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Meteorological impacts on evapotranspiration in different climatic zones of Pakistan

Journal of Arid Land 2017年第6期9卷 938-952页

作者： Shahzada ADNAN Kalim ULLAh azmat h khan GAO Shouting Department of Meteorology COMSATS Institute of Information Technology Islamabad 44000 Pakistan Pakistan Meteorological Department Islamabad 44000 Pakistan State key Laboratory of Cloud-Precipitation Physics and SevereStorms Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China

Arid regions are highly vulnerable and sensitive to drought. The crops cultivated in arid zones are at high risk due to the high evapotranspiration and water demands. This study analyzed the changes in seasonal and annual evapotranspiration（ET） during 1951–2016 at 50 meteorological stations located in the extremely arid, arid, and semi-arid zones of Pakistan using the Penman Monteith（PM） method. The results show that ET is highly sensitive and positively correlated to temperature, solar radiation, and wind speed whereas vapor pressure is negatively correlated to ET. The study also identifies the relationship of ET with the meteorological parameters in different climatic zones of Pakistan. The significant trend analysis of precipitation and temperature（maximum and minimum） are conducted at 95% confidence level to determine the behaviors of these parameters in the extremely arid, arid, and semi-arid zones. The mean annual precipitation and annual mean maximum temperature significantly increased by 0.828 mm/a and 0.014℃/a in the arid and extremely arid zones, respectively. The annual mean minimum temperature increased by 0.017℃/a in the extremely arid zone and 0.019℃/a in the arid zone, whereas a significant decrease of 0.007℃/a was observed in the semi-arid zone. This study provides probabilistic future scenarios that would be helpful for policy-makers, agriculturists to plan effective irrigation measures towards the sustainable development in Pakistan.

关键词： evapotranspiration meteorological parameters climatic zone Penman Monteith method Pakistan

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Recent advances in titanium carbide MXene-based nanotextures with influential effect of synthesis parameters for solar CO_(2)reduction and h_(2)production:A critical review

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Journal of Energy Chemistry 2023年第1期76卷 295-331,I0008页

作者： Muhammad Tahir azmat Ali khan Sehar Tasleem Rehan Mansoor Areen Sherryna Beenish Tahir Chemical and Petroleum Engineering Department UAE UniversityP.0.Box 15551Al AinUnited Arab Emirates Balochistan University of Information Technology Engineering and Management Sciences(BUITEMS)QuttaBalochistanPakistan Department of Chemical Engineering School of Chemical and Energy EngineeringUniversiti Teknologi Malaysia81310UTM.Johor BahruJohorMalaysia Civil and Environmental Engineering Department UAE UniversityP.o.Box 15551Al AinUnited Arab Emirates

Photocatalytic solar to energy conversion is considered an attractive approach for overcoming energy crises and environmental ***,titanium carbide(Ti_(3)C_(2))MXenes have been recognized as promising cocatalysts based on their metallic conductivity,excessive active reaction sites,and enlarged surface *** current review focuses on the properties and applications of Ti_(3)C_(2)MXenes useful in the field of *** specifically,surface modification of Ti_(3)C_(2)MXenes by varying synthesis parameters to get pure materials and also composites with the role of functional groups towards solar energy conversion applications is highlighted in this *** effect of etching and oxidizing pathways to get an efficient cocatalyst has been discussed in *** the significant effect of parameters,optimum synthesis conditions such as etchant type,concentration,time and type of intercalant in both the Ti_(3)C_(2)synthesis approaches for improved photoactivity are ***,the surface modification of Ti_(3)C_(2)through oxidation for TiO2growth on its surface is deliberated with a detailed discussion on etchant type,concentration,etching time,and environmental *** optimum oxidation condition,including temperature,time,and environment for thermal treatment of Ti_(3)C_(2),were also ***,the review summarizes the conclusion and future perspectives for solar energy conversion applications.

关键词： Solar to energy conversion Ti_(3)C_(2)nanomaterials Termination groups MXene cocatalyst Synthesis parameters

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Photodetachment of h^- near a hard wall with arbitrary laser polarization direction

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Chinese Physics B 2015年第8期24卷 286-290页

作者： azmat Iqbal A.Afaq Department of Physics COMSATS Institute of Information Technology Centre of Excellence in Solid State Physics University of the Punjab New Campus

The photodetachment of h-near a hard wall is investigated with linear polarized laser light travelling in arbitrary direction θL with respect to the z axis. An analytical formula for the total cross section is derived using semi-classical closed orbit theory, which consists of two terms, i.e., the smooth background term and the oscillatory term with an extra factor 2(θL). This factor controls oscillations in the total photodetachment cross section. The amplitude of oscillation is maximum at θL = 0 when the laser polarization direction is perpendicular to the wall and it approaches zero at θL = π /2when the laser polarization direction is parallel to the wall. It is also observed that the total cross section depends on the source–wall distance and it reduces to a free space case when the wall is at infinite distance from the source.

关键词： quantum interference photodetachment process hard wall closed orbit theory

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Spectrokinetics study of probable effects of diverse inorganic ions on bleaching of dye

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Frontiers of Chemical Science and Engineering 2011年第1期5卷 131-138页

作者： Rafia azmat Masooda QADRI Fahim UDDIN Department of Chemistry Jinnah University for Women5C NazimabadKarachi 74600Pakistan Department of Chemistry University of KarachiKarachi 75270Pakistan

Toluidine blue(TB)is an important anticoagulant metachromasia molecule showing a pronounced variation in the visible spectrum due to the aggregation phenomenon and electrostatic interaction with the charged synthetic and biologic *** current study describes the interactive role of diverse inorganic material ions on the bleaching of toluidine blue(tolonium chloride)(TB^(+))with urea in acidic and basic media using the spectrophotometric *** spectra of TB and urea with different cations and anions were monitored and their characteristic features are presented *** negative effect of added cations on reduction may be the result of altered electron pathways which led to suppression of the reduction/bleaching of TB,while a slight decrease in dye reduction by added anions may be due to the scavenging of the Oh**** has been observed in the case of Co^(2+)that in addition to the electron-transfer reaction,other processes like layer and precipitate formation also appear to be taking *** dye bleaching process followed pseudo first order kinetics with respect to TB,urea,and h^(+)ion,whereas significant decoloration in the presence of urea proved that reductants control the redox *** decoloration in acidic medium with diverse ions was seen compared to alkaline media,showing that water ph played an important role in the bleaching of *** reduction/bleaching of dye was investigated at different temperatures,and energy parameters were evaluated for a TB^(+)-Urea reaction,including the energy of activation(Ea=39.60 kJ·mol^(–1)),enthalpy of activation(Δh#=34 kJ$mol^(–1)),entropy of activation(ΔS#=146.5 kJ mol^(–1)·K^(–1)),and free energy of activation(ΔG*=–52.35 kJ·mol^(–1)).A mechanism of interaction of diverse ions in dye bleaching and a mechanism of reduction based on the above findings is proposed.

关键词： TB diverse ions suppress decoloration

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Kinetics of Reduction of Thionine with Ribose and the Structural Properties of the Dye at Different ph Using DFT Method

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Chinese Journal of Chemistry 2011年第4期29卷 643-649页

作者： Ahmed, Khalid azmat, Rafia Uddin, Fahim Fatmi, M. Qaiser Department of Chemistry University of Karachi Karachi 752 70 Pakistan Department of Chemistry Jinnah University for Women Nazimabad Karachi Pakistan Department of Chemistry University of California at Riverside California 92521 USA

The reaction between the thionine （Th） and the ribose was observed spectrophotometrically and changes in absorbance of Th were recorded at variable concentration of dye, reductant and ph. A pseudo first order rate of reaction was found to establish the reduction kinetics of the dye, studied at a ph range of 0.34 to 12.8. Absorption spectrum of Th at different ph, with ribose showed a ph （12.8） dependent introversion. The reduction most probably took place with enediol intermediate of the sugar at high ph. A full geometry optimization of predominant species of Th namely, mono-deprotonated, di-deprotonated Th, and LTh （leuco thionine） respectively, at low and high ph, was performed at B3LYP level of theory. The data obtained from the energy minimization were in excellent agreement with other experimental and theoretical observations. The calculated enthalpies of formation for both reduction reactions （mono-deprotonated Th＋h＋→leucothionine and di-deprotonated Th＋2h＋→leucothionine） provided evidences for maximum reduction of the dye at high ph.

关键词： thionine ribose ph enediol geometry optimization reduction

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Thionine sensitized areobic photooxidation of thiourea in acidic medium

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Frontiers of Chemistry in China 2011年第2期6卷 120-126页

作者： Rafia azmat Nida SALEEM Department of Chemistry Jinnah University for WomenKarachi 74600Pakistan

An investigation of the thionine sensitized aerobic photooxidation of thiourea was observed spectrophotometrically at a wavelength of 598 *** reported two types of reactions which generally occur in the presence of oxygen:1)Singlet oxygen,produced by dye sensitization due to the hydrolysis that reacts with thiourea to form oxidative products like urea and other sulfur-containing fragments and 2)bleaching of dye,which leads to the *** rate of reaction in all studied parameters followed first order kinetics with respect to maximum absorption of the dye in the visible band *** kinetics was significantly dependent upon the medium and the reaction accelerated more rapidly at low ph.A direct relation was exhibited between the thiourea concentration and dye sensitizer,which was not pragmatic with the concentration of *** reaction was effected by the temperature,and the values of energy parameters suggested that the energy of activation was low while the entropy of activation increases with the rise in temperature,which indicated a highly solvated state of intermediate *** value of Δh* and ΔG*at elevated temperature showed that free energy is the driving force for the completion of reaction.A mechanism based on the above findings has been suggested.

关键词： thionine sensitized photo oxidation thiourea singlet oxygen fragment

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Quantum photodetachment of hydrogen negative ion in a harmonic potential subjected to static electric field

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Chinese Physics B 2019年第2期28卷 179-184页

作者： azmat Iqbal Kiran humayun Sana Maqsood Saba Jawaid Afaq Ahmad Amin Ur Rahman Bakht Amin Bacha Department of Physics The University of LahoreRaiwind Road CampusLahorePakistan Center of Excellence in Solid State Physics University of the PunjabLahorePakistan Department of Physics RIPHAH International University IslamabadPakistan Department of Physics University of Malakand Chakdara Dir(L)Pakistan

Photodetachment of negative ions has attracted immense interest owing to its fundamental nature and practical implications with regard to technology. In this study, we explore the quantum dynamics of the photodetachment cross section of negative ion of hydrogen h-in the perturbed one dimensional linear harmonic potential via static electric field. To this end,the quantum formula for total photodetachment cross section of the h-ion is derived by calculating the dipole matrix element in spherical coordinates. In order to obtain the detached electron wave function, we have solved the time-independent Schr¨odinger wave equation for the perturbed hamiltonian of the harmonic oscillator in momentum representation. To acquire the corresponding normalized final state detached electron wave function in momentum space, we have employed an approach analogous to the WKB(Wenzel–Kramers–Brillouin) approximation. The resulting analytical formula of total photodetachment cross section depicts interesting oscillator structure that varies considerably with incident-photon energy,oscillator potential frequency, and electric field strength as elucidated by the numerical results. The current problem having close analogy with the Stark effect in charged harmonic oscillator may have potential implications in atomic and molecular physics and quantum optics.

关键词： photodetachment cross section harmonic oscillator potential Stark effect time-independent Schrodinger equation WKB approximation

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Pre-oxidative catalytic treatment of toluidine blue with potassium permanganate in acidic solution

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Frontiers of Chemistry in China 2011年第2期6卷 84-90页

作者： Rafia azmat Faryal Vali MOhAMMED Tehseen AhMED Qurat-ul-Ain TANWIR Department of Chemistry University of KarachiKarachi 75270Pakistan International Chemical and Biological Sciences Center H.E.J Reaseach Institute of ChemistryUniversity of KarachiKarachi 75270Pakistan Department of Chemistry Jinnah University for WomenKarachi 74600Pakistan

This article describes the potential of KMnO4 for oxidation of the thiazine dye(Toluidine blue TB)in an acidic *** effect of different operational parameters like initial concentration of dye,potassium permanganate,ph,ionic strength,catalyst,acids and temperature were investigated spectrophotometrically at λ_(max)=613 *** results showed a complete removal of the TB with mineralization of the dye *** and complete decoloration was observed in the presence of monobasic acid(hCl)as compared to the h_(2)SO_(4) where little color removal was *** was found to be an effective catalyst in oxidation for complete and fast decolorization with *** significant change at elevated temperatures showed that an intermediate complex degraded with slight change in the ***/visible spectrophotometry and GC mass analysis showed an intermediate activated complex demethylated sulophooxide of TB which later on degraded into smaller fragments.

关键词： oxidation TB potassium permanganate decoloration Pb

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A new approach for reduction of methylene green withascorbic acid by de-oxygenation through carbondioxide

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Natural Science 2011年第7期3卷 566-572页

作者： Rafia azmat Noshab Qamar Raheela Naz 不详

Reduction kinetics of the methylene green (MG) with ascorbic acid (AA) in acidic medium at λmax 660 nm was monitored through visible spectrophotomtry in absence and presence of sodium carbonate. CO2 release through reaction of sodium carbonate and oxalic acid, created deoxygenated atmosphere for reduction of dye which greatly boosted the reaction rate. Initially slow reaction in presence of atmospheric oxygen proceeded rapidly when sodium carbonate was added. The reaction followed fractional order kinetics with AA and zero order kinetics with MG. The rate of reaction shows no linear dependence on [h+] concentration as an acidic medium. The rate of reaction is directly related with the elevated concentration of salt, which suggests that the two same charged species are involved in the rate determining step. Secondary reactions at elevated temperature showed complex kinetics.

关键词： Ascorbic Acid Methylene Green Sodium Carbonate Charged Species Secondary Reactions Elevated Temperature

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Kinetics and mechanisms of oxidation of d-fructose and d-lactose by permanganate ion in acidic medium

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Natural Science 2012年第7期4卷 466-478页

作者： Rafia azmat Raheela Naz Noshab Qamar Imran Malik Department of Chemistry University of Karachi Department of Chemistry Jinnah University for Women 5-C Nazimabad Karachi Pakistan International Centre of Chemical and Biological Sciences (ICCBS) University of Karachi

The oxidations of D-fructose and D-lactose were monitored spectrophotometrically by potassium permanganate in acidic medium at λmax 545 nm. Reaction demonstrated that the two oxidative species of permanganate were involved in an acidic oxidation of the sugars. It was established that respective acids of sugars as well as arabinonic and formic acid were the oxidation products. Respective acids of sugars were the results of reactive oxygen species of permanganate ions in acidic conditions while arabinonic and formic acids due to the cleavage of C__C bond through MnO-4 species. It was first order kinetics with respect to [MnO-4 ], [fructose], [lactose] and [h+]. hg was used to accelerate the slow oxidation of lactose. Effect of varying salt electrolyte concentration was insignificant showing that the molecular species was involved in the rate determining step. Formic and arabinonic acids and respective acids were analyzed through spot and spectroscopic studies respectively. Reaction was monitored at different temperatures and thermodynamics activation parameters were determined. A mechanism consistent with kinetic studies, spectral evidences, stoichiometry of the reactions and product analysis has been proposed for the oxidation of fructose and lactose in absence and presence of catalyst respectively.

关键词： Fructose Lactose KMnO4 hg Formic Acid Arabinonic Acid

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