The effects of different post-deposition annealing ambients (oxygen, argon, forming gas (95% N2 + 5% H2), and nitrogen) on radio frequency magnetron-sputtered yttrium oxide (Y2O3) films on n-type gallium nitride (GaN) substrate were studied in this work. X-ray photoelectron spectroscopy was utilized to extract the bandgap of Y2O3 and interfacial layer as well as establishing the energy band alignment of Y2O3/interfacial layer/GaN structure. Three different structures of energy band alignment were obtained, and the change of band alignment influenced leakage current density-electrical breakdown field characteristics of the samples subjected to different post-deposition annealing ambients. Of these investigated samples, ability of the sample annealed in O2 ambient to withstand the highest electric breakdown field (approximately 6.6 MV/cm) at 10-6 A/cm2 was related to the largest conduction band offset of interfacial layer/GaN (3.77 eV) and barrier height (3.72 eV).
Boron niride microflakes of 2-5 μm in diameter and greater than 40 μm in length with multilayer structure and highly crystalline nature are synthesized in two states of catalysts and dual role of nitrogen at 1100 °C. Most of the microflakes are flat, smooth and vertically aligned with a wall-like view from the top. Transmission electron microscopy shows overlapped layers of microflakes with an interlayer spacing of 0.34 nm. The h-BN components of the synthesized microflakes are verified from B 1s and N1 s peaks at 190. 7 and 397.9 eV. Raman shift at 1370 (cm(-1)) and sharp peaks in the XRD pattern further confirm the h-BN phase and crystalline nature of the synthesized microflakes. Microflakes of h-BN with the above characteristics are highly desirable for the development of a solid state neutron detector with higher detection efficiency.
In this work, we describe the genome of Lysinibacillus sp. strain A1, which was isolated from tropical soil. Analysis of its genome sequence shows the presence of a gene encoding for a putative peptidase responsible for nitrogen compounds.
Akumulasi logam berat dan bahan pencemar ke dalam ekosistem akuatik memberi impak negatif kepada alam sekitar dan organisma akuatik. Salvinia molesta dan Pistia stratiotes merupakan spesies yang mempunyai kadar pertumbuhan yang cepat dan berkemampuan dalam mengakumulasi logam berat dan menyerap nutrien menjadikan ia sesuai digunakan untuk merawat air sisa melalui kaedah bioteknologi iaitu fitoremediasi. Kajian ini dijalankan untuk menentukan kualiti air sisa kumbahan sebelum dan selepas rawatan menggunakan kaedah fitoremediasi. Selain itu, objektif kajian ini juga adalah untuk menilai keberkesanan Salvinia molesta dan Pistia stratiotes sebagai agen fitoremediasi bagi rawatan air sisa. Sampel tumbuhan akuatik berbeza berat iaitu 10, 20 dan 30 g diuji untuk rawatan tersebut. Ujian ANOVA satu hala menunjukkan perbezaan kadar pengurangan jumlah pepejal terampai dan ammoniakal nitrogen yang bererti (p<0.05) bagi 10, 20 dan 30 g Pistia stratiotes dan Salvinia molesta sepanjang kajian dijalankan iaitu daripada hari 0 sehingga hari ke-7. Keputusan kajian juga menunjukkan 30 dan 20 g Pistia stratiotes dan Salvinia molesta dapat menyingkirkan jumlah pepejal terampai dan ammoniakal nitrogen dengan lebih cepat berbanding berat tumbuhan 10 g. Ujian ANOVA satu hala juga tidak menunjukkan perbezaan yang bererti bagi kadar pengurangan jumlah pepejal terampai dan ammoniakal nitrogen antara Pistia stratiotes dan Salvinia molesta.
In this study, the potential of oil palm trunk (OPT) sap as a sole substrate for succinic acid (SA) production was evaluated using Actinobacillus succinogenes 130Z. After OPT sap was characterised, the effects of adding carbonate, yeast extract (YE) and minerals to this medium were investigated in an attempt to develop a low-cost fermentation medium. The OPT sap alone, gave comparable SA yield and productivity (0.54 g/g and 0.35 g/L/h) to those supplemented with YE (0.50 g/g and 0.36 g/L/h) and minerals (0.55 g/g and 0.40 g/L/h). The findings showed that OPT sap has sufficient amount of nutrients for SA biosynthesis by A. succinogenes 130Z and could potentially reduce cost without requiring expensive nutrients supplementation.
This study investigated the feasibility of integrated ammonium stripping and/or coconut shell waste-based activated carbon (CSWAC) adsorption in treating leachate samples. To valorize unused biomass for water treatment application, the adsorbent originated from coconut shell waste. To enhance its performance for target pollutants, the adsorbent was pretreated with ozone and NaOH. The effects of pH, temperature, and airflow rate on the removal of ammoniacal nitrogen (NH3-N) and refractory pollutants were studied during stripping alone. The removal performances of refractory compounds in this study were compared to those of other treatments previously reported. To contribute new knowledge to the field of study, perspectives on nutrients removal and recovery like phosphorus and nitrogen are presented. It was found that the ammonium stripping and adsorption treatment using the ozonated CSWAC attained an almost complete removal (99%) of NH3-N and 90% of COD with initial NH3-N and COD concentrations of 2500 mg/L and 20,000 mg/L, respectively, at optimized conditions. With the COD of treated effluents higher than 200 mg/L, the combined treatments were not satisfactory enough to remove target refractory compounds. Therefore, further biological processes are required to complete their biodegradation to meet the effluent limit set by environmental legislation. As this work has contributed to resource recovery as the driving force of landfill management, it is important to note the investment and operational expenses, engineering applicability of the technologies, and their environmental concerns and benefits. If properly managed, nutrient recovery from waste streams offers environmental and socio-economic benefits that would improve public health and create jobs for the local community.
Four porous coordination networks have been synthesized from 1,4-benzenedicarboxylate with Cl, Br, I, and NO2 substituents whose different spatial differences are sufficient to influence the coordination mode of adjacent carboxyl moieties to unlock an inter-penetrating framework to give isostructural structures. Their size and polarity differences account for the diverging CO2 adsorption performances.
Sewage sludge has long been regarded as a hazardous waste by virtue of the loaded heavy metals and pathogens. Recently, more advanced technologies are introduced to make use of the nutrients from this hazardous sludge. Successful recovery of sludge's carbon content could significantly convert waste to energy and promote energy sustainability. Meanwhile, the recovery of nitrogen and trace minerals allows the production of fertilizers. This review is elucidating the performances of modern thermal treatment technologies in recovering resources from sewage sludge while reducing its environmental impacts. Exhaustive investigations show that most modern technologies are capable of recovering sludge's carbon content for energy generation. Concurrently, the technologies could as well stabilize heavy metals, destroy harmful pathogens, and reduce the volume of sludge to minimize the environmental impacts. Nevertheless, the high initial investment cost still poses a huge hurdle for many developing countries. Since the initial investment cost is inevitable, the future works should focus on improving the profit margin of thermal technologies; so that it would be more financially attractive. This can be done through process optimization, improved process design as well as the use of suitable co-substrates, additives, and catalyst as propounded in the review.
A novel sequential flow baffled microalgal-bacterial (SFB-AlgalBac) photobioreactor was designed to cater for the synergistic interactions between microalgal and bacterial consortia to enhance nitrogen assimilation into microalgal biomass from nutrient-rich wastewater medium. The performance of the SFB-AlgalBac photobioreactor was found to be optimum at the influent flow rate of 5.0 L/d, equivalent to 20 days of hydraulic retention time (HRT). The highest microalgal nitrogen assimilation rate (0.0271 /d) and biomass productivity (1350 mg/d) were recorded amidst this flow rate. Further increase to the 10.0 L/d flow rate reduced the photobioreactor performance, as evidenced by a reduction in microalgal biomass productivity (>10%). The microalgal biomass per unit of nitrogen assimilated values were attained at 16.69 mg/mg for the 5.0 L/d flow rate as opposed to 7.73 mg/mg for the 10.0 L/d flow rate, despite both having comparable specific growth rates. Also, the prior influent treatment by activated sludge was found to exude extracellular polymeric substances which significantly improved the microalgal biomass settleability up to 37%. The employment of SFB-AlgalBac photobioreactor is anticipated could exploit the low-cost nitrogen sources from nutrient-rich wastewaters via bioconversion into valuable microalgal biomass while fulfilling the requirements of sustainable wastewater treatment technologies.
The vanadium (V) and nitrogen (N) dopants on TiO₂ demonstrated superior photocatalytic performance for the degradation of methylene blue (MB) dye under visible light. The vanadium, V, N-co-doped TiO₂ was synthesized by a modified sol-gel method. It revealed that V and N codoping had a significant effect on the band gap (Eg) of TiO₂, where the pristine TiO₂ possessed a wide band gap (3.18 eV) compared to V-doped TiO₂ (2.89 eV) and N-doped TiO₂ (2.87 eV) while the V, N-co-doped TiO₂ depicted the narrowest band gap (2.65 eV). The greatly increased specific surface area for the V, N-co-doped TiO₂ (103.87 m²/g) as compared to P25 TiO₂ (51.68 m²/g) also contributed to the major improvement in the MB dye degradation efficiency (0.055 min-1). The V, N-co-doped TiO₂ exhibit rapid photocatalytic activity for the degradation of MB with almost 99% of degradation in 120 minutes.
Leaf litter decomposition in a tropical stream was examined in two types of leaf packs; single species leaf packs of Pometia pinnata and two species leaf packs of equal combination of Pometia pinnata and Dolichandrone spathacea leaves. Both leaf packs were immersed in a river and weekly examined for remains of decomposed leaves and presence of EPT. In the control leaf packs, leaves in the two species leaf packs treatments decomposed within 35 days, faster than in single species leaf packs which decomposed after 42 days. In the presence of EPT, the leaf breakdown took 28 days in two species and 35 days for single species leaf packs. Higher abundance of EPT was observed in single species leaf packs but its diversity was higher in two species leaf packs. Litter breakdown in the stream was faster in the presence of EPT and softer leaves of D. spathacea with higher nitrogen content underwent faster decomposition and sustained higher numbers of EPT.
A study was carried out to determine the effect of enzyme concentration, temperature and incubation time of bromelain on nitrogen content (NC) and degree of hydrolysis (DH) of hydrolysate from cockle (Anadara granosa) meat wash water. Protein precipitation of cockle meat wash water was conducted at pH 4. The precipitate was then hydrolyzed using bromelain at concentrations of 0.5, 1.5 and 2.5% (enzyme/substrate). The best enzyme concentration was subsequently used to study the effect of incubation temperature at 30, 45 and 60°C. The best temperature was then used to determine the effect of incubation time at 0, 24 and 48 hours. Increasing bromelain concentration from 0 to 2.5% produced an increase in NC and DH. Similarly, increasing the incubation time from 0 to 48 hours also increased the value of NC and DH. However, while the increasing of incubation temperature from 30 to 60°C produced an increase in NC, no significant difference was observed for DH.
This paper presents a straightforward plasma treatment modification of graphene with an enhanced piezoresistive effect for the realization of a high-performance pressure sensor. The changes in the graphene in terms of its morphology, structure, chemical composition, and electrical properties after the NH3/Ar plasma treatment were investigated in detail. Through a sufficient plasma treatment condition, our studies demonstrated that plasma-treated graphene sheet exhibits a significant increase in sensitivity by one order of magnitude compared to that of the unmodified graphene sheet. The plasma-doping introduced nitrogen (N) atoms inside the graphene structure and was found to play a significant role in enhancing the pressure sensing performance due to the tunneling behavior from the localized defects. The high sensitivity and good robustness demonstrated by the plasma-treated graphene sensor suggest a promising route for simple, low-cost, and ultrahigh resolution flexible sensors.
Semiconductor thin films Copper Tin Selenide, Cu2SnSe3, a potential compound for solar cell applications or semiconductor radiation detector were prepared by thermal evaporation method onto well-cleaned glass substrates. The as-deposited films were annealed in flowing purified nitrogen N2, for 2 hours in a temperature range from 100˚C to 500˚C. The structure of as-deposited and annealed films has been studied by X-ray diffraction technique. The semi-quantitative analysis indicated from Reitveld refinement show that the samples composed of Cu2SnSe3 and SnSe. These studies revealed that the films were structured in mixed phase between cubic space group F-43m (no. 216) and orthorhombic space group P n m a (no. 62). The crystallite size and lattice strain were determined from Scherrer calculation method. The results show that increasing in annealing temperature resulted in direct increase in crystallite size and decrease in lattice strain.
Understanding of mass transfer kinetics is important for biosorption of nitrogen compounds from palm oil mill effluent (POME) to gain a mechanistic insight into future biological processes for the treatment of high organic loading wastewater. In this study, the rates of global and sequential mass transfer were determined using the modified mass transfer factor equations for the experiments to remove nitrogen by aerobic granular sludge accumulation in a sequencing batch reactor (SBR). The maximum efficiencies as high as 97% for the experiment run at [kLa]g value of 1421.8 h-1 and 96% for the experiment run at [kLa]g value of 9.6 × 1037 h-1 were verified before and after the addition of Serratia marcescens SA30, respectively. The resistance of mass transfer could be dependent on external mass transfer that controls the transport of nitrogen molecule along the experimental period of 256 days. The increase in [kLa]g value leading to increased performance of the SBR was verified to contribute to the future applications of the SBR because this phenomenon provides new insight into the dynamic response of biological processes to treat POME.
A huge amount of feathers is generated as a waste every year. Feathers can be a protein source if it is treated with an appropriate method. The present study investigates feasibility of autoclave alkaline and microwave alkaline pretreatments to be combined with enzymatic treatment for feather solubilization and protein production. Hydrolysis of chicken feather by autoclave alkaline pretreatment followed by an enzymatic method (AAS) or microwave alkaline pretreatment followed by an enzymatic method (MAS) was optimized by response surface methodology. Various NaOH concentrations for autoclave alkaline pretreatment (0.01-0.1 M) and microwave-alkaline pretreatment (0.01-0.05 M) were applied. The holding time for both pretreatments ranged from 1 to 10 min. The pretreated feathers were subjected to enzymatic hydrolysis using a commercial enzyme prior to analysis of protein content, feather solubilization, functional groups, and elemental composition (carbon, hydrogen, nitrogen and sulfur) of the treated feathers. The results revealed that both autoclave alkaline pretreatment and microwave alkaline pretreatment under optimized conditions of 0.068 M NaOH, 2 min holding time, 105 °C and 450 W, 0.05 M NaOH for 10 min, respectively, enhanced the subsequent Savinase hydrolysis of chicken feathers to achieve more than 80% degradation and more than 70% protein recovery. Fourier transform infrared spectroscopy results showed that both thermal-alkaline pretreatments weakened the structure of the feather. Reduction of carbon, nitrogen, and sulfur occurred in both thermal-alkaline pretreatments of feathers indicating degradation of the feather as well as protein release. Thermal-alkaline pretreatment may be a promising method for enhancing the enzymatic hydrolysis of chicken feathers and for producing a protein-rich hydrolysate.
Previous biochar research has primarily focused on agricultural annual cropping systems with very little attention given to highly fragile, complex and diverse natural alpine grassland ecosystems. The present study investigated the effect of biochar on the growth of alpine meadows and soil health. This study was conducted in the Qinghai Tibetan Plateau over a three year period to investigate the effect of three rice husk biochar application rates alone and combination with high and low NPK fertilizer dosages on alpine meadow productivity, soil microbial diversity as well as pH, carbon and nitrogen content at 0-10 cm and 10-20 cm depth. At the end of the 3rd year soil samples were analysed and assessed by combined analysis of variance. The results showed that biochar application in combination with nitrogen (N), phosphorus (P) and potassium (K) fertilizer had a significant increase in fresh and dry biomass during the second and third year of the study as compared to control and alone biochar application (p ≤ 0.05). Biochar alone and in combination with NPK fertilizer resulted in a significant increase in the soil pH and carbon contents of the soil. XPS results, the SEM imaging and EDS analysis of aged biochar demonstrated that the biochar has undergone complex changes over the 3 years as compared to fresh biochar. This research suggests that biochar has positive effect on alpine meadow growth and soil health and may be an effective tool for alpine meadow restoration.
Anggaran kuantiti dan pencirian fizikokimia sisa buangan makanan adalah pra-keperluan untuk mengoptimumkan proses pengkomposan. Satu tinjauan untuk menganggar jumlah sisa buangan makanan yang dijana oleh sektor komersial (n=10) dan isi rumah (n=50) di Bandar Baru Bangi telah dilakukan. Kehadiran komponen sisa nasi, sisa berasaskan daging, ikan, sayur-sayuran dan buah-buahan dan sisa buangan makanan basah yang lain juga diperiksa. Ciri fizikokimia sisa buangan makanan juga dianalisis. Jumlah sisa buangan makanan yang dijana di Bandar Baru Bangi dianggarkan sebanyak 11.41 MT sehari. Sektor isi rumah menyumbang 67.3% manakala sektor komersial menyumbang 32.7% daripada jumlah sisa buangan makanan yang dihasilkan. Kekerapan sisa buangan makanan berkeadaan basah adalah lebih tinggi (p<0.05) di sektor komersial berbanding sektor isi rumah. Sisa nasi merupakan komponen sisa buangan makanan yang paling kerap dijana oleh sektor isi rumah dan sektor komersial. Penilaian ciri fizikokimia menunjukkan nilai pH, kandungan abu, bahan organik, karbon organik, nitrogen dan lemak serta nisbah C/N adalah berbeza (p<0.05) antara sisa buangan makanan yang dijana pada hari yang berlainan. Sisa buangan makanan bersifat asid (pH 4.82-5.17) mempunyai kandungan air (65.9-69.5%) dan lemak yang tinggi (13.1-20.2%) tetapi kandungan nitrogen yang rendah (0.63-0.85%). Walau bagaimanapun, nisbah C/N masih berada dalam julat (20-25) yang sesuai untuk pengkomposan yang berkesan. Oleh yang demikian, dengan memperkenalkan proses pengkomposan, sisa buangan makanan berkenaan berpotensi digunakan sebagai kompos.
Bemisia tabaci (Gennadius) merupakan spesies lalat putih utama dan berbahaya kepada pertanian. Kajian telah dijalankan di Stesen MARDI Jalan Kebun, Klang, Selangor dari 9 September 2006 hingga 11 November 2007. Objektif kajian ini adalah untuk menilai kesan populasi lalat putih terhadap tanaman cili yang diberi kadar nitrogen yang berbeza (0, 33, 43, 53 g/pokok). Keputusan kajian menunjukkan pokok cili yang dibaja dengan kadar nitrogen yang tinggi menyebabkan peningkatan yang bererti (P<0.05) kepada populasi B. tabaci peringkat belum matang berbanding pada pokok cili yang dibajakan nitrogen pada kadar rendah. Min bilangan B. tabaci pada peringkat belum matang per aras kanopi adalah berbeza secara signifikan (P<0.05) antara aras kanopi dan antara perlakuan. Secara amnya, min bilangan telur dan larva B. tabaci adalah lebih tinggi secara bererti (P<0.05) pada aras kanopi atas berbanding tengah dan bawah. Walau bagaimanapun, min bilangan pupa B. tabaci adalah tinggi secara signifikan (P<0.05) pada aras kanopi bawah berbanding aras kanopi atas dan tengah. Min bilangan B. tabaci pada peringkat belum matang adalah berbeza secara bererti (P<0,05) mengikut minggu selepas pokok cili ditanam pada semua perlakuan. Secara amnya, populasi B. tabaci lebih tinggi semasa awal musim penanaman dan menurun selepasnya hingga ke akhir musim kecuali pada minggu ketiga dan ketujuh selepas pokok cili di tanam.
Kawasan Pentadbiran Putrajaya merangkumi 70% daripada kawasan tadahan Tasik Putrajaya. Kerja-kerja pembangunan yang dijalankan di dalam kawasan Putrajaya kebiasaannya dapat dikawal dengan merujuk kepada peraturan-peraturan dan garis panduan yang telah disediakan oleh pihak Perbadanan Putrajaya dalam memastikan kualiti air Tasik dan Tanah Bencah Putrajaya sentiasa mematuhi piawaian yang telah ditetapkan. Seluas 30% daripada kawasan tadahan Tasik dan Tanah Bencah Putrajaya terletak di luar pentadbiran dan kawalan pihak berkuasa Putrajaya. Kawasan tadahan Utara Putrajaya adalah kawasan tadahan yang luas yang menyumbang sebahagian besar air yang memasuki kawasan Tasik dan Tanah Bencah Putrajaya. Berasal dari anak Sg. Chuau kini ia telah membentuk satu kawasan tasik dan tanah bencah tersebut. Data kualiti air yang dilakukan oleh pihak berkuasa Putrajaya iaitu Perbadanan Putrajaya dari tahun 2002 sehingga 2005 dianalisis bagi mengenalpasti masalah utama kualiti air dari kawasan Tadahan Utara Tanah Bencah Putrajaya. Data kualiti air yang dicatat sepanjang tahun 2002 mendapati purata peratusan parameter yang melebihi standard Putrajaya bagi ammoniakal nitrogen (NH3-N) ialah 43.7%, E. coli 31.3%, TSS 12.5% manakala DO dan COD masing-masing 6.2%. Untuk sepanjang tahun 2003, purata peratusan parameter bagi NH3-N ialah 23.7%, E. coli 18.4%, jumlah koliform 18.4%, TSS 2.6%, DO 13.2%, COD 13.2%, dan BOD 10.5%. Untuk sepanjang tahun 2004, purata peratusan parameter bagi NH3-N ialah 35.5%, E. coli 22.6%, jumlah koliform 12.9%, TSS 9.7%, COD 3.2%, dan BOD 16.1%. Untuk tahun 2005, purata peratusan parameter bagi E. coli 36.4%, NH3-N ialah 22.7%, jumlah koliform 18.2%, BOD 13.6%, DO 4.5%, dan COD juga 4.5%. Secara keseluruhan, analisis bagi tempoh empat tahun ini mendapati parameter NH3-N dan E. coli sering kali menunjuk bacaan yang tidak mematuhi Piawaian Putrajaya. Punca utama masalah kualiti air di kawasan Tadahan Utara Tanah Bencah Putrajaya adalah kegagalan mengurus kawasan tadahan secara bersepadu dan sikap pihak berkepentingan di kawasan kajian tidak mengurus dan mengawal secara menyeluruh masalah air larian, kawasan terbuka dan kelodakan ketika membangunkan kawasan.