Nisar Ullah, توقير احمد

كلية الكيميائيات والمواد-جامعة الملك فهد للبترول والمعادن · السعودية

The design and synthesis of seven chemosensors for Zn2+ detection in aqueous solutions are described. Chemosensors 1 and 2 contain dinitrophenol and 7-nitro-2,1,3-benzoxadiazole as a fluorophore, respectively. The fluorophores of both these chemosensors are attached to the 2,2'-dipicolylamine (DPA) receptor through 4,4'-oxydianiline. These sensors exhibited 3-fold and 2.4-fold enhancement in fluorescence intensity, respectively, upon the addition of 1 equiv. of Zn2+. Moreover, these sensors displayed higher selectivities for Zn2+ in the presence of other competing ions, displaying detection limits of 124 nM and 1.06 µM, respectively.Likewise, three new 1,8-naphthalimide-based fluorescent sensors (3-5) for Zn2+ detection in an aqueous solution were synthesized. The structural architect of these sensors contains a 1,8-naphthalimide scaffold as a fluorophore attached to 2,2’-dipicolylamine (DPA) and bis(2-quinolinylmethyl)amine (DQA) receptors through an amide linkage. The addition of Zn2+ to the solutions of sensors (3-5) led to enhanced fluorescence intensity, ranging between 2.5 to 14 folds. At physiological pH (pH = 7.4), these sensors exhibited high selectivities for Zn2+ in the presence of similar competing ions, displaying detection limits of 0.12 µM, 81.7 nM and 79.2 nM, respectively. This suggests their ability to detect the chronic concentration of Zn2+ for freshwater (>1.84 µM), designed by EPA (US). DFT simulations were performed on the more stable stacked conformations of unbound and Zn2+ bounded states of these sensors, which revealed that the latter display a higher density of excited states than the unbound sensors. Moreover, the stacked conformer of sensor 5 was significantly more stable as compared to sensors 3 and 4, which was attributed to a stronger Van Der Waals (VDW) interaction between DQA and 1,8-naphthalimide. The Zn2+ binding leads to enhanced electronic coupling between the HOMOs and LUMOs, making excited states more populated which then undergo geometric relaxation before emitting light and relaxing back to the ground states.In addition, this study describes the design and synthesis of two new fluorescent sensors 6 & 7 for the highly sensitive and selective detection of Zn2+. The synthesis of chemosensors 6 and 7 was accomplished through easy synthetic procedures in a high-yielding reaction sequence. Titration experiments were performed to measure the responses of sensors 6 and 7 to the varying concentrations of neat Zn2+ and Zn2+ in the presence of other bio-relevant metal ions (Cu2+, Cr2+, K1+, Mg2+, Fe3+, Pb2+, Mn2+, Co2+ and Cd2+), using UV and fluorescence spectroscopy. Extensive DFT simulations were performed to examine the impact of Zn2+ binding on the absorption spectra of 6 and 7. The synergistic coordination of the N-3 atom of 1,2,3-triazolyl function and 2,2-dipicolylamine (DPA) receptor unit with Zn2+ enables highly sensitive and selective detection of Zn2+, with a limit of detections (LOD) of 65.6 nM and 107 nM, respectively. At a physiological pH (pH = 7.4), the addition of Zn2+ to the solutions of 6 and 7 led to 4.7-fold and 6-fold enhancements in the fluorescence intensities, respectively. However, both sensors remain almost insensitive toward the competing ions. Job’s plot analysis suggests the formation of sensor/Zn2+ in 1:1. DFT simulations studies revealed that both sensors possess excellent binding with Zn2+. The total change in energy after the complexation was -86.6 for 6 and -89.3 for 7 hinting their high thermodynamic stabilities. In the unbound states, the highest occupied molecular orbital (HOMO) electronic density was localized onto the DPA receptor, used for the coordination with Zn2+ whereas the lowest unoccupied molecular orbitals (LUMOs) density was on the fluorophores. Upon coordination with Zn2+, however, the HOMOs and LUMOs were found to be localized on the fluorophores of 6 and 7. The insertion of dinitrobenzene in 6 exhibited higher fluorescence enhancement as compared to 7 upon binding to Zn2+.

Abdelghani Ikhlef, Chafia Serir, Nedjma Ouari

كلية التكنولوجيا-جامعة عبد الرحمان ميرة - بجاية · الجزائر

Cette étude a couvert l'ensemble du spectre des systèmes photovoltaïques, depuis leurs principes fondamentaux jusqu'aux défis technologiques actuels. Nous avons exploré les différentes technologies de cellules solaires, leurs caractéristiques et applications, ainsi que les méthodes de stockage d'énergie essentielles à leur efficacité.Notre recherche s'est concentrée sur la modélisation et l'optimisation des systèmes photovoltaïques. Le modèle à une diode a été choisi pour sa simplicité et son efficacité, permettant une caractérisation précise du générateur PV sous diverses conditions climatiques via Matlab/Simulink.L'étude a mis en évidence l'importance cruciale des méthodes MPPT, en particulier l'algorithme P&O et la logique floue, pour maximiser l'efficacité des systèmes. La modélisation d'un système complet intégrant panneaux solaires, batteries et charge variable a permis d'explorer les défis complexes de la gestion énergétique.L'algorithme de gestion proposé s'est révélé particulièrement efficace pour optimiser l'utilisation de l'énergie, assurant une alimentation stable tout en préservant la longévité des batteries. Les résultats démontrent la remarquable capacité du système à s'adapter aux fluctuations d'ensoleillement et de demande énergétique.L'intégration de la logique floue a considérablement amélioré la précision et la stabilité du système par rapport à l'algorithme P&O classique. Cette avancée ouvre la voie à une intégration plus efficace des énergies renouvelables dans le mix énergétique global.Contribue significativement à l'avancement des systèmes photovoltaïques autonomes, posant les bases pour le développement futur de solutions énergétiques durables et hautement efficaces. Malgré les progrès réalisés, des défis persistent, notamment en termes de rendement et de coûts initiaux, ouvrant ainsi de nouvelles perspectives pour la recherche future dans ce domaine en constante évolution.

باركة محمد الزين, شريف محمد

كلية العلوم الاقتصادية والعلوم التجارية وعلوم التسيير-جامعة أبو بكر بلقايد - تلمسان · الجزائر

عصام الخطيب, سالم عدلي محمود مصلح, محمد السبوع

كلية الدراسات العليا-جامعة النجاح الوطنية · فلسطين

هدفت هذه الدراسة إلى التعرف على واقع أطباء الأسنان في محافظة نابلس من حيث تدابير التخلص من النفايات الطبية الطرق الوقائية من العدوى والأمراض الناجمة عن الممارسات الطبية. تكونت عينة هذه الدراسة من 97 طبيب أسنان من أصل 134 يعملون في عيادات خاصة وأهلية وحكومية في محافظة نابلس حيث كانت نسبة الذكور 92.6%. تم جمع المعلومات باستبانة صممت لهذا الغرض ومن ثم تم تحليل المعلومات باستخدام الرزمة الاحصائية SPSS. فيما يتعلق بطرق التخلص من النفايات الطبية، بينت هذه الدراسة ان غالبية العيادات من عينة الدراسة تعمل على التخلص من نفاياتها عن طريق سلة المهملات (بقايا الحشوات 62.9%، الادوات الحادة 61.9%). وقد بينت نتائج الدراسة كذلك أن 45.6% من أطباء الأسنان يستعملوا دائماً القفازات خلال ممارستهم لعملهم، منهم 48.5% يستعملوا القفازات أثناء عمل حشوات الأملغم، و36.8% دائماً يضعون الأقنعة الواقية، و15.8% دائماً يضعون النظارات أثناء المعالجة و 74.2% طعموا ضد التهاب الكبد الوبائي نوع ب. كما تبين ان كما تبين أن ما نسبته 37.1% من أطباء الأسنان يشكون في كثيرا من الاحيان من التوتر و أن ما نسبته 48.4% يشكون من الصداع. اما فيما يتعلق بوسائل التعقيم المتبعة فقد تببن ان ما نسبته 83.2% منهم يستعملوا جهاز التعقيم الحراري الجاف و ان 53.6% يستعملوا الكحول كمادة معقمة.ان مثل هذه الممارسات لدليل واضح على المعرفة المحدودة او الاهمال في اتباع المعايير السليمة والمتبعة في هذا المجال. وأخيراً فقد تبين أن طرق التخلص من النفايات الطبية السنية وطرق التعقيم والإجراءات الوقائية وغيرها من السلامة المهنية والصحية المتبعة في معظم عيادات الأسنان في محافظة نابلس لم تكن بالقدر الكافي والفعال لذا لا بد من التدخل السريع من قبل الجهات المعنية بهدف زيادة الوعي الصحي والسلامة المهنية في عيادات طب الاسنان.

أماني عبده محمد , عمر محمد

جامعة الملك عبدالله للعلوم والتقنية · السعودية

In donor-acceptor systems, ultrafast interfacial charge transfer (CT), charge separation (CS) and charge recombination (CR), are among the key factors in determining the overall efficiency of the optoelectronic devices. In this regime, precise knowledge of the mechanisms of these processes on the femtosecond scale is urgently required. In this dissertation, using femtosecond transient absorption and mid-Infrared spectroscopies along with steady-state absorption and emission measurements, we are not only able to address the fundamental understanding of these ultrafast dynamical processes, but also control them at various inter- and intramolecular electron donor-electron acceptor systems. In the photoinduced intermolecular charge transfer systems, where donor and acceptor are separated from each other, three systems have been investigated; cationic poly[(9,9-di(3,3′-N,N′-trimethylammonium) propyl fluorenyl-2,7-diyl)-alt-co-(9,9-dioctyl-fluorenyl-2,7-diyl)] diiodide salt (PFN) conjugated polymer donor with 1,4-dicyanobenzene (DCB) acceptor, negatively charged porphyrin (POS) donor with positively charged (PFN) acceptor, and finally, positively charged (PFN) donor with negatively charged graphene carboxylate (GC) acceptor. Based on studying these three systems, we were able to explore some important factors and deriving forces including chemical structure, electrostatic interactions, energy band alignment, hydrogen bonding and solvents with different polarities and capabilities for hydrogen bonding that influence the rate and efficiency of the charge transfer at the interfaces of these donor-acceptor systems. For instance, unlike the conventional understanding of the key role of hydrogen bonding in promoting the charge-transfer process, our results reveal that the hydrogen-bonding increases the spacing between the donor and acceptor units which significantly hinders the charge-transfer process. On the other hand, in the photoinduced intramolecular charge transfer systems, where donor and acceptor are chemically attached to each other, we investigate the effects of conjugation length on photoinduced charge transfer in π-conjugated oligomers naphthalene diimide (NDI) end-capped oligo(phenylene ethynylene)s (PEn-NDI), and poly-(phenylene ethynylene) (PPE) donor backbone with (NDI) acceptor end-caps (PPE-NDI-n) systems. The results of femtosecond transient absorption and mid-IR spectroscopies show that the charge separation occurs on the 1-10 ps time scale with the rates decreasing as oligomer length increases in PEn-NDI system. In addition, in PPE-NDI-n system, the fluorescence quenching measurements indicate very efficient photoinduced electron transfer from the PPE backbone to the NDI end-groups, and the transfer efficiency increases with decreasing the number of units.Finally, the new physical insights reported in this thesis provide an understanding of several key variable components involved, thus paving the way toward the exploitation of efficient charge transfer at donor-acceptor interfaces, which is the key element and urgently required for optimal optoelectronic-device performance.

Belarouci Abdelghani, Bezzar A., Ghomari F., Khelidj A.

كلية التكنولوجيا-جامعة أبو بكر بلقايد - تلمسان · الجزائر

Le vieillissement des ouvrages en béton armé est le résultat de nombreuses agressions dues au milieu au sein duquel ils évoluent. Parmi les agents agressifs, les chlorures présents dans l’eau de mer ou les embruns salins, peuvent migrer dans le matériau béton, considéré comme un milieu poreux, par gradient de concentration pour atteindre les aciers qui sont dépassivés et par conséquent soumis au phénomène de la corrosion. La simulation au laboratoire de ce phénomène de diffusion est accéléré par divers moyens de mesure dont l’essai de migration normalisé selon la NT BUILD 492.L’objectif de ce travail de recherche est d’évaluer la résistance d’un béton ordinaire à la pénétration des ions chlores sous un champ électrique dans le cas d’un régime transitoire. Pour ce faire, des échantillons ont été confectionnés -à base de matériaux locaux- pour réaliser au laboratoire un programme d’essais qui nous a permis de déterminer leur coefficient de diffusion apparent.De plus, nous avons étudié l’influence de la température variant dans l’intervalle 0 à 40° C sur la diffusion des chlorures. Les résultats montrent bien que le coefficient de diffusion calculé est fortement dépendant de la variable température.

Daoud Lynda, Nabel Ahcene, Ouyahia El-Djida, Sofiane Fatmi

كلية التكنولوجيا-جامعة عبد الرحمان ميرة - بجاية · الجزائر

Lors de cette étude, nous nous sommes fixés comme objectif l’amélioration de la conservationdu sperme bovin. Ceci en passant par un objectif intermédiaire ; l’amélioration de la solubilité de lavitamine E en milieu aqueux. Pour cela, nous nous sommes intéressés à un vecteur particulier, leliposome.Cette étude a été menée en s'appuyant sur une modélisation en surface de réponse mise en œuvredans le cadre d'une planification expérimentale utilisant un plan d’expérience factoriel qui nous a permisde déterminer les valeurs optimales des facteurs choisis, à savoir ; le taux d’encapsulation et la taille desliposomes.Pour cela nous avons préparé plusieurs solutions liposomales que nous avons caractérisées parl’HPLC et MEB. Les résultats obtenus montrent que les meilleurs liposomes en termes de tauxd’encapsulation de la vitamine E (79 %) et de taille (99 nm) furent obtenus dans ces conditionsexpérimentales : 162 mg phospholipide, 25.5 mg cholestérol et 2 mg /ml vitamine E.La réfrigération du sperme bovin en utilisant les liposomes optimisés fut un échec, ce dernier estprobablement dû au milieu de dilution utilisé : le tampon tris qui dénature et déstabilise les solutionsliposomales préparées.

Abdessalem Benterki, Mohamed Zemir, Somia Boulesbaa, Mounia Yahi

كلية العلوم-جامعة الدكتور يحيى فارس بالمدية · الجزائر

خالد سليمان منحي, شجاح حسن حداد

كلية التربية-جامعة طيبة · السعودية

Mohammed Said Abutaha, Radwan Tahboub

جامعة بوليتكنك فلسطين · فلسطين

Nowadays, Cryptography plays a major role in protecting information. Hash function is a well defined procedure that digests a large data chunks into a small one. The returned value fromhash function is called hash code. Hash codes can be used for data integrity purposes while storing or transmitting data. It is well known that Hash algorithms work in one way and cannotbe reversed. Many hash algorithms and standards exist today, Among these algorithms, the Message Digest algorithms (MD4, MD5) and Secure Hash Algorithms (SHA1,SHA2 and SHA512). Since its invention by Lester S. Hill in 1929, the Hill cipher model which is one of the most famous symmetric cryptosystems that can be used to protect information from any unauthorized access. Hill cipher uses matrix operations to produce cipher matrix from a data and key matrices. Hill cipher requires the inverse of the key matrix for decryption. This inverse depends on asuggested modular number, but the matrix which doesn't have a prime determinant relative to a previous suggested number doesn't have an inverse. Non-invertible key matrix is the main problem of Hill Cipher. This problem leads to many other sub problems such as the disability of decrypting any encrypted text.In this research, we made use of the aforementioned problem in Hill cipher, namely the non invertible matrix problem, to design a novel one way hash algorithm. The first round of the proposed algorithm depends on the multiplication of non-invertible matrix with the plain text message in column vector. Then, we use the output of the first step to make a digest for thesedata chunks and generate the final hash value. A comparison between our practical one way hash algorithm and Message Digest (MD5), Secure Hash Algorithm (SHAI), and Secure Hash Algorithm ( SHA-512) has been made byusing the data size and matrix size factors to compare the time per second. Our algorithm'ssecurity power against brute force attacks and dictionary attack has been improved anddiscussed. We give a strong indication that our algorithm is resistant against collisions by using hamming distance algorithm. We also give a proof that our algorithm satisfies the one way has algorithm properties. Implementations of our algorithm and other algorithms shows that our algorithm has similar performance as MD5 algorithm for different matrix size, and it is more secure than MD5 against brute force attack and collision attacks, also our algorithm has a better performance than SHA 1IV