Impact of the reaction pathway on the final product in on-surface synthesis.

On-surface synthesis provides a very promising strategy for creating stable functional structures on surfaces. In the past, classical reactions known from solution synthesis have been successfully transferred onto a surface. Due to the presence of the surface, on-surface synthesis provides the potential of directing the reaction pathway in a manner that might not be accessible in classical solution synthesis. In this work, we present evidence for an acetylene polymerization from a terminal alkyne monomer deposited onto calcite (10.4). Strikingly, although the dimer forms on the surface as well, we find no indication for diacetylene polymerization. This is in sharp contrast to what is observed when directly depositing the dimers on the surface. The different pathways are linked to the specific arrangement of the dimers on the surface. When forming stripes along the [-4-21] direction, the diacetylene polymerization is prohibited, while when arranged in stripes aligned along the [010] direction, the dimers can undergo diacetylene polymerization. Our work thus constitutes a demonstration for controlling the specific reaction pathway in on-surface synthesis by the presence of the surface.

Characterization of inorganic elements in common consumer plastics using handheld X-ray fluorescence analyzer.

Plastics are increasingly being used in consumer products due to its versatility in many applications. However, these plastics may contain inorganic elements that may be harmful to humans. To determine any potential health risk of plastics, it was important to characterize elemental composition of plastics and assess usage patterns. To investigate plastic usage in a typical Jamaican household and to characterize the inorganic elements in consumer plastics using XRF analyzer. About 200 questionnaires were distributed to households to determine the types and quantity of plastics. A total of 130 plastic samples from 7 categories were collected and measured for inorganic elements using handheld XRF. Household plastics were mainly used for storage and personal hygiene products. On average, 10% of plastics were recycled, while 30% were burned. Inorganic elements present in plastic samples were Cl > Ti > Ba > Fe > Zn > Sb > Cr > Br > Cu > V > Pb > As. Elemental concentrations varied based on the category of plastics. Green plastics had the highest concentrations of each type of elements. This study provided useful information on characterizing the different types of elements present in common household plastics. Results from the survey were used to assess participants' attitude and behaviors towards plastics usage and disposal. It was important to obtain a profile of plastics waste from a typical household. This will allow for more targeted strategies to reduce plastics pollution.

Mercury Exposure Associated with Use of Skin Lightening Products in Jamaica.

BACKGROUND: Skin bleaching is a major health concern among Jamaicans. A common ingredient in skin lightening products is mercury. Mercury is a toxic substance that can cause damage to the gastrointestinal tract, nervous system and kidneys. OBJECTIVE: The objectives of this study were to use different analytical techniques to measure mercury concentrations in popular skin lightening products used in Jamaica and to assess individual levels of mercury exposure based on product usage. METHODS: Sixty skin lightening products were purchased from different vendors across various locations in Jamaica. Each product was initially screened for mercury using a portable handheld energy dispersive X-ray fluorescence (XRF) analyzer. In addition, 25 out of 60 products were further measured using cold vapor atomic absorption spectroscopy (CVAAS). Questionnaires were distributed to users of skin lightening products to determine their usage patterns. RESULTS: Six products had mercury concentrations above the United States Food and Drug Administration (FDA) allowable limit of 1 ppm, of which three products contained alarmingly high concentrations (i.e. > 400 ppm). The majority of products (57 out of 60) had mercury concentrations below 10 ppm. The mercury concentrations in skin lightening products ranged from 0.05 ppm to 17,547 ppm. In our sample, 51% of women and 49% of men used skin products more than once per day. CONCLUSIONS: On average, creams contained more mercury than lotions and soaps. Individuals who use skin lightening products in Jamaica may be at risk for high mercury exposure, as some popular products were found to have mercury concentrations above the allowable limit. COMPETING INTERESTS: The authors declare no competing financial interests.

Bolus consumption of a specifically designed fruit juice rich in anthocyanins and ascorbic acid did not influence markers of antioxidative defense in healthy humans.

Exotic fruits such as açai, camu-camu, and blackberries rich in natural antioxidants (ascorbic acid, anthocyanins) are marketed as "functional" foods supporting a pro-/antioxidant balance. Confirming data from human studies are lacking. Within a randomized controlled crossover trial, 12 healthy nonsmokers ingested 400 mL of a blended juice of these fruits or a sugar solution (control). Blood was drawn before and afterward to determine antioxidants in plasma, markers of antioxidant capacity [trolox equivalent antioxidant capacity, Folin-Ciocalteu reducing capacity, total oxidant scavenging capacity (TOSC)] and oxidative stress [isoprostane, DNA strand breaks in leukocytes in vivo], and their resistance versus H2O2-induced strand breaks. Compared with sugar solution, juice consumption increased plasma ascorbic acid and maintained TOSC and partly Folin-Ciocalteu reducing capacity (both P values < 0.05). Strand breaks in vivo increased after ingestion of both beverages (P < 0.001), probably due to postprandial and/or circadian effects. This anthocyanin-rich fruit juice may stabilize the pro-/antioxidant balance in healthy nonsmokers without affecting markers of oxidative stress.

Chemical characterization and evaluation of antioxidant properties of açaí fruits (Euterpe oleraceae Mart.) during ripening.

Consumption of açaí fruits has been linked to positive health effects due to its phenolic content and nutritive value. The objective of this study was to characterize açaí fruits chemically and to determine the antioxidant capacity at three different maturity stages. With the exception of fat, amounts of macronutrients, minerals and titratable acids decreased during the ripening process. The same trend was observed for most of the phenolic constituents identified by HPLC-ESI-MS/MS. A consistent decline was shown for flavones and hydroxycinnamic acids. The concentration of the anthocyanins increased in the course of ripening. In accordance with the total amount of the identified phenolic compounds, the antioxidant capacity, measured by TEAC and TOSC, also decreased. However, the contribution of the main phenolic compounds to the overall antioxidant capacity evaluated by TOSC was estimated to be low.

Phenolic constituents and antioxidant capacity of four underutilized fruits from the Amazon region.

The Amazon region comprises a plethora of fruit-bearing species of which a large number are still agriculturally unimportant. Because fruit consumption has been attributed to an enhanced physical well-being, interest in the knowledge of the chemical composition of underexplored exotic fruits has increased during recent years. This paper provides a comprehensive identification of the polyphenolic constituents of four underutilized fruits from the Amazon region by HPLC/DAD-ESI-MS(n). Araçá ( Psidium guineense ), jambolão ( Syzygium cumini ), muruci ( Byrsonima crassifolia ), and cutite ( Pouteria macrophylla ) turned out to be primarily good sources of hydrolyzable tannins and/or flavonols. Additionally, different flavanonols and proanthocyanidins were identified in some fruits. The antioxidant capacity was determined by using the total oxidant scavenging capacity (TOSC) assay. Cutite showed the highest antioxidant capacity followed by jambolão, araçá, and muruci.