Chemical Speciation and Bond Lengths of Organic Solutes by Core‐Level Spectroscopy: pH and Solvent Influence on p‐Aminobenzoic Acid

Through X‐ray absorption and emission spectroscopies, the chemical, electronic and structural properties of organic species in solution can be observed. Near‐edge X‐ray absorption fine structure (NEXAFS) and resonant inelastic X‐ray scattering (RIXS) measurements at the nitrogen K‐edge of para‐aminobenzoic acid reveal both pH‐ and solvent‐dependent variations in the ionisation potential (IP), 1s→π* resonances and HOMO–LUMO gap. These changes unequivocally identify the chemical species (neutral, cationic or anionic) present in solution. It is shown how this incisive chemical state sensitivity is further enhanced by the possibility of quantitative bond length determination, based on the analysis of chemical shifts in IPs and σ* shape resonances in the NEXAFS spectra. This provides experimental access to detecting even minor variations in the molecular structure of solutes in solution, thereby providing an avenue to examining computational predictions of solute properties and solute–solvent interactions.     

Self-assembling phenylpropyl ether dendronized helical polyphenylacetylenes

The first example of a self-assembling phenylpropyl ether based dendronized polymer has been reported and its preferred helical handedness has been determined. Dendronized polymer poly(10) and its nondendritic analogue poly(8) are high-cis-content polyphenylacetylenes (PPAs) prepared by using [Rh(nbd)Cl]2/NEt3 (nbd: 2,5-norbornadiene). Both polymers possess a stereocenter in their side chain, which selects a preferred helical handedness. Based on negative exciton chirality observed in the CD spectra of poly(10), we have designated this molecule as a right-handed helical polymer, which persists over a wide temperature range. Poly(10) self-organizes into both Phiioh and Phih lattices in bulk. The Phiioh-to-Phih transition is associated with thermoreversible cis-cisoidal to cis-transoidal isomerization of the helical PPA, accompanied by a dramatic decrease in the column diameter and a decrease in the pi-stacking correlation length along the column. A model for the right-handed helical dendronized PPA has been proposed wherein dendrons from adjacent column strata interdigitate to effectively fill space.     

Associations of Region and Lactation Stage with Odd-Chain Fatty Acid Profile in Triglycerides of Breast Milk in China

Odd-chain fatty acids (OCFAs), with potential value for growing infants, have been reported in breast milk. The association of location and lactation stage with the profile and content of OCFAs in breast milk was studied. We analyzed 1487 breast milk samples collected from 12 areas in China, and 102 infant formulas from different brands were purchased from the local supermarket. The content of sn-2 C15:0 significantly decreased from the colostrum to the mature stage, while that of C17:0 was not significantly increased by the lactation stage (p > 0.05). The content of C15:0 and C17:0 significantly decreased dramatically after the colostrum period, while the content of C13:0 was highest in the mature stage. The level of C15:0 and C17:0 in human milk from Gansu and Xinjiang was significantly higher than that from other areas. Similar trends were observed on the level of sn-2 C15:0 and C17:0, whereas the content of sn-2 C11:0 and C13:0 was significantly higher in breast milk from Shandong. Based on the PDS-LA analysis, the difference among infant formulas, each stage of human milk and human milk from different locations were different. Research is needed to determine if there are health benefits associated with OCFAs.     

Antioxidant,Antimicrobial Activities and Characterization of Polyphenol-Enriched Extract of Egyptian Celery (Apium graveolens L., Apiaceae) Aerial Parts via UPLC/ESI/TOF-MS

Medicinal plant extracts are increasingly considered a major source of innovative medications and healthcare products. This study focused on preparing a polyphenol enriched water extract of Egyptian celery “Apium graveolens L., Apiaceae” aerial parts (TAE) in an endeavor to accentuate its antioxidant capacity as well as its antimicrobial activity. (TAE) of celery was partitioned against different organic solvents to yield dichloromethane (DCM), ethyl acetate (EAC), and butanol (BUOH) fractions. (TAE) and the organic fractions thereof besides the remaining mother liquor (ML) were all screened for their antioxidant capacity using various protocols viz. monitoring the reducing amplitudes for ferric ions (FRAP), and radical scavenging potentials of oxygen (ORAC), 2,2’-azino-bis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH), and metal chelation assays. The examination procedure revealed both (TAE) extract and (DCM) fraction, to pertain the highest antioxidant potentials, where the IC₅₀ of the (TAE) using ABTS and metal chelation assays were ca. 34.52 ± 3.25 and 246.6 ± 5.78 µg/mL, respectively. The (DCM) fraction recorded effective results using the FRAP, ORAC, and DPPH assays ca. 233.47 ± 15.14 and 1076 ± 25.73 μM Trolox equivalents/mg sample and an IC₅₀ 474.4 ± 19.8 µg/mL, respectively. Additionally, both (TAE) and (DCM) fraction exerted antimicrobial activities recording inhibition zones (mm) (13.4 ± 1.5) and (12.0 ± 1.0) against Staphylococcus aureus and (11.0 ± 1.2) and (10.0 ± 1.3) against Escherichia coli, respectively, with no anti-fungal activity. Minimum inhibitory concentration (MIC) of (TAE) and (DCM) fraction were 1250 and 2500 µg/mL, respectively. UPLC/ESI/TOF-MS unveiled the chemical profile of both (TAE) and (DCM) fraction to encompass a myriad of active polyphenolic constituents including phenylpropanoids, coumarins, apigenin, luteolin, and chrysoeriol conjugates.     

A new eudesmane type sesquiterpene from Inula viscosa

Investigation of Inula viscosa of Jordanian origin afforded the new sesquiterpene 1beta-hydroxyilicic acid in addition to the known 2beta-hydroxyilicic acid.     

Combined time- and space-resolved Raman spectrometer for the non-invasive depth profiling of chemical hazards

A time-resolved inverse spatially offset Raman spectrometer was constructed for depth profiling of Raman-active substances under both the lab and the field environments. The system operating principles and performance are discussed along with its advantages relative to traditional continuous wave spatially offset Raman spectrometer. The developed spectrometer uses a combination of space- and time-resolved detection in order to obtain high-quality Raman spectra from substances hidden behind coloured opaque surface layers, such as plastic and garments, with a single measurement. The time-gated spatially offset Raman spectrometer was successfully used to detect concealed explosives and drug precursors under incandescent and fluorescent background light as well as under daylight. The average screening time was 50 s per measurement. The excitation energy requirements were relatively low (20 mW) which makes the probe safe for screening hazardous substances. The unit has been designed with nanosecond laser excitation and gated detection, making it of lower cost and complexity than previous picosecond-based systems, to provide a functional platform for in-line or in-field sensing of chemical substances.     

Industrial development and applications of plant oils and their biobased oleochemicals

In the concepts for new products, performance, product safety, and product economy criteria are equally important. They are taken into account already when the raw materials base for a new industrial product development is defined. Here, renewable resources gain-again after the earlier “green trend” in the 1980s—increasing attention as an alternative raw materials source compared to fossil feedstock. The industrial use of carbohydrates, proteins, and plant oils aligns perfectly with the principles of Responsible Care and is an important part of green chemistry and sustainability in general. Since the 1950s, oleochemistry has grown to a major research and technology area in several institutions and industries. A large variety of products based on fats and oils have been developed since then for different uses, such as specialties for polymer applications, biodiesel, surfactants, emollients for home and personal-care industries, pesticides and biodegradable mineral oil replacements for lubricants. However, at present it seems that the use of renewable resources, especially plant oils, has to compete more and more with the increasing demand for bioenergy, which could cause an unbalanced supply and demand in the future or even a threat for the increasing demand for food in certain areas of the world.     

Photoelectrochemical characteristics of ferric tungstate

Active ferric tungstate was prepared by fusing an equimolar mixture of tungsten oxide and ferric oxide at 1100 °C and annealing at 800 °C for 20 h. Analysis of the electrode material by X-ray diffraction showed that its composition was Fe₂WO₆. When this material was illuminated by visible light in 0.1 M NaOH solution, an anodic photocurrent at a positive potential of 0.5 V (SCE) was obtained. Therefore, this material is considered as an n-type semiconductor. The d.c. conductivity of this material at 25 °C was 4 × 10⁻⁶ Ω⁻¹ cm⁻¹. In the dark, unexpectedly high anodic currents were observed at positive potentials of 0.8 V (SCE) in 0.1 M NaOH. These currents are attributed to the existence of a high density of electron-hole recombination centers within the band-gap of ferric tungstate. When dimethyl viologen (DMV) was used as an electroactive compound in the electrolyte, the anodic photocurrents increased significantly. The oxidation of DMV is thus expected to compete with the electron-hole recombination process. Furthermore, the process of electron-hole recombination was also predicted from the shape of the photocurrent transients under interrupted illumination. These transients exhibited first-order relaxation effects in the region of the onset time of the photocurrents. The band-gap energy of Fe₂WO₆ was found to be about 1.5 eV and its flat-band potential in 0.1 M NaOH was about −0.3 V (SCE). The photoelectrochemical properties of ferric tungstate are explained according to the formalism of the band model of the semiconductor/electrolyte interface. Received: 16 July 1997 / Accepted: 26 September 1997     

Synthesis,Characterization and Application of Cellulose Based Nano-Biocomposite Hydrogels

Nano-hydroxyapatite/cellulose-graft-polyacrylamide biocomposite hydrogels of different molar ratios were prepared to examine their potential application as a carrier for colon targeted drug delivery in vitro. The particle size of the synthesized nano-hydroxyapatite was found to be 122 nm. The swelling behavior of the composite hydrogels was observed in acidic and basic aqueous solution that simulated lower small intestine, colon and stomach fluids. The hydrogel could be applied in drug-delivery systems and acetylsalicylic acid was used as a model compound to test such a possibility. Finally, the synthesized biocomposite hydrogels with the 96.97% maximum encapsulation and 85.67% release efficiency in the basic medium were found to be a suitable candidate to carry and release of colon-targeted drugs.     

Synthesis of palm oil-based fatty methylhydrazide

Fatty methylydrazides (FMHs) have been successfully synthesized from palm oil. Glycerol was produced as a by-product. The synthesis was carried out by reflux palm oil with methylhydrazine in hexane. FMHs have been characterized using elemental analysis, Fourier transform infrared spectroscopy and ¹H nuclear magnetic resonance technique. The results showed that a 6:1 molar ratio of palm oil to methylhydrazine, a round 78 % maximum conversion of palm oil into FMHs and a 10 h reaction time are the optimum reaction conditions.