Tetraphenolate niobium and tantalum complexes for the ring opening polymerization of ε-caprolactone

Reaction of the pro-ligand α,α,α′,α′-tetra(3,5-di-tert-butyl-2-hydroxyphenyl-p-)xylene-para-tetraphenol (p-L¹H₄) with two equivalents of [NbCl₅] in refluxing toluene afforded, after work-up, the complex {[NbCl₃(NCMe)]₂(μ-p-L¹)}·6MeCN (1·6MeCN). When the reaction was conducted in the presence of excess ethanol, the orange complex {[NbCl₂(OEt)(NCMe)]₂(μ-p-L¹)}·3½MeCN·0.614toluene (2·3½MeCN·0.614toluene) was formed. A similar reaction using [TaCl₅] afforded the yellow complex {[TaCl₂(OEt)(NCMe)]₂(μ-p-L¹)}·5MeCN (3·5MeCN). In the case of the meta pro-ligand, namely α,α,α′,α′tetra(3,5-di-tert-butyl-2-hydroxyphenyl-m-)xylene-meta-tetraphenol (m-L²H₄) only the use of [Nb(O)Cl₃(NCMe)₂] led to the isolation of crystalline material, namely the orange bis-chelate complex {[Nb(NCMe)Cl(m-L²H₂)₂]}·3½MeCN (4·3½MeCN) or {[Nb(NCMe)Cl(m-L²H₂)₂]}·5MeCN (4·5MeCN). The molecular structures of 1–4 and the tetraphenols L¹H₄ and m-L²H₄·2MeCN have been determined. Complexes 1–4 have been screened as pre-catalysts for the ring opening polymerization of ε-caprolactone, both with and without benzyl alcohol or solvent present, and at various temperatures; conversion rates were mostly excellent (>96%) with good control either at >100 °C over 20 h (in toluene) or 1 h (neat)

Molybdenum (VI) imido complexes derived from chelating phenols : Synthesis, characterization and ɛ-Caprolactone ROP capability

Reaction of the bulky bi-phenols 2,2′-RCH[4,6-(t-Bu)₂C₆H₂OH]₂ (R = Me L¹ᵐᵉH₂, Ph L¹ᵖʰH₂) with the bis(imido) molybdenum(VI) tert-butoxides [Mo(NR¹)(NR²)(Ot-Bu)₂] (R¹ = R² = 2,6-C₆H₃-i-Pr₂; R¹ = t-Bu, R² = C₆F₅) afforded, following the successive removal of tert-butanol, the complexes [Mo(NC₆H₃ᵢ-Pr₂-2,6)₂L¹ᵐᵉ] (1), [Mo(NC₆H₃i-Pr₂-2,6)₂L¹ᵖʰ] (2) and [Mo(Nt-Bu)(μ-NC₆F₅)(L¹ᵐᵉ)]₂ (3). Similar use of the tri-phenol 2,6-bis(3,5-di-tert-butyl-2-hydroxybenzyl)-4-methylphenol (L²H₃) with [Mo(NC₆H₃ᵢ-Pr₂-2,6)₂(Ot-Bu)₂] afforded the oxo-bridged product [Mo(NC₆H₃i-Pr₂-2,6)(NCMe)(μ-O)L2H]₂ (4), whilst use of the tetra-phenols α,α,α′,α′-tetrakis(3,5-di-tert-butyl-2-hydroxyphenyl)-p- or -m-xylene L³ᵖH₄/L³ᵐH₄ led to {[Mo(NC₆H₃ᵢ-Pr₂-2,6)₂]₂(μ-L³ᵖ)} (5) or {[Mo(NC₆H₃ᵢ-Pr₂-2,6)₂]₂(μ-L³ᵐ)} (6), respectively. Similar use of [Mo(NC₆F₅)₂(Ot-Bu)₂] with L³ᵖH₄ afforded, after work-up, the complex {[Mo(NC₆F₅)(Ot-Bu)₂]₂(μ-L³ᵖ)}·6MeCN (7·6MeCN). Molecular structures of 1, 2·CH₂Cl₂, 3, 4·6MeCN, 6·2C₆H₁₄, and 7·6MeCN are reported and these complexes have been screened for their ability to ring open polymerize (ROP) ε-caprolactone; for comparative studies the precursor complex [Mo(NC₆H₃ᵢ-Pr₂-2,6)₂Cl₂(DME)] (DME = 1,2-dimethoxyethane) has also been screened. Results revealed that good activity is only achievable at temperatures of ≥100 °C over periods of 1 h or more. Polymer polydispersities were narrow, but observed molecular weights (Mn) were much lower than calculated values

Simulation of Flow Pattern through a Three-Bucket Savonius Wind Turbine by Using a Sliding Mesh Technique

Vertical axis wind turbine (VAWT) type Savonius rotor is self-starting, inexpensive, less technicality & high productivity wind machine, which can accept wind from any direction without orientation, and provides high starting torque. The investigations of aerodynamic parameters and the flow pattern of the turbulent flow through the rotor have high aspect on Savonius wind turbine performance. The flow pattern through a three buckets Savonius rotor model of 10cm diameter inside smoke wind tunnel with high-speed camera was investigated experimentally. The commercial code FLUENT 6.3.26 used to simulate the turbulent flow (M<0.3,Re>2000) by RNG K-e turbulent model. Two-dimensional model carried out the simulation of the flow pattern, velocities and pressures of airflow within a Savonius wind rotor placed in Smoke wind tunnel. The domain of the airflow dived for two zone, first zone up and down stream flow meshed by fixed structured grid generation. The second zone is around Savonius rotor; the flow pattern created by a pitched blade rotor was calculated by using a sliding mesh technique with unstructured grid generation. Three time steps between two blades of rotor is taken, which give three angular orientations of blades. The CFD results show good agree with experimental results of flow pattern. It is concluded that the sliding mesh method is suitable for the prediction of flow patterns around wind turbine. Then after ensured from the reliability of CFD simulation, it can be used for studying the velocity contour and the pressure distribution around the turbine

Molecular Study for Diagnosis of Ureaplasma parvum in Women with Recurrent Miscarriage

The objects of study is concerted to investigate the occurrence of Ureaplasma parvum in women with recurrent abortion and to determine the distribution of U. parvum serovars (1, 3, 6, 14) in women with recurrent abortion by conventional polymerase chain reaction (PCR) technique. In total, 130 samples included vaginal bleeding, vaginal swab, and urine, were collected from women with recurrent abortion and 40 samples included vaginal swab and urine from control women without recurrent abortion. Through the study, two types of media were used, Ureaplasma broth (IH Broth) and Ureaplasma agar (IH Agar). The positive isolates for Ureaplasma spp. were investigated by conventional PCR technique for identification of U. parvum and subtyping to their serovars (1, 3, 6, 14). The results revealed the U. parvum was identified in 29.6% from patient group and 11% from the control group. U. parvum isolates were further subtyped by using PCR, the results showed the serovar 3 was the most frequent isolate in proportion (42.8%), whereas serovar 1 (28.5%), serovar 6 (14.2%), and serovar 14 (14.2%) in patient group but in the control group only serovar 1 was isolated in rate (11%). These results evidently indicate that U. parvum may be an important etiologic agent for recurrent abortion

New pre-catalysts for ring opening of lactides/lactones based on earth abundant metals

In this study, a number of Nb, Ta, Mo, V, Al, Li and Zn complexes have been synthesised and fully characterised. The catalytic behavior of these pre-catalysts towards the ring opening polymerization (ROP) of the cyclic esters is discussed.Chapter 1 Presents an introduction to the history of polymers (from polyethylene to biodegradable polymers from cyclic esters), early discovery, mechanism of ring opening polymerisation and the use of vanadium, niobium, tantalum and molybdenum, aluiminium, lithium and zinc complexes as polymerization catalysts.Chpter 2 This chapter discussed results when the pre-ligands α,α,α’,α’-tetra(3,5-di-tert-butyl-2-hydroxyphenyl-p-)xylene-para-tetraphenol(p-L¹H₄) and α,α,α’,α’tetra (3,5-di-tert-butyl-2-hydroxyphenyl-m-)xylene-meta-tetraphenol (m-L²H₄) are reacted with a number of niobium and tantalum precursors such as [NbCl₅], [TaCl₅] or [Nb(O)Cl₃(NCMe)₂]. The resulting products {[NbCl₃(NCMe)]₂(μ-p-L¹)}·6MeCN (1·6MeCN), {[NbCl₂(OEt)(NCMe)]₂(μ-p-L¹)}·3½MeCN·0.614 toluene (2·3½MeCN·0.614 toluene), {[TaCl₂(OEt)(NCMe)]₂(μ-p-L¹)}.5MeCN (3·5MeCN), {[Nb(NCMe)Cl(m-L²H₂)₂]}·3½MeCN(4·3½MeCN) and {[Nb(NCMe)Cl(m-L²H₂)₂]}·5MeCN (4·5MeCN) were structurally characterized. Complexes 1–4 were screened as pre-catalysts for the ROP of ε-caprolactone, both with and without benzyl alcohol or solvent present, and at various temperatures.Chapter 3 In this chapter, the reaction of the bulky bi-phenols 2,2′-RCH[4,6-(t-Bu)₂C₆H₂OH]₂ (R = Me L³MeH₂, Ph L⁴PhH₂) with the bis(imido) molybdenum(VI) tert-butoxides [Mo(NR¹)(NR²)(Ot-Bu)₂] (R¹ = R² = 2,6-C₆H₃-i-Pr2; R¹ = t-Bu, R² = C₆F₅) has been studied. The complexes [Mo(NC₆H₃i-Pr₂-2,6)2L3Me] (5), [Mo(NC₆H₃i-Pr₂-2,6)2L⁴Ph] (6) and [Mo(Nt-Bu)(μ-NC₆F₅)(L³Me)]₂ (7) were isolated. Similar use of the tri-phenol 2,6-bis(3,5-di-tert-butyl-2-hydroxybenzyl)-4-methylphenol (L⁵H₃) with [Mo(NC₆H₃i-Pr₂-2,6)₂(Ot-Bu)₂] afforded the oxo-bridged product [Mo(NC6H₃i-Pr₂-2,6)(NCMe)(μ-O)L5H]₂ (8), whilst use of the tetra-phenols L¹pH₄/L²mH₄ led to {[Mo(NC₆H₃i-Pr₂-2,6)₂]₂(μ-L¹p)} (9) or {[Mo(NC₆H₃i-Pr₂-2,6)₂]₂(μ-L²m)}(10), respectively. Similar use of [Mo(NC₆F5)2(Ot-Bu)₂] with L¹pH₄ afforded {[Mo(NC₆F₅)(Ot-Bu)₂]₂(μ-L¹p)}·6MeCN (11·6MeCN). The molecular structures of 5, 6·CH₂Cl₂, 7, 8·6MeCN, 10·2C₆H14, and 11·6MeCN are reported. These complexes have been screened for their ability to act as catalysts for the ROP of ε-caprolactone; for comparative studies the complex [Mo(NC₆H₃i-Pr₂ 2,6)₂Cl₂(DME) (12) has also been screened.Chpter 4 This chapter focuses on the use of the vanadyl complexes. The new complexes [VO(Ot-Bu)L³] (13), {[VO(Oi-Pr)]₂(µ-p-L¹p)} (14) {[VO(OR)]₂(µ-p-L²m)} (R = i-Pr 15, t-Bu 16 have been prepared from [VO(OR)₃] (R = n-Pr, i-Pr or t-Bu) and the respective phenol, namely 2,2/-ethylidenebis(4,6-di-tert-butylphenol) (L³H₂) or Lp/mH4. For comparative studies, the known complexes [VO(µ-On-Pr)L³]₂ (18), [VOL⁶]₂ (19) (L6H₃ 2,6-bis(3,5-di-tert-butyl-2-hydroxybenzyl)-4-tert-butylphenol) were prepared. An imido complex {[VCl(Np-tolyl)(NCMe)]₂(μ-p-L¹p)} (17) has also been prepared. The molecular structures of complexes 13 – 19 are reported, and these complexes 13 – 19 have been screened for their ability to ring open polymerise ε-caprolactone, L-lactide or rac-lactide with and without solvent present. The co-polymerization of ε-caprolactone with L-lactide or rac-lactide was also studied.Chapter 5 describes the reaction of R¹R²CHN=CH(3,5-t-Bu₂C₆H₂-OH-2) (R¹ = R² = Me L⁷H; R¹ = Me, R² = Ph L⁸H; R¹ = R² = Ph L⁹H) with slightly greater than one equivalent of R³₃Al (R³ = Me, Et), which afforded the complexes [(L⁷⁻⁹)AlR³₂] (L⁷, R³ = Me 20, R³ = Et 21; L⁸, R³ = Me 22, R³ = Et 23; L³, R³ = Me 24, R³ = Et 25); complex 20 has been previously reported. Use of the N,O-ligand derived from 2,2/-diphenylglycine afforded either 24 or an amine by-product [Ph₂NCH₂(3,5-t-Bu₂C₆H₂-O-2)AlMe₂] (26). The known Schiff base complex [2-Ph₂PC₆H4CH₂(3,5-t-Bu₂C₆H₂-O-2)AlMe₂] (27) and the product of the reaction of 2-diphenylphosphinoaniline 1-NH₂,2-PPh₂C₆H₄ with Me₃Al, namely {Ph₂PC₆H₄N[(Me₂Al)₂µ-Me](µ-Me₂Al)} (28) were also isolated. For structural and catalytic comparisons, complexes resulting from interaction of Me₃Al with diphenylamine or benzhydrylamine, namely {Ph₂N[(Me₂Al)₂-Me]} (29) and [Ph₂CHNH(µ-Me₂Al)]₂·MeCN (30), were prepared. The molecular structures of the Schiff pro-ligands derived from Ph₂CHNH₂ and 2,2/-Ph₂C(CO₂H)(NH₂), together with complexes 24, 26 and 28 - 30·MeCN were determined. All complexes were screened for their ability to ROP ε-caprolactone, δ-valerolactone or rac-lactide, in the presence of benzyl alcohol, with or without solvent present.Chapter 6 describes the reaction of lithium alkoxides LiOR (R = t-Bu, Ph) with the acids 2,2/-Ph₂C(X)(CO₂H), where X = OH, NH₂, i.e. benzilic acid (2,2/-diphenylglycolic acid, benzH) or 2,2/-diphenylglycine (dpgH). In the case of benzH, reaction with one equivalent of LiOt-Bu in THF afforded the complex [Li(benz)(THF)]₂·2THF (31·2THF), which adopts a 1D chain structure. If acetonitrile is employed in the work-up under mild conditions, another solvate of 31 is isolated; use of LiOPh also lead to 31. Use of more robust work-up conditions afforded the complex [Li7(benz)7(MeCN)] (32·2MeCN·THF). Increasing the amount of LiOt-Bu (2 equivalents) led to the isolation of the complex {Li8(Ot-Bu)₂[(benz)](OCPh₂CO₂-CPh₂CO₂t-Bu)₂(THF)₄} (33). In the case of dpgH, use of two equivalents of LiOt-Bu in THF afforded [Li₆(Ot-Bu)₂(dpg)₂(THF)₂] (34), which contains an Li₂O₂ 6-step ladder. Similar reaction of lithium phenoxide with dpg afforded the complex [Li8(PhO)₄(dpg)₄(MeCN)₄] (35). The molecular structures of complexes 31 - 35 are reported; all were screened for their potential to act as pre-catalysts for ROP of ε-caprolactone (ε-CL), rac-lactide (r-LA) and δ-valerolactone (δ-VL).Chapter 7 describes the reaction of the dialkylzinc reagents R2Zn with the acids 2,2-Ph₂C(X)(CO₂H), where X = NH₂, OH, ie 2,2/-diphenylglycine (dpgH) or benzilic acid (benzH₂). With dpgH, the tetra-nuclear ring complexes [RZn(dpg)]₄, where R = Me (36), Et (37), 2-CF₃C₆H₄ (38), 2,4,6-F₃C₆H₂ (39) were isolated; complex 37 has been previously reported. The crystal structures of 36·2MeCN, 37 and 38·4(C7H8) ·1.59(H₂O) are reported, along with that of the intermediate compound (2-CF₃C₆H₄)₃B·MeCN and the known compound [ZnCl₂(NCMe)₂]. Complexes 36– 39, together with the known [(ZnEt)₃(ZnL)₃(benz)₃] (40; L = MeCN), have been screened, in the presence and absence of benzyl alcohol, for their potential to act as catalysts for the ROP of ε-caprolactone (ε-CL), δ-valerolactone (δ-VL) and rac-lactide (rac-LA); the co-polymerization of ε-CL with rac-LA was also studied.Chapter 8 This chapter presents the experimental section.Chapter 9 Appendix

Description and contrastive analysis of tense and time in English and Arabic

Summary available; p. xxxi - xxxii

Treatment with Dielectric Barrier Discharge (DBD) plasma restricts Aspergillus niger growth isolated from wheat grain

يؤثر التلوث الميكروبيولوجي بالفطر على جودة وسلامة تخزين حبوب القمح. تهدف هذه الدراسة إلى تقييم فاعلية البلازما الباردة في الحد من نمو فطريات الرشاشيات السوداء ( Aspergillus Niger )، وهو تلوث فطري معزول من حبوب القمح. أدى التفريغ  الكهربائي عبر حاجز عازل (DBD) الذي يعمل تحت الضغط الجوي إلى توليد البلازما الباردة المستخدمة في علاج فطريات الرشاشيات السوداء. تم التحقيق في تأثير بلازما DBD على فطريات الرشاشيات السوداء في فترات مختلفة (1 ، 2 ، 4 ، 6 ، و 15 دقيقة). أظهرت النتائج انخفاض معنوي كبير في نمو فطريات الرشاشيات السوداء ، و ايضا عدد الجراثيم مقارنة بالعينات غير المعاملة . أظهرت هذه الدراسة تقنية فعالة لتعزيز تخزين حبوب القمح ويمكن اعتبارها أساسًا لمزيد من الدراسات واسعة النطاق.Microbiological contamination by fungi impacts the quality and safety of wheat grain storage. This study aimed to evaluate the efficacy of cold plasma in restricting the growth of the fungus, Aspergillus niger, which was isolated from wheat grains. A dielectric barrier discharge (DBD) operating at atmospheric pressure generated cold plasma that was used to treat the fungus, and the impact of this treatment was investigated at various periods  1, 2, 4, 6, and 15 minutes. The results revealed a highly significant decrease in the growth and number of spores of Aspergillus niger compared to the controls. This study revealed an efficient technique for enhancing wheat grain storage that could be a foundation for further large-scale studies

Ring opening polymerization of lactides and lactones by multimetallic alkyl zinc complexes derived from the acids Ph₂C(X)CO₂2H (X = OH, NH₂ )

The reaction of the dialkylzinc reagents R₂Zn with the acids 2,2-Ph₂C(X)(CO₂H), where X = NH₂, OH, i.e. 2,2′-diphenylglycine (dpgH) or benzilic acid (benzH2), in toluene at reflux temperature afforded the tetra-nuclear ring complexes [RZn(dpg)]₄, where R = Me (1), Et (2), 2-CF₃C₆H₄ (3), and 2,4,6-F₃C₆H₂ (4); complex 2 has been previously reported. The crystal structures of 1·(2MeCN), 3 and 4·(4(C₇H₈)·1.59(H₂O)) are reported, along with that of the intermediate compound (2-CF₃C₆H₄)3B·MeCN and the known compound [ZnCl₂(NCMe)₂]. Complexes 1–4, together with the known complex [(ZnEt)₃(ZnL)₃(benz)₃] (5; L = MeCN), have been screened, in the absence of benzyl alcohol, for their potential to act as catalysts for the ring opening polymerization (ROP) of ε-caprolactone (ε-CL), δ-valerolactone (δ-VL) and rac-lactide (rac-LA); the co-polymerization of ε-CL with rac-LA was also studied. Complexes 3 and 4 bearing fluorinated aryls at zinc were found to afford the highest activities

Color image analyses using four deferent transformations (FFT-DCT-DWT-DMWT)

The transformation is the process that converts information from the spatial domain of the signal and translating it to another domain. the aim of  this paper is to compeer between four transformations are( discrete Fourier transform ,Discrete Cosine Transforms, Wavelet transform and discrete Multiwavelet transform). And there effective with color image. We determined and apply each transform on the image alone and study the effectiveness such as the noise, enhanesment, brightness, compretion, resolution beside the analyses then retrieving the image by applying the inverse of each transform. The performance of this technique has been done by computer using visual basic 6package. Keyword: image processing, spatial domain  ,DCT ,FFT ,DWT ,DMW