A return to common-sense: why ecology needs transcendental realism
- Authors: Price, Leigh
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/390324 , vital:68538 , xlink:href="https://doi.org/10.1080/14767430.2019.1580178"
- Description: Empirical realist ecologists, such as C. S. Holling, face significant methodological contradictions; for instance, they must cope with the problem that ecological models and theories of climate change, resilience and succession cannot make predictions in open systems. Generally, they respond to this problem by supplementing their empirical realism with transcendental idealism: they therefore say that their models are simply metaphorical or heuristic, that is, 'not true' in that they are not empirical. Thus, they explicitly deny an ontology for what their models are about. Nevertheless, in their practice, ecologists act as if their theories do have an ontology and thus tell us something truthful about the real world. This discrepancy leaves ecology vulnerable to unnecessary critique, such as that climate science is not real science. Transcendental realism offers a solution because it releases ecologists from the requirement to make predictions; but it does so without denying ontology. This provides several advantages to ecologists.
- Full Text:
- Date Issued: 2019
- Authors: Price, Leigh
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/390324 , vital:68538 , xlink:href="https://doi.org/10.1080/14767430.2019.1580178"
- Description: Empirical realist ecologists, such as C. S. Holling, face significant methodological contradictions; for instance, they must cope with the problem that ecological models and theories of climate change, resilience and succession cannot make predictions in open systems. Generally, they respond to this problem by supplementing their empirical realism with transcendental idealism: they therefore say that their models are simply metaphorical or heuristic, that is, 'not true' in that they are not empirical. Thus, they explicitly deny an ontology for what their models are about. Nevertheless, in their practice, ecologists act as if their theories do have an ontology and thus tell us something truthful about the real world. This discrepancy leaves ecology vulnerable to unnecessary critique, such as that climate science is not real science. Transcendental realism offers a solution because it releases ecologists from the requirement to make predictions; but it does so without denying ontology. This provides several advantages to ecologists.
- Full Text:
- Date Issued: 2019
Cordidepsine is A Potential New Anti-HIV Depsidone from Cordia millenii
- Zeukang, Rostanie D, Siwe-Noundou, Xavier, Fotsing, Maurice T, Mbafor, Joseph T, Krause, Rui W M, Choudhary, Muhammad I, Atchade, Alex de Theodore
- Authors: Zeukang, Rostanie D , Siwe-Noundou, Xavier , Fotsing, Maurice T , Mbafor, Joseph T , Krause, Rui W M , Choudhary, Muhammad I , Atchade, Alex de Theodore
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193988 , vital:45413 , xlink:href="https://doi.org/10.3390/molecules24173202"
- Description: Chemical investigation of Cordia millenii, Baker resulted in the isolation of a new depsidone, cordidepsine (1), along with twelve known compounds including cyclooctasulfur (2), lup-20(29)-en-3-triacontanoate (3), 1-(26-hydroxyhexacosanoyl)glycerol (4), glyceryl-1-hexacosanoate (5) betulinic acid (6), lupenone (7), β-amyrone (8), lupeol (9), β-amyrin (10), allantoin (11), 2′-(4-hydroxyphenyl)ethylpropanoate (12) and stigmasterol glycoside (13). Hemi-synthetic reactions were carried out on two isolated compounds (5 and 6) to afford two new derivatives, that is, cordicerol A (14) and cordicerol B (15), respectively. The chemical structures of all the compounds were established based on analysis and interpretation of spectroscopic data such as electron ionization mass spectrometry (EI–MS), high resolution electrospray ionization mass spectrometry (HR-ESI–MS), fast atom bombardment mass spectrometry (FAB–MS), one dimension and two dimension nuclear magnetic resonance (1D and 2D-NMR) spectral data as well as X-ray crystallography (XRC). Lupeol ester derivatives [Lup-20(29)-en-3-triacontanoate (3)], monoglycerol derivatives [1-(26-hydroxyhexacosanoyl)glycerol (4) and glyceryl-1 hexacosanoate (5)] were isolated for the first time from Cordia genus while sulfur allotrope [cyclooctasulfur (2)] was isolated for the first time from plant origin. Biological assays cordidepsine (1) exhibited significant anti-HIV integrase activity with IC50 = 4.65 μM; EtOAc extract of stem barks, EtOAc fraction of roots and leaves were not toxic against 3T3 cells.
- Full Text:
- Date Issued: 2019
- Authors: Zeukang, Rostanie D , Siwe-Noundou, Xavier , Fotsing, Maurice T , Mbafor, Joseph T , Krause, Rui W M , Choudhary, Muhammad I , Atchade, Alex de Theodore
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/193988 , vital:45413 , xlink:href="https://doi.org/10.3390/molecules24173202"
- Description: Chemical investigation of Cordia millenii, Baker resulted in the isolation of a new depsidone, cordidepsine (1), along with twelve known compounds including cyclooctasulfur (2), lup-20(29)-en-3-triacontanoate (3), 1-(26-hydroxyhexacosanoyl)glycerol (4), glyceryl-1-hexacosanoate (5) betulinic acid (6), lupenone (7), β-amyrone (8), lupeol (9), β-amyrin (10), allantoin (11), 2′-(4-hydroxyphenyl)ethylpropanoate (12) and stigmasterol glycoside (13). Hemi-synthetic reactions were carried out on two isolated compounds (5 and 6) to afford two new derivatives, that is, cordicerol A (14) and cordicerol B (15), respectively. The chemical structures of all the compounds were established based on analysis and interpretation of spectroscopic data such as electron ionization mass spectrometry (EI–MS), high resolution electrospray ionization mass spectrometry (HR-ESI–MS), fast atom bombardment mass spectrometry (FAB–MS), one dimension and two dimension nuclear magnetic resonance (1D and 2D-NMR) spectral data as well as X-ray crystallography (XRC). Lupeol ester derivatives [Lup-20(29)-en-3-triacontanoate (3)], monoglycerol derivatives [1-(26-hydroxyhexacosanoyl)glycerol (4) and glyceryl-1 hexacosanoate (5)] were isolated for the first time from Cordia genus while sulfur allotrope [cyclooctasulfur (2)] was isolated for the first time from plant origin. Biological assays cordidepsine (1) exhibited significant anti-HIV integrase activity with IC50 = 4.65 μM; EtOAc extract of stem barks, EtOAc fraction of roots and leaves were not toxic against 3T3 cells.
- Full Text:
- Date Issued: 2019
Deactivation of field cultivation in communal areas of South Africa: Patterns, drivers and socio-economic and ecological consequences
- Shackleton, Charlie M, Mograbi, Penelope, Drimie, Scott, Fay, Derick, Hebinck, Paul, Hoffman, Michael T, Maciejewski, Kristine, Twine, Wayne
- Authors: Shackleton, Charlie M , Mograbi, Penelope , Drimie, Scott , Fay, Derick , Hebinck, Paul , Hoffman, Michael T , Maciejewski, Kristine , Twine, Wayne
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/398210 , vital:69384 , xlink:href="https://doi.org/10.1016/j.landusepol.2019.01.009"
- Description: Smallholder production is a significant contributor to rural livelihoods and rural economies in much of the developing world. Yet, there is evidence of increasing disengagement in some regions, including southern Africa. However, there has been little consideration of the rates and the livelihood, ecological and policy implications of such. In this paper we examine previous studies on rates of deactivation of crop fields by smallholders in the communal areas of South Africa, supported by repeat photo images and case study material. Together these various methods show that it is a widespread phenomenon occurring at variable rates. Over short periods deactivation of crop fields can be balanced through some reactivation or intensification of homegardens. But over longer periods there is a net decline in the area of fields cultivated in many areas, with corresponding increases in the area of fallow land which, through time, may undergo changes towards more natural vegetation. We review the drivers of this deactivation of field cropping, and then contemplate the possible socio-economic and ecological implications at local and national scales. We show that there are numerous and profound implications that require greater understanding and policy responses.
- Full Text:
- Date Issued: 2019
- Authors: Shackleton, Charlie M , Mograbi, Penelope , Drimie, Scott , Fay, Derick , Hebinck, Paul , Hoffman, Michael T , Maciejewski, Kristine , Twine, Wayne
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/398210 , vital:69384 , xlink:href="https://doi.org/10.1016/j.landusepol.2019.01.009"
- Description: Smallholder production is a significant contributor to rural livelihoods and rural economies in much of the developing world. Yet, there is evidence of increasing disengagement in some regions, including southern Africa. However, there has been little consideration of the rates and the livelihood, ecological and policy implications of such. In this paper we examine previous studies on rates of deactivation of crop fields by smallholders in the communal areas of South Africa, supported by repeat photo images and case study material. Together these various methods show that it is a widespread phenomenon occurring at variable rates. Over short periods deactivation of crop fields can be balanced through some reactivation or intensification of homegardens. But over longer periods there is a net decline in the area of fields cultivated in many areas, with corresponding increases in the area of fallow land which, through time, may undergo changes towards more natural vegetation. We review the drivers of this deactivation of field cropping, and then contemplate the possible socio-economic and ecological implications at local and national scales. We show that there are numerous and profound implications that require greater understanding and policy responses.
- Full Text:
- Date Issued: 2019
Electrocatalytic Activity of Asymmetrical Cobalt Phthalocyanines in the Presence of N Doped Graphene Quantum Dots: The Push-pull Effects of Substituents
- Nkhahle, Reitumetse, Sekhosana, Kutloano E, Centane, Sixolile, Nyokong, Tebello
- Authors: Nkhahle, Reitumetse , Sekhosana, Kutloano E , Centane, Sixolile , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186904 , vital:44546 , xlink:href="https://doi.org/10.1002/elan.201800837"
- Description: A series of Co phthalocyanine (CoPc) derivatives and their respective nitrogen doped graphene quantum dot conjugates were used as catalysts towards the electrooxidation of hydrazine. Using a glassy carbon electrode as a support for the electrocatalysts, through cyclic voltammetry and chronoamperometry, the effects of combining the CoPcs with the nitrogen doped graphene quantum dots (NGQDs) were studied. The general observations made were that the NGQDs improve the catalytic activity of the CoPcs in both the p-p stacked and covalently linked conjugates by increasing the sensitivities and lowering the limits of detection with values as low as 0.43 mM being recorded.
- Full Text:
- Date Issued: 2019
- Authors: Nkhahle, Reitumetse , Sekhosana, Kutloano E , Centane, Sixolile , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186904 , vital:44546 , xlink:href="https://doi.org/10.1002/elan.201800837"
- Description: A series of Co phthalocyanine (CoPc) derivatives and their respective nitrogen doped graphene quantum dot conjugates were used as catalysts towards the electrooxidation of hydrazine. Using a glassy carbon electrode as a support for the electrocatalysts, through cyclic voltammetry and chronoamperometry, the effects of combining the CoPcs with the nitrogen doped graphene quantum dots (NGQDs) were studied. The general observations made were that the NGQDs improve the catalytic activity of the CoPcs in both the p-p stacked and covalently linked conjugates by increasing the sensitivities and lowering the limits of detection with values as low as 0.43 mM being recorded.
- Full Text:
- Date Issued: 2019
Fabrication of efficient nonlinear optical absorber using Zn phthalocyanine-semiconductor quantum dots conjugates
- Mgidlana, Sithi, Oluwole, David O, Nyokong, Tebello
- Authors: Mgidlana, Sithi , Oluwole, David O , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187496 , vital:44663 , xlink:href="https://doi.org/10.1016/j.poly.2018.11.024"
- Description: In this paper, we report on the synthesis of Zn(II) phthalocyanine derivatives and their conjugates with core/shell and core/shell/shell semiconductor quantum dots (SQDs). Zn(II) mono amino-carboxyethylphenoxy phthalocyanine (1), Zn(II) mono 3-carboxyphenoxy-tris(pyridin-2-yloxy) phthalocyanine (2) and Zn(II) mono aminophenoxy-tris(benzothiazole) phthalocyanine (3) were synthesized. The photophysical and optical limiting properties of the phthalocyanine (Pc) complexes and their conjugates with SQDs were investigated in dimethyl sulfoxide. The optical limiting behaviour of the Pc complexes and their conjugates were measured by the open aperture Z-scan technique at laser excitation wavelength of 532 nm with 10 ns pulse. The conjugates outperformed the Pc complexes alone with the conjugates of 2-SQDs affording highest nonlinear absorption coefficient (βeff) value of ∼80 cm/GW and lowest limiting threshold (Ilim) value of ∼0.27 J·cm−2 as compared to other samples while complex 1 gave low βeff and high Ilim values of 42.2 cm/GW and 1.39 J·cm−2, respectively.
- Full Text:
- Date Issued: 2019
- Authors: Mgidlana, Sithi , Oluwole, David O , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/187496 , vital:44663 , xlink:href="https://doi.org/10.1016/j.poly.2018.11.024"
- Description: In this paper, we report on the synthesis of Zn(II) phthalocyanine derivatives and their conjugates with core/shell and core/shell/shell semiconductor quantum dots (SQDs). Zn(II) mono amino-carboxyethylphenoxy phthalocyanine (1), Zn(II) mono 3-carboxyphenoxy-tris(pyridin-2-yloxy) phthalocyanine (2) and Zn(II) mono aminophenoxy-tris(benzothiazole) phthalocyanine (3) were synthesized. The photophysical and optical limiting properties of the phthalocyanine (Pc) complexes and their conjugates with SQDs were investigated in dimethyl sulfoxide. The optical limiting behaviour of the Pc complexes and their conjugates were measured by the open aperture Z-scan technique at laser excitation wavelength of 532 nm with 10 ns pulse. The conjugates outperformed the Pc complexes alone with the conjugates of 2-SQDs affording highest nonlinear absorption coefficient (βeff) value of ∼80 cm/GW and lowest limiting threshold (Ilim) value of ∼0.27 J·cm−2 as compared to other samples while complex 1 gave low βeff and high Ilim values of 42.2 cm/GW and 1.39 J·cm−2, respectively.
- Full Text:
- Date Issued: 2019
Inhibition of aluminium corrosion using benzothiazole and its phthalocyanine derivative
- Nnaji, Nnaemeka, Nwaji, Njemuwa, Fomo, Gertrude, Mack, John, Nyokong, Tebello
- Authors: Nnaji, Nnaemeka , Nwaji, Njemuwa , Fomo, Gertrude , Mack, John , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186949 , vital:44550 , xlink:href="https://doi.org/10.1007/s12678-019-00538-1"
- Description: Cyclic voltammetry and potentiodynamic polarization techniques were used to study the effects of 4-[4-(1,3-benzothiazol2yl)phenoxy] phthalonitrile (BT) and tetrakis[(benzo[d]thiazol-2ylphenoxy) phthalocyaninato] gallium(III)chloride (ClGaBTPc) as aluminium corrosion inhibitors in 1.0 M hydrochloric acid. The presence of the inhibitors in the concentration range of 2 to 10 μM was found to retard the aluminium corrosion process such that the inhibition efficiency was found to range from 28.2 to 76.1% for BT and from 71.5 to 82.7% for ClGaBTPc. The latter was a better inhibitor. Scanning electron microscopy and energy-dispersive X-ray measurements reveal effective metal surface protection by the inhibitors, most probably by shielding it from the corrosion attacks of Cl− from the acid. The calculated quantum chemical parameters agreed with experimental results.
- Full Text:
- Date Issued: 2019
- Authors: Nnaji, Nnaemeka , Nwaji, Njemuwa , Fomo, Gertrude , Mack, John , Nyokong, Tebello
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186949 , vital:44550 , xlink:href="https://doi.org/10.1007/s12678-019-00538-1"
- Description: Cyclic voltammetry and potentiodynamic polarization techniques were used to study the effects of 4-[4-(1,3-benzothiazol2yl)phenoxy] phthalonitrile (BT) and tetrakis[(benzo[d]thiazol-2ylphenoxy) phthalocyaninato] gallium(III)chloride (ClGaBTPc) as aluminium corrosion inhibitors in 1.0 M hydrochloric acid. The presence of the inhibitors in the concentration range of 2 to 10 μM was found to retard the aluminium corrosion process such that the inhibition efficiency was found to range from 28.2 to 76.1% for BT and from 71.5 to 82.7% for ClGaBTPc. The latter was a better inhibitor. Scanning electron microscopy and energy-dispersive X-ray measurements reveal effective metal surface protection by the inhibitors, most probably by shielding it from the corrosion attacks of Cl− from the acid. The calculated quantum chemical parameters agreed with experimental results.
- Full Text:
- Date Issued: 2019
Morphological identification of fungi associated with Eichhornia crassipes (Mart.-Solms) Laubach in the Wouri River Basin, Douala, Cameroon
- Voukeng, Kenfack S N, Coombes, Candice A, Weyl, Philip S, Djeugoue, F, Hill, Martin P
- Authors: Voukeng, Kenfack S N , Coombes, Candice A , Weyl, Philip S , Djeugoue, F , Hill, Martin P
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423785 , vital:72093 , xlink:href="https://doi.org/10.2989/16085914.2019.1636760"
- Description: In many parts of the world, excess growth of Eichhornia crassipes (Pontederiaceae) poses a serious threat to aquatic environments. In Cameroon, where manual clearing is still undertaken, little is known about fungal diversity associated with the plant, or its potential for biological control. Surveys of the Wouri River Basin in the Littoral Region of Cameroon were conducted during a rainy season (May–October 2014) and a dry season (November 2015–April 2016) at various sites, to identify fungi associated with water hyacinth. Fungi were isolated and identified from symptomatic plant parts collected. In the rainy season, 130 fungal isolates belonging to 12 genera were identified morphologically, whereas 299 isolates belonging to 23 genera were identified during the dry season. With the exception of Fusarium oxysporum and Phytophthora sp., the genera represented new records for Cameroon, and Chaetomium strumarium, Colletotrichum gloesporioides, C. acutatum, C. dematium, Curvularia pallescens and Pytomyces chartarum were considered new host records for E. crassipes in Africa. Isolates of Acremonium zonatum, Chaetomium strumarium, Alternaria eichhorniae, Phytophthora sp. and Rhizoctonia sp. showed the highest frequency of occurrence on E. crassipes in the Wouri River Basin and, given their record as plant pathogens, could be potentially useful in the development of mycoherbicides for this weed in Cameroon.
- Full Text:
- Date Issued: 2019
- Authors: Voukeng, Kenfack S N , Coombes, Candice A , Weyl, Philip S , Djeugoue, F , Hill, Martin P
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/423785 , vital:72093 , xlink:href="https://doi.org/10.2989/16085914.2019.1636760"
- Description: In many parts of the world, excess growth of Eichhornia crassipes (Pontederiaceae) poses a serious threat to aquatic environments. In Cameroon, where manual clearing is still undertaken, little is known about fungal diversity associated with the plant, or its potential for biological control. Surveys of the Wouri River Basin in the Littoral Region of Cameroon were conducted during a rainy season (May–October 2014) and a dry season (November 2015–April 2016) at various sites, to identify fungi associated with water hyacinth. Fungi were isolated and identified from symptomatic plant parts collected. In the rainy season, 130 fungal isolates belonging to 12 genera were identified morphologically, whereas 299 isolates belonging to 23 genera were identified during the dry season. With the exception of Fusarium oxysporum and Phytophthora sp., the genera represented new records for Cameroon, and Chaetomium strumarium, Colletotrichum gloesporioides, C. acutatum, C. dematium, Curvularia pallescens and Pytomyces chartarum were considered new host records for E. crassipes in Africa. Isolates of Acremonium zonatum, Chaetomium strumarium, Alternaria eichhorniae, Phytophthora sp. and Rhizoctonia sp. showed the highest frequency of occurrence on E. crassipes in the Wouri River Basin and, given their record as plant pathogens, could be potentially useful in the development of mycoherbicides for this weed in Cameroon.
- Full Text:
- Date Issued: 2019
Rebellion and revolution
- Authors: Tabensky, Pedro
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/305721 , vital:58606 , xlink:href="https://doi.org/10.1080/0969725X.2019.1574085"
- Description: In this piece I will focus on what I think is a central aspect of Albert Camus’s thinking, embodied in the distinction he makes in The Rebel between rebel and revolutionary. His is a philosophy of rebellion and he thinks that revolutions are a distorted expression of our need to rebel against that which we cannot accept. His views should serve as a counterpoint to those who think that an all-or-nothing approach to social change is desirable (those who, for instance, are too quick to justify murderous campaigns allegedly aimed at justice). And the issue here is not that embodied crudely in the reactionary (or conservative)/radical dichotomy. Rather, it is a defence of the need to rebel within limits, not so much to preserve the old against the threat of the new but, instead, to preserve basic human decency from the dark side of outrage, without dismissing what is crucial about outrage and emancipatory struggles.
- Full Text:
- Date Issued: 2019
- Authors: Tabensky, Pedro
- Date: 2019
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/305721 , vital:58606 , xlink:href="https://doi.org/10.1080/0969725X.2019.1574085"
- Description: In this piece I will focus on what I think is a central aspect of Albert Camus’s thinking, embodied in the distinction he makes in The Rebel between rebel and revolutionary. His is a philosophy of rebellion and he thinks that revolutions are a distorted expression of our need to rebel against that which we cannot accept. His views should serve as a counterpoint to those who think that an all-or-nothing approach to social change is desirable (those who, for instance, are too quick to justify murderous campaigns allegedly aimed at justice). And the issue here is not that embodied crudely in the reactionary (or conservative)/radical dichotomy. Rather, it is a defence of the need to rebel within limits, not so much to preserve the old against the threat of the new but, instead, to preserve basic human decency from the dark side of outrage, without dismissing what is crucial about outrage and emancipatory struggles.
- Full Text:
- Date Issued: 2019
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