11 research outputs found
Flash vacuum pyrolysis of benzylidene halides, benzotrihalides and aryl halides over magnesium
This work was supported by B.P.Flash vacuum pyrolysis at 600 °C through glass wool coated with freshly sublimed magnesium is examined as a preparative method for dehalogenative coupling in organic synthesis. Substituted benzylidene chlorides give predominantly the corresponding stilbenes and in some cases these are readily isolated in pure form. With an ortho-halogen substituent, additional cyclisation gives phenanthrenes but the method is not compatible with the presence of several reactive groups. An ortho-methoxy substituent leads to unexpected formation of mono- and dimethyl products. With 1,4-bis(dihalomethyl)benzenes, halogenated polymers are deposited directly from the gas phase via generation of halogenated p-xylylenes. The 1,2- and 1,3-isomers lead respectively to benzocyclobutadiene, isolated as a dimer, and to pyrene. The 1,4-bis(trihalomethyl)benzenes give more highly halogenated polymers directly from the gas phase via halogenated p-xylylenes. While halobenzenes generally give the corresponding benzenes and biphenyls, 1,2-dihalobenzenes additionally produce triphenylene in preparatively useful yield by a process not involving intermediacy of free benzyne.PostprintPeer reviewe
ANTIMYCOBACTERIAL ACTIVITY OF SOME MEDICINAL PLANTS IN NIGER STATE, NIGERIA
Ten Nigerian medicinal plants Abrus precatorius, Annona senegalensis, Anogeissus leiocarpus, Crateva adansonii, Detarium microcarpum, Faba spp, Neocarya macrophylla, Ocimum gratissimum, Securidaca longpenduculata and Terminalia avicennioides used by traditional medicine practitioners for the management of infectious and chronic diseases such as tuberculosis and whooping cough were investigated for in vitro antimycobacterial activity against attenuated strains of Mycobacterium bovis (BCG). Hexane and methanol extracts of the plant materials were obtained by maceration. The antimycobacterial activity was determined by the broth microdilution method. The hexane extracts of Anogeissus leiocarpus and Terminalia avicennioides showed strong inhibitory activity at 312Ôg/ml. Eight of the ten plant extracts showed moderate inhibitory activity in either hexane or methanol extract at 1250Ôg/ml. While the hexane and methanol extracts of Detarium microcarpum and Neocarya macrophylla did not exhibit any significant activity. These observed activities could be associated with secondary metabolites in these plants. This study demonstrates the efficacy of Nigerian medicinal plants as potential agents in the management of the tuberculosis disease
Nanochitosan derived from marine bacteria
Nanochitosans are polysaccharides produced by the alkalescent
deacetylation of chitin and comprise a series of 2-deoxy-2
(acetylamino) glucose linked by Ă-(1-4) glycosidic linkages. These are
naturally formed from the deacetylation of shellfish shells and the
exoskeleton of aquatic arthropods and crustaceans. Reports of
chitosan production from unicellular marine bacteria inhabiting the
sea, and possessing distinct animal- and plant-like characteristics
abound. This capacity to synthesize chitosan from chitin arises from
response to stress under extreme environmental conditions, as a
means of survival. Consequently, the microencapsulation of these
nanocarriers results in new and improved chitosan nanoparticles,
nanochitosan. This nontoxic bioactive material which can serve as an
antibacterial agent, gene delivery vector as well as carrier for protein
and drug release as compared with chitosan, is limited by its
nonspecific molecular weight and higher composition of deacetylated
chitin. This chapter highlights the biology and diversity of
nanochitosan-producing marine bacteria, including the factors
influencing their activities, survival, and distribution. More so, the
applications of marine bacterial nanochitosans in transfection and
gene delivery; wound healing and drug delivery; feed supplement
development and antimicrobial activity are discussed
Next Generation Nanochitosan Applications in Animal Husbandry, Aquaculture and Food Conservation
Studies have identified the properties of enzymes, functionalized
molecules, and compounds in food industry applications as edible
coatings and encapsulations, that assure prolonged food quality and
standards. These molecules present benefits of longer shelf-life by
delayed deterioration and inhibition of the proliferation of spoilage and
mycotoxigenic microorganisms. However, challenges of reduced
nutrient levels, miniaturized size, and low chemical stability remain
concerning. Chitosan polymers naturally formed from the
deacetylation of shellfish shells and exoskeletons of aquatic
arthropods and crustaceans offer improved benefits when
functionalized into nanoparticles as nanochitosans. These
polysaccharides produced by the alkalescent deacetylation of chitin,
comprise a series of 2-deoxy-2 (acetylamino) glucose linked by Ă-(1-
4) glycosidic linkages. This chapter considers the health impacts and
microbiological health hazards associated with animal feeds quality
and the enzyme immobilization potentials of nanochitosans in animalbased
food and feed packages. Thereafter, nanochitosan properties
and benefits are compared against traditional preservatives from
microbes and plants; with highlights on current challenges in the
application of nanochitosan for enzyme immobilization
Chapter 21 - Utilization of nanochitosan in the sterilization of ponds and water treatment for aquaculture
Water pollution constitutes the leading cause of infant mortality,
neonatal deformities, and shrinkage of manâs average life expectancy.
Pollutants come from point and nonpoint sources; and water pollution
arises from the discharge of wastewater containing undesirable
impurities used for domestic, agricultural, and industrial purposes.
More so, high nutrient and wastewater runoffs from fish production
systems contribute to the fouling and eutrophication of recipient water
bodies. Hence, aquaculture which is inextricably linked to the natural
environment is challenged by the dearth of appropriate water quantity
and quality, militating against fish, and fishery production.
Nanochitosans as polysaccharides produced by the alkalescent
deacetylation of chitin, comprise a series of 2-deoxy-2 (acetylamino)
glucose linked by Ă-(1-4) glycosidic linkages. They are naturally
formed from the deacetylation of shellfish shells and exoskeletons of
aquatic arthropods and crustaceans. The unique attributes of chitin
confer a wide range of biotechnological applications on the polymer,
observed in flocculation as a wastewater treatment and purification
route initiated by chitosan. This chapter highlights nanochitosan properties of aquaculture relevance; and elucidates the purification
potentials of nanochitosan, compared to inorganic coagulants and
organic polymeric flocculants. Effects of chitosan on contaminants and
microorganisms, as well as applications in fish pathogens detection,
fish disease diagnosis, and control are discussed
Utilization of nanochitosan in the sterilization of ponds and water treatment for aquaculture
Water pollution constitutes the leading cause of infant mortality,
neonatal deformities, and shrinkage of manâs average life expectancy.
Pollutants come from point and nonpoint sources; and water pollution
arises from the discharge of wastewater containing undesirable
impurities used for domestic, agricultural, and industrial purposes.
More so, high nutrient and wastewater runoffs from fish production
systems contribute to the fouling and eutrophication of recipient water
bodies. Hence, aquaculture which is inextricably linked to the natural
environment is challenged by the dearth of appropriate water quantity
and quality, militating against fish, and fishery production.
Nanochitosans as polysaccharides produced by the alkalescent
deacetylation of chitin, comprise a series of 2-deoxy-2 (acetylamino)
glucose linked by Ă-(1-4) glycosidic linkages. They are naturally
formed from the deacetylation of shellfish shells and exoskeletons of
aquatic arthropods and crustaceans. The unique attributes of chitin
confer a wide range of biotechnological applications on the polymer,
observed in flocculation as a wastewater treatment and purification
route initiated by chitosan. This chapter highlights nanochitosan
properties of aquaculture relevance; and elucidates the purification
potentials of nanochitosan, compared to inorganic coagulants and
organic polymeric flocculants. Effects of chitosan on contaminants and
microorganisms, as well as applications in fish pathogens detection,
fish disease diagnosis, and control are discussed
Nanochitosan derived from marine bacteria
Nanochitosans are polysaccharides produced by the alkalescent deacetylation of chitin and comprise
a series of 2âdeoxyâ2 (acetylamino) glucose linked by Ăâ(1â4) glycosidic linkages. These are naturally
formed from the deacetylation of shellfish shells and the exoskeleton of aquatic arthropods and
crustaceans. Reports of chitosan production from unicellular marine bacteria inhabiting the sea, and
possessing distinct animalâ and plantâlike characteristics abound. This capacity to synthesize chitosan
from chitin arises from response to stress under extreme environmental conditions, as a means of
survival. Consequently, the microencapsulation of these nanocarriers results in new and improved
chitosan nanoparticles, nanochitosan. This nontoxic bioactive material which can serve as an
antibacterial agent, gene delivery vector as well as carrier for protein and drug release as compared
with chitosan, is limited by its nonspecific molecular weight and higher composition of deacetylated
chitin. This chapter highlights the biology and diversity of nanochitosanâproducing marine bacteria,
including the factors influencing their activities, survival, and distribution. More so, the applications
of marine bacterial nanochitosans in transfection and gene delivery; wound healing and drug
delivery; feed supplement development and antimicrobial activity are discussed
Utilization of nanochitosan for enzyme immobilization of aquatic and animal-based food packages
Studies have identified the properties of enzymes, functionalized molecules, and compounds in food industry applications as edible coatings and encapsulations, that assure prolonged food quality and standards. These molecules present benefits of longer shelf-life by delayed deterioration and inhibition of the proliferation of spoilage and mycotoxigenic microorganisms. However, challenges of reduced nutrient levels, miniaturized size, and low chemical stability remain concerning. Chitosan polymers naturally formed from the deacetylation of shellfish shells and exoskeletons of aquatic arthropods and crustaceans offer improved benefits when functionalized into nanoparticles as nanochitosans. These polysaccharides produced by the alkalescent deacetylation of chitin, comprise a series of 2-deoxy-2 (acetylamino) glucose linked by Ă-(1-4) glycosidic linkages. This chapter considers the health impacts and
Estimating the impact of COVID-19 on small and medium scale enterprise: evidence from Nigeria.
This paper examines the effect of COVID-19 related cases and lockdown measures on the issues related to Small and Medium Scale Enterprise in Nigeria. Using an electronic data collection approach, this study analyzes the data using the linear probability model to estimate the effect of the pandemic on the entrepreneurs and model the factors influencing coping strategies using a multivariate probit model. We found that majority of the entrepreneurs have been affected (both severely and slightly) by the COVID-19 pandemics through the partial and total lockdown and movement restrictions. We found that the COVID-19 pandemic's effect differs by sector of the economy (agriculture versus non-agriculture). For instance, partial lockdown measures had an increasing likelihood effect on low sales among the enterprises especially for the non-agricultural sector but there is a contrary result in the context of the food and agriculture sector. In addition, partial lockdown increases the likelihood of switching approaches of business (coping strategies) whereas total lockdown has a negative influence on the coping strategies. One of the policy implications of our study is the need to address social protection approaches (such as palliative measures) which can help to cushion the effect on the pandemic on the Small and Medium Scale Enterprise in Nigeria
Unexpected rearrangement during the gas-phase dehalogenation approach to benzodithiophenes
A range of halogenated methylthiophenes undergo dehalogenative condensation upon FVP over magnesium or calcium to give products including benzodithiophenes; in some cases this involves a novel rearrangement by equilibration of alkenylthienyl radicals via thiophene-fused cyclopropylmethyl intermediates.Publisher PDFPeer reviewe