A solution of the DGLAP equation for gluon at low x

We obtain a solution of the DGLAP equation for the gluon at low x first by expanding the gluon in a Taylor series and then using the method of characteristics. We test its validity by comparing it with that of Glück, Reya and Vogt. The convergence criteria of the approximation used are also discussed. We also calculate εF ₂(x,Q)²/ε In Q ² using its approximate relations with the gluon distribution at low x. The predictions are then compared with the HERA data.     

Rational incorporation of defects within metal–organic frameworks generates highly active electrocatalytic sites

The allure of metal–organic frameworks (MOFs) in heterogeneous electrocatalysis is that catalytically active sites may be designed a priori with an unparalleled degree of control. An emerging strategy to generate coordinatively-unsaturated active sites is through the use of organic linkers that lack a functional group that would usually bind with the metal nodes. To execute this strategy, we synthesize a model MOF, Ni-MOF-74 and incorporate a fraction of 2-hydroxyterephthalic acid in place of 2,5-dihydroxyterephthalic acid. The defective MOF, Ni-MOF-74D, is evaluated vs. the nominally defect-free Ni-MOF-74 with a host of ex situ and in situ spectroscopic and electroanalytical techniques, using the oxidation of hydroxymethylfurtural (HMF) as a model reaction. The data indicates that Ni-MOF-74D features a set of 4-coordinate Ni–O₄ sites that exhibit unique vibrational signatures, redox potentials, binding motifs to HMF, and consequently superior electrocatalytic activity relative to the original Ni-MOF-74 MOF, being able to convert HMF to the desired 2,5-furandicarboxylic acid at 95% yield and 80% faradaic efficiency. Furthermore, having such rationally well-defined catalytic sites coupled with in situ Raman and infrared spectroelectrochemical measurements enabled the deduction of the reaction mechanism in which co-adsorbed *OH functions as a proton acceptor in the alcohol oxidation step and carries implications for catalyst design for heterogeneous electrosynthetic reactions en route to the electrification of the chemical industry.

The allure of metal–organic frameworks (MOFs) in heterogeneous electrocatalysis is that catalytically active sites may be designed a priori with an unparalleled degree of control.     

KF‐Melamine Formaldehyde Resin (KF‐MFR) as a Versatile and Efficient Heterogeneous Reagent for Aldol Condensation of Aldehydes and Ketones under Microwave Irradiation

KF‐Melamine formaldehyde resin (KF‐MFR) was demonstrated to be a highly efficient heterogenious catalyst for cross‐aldol condensation under microwave irradiation. In this synthesis, various aldehydes and ketones were condensed together in the presence of supported KF on melamine‐formaldehyde resin to afford different chalcone derivatives in good to excellent yields. KF‐MFR proved to have unique termal and chemical resistance and can be reused for many consecutive runs without remarkable loss in catalytic activity.     

Overtone spectroscopy of some benzaldehyde derivatives

Overtone spectrum of o, m and p-nitrobenzaldehydes and p-chlorobenzaldehyde has been studied in 2000–12000 cm⁻¹ region. Vibrational frequencies and anharmonicity constants for aryl as well as alkyl CH stretch vibrations have been determined. We have also determined the internuclear distances for the aryl CH bond in the different molecules. The small variation observed in these distances is an indication of the substitution effect. It is observed that in the case of p-disubstituted benzens, the shift in aryl CH bond is proportional to sum of the Hammet σ of the substituents. However in the case of o-disubstituted benzenes it is only 80% of the para-substituted shift.     

Improving separation capability of regenerated cellulose ultrafiltration membrane by surface modification

In this study we introduced dialdehyde groups to a commercial regenerated cellulose (RC) ultrafiltration membrane by periodate oxidation. They were further converted to nitrogen-containing derivatives by Schiff base reaction with diethylenetriamine (DETA). The modified membrane was challenged with aqueous solution containing Pb(II) metal ions. The different variables affecting the rejection of lead ion by membrane including oxidization time, concentration of DETA, initial metal ion concentration and pH of the solution were elucidated. The membranes were characterized by FTIR-ATR, SEM, EDAX and elemental analyses. The process efficiency was enhanced by improving the oxidization time up to a certain period. In our case this was diminished after 9 h due to deterioration in the membrane integrity. The Pb²⁺ removal was facilitated by increasing feed pH and DETA concentration. This was diminished for more concentrated metal ion in the feed. Membrane regeneration was successfully utilized using 0.1 M HNO₃ solution. The removal capability of the regenerated membranes was maintained even after four cycles.     

Interfacing Formate Dehydrogenase with Metal Oxides for the Reversible Electrocatalysis and Solar‐Driven Reduction of Carbon Dioxide

The integration of enzymes with synthetic materials allows efficient electrocatalysis and production of solar fuels. Here, we couple formate dehydrogenase ( FDH ) from Desulfovibrio vulgaris Hildenborough (DvH) to metal oxides for catalytic CO₂ reduction and report an in‐depth study of the resulting enzyme–material interface. Protein film voltammetry (PFV) demonstrates the stable binding of FDH on metal‐oxide electrodes and reveals the reversible and selective reduction of CO₂ to formate. Quartz crystal microbalance (QCM) and attenuated total reflection infrared (ATR‐IR) spectroscopy confirm a high binding affinity for FDH to the TiO₂ surface. Adsorption of FDH on dye‐sensitized TiO₂ allows for visible‐light‐driven CO₂ reduction to formate in the absence of a soluble redox mediator with a turnover frequency (TOF) of 11±1 s^?1. The strong coupling of the enzyme to the semiconductor gives rise to a new benchmark in the selective photoreduction of aqueous CO₂ to formate.     

Meldrum's acid catalyzed reaction of tetracyanoethylene and aldehydes in water: a novel approach to arylidenemalononitrile

Meldrum's acid catalyzed the reaction of tetracyanoethylene with aromatic, heteroaromatic, and conjugated aldehydes led to arylidenemalononitrile in water in good yields at 80 degrees C. The work-up of reactions is very simple and the crude products are sufficiently pure to be used without further purification. The procedure provides an alternative method for the synthesis of arylidenemalononitrile.     

Multiple ionization of argon in coincidence with projectile ions in 60–120 MeV Si q+-Ar collisions

A projectile ion-recoil ion coincidence technique has been employed to study the multiple ionization and the charge transfer processes in collisions of 60–120 MeV Si ^q+ (q = 4−14) ions with neutral argon atoms. The relative contribution of different ionization channels, namely; direct ionization, electron capture and electron loss leading to the production of slow moving multiply charged argon recoil ions have been investigated. The data reported on the present collision system result from a direct measurement in the considered impact energy for the first time. The total ionization cross-sections for the recoil ions are shown to scale as q ^1.7/E _p ^0.5 , where E _p is the energy in MeV of the projectile and q its charge state. The recoil fractions for the cases of total- and direct ionizations are found to decrease with increasing recoil charge state j. The total ionization fractions of the recoils are seen to depend on q and to show the presence of a ‘shell-effect’ of the target. Further, the fractions are found to vary as 1/j ² upto j = 8+. The average recoil charge state 〈j〉 increases slowly with q and with the number of lost or captured electrons from or into the projectile respectively. The projectile charge changing cross-sections σ _qq′ are found to decrease with increasing q for loss ionization and to increase with q for direct-and capture ionization processes respectively. The physics behind various scaling rules that are found to follow our data for different ionization processes is reviewed and discussed.     

Synthesis of highly stable unusual charge-separated pyridinium-, isoquinolinium-, quinolinium-, and N-methylimidazolium-tetronic acid zwitterions

A unique strategy for the synthesis of highly stable unusual charge-separated pyridinium-, isoquinolinium-, quinolinium-, and N-methylimidazolium-tetronic acid zwitterions from the reaction of pyridine, isoquinoline, quinoline, and N-methylimidazole with dialkyl acetylenedicarboxylates and 3-chlorotetronic acid in EtOH at room temperature is described.     

Solar Water Splitting with a Hydrogenase Integrated in Photoelectrochemical Tandem Cells

Hydrogenases (H₂ases) are benchmark electrocatalysts for H₂ production, both in biology and (photo)catalysis in vitro. We report the tailoring of a p‐type Si photocathode for optimal loading and wiring of H₂ase through the introduction of a hierarchical inverse opal (IO) TiO₂ interlayer. This proton‐reducing Si|IO‐TiO₂|H₂ase photocathode is capable of driving overall water splitting in combination with a photoanode. We demonstrate unassisted (bias‐free) water splitting by wiring Si|IO‐TiO₂|H₂ase to a modified BiVO₄ photoanode in a photoelectrochemical (PEC) cell during several hours of irradiation. Connecting the Si|IO‐TiO₂|H₂ase to a photosystem II (PSII) photoanode provides proof of concept for an engineered Z‐scheme that replaces the non‐complementary, natural light absorber photosystem I with a complementary abiotic silicon photocathode.