Constructions, applications and the environment of greenhouses

A greenhouse is essentially an enclosed structure, which traps the short wavelength solar radiation and stores the long wavelength thermal radiation to create a favourable microclimate for higher productivity. The sun’s radiation incident on the greenhouse has two parts: direct radiation and an associated diffuse sky radiation. The diffuse part is not focused by the lenses and goes right through Frensel lenses onto the surface of the absorbers. This energy is absorbed and transformed into heat, which is then transported via the liquid medium in copper pipes to the water (heat) storage tanks or, if used, open fish tanks. In this way, an optimal temperature for both plant cultivation and fish production can be maintained. Stable plant growth conditions are light, temperature and air humidity. Light for the photosynthesis of plants comes from the diffuse radiation, which is without substantial fluctuations and variation throughout most of the day. The air temperature inside the greenhouse is one of thefactors that have an influence on the precocity of production. The selective collector acts in a more perceptible way on extreme air temperatures inside the greenhouse. Hence, the system makes it possible to avoid the excessive deviation of the temperature inside the greenhouse and provides a favourable microclimate for the precocity of the culture. Sediment and some associated water from the sediment traps are used as organic fertiliser for the plant cultivation. The present trend in greenhousecultivation is to extend the crop production season in order to maximise use of the equipment and increase annual productivity and profitability. However, in many Mediterranean greenhouses, such practices are limited because the improper cooling methods (mainly natural or forced  ventilation) used do not provide the desired micro-climatic condition during the summer of a composite climate. Also, some of these greenhouses have been built where the meteorological conditions require some heatingduring the winter, particularly at night. The worst scenario is during the winter months when relatively large difference in temperature between day and night occurs. However, overheating of the greenhouse during the day is common, even in winter, requiring ventilation of the structure. Hence, several techniques have been proposed for the storage of the solar energy received by the greenhouse during the day and its use to heat the structure at night. Reviews of such techniques are presented in thisarticle. Air or water can be used for heat transport. The circulating water is heated during the day via two processes. The water absorbs part of the infrared radiation of the solar spectrum. Since the water is transparent in the visible region, they do not compete with the plants that need it. Alternatively, the water exchanges heat with the greenhouse air through the walls. At night, if the greenhouse temperature goes down below a specified value, the water begins to circulate acting as heat transfersurfaces heating the air in the greenhouse. This article describes various designs of low energy greenhouses. It also, outlines the effect of dense urban building nature on energy consumption, and its contribution to climate change. Measures, which would help to save energy in  greenhouses, are also presented. It also enabled the minimisation of temperature variation and, hence avoided the hazard of any sudden climatic change inside the greenhouse

Regeneration of Sudanese maize inbred lines and open pollinated varieties

Eight maize inbred lines and three open pollinated varieties from Sudan were evaluated for their response to tissue culture. Immature embryos obtained 16 days after pollination were used as explants for callus induction. Calli were induced on LS medium supplemented with 2 mg/L 2,4-dichlorophenoxyacetic acid. Callus induction capacity was highest in inbred lines IL3, IL15 and IL1. The Varieties Hudiba-2 and Hudiba-1 were not statistically different (p >0.05) in callus induction. Thecapacity for embryogenic callus formation was highest in inbred line IL3 followed by IL1 and IL38 and in varieties Hudiba-2 and Hudiba-1. Inbred lines IL16, IL42, IL43 and IL28 had the lowest embryogeniccallus formation capacity. Plant regenerating genotypes were IL3, IL38, IL15, IL1, Hudiba-2 and Mojtamaa-45. Inbred line IL3 was the most regenerable genotype with a shoot formation frequency of 76% averaging 6 shoots per callus. The highest regenerating variety was Mojtamaa-45, which averaged 5 shoots per callus

NOVEL SMART pH SENSITIVE CHITOSAN GRAFTED ALGINATE HYDROGEL MICROCAPSULES FOR ORAL PROTEIN DELIVERY: II. EVALUATION OF THE SWELLING BEHAVIOR

Objective: The main objective of this study is to evaluate the swelling behavior of pH sensitive chitosan (CS) grafted alginate (ALG) hydrogel microcapsules and compared with a simple alginate-chitosan mixed polyelectrolyte complex (PEC) to show the benefits of the used covalently grafting technique. In addition, the behavior of the swelling process under physiological conditions to stimulate gastric, colonic and intestinal medium for grafted PEC microcapsules will be investigated as well.Methods: The new pH sensitive hydrogel microcapsules were prepared using grafting to†technique. Swelling studies were conducted in buffer saline solutions with different pHs using wet beads. In addition; the sensitivity of the grafted microcapsules to the change of pH in the simulated gastric fluid (SGF; pH 1.2), (SIF; pH 6.8) and (SCF; pH 7.4) was investigated.Results: It was observed from the swelling studies that sharp phase transition was recognized between pH 3–4. While this transition became broader and recognized between pH 3.0-7.4, where the maximum value of the equilibrium swelling degree was varied depending on the variation of CS concentration from 0.1% to 0.5%, both grafted and mixed microcapsules exhibit higher swelling degree at high pH 6.8 (120%, 100%) respectively.Conclusion: It was clear from all swelling studies that the grafting technique may be a suitable way for large-scale production of pH sensitive alginate–chitosan microcapsules as a potential system for site-specific oral delivery of protein drugs to different regions of the intestinal tract.Â

NOVEL SMART pH SENSITIVE CHITOSAN GRAFTED ALGINATE HYDROGEL MICROCAPSULES FOR ORAL PROTEIN DELIVERY: I. PREPARATION AND CHARACTERIZATION

Objectives: Preparation and characterization of a new pH sensitive chitosan (CS) grafted alginate (ALG) hydrogel microcapsules for the oral delivery of protein.Methods: The pH sensitive hydrogel microcapsules were prepared for the first time using grafting to†technique. Firstly, alginate was activated using Ï-Benzoquinone (PBQ) as a coupling agent to graft Chitosan chains later on. Both of activated and grafted alginate microcapsules were characterized by Fourier transform-Infra red spectroscopy (FT-IR), thermal gravimetric analysis (TGA) and the morphological structures were investigated using Scanning electron microscopy (SEM) examination.Results: It was found that the optimum conditions affecting the activation process and also the swelling degree of the prepared hydrogel microcapsules were 2% ALG, 0.04M PBQ pH10, 45 °C for 2h. In addition, the grafting process depends on the attached amount of PBQ and CS concentration. Maximum grafting efficiency (GE %) and chitosan add-on percentage were 98.6% and 14.8% respectively using 0.3% CS at 40 °C for 3h.Conclusions: Novel pH sensitive hydrogel microcapsules were prepared via grafting of chitosan molecules on to activated alginate backbone. The formulated microcapsules can be applied as a new pH sensitive carrier for protein drugs. Â

Sudanese Medical Students and Scientific Research

Background: Most of developing countries face problems in assessment of their public health practices. Gain of this knowledge is orchestrated by  research. Medical students can play an essential role in improving public database.Objective: to explore knowledge, attitude and skills of medical students in the Faculty of Medicine and Health Sciences (FMHS), Omdurman Islamic University (OIU) towards research.Materials and Methods: This is a descriptive, analytical, cross-sectional, institution-based study. A total of 442 students, equally from each batch participated in the study. Equal numbers of male andfemale were considered to eliminate gender and seniority bias. Structured pretested questionnaire was used for data collection. Data collected were fed to Statistical Package for Social Sciences(SPSS) version 15. Means, standard deviation and correlations were done where appropriate. Statistical  significance was taken at P =0.05.Results: The mean knowledge score was 37% and attitude was positive in 77.1% of the students. Only 18.3% had attended research methodology workshop. The rate of internet navigation is directly proportional to the social class. Only 14.7% knew the engines used for finding medical literature.Conclusion: The low knowledge score is due to lack of application of research in the academic curriculum; however, the students have a fairly positive attitude. The knowledge is expected to improve with the intended policy to include practical research in the curriculum.Key Words: Public health, academic curriculum, Suda

Burden of visceral leishmaniasis in villages of eastern gedaref state, Sudan: an exhaustive cross-sectional survey.

Since December 2009, Médecins Sans Frontières has diagnosed and treated patients with visceral leishmaniasis (VL) in Tabarak Allah Hospital, eastern Gedaref State, one of the main endemic foci of VL in Sudan. A survey was conducted to estimate the VL incidence in villages around Tabarak Allah

A novel patient-derived intra-femoral xenograft model of bone metastatic prostate cancer that recapitulates mixed osteolytic and osteoblastic lesions

<p>Abstract</p> <p/> <p>Prostate cancer metastasizes to bone in the majority of patients with advanced disease leading to painfully debilitating fractures, spinal compression and rapid decline. In addition, prostate cancer bone metastases often become resistant to standard therapies including androgen deprivation, radiation and chemotherapy. There are currently few models to elucidate mechanisms of interaction between the bone microenvironment and prostate cancer. It is, thus, essential to develop new patient-derived, orthotopic models. Here we report the development and characterization of PCSD1 (Prostate Cancer San Diego 1), a novel patient-derived intra-femoral xenograft model of prostate bone metastatic cancer that recapitulates mixed osteolytic and osteoblastic lesions.</p> <p>Methods</p> <p>A femoral bone metastasis of prostate cancer was removed during hemiarthroplasty and transplanted into <it>Rag2^-/-;γ_c^-/-</it>mice either intra-femorally or sub-cutaneously. Xenograft tumors that developed were analyzed for prostate cancer biomarker expression using RT-PCR and immunohistochemistry. Osteoblastic, osteolytic and mixed lesion formation was measured using micro-computed tomography (microCT).</p> <p>Results</p> <p>PCSD1 cells isolated directly from the patient formed tumors in all mice that were transplanted intra-femorally or sub-cutaneously into <it>Rag2^-/-;γ_c^-/-</it>mice. Xenograft tumors expressed human prostate specific antigen (PSA) in RT-PCR and immunohistochemical analyses. PCSD1 tumors also expressed AR, NKX3.1, Keratins 8 and 18, and AMACR. Histologic and microCT analyses revealed that intra-femoral PCSD1 xenograft tumors formed mixed osteolytic and osteoblastic lesions. PCSD1 tumors have been serially passaged in mice as xenografts intra-femorally or sub-cutaneously as well as grown in culture.</p> <p>Conclusions</p> <p>PCSD1 xenografts tumors were characterized as advanced, luminal epithelial prostate cancer from a bone metastasis using RT-PCR and immunohistochemical biomarker analyses. PCSD1 intra-femoral xenografts formed mixed osteoblastic/osteolytic lesions that closely resembled the bone lesions in the patient. PCSD1 is a new primary prostate cancer bone metastasis-derived xenograft model to study metastatic disease in the bone and to develop novel therapies for inhibiting prostate cancer growth in the bone-niche.</p

Modeling and Simulation of PV Panel Under Different Internal and Environmental Conditions with Non-constant Load

This paper focuses on PV power conversion under different internal and environmental conditions with non-constant load, connected to a smart grid system. Due to environmental conditions, the PV system is a non-linear system and difficult to predict the power conversion. In the aspect of internal variables, it includes the five parameters of the single diode solar cell model identify their sensitivity through error function. It also identifies the relation between environmental conditions, mainly: irradiance, temperature and wind speed. The modeling and computational simulation with laboratory work identify the effects of internal and environmental effect on the system. The model gives details about the sensitivity of each environmental condition using error function. The work includes the decrease of energy conversion by the solar panel as a function of time due to the shadow effect that affects its performance. Besides these, a smart system is introduced as a DAQ system in laboratory environment to get in real time the power conversion value with the P-V and I-V characteristics of the PV panel