The Essential Spectrum of a Sequence of Linear Operators in Banach Spaces

In this work we introduce some essential spectra $(\sigma_{ei}, i=1,...,5)$ of a sequence of closed linear operators $(T_{n})_{n\in\mathbb{N}}$ on Banach space, we prove that if $(T_{n})_{n\in\mathbb{N}}$ converges in the generalized sense to a closed linear operator $T$, then there exists $n_{0}\in \mathbb{N}$ such that, for every $n\geq n_{0}$, we have $\sigma_{ei}(\lambda _{0}-(T_{n}+B))\subseteq \sigma _{ei}(\lambda_{0}-(T+B)), i=1,...,5$, where $B$ is a bounded linear operator, and $\lambda _{0}\in \mathbb{C}$. The same treatment is made when $(T_{n}-T)$ converges to zero compactly.</p

Experimental Investigation on the Properties of a Recycled Aggregate Concrete Based on Waste of the Industrial Mineral Additions

This study investigates the possible effects of incorporating different industry wastes during manufacturing of concrete, with percentages ranging from 0% to 30%, and assesses the influence of these combinations (mineral additions and recycled aggregates) on the properties of a recycled concrete comprised of these two main constituents products. Recycled concrete samples with different combinations of mineral additions at various dosages were used to determine these properties in the fresh and hardened states. The ”Design-expert” methodology was used to analyse the results after 7, 14 and 28 days, identifying correlations and the effects of the different variables. The results obtained showed the advantageous effect of incorporating the pozzolana and slag into the concrete mixture at dosages of 15% and 30%, they also demonstrated the low optimal percentage of marble fillers of 5%. These findings suggest that replacing clinker with industrial waste could limit the dust and CO2 emissions into the atmosphere during concrete manufacture, offering environmental advantages as well as conserving the natural resources of aggregate recovery from C&amp;D wastes. Keywords: environmental concrete, mineral additions, recycled aggregate, design expert method

Optimization of Cellular Concrete Formulation with Aluminum Waste and Mineral Additions

The paper aims to study cellular concrete with a new approach of formulation without an autoclave, with the use of aluminum waste and incorporation of mineral additions into the sand and evaluate its physical and mechanical properties. In this experimental study, two types of cellular concrete are prepared, based on crushed and dune sand with the incorporation of 15% of the slag and 10% of pozzolana, as sand replacement. An experimental program was performed to determine the compressive strength at 28 days, the density and thermal conductivity of the confected cellular concrete. The obtained results showed that concretes prepared with crushed sand developed better mechanical resistance compared to the dune sand. It is also noted that the concretes containing the mineral additions provide a substantial increase in compressive strength in particular slag. Furthermore, cellular concretes with sand dunes offer better thermal conductivity, compared to those with crushed sand. The use of the additions reduces the Water/Binder (W/B) ratio and leads to a lower thermal conductivity regardless of the used sand nature. The outcome of the present study here in could present a modest contribution for the production of cellular concrete with local materials in particular dune sand, active mineral addition and aluminum waste. The physical and mechanical properties obtained from this new composition are estimated acceptable compared to those of the industry-prepared cellular concrete product. Doi: 10.28991/cej-2021-03091721 Full Text: PD

The Essential Spectrum of a Sequence of Linear Operators in Banach Spaces

In this work we introduce some essential spectra $(\sigma_{ei}, i=1,...,5)$ of a sequence of closed linear operators $(T_{n})_{n\in\mathbb{N}}$ on Banach space, we prove that if $(T_{n})_{n\in\mathbb{N}}$ converges in the generalized sense to a closed linear operator $T$, then there exists $n_{0}\in \mathbb{N}$ such that, for every $n\geq n_{0}$, we have $\sigma_{ei}(\lambda _{0}-(T_{n}+B))\subseteq \sigma _{ei}(\lambda_{0}-(T+B)), i=1,...,5$, where $B$ is a bounded linear operator, and $\lambda _{0}\in \mathbb{C}$. The same treatment is made when $(T_{n}-T)$ converges to zero compactly.</p

Study of the mechanical behavior and durability of mortars based on prepared sand

Sand occupies a great proportion of the cementitious matrix product and in particular mortars. Hence, the study of fine aggregates used for concrete and mortar in general, deserves to be objects of research including sand which has always been considered as inert material, whose role is exclusively physical. The study of mortars performances based on prepared sand to assess the effect of the type and rate of substitution of mineral additions pozzolana and blast furnace slag of a natural sand fine fraction (sieve diameter less than 0.16 mm) is seen as the main objective of the present experimental research work. The natural sand replaced size is less than 160 µm and for rheological reasons the maximum replacement rate of natural sand is limited to 10%. The results obtained show a significant improvement of the mechanical properties for the mortars based on the new activated sand. With regard to durability tests of HCl and H2SO4 acids chemical attacks, the substitution of the quartz by active mineral additions in the sand-size skeleton allows an advantageous reduction in loss of resistance up to 50% and a mass gain around 75%

Essential oils from three Algerian medicinal plants (Artemisia campestris, Pulicaria arabica, and Saccocalyx satureioides) as new botanical insecticides?

Medicinal and aromatic plants represent an outstanding source of green active ingredients for a broad range of real-world applications. In the present study, we investigated the insecticidal potential of the essential oils obtained from three medicinal and aromatic plants of economic importance in Algeria, Artemisia campestris, Pulicaria arabica, and Saccocalyx satureioides. Gas chromatography coupled with mass spectrometry (GC-MS) was used to study the essential oil chemical compositions. The three essential oils were tested against a mosquito vectoring filariasis and arboviruses, i.e., Culex quinquefasciatus, a fly pest acting also as pathogens vector, Musca domestica, and an agricultural moth pest, i.e., Spodoptera littoralis, using WHO and topical application methods, respectively. The essential oil from A. campestris, containing β-pinene (15.2%), α-pinene (11.2%), myrcene (10.3%), germacrene D (9.0%) (Z)-β-ocimene (8.1%) and γ-curcumene (6.4%), showed remarkable toxicity against C. quinquefasciatus (LC50 of 45.8&nbsp;mg&nbsp;L-1) and moderate effects (LD50 of 99.8&nbsp;μg adult-1) against M. domestica. Those from P. arabica and S. satureioides, containing epi-α-cadinol (23.9%), δ-cadinene (21.1%), α-cadinol (19.8%) and germacrene D-4-ol (8.4%), and thymol (25.6%), α-terpineol (24.6%), borneol (17.4%) and p-cymene (11.4%), respectively, were more active on S. littoralis showing LD50 values of 68.9 and 61.2&nbsp;μg larva-1, respectively. Based on our results, the essential oil from A. campestris may be further&nbsp;considered a candidate ingredient for developing botanical larvicides

Essential oils from three Algerian medicinal plants (Artemisia campestris, Pulicaria arabica, and Saccocalyx satureioides) as new botanical insecticides?

Medicinal and aromatic plants represent an outstanding source of green active ingredients for a broad range of real-world applications. In the present study, we investigated the insecticidal potential of the essential oils obtained from three medicinal and aromatic plants of economic importance in Algeria, Artemisia campestris, Pulicaria arabica, and Saccocalyx satureioides. Gas chromatography coupled with mass spectrometry (GC-MS) was used to study the essential oil chemical compositions. The three essential oils were tested against a mosquito vectoring filariasis and arboviruses, i.e., Culex quinquefasciatus, a fly pest acting also as pathogens vector, Musca domestica, and an agricultural moth pest, i.e., Spodoptera littoralis, using WHO and topical application methods, respectively. The essential oil from A. campestris, containing β-pinene (15.2%), α-pinene (11.2%), myrcene (10.3%), germacrene D (9.0%) (Z)-β-ocimene (8.1%) and γ-curcumene (6.4%), showed remarkable toxicity against C. quinquefasciatus (LC50 of 45.8&nbsp;mg&nbsp;L-1) and moderate effects (LD50 of 99.8&nbsp;μg adult-1) against M. domestica. Those from P. arabica and S. satureioides, containing epi-α-cadinol (23.9%), δ-cadinene (21.1%), α-cadinol (19.8%) and germacrene D-4-ol (8.4%), and thymol (25.6%), α-terpineol (24.6%), borneol (17.4%) and p-cymene (11.4%), respectively, were more active on S. littoralis showing LD50 values of 68.9 and 61.2&nbsp;μg larva-1, respectively. Based on our results, the essential oil from A. campestris may be further&nbsp;considered a candidate ingredient for developing botanical larvicides

Essential oils from three Algerian medicinal plants (Artemisia campestris, Pulicaria arabica, and Saccocalyx satureioides) as new botanical insecticides?

Medicinal and aromatic plants represent an outstanding source of green active ingredients for a broad range of real-world applications. In the present study, we investigated the insecticidal potential of the essential oils obtained from three medicinal and aromatic plants of economic importance in Algeria, Artemisia campestris, Pulicaria arabica, and Saccocalyx satureioides. Gas chromatography coupled with mass spectrometry (GC-MS) was used to study the essential oil chemical compositions. The three essential oils were tested against a mosquito vectoring filariasis and arboviruses, i.e., Culex quinquefasciatus, a fly pest acting also as pathogens vector, Musca domestica, and an agricultural moth pest, i.e., Spodoptera littoralis, using WHO and topical application methods, respectively. The essential oil from A. campestris, containing β-pinene (15.2%), α-pinene (11.2%), myrcene (10.3%), germacrene D (9.0%) (Z)-β-ocimene (8.1%) and γ-curcumene (6.4%), showed remarkable toxicity against C. quinquefasciatus (LC50 of 45.8&nbsp;mg&nbsp;L−1) and moderate effects (LD50 of 99.8&nbsp;μg adult−1) against M. domestica. Those from P. arabica and S. satureioides, containing epi-α-cadinol (23.9%), δ-cadinene (21.1%), α-cadinol (19.8%) and germacrene D-4-ol (8.4%), and thymol (25.6%), α-terpineol (24.6%), borneol (17.4%) and p-cymene (11.4%), respectively, were more active on S. littoralis showing LD50 values of 68.9 and 61.2&nbsp;μg larva−1, respectively. Based on our results, the essential oil from A. campestris may be further&nbsp;considered a candidate ingredient for developing botanical larvicides