28 research outputs found
Cytotoxic, Antimicrobial and Anti-oxidant Screening of Psidium Guajava Leaves Grown in Oman
No full textOxidative and peroxidative metabolism of pargyline and some related a-acetylenic amines : chemical and biological studies
No full textComparative notes on the Cushitic imperative
No full textIn the article, the author presents a comparative study between different Cushitic languages on affirmative imperative verbal forms.Qoraagu wuxuu maqaalkan ku soo bandhigayaa daraasaad isbarbardhig afeed oo ku saabsan qaababka fal amar ee afaf kala duwan oo ka mid ah afafka Kushitigga.Nell'articolo, l'autore presenta uno studio comparativo sulle forme verbali dell'imperativo affermativo in uso in diverse lingue cuscitiche
Efficiency of InN/InGaN/GaN Intermediate-Band Solar Cell under the Effects of Hydrostatic Pressure, In-Compositions, Built-in-Electric Field, Confinement, and Thickness
No full textThis paper presents a thorough numerical investigation focused on optimizing the efficiency of quantum-well intermediate-band solar cells (QW-IBSCs) based on III-nitride materials. The optimization strategy encompasses manipulating confinement potential energy, controlling hydrostatic pressure, adjusting compositions, and varying thickness. The built-in electric fields in (In, Ga)N alloys and heavy-hole levels are considered to enhance the results’ accuracy. The finite element method (FEM) and Python 3.8 are employed to numerically solve the Schrödinger equation within the effective mass theory framework. This study reveals that meticulous design can achieve a theoretical photovoltaic efficiency of quantum-well intermediate-band solar cells (QW-IBSCs) that surpasses the Shockley–Queisser limit. Moreover, reducing the thickness of the layers enhances the light-absorbing capacity and, therefore, contributes to efficiency improvement. Additionally, the shape of the confinement potential significantly influences the device’s performance. This work is critical for society, as it represents a significant advancement in sustainable energy solutions, holding the promise of enhancing both the efficiency and accessibility of solar power generation. Consequently, this research stands at the forefront of innovation, offering a tangible and impactful contribution toward a greener and more sustainable energy future.Dynamics of Micro and Nano System
Gas chromatographic determination of pargyline and pargyline amine metabolites after derivatization with isobutyl chloroformate
No full textAbstract
Pargyline (I) and four of its major amine metabolites, N-benzylpropargylamine (II), N-methylpropargylamine (IV), N-benzylmethylamine (VI) and pargyline N-oxide (VIII), were determined by g.l.c. after reaction with isobutyl chloroformate in a two-phase system. Pargyline and metabolite IV which form the same derivative, were separated quantitatively by liquid-liquid distribution before derivatization with isobutyl chloroformate. Also, metabolites VI and VIII form identical derivatives, and as they could not be easily separated, VIII was reduced to I before derivatization. The analytical method was applied in studies of the metabolism of pargyline in microsomes from phenobarbitone pretreated rats. The metabolism was rapid, leading mainly to the formation of II, IV, VI and VIII. 92% of the substrate was consumed during the first min of incubation at an initial substrate concentration of 100 μM (32 nmol mg−1 protein), and II, IV, VI and VIII accounted for 83% of formed metabolites. The metabolite II was further metabolized while the levels of IV, VI and VIII remained constant after 5 min. It was possible to determine 0.5 μM of pargyline, II and VI in microsomal incubations, with an r.s.d. of &lt;5% (n = 6). N-Methylpropargylamine (IV) was positively identified and quantitated as a pargyline metabolite for the first time.</jats:p
Reply to Heinschke, S.; Schneider, J.J. Comment on “Pashchanka, M. Conceptual Progress for Explaining and Predicting Self-Organization on Anodized Aluminum Surfaces. Nanomaterials 2021, 11, 2271”
No full textTeam Peyman Taher
Deciphering the Roles of Interspace and Controlled Disorder in the Bactericidal Properties of Nanopatterns against Staphylococcus aureus
No full textRecent progress in nano-/micro-fabrication techniques has paved the way for the emergence of synthetic bactericidal patterned surfaces that are capable of killing the bacteria via mechanical mechanisms. Different design parameters are known to affect the bactericidal activity of nanopatterns. Evaluating the effects of each parameter, isolated from the others, requires systematic studies. Here, we systematically assessed the effects of the interspacing and disordered arrangement of nanopillars on the bactericidal properties of nanopatterned surfaces. Electron beam induced deposition (EBID) was used to additively manufacture nanopatterns with precisely controlled dimensions (i.e., a height of 190 nm, a diameter of 80 nm, and interspaces of 100, 170, 300, and 500 nm) as well as disordered versions of them. The killing efficiency of the nanopatterns against Gram-positive Staphylococcus aureus bacteria increased by decreasing the interspace, achieving the highest efficiency of 62 ± 23% on the nanopatterns with 100 nm interspacing. By comparison, the disordered nanopatterns did not influence the killing efficiency significantly, as compared to their ordered correspondents. Direct penetration of nanopatterns into the bacterial cell wall was identified as the killing mechanism according to cross-sectional views, which is consistent with previous studies. The findings indicate that future studies aimed at optimizing the design of nanopatterns should focus on the interspacing as an important parameter affecting the bactericidal properties. In combination with controlled disorder, nanopatterns with contrary effects on bacterial and mammalian cells may be developedBiomaterials & Tissue BiomechanicsImPhys/Microscopy Instrumentation & TechniquesBT/BiocatalysisMicro and Nano Engineerin
Activerende Gevels: Naar gedrag beïnvloedende gebouwen
Get PDFAs a result of the large amounts of CO2 emissions the built environment produces, it contributes immensely to climate change. Within the strategies developed to reduce anthropogenic CO2 emissions, getting buildings to an energy-neutral level is one of the main priorities. The blueprint for this altered energy-efficient building now seems to be ready: the heavily insulated outer shells of buildings have decreased the demand for energy and the necessary coolness and warmth are induced using low-temperature systems.
Whether these changes are enough remains to be seen.
The actual, measured energy efficiency of these environmentally friendly buildings turns out to be lower than their theoretical efficiency; they use more energy than was expected up front. This difference can partly be attributed to the increased complexity of and sensitivity to improper use of these buildings. Users simply do not understand them well enough. Improper handling then turns into energy loss. Rebound effects also play a role in the lower levels of energy saving. The rebound effect states that as a result of higher efficiency, energy will relatively be cheaper. Lower energy bills will lead to a more increased use of warming and cooling, or to extra activities – whether or not polluting – outside the building.
The rebound effects make clear that environmentally friendly buildings do not automatically make their users less polluting; the energy efficiency of the building does not change people’s behaviour. One of the results of a survey that was conducted among 414 employees in five, energy efficient, and five more older, and less energy efficient office buildings in The Netherlands subscribes this. The environmental self-identity - which is regarded as the extent to which people perceive themselves to be a person whose actions are environmentally friendly – hardly differs from the office building users in both types of buildings (M = 4.977, SE = .069 vs. M = 5.052, SE = .075).
In order to reduce the rebound effects behaviour has to become more environmentally friendly. Changing behaviour sustainably is hard – because behaviour is based on routines - but it is not impossible.
Behaviour is influenced by values that are stable, transsituational and fairly abstract. When the contextual situation changes, these values and the (habitual) behaviour inherent to that specific situation can be re-evaluated. This implicates that in buildings, new contexts should be created: building should change in a more drastic and radical way than the evolutionary improvements made so far. Besides their energy efficiency the new energy efficient building differs little from their energy consuming predecessors.
The behaviour can also be changed by strengthen the environmental self-identity of people. Identity is the label with which somebody describes himself and it has a somewhat more flexible character than values have. For example, past behaviour is important for formulating one’s self-identity. It is seen as a cue to future behaviour. When somebody has shown environmentally friendly behaviour in the past, he is more likely to behave so in the future.
Changes in the context and ways to strengthen the environmental self-identity match the philosophy of among others Albert Borgmann who states that comfort, and the energy needed for it, will be more valuable when a user is more actively engaged in creating it. By being actively involved in sustainably creating an as ‘comfortable’ perceived indoor climate, people would feel they are behaving environmentally friendly, and having an environmental self-identity. Further, users would get the idea that they could act as a co-designer of that climate, as a result of which they would be more forgiving to it as well.
The increased environmental awareness resulting from this would then be the societal gain of a building that seduces its users to a more active involvement in creating the indoor climate. But why would users want to be seduced? In part, this could be attributed to the wish to control one’s living environment. Humans are comfort-seeking beings and when faced with discomfort, will find ways to remove that discomfort. Further, the ‘Theory of Planned Behaviour’ states that before behaviour is being performed, one will evaluate what that behaviour will bring as a return. In other words: will the behaviour lead to a positive or negative evaluation? It is obvious that the desired outcome is related to the professed values. So to be attractive to a diverse public, an activating building should appeal to different values.
Improving or sparing the environment alone is not enough however. Saving energy, having financial advantages, having greater control and an improved image can also play a role when choosing the systems, and the thereof arising behaviour.
This led to the following research question:
What effects does a façade system that activates its users have on their perception of thermal comfort, their satisfaction with the indoor climate, the use of energy and their environmental awareness?
Using an on the basis of this question designed activating, flexible, and adaptive façade (AfaF), a new context will be created in a test situation. Starting point is that however radical the facade to this end has to be, at the same time, one must be able to use it in an almost intuitive manner. In this way, the chances of making mistakes while using it will be minimized, and the chances to an actual and intensive use will be increased. When designing and materializing AfaF, the association with clothing is made. Just as when using clothes, extra layers of cloth are applied or removed when the situation inside or outside calls for it.
To test whether users actually see through this association, but also whether or not the increased control leads to an increased perception of thermal comfort and satisfaction with the indoor climate, a test pavilion was created. The herein assembled AfaF consisted of four layers: a water and wind proof layer, two insulating layers, and a sun-shielding layer with a low emission coefficient. One hundred and eighty one students and employees of the Hogeschool van Amsterdam, University of Applied Sciences (HvA) have participated in the tests; some of them were allowed to operate the AfaF, others were not.
The test results show that the test subjects with control over the AfaF saw it as an effective device to control the indoor climate. Next to effectiveness, one of the starting points in designing the AfaF was that it could be controlled intuitively. The time it cost the test subjects to manoeuvre the façade into the right configuration was thereby taken as a criterion. In the test unit with control over the AfaF, at the start of the test, the AfaF was purposely suspended in the wrong away, considering the outside conditions. The test subjects were then asked to re-configure the AfaF. On average, it cost them less than 5 seconds, which is lower than the ‘norm’. Furthermore, they strongly perceived the indoor climate they created to be a personal achievement.
Having control, however, seems to play out less strongly in experiencing comfort and satisfaction with the indoor climate. Only operating the AfaF a second time had a significant influence on the contentment with the indoor climate (F(1.85) = 8.168; p < .05; ƞ2 = .088). This contradicts other research that shows that control increases satisfaction. When prevailing temperatures are related to the perception of comfort and satisfaction with the indoor climate, however, both comfort and contentment turn out to score higher than was to be expected. Of the test subjects having control over the AfaF, 17% thought it was either too warm or too cold – which was lower than the test subjects without control scored (19.9%). The average perception of comfort in the test unit with control was slightly more positive than that in the test unit without control (M = 1.7; M = 1.8). Remarkable, however, is the low percentage of test subjects with control that were dissatisfied: 10.6%. And that even though the test pavilion did not have a conditioned indoor climate, and the indoor climate fluctuated with outside conditions that were rather cold. The use of a heater and a lamp, which were lined up in the test units, also shows that having control can have a positive influence on energy use. A significant relation was found between the re-operation of the AfaF and the turning off of the lamp (B = 1.590, SE = .512, p < .05, Exp (B) 4.904; R2 = .08). Further, the percentage of test subjects that turned on the stove in the unit with control was lower than the percentage of test subjects turning on the stove in the unit without control, respectively 25 to 34.7%. During these tests, the unit with control had a slightly less favourable climate then the unit without control. In 9 out of the 12 cases in which the heater was turned on, all options of using the AfaG to influence the indoor climate were exhausted. This form of energy saving can be regarded as ‘psychological’ energy saving – it feels more comfortable indoors than the temperatures actually justify. Using adaptive façades can, however, also lead to real energy saving. To determine how much can be saved, the software program VABI-elements was used to simulate a educational unit with the same dimensions and the same composition of the façade as the actual, physical test pavilion at the HvA. In the tests, cloths with varying thermal resistance, different masses and different emission coefficients were alternated. Starting from the layers with varying thermal resistance (wherein layers of Rc’s of 0.5; 1.5; 2.5; 3.5; 4.5; 6, and 8m2K/W were simulated with), a gain of 16.88% can be made when compared with a static façade with an RC of 8 m2K/W. To accomplish this, the user has to perform four acts only on a yearly basis: he must re-configure the façade cloths four times. When more acts are accepted, energy savings can go up to 20%. When the mass is made adaptive as well, 25% less energy is needed to realise a B-class indoor climate.
Further to these savings for the user – which will be regarded as an important motivation to start operating the façade - a broader societal goal was at the basis of the development of AfaF.
By operating the façade, users must get the idea that they are acting environmentally friendly, and this feeling must lead to a more environmentally friendly attitude. Not using the heater as much, and turning off the lamp in the unit with control over the AfaF points out that having control encourages environmentally friendly behaviour. To examine whether or not this behaviour would also extend to outside the building, the test subjects were asked to choose from two types of products: cheap, non-environmentally friendly products or 10% more expensive, but environmentally friendly products. Significant correlations were found between the environmental self-identity and the choice for environmentally friendly products with both students and non-students, the relationship between having control, and the chosen products was not found.
Having control has had a big influence on choosing a real reward, however. The goal for this last test was that ticking the box for, and thus accepting ‘a loss’ of 10% by choosing an environmentally friendly product, was rather noncommittal. The test subjects did not really have to pay for the products, after all. So, a month after the tests took place, a thank-you note was sent to all participants. Those that partook in the survey to discover the difference in perceived comfort, contentment with the indoor climate and the environmentally oriented self-identity of users of sustainable, and of older, less sustainable office buildings, received this e-mail as well. It stated that among all participants, four vouchers would be raffled. They were asked to make clear for what reward they would want to be considered: a Mediamarkt gift voucher, a travel voucher, a fair-trade basket, or an Oxfam Novib voucher.
Of all students, 87.4% chose a hedonistic reward – the Mediamarkt gift voucher, and the travel voucher. For students, €50 is a lot of money and their choice fits within the low cost theory that states that as soon as costs are perceived to be too high, sustainable behaviour will be abandoned. The difference between having control and not having control while choosing their reward was therefore scarcely found.
With non-students, however, significant differences were found between test subjects with and without control. The average amount of hedonistic vouchers chosen by nonstudents that were tested in the unit with control over the AfaF was considerably lower (16.7%) than the amount chosen by non-students in the unit without control (52.7%).
When the results are compared with those of HvA employees that did not participate in the tests, but did participate in the survey, it shows that operating the AfaF can have a positive influence on environmentally friendly behaviour. Of the HvA employees that were questioned, 65% chose a hedonistic Mediamarkt voucher and that is more than the non-students that had control in the test unit.
Thus, this research has determined and identified some forms of gains that could lead to the use of AfaF. To be able to define these gains as radical, however, the principles behind the activating, flexible and adaptive façade, the AfaF, eventually need to be embraced as well, and this can hardly be measured. What can be determined, however, is whether or not there is enough architectural leeway in the starting points of the AfaF to be able to give it architectural expression. Only then will the AfaF be interesting for architects. To examine this, a workshop was organized for seven architects who work at different Dutch architectural firms, and were asked to design an AfaF with an architectural character. The results show a large variety in adaptive and flexible possibilities of the façade, both in ways in which the users can be activated and in architectural expression that can be traced back to a very specific signature.
This research showed that an activating façade can initiate environmentally friendlier behaviour, and can be the first step towards a genuine reform of the built environment
Isolation, fractionation and identification of chemical constituents from the leaves crude extracts of Mentha piperita L grown in Sultanate of Oman
No full textABSTRACTObjectiveTo analyze and identify the chemical compositions of different organic plants crude extracts of Mentha piperita (M. piperita) grown in Sultanate of Oman by gas chromatography-mass spectrometry (GC-MS).MethodsThe powder sample was extracted with methanol by using Soxhlet extractor. Methanol crude extracts of M. piperita and its derived fractions of hexane, chloroform, ethyl acetate and butanol were prepared.ResultsQualitative analyses of various organic plant crude extracts of M. piperita by using GC-MS showed that majority of these compounds are bioactive.ConclusionsAccording to the results of the present study, the plant crude extracts could be used as medicine for the treatment of different diseases. The analysis and identification of the chemical compounds in the plant crude extracts by using GC-MS was the first time
Gas chromatography–mass spectrometry analysis and total phenolic contents of various crude extracts from the fruits of Datura metel L.
No full textAbstractDatura metel is considered as medicinal plants worldwide. Locally it is used as a traditional medicine due to its medicinal values. The objective of this present work is to identify the chemical ingredients and evaluation of total phenolics contents of different crude extracts from the locally grown D. metel. In vitro evaluation of total phenolics contents of different crude extracts was measured by established Folin–Ciocalteu reagents method. The identification of chemical ingredients was carried out in various crude extracts of D. metel by using sensitive gas chromatography–mass spectrometry (GC–MS). The results showed from different chromatogram that high percentage ingredients are high molecular weight ingredients such as polyphenolics and their derivatives, flavonoids, triterpeniods, hydrocarbons etc. The identified high percentage chemical ingredients present in the crude extracts are biologically active. The phenolic contents of crude extracts as gallic acid equivalents were found to be highest in chloroform followed by the order methanol>butanol>ethyl acetate>hexane extract. The identification of good number of chemical ingredients by spectrometry method in various crude extracts of D. metel fruits might have some ecological significance. In conclusion, chloroform crude extract contains highest phenolics content could be used as antibiotics
