Search

Koppar (Cu) har en avgörande roll i flera viktiga metaboliska funktioner och är en essentiell mineral för idisslare. Kopparbrist kan resultera i ett flertal problem som påverkar djurets hälsa och produktion, men även överutfodring av Cu kan resultera i allvarliga kliniska symptom på grund av ackumulering av Cu i levern. Utöver detta är kopparmetabolismen hos idisslare mer komplex än hos enkelmagade djur. I våmmen sker interaktioner som minskar tillgängligheten av Cu. Den huvudsakliga antagonisten är mineralen molybden (Mo) som tillsammans med svavel (S) binder till Cu och skapar olösliga komplex. Det finns ett starkt samband mellan Mo i jorden och Mo i växter. I områden med höga halter av Mo i jorden resulterar detta även i foder med höga koncentrationer av Mo. Detta kompenseras ofta med extra utfodring av Cu, vilket gör det viktigt med övervakning av kopparstatus i besättningarna. Den huvudsakliga metoden för att övervaka kopparstatus hos besättningar idag är genom leverprover, antingen biopsier eller prover tagna i samband med slakt. Syftet med den här masteruppsatsen var att utvärdera kopparstatus i relation till intag av Cu och Mo i foder hos mjölkkobesättningar runt Falköping i Sverige där områden med höga koncentrationer av Mo i jorden finns. Det var även meningen att utvärdera om prover på päls är en lämplig metod för att övervaka kopparstatus, då provtagning av lever är komplext och kan vara ekonomiskt kostsamt. Tio mjölkgårdar valdes ut baserat på koncentration av Mo i deras egenodlade grovfoder. Fem gårdar med molybdenkoncentration ≤ 1.2 mg/kg TS (LOW) och fem gårdar med molybdenkoncentration ≥ 5 mg/kg TS (HIGH). På varje gård togs pälsprover från fem slumpmässigt utvalda lakterande kor och leverprover togs från de upp till sex första korna som skickades till slakt efter gårdsbesöket. Alla prover skickades till ett laboratorium för analys av kopparkoncentration. Utöver det så mättes bröstomfånget på alla djur som provtogs för päls och en uppskattning av da, With its’ vital roll in several important metabolic functions, copper (Cu) is an essential mineral for ruminants. Deficiency can cause a variety of problems affecting the animals’ health and production, but excess of Cu can also result in severe clinical symptoms because of its’ accumulation in the liver. In addition to this, Cu metabolism is particularly complex in ruminants compared to monogastric animals. In the rumen interactions that decrease Cu availability occurs. The main antagonist is the mineral molybdenum (Mo) which toghether with sulphur (S) bind to Cu and form insoluble precipitates. There is a strong correlation between Mo in soil and Mo in crops. In geochemical areas high of Mo, this results in feed with high concentrations of Mo which need to be compensated with extra supplementat of dietary Cu, making monitoring of Cu status important. The main method for monitoring of Cu status today is liver samples, either biopsies or samples taken at slaughter. The aim of this master thesis was therefore to evaluate Cu status in relation to dietary intake of Cu and Mo of dairy herds located around Falköping, Sweden, where geochemical areas with high Mo in soil exists. And also to evaluate if fur samples is an adequate method to monitor Cu status, since taking liver samples are complex and can be costly. Ten dairy farms where selected based on Mo concentration in homegrown roughage. Five farms with Mo concentration ≤ 1.2 mg/kg DM (LOW) and five farms with Mo concentrations ≥ 5 mg/kg DM (HIGH). On all farms, five random lactating animals were sampled for fur, however liver samples were taken from the first up to six animals sent to slaughter after farm visits. All samples were sent to a laboratory and analysed for Cu concentration. In addition, chest circumference was measured on the fur sampled animals and an estimation of daily feed intake including all feed components and feed analyses were made in order to do an one-day feeding control, a control to evaluate n

Koppar (Cu) är ett essentiellt spårämne med flertalet funktioner hos idisslare men både över- och underutfodring kan ha negativa effekter på djurets hälsa och produktion. Utöver det interagerar Cu med andra mineraler i våmmen vilket minskar tillgängligheten av Cu i tunntarmen. En av de mest avgörande antagonisterna för kopparupptag är molybden (Mo) som tillsammans med svavel (S) binder till Cu och bildar olösliga komplex. Molybden överförs från jord till gräs vilket resulterar i höga molybdenkoncentrationer i foder som är skördat från molybdenrika jordar. Högplatåerna kring Falköping är ett sådant område och för att motverka den inhiberande effekten av Mo tillförs extra Cu till mjölkkofoderstater i området. Idag är leverprover den vanligaste metoden för att utvärdera kopparstatus, antingen från leverbiopsi eller från slaktade djur. En metod för att utvärdera Cu status som kan implementeras i rutinskötsel av mjölkkor i områden med molybdenrika jordar hade varit ett viktigt verktyg för att säkerställa korrekt utfodring av Cu. Målet med denna studie var därför att utvärdera och jämföra kopparstatus på mjölkbesättningar i Falköpingsområdet med höga och låga molybdenkoncentrationer i fodret. Fokus i detta masterarbete var på Cu som utsöndras via träck, urin och mjölk då dessa metoder skulle vara möjligt att genomföra som del av rutinskötsel i mjölkkobesättningar. 10 mjölkgårdar i Västra Götaland valdes ut för att delta i studien baserat på molybdenkoncentrationen i hemodlat grovfoder. 5 av gårdarna hade högt (HI) molybdeninnehåll (≥ 5 mg Mo/kg ts) och 5 av gårdarna hade lågt (LO) molybdeninnehåll (≤ 1.2 mg Mo/kg ts) i grovfodret. På varje gård provtogs 5 kor på träck, urin och mjölk. Proverna analyserades för kopparkoncentration. Utöver detta provtogs även allt hemodlat foder för mineralinnehåll och en endagars foderstatskontroll genomfördes för att skatta dagligt foderintag, inklusive mineraler. Kopparkoncentrationen i proverna jämfördes med intag samt analyserades för, Copper (Cu) is an essential trace mineral with several important functions in ruminants, but both under- and over feeding of Cu can have negative effects on the animals health and production. In addition, Cu interacts with other mineral elements in the rumen, which decrease the Cu availability in the small intestine. One of the major antagonists of Cu uptake is molybdenum (Mo) which together with sulphur (S) binds to Cu, forming insoluble complexes. Molybdenum is transferred from soil to crops which results in high Mo concentrations in feed harvested from Mo rich soils. The high plateaus around Falköping, Sweden, is an area with high Mo soils. To compensate for the inhibitory effect of Mo, extra supplementary Cu is included in the rations to dairy cows in the area. At present, the most common method for assessing Cu status is analysis of liver samples, either as liver biopsy or from slaughtered animals. A method for monitoring Cu status which could be implemented into routine management of dairy herds in high Mo areas would be an important tool to ensure correct supplementation of Cu. The objective of this study was therefore to evaluate and compare Cu status in dairy herds located in the area around Falköping, Sweden, with high or low Mo concentrations in the feed. Focus in this master thesis was on Cu excreted in faeces, urine and milk as these methods could be relatively easy to implement in routine management of dairy herds. 10 dairy farms in Västra Götaland, Sweden, were chosen for the study based on the Mo levels in their home grown forage. 5 farms had high (HI) levels of Mo (≥ 5 mg Mo/kg DM) and 5 farms had low (LO) levels of Mo (≤ 1.2 mg Mo/kg DM) in their forage. On each farm 5 lactating cows were sampled for faeces, urine and milk and the samples were analysed for Cu concentration. In addition, feedstuffs produced on the farm were analysed for mineral content and a one day feeding control was performed to estimate daily feed intake, including mineral intak

A key problem in ion-solid interaction is the lack of experimental access to the dynamics of the processes. While it is clear that the mechanisms of interaction and sputtering depend on the kinetic and potential energy (sum of ionization energies) of the projectile, the importance and interplay of the various interaction mechanisms are unknown. Here, we have irradiated substrate-supported (Au, SiO2) monolayers of MoS2 with highly charged xenon ions (HCIs; charge state: 17+ to 40+), extracted the emitted neutral postionized Mo particles in a time-of-flight mass spectrometer, and determined their velocity distributions. We find two main contributions, one at high velocities and a second at lower velocities, and assign them to kinetic and potential effects, respectively. We show that for slow HCIs (5 keV) the interaction mechanisms leading to particle emission by electronic excitation and momentum transfer, respectively, are independent of each other, which is consistent with our atomistic simulations. Our data suggest that the predominant mechanism for potential sputtering is related to electron-phonon coupling, while nonthermal processes do not play a significant role. We anticipate that our work will be a starting point for further experiments and simulations to better understand the interplay of processes arising from Epot and Ekin.

Crop requires proper plant nutrition; one of the most important factors governing plant growth and development is the integrated supply of micronutrients and macronutrients in adequate amounts and appropriate proportions; although micronutrients are required in minute quantities, they play an important role in plant growth. Micronutrients must be used wisely in crop production to ensure the optimum output of high-quality products. Plant metabolism, nutrition management, chlorophyll synthesis, reproductive growth, flower retention, and fruit and seed development are all performed by micronutrients. Boron, chlorine, copper, iron, zinc, manganese, molybdenum, and nickel are micronutrients that are required by all higher plants. Chlorine, copper, iron, and manganese are engaged in diverse photosynthetic activities, whereas zinc, copper, iron, and manganese are involved in various metabolic processes. Molybdenum is exclusively found in nitrate reductase. Boron is related with glucose metabolism, plant reproduction, photosynthesis, and enzymatic activity. The review focuses on the primary roles of micronutrients in crop development and gives an overview of recent research discoveries linked to the role of micronutrients in plants, helping to improve knowledge of their importance.

Crop requires proper plant nutrition; one of the most important factors governing plant growth and development is the integrated supply of micronutrients and macronutrients in adequate amounts and appropriate proportions; although micronutrients are required in minute quantities, they play an important role in plant growth. Micronutrients must be used wisely in crop production to ensure the optimum output of high-quality products. Plant metabolism, nutrition management, chlorophyll synthesis, reproductive growth, flower retention, and fruit and seed development are all performed by micronutrients. Boron, chlorine, copper, iron, zinc, manganese, molybdenum, and nickel are micronutrients that are required by all higher plants. Chlorine, copper, iron, and manganese are engaged in diverse photosynthetic activities, whereas zinc, copper, iron, and manganese are involved in various metabolic processes. Molybdenum is exclusively found in nitrate reductase. Boron is related with glucose metabolism, plant reproduction, photosynthesis, and enzymatic activity. The review focuses on the primary roles of micronutrients in crop development and gives an overview of recent research discoveries linked to the role of micronutrients in plants, helping to improve knowledge of their importance.

Sulfate-reducing bacteria (SRB) are obligate anaerobes that can couple their growth to the reduction of sulfate. Despite the importance of SRB to global nutrient cycles and their damage to the petroleum industry, our molecular understanding of their physiology remains limited. To systematically provide new insights into SRB biology, we generated a randomly barcoded transposon mutant library in the model SRB Desulfovibrio vulgaris Hildenborough (DvH) and used this genome-wide resource to assay the importance of its genes under a range of metabolic and stress conditions. In addition to defining the essential gene set of DvH, we identified a conditional phenotype for 1,137 non-essential genes. Through examination of these conditional phenotypes, we were able to make a number of novel insights into our molecular understanding of DvH, including how this bacterium synthesizes vitamins. For example, we identified DVU0867 as an atypical L-aspartate decarboxylase required for the synthesis of pantothenic acid, provided the first experimental evidence that biotin synthesis in DvH occurs via a specialized acyl carrier protein and without methyl esters, and demonstrated that the uncharacterized dehydrogenase DVU0826:DVU0827 is necessary for the synthesis of pyridoxal phosphate. In addition, we used the mutant fitness data to identify genes involved in the assimilation of diverse nitrogen sources and gained insights into the mechanism of inhibition of chlorate and molybdate. Our large-scale fitness dataset and RB-TnSeq mutant library are community-wide resources that can be used to generate further testable hypotheses into the gene functions of this environmentally and industrially important group of bacteria.

A personal perspective is provided regarding the work in several laboratories, including the author's, that has established the reaction mechanism of xanthine oxidase and related enzymes.

BACKGROUND: Sodium chlorate (NaClO3) is extensively used in the paper industry, but its production uses strictly regulated highly toxic Na2Cr2O7 to reach high hydrogen evolution reaction (HER) Faradaic efficiencies. It is therefore important to find alternatives either to replace Na2Cr2O7 or reduce its concentration. RESULTS: The Na2Cr2O7 concentration can be significantly reduced by using Na2MoO4 as an electrolyte co-additive. Na2MoO4 in the millimolar range shifts the platinum cathode potential to less negative values due to an activating effect of cathodically deposited Mo species. It also acts as a stabilizer of the electrodeposited chromium hydroxide but has a minor effect on the HER Faradaic efficiency. X-ray photoelectron spectroscopy (XPS) results show cathodic deposition of molybdenum of different oxidation states, depending on deposition conditions. Once Na2Cr2O7 was present, molybdenum was not detected by XPS, as it is likely that only trace levels were deposited. Using electrochemical measurements and mass spectrometry we quantitatively monitored H-2 and O-2 production rates. The results indicate that 3 mu mol L-1 Na2Cr2O7 (contrary to current industrial 10-30 mmol L-1) is sufficient to enhance the HER Faradaic efficiency on platinum by 15%, and by co-adding 10 mmol L-1 Na2MoO4 the cathode is activated while avoiding detrimental O-2 generation from chemical and electrochemical reactions. Higher concentrations of Na2MoO4 led to increased oxygen production. CONCLUSION: Careful tuning of the molybdate concentration can enhance performance of the chlorate process using chromate in the micromolar range. These insights could be also exploited in the efficient hydrogen generation by photocatalytic water splitting and in the remediation of industrial wastewater.

BACKGROUND: Sodium chlorate (NaClO3) is extensively used in the paper industry, but its production uses strictly regulated highly toxic Na2Cr2O7 to reach high hydrogen evolution reaction (HER) Faradaic efficiencies. It is therefore important to find alternatives either to replace Na2Cr2O7 or reduce its concentration. RESULTS: The Na2Cr2O7 concentration can be significantly reduced by using Na2MoO4 as an electrolyte co-additive. Na2MoO4 in the millimolar range shifts the platinum cathode potential to less negative values due to an activating effect of cathodically deposited Mo species. It also acts as a stabilizer of the electrodeposited chromium hydroxide but has a minor effect on the HER Faradaic efficiency. X-ray photoelectron spectroscopy (XPS) results show cathodic deposition of molybdenum of different oxidation states, depending on deposition conditions. Once Na2Cr2O7 was present, molybdenum was not detected by XPS, as it is likely that only trace levels were deposited. Using electrochemical measurements and mass spectrometry we quantitatively monitored H-2 and O-2 production rates. The results indicate that 3 mu mol L-1 Na2Cr2O7 (contrary to current industrial 10-30 mmol L-1) is sufficient to enhance the HER Faradaic efficiency on platinum by 15%, and by co-adding 10 mmol L-1 Na2MoO4 the cathode is activated while avoiding detrimental O-2 generation from chemical and electrochemical reactions. Higher concentrations of Na2MoO4 led to increased oxygen production. CONCLUSION: Careful tuning of the molybdate concentration can enhance performance of the chlorate process using chromate in the micromolar range. These insights could be also exploited in the efficient hydrogen generation by photocatalytic water splitting and in the remediation of industrial wastewater.

BACKGROUND: Sodium chlorate (NaClO3) is extensively used in the paper industry, but its production uses strictly regulated highly toxic Na2Cr2O7 to reach high hydrogen evolution reaction (HER) Faradaic efficiencies. It is therefore important to find alternatives either to replace Na2Cr2O7 or reduce its concentration. RESULTS: The Na2Cr2O7 concentration can be significantly reduced by using Na2MoO4 as an electrolyte co-additive. Na2MoO4 in the millimolar range shifts the platinum cathode potential to less negative values due to an activating effect of cathodically deposited Mo species. It also acts as a stabilizer of the electrodeposited chromium hydroxide but has a minor effect on the HER Faradaic efficiency. X-ray photoelectron spectroscopy (XPS) results show cathodic deposition of molybdenum of different oxidation states, depending on deposition conditions. Once Na2Cr2O7 was present, molybdenum was not detected by XPS, as it is likely that only trace levels were deposited. Using electrochemical measurements and mass spectrometry we quantitatively monitored H-2 and O-2 production rates. The results indicate that 3 mu mol L-1 Na2Cr2O7 (contrary to current industrial 10-30 mmol L-1) is sufficient to enhance the HER Faradaic efficiency on platinum by 15%, and by co-adding 10 mmol L-1 Na2MoO4 the cathode is activated while avoiding detrimental O-2 generation from chemical and electrochemical reactions. Higher concentrations of Na2MoO4 led to increased oxygen production. CONCLUSION: Careful tuning of the molybdate concentration can enhance performance of the chlorate process using chromate in the micromolar range. These insights could be also exploited in the efficient hydrogen generation by photocatalytic water splitting and in the remediation of industrial wastewater.

Essential trace elements are required in extremely small amounts and obtained through diet. This research focuses on detecting major trace elements in different biofluids of sixty women undergoing ICSI with PGT-A and SET/FET at IVI-RMA, New Jersey, and assessing their impact on their IVF outcomes. Urine, plasma, and follicular fluid samples were collected on the vaginal oocyte retrieval day to measure the concentrations of eight essential trace elements (copper, zinc, molybdenum, lithium, selenium, manganese, chromium, and iron) using ICP-MS. After analysis, ovarian response and preimplantation outcomes had significant positive associations with both copper alone and the copper/zinc ratio in the follicular fluid and plasma, in addition to plasma manganese. Alternatively, elevated follicular fluid lithium concentrations were significantly associated with poor preimplantation outcomes while the urinary molybdenum concentration was significantly associated with a lower probability of implantation, clinical pregnancy, and live birth. Urinary lithium and chromium concentrations were significantly associated with a lower probability of achieving a live birth. Our results suggest that the essential trace elements present in follicular fluid, plasma, and urine of women are directly associated with their reproductive outcomes, with copper and manganese exerting positive effects and lithium and molybdenum exerting negative effects.

The synthesis of stoichiometric two-dimensional (2D) transition-metal dichalcogenides (TMDC) over large areas remains challenging. Using a combination of X-ray diffraction and X-ray absorption spectroscopy, we demonstrate the advantages of using a thin amorphous layer of S-rich MoS2 (MoS4 in this paper) for the growth of well-ordered crystalline MoS2 films via annealing at 900 degrees C. In contrast to the crystallization of stoichiometric amorphous MoS2, the crystallization of the as-depo sited amorphous MoS4 phase shows the strong preferred ordering of layered MoS2 on a Si/SiOx nontemplating substrate with the dominant (002) crystallographic plane and accompanying Kiessig fringes, which indicate the improved crystallinity of the MoS2 layers. A similar effect can only be achieved by the templated crystallization of an amorphous MoS2 thin film deposited on a c-plane sapphire substrate. We suggest that the crystal growth improvement originates from the lower coordination number (CN) of the Mo atoms in the MoS4 amorphous phase (CN = 4) in comparison with that of amorphous MoS2 (CN = 6) and the gradual release of free sulfur atoms from the thin film during crystallization., Syntéza stechiometrických dvourozměrných (2D) dichalkogenidů přechodných kovů (TMDC) na velké plochy je stále výzvou. Pomocí kombinace rentgenové difrakce a rentgenové absorpční spektroskopie demonstrujeme výhody použití tenké amorfní vrstvy MoS2 bohatého na S (MoS4 v tomto článku) pro růst dobře uspořádaných krystalických filmů MoS2 prostřednictvím žíhání při 900 °C. Na rozdíl od krystalizace stechiometrického amorfního MoS2, krystalizace amorfní MoS4 fáze vykazuje silně preferované uspořádání vrstveného MoS2 na Si/SiOx netemplátovém substrátu s dominantní (002) krystalografickou rovinou a doprovodnými Kiessigovými oscilacemi, které indikují vylepšené uspořádání vrstev MoS2. Podobného efektu lze dosáhnout pouze templátovou krystalizací amorfního tenkého filmu MoS2 naneseného na safírovém substrátu s orientací v rovině c. Domníváme se, že zlepšení růstu krystalů je způsobeno nižším koordinačním číslem (CN) atomů Mo v amorfní fázi MoS4 (CN = 4) ve srovnání s amorfním MoS2 (CN = 6) a postupným uvolňováním volných atomů síry z tenkého filmu během krystalizace.

Lithium–sulfur (Li–S) batteries are regarded as promising candidates for high-energy storage devices because of their high theoretical energy density (2600 Wh kg−1). However, their practical applications are still hindered by a multitude of key challenges, especially the shuttle effect of soluble lithium polysulfides (LiPSs) and the sluggish sulfur redox kinetics. To address these challenges, varieties of catalytic materials have been exploited to prevent the shuttle effect and accelerate the LiPSs conversion. Recently, molybdenum-based (Mo-based) catalytic materials are widely used as sulfur host materials, modified separators, and interlayers for Li–S batteries. They include the Mo sulfides, diselenides, carbides, nitrides, oxides, phosphides, borides, and metal/single atoms/clusters. Here, recent advances in these Mo-based catalytic materials are comprehensively summarized, and the current challenges and prospects for designing highly efficient Mo-based catalytic materials are highlighted, with the aim to provide a fundamental understanding of the sulfur reaction mechanism, and to guide the rational design of cathode catalysts for high-energy and long-life Li–S batteries.

BACKGROUND: Sodium chlorate (NaClO3) is extensively used in the paper industry, but its production uses strictly regulated highly toxic Na2Cr2O7 to reach high hydrogen evolution reaction (HER) Faradaic efficiencies. It is therefore important to find alternatives either to replace Na2Cr2O7 or reduce its concentration. RESULTS: The Na2Cr2O7 concentration can be significantly reduced by using Na2MoO4 as an electrolyte co-additive. Na2MoO4 in the millimolar range shifts the platinum cathode potential to less negative values due to an activating effect of cathodically deposited Mo species. It also acts as a stabilizer of the electrodeposited chromium hydroxide but has a minor effect on the HER Faradaic efficiency. X-ray photoelectron spectroscopy (XPS) results show cathodic deposition of molybdenum of different oxidation states, depending on deposition conditions. Once Na2Cr2O7 was present, molybdenum was not detected by XPS, as it is likely that only trace levels were deposited. Using electrochemical measurements and mass spectrometry we quantitatively monitored H-2 and O-2 production rates. The results indicate that 3 mu mol L-1 Na2Cr2O7 (contrary to current industrial 10-30 mmol L-1) is sufficient to enhance the HER Faradaic efficiency on platinum by 15%, and by co-adding 10 mmol L-1 Na2MoO4 the cathode is activated while avoiding detrimental O-2 generation from chemical and electrochemical reactions. Higher concentrations of Na2MoO4 led to increased oxygen production. CONCLUSION: Careful tuning of the molybdate concentration can enhance performance of the chlorate process using chromate in the micromolar range. These insights could be also exploited in the efficient hydrogen generation by photocatalytic water splitting and in the remediation of industrial wastewater.

Salinity is the most severe abiotic stress affecting crop growth and yield worldwide. Molybdenum (Mo), a micronutrient required in small quantities by plants, has the potential to alleviate effects of stress in plants. This study aimed to determine the mechanism of Molybdenum-induce salt tolerance in Sorghum bicolor using the lowest Mo concentration. Sorghum plants grown on potting soil stressed with NaCl (0 mM - 200 mM NaCl) were treated with 0.5 and 1 µM Molybdenum [(NH4)6Mo7O24.4H2O]. NaCl reduced shoot growth and caused severe deformation in the epidermis and xylem layers of sorghum shoots, and these growth attributes were restored by Mo. While chlorophyll content was also reduced by NaCl, proline content increased by 11-fold, and these effects were also reversed by Mo. NaCl-induced oxidative damage was also reversed by Mo, resulting in significantly low levels of reactive oxygen species (ROS) in 0.5 µM Mo treated plants. NaCl also increased superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities, suggesting a high antioxidant scavenging capacity in sorghum. Mo further increased SOD activity in the roots of control and NaCl-treated plants. APX activity increased in control plants, while a decrease occurred in NaCl-treated plants upon Mo application. The HSP70 expression, which was highly induced by NaCl, was slightly reduced by 0.5 µM Mo and completely reduced by 1 µM Mo. The study concludes that low (0.5 µM) Mo concentrations effectively reduced NaCl-induced oxidative damage by regulating ROS detoxification and the expression of HSP70 thereby restoring membrane structure and improving growth

BACKGROUND: Sodium chlorate (NaClO3) is extensively used in the paper industry, but its production uses strictly regulated highly toxic Na2Cr2O7 to reach high hydrogen evolution reaction (HER) Faradaic efficiencies. It is therefore important to find alternatives either to replace Na2Cr2O7 or reduce its concentration. RESULTS: The Na2Cr2O7 concentration can be significantly reduced by using Na2MoO4 as an electrolyte co-additive. Na2MoO4 in the millimolar range shifts the platinum cathode potential to less negative values due to an activating effect of cathodically deposited Mo species. It also acts as a stabilizer of the electrodeposited chromium hydroxide but has a minor effect on the HER Faradaic efficiency. X-ray photoelectron spectroscopy (XPS) results show cathodic deposition of molybdenum of different oxidation states, depending on deposition conditions. Once Na2Cr2O7 was present, molybdenum was not detected by XPS, as it is likely that only trace levels were deposited. Using electrochemical measurements and mass spectrometry we quantitatively monitored H-2 and O-2 production rates. The results indicate that 3 mu mol L-1 Na2Cr2O7 (contrary to current industrial 10-30 mmol L-1) is sufficient to enhance the HER Faradaic efficiency on platinum by 15%, and by co-adding 10 mmol L-1 Na2MoO4 the cathode is activated while avoiding detrimental O-2 generation from chemical and electrochemical reactions. Higher concentrations of Na2MoO4 led to increased oxygen production. CONCLUSION: Careful tuning of the molybdate concentration can enhance performance of the chlorate process using chromate in the micromolar range. These insights could be also exploited in the efficient hydrogen generation by photocatalytic water splitting and in the remediation of industrial wastewater.

Even though it has been in use for a very long time, the high chromium white cast iron (HCWCI) still triggers scientists due to its outstanding wear resistance. Besides its well-known as-cast usage, it can be used as a coating material, as well. HCWCI owes this feature due to the presence of carbides in microstructure, which depends on the composition and heat treatment regime. This investigation was conducted on two HCWCI alloys, where in addition to chromium, the second important alloying element is molybdenum (Mo). Apart from other alloying elements, HCWCI_1 is alloyed with 24.48% Cr and 1.32% Mo, while HCWCI_2 contains 14.11% Cr and 2.47% Mo. The comprehensive microstructural characterization was carried out on as-cast samples and samples obtained after quenching (at -196oC) and/or quenching followed by tempering (at 250oC). Important microstructure indicators are: the stability of austenite, the ratio of microconstituents (especially different types of carbides), as well as their arrangement and morphology, so they are revealed and discussed in relation to the influencing mechanical properties.

Lithium–sulfur (Li–S) batteries are regarded as promising candidates for high-energy storage devices because of their high theoretical energy density (2600 Wh kg−1). However, their practical applications are still hindered by a multitude of key challenges, especially the shuttle effect of soluble lithium polysulfides (LiPSs) and the sluggish sulfur redox kinetics. To address these challenges, varieties of catalytic materials have been exploited to prevent the shuttle effect and accelerate the LiPSs conversion. Recently, molybdenum-based (Mo-based) catalytic materials are widely used as sulfur host materials, modified separators, and interlayers for Li–S batteries. They include the Mo sulfides, diselenides, carbides, nitrides, oxides, phosphides, borides, and metal/single atoms/clusters. Here, recent advances in these Mo-based catalytic materials are comprehensively summarized, and the current challenges and prospects for designing highly efficient Mo-based catalytic materials are highlighted, with the aim to provide a fundamental understanding of the sulfur reaction mechanism, and to guide the rational design of cathode catalysts for high-energy and long-life Li–S batteries.

Supported bimetallic molybdenum and tungsten carbides are viable replacements for noble metal catalysts and are suitable for the decarboxylation/decarbonylation and (hydro-)deoxygenation of renewable triglyceride‑based feedstocks. Here, we show that the Mo:W ratio in bimetallic carbide can steer the product yield towards either aldehydes, alcohols, alkenes or alkanes. The mixed carbides with a higher Mo/W ratio (3:1) reached higher yields of aldehydes and alcohols, while the carbides with a lower Mo/W (1:3) ratio yielded high concentrations of alkenes. Interestingly, a physical mixture of two monometallic (1 +1) carbides had a similar catalytic performance to the 1:1 mixed carbides. The intrinsic activity (turnover frequency (TOF)) of the catalysts was assessed based on both H2 and CO chemisorption. The TOFH2 related linearly with the Mo/W ratio, while the TOFCO did not show a relevant relationship. Therefore H2 chemisorption is suggested as the preferred way to assess the intrinsic activities of these catalysts.

Chemical vapor deposition (CVD) has been widely used to produce high quality 2D transitional metal dichalcogenides (2D TMDCs). However, violent evaporation and large diffusivity discrepancy of metal and chalcogen precursors at elevated temperatures often result in poor regulation on X:M molar ratio (M = Mo, W etc.; X = S, Se, and Te), and thus it is rather challenging to achieve the desired products of 2D TMDCs. Here, a modified spatially confined strategy (MSCS) is utilized to suppress the rising S vapor concentration between two aspectant substrates, upon which the lateral/vertical growth of 2D WS2 can be selectively regulated via proper S:W zones correspond to greatly broadened time/growth windows. An S:W-time (SW-T) growth diagram was thus proposed as a mapping guide for the general understanding of CVD growth of 2D WS2 and the design of growth routes for the desired 2D WS2. Consequently, a comprehensive growth management of atomically thin WS2 is achieved, including the versatile controls of domain size, layer number, and lateral/vertical heterostructures (MoS2-WS2). The lateral heterostructures show an enhanced hydrogen evolution reaction performance. This study advances the substantial understanding to the growth kinetics and provides an effective MSCS protocol for growth design and management of 2D TMDCs.

Salinity is the most severe abiotic stress affecting crop growth and yield worldwide. Molybdenum (Mo), a micronutrient required in small quantities by plants, has the potential to alleviate effects of stress in plants. This study aimed to determine the mechanism of Molybdenum-induce salt tolerance in Sorghum bicolor using the lowest Mo concentration. Sorghum plants grown on potting soil stressed with NaCl (0 mM - 200 mM NaCl) were treated with 0.5 and 1 µM Molybdenum [(NH4)6Mo7O24.4H2O]. NaCl reduced shoot growth and caused severe deformation in the epidermis and xylem layers of sorghum shoots, and these growth attributes were restored by Mo. While chlorophyll content was also reduced by NaCl, proline content increased by 11-fold, and these effects were also reversed by Mo. NaCl-induced oxidative damage was also reversed by Mo, resulting in significantly low levels of reactive oxygen species (ROS) in 0.5 µM Mo treated plants. NaCl also increased superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities, suggesting a high antioxidant scavenging capacity in sorghum. Mo further increased SOD activity in the roots of control and NaCl-treated plants. APX activity increased in control plants, while a decrease occurred in NaCl-treated plants upon Mo application. The HSP70 expression, which was highly induced by NaCl, was slightly reduced by 0.5 µM Mo and completely reduced by 1 µM Mo. The study concludes that low (0.5 µM) Mo concentrations effectively reduced NaCl-induced oxidative damage by regulating ROS detoxification and the expression of HSP70 thereby restoring membrane structure and improving growth

The functions of iron, manganese, copper, zinc, nickel, molybdenum, boron, and chlorine in plants are discussed. Iron (Fe) plays a crucial role in redox systems in cells and in various enzymes. The strategies of dicotyledonous and graminaceous plants to acquire Fe are described. Manganese (Mn) and copper (Cu) are important for redox systems and as activators of various enzymes involved in photosynthesis, detoxification of superoxide radicals, and the synthesis of lignin. Zinc (Zn) plays a key role in the structural and functional integrity of cell membranes, biosynthesis of proteins and detoxification of superoxide radicals. Nickel (Ni) is involved in nitrogen (N) metabolism as metal component of the enzyme urease. Molybdenum (Mo) is important for N metabolism as metal component of nitrogenase (N2 fixation) and nitrate reductase. Boron (B) is crucial for the stability and function of cell wall and membranes, whereas chlorine (Cl) is essential for the proper functioning of photosystem II (PS II) and cell osmotic regulation. For each micronutrient, the effects of deficiency and toxicity are described.

Shells of the fast-growing bivalve Pecten maximus serve as a geochemical archive for the reconstruction of past phytoplankton dynamics. Specifically, high-resolution, temporally accurately aligned molar barium-to-calcium (Ba/Cashell), molybdenum-to-calcium (Mo/Cashell) and lithium-to-calcium ratios (Li/Cashell) of the shell calcite revealed distinct peaks which are closely linked to phytoplankton dynamics. Yet, the development and applicability of these geochemical proxies is still at an early stage and needs further calibration. In this study, we examined the relationship between the timing and magnitude of Ba/Cashell, Mo/Cashell and Li/Cashell peaks of P. maximus and the occurrence of various phytoplankton species (diatoms and dinoflagellates) from a statistical perspective. Studied shell samples (three specimens per calendar year) as well as detailed phytoplankton observation data were derived from the well-studied costal ecosystem of the Bay of Brest (France) over three years (2011, 2012 and 2019). An algorithm-based pseudo-random sampling simulation technique was established that analyzed the complex phytoplankton datasets with respect to the profiles of Ba/Cashell, Mo/Cashell and Li/Cashell to identify potential patterns between phytoplankton and trace element time-series. The simulation results indicate that the timing and magnitude of Ba/Cashell, Mo/Cashell and Li/Cashell peaks agreed best with the occurrence of specific phytoplankton blooms that developed ca. one to two weeks earlier. The data suggest that the formation of transient Ba/Cashell peaks had a plurispecific origin, i.e., potentially linked to blooms of ingestible diatom, dinoflagellate and flagellate species enriched in Ba that occurred 8 to 12 days earlier. Observed peaks in Mo/Cashell profiles demonstrably followed the timing and intensity of blooms of the dominant dinoflagellate genus Gymnodinium spp. after a short time lag of around 8 days, potentially linked to an enhanced enzyme activity o

A concise review is provided of the contributions that various spectroscopic methods have made to our understanding of the physical and electronic structures of mononuclear molybdenum enzymes. Contributions to our understanding of the structure and function of each of the major families of these enzymes is considered, providing a perspective on how spectroscopy has impacted the field.

In the present study, we conducted experiments using wheat to elucidate whether the increased accumulation of molybdenum in leaves under nitrogen deficiency is due to the plant’s own metabolic response, and further to estimate the role of molybdenum in the nitrogen deficiency response. Even under different growth conditions such as soil culture, hydroponic culture, and aseptic culture, the nitrogen deficiency always increased the molybdenum accumulation in leaves of wheat. Because molybdenum supply to the soil enhanced the growth of wheat under nitrogen deficiency but did not increase plant nitrogen concentration, the increased molybdenum uptake might be involved in the adaptive mechanisms to nitrogen deficiency by increasing nitrogen use efficiency. Wheat under nitrogen deficiency accumulated more molybdenum in lower leaves. Moreover, the nitrogen concentration of wheat grown under nitrogen deficiency increased in the lower leaves and decreased in the upper leaves with the application of molybdenum. These results suggest that molybdenum might affect nitrogen translocation from older to younger leaves.

Some microorganisms, like the aerobic soil bacteria, Oligotropha carboxidovorans, have the capability to oxidize the highly toxic atmospheric gas carbon monoxide (CO) into CO2 through CO dehydrogenase enzymes, whose active site contains a bimetallic MoCu center. Over the last decades, a number of experimental and theoretical investigations were devoted to understanding the mechanism of CO oxidation and, in particular, the role of a very stable thiocarbonate intermediate that may be formed during the catalytic cycle. The occurrence of such an intermediate was reported to make the CO2 release step kinetically difficult. In this work, by using an accurate QM/MM approach and energy refinement by means of the BigQM method, we were able to determine the role of such an intermediate and propose a novel mechanism for the oxidation of CO into CO2 by Mo/Cu CO dehydrogenase. Surprisingly, we found that the detachment of CO2 occurs directly from the product of the Mo=O nucleophilic attack reaction on the carbon of CO aided by the transient coordination of the active site glutamate to the Mo ion. The estimated activation barrier is in good agreement with the experimental one, while the thiocarbonate turned out to not interfere with the CO-oxidation catalytic cycle. The results highlight the importance of the environmental effects in the assembly of the molecular model and in the choice of the computational protocol. Our accurate modeling of the enzyme also allowed us to exclude the involvement of a frustrated Lewis pair in the CO-oxidation mechanism, which has recently been suggested based on an analysis of structural and electronic features of synthetic mimics of the Mo/Cu CO dehydrogenase active site.

Using a potentiostatic electrodeposition technique, nanocrystalline cobalt-molybdenum (Co-Mo) superalloys containing molybdenum oxide (MoOX) were synthesized from an aqueous solution containing citric acid. Molybdenum content in the alloys was controlled up to approximately 53% by adjusting the cathode potential during the alloy electrodeposition. Based on theXRDprofiles and electron diffraction patterns, an amorphous-like nanocrystalline structure was observed in the alloys with high molybdenum content. XPS analysis revealed that the chemical state of electrodeposited molybdenum was almost metallic and the oxide state was also detected partially. According to the magnetization curves, the coercivity of electrodeposited Co-Mo alloys decreased down to approximately 72 Oe with increasing the molybdenum content up to around 53%. The microhardness reached 845 kgfmm−2 in the electrodeposited Co-53%Mo alloy and greatly exceeded that of pure cobalt (ca. 250–300 kgfmm−2). Heat resistance performance of the electrodeposited nanocrystalline Co-53%Mo alloy was improved by theMoalloying effect because the recrystallization and oxidation behavior were not observed even if the annealing temperature was increased up to 700 °C., Materials Research Express, 9(4), art. no. 046502; 2022

In the present study, we conducted experiments using wheat to elucidate whether the increased accumulation of molybdenum in leaves under nitrogen deficiency is due to the plant’s own metabolic response, and further to estimate the role of molybdenum in the nitrogen deficiency response. Even under different growth conditions such as soil culture, hydroponic culture, and aseptic culture, the nitrogen deficiency always increased the molybdenum accumulation in leaves of wheat. Because molybdenum supply to the soil enhanced the growth of wheat under nitrogen deficiency but did not increase plant nitrogen concentration, the increased molybdenum uptake might be involved in the adaptive mechanisms to nitrogen deficiency by increasing nitrogen use efficiency. Wheat under nitrogen deficiency accumulated more molybdenum in lower leaves. Moreover, the nitrogen concentration of wheat grown under nitrogen deficiency increased in the lower leaves and decreased in the upper leaves with the application of molybdenum. These results suggest that molybdenum might affect nitrogen translocation from older to younger leaves.

Tuning the reactivity of lattice oxygen is of significance for lowering the energy barriers and accelerating the oxygen evolution reaction (OER). Herein, single-atomic Mo sites are anchored on Ni–Fe oxyhydroxide nanoarrays by a facile metal–organic-framework-derived strategy, exhibiting superior performance toward the OER in alkaline media. In situ electrochemical spectroscopy and isotope-labeling experiments reveal the involvement of lattice oxygen during OER cycles. Combining theoretical and experimental investigations of the electronic configuration, it is comprehensively confirmed that the incorporation of single-atomic Mo sites enables higher oxidation state of the metal and strengthened metal–oxygen hybridization, as well as the formation of oxidized ligand holes above the Fermi level. In a word, the considerable acceleration of water oxidation is achieved via enhancing the reactivity of lattice oxygen and triggering the lattice oxygen activation. This work may provide new insights for designing ideal electrocatalysts via tuning the chemical state and activating the anions ligands., QC 20230228

Selective laser melting (SLM) based processing of Mo-based samples is challenging due to solidification cracking. We here demonstrate that the addition of 2 wt% MoS2 to the Mo feedstock markedly improves crack mitigation of SLM-processed Mo/MoS2/Mo2S3 composite micro-lattice structures (SLM-Mo/ Mo(x)S(x+1)). Crack inhibition is suggested to be a result of Mo2S3 formation, decreased lattice strain (0.04 4%), and a decrease in accumulated residual stresses. The increased values of polarization resistance from 42.3 and 19.2 kU cm2 to 437 and 78.2 kU cm2, respectively verified the hindering effect of the composition on stress corrosion cracking (SCC) and surface oxidation cracking. However, an increased corrosion current density, from 1.22 to 10.2 mA/cm2, and cathodic Tafel constant, from 175 to 260.5 mV, confirmed the decreased polarization resistance and occurrence of different types of corrosion such as SCC and pitting. The strategy to add 2 wt% MoS2 to the Mo feedstock enables the fabrication of hightemperature micro-lattice structure components with improved corrosion resistance properties applicable in e.g., electronic, power semiconductor heat sinks, offshore-, aerospace-, defense-, or particularly novel sodium-ion energy storage applications., QC 20230109

In the present study, we conducted experiments using wheat to elucidate whether the increased accumulation of molybdenum in leaves under nitrogen deficiency is due to the plant’s own metabolic response, and further to estimate the role of molybdenum in the nitrogen deficiency response. Even under different growth conditions such as soil culture, hydroponic culture, and aseptic culture, the nitrogen deficiency always increased the molybdenum accumulation in leaves of wheat. Because molybdenum supply to the soil enhanced the growth of wheat under nitrogen deficiency but did not increase plant nitrogen concentration, the increased molybdenum uptake might be involved in the adaptive mechanisms to nitrogen deficiency by increasing nitrogen use efficiency. Wheat under nitrogen deficiency accumulated more molybdenum in lower leaves. Moreover, the nitrogen concentration of wheat grown under nitrogen deficiency increased in the lower leaves and decreased in the upper leaves with the application of molybdenum. These results suggest that molybdenum might affect nitrogen translocation from older to younger leaves.

Molybdenum disilicide (MoSi2) is one of the most heat and oxidation resistant materials used in high-temperature applications. In this work, the feasibility of forming an oxidation-resistant MoSi2 coating using a low-temperature Sn-Si bath by the hot dipping method was evaluated. It was found that a smooth and dense MoSi2 layer can be successfully synthesized on the surface of a Mo-substrate at 700 °C to 1000 °C. Using this method, MoSi2 can be synthesized more rapidly than using conventional methods and at much low operating temperatures. The diffusion through the product layer controlled the growth of the formed MoSi2 layer, and the growth rate was fastest at 800 °C. This was due to the replacement by the larger tin atoms that led to the expansion of the lattice, allowing the faster diffusion of silicon through the silicide layer towards the unreacted Mo-substrate. Oxidation resistance test at 1150 °C for 2 h confirmed that the MoSi2 layer formed by the present method protects the Mo-substrate from rapid oxidation at elevated temperatures.

Recent work on microbe-host interactions has revealed an important nexus between the environment, microbiome, and host fitness. Marine invertebrates that build carbonate skeletons are of particular interest in this regard because of predicted effects of ocean acidification on calcified organisms, and the potential of microbes to buffer these impacts. Here we investigate the role of sulfate-reducing bacteria, a group well known to affect carbonate chemistry, in Pacific oyster (Magallana gigas) shell formation. We reared oyster larvae to 51 days post fertilization and exposed organisms to control and sodium molybdate conditions, the latter of which is thought to inhibit bacterial sulfate reduction. Contrary to expectations, we found that sodium molybdate did not uniformly inhibit sulfate-reducing bacteria in oysters, and oysters exposed to molybdate grew larger shells over the experimental period. Additionally, we show that microbiome composition, host gene expression, and shell size were distinct between treatments earlier in ontogeny, but became more similar by the end of the experiment. Although additional testing is required to fully elucidate the mechanisms, our work provides preliminary evidence that M. gigas is capable of regulating microbiome dysbiosis caused by environmental perturbations, which is reflected in shell development.

In this study, a novel nitrogen modified carbon quantum dots (NCDs) decorated graphite carbon nitride /molybdenum (Mo) heterojunction photocatalyst (MCN/NCDs) was obtained by in-situ calcination and physical deposition, and applied as peroxymonosulfate (PMS) activators for tetracycline (TC) removal under visible light. It was found that the MCN/NCDs as PMS activation catalyst exhibited outstanding removal efficiency under visible light assistance and nearly 98.4% of TC was degraded within 60 min. The analysis data of photochemistry demonstrated that the introduction of NCDs could significantly improve the visible-light utilization, narrow the band gap and increase the separation of photogenerated electron-hole pairs. The results of radical capture experiment and electron spin resonance test (ESR) suggested that the order of active species contributing to TC degradation in vis/PMS/MCN/NCDs system was O2[rad]– > h+> [rad]OH > 1O2 > SO4[rad]−. Moreover, the MCN/NCDs composite exhibited excellent stability with over 98% activity retention for 5 cycles and superior catalytic efficiency in four real water matrix. Finally, the underlying degradation mechanism and toxicity assessment were proposed in detail. This work provided a new perspective on the design of excellent activity g-C3N4 composite catalysts and elucidated a promising potential strategy for efficient contaminated water treatment via PMS activation process. © 2022 Elsevier B.V.

Phosphate tungsten bronze (WPB) and phosphate molybdenum bronze (MoPB) were synthesized and modified with rhenium. The existing phases were established by X-ray powder diffraction (XRPD), electron paramagnetic spectroscopy (EPR) and Field emission scanning electron microscopy (FESEM). The electroactivity of bronze samples, with and without rhenium for hydrogen evolution reaction (HER) was tested. The influence of carbon black presence in the catalytic ink on the electrochemical activity was investigated. Collected results provide insight into the effects of the constituents of an electrode on its electrochemical activity.

Phosphate tungsten bronze (WPB) and phosphate molybdenum bronze (MoPB) were synthesized and modified with rhenium. The existing phases were established by X-ray powder diffraction (XRPD), electron paramagnetic spectroscopy (EPR) and Field emission scanning electron microscopy (FESEM). The electroactivity of bronze samples, with and without rhenium for hydrogen evolution reaction (HER) was tested. The influence of carbon black presence in the catalytic ink on the electrochemical activity was investigated. Collected results provide insight into the effects of the constituents of an electrode on its electrochemical activity.

Tato práce se zabývá přípravou a charakterizací polosendvičových komplexů molybdenu a wolframu s koordinovaným thioetherovým ligandem. V teoretické části jsou popsány přípravy ligandů obsahujících thioetherovou funkční skupinu, jejich komplexy s přechodnými kovy a vybrané příklady jejich použití v katalýze. Experimentální část je zaměřena na studium protonace allylového ligandu na polosendvičových komplexech molybdenu a wolframu za přítomnosti acetonitrilu nebo monodentátních thioetherových ligandů (dimethylsulfid {SMe2}, tetrahydrothiofen {SC4H8} a 1,4-thioxan {SC4H8O}). Studovány byly jednak polosendvičové komplexy molybdenu, které obsahovali nesubstituovaný cyklopentadienylový ligand, ale také polosendvičové komplexy molybdenu a wolframu, ve kterých byl cyklopentadienylový ligand substituován postranním ramínkem nesoucím thioetherovou funkční skupinu., This work deals with the preparation of half-sandwich complexes of molybdenum and tungsten containing a coordinated thioether ligand. The theoretical section describes the methods of preparation of ligands bearing a thioether functional group, their complexes with transition metals and examples of their use in catalysis. The experimental section is focused on the study of the protonation of the allyl ligand, which is coordinated in the half-sandwich complexes of molybdenum and tungsten, in the presence of acetonitrile or monodentate thioether ligands (dimethylsulfide {SMe2}, tetrahydrothiophene {SC4H8} and 1,4-thioxane {SC4H8O}) The study includes both the half-sandwich complexes of molybdenum with an unsubstituted cyclopentadienyl ligand and the half-sandwich complexes of molybdenum and tungsten with the cyclopentadienyl ligand substituted with a side chain bearing a thioether functional group., Fakulta chemicko-technologická, Diplomant seznámil komisi se svojí diplomovou prací. Dále reagoval na připomínky oponenta. Zodpověděl otázky členů komise: Jaká byla motivace studovat vybrané sloučeniny? Diskutujte ifračervená spetra studovaných sloučenin. Jaká je fotochemická stabilita připravených látek? O kolik je studovaný thioether lépe vázán k centrálnímu atomu kovu?, Dokončená práce s úspěšnou obhajobou

Shells of the fast-growing bivalve Pecten maximus serve as a geochemical archive for the reconstruction of past phytoplankton dynamics. Specifically, high-resolution, temporally accurately aligned molar barium-to-calcium (Ba/Cashell), molybdenum-to-calcium (Mo/Cashell) and lithium-to-calcium ratios (Li/Cashell) of the shell calcite revealed distinct peaks which are closely linked to phytoplankton dynamics. Yet, the development and applicability of these geochemical proxies is still at an early stage and needs further calibration. In this study, we examined the relationship between the timing and magnitude of Ba/Cashell, Mo/Cashell and Li/Cashell peaks of P. maximus and the occurrence of various phytoplankton species (diatoms and dinoflagellates) from a statistical perspective. Studied shell samples (three specimens per calendar year) as well as detailed phytoplankton observation data were derived from the well-studied costal ecosystem of the Bay of Brest (France) over three years (2011, 2012 and 2019). An algorithm-based pseudo-random sampling simulation technique was established that analyzed the complex phytoplankton datasets with respect to the profiles of Ba/Cashell, Mo/Cashell and Li/Cashell to identify potential patterns between phytoplankton and trace element time-series. The simulation results indicate that the timing and magnitude of Ba/Cashell, Mo/Cashell and Li/Cashell peaks agreed best with the occurrence of specific phytoplankton blooms that developed ca. one to two weeks earlier. The data suggest that the formation of transient Ba/Cashell peaks had a plurispecific origin, i.e., potentially linked to blooms of ingestible diatom, dinoflagellate and flagellate species enriched in Ba that occurred 8 to 12 days earlier. Observed peaks in Mo/Cashell profiles demonstrably followed the timing and intensity of blooms of the dominant dinoflagellate genus Gymnodinium spp. after a short time lag of around 8 days, potentially linked to an enhanced enzyme activity o

Masterarbeit Universität Innsbruck 2022

It has been well recognized that the surface reconstruction of electrocatalysts at the initial stage in the form of phase transitions, defect migrations, valence regulations, etc., plays a critical role in generating real, surface active catalytic centers and achieving steady surface reactions. It is also expected that a low activation energy barrier for initiating surface reconstruction is crucial for rapid and stable electrochemical catalysis. Despite this, the surface reconstruction kinetics and their effects on catalytic reactions have been rarely investigated. Herein, using phase modulated polymorphic cobalt-based catalysts with tailorable nitrogen-metal bonds through a cationic molybdenum-substitution strategy, real-time X-ray photoelectron spectroscopy (XPS) structural monitoring of the surface chemical state evolution during the catalytic reaction is performed to track the initial surface reconstruction kinetics during the alkaline oxygen evolution reaction (OER). It is concluded that the molybdenum-modulated cobalt-based nanocatalyst can be tuned with favorable initial surface reconstruction and stabilized active centers to reach optimized OER catalysis, accompanied by a low onset overpotential of only 210 mV and a favorable overpotential at 10 mA cm–2 of 290 mV, outperforming the commercial, noble-metallic RuO2 catalyst. This study thus provides new conceptual insights into rationally regulating the initial surface reconstruction kinetics for high-performance electrocatalysis reactions.

Tungsten is a rare element with a natural abundance thought to be around 1.5 parts per million. It is remarkable for its robust physical properties, making it useful for many industrial applications. Tungsten is the heaviest metal to have a known biological role as it is essential as a cofactor for oxidoreductases in some thermophilic prokaryotes. In animal models, ingested and inhaled tungsten is rapidly absorbed and excreted in the urine. The remaining tungsten in the body is distributed mainly to the spleen, kidney, and bone, with the highest tungsten accumulation in the bone. Tungsten metabolism closely resembles molybdenum in chemical properties. Occupational inhalation exposure to tungsten carbide dust has been linked to cases of pulmonary fibrosis, a hard metal disease, although the contribution of tungsten carbide versus cobalt coexposure is unclear. Small quantities of tungsten are present in food and water and trace quantities, related to industrial emissions, are found in the general atmosphere. Tungsten is also present in human serum, urine, and feces, with elimination approximately balancing intake of the metal in the few nonindustrially exposed subjects studied. Industrial, medical, and military uses of tungsten have been expanding rapidly; therefore, the potential for tungsten spreading into the environment is rapidly increasing.

Recent work on microbe-host interactions has revealed an important nexus between the environment, microbiome, and host fitness. Marine invertebrates that build carbonate skeletons are of particular interest in this regard because of predicted effects of ocean acidification on calcified organisms, and the potential of microbes to buffer these impacts. Here we investigate the role of sulfate-reducing bacteria, a group well known to affect carbonate chemistry, in Pacific oyster (Magallana gigas) shell formation. We reared oyster larvae to 51 days post fertilization and exposed organisms to control and sodium molybdate conditions, the latter of which is thought to inhibit bacterial sulfate reduction. Contrary to expectations, we found that sodium molybdate did not uniformly inhibit sulfate-reducing bacteria in oysters, and oysters exposed to molybdate grew larger shells over the experimental period. Additionally, we show that microbiome composition, host gene expression, and shell size were distinct between treatments earlier in ontogeny, but became more similar by the end of the experiment. Although additional testing is required to fully elucidate the mechanisms, our work provides preliminary evidence that M. gigas is capable of regulating microbiome dysbiosis caused by environmental perturbations, which is reflected in shell development.

The current study is focused on the preparation of Mo-10 vol%La2O3 and Mo-10 vol% La2Zr2O7 composite powders via low- and high-energy ball milling approaches as potential candidates for near-future high-temperature structural applications. The mechanical milling parameters play a critical role on the final powder's microstructure. When using the high-energy milling mode (using 800 rpm, ball-to-powder ratio (BPR) 100: 6), the homogeneous powder agglomerates are formed with refined laminated microstructure and more uniform ceramic phase distribution in both Mo-La2O3 and Mo-La2Zr2O7 systems compared to the powders produced by means of the low-energy milling mode (using 350 rpm, BPR 100: 6), where inhomogeneous powder mixture with less embedding of ceramic phases into Mo agglomerates was obtained. This study also focuses on the evaluation of high-temperature phase and microstructural stability of the produced composite powders treated at the temperature of 1300 degrees C under the different gaseous environments, including ambient, inert and reducing atmospheres. The Mo-10 vol% La2Zr2O7 composite powder exhibited better thermal stability during the high-temperature exposure in all tested atmospheres in comparison with the Mo-La2O3 composite powder, since it revealed less intensive formation of the intermediate phases, such as lanthanum oxymolybdates. Therefore, the Mo-10 vol%La2Zr2O7 composite powder was used further for consolidation by means of spark plasma sintering at 1600 degrees C. The successful production of Mo-La2Zr2O7 composite with homogeneous distribution of ceramic phase, the grain size about of 5 mu m, and hardness of 3.4 GPa was not reported so far.