanthanide-doped polymetallic oxides for pH-/GSH-responsive photothermal/chemodynamic therapy with PA imaging ability.

Bacterial infections caused by pathogenic bacteria are extremely threatening to human health. Currently, the treatment of bacterial infections relies heavily on antibiotics, leading to a high incidence of antibiotic abuse. Bacterial resistance appeared along with the misuse of antibiotics that produced growing harm to human beings. Therefore, a cutting-edge strategy for treating bacterial infections is indeed needed. Here we prepared QCuRCDs@BMoS 2 nanocomposites (QBs) for an efficient bacterial trapping and triple quaternary ammonium salt/photothermal/photodynamic bactericidal method. Copper-doped carbon quantum dots were first prepared by using a solvothermal method, modified with quaternary ammonium salts, and then combined with grafted MoS 2 nanoflowers. The long alkyl chains of QBs and the sharp surface of MoS 2 facilitate the destruction of bacterial structures, while the electrostatic adsorption binds closely to bacteria, shortening the bactericidal distance of the reactive oxygen species (ROS). Moreover, the excellent photothermal performance under 808 nm irradiation in the near-infrared (NIR) region and deep penetrating heat can accelerate oxidative stress and achieve a multisynergistic bactericidal purpose. Consequently, QBs with ideal antibacterial properties and inherent brightness hold great promise in the biomedical field.

Transition metal sulfides have exhibited remarkable advantages in gaseous elemental mercury (Hg 0 ) capture under high SO 2 atmosphere, whereas the weak thermal stability significantly inhibits their practical application. Herein, a novel N , N -dimethylformamide (DMF) insertion strategy via crystal growth engineering was developed to successfully enhance the Hg 0 capture ability of MoS 2 at an elevated temperature for the first time. The DMF-inserted MoS 2 possesses an edge-enriched structure and an expanded interlayer spacing (9.8 Å) and can maintain structural stability at a temperature as high as 272 °C. The saturated Hg 0 adsorption capacities of the DMF-inserted MoS 2 were measured to be 46.91 mg·g -1 at 80 °C and 27.40 mg·g -1 at 160 °C under high SO 2 atmosphere. The inserted DMF molecules chemically bond with MoS 2 , which prevents possible structural collapse at a high temperature. The strong interaction of DMF with MoS 2 nanosheets facilitates the growth of abundant defects and edge sites and enhances the formation of Mo 5+ /Mo 6+ and S 2 2- species, thereby improving the Hg 0 capture activity at a wide temperature range. Particularly, Mo atoms on the (100) plane represent the strongest active sites for Hg 0 oxidation and adsorption. The molecule insertion strategy developed in this work provides new insights into the engineering of advanced environmental materials.

Among the many metal-dinitrogen complexes synthesized, the end-on bridging (μ2, η ¹, η¹--N2) coordination mode is notoriously unreactive for nitrogen fixation. This is principally due to the large activation energy for ground-state nitrogen-element bond formation and motivates exploration of the photoexcited reactivity of this coordination mode. To provide the foundation for this concept, the photophysics of a dinitrogen-bridged molybdenum complex was explored by ultrafast electronic spectroscopies. The complex absorbs light from the UV to near-IR, and the transitions are predominantly of metal-to-ligand charge transfer (MLCT) character. Five excitation wavelengths (440, 520, 610, 730, and 1150 nm) were employed to access MLCT bands, and the dynamics were probed between 430 and 1600 nm. Despite the large energy space occupied by electronic states (ca. 1.2 eV), the dynamics were independent of the excitation wavelength. In the proposed kinetic model, photoexcitation from a Mo-N=N-Mo centered ground state populates the π[sup *]-state delocalized over two terpyridine ligands. Due to a large terpyridine-terpyridine spatial separation, electronic localization occurs within 100 fs, augmented by symmetry breaking. The subsequent interplay of internal conversion and intersystem crossing (ISC) populates the lowest ³MLCT state in 2-3 ps. Decay to the ground state occurs either directly or via a thermally activated metal-centered (³MC) trap state having two time constants (10-15 ps, 23-26 ps [298 K]; 103 ps, 612 ps [77 K]). ISC between ¹MLCT and ³MLCT involves migration of energized electron density from the terpyridine π[sup *] orbitals to the Mo-N=N-Mo core. Implication of the observed dynamics for the potential N-H bond forming reactivity are discussed. [ABSTRACT FROM AUTHOR]

The controlled synthesis of large-area, atomically thin molybdenum and tungsten ditelluride (MoTe2 and WTe2) crystals is crucial for their emerging applications based on the attractive electronic properties. However, the solution phase synthesis of high-quality and large-area MoTe2 or WTe2 ultrathin films have not been achieved yet. In this study, we synthesized for the first time, large-area atomically thin MoTe2 and WTe2 films in solution phase, through rapid crystal formation directly on a conducting substrate. For the synthesis, we developed a new Te precursor. The crystal growth involves an in situ chemical transformation from Te nanoparticles into MoTe2 or WTe2 thin films. The synthesis enables precise control of the number of atomic layers over a large area, from a monolayer to multilayers. Micropatterned MoTe2 thin films are also readily synthesized in situ using the same process. The photodetector made of 3-layer semiconducting MoTe2 thin films exhibits high photoresponsivity (Rλ) over a broad spectral range (300-1100 nm) with a maximum in the near-IR region, including a Rλ = 30 mA W-1 even at λ = 1.10 μm and a fast photoresponse (87 μs). Our synthesis method presents a crucial step in the solution phase synthesis of metal telluride ultrathin films and paves the way for their large-scale emerging applications. [ABSTRACT FROM AUTHOR]

MnMoO4 microcrystals were synthesized by hydrothermal methods, and their structural, morphological, and vibrational properties were investigated. Conventional reactors and microwave-heated hydrothermal vessels were used to synthesize micrometer-sized MnMoO4polymorphs at different temperature and time conditions. MnMoO4•H2O crystals were obtained in both reactors at temperatures below 200 °C, for times up to 24 h. These microcrystals belong to the triclinic P1̅ space group, and their 26 characteristic Raman bands were identified. A monoclinic MnMoO4 polymorph belonging to the P2/c structure was synthesized at temperatures higher than 200 °C only into conventional hydrothermal reactors. Polarized micro-Raman analyses have evidenced and allowed the assignment of 18 phonon modes predicted by group-theory calculations for this polymorph. Another MnMoO4 polymorph, within the monoclinic C2/m space group, was obtained by two processing routes: (i) heating the P2/c microcrystals at 600 °C; or (ii) heating the MnMoO4•H2O phase at 250 °C. For this monoclinic phase, 33 Raman-active bands were identified and assigned, in very good agreement with group-theoretical calculations, which predict 36 modes for the C2/m polymorph. Well-faceted, highly crystalline microcrystals were clearly observed by scanning and transmission electron microscopies, in perfect agreement with X-ray diffraction and Raman spectroscopic analysis. Finally, the appearance of characteristic phonon modes related to molybdenum in octahedral coordination suggests an incipient crystallization of a new, unreported α-MnMoO4 polymorph, at least in a short-range degree. [ABSTRACT FROM AUTHOR]

Red-emitting phosphors with the general sum formula Sr8[Li(2-0.5x)MgxAl(22-0.5x)N28]:Eu2+ for application in warm-white illumination grade light emitting diodes were obtained by reacting the metals, hydrides, and nitrides in molybdenum crucibles in a hot isostatic press. Upon irradiation with blue light (440 nm), the materials exhibit red luminescence (emission maximum: 633-665 nm; full width at half-maximum (fwhm): 1736-1964 cm-1, 78-82 nm) tunable by adjusting the compositional variable x (here, 2 and 4) as well as the activator concentration (here, 0.075-1 atom-% Eu2+). The materials show promising thermal behavior of the emission with relative quantum efficiencies, compared to room temperature, of 66% (x = 0) and 84% (x = 2) at 200 °C. α-Sr8[Li(2-0.5x)MgxAl(22-0.5x)N28]:Eu2+ (x = 2 and 4) crystallizes isotypically with Sr4[LiAl11N14]:Eu2+ in the orthorhombic space group Pnnm (no. 58) with unit cell parameters a = 10.51818(5)-10.54878(6), b = 10.44513(5)-10.48253(6), and c = 3.25704(1)-3.272752(15) Å. β-Sr2[MgAl5N7]:Eu2+ (x = 4) crystallizes in the monoclinic space group C2/m (no. 12) with unit cell parameters a = 11.12874(11), b = 3.27289(3), c = 10.54530(11) Å, and β = 109.8939(7)° and is obtained as side phase (≤40 wt %) in syntheses with x = 4. The crystal structure of β-Sr2[MgAl5N7]:Eu2+ consists of a network of vertex- and edge-sharing Al(/Mg)N4 tetrahedra with four- and five-membered ring channels along [010]. The Sr2+ ions are located within the five-membered ring channels and are coordinated cube-like by eight N atoms. [ABSTRACT FROM AUTHOR]

Single-crystal transition metal dichalcogenides (TMDs) and TMD-based heterojunctions have recently attracted significant research and industrial interest owing to their intriguing optical and electrical properties. However, the lack of a simple, low-cost, environmentally friendly, synthetic method and a poor understanding of the growth mechanism post a huge challenge to implementing TMDs in practical applications. In this work, we developed a novel approach for direct formation of high-quality, monolayer and few-layer MoS2 single crystal domains via a single-step rapid thermal processing of a sandwiched reactor with sulfur and molybdenum (Mo) film in a confined reaction space. An all-solid-phase growth mechanism was proposed and experimentally/theoretically evidenced by analyzing the surface potential and morphology mapping. Compared with the conventional chemical vapor deposition approaches, our method involves no complicated gas-phase reactant transfer or reactions and requires very small amount of solid precursors [e.g., Mo (∼3 μg)], no carrier gas, no pretreatment of the precursor, no complex equipment design, thereby facilitating a simple, low-cost, and environmentally friendly growth. Moreover, we examined the symmetry, defects, and stacking phase in as-grown MoS2 samples using simultaneous second-harmonic-/sum-frequency-generation (SHG/SFG) imaging. For the first time, we observed that the SFG (peak intensity/position) polarization can be used as a sensitive probe to identify the orientation of TMDs’ crystallographic axes. Furthermore, we fabricated ferroelectric programmable Schottky junction devices via local domain patterning using the as-grown, single-crystal monolayer MoS2, revealing their great potential in logic and optoelectronic applications. Our strategy thus provides a simple, low-cost, and scalable path toward a wide variety of TMD single crystal growth and novel functional device design. [ABSTRACT FROM AUTHOR]

Doping with a transition metal was recently shown to greatly boost the activity and durability of PtNi/C octahedral nanoparticles (NPs) for the oxygen reduction reaction (ORR), but its specific roles remain unclear. By combining electrochemistry, ex situ and in situ spectroscopic techniques, density functional theory calculations, and a newly developed kinetic Monte Carlo model, we showed that Mo atoms are preferentially located on the vertex and edge sites of Mo-PtNi/C in the form of oxides, which are stable within the wide potential window of the electrochemical cycle. These surface Mo oxides stabilize adjacent Pt sites, hereby stabilizing the octahedral shape enriched with (111) facets, and lead to increased concentration of Ni in subsurface layers where they are protected against acid dissolution. Consequently, the favorable Pt3Ni(111) structure for the ORR is stabilized on the surface of PtNi/C NPs in acid against voltage cycling. Significantly, the unusual potential-dependent oxygen coverage trend on Mo-doped PtNi/C NPs as revealed by the surface-sensitive Δµ analysis suggests that the Mo dopants may also improve the ORR kinetics by modifying the coordination environments of Pt atoms on the surface. Our studies point out a possible way to stabilize the favorable shape and composition established on conceptual catalytic models in practical nanoscale catalysts. [ABSTRACT FROM AUTHOR]

Positional and stereochemical selectivity in the isomerization of terminal alkenes to internal alkenes is observed using the cis-Mo(CO)4(PPh3)2 precatalyst. A p-toluenesulfonic acid (TsOH) cocatalyst is essential for catalyst activity. Various functionalized terminal alkenes have been converted to the corresponding 2-alkenes, generally favoring the Z isomer with selectivity as high as 8:1 Z:E at high conversion. Interrogation of the catalyst initiation mechanism by 31P NMR reveals that cis-Mo(CO)4(PPh3)2 reacts with TsOH at elevated temperatures to yield a phosphine-ligated Mo hydride (MoH) species. Catalysis may proceed via 2,1-insertion of a terminal alkene into a MoH group and stereoselective β-hydride elimination to yield the (Z)-2-alkene. [ABSTRACT FROM AUTHOR]

In this work, the recovery of molybdenum(VI) (Mo) from aqueous solutions was carried out by solvent extraction (SX) using ammonium and phosphonium-based task-specific ionic liquids (TSILs) as extractants diluted in kerosene and two other hydrophobic room-temperature ionic liquids (RTILs). Four different TSILs were used as extractants: trioctylmethylammonium bis(2-ethylhexyl) phosphate [TOMA][D2EHP]; trioctylmethylammonium benzoate [TOMA][BA]; trihexyltetradecylphosphonium bis(2-ethylhexyl) phosphate [P6,6,6,14][D2EHP]; and trihexyltetradecylphosphonium benzoate [P6,6,6,14][BA]. These TSILs were synthesized to assess the effect of the cation and anion on the SX of Mo(VI). Experimental results indicated that high extraction percentages of Mo(VI) were obtained with all the synthesized TSILs. Besides that, the best cation was [TOMA]+ for all the diluents and [BA]- was the best anion when kerosene and 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [omim][Tf2N], were the diluents. Furthermore, the SX process using these ionic liquids followed an anion-exchange mechanism for kerosene and [omim][Tf2N] as diluents. Finally, the stripping was successfully performed with a solution of ammonium carbonate, and the extent of stripping depended on the selected diluent. [ABSTRACT FROM AUTHOR]

The article states the first preparation of NiMo layered double hydroxide (LDH) adsorbent for the removal of dibenzothiophene (DBT) form n-heptane solution and desulfurization of gas oil. The existence of (Mo6+) in Ni2+Mo6+ LDH was proven by X-ray photoelectron spectroscopy (XPS), while X-ray diffraction and X-ray fluorescence patterns, Fourier transform infrared spectra, scanning electron microscopy images, and differential scanning calorimetry-thermogravimetric analysis and Brunauer-Emmett-Teller analysis were applied for the composition and surface characterizations. Experimentally, NiMo LDH exhibited a different conduct in the adsorption elimination of sulfur in the existence of aromatics; the sulfur uptake was increased with the increase of the aromatic content in accordance with its own highly charged surface as a result of the formation of +4 balancing charges between Ni2+ and Mo6+ through the brucite layers. The material achieved adsorption capacity of 48.8 mg g-1 sulfur for DBT at 25 °C follows a pseudo-second-order kinetic type and Langmuir isotherm. NiMo LDH adsorbent showed a remarked desulfurization of gas oil by 79.6%, although it has a high aromatic content (33%). A p-complexation between the Ssulfur atoms and Mo6+ was proposed through surface adsorption. The material conserved its parental structure and adsorptive activity after being regenerated seven times. [ABSTRACT FROM AUTHOR]

Strain serves as a powerful freedom to effectively, reversibly, and continuously engineer the physical and chemical properties of two-dimensional (2D) materials, such as bandgap, phase diagram, and reaction activity. Although there is a high demand for full characterization of the strain vector at local points, it is still very challenging to measure the local strain amplitude and its direction. Here, we report a novel approach to monitor the local strain vector in 2D molybdenum diselenide (MoSe2) by polarization-dependent optical second-harmonic generation (SHG). The strain amplitude can be evaluated from the SHG intensity in a sensitive way (-49% relative change per 1% strain); while the strain direction can be directly indicated by the evolution of polarization-dependent SHG pattern. In addition, we employ this technique to investigate the interlayer locking effect in 2H MoSe2 bilayers when the bottom layer is under stretching but the top layer is free. Our observation, combined with ab initio calculations, demonstrates that the noncovalent interlayer interaction in 2H MoSe2 bilayers is strong enough to transfer the strain of at least 1.4% between the bottom and top layers to prevent interlayer sliding. Our results establish that SHG is an effective approach for in situ, sensitive, and noninvasive measurement of local strain vector in noncentrosymmetric 2D materials. [ABSTRACT FROM AUTHOR]

Reduced pyridine(diimine) molybdenum olefin complexes have been synthesized and structurally characterized. Examples with 1,5-cyclooctadiene, (PDI)Mo(η2:η2-1,5-COD) (COD = 1,5-cyclooctadiene) adopt a distorted-trigonal-bipyramidal geometry and are best described as low-spin Mo(II) compounds arising from significant π back-donation to the ligand from a reduced molybdenum center. With the 2,6-diisopropyl N-aryl-substituted variant of the pyridine(diimine) ligand, a molybdenum bis(ethylene) complex was obtained. Reducing the size of the N-aryl substituents to 2,4,6-trimethyl resulted in isolation of (MesPDI)Mo(η4-butadiene)(η2-ethylene) following sodium amalgam reduction of the corresponding molybdenum(III) trichloride complex in the presence of excess ethylene. Analysis of the byproducts of the reaction and olefin addition experiments demonstrate that butadiene formation is consistent with a pathway involving ethylene coupling to form 1-butene followed by allylic dehydrogenation to produce butadiene. Excess ethylene serves as the hydrogen acceptor. The dehydrogenation reaction was also compatible with α-olefins, as reduction of either (iPrPDI)MoCl3 or (MesPDI)MoCl3 in the presence of 1-hexene resulted in isolation of (PDI)Mo(η4-1,3-hexadiene)(η2-1-hexene) complexes. An α,ω-diene complex, (iPrPDI)Mo(η2:η2-1,6-heptadiene), was also synthesized and importantly displayed no cycloaddition chemistry, suggesting that first-row metal pyridine(diimine) complexes are thus far unique in promoting cyclobutane synthesis. [ABSTRACT FROM AUTHOR]

Reactions between Mo(N-t-Bu)2(CH2-t-Bu)2 or Mo(NAdamantyl)2(CH2CMe2Ph)2 and 3 equiv of HCl in the presence of 1 equiv of PPh2Me yield Mo(NR)(CHR')(PPh2Me)Cl2 complexes, from which Mo(NR)(CHR')(PPh2Me)(OAr)Cl complexes (OAr = a 2,6-terphenoxide) can be prepared. The Mo(NR)(CHR')(PPh2Me)(OAr)Cl complexes were evaluated as cross-metathesis catalysts between cyclooctene and Z-1,2-dichloroethylene. The efficiencies of the test reaction for complexes in which OAr = OTPP, OHMT, OHIPT, or OHTBT (where OTPP is 2,3,5,6-tetraphenylphenoxide, OHMT is hexamethylterphenoxide, OHIPT is hexaisopropylterphenoxide, and OHTBT is hexa-t-butylterphenoxide) maximize when OAr is OHMT or OHIPT. Mo(N-t-Bu)(CH-t-Bu)(PPh2Me)Cl2 is essentially inactive for the reaction between cyclooctene and Z-1,2-dichloroethylene. X-ray structural studies were carried out on Mo(NAd)(CHCMe2Ph)(PPh2Me)Cl2, Mo(N-t-Bu)(CH-t-Bu)(PPh2Me)(OHMT)Cl, Mo(NAd)(CHCMe2Ph)(Cl)(OHTBT)(PMe3), and [Mo(NAd)(CHCMe2Ph)(PMe3)(Cl)]2(μ-O), the product of the reaction between Mo(NAd)(CHCMe2Ph)(Cl)(OHTBT)(PMe3) and 0.5 equiv of water. [ABSTRACT FROM AUTHOR]

Molybdenum (Mo) is an essential trace nutrient but has negative health effects at high concentrations. Groundwater typically has low Mo (<2 μg/L), and elevated levels are associated with anthropogenic contamination, although geogenic sources have also been reported. Coal combustion residues (CCRs) are enriched in Mo, and thus present a potential anthropogenic contamination source. Here, we use diagnostic geochemical tracers combined with groundwater residence time indicators to investigate the sources of Mo in drinking-water wells from shallow aquifers in a region of widespread CCR disposal in southeastern Wisconsin. Samples from drinking-water wells were collected in areas near and away from known CCR disposal sites, and analyzed for Mo and inorganic geochemistry indicators, including boron and strontium isotope ratios, along with groundwater tritium-helium and radiogenic 4He ingrowth age-dating techniques. Mo concentrations ranged from <1 to 149 μg/L. Concentrations exceeding the U.S. Environmental Protection Agency health advisory of 40 μg/L were found in deeper, older groundwater (mean residence time >300 y). The B (δ11B = 22.9 ± 3.5%0 and Sr (87Sr/86Sr = 0.70923 ± 0.00024) isotope ratios were not consistent with the expected isotope fingerprints of CCRs, but rather mimic the compositions of local lithologies. The isotope signatures combined with mean groundwater residence times of more than 300 years for groundwater with high Mo concentrations support a geogenic source of Mo to the groundwater, rather than CCR-induced contamination. This study demonstrates the utility of a multi-isotope approach to distinguish between fossil fuel-related and natural sources of groundwater contamination. [ABSTRACT FROM AUTHOR]

The Ni, Ni-Mo, Ni-Mg, and Ni-Mo-Mg catalysts were systematically explored for the one-step conversion of polystyrene (PS) into carbon nanotubes (CNTs). The catalysts were characterized in the phase structure, morphology, reducibility, and carbonization performance. It was found that the Mo contributed to the small catalyst particle growth by the formation of NiMoO4 phase. The addition of Mg had no effect on catalyst particle sizes but effectively controlled the carbon solubility and led to the growth of CNTs by the generation of NiMgO2. Finally, we demonstrated that the Ni-Mo-Mg catalysts showed the most efficient for the conversion of PS into CNTs owing to the individually synergetic effect of Mo and Mg elements. Besides catalysts, the degradation additives and the carbonization temperature were also discussed for their effects on the carbonization of PS. It is believed that the work provides potential for the conversion of PS waste into CNTs. [ABSTRACT FROM AUTHOR]

Molybdenum-99 is the parent isotope of the most widely used isotope, technetium-99m, in all diagnostic nuclear medicine procedures. Due to proliferation concerns associated with the use of highly enriched uranium (HEU), the preferred method of fission-based Mo-99 production uses low enriched uranium (LEU) targets. Using LEU versus HEU for Mo-99 production produces ~30 times more Pu-239, due to neutron capture on U-238 to produce Np-239, which ultimately decays to Pu-239 (t1/2 = 24,110 yr). Argonne National Laboratory is supporting a potential US Mo-99 producer in their efforts to produce Mo-99 from an LEU solution. In order to mitigate the generation of large volumes of greater-than-class-C (GTCC) low level waste (Pu-239 concentrations greater than 1 nCi/g), we have focused our efforts on the separation chemistry of Pu and Mo with a titania sorbent in sulfate media. Results from batch and column experiments show that temperature and acid wash concentration can be used to control Pu behavior on titania. [ABSTRACT FROM AUTHOR]

A novel domino reduction/imine formation/intramolecular cyclization/oxidation for the efficient synthesis of pyrrolo(indolo)[1,2-a]quinoxalines and pyrrolo(indolo)[3,2-c]-quinolines from readily available nitrobenzenes and glycols is reported. The process utilizes the carbonyl byproduct of the initial dioxomolybdenum(VI)-catalyzed reduction of nitroaromatics with glycols as a reagent for the imine generation. This method represents the first sustainable domino reaction for the preparation of biologically relevant heterocycles that internally incorporates the waste formed in the first step to the final product. [ABSTRACT FROM AUTHOR]