Covalent organic frameworks(COFs), as an emerging class of porous crystalline materials constructed by covalent links between the building monomers, have gained tremendous attention. Over the past 15 years, COFs have ...Covalent organic frameworks(COFs), as an emerging class of porous crystalline materials constructed by covalent links between the building monomers, have gained tremendous attention. Over the past 15 years, COFs have made rapid progress and substantial development in the chemistry and materials fields. However, the synthesis of COFs has been dominated by solvothermal methods for a long time and it usually involves high temperature, high pressure and toxic organic solvents, which created many challenges for environmental considerations. Recently,the exploration of new approaches for facile fabrication of COFs has aroused extensive interest. Hence, in this review, we comprehensively describe the synthetic strategies of COFs from the aspects of nonconventional heating methods and reaction media. In addition, the advantages,limitations and properties of the preparation methods are compared. Finally, we outline the main challenges and development prospects of the synthesis of COFs in the future and propose some possible solutions.展开更多
Objetive: To explore the potential insecticidal, ovipositor deterrent and antifeedant effects of ethyl acetate extract of the seeds of Senna tora(Syn. Cassia tora) against cowpea weevil(Callosobruchus maculatus).Metho...Objetive: To explore the potential insecticidal, ovipositor deterrent and antifeedant effects of ethyl acetate extract of the seeds of Senna tora(Syn. Cassia tora) against cowpea weevil(Callosobruchus maculatus).Method: The activities were evaluated using standard protocols.In these bioassays, the cowpea seeds were used directly as an insect feed. The activity of the extract and isolated compounds were tested at concentrations of 100, 200 and 300 μg/mL and compared to neem oil and cinnamaldehyde(as standard positive controls). Phytochemical analysis of the ethyl acetate extract was done through a number of chromatographic techniques and the structures of the isolated compounds were established through comprehensive spectroscopic analysis including 2 D-NMR and ESI-MS studies.Results: Fractionation of the active ethyl acetate extract resulted in the isolation of one known anthraquinone,aurantio-obtusin(1) and a novel compound that was named as cassiatorin(2). Compounds1 and 2 showed comparable insect antifeedant properties with the positive controls while their insecticidal and ovipositor deterrent effects were far superior to the standard controls.Conclusions: It is thus concluded that Senna tora extracts and the isolated compounds(1 and2) may be employed in the postharvest management of stored cowpea seeds and as other crop protectants.展开更多
In this paper, a novel series of bis [(aminoethyl)]-amine cationic lipid derivatives have been synthesized and identified to purity by NMR and Elemental analysis. B16-F0 cells were transfected with cationic lipid/pEGF...In this paper, a novel series of bis [(aminoethyl)]-amine cationic lipid derivatives have been synthesized and identified to purity by NMR and Elemental analysis. B16-F0 cells were transfected with cationic lipid/pEGFP-N1 and cationic lipid/ß-gal lipoplexes complexed at +/- charge ratios of 1:1, 2:1, and 4:1. Dimyristoyl derivative showed highest activity at charge ratio 2:1 and both dimyristoyl and dioleoyl derivatives showed similar ß-gal activity at charge ratios 4:1. In 40 mM tris buffer pH 7.2 the dioleoyl derivative was able to fully complex with and retard pDNA at charge ratios above 2:1. None of the other lipid derivatives, dilauroyl, dimyristoyl, dipalmitoyl and distearoyl were able to fully neutralize the plasmid DNA at charge ratios similar to those used in the transfection experiment. The gel-to-liquid phase transition temperatures for dimyristoyl, dipalmitoyl and distearoyl were determined by a fluorescence anisotropy method to be 27.5°C, 32.5°C and 39°C, respectively. A gel-to-liquid crystalline phase transition temperature below 37°C, appears to be the crucial property that cationic lipids have to possess in order to mediate high levels of in vitro transfection activity in the absence of other helper lipids.展开更多
This study investigated a natural indicator for acid-base titration which is extracted from guinea corn leaves popularly called “waakye leaves” in Ghana. Four types of acid-base titration were studied: strong acid v...This study investigated a natural indicator for acid-base titration which is extracted from guinea corn leaves popularly called “waakye leaves” in Ghana. Four types of acid-base titration were studied: strong acid versus (v/s) strong base, strong acid versus weak base, weak acid versus strong base, and weak acid versus weak base. The indicator color change, pH range and the average titre values were determined for each type of acid-base titration. These values were comparable to those obtained from three standard indicators: methyl orange, methyl red and phenolphthalein. Total flavonoids (TF) and condensed tannin (CT) from the crude leaves extract were determined which might be the major reasons for the activity of the extract as an indicator for simple acid-base titration. The authors suggest that the natural indicator is cheap, available, simple to extract, user and environmentally friendly and could be an excellent replacement for standard indicators.展开更多
Novel type of polyethylene imine having methoxy (–OCH3) substituent azobenzene side chain group through eight methylene spacer group (PEI8M) was successfully synthesized and characterized by the polymer by 1H NMR, di...Novel type of polyethylene imine having methoxy (–OCH3) substituent azobenzene side chain group through eight methylene spacer group (PEI8M) was successfully synthesized and characterized by the polymer by 1H NMR, differential scanning calorimetry, polarized optical microscopic and X-ray diffraction analysis. Synthesized polymer possessed liquid crystalline (LC) properties. Spin coated PEI8M film showed out-of-plane molecular orientation on annealing and non-polarized visible light irradiation. PEI8M in solid film exhibited photoresponsive properties upon irradiation of UV and visible light. PEI8M film also exhibited reversible molecular orientation from random state to out-of-plane and from out-of-plane to random state on annealing, non-polarized UV and visible light irradiation.展开更多
The effect of equal-channel angular pressing(ECAP) on the pitting corrosion resistance of anodized Al-Cu alloy was investigated by electrochemical techniques in a solution containing 0.2 mol/L AlCl3 and also by surfac...The effect of equal-channel angular pressing(ECAP) on the pitting corrosion resistance of anodized Al-Cu alloy was investigated by electrochemical techniques in a solution containing 0.2 mol/L AlCl3 and also by surface analysis.Anodizing was conducted for 20 min at 200 and 400 A/m2 in a solution containing 1.53 mol/L H2SO4 and 0.018 5 mol/L Al2(SO4)3·16H2O at 20 ℃.Anodized Al-Cu alloy was immediately dipped in boiling water for 20 min to seal the micro pores present in anodic oxide films.The time required before initiating pitting corrosion of anodized Al-Cu alloy is longer with ECAP than without,indicating that ECAP process improves the pitting corrosion resistance of anodized Al-Cu alloy.Second phase precipitates such as Si,Al-Cu-Mg and Al-Cu-Si-Fe-Mn intermetallic compounds are present in Al-Cu alloy and the size of these precipitates is greatly decreased by application of ECAP.Al-Cu-Mg intermetallic compounds are dissolved during anodization,whereas the precipitates composed of Si and Al-Cu-Si-Fe-Mn remain in anodic oxide films due to their more noble corrosion potential than Al.FE-SEM and EPMA observation reveal that the pitting corrosion of anodized Al-Cu alloy occurs preferentially around Al-Cu-Si-Fe-Mn intermetallic compounds,since the anodic oxide films are absent at the boundary between the normal oxide films and these impurity precipitates.The improvement of pitting corrosion resistance of anodized Al-Cu alloy processed by ECAP appears to be attributed to a decrease in the size of precipitates,which act as origins of pitting corrosion.展开更多
In this study, we validated the effect of Moringa oleifera leaves as food supplement on poultry. Proximate neutron activation analysis was used in determining the level of some of the vital nutritional minerals and po...In this study, we validated the effect of Moringa oleifera leaves as food supplement on poultry. Proximate neutron activation analysis was used in determining the level of some of the vital nutritional minerals and potential toxic elements in the serum of the birds during the experimental process, including Magnesium, Copper, Vanadium, Chlorine, Aluminum, Manganese, Calcium, Mercury, Cadmium, Arsenic, Sodium and Potassium. Incorporation of Moringa oleifera leaves in maize meal fed to poultry showed profound, statistically significant effect on their weight (p > 0.05) as well as intensity in coloration of the beaks and legs, combs and wattles, in contrast to a control (maize-meal only) feeding of broilers (p > 0.05). Moreover, a significant level of the biochemical minerals of serum Calcium (1.17 - 1.20 mmol·L-1), Sodium (141.6 - 152.6 mmol·L-1), Potassium (4.1 - 5.7 mmol·L-1), Chloride (95 - 110 mmol·L-1), Albumen (30 - 55 mmol·L-1) and Triglyceride (0.3 - 1.7 mmol·L-1) were observed in broilersfed with the formulated Moringa oleifera leaves and maize meal as compared to the maize meal only (control). Addition of Maringa oleifera leaves to poultry feed will lead to high output performance in poultry production.展开更多
The effect of the application of oil from baobab seeds on the antioxidant capacity and stability of ascorbic acid in the fruit pulp at varying temperature were evaluated. Ascorbic acid analysis of the fruit pulp revea...The effect of the application of oil from baobab seeds on the antioxidant capacity and stability of ascorbic acid in the fruit pulp at varying temperature were evaluated. Ascorbic acid analysis of the fruit pulp revealed that the concentration in the raw extract of the pulp sullied rapidly matched with the extract treated with the seed oil. Compared with the raw extracts the formulated fruit pulp presented the highest concentration of the total ascorbic acid when both samples were subjected to varying temperatures at extended time periods. The results clearly indicated the antioxidant enrichment property of the baobab seed oil. This study demonstrates the potential of oil derived from baobab seed as having antioxidant enrichment capacity and might be a potential ingredient in pharmaceutical cosmetics formulations and food preparations.展开更多
Background: To contribute to a fuller appreciation of Ghana’s HIV epidemic, this paper presents various profiles of the Ghanaian HIV-affected household. To comprehensively tackle the HIV epidemic in Ghana, the profil...Background: To contribute to a fuller appreciation of Ghana’s HIV epidemic, this paper presents various profiles of the Ghanaian HIV-affected household. To comprehensively tackle the HIV epidemic in Ghana, the profiles would provide stakeholders with ready information for policy formulation. Methods: We used data from a nationally representative survey that measured livelihood activities, household asset wealth, household composition, health, and nutrition variables of 1745 HIV-affected households. From these emerged various profiles. Results: About 50% of the households are headed by females. Households headed by men have an average size of three members, compared to two for female-headed households. There are far more AIDS widows than widowers. The annual death rate among the surveyed households was about 1000 per 100,000-households. Relatively more deaths occurred in male-headed households. Two-thirds of the households were asset poor. Various coping strategies were instituted by the households in reaction to threat of food insecurity. The national prevalence of chronic energy deficiency is 16%. Conclusions: Our data show that age of household head, hosting of a chronically ill member, and average size of household differed by sex of household head. The annual death rate of 1000 per 100,000 households is very high.展开更多
Polyphenolic compounds with relatively high antioxidant activity obtained from subcritical water extraction of apple pomace were assessed for encapsulation by spray drying technique, making use of polymeric substances...Polyphenolic compounds with relatively high antioxidant activity obtained from subcritical water extraction of apple pomace were assessed for encapsulation by spray drying technique, making use of polymeric substances co-extracted with the polyphenolic compounds. Comparative assessments were carried out of the directly encapsulated subcritical water extract (SWE) products with particles formed when encapsulated with the addition of hydroxyl propyl-β-Cyclodextrin (SWE + HPβ-CD). The powders were characterized for their physico-chemical properties such as, moisture content, density, particle size, hygroscopicity to assess their suitability within cosmetic formulations. The SWE and SWE + HPβ-CD encapsulated products resulted in different physical properties. Although the particle size was less than 4 μm for both products, the direct encapsulation (SWE) was highly hygroscopic and this property was significantly reduced with addition of HPβ-Cyclodextrin (SWE + HPβ-CD). Scanning electron microscopy (SEM) and Fourier Transform Infrared (FT-IR) spectroscopic were em-ployed to analyse the micronised powders to support evidence of encapsulation. Both techniques revealed the interaction between compounds in extract and the carrier HPβ-Cyclodextrin suggesting successful encapsulation. The effect of storage conditions on retention of antioxidant activity of the subcritical water extract was evaluated within 35 days for extracts with and without the carrier HPβ-Cyclodextrin. Hydroxyl propyl-β-Cyclodextrin offered protection against degradation of antioxidant compounds thereby potentially extending the shelf-life and making the encapsulated powder suitable for incorporation in cosmetic and pharmaceutical applications.展开更多
A highly selective ligand exchange type adsorbent was developed for the removal of trace arsenic(V) (As(V)) and phosphate from water. This adsorbent was prepared by loading zirconium(IV) on monophosphonic acid resin. ...A highly selective ligand exchange type adsorbent was developed for the removal of trace arsenic(V) (As(V)) and phosphate from water. This adsorbent was prepared by loading zirconium(IV) on monophosphonic acid resin. This adsorbent was able to remove toxi canions efficiently at wide pH ranges. However, low pH was preferable for maximum breakthrough capacity in an adsorption operation.The effect of a large amount of competing anions such as chloride, bicarbonate, and sulfate on the adsorption systems of As(V) andphosphate anions was investigated. The experimental findings revealed that the As(V) and phosphate uptakes were not affiected by thesecompeting anions despite the enhancement of the breakthrough points and total adsorption. Phosphate anion was slightly preferablethan As(V) in their competitive adsorption by the adsorbent. The adsorbed As(V) and phosphate on the Zr(IV)-loaded resin werequantitatively eluted with 0.1 mol/L sodium hydroxide solution, and the adsorbent was regenerated by 0.5 mol/L sulfuric acid. Duringseveral cycles of adsorption-elution-regeneration operations, no Zr(IV) was detected in the column efluents. Therefore, the Zr(IV)-loaded monophosphonic acid resin is an effective ligand exchange adsorbent for removing trace concentrations of As(V) and phosphatefrom water.展开更多
Eggshells are among the emerging hazardous waste from the food processing industry. This work sought to valorize waste guinea fowl eggshells. Guinea fowl eggshells (GFEs) were evaluated in the production of CaO for ch...Eggshells are among the emerging hazardous waste from the food processing industry. This work sought to valorize waste guinea fowl eggshells. Guinea fowl eggshells (GFEs) were evaluated in the production of CaO for chemical and industrial application. The functionality, thermal stability, elemental composition, phase distribution and surface morphology properties of uncalcined GFEs and GFEs calcined at 700°C, 800°C, 900°C, 1000°C and 1100°C were systematically studied by FTIR, TGA, XRF, XRD and SEM-EDX respectively. The elemental analysis revealed Ca as the main element in the GFEs. The uncalcined GFEs showed intense peaks that corresponded to calcite (CaCO3) phases. These transformed into Ca(OH)2 as the temperature of calcination increased and finally to CaO in the FTIR analysis. In the XRD diffractograms, the main peaks at 2θ values were 29.466° for the uncalcined GFESs and at 37.377° for the sample treated at 1100°C. The phases were confirmed as CaO when compared with JCPDS files. Using the Scherer equation, the CaO crystallite size for the sample calcined at 1100°C was found to be 50.68 nm along the (2 0 0) orientation. All the samples showed multi-step decomposition patterns in the thermogravimetric analyses (TGA), with weight loss of up to 47% for the uncalcined GFEs sample, which was mainly due to the transformation of the calcite (CaCO3) phase to CaO by removal of bound water, organic components, and CO2. Samples calcined at 1100°C showed mainly CaO phases in XRD analyses and fairly stable with 7% loss in weight after treatment at 800°C. SEM images of samples calcined at 900°C were irregular compared to samples treated at 1100°C. EDX data revealed that the surface structure was 100% calcium and oxygen. GFEs are a potential source of pure calcium oxide for various industrial uses.展开更多
基金supported by the National Natural Science Foundation of China (Nos. 21822407 and 22074154)Youth Innovation Promotion Association CAS (2021420)the Foundation for Sci & Tech Research Project of Gansu Province (20JR10RA045 and 20JR5RA573)。
文摘Covalent organic frameworks(COFs), as an emerging class of porous crystalline materials constructed by covalent links between the building monomers, have gained tremendous attention. Over the past 15 years, COFs have made rapid progress and substantial development in the chemistry and materials fields. However, the synthesis of COFs has been dominated by solvothermal methods for a long time and it usually involves high temperature, high pressure and toxic organic solvents, which created many challenges for environmental considerations. Recently,the exploration of new approaches for facile fabrication of COFs has aroused extensive interest. Hence, in this review, we comprehensively describe the synthetic strategies of COFs from the aspects of nonconventional heating methods and reaction media. In addition, the advantages,limitations and properties of the preparation methods are compared. Finally, we outline the main challenges and development prospects of the synthesis of COFs in the future and propose some possible solutions.
基金The financial assistance from the Swedish International Development Agency for some of the study (travel grant for Valantine Mbatchou)
文摘Objetive: To explore the potential insecticidal, ovipositor deterrent and antifeedant effects of ethyl acetate extract of the seeds of Senna tora(Syn. Cassia tora) against cowpea weevil(Callosobruchus maculatus).Method: The activities were evaluated using standard protocols.In these bioassays, the cowpea seeds were used directly as an insect feed. The activity of the extract and isolated compounds were tested at concentrations of 100, 200 and 300 μg/mL and compared to neem oil and cinnamaldehyde(as standard positive controls). Phytochemical analysis of the ethyl acetate extract was done through a number of chromatographic techniques and the structures of the isolated compounds were established through comprehensive spectroscopic analysis including 2 D-NMR and ESI-MS studies.Results: Fractionation of the active ethyl acetate extract resulted in the isolation of one known anthraquinone,aurantio-obtusin(1) and a novel compound that was named as cassiatorin(2). Compounds1 and 2 showed comparable insect antifeedant properties with the positive controls while their insecticidal and ovipositor deterrent effects were far superior to the standard controls.Conclusions: It is thus concluded that Senna tora extracts and the isolated compounds(1 and2) may be employed in the postharvest management of stored cowpea seeds and as other crop protectants.
文摘In this paper, a novel series of bis [(aminoethyl)]-amine cationic lipid derivatives have been synthesized and identified to purity by NMR and Elemental analysis. B16-F0 cells were transfected with cationic lipid/pEGFP-N1 and cationic lipid/ß-gal lipoplexes complexed at +/- charge ratios of 1:1, 2:1, and 4:1. Dimyristoyl derivative showed highest activity at charge ratio 2:1 and both dimyristoyl and dioleoyl derivatives showed similar ß-gal activity at charge ratios 4:1. In 40 mM tris buffer pH 7.2 the dioleoyl derivative was able to fully complex with and retard pDNA at charge ratios above 2:1. None of the other lipid derivatives, dilauroyl, dimyristoyl, dipalmitoyl and distearoyl were able to fully neutralize the plasmid DNA at charge ratios similar to those used in the transfection experiment. The gel-to-liquid phase transition temperatures for dimyristoyl, dipalmitoyl and distearoyl were determined by a fluorescence anisotropy method to be 27.5°C, 32.5°C and 39°C, respectively. A gel-to-liquid crystalline phase transition temperature below 37°C, appears to be the crucial property that cationic lipids have to possess in order to mediate high levels of in vitro transfection activity in the absence of other helper lipids.
文摘This study investigated a natural indicator for acid-base titration which is extracted from guinea corn leaves popularly called “waakye leaves” in Ghana. Four types of acid-base titration were studied: strong acid versus (v/s) strong base, strong acid versus weak base, weak acid versus strong base, and weak acid versus weak base. The indicator color change, pH range and the average titre values were determined for each type of acid-base titration. These values were comparable to those obtained from three standard indicators: methyl orange, methyl red and phenolphthalein. Total flavonoids (TF) and condensed tannin (CT) from the crude leaves extract were determined which might be the major reasons for the activity of the extract as an indicator for simple acid-base titration. The authors suggest that the natural indicator is cheap, available, simple to extract, user and environmentally friendly and could be an excellent replacement for standard indicators.
文摘Novel type of polyethylene imine having methoxy (–OCH3) substituent azobenzene side chain group through eight methylene spacer group (PEI8M) was successfully synthesized and characterized by the polymer by 1H NMR, differential scanning calorimetry, polarized optical microscopic and X-ray diffraction analysis. Synthesized polymer possessed liquid crystalline (LC) properties. Spin coated PEI8M film showed out-of-plane molecular orientation on annealing and non-polarized visible light irradiation. PEI8M in solid film exhibited photoresponsive properties upon irradiation of UV and visible light. PEI8M film also exhibited reversible molecular orientation from random state to out-of-plane and from out-of-plane to random state on annealing, non-polarized UV and visible light irradiation.
文摘The effect of equal-channel angular pressing(ECAP) on the pitting corrosion resistance of anodized Al-Cu alloy was investigated by electrochemical techniques in a solution containing 0.2 mol/L AlCl3 and also by surface analysis.Anodizing was conducted for 20 min at 200 and 400 A/m2 in a solution containing 1.53 mol/L H2SO4 and 0.018 5 mol/L Al2(SO4)3·16H2O at 20 ℃.Anodized Al-Cu alloy was immediately dipped in boiling water for 20 min to seal the micro pores present in anodic oxide films.The time required before initiating pitting corrosion of anodized Al-Cu alloy is longer with ECAP than without,indicating that ECAP process improves the pitting corrosion resistance of anodized Al-Cu alloy.Second phase precipitates such as Si,Al-Cu-Mg and Al-Cu-Si-Fe-Mn intermetallic compounds are present in Al-Cu alloy and the size of these precipitates is greatly decreased by application of ECAP.Al-Cu-Mg intermetallic compounds are dissolved during anodization,whereas the precipitates composed of Si and Al-Cu-Si-Fe-Mn remain in anodic oxide films due to their more noble corrosion potential than Al.FE-SEM and EPMA observation reveal that the pitting corrosion of anodized Al-Cu alloy occurs preferentially around Al-Cu-Si-Fe-Mn intermetallic compounds,since the anodic oxide films are absent at the boundary between the normal oxide films and these impurity precipitates.The improvement of pitting corrosion resistance of anodized Al-Cu alloy processed by ECAP appears to be attributed to a decrease in the size of precipitates,which act as origins of pitting corrosion.
文摘In this study, we validated the effect of Moringa oleifera leaves as food supplement on poultry. Proximate neutron activation analysis was used in determining the level of some of the vital nutritional minerals and potential toxic elements in the serum of the birds during the experimental process, including Magnesium, Copper, Vanadium, Chlorine, Aluminum, Manganese, Calcium, Mercury, Cadmium, Arsenic, Sodium and Potassium. Incorporation of Moringa oleifera leaves in maize meal fed to poultry showed profound, statistically significant effect on their weight (p > 0.05) as well as intensity in coloration of the beaks and legs, combs and wattles, in contrast to a control (maize-meal only) feeding of broilers (p > 0.05). Moreover, a significant level of the biochemical minerals of serum Calcium (1.17 - 1.20 mmol·L-1), Sodium (141.6 - 152.6 mmol·L-1), Potassium (4.1 - 5.7 mmol·L-1), Chloride (95 - 110 mmol·L-1), Albumen (30 - 55 mmol·L-1) and Triglyceride (0.3 - 1.7 mmol·L-1) were observed in broilersfed with the formulated Moringa oleifera leaves and maize meal as compared to the maize meal only (control). Addition of Maringa oleifera leaves to poultry feed will lead to high output performance in poultry production.
文摘The effect of the application of oil from baobab seeds on the antioxidant capacity and stability of ascorbic acid in the fruit pulp at varying temperature were evaluated. Ascorbic acid analysis of the fruit pulp revealed that the concentration in the raw extract of the pulp sullied rapidly matched with the extract treated with the seed oil. Compared with the raw extracts the formulated fruit pulp presented the highest concentration of the total ascorbic acid when both samples were subjected to varying temperatures at extended time periods. The results clearly indicated the antioxidant enrichment property of the baobab seed oil. This study demonstrates the potential of oil derived from baobab seed as having antioxidant enrichment capacity and might be a potential ingredient in pharmaceutical cosmetics formulations and food preparations.
文摘Background: To contribute to a fuller appreciation of Ghana’s HIV epidemic, this paper presents various profiles of the Ghanaian HIV-affected household. To comprehensively tackle the HIV epidemic in Ghana, the profiles would provide stakeholders with ready information for policy formulation. Methods: We used data from a nationally representative survey that measured livelihood activities, household asset wealth, household composition, health, and nutrition variables of 1745 HIV-affected households. From these emerged various profiles. Results: About 50% of the households are headed by females. Households headed by men have an average size of three members, compared to two for female-headed households. There are far more AIDS widows than widowers. The annual death rate among the surveyed households was about 1000 per 100,000-households. Relatively more deaths occurred in male-headed households. Two-thirds of the households were asset poor. Various coping strategies were instituted by the households in reaction to threat of food insecurity. The national prevalence of chronic energy deficiency is 16%. Conclusions: Our data show that age of household head, hosting of a chronically ill member, and average size of household differed by sex of household head. The annual death rate of 1000 per 100,000 households is very high.
文摘Polyphenolic compounds with relatively high antioxidant activity obtained from subcritical water extraction of apple pomace were assessed for encapsulation by spray drying technique, making use of polymeric substances co-extracted with the polyphenolic compounds. Comparative assessments were carried out of the directly encapsulated subcritical water extract (SWE) products with particles formed when encapsulated with the addition of hydroxyl propyl-β-Cyclodextrin (SWE + HPβ-CD). The powders were characterized for their physico-chemical properties such as, moisture content, density, particle size, hygroscopicity to assess their suitability within cosmetic formulations. The SWE and SWE + HPβ-CD encapsulated products resulted in different physical properties. Although the particle size was less than 4 μm for both products, the direct encapsulation (SWE) was highly hygroscopic and this property was significantly reduced with addition of HPβ-Cyclodextrin (SWE + HPβ-CD). Scanning electron microscopy (SEM) and Fourier Transform Infrared (FT-IR) spectroscopic were em-ployed to analyse the micronised powders to support evidence of encapsulation. Both techniques revealed the interaction between compounds in extract and the carrier HPβ-Cyclodextrin suggesting successful encapsulation. The effect of storage conditions on retention of antioxidant activity of the subcritical water extract was evaluated within 35 days for extracts with and without the carrier HPβ-Cyclodextrin. Hydroxyl propyl-β-Cyclodextrin offered protection against degradation of antioxidant compounds thereby potentially extending the shelf-life and making the encapsulated powder suitable for incorporation in cosmetic and pharmaceutical applications.
文摘A highly selective ligand exchange type adsorbent was developed for the removal of trace arsenic(V) (As(V)) and phosphate from water. This adsorbent was prepared by loading zirconium(IV) on monophosphonic acid resin. This adsorbent was able to remove toxi canions efficiently at wide pH ranges. However, low pH was preferable for maximum breakthrough capacity in an adsorption operation.The effect of a large amount of competing anions such as chloride, bicarbonate, and sulfate on the adsorption systems of As(V) andphosphate anions was investigated. The experimental findings revealed that the As(V) and phosphate uptakes were not affiected by thesecompeting anions despite the enhancement of the breakthrough points and total adsorption. Phosphate anion was slightly preferablethan As(V) in their competitive adsorption by the adsorbent. The adsorbed As(V) and phosphate on the Zr(IV)-loaded resin werequantitatively eluted with 0.1 mol/L sodium hydroxide solution, and the adsorbent was regenerated by 0.5 mol/L sulfuric acid. Duringseveral cycles of adsorption-elution-regeneration operations, no Zr(IV) was detected in the column efluents. Therefore, the Zr(IV)-loaded monophosphonic acid resin is an effective ligand exchange adsorbent for removing trace concentrations of As(V) and phosphatefrom water.
文摘Eggshells are among the emerging hazardous waste from the food processing industry. This work sought to valorize waste guinea fowl eggshells. Guinea fowl eggshells (GFEs) were evaluated in the production of CaO for chemical and industrial application. The functionality, thermal stability, elemental composition, phase distribution and surface morphology properties of uncalcined GFEs and GFEs calcined at 700°C, 800°C, 900°C, 1000°C and 1100°C were systematically studied by FTIR, TGA, XRF, XRD and SEM-EDX respectively. The elemental analysis revealed Ca as the main element in the GFEs. The uncalcined GFEs showed intense peaks that corresponded to calcite (CaCO3) phases. These transformed into Ca(OH)2 as the temperature of calcination increased and finally to CaO in the FTIR analysis. In the XRD diffractograms, the main peaks at 2θ values were 29.466° for the uncalcined GFESs and at 37.377° for the sample treated at 1100°C. The phases were confirmed as CaO when compared with JCPDS files. Using the Scherer equation, the CaO crystallite size for the sample calcined at 1100°C was found to be 50.68 nm along the (2 0 0) orientation. All the samples showed multi-step decomposition patterns in the thermogravimetric analyses (TGA), with weight loss of up to 47% for the uncalcined GFEs sample, which was mainly due to the transformation of the calcite (CaCO3) phase to CaO by removal of bound water, organic components, and CO2. Samples calcined at 1100°C showed mainly CaO phases in XRD analyses and fairly stable with 7% loss in weight after treatment at 800°C. SEM images of samples calcined at 900°C were irregular compared to samples treated at 1100°C. EDX data revealed that the surface structure was 100% calcium and oxygen. GFEs are a potential source of pure calcium oxide for various industrial uses.
