Miracle-dz/UniFAR-FTUs huggingface dataset:
Recent Developments in Flavin‐based Catalysis

system is able to stabilize three redox states: the oxidized, radical, or reduced one. Furthermore, flavins have the capacity to be excited by light and to react with oxygen to form oxygenated flavin species. Nature has exploited this highly versatile reactivity by the evolution of a wide variety of flavin-containing enzymes that participate in oxidations, reductions, halogenations, and light sensing. Except for their catalytic role in flavoenzymes, natural flavins are also produced to serve other roles: for example, bacteria secrete flavins to serve as electron transfer mediators or antibiotic agents. Most flavoenzymes employ flavin mononucleotide (FMN, Scheme 1 A, R = phosphate) or flavin adenine dinucleotide (FAD, Scheme 1 A, R = ADP, adenosine diphosphate) as cofactor. Dedicated biosynthetic routes lead to formation of these ubiquitous flavin cofactors, starting from riboflavin (vitamin B2) as precursor (Scheme 1 A). Except for these common flavin cofactors, several other flavin analogues have been found to play a role in nature. For example, roseoflavin (Scheme 1 B) is a riboflavin derivative that is produced by certain bacteria. This modified riboflavin has recently received considerable attention as it can be used as an antibiotic. Another example of a natural flavin is the so-called factor 420, or F420 (Scheme 1 C). F420 is an 8-hydroxy-7-demethyl-5-deazariboflavin attached to phospholactate-polyglutamate. This deazaflavin is an obligate 2-electron (hydride) transfer cofactor, analogous to nicotinamide cofactors (“a nicotinamide in flavin’s clothing”). In its dephosphorylated form (F0), this flavin is used as a light-harvesting antenna chromophore. Inspired by the immense functional and chemical diversity of natural flavins and flavoenzymes, flavins and derivatives thereof have been explored as organocatalysts. In the last few years a number of new flavin derivatives and flavin-catalyzed reactions have been reported. In this Minireview recent progress in the area of flavin-based organocatalysis is discussed. The use of novel flavins as catalysts and other non-catalytic applications of modified flavins that have been recently reported are discussed.
NUTRIENT MANAGEMENT IN PECANS

In the desert southwest, commercial pecan growers routinely apply supplemental nitrogen and zinc. Only 40% routinely apply phosphorus, and fewer use boron, iron, and copper. To evaluate nitrogen requirement, rates ranging from 130 to 390 lbs N/a were applied for three seasons in a mature orchard. Nitrogen treatments had little effect on leaf nitrogen concentrations, tree growth, or nut yield. The lower rate of nitrogen application was sufficient to keep leaf nitrogen levels in the sufficient range. Several studies were conducted on soil application of zinc. Results indicate that soil applied ZnSO4 was relatively ineffective, whereas ZnEDTA elevated leaf zinc levels for one to two seasons following application in pot and field studies. Relative to foliar ZnSO4 applications, soil applied Zn-EDTA increased trunk and root zinc levels in young potted trees. Orchard fertigation with Zn-EDTA can effectively elevate foliar zinc concentrations in young trees, although in our study zinc concentrations have not reached sufficiency levels after two growing seasons. Further, the efficacy of fertigated Zn-EDTA has not been demonstrated on mature trees.
A Venturi Disperser as a Dry Powder Generator for Inhalation Studies

AbstractThis paper describes the design and operation of a dry power disperser based on the Venturi principle. The flow in the Venturi tube creates suction near the constricted area to feed powders into the device, and the shear flow downstream of the Venturi tube disperses particles into aerosol form. Powders are fed into the Venturi disperser by a screw feeder. The Venturi tube is simple in design and easy to operate. We have adopted the Venturi/screw feeder as an aerosol generator that can be operated in the flow rate range of between 60 and 200 I/min, as a function of the compressed air pressure and the geometry of the Venturi tube. At low flow rates, this generation system can be adapted for nose-only inhalation exposure to dry powders, and in fact was used to generate quartz and TiO2 for 7-month inhalation studies. Our results indicated that the Venturi tube was useful in providing stable aerosol generation of sticky powders.
Estimating nanoparticle size from diffraction measurements

Nanometre-sized particles are of considerable current interest because of their special size-dependent physical properties. Debye–Scherrer diffraction patterns are often used to characterize samples, as well as to probe the structure of nanoparticles. Unfortunately, the well known `Scherrer formula' is unreliable at estimating particle size, because the assumption of an underlying crystal structure (translational symmetry) is often invalid. A simple approach is presented here which takes the Fourier transform of a Debye–Scherrer diffraction pattern. The method works well on noisy data and when only a narrow range of scattering angles is available.
Interfacial viscoelasticity controls buckling, wrinkling and arrest in emulsion drops undergoing mass transfer

Contrary to the notion that ‘oil and water do not mix’, many oils possess a residual diffusive mobility through water, causing the drop sizes in oil-in-water emulsions to slowly evolve with time. Liquid interfaces are therefore typically stabilized with polymeric or particulate emulsifiers. Upon adsorption, these may induce strong, localized viscoelasticity in the interfacial region. Here, we show that shrinkage of oil drops due to bulk mass transfer may render such adsorption layers mechanically unstable, causing them to buckle, crumple and, finally, to attain a stationary shape and size. We demonstrate using two types of model interfaces that this only occurs if the adsorption layer has a high interfacial shear elasticity. This is typically the case for adsorbed layers that are cross-linked or ‘jammed’. Conversely, interfacial compression elasticity alone is a poor predictor of interface buckling or arrest. These results provide a new perspective on the role of interfacial rheology for compositional ripening in emulsions. Moreover, they directly affect a variety of applications, including the rapid screening of amphiphilic biopolymers such as the Acacia gum or the octenyl succinic anhydride modified starch used here, the interpretation of light scattering data for size measurements of emulsion drops, or the formulation of delivery systems for encapsulation and release of drugs and volatiles.
Effect of polymerization protocol on the degree of conversion of photo- and dual-polymerized self-etch adhesives

Abstract This study investigated the effect of different polymerization protocols on the degree of conversion (DC%) of various photo-polymerized and dual-polymerized self-etch adhesive resins. Five different photo-polymerized (All-Bond Universal, Bisco; G-ænial Bond, GC; Futurabond M+ LC, VOCO; Single Bond Universal LC, 3M ESPE and Peak Universal Bond, Ultradent) and four dual-polymerized self-etch adhesives (Futurabond U, VOCO; Gradia Core SE, GC; Futurabond M+ DC, VOCO and Single Bond Universal DC, 3 M ESPE) were tested. All adhesives were applied on potassium bromide pellets (KBr) following the manufacturer’s instructions. The KBr pellets were divided into 10 experimental groups for the photo-polymerized adhesives and 12 experimental groups for the dual-polymerized adhesives according to the two levels of the study, Level 1: polymerization protocol and Level 2: adhesive system. For the photo-polymerized adhesives, the adhesives were polymerized either at 1 or 10 mm from the KBr pellets. For the photo-polymerized adhesives, the adhesives were photo-polymerized either at 1 or 10 mm distance or polymerized chemically. The DC% of the unpolymerized and polymerized adhesives was assessed using Fourier transform infrared spectroscopy. Data were analyzed using two-way ANOVA to evaluate the effect of polymerization protocol, adhesive system, and their interaction on the DC% of the self-etch adhesives. For the photo-polymerized and dual-polymerized adhesives, one-way ANOVA and Tukey HSD post hoc test was used to evaluate the effect of adhesive system within each polymerization protocol and the effect of polymerization protocol within each adhesive for the dual-polymerized adhesives (p = 0.05). Student t-test was used to compare the effect of polymerization distances within each photo-polymerized adhesive. For both photo- and dual-polymerized adhesives, the polymerization protocol and adhesive system had a significant effect on the DC (p = 0.000). The interaction between the two factors (polymerization protocol and adhesive system) revealed also a significant effect on the DC% of the different adhesives (p = 0.000). Polymerization distance of 1 mm showed significantly higher DC% compared to 10 mm distance. When the dual-polymerized adhesives were left to set chemically, they showed the lowest DC% among all polymerization protocols. DC varied depending on the chemical composition of the self-etch adhesives. The tip of the polymerization device should be positioned as close as possible to the surface to achieve higher DC% of the tested adhesives. Photo-polymerization of the dual-polymerized self-etch adhesives is a mandatory step to improve their DC.
Tribological property study of novel water-soluble triazine derivative

2,4-Di-(diethanolamine)-6-(diethanolaminedithiocarbamate)-1,3,5-triazine, a novel water-soluble triazine derivative, was synthesized. As additive in pure water and water-glycol, its tribological behaviors were evaluated by a four-ball tester. The results showed that this new triazine derivative exhibited excellent extreme pressure, antiwear, and friction-reducing properties. The compound can be used as a new multifunctional lubricant additive in pure water and water-glycol. The wear scar diameter and friction coefficient increased along with the rotation speed under the condition of using water-glycol as base liquid. The morphology of worn surface and the element composition of the surface were analyzed by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. The analysis results showed that the additive generated a boundary lubricating and a protecting film, which contained FeOx, FeSO4, FeS2, and organic N-containing compounds. This consequence may contribute to the improvement of tribological properties of water-base lubricant.
Synthesis of PMMA-b-PS Block Copolymer by Emulsion ATRP and its Self-Assembly Property

The well-defined block copolymer PMMA-b-PS was prepared by two-step ATRP in emulsion system. GPC results indicate that Mn increased linearly with conversion and polydispersity remained relatively narrow. It presents the characteristics of living polymerization in emulsion system. FT-IR demonstrated that block copolymer PMMA-b-PS could be successfully synthesized by ATRP with macroinitiator PMMA-Cl in emulsion system. The morphological characteristic of the self-assembly depends on the block copolymer concentration and transforms between spheres and rodlike micelles. The property indicates a perfect potential application in drug delivery materials.
MOF-5/n-Bu4NBr: an efficient catalyst system for the synthesis of cyclic carbonates from epoxides and CO2 under mild conditions

The development of efficient heterogeneous catalysts for the cycloaddition of CO2 with epoxides to produce five-membered cyclic carbonates under mild reaction conditions is of great importance. In this work, the coupling reaction of CO2 with propylene oxide (PO) to produce propylene carbonate (PC) catalyzed by MOF-5 (metal-organic frameworks) in the presence of quaternary ammonium salts (Me4NCl, Me4NBr, Et4NBr, n-Pr4NBr, n-Bu4NBr) was studied in different conditions. It was discovered that MOF-5 and quaternary ammonium salts had excellent synergetic effect in promoting the reaction, and the MOF-5/n-Bu4NBr catalytic system was the most efficient among them. The optimal temperature for the reaction was around 50 °C. The reaction could be completed in 6 h at low CO2 pressure with very high selectivity. A decrease of the yield of PC was not noticeable after MOF-5 was reused three times, indicating that the MOF-5 was stable. The MOF-5/n-Bu4NBr catalytic system was also very active and selective for the cycloaddition of CO2 with other epoxides, such as glycidyl phenyl ether, epichlorohydrin and styrene oxide. The mechanism for the coupling reaction is also discussed.
The interpretation of intensity distributions from disordered binary alloys

X-ray diffuse scattering from disordered alloys is the primary direct source of information concerning the Warren parameters which describe the existing state of order. However, the short range order diffuse intensity is obscured by other contributions to the diffraction pattern resulting from static atomic displacements from the average lattice, and from effects related to thermal motion. Described here is a method to separate the diffraction pattern into its various components so that each may be interpreted independently. No assumptions are made about the nature of the atomic displacements δ, except that they are sufficiently small, and that the diffraction vector k/2π is sufficiently small, that terms beyond the term quadratic in k . δ may be neglected in the series expansion of exp [ik . δ].
Formation of silk–gold nanocomposite fabric using grapefruit aqueous extract

Gold nanostructures were synthesized by reduction of gold ions using aqueous extract of grapefruit pulp (Citrus paradisi). This eco-friendly bioreduction method allows the formation in solution and support of gold nanostructures on silk fibers. Bioreduction techniques involve biomolecules of grapefruit extract for reducing a gold precursor to obtain different kinds of nanostructures. Carbohydrates and organic acids, present in C. paradise, are believed to be responsible for the formation of nanoparticles. Analysis of gold–silk nanocomposites by electron microscopy shows gold nanostructures with quasi-spherical, hexagonal, and triangle shapes. The evolution of functional groups in the silk fibers before and after the bioreduction process was followed by infrared spectroscopy. Diffuse reflectance spectroscopy (DRS) and laser scanning confocal microscopy (LSCM) were used to probe surface plasmon resonance and fluorescent behavior in the silk–gold composite. This simple and novel methodology for obtaining these types of nanocomposite may have important applications in the development of functional fibers.
Crop thinning (hand versus mechanical), grape maturity and anthocyanin concentration: outcomes from irrigated Cabernet Sauvignon ("Vitis vinifera L.") in a warm climate

Crop thinning subsequent to fruit set can help regulate yield and improve fruit composition at harvest. Accordingly, an experiment was established in two vineyards (Site 1 Riverland District of South Australia; Site 2 Sunraysia District of Victoria) to investigate effects of crop removal after fruit set (when berries were pea size) using a machine harvester. Specific zones of the canopy were targeted for thinning to remove a predetermined percentage of the fruit and avoid over-thinning. Cropping responses to mechanical thinning were compared with control (un-thinned) vines, and with hand thinned vines (where fruit was removed from a similar portion of the canopy as for mechanical thinning). In a fourth treatment, bunches damaged by mechanical thinning were removed by hand. Inclusion of hand thinning treatments enabled us to distinguish between the potential benefits of reduced yield and the potential damage caused by the mechanical harvester to foliage and/or remaining fruit. Both the mechanical and the hand thinning treatments reduced bunch number as well as yield by a similar amount (approximately 24% on Site 1 and approximately 45% on Site 2) and advanced fruit maturity (soluble solids accumulation at harvest), relative to un-thinned controls, by approximately 1.6 % and 1.7% respectively. Soluble solids accumulated at a similar rate for all treatments at sites, despite differences in yield, implying that the impact of thinning treatments originated prior to veraison. Berry weight was increased by hand thinning at Site1, and by all thinning treatments at Site 2. Anthocyanin concentration (berry fresh weight basis) was higher in fruit from the mechanically thinned vines compared to controls (un-thinned). Mechanical thinning successfully reduced crop level to the target yield, and improved fruit quality. Mechanical thinning, via modified use of a machine harvester, thus offers some potential to regulate yield over large and minimally pruned vineyards, in a timely and cost-effective fashion.
East versus West in the US: Chemical Characteristics of PM2.5 during the Winter of 1999

The chemical composition of PM2.5 was investigated at four sites (Rubidoux, CA, Phoenix, AZ, Philadelphia, PA, and Research Triangle Park, NC) in January and February of 1999. Three samplers were used to determine both the overall mass and the chemical composition of the aerosol. Teflon filters were weighed for total mass. Ions were analyzed using ion chromatography. Elements were determined using X-ray fluorescence. Organic and elemental carbon were measured using a thermo-optical method. At all of the sites, reconstructed mass was observed to be greater than or equal to the measured mass. Good ionic balance was found for ammonium, nitrate, and sulfate at each of the sites. Overall, the chemical composition of the aerosol for each site was in good agreement with the expected composition based upon previous studies, with the exception of relatively high nitrate contribution to the total mass at Philadelphia. Good agreement was found between the predicted amount of sulfate by XRF analysis of sulfur and the sulfate measured by ion chromatography. As expected, sulfate was a more important contributor to the total mass at the East Coast sites. Nitrate contributed more to the total mass at the West Coast sites and was an important factor in the highest observed mass concentration at Rubidoux. Teflon filters appear to lose nitrate to a greater extent than heat-treated quartz fiber filters. Organic carbon was also found to be the largest part of the aerosol mass on minimum days for all sites and a significant portion of the mass on other days with 25-50% of the total mass at all of the sites. At three of the sites, organic carbon (OC) collected on denuded filters was less than that found on nondenuded samples, indicating an absorptive artifact on the quartz fiber filters. It was also found that the crustal component to PM2.5 was highest at Phoenix. PM2.5 was also found to contribute significantly to the PM10 particle mass at all the sites.
Effects of symbiosis with Rhizobium fredii on transport of fixed nitrogen in the xylem of soybean plants

Abstract An experiment was conducted to identify the main nitrogenous compound transported in the xylem sap of soybean plants nodulated with Rhizobium fredii. Soybean (Glycine max L. Merr.) cultivars, wild type Bragg (nod+, fix+) and its nitrate tolerant, hypernodulating mutant ntsll16 (nod++, fix+) were used for this experiment. These soybean plants were inoculated with a slowgrowing rhizobium, Bradyrhizobium japonicum USDAllO or fast-growing rhizobia consisting of a mixture of R. fredii USDA191, USDA193, and USDA-194 and grown in a phytotron under natural light and controlled temperature conditions. Xylem sap was collected from Bragg and ntsll16 plants at the flowering and pod elongation stages. Acetylene reduction activity per plant or per nodule weight was not different between soybean lines and inoculums. The composition of the nitrogenous compounds in the xylem sap was compared between the symbionts, with B. japonicum and R. fredii. At the flowering stage, ureide-N and amide-N accounted for 53 to 70% and 20 to 27% respectively of the total N in the sap collected from the plants inoculated either with B. japonicum or R. fredii. At the pod elongation stage, ureide-N and amide-N accounted for 74 to 85%, and 7 to 19% of total sap N. With the growth of the soybean plants, the ratio of ureide-N in the xylem sap increased. These results suggest that in the case of wild soybean and the hypernodulating mutant line nodulated by R. fredii, ureide is transported as the main nitrogenous compound of fixed nitrogen in the xylem sap in the same way as in plants nodulated with B. japonicum.
Geometric transitions on non‐Kähler manifolds

This article is based on the publications [1–3] and the author's PhD‐thesis. We study geometric transitions on the supergravity level using the basic idea of [1], where a pair of non‐Kähler backgrounds was constructed, which are related by a geometric transition. Here we embed this idea into an orientifold setup as suggested in [3]. The non‐Kähler backgrounds we obtain in type IIA are non‐trivially fibered due to their construction from IIB via T‐duality with Neveu–Schwarz flux. We demonstrate that these non‐Kähler manifolds are not half‐flat and show that a symplectic structure exists on them at least locally. We also review the construction of new non‐Kähler backgrounds in type I and heterotic theory as proposed in [2]. They are found by a series of T‐ and S‐duality and can be argued to be related by geometric transitions as well. A local toy model is provided that fulfills the flux equations of motion in IIB and the torsional relation in heterotic theory, and that is consistent with the U‐duality relating both theories. For the heterotic theory we also propose a global solution that fulfills the torsional relation because it is similar to the Maldacena–Nunez background.
Comparative study of the antifungal activity of essential oils from aromatic plants growing wild in the central region of Argentina

The essential oils of Salvia gilliessi Benth. , Satureja parvifolia (Phil.) Epl. , Lippia polystachya Gris. and Lippia junelliana (Mold.) Tronc. which were produced from plants collected in the central region of Argentina, were analysed by GC. The oil of S. gilliessi was found to be rich in hydrocarbons (>68%). The most abundant compounds in S. parvifolia oil were alcohols and oxides (>77%), while the oils of the L. polystachya and L. junelliana contained ketones (>56%) as major components. The effect of S. gilliessi, S. parvifolia, L. polystachya and L. junelliana oils on spore germination and mycelial growth of three phytopathogenic fungi Alternaria solani (Ell. et Mart.), Sclerotium cepivorum Berk. and Colletotrichum coccodes (Wallr.) Hughes were studied. The essential oils exhibited mycelial inhibition at . a concentration of 1%. The three fungi were identical in their sensitivity towards the four oils.
Polyzwitterion-to-polyampholyte transition using pH-responsive cycloterpolymers of diallyldimethylammonium chloride, (N,N-diallylammonio)methanecarboxylate and sulfur dioxide

The cycloterpolymerizations of varying proportions of diallyldimethylammonium chloride (I) and N,N-Diallyl-N-carboethoxymethylammonium chloride (II) in the presence of sulfur dioxide afforded a series of cationic (+) polyelectrolytes (CPEs) (III) in excellent yields. CPEs, upon acidic hydrolysis of the ester functionalities of the repeating units of II, resulted in the formation of cationic/zwitterionic (+/±) polymers (IV). pH-responsive zwitterionic units of ammonioethanoate (NH+CH2CO) (having unquenched valency of nitrogen) in IV was converted to its anionic counterparts (NCH2CO) by treating with equivalent amount of NaOH to give cationic/anionic i.e., ampholytic (+/−) polymers (V) with a charge symmetry or asymmetry arising out of either excess of cationic or anionic centers. The transformations of III to IV to V have thus provided an opportunity to study the effects of the polyelectrolyte-to-polyzwitterion-to-polyampholyte transitions on the solution properties of these polymers. Basicity constants of the carboxylate group (NH+CH2CO) in IV as well as the amine group (NCH2CO) in V were found to be “apparent” and as such follow the modified Henderson–Hasselbalch equation. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012