On the Structure of ZnI2{\rm ZnI_2}

A new structure for ${\rm ZnI_2}$ is proposed which it exists in tetragonal state. In this structure the ${\rm ZnI_2}$ molecule exists in a nonlinear array and forms the basis of the tetragonal unit cell with one basis per unit cell. The structural analysis based on the reflections listed in ASTM 30-1479 shows that the proposed structure is correct.Comment: six pages and four figures. Manuscript prepared in RevTe

High field CdS detector for infrared radiation

New and highly sensitive method of detecting infrared irradiation makes possible solid state infrared detector which is more sensitive near room temperature than usual photoconductive low band gap semiconductor devices. Reconfiguration of high field domains in cadmium sulphide crystals provides basis for discovery

High field CdS detector for infrared radiation

An infrared radiation detector including a cadmium sulfide platelet having a cathode formed on one of its ends and an anode formed on its other end is presented. The platelet is suitably doped such that stationary high-field domains are formed adjacent the cathode when based in the negative differential conductivity region. A negative potential is applied to the cathode such that a high-field domain is formed adjacent to the cathode. A potential measuring probe is located between the cathode and the anode at the edge of the high-field domain and means are provided for measuring the potential at the probe whereby this measurement is indicative of the infrared radiation striking the platelet

COMPLETE CHARACTERIZATION OF BAGASSE OF EARLY SPECIES OF SACCHARUM OFFICINERUM-CO 89003 FOR PULP AND PAPER MAKING

Bagasse from early species of Saccharum officinerum-Co 89003 has 71.36% useful, long, and thick-walled fibers with good slenderness ratio, but the rigidity coefficient is less than that of Eucalyptus tereticornis and Leucaena leucocephala. The kink index and kink per mm length are lower in bagasse fiber than E. terticornis, which gives rise to fewer weak points in the fiber. Low alcohol–benzene soluble substances in bagasse induce less pitch problems and favor more homogeneity in the paper. Lignin content in bagasse is comparable to Eucalyptus globulus and Leucaena leucocephala, but α-cellulose, and pentosans are slightly lower. A higher proportion of carbon content compared to hydrogen and oxygen increases the energy value of bagasse. It produces 42.2% pulp yield of kappa number 28.2 at optimum cooking conditions, such as active alkali 12% (as Na2O), temperature 150oC, and time (at temperature) 60 min. An addition of 0.1% anthraquinone at the optimum condition improves pulp yield by 2.6% and mitigates kappa number by 3.9 units

Municipal Solid Waste Management in Debre Berhan City of Ethiopia

This paper presents an assessment of municipal solid waste generation and composition in Debre Berhan city in Ethiopia, providing an overview of the current state of municipal solid waste management, an analysis of the current problems in MSW collection, transportation, recycling and disposal, and few suggestions for improving the MSW in the coming years. Currently, waste composition in Debre Berhan is dominated by a high organic content, since the concentration of food and kitchen waste in urban solid waste makes up the highest proportion of the waste stream. The study revealed that only 25 % of the households have access to waste collection and transportation services as city municipality is under capacity to provide waste collection and transportation service.  98% of the respondents reported that recycling is not being practiced in the town. So, the potential of recycling and related activities is yet to be exploited. 75% of the urban dwellers dump the waste produce illegally and there exists no well designed dumping or landfill site, consequently urban dwellers are vulnerable to surface and groundwater pollution. Urgent and immediate improvement in building the capacities of the municipality is necessary to meet the current demand for improved municipal waste management and a number of recommendations are made aimed at improving the MSW management system. Keywords: Ethiopia, Waste Collection, Waste Disposal, Municipal Solid Waste Management

Biolixiviation des métaux lourds et stabilisation des boues municipales: effet de la forme du souffre élémentaire utilisé comme substrat

La présence de concentrations élevées en métaux lourds retrouvés dans les boues de stations d'épuration est un facteur important limitant ainsi leurs différents modes de dispositions (rejet en mer, enfouissement, incinération, ou même recyclage comme fertilisant agricole ou forestier) par crainte de dégâts considérables qui pourraient être causés à l'environnement. L'objectif de ce travail consistait à mettre au point un procédé qui permettrait conjointement la stabilisation des boues municipales et l'enlèvement des métaux lourds qui y sont associés. L'approche poursuivie dans cette étude était de vérifier si ce procédé microbien, conçu pour enlever les métaux lourds associés aux boues municipales, pourrait éventuellement remplacer les procédés conventionnels de stabilisation des boues municipales, ce qui réduirait considérablement les temps et coûts de traitement. Ce procédé microbien consiste à utiliser des souches de thiobacilles qui oxydent le soufre élémentaire, produisant ainsi de l'acide sulfurique, et par la même occasion une forte baisse de pH (1.5). Les résultats obtenus en cultures discontinues, en bioréacteurs, avec des boues primaires provenant de la station d'épuration de la Communauté Urbaine de Québec (C.U.Q.- Est) montrent que cette chute de pH entraîne une solubilisation importante des métaux (Cr: 56 %, Cu: 97 %, Fe: 30 à 40 %, Pb: 69 %, Zn: 98 % ), du phosphore (52 %), ainsi qu'une réduction appréciable des matières volatiles en suspension (40 à 50 % ), et ce, après seulement 7 jours de traitement. Le soufre nécessaire à la biolixiviation- stabilisation est introduit, dans le cas de notre étude, sous forme de granules ou de blocs. Ce choix de la forme de soufre influe beaucoup sur la qualité de la boue produite, ainsi que sur son pouvoir acidophile après neutralisation. Le soufre en blocs s'avère plus efficace et aussi préférable au soufre en granules quant au pouvoir acidophile, après neutralisation, de la boue produite.Given the potential geochemical mobility and recognizd toxicity of heavy metals, their presence at high concentrations in sewage sludges imposes serious limitations on various sludge disposal practices (ocean disposal, landfill, incineration, or use as a fertilizer in agriculture or forestry), The objectve of this work was to develop a process that would permit the simultaneous stabilization of sewage sludges and the removal of heavy metals associated with them. The approach followed was to verify if this microbial leaching procedure could eventually replace conventional sludge stabilization processes and hence considerably reduce the time and cost of treatment. The microbial process consists of using thiobacillus strains which, in the presence of air, oxidize elemental sulfur to sulfuric acid, thus reducing the pH to very acidic levels (pH 1.5). This biological oxidation of elemental sulfur is brought about by two groups of sulfur-oxidizing bacteria, the less-acidophilic and the acidophilic thiobacilli. The initial acid production and pH reduction is due to the less-acidophilic bactena (Thiobacillus thioparus) which lower the pH to about 4.0. This is followed by the growth of acidophilic bacteria (Thiobacillus thiooxidans) and fruther pH reduction.Batch culture experiments were carried out in 30 L and 8 L reactors with primary sludges obtained from the Quebec urban community's wastewater treatment centre. Elemental sulfur and inoculum were added at the beginning of each experiment The inoculum was prepared by adding 1 % tyndalized sulfur powder to fresh secondary sludge and incubating for 8 days (final pH 1.5 to 2.0). A small portion (5 %) of this acidified sludge was then used as an inoculum for another batch of fresh sludge and this process was repeated several times until an acclimatized inoculum was obtained which could oxidize elemental sulfur rapidly, without an appreciable lag phase. The elemental sulfur necessary as substrate for the simultaneous bioleaching and sludge stabilization was introduced in the form of granules (2.4 to 4 mm diameter) or blocks (25 mm diameter).Sludge pH and ORP were measured at 24 hour intervals and all other measurements were carried out at 48 hour intervals. The results demonstrate that the addition of elemental sulfur and inoculum resulted in a considerable lowering of the sludge pH during the incubation period. Such pH lowering was not observed in cultures to which sulfur and inoculum were not added. This lowering of pH (2.1) was related to the quantity of substrate (sulfur) and inoculum present in the medium. An increase in the medium ORP (from -50 to about 500 mV) was also observed. Acidification of the medium along with the elevated ORP levels resulted in the solubilization of metals initially present in the sludge. This pH reduction, after only 7 days of treatment, effected an important metal solubilization (Cr: 56 %, Cu: 97 %, Be: 30-40 %, Pb: 69 %, Zn: 98 %), as well as an appreciable reduction in phosphorus (52 %) and in the volatile suspended solids concentration (40-50 %). In addition, the sludge which initially had a highly repulsive odour was rendered odourless.In a previous study we had showm that for an optimum rate of acidification of the sludge a minimum concentration of elemental sulfur (2 g/L) was necessary, even though only 40 % of this sulfur was oxidized. In the present experiment the physical form of the sulfur was shown to influence both the quality of sludge produced and its acid-generating capacity after neutralization. Sulfur in the form of blocks was more efficient than granules in that the elemental sulfur could be readily separated from the sludge at the end of the treatment, yielding a sludge after neutralization that had a low acid-generating capacity. In the case of granules, the unused sulfur was broken down into a fine powder during the course of the bioleaching experiment and could not be separated from the leached sludge - even after neutralization, the leached sludge exhibited a high acid-generating capacity, which would limit its use as a fertilizer on agricultural land

STUDIES ON HIBISCUS CANNABINUS, HIBISCUS SABDARIFFA, AND CANNABINUS SATIVA PULP TO BE A SUBSTITUTE FOR SOFTWOOD PULP- PART 2: SAS-AQ AND NSSC-AQ DELIGNIFICATION PROCESSES

Hibiscus cannabinus, Cannabis sativa, and Hibiscus sabdariffa, fast growing productive annual plants, could provide fiber necessary to partially alleviate the world’s fiber deficit. The present study aimed at producing high yield pulp and the best mechanical strength properties with minimum impact on environment by SAS-AQ, and NSSC-AQ pulping processes. A total alkali of 13% (as Na2O), an alkali ratio of 0.80, and a Na2SO3 charge 11.70% (as Na2O) were found optimum to reduce maximum kappa number. A lower kappa number and good strength properties were achieved by increasing total alkali and Na2SO3 charge. SAS-AQ pulps showed good response towards CEHH bleaching. The NSSC-AQ pulping was conducted at a total alkali charge of 8% (as Na2O) by varying the ratio of sulphite-to-carbonate (100:0-0:100), and cooking time (60-120 min) at 1600C. A ratio of sulphite-to-carbonate 60:40 was suitable for corrugating medium (cooking time 60 min), while a ratio of sulphite-to-carbonate 70:30 showed better strength properties (longer cooking time)

Rotational Dynamics of Organic Cations in CH3NH3PbI3 Perovskite

Methylammonium lead iodide (CH3NH3PbI3) based solar cells have shown impressive power conversion efficiencies of above 20%. However, the microscopic mechanism of the high photovoltaic performance is yet to be fully understood. Particularly, the dynamics of CH3NH3+ cations and their impact on relevant processes such as charge recombination and exciton dissociation are still poorly understood. Here, using elastic and quasi-elastic neutron scattering techniques and group theoretical analysis, we studied rotational modes of the CH3NH3+ cation in CH3NH3PbI3. Our results show that, in the cubic (T > 327K) and tetragonal (165K < T < 327K) phases, the CH3NH3+ ions exhibit four-fold rotational symmetry of the C-N axis (C4) along with three-fold rotation around the C-N axis (C3), while in orthorhombic phase (T < 165K) only C3 rotation is present. Around room temperature, the characteristic relaxation times for the C4 rotation is found to be ps while for the C3 rotation ps. The -dependent rotational relaxation times were fitted with Arrhenius equations to obtain activation energies. Our data show a close correlation between the C4 rotational mode and the temperature dependent dielectric permittivity. Our findings on the rotational dynamics of CH3NH3+ and the associated dipole have important implications on understanding the low exciton binding energy and slow charge recombination rate in CH3NH3PbI3 which are directly relevant for the high solar cell performance

Screening of Soybean (Glycine Max (L.) Merrill) Genotypes for Resistance to Rust, Yellow Mosaic and Pod Shattering

Applied optic