Waste cooking oil processing over cobalt aluminate nanoparticles for liquid biofuel hydrocarbons production

The catalytic conversion of waste cooking oil (WCO) was carried out over a synthetic nano catalyst of cobalt aluminate (CoAl₂O₄) to produce biofuel range fractions. A precipitation method was used to create a nanoparticle catalyst, which was then examined using field-emission scanning electron microscopy, X-ray diffraction, energy dispersive X-ray, nitrogen adsorption measurements, high-resolution transmission electron Microscopy (HRTEM), infrared spectroscopy, while a gas chromatography-mass spectrometer (GC-MS) was used to analyze the chemical construction of the liquid biofuel. A range of experimental temperatures was looked at including 350, 375, 400, 425, and 450 °C; hydrogen pressure of 50, 2.5, and 5.0 MPa; and liquid hour space velocity (LHSV) of 1, 2.5, and 5 h^-1. As temperature, pressure, and liquid hourly space velocity increased, the amount of bio-jet and biodiesel fractional products decreased, while liquid light fraction hydrocarbons increased. 93% optimum conversion of waste cooking oil over CoAl₂O₄ nano-particles was achieved at 400 °C, 50 bar, and 1 h^-1 (LHSV) as 20% yield of bio-jet range,16% gasoline, and 53% biodiesel. According to the product analysis, catalytic hydrocracking of WCO resulted in fuels with chemical and physical characteristics that were on par with those required for fuels derived from petroleum. The study's findings demonstrated the nano cobalt aluminate catalyst's high performance in a catalytic cracking process, which resulted in a WCO to biofuel conversion ratio that was greater than 90%. In this study, we looked at cobalt aluminate nanoparticles as a less complex and expensive alternative to traditional zeolite catalysts for the catalytic cracking process used to produce biofuel and thus can be manufactured locally, which saves the cost of imports for us as a developing country.

Mpox in Nigeria: Perceptions and knowledge of the disease among critical stakeholders-Global public health consequences

BACKGROUND

The mpox (monkeypox) disease is a re-emerging viral zoonosis of international concern that is endemic in parts of Africa. The mpox virus (MPXV), which was hitherto largely limited to some Central and West African countries, was declared a public health emergency of international concern by the WHO on July 23, 2022 following the rapid spread of the virus to non-endemic countries. Globally, as of March 16, 2023, the WHO had reported 86,496 laboratory-confirmed cases of mpox and 111 deaths in 110 countries. Of the 1,420 cases of mpox reported in Africa as of March 16, 2023, Nigeria alone recorded 57.1% (812) of the confirmed cases and eight fatalities recorded in the continent. To help improve on the understanding of the current situation in Nigeria, the present study assessed the perception and knowledge of mpox among Nigerian healthcare workers, academics and tertiary students. The study also sought to highlight the global public health significance of the MPXV, and recommend a One Health approach to limit exporting of the virus beyond the borders of Nigeria.

METHODS

A web-based cross-sectional survey was conducted between 24 July 2022 and 12 August 2022 to evaluate the perception and knowledge of mpox among 1544 Nigerians, consisted of healthcare workers (n = 832), academics (n = 306) and tertiary students (n = 462). Data on the respondents' socio demographics and their information sources on mpox were also collected. Each correct response was allotted one point while an incorrect response was scored zero. The scores for perception and knowledge were dichotomized into positive (>5.5) and negative (≤5.5) and adequate (>5.8) and inadequate (≤5.8), respectively; using the average scores for perception and knowledge. The average score for perception and knowledge were summarised and presented as the mean and standard deviation (SD). Chi-square tests of association and binary logistic regression were carried out to determine factors associated with the outcome variables.

RESULTS

Of the 1452 respondents that had heard of mpox, 878 (60.5%) and 419 (28.9%) had adequate knowledge and positive perception concerning MPXV infection respectively. Average perception score was 5.5. Mean perception and knowledge scores were 4.5(SD: 2.0) and 5.8 (SD: 1.9), respectively. Factors that were significantly associated with knowledge level were age (p = 0.020) educational qualification attained (p = 0.004), occupation (p<0.001), and geopolitical zone of residency (p = 0.001). There was a positive correlation between perception and knowledge scores (r = 0.4, p<0.001). Positive perceptions were likely among respondents who had tertiary education, and residing in North-west Nigeria. Likewise, adequate knowledge scores were likely among respondents under 30 years of age, with tertiary education or reside in North-west Nigeria. Sources of information were significantly associated with perception (p = 0.004) and knowledge (p<0.001) of the respondents.

CONCLUSION

The findings of this study show that there is disparity in the knowledge and perception of mpox in the study population, and as a result, there is a need to intensify awareness about MPXV infection to enhance positive perception among the respondents. This has potential to safeguard public health and contain the disease thus preventing it from spreading to the global community. A One Health approach involving animal and human health workers is imperative for improved knowledge and a good perception towards the disease among respondents, and enhanced active surveillance and early detection of MPXV in reservoir hosts (rodents and non-human primates); to prevent reverse zoonotic transmission of the virus at the human-animal interface.

COVID-19 Vaccine Hesitancy and Determinants of Acceptance among Healthcare Workers, Academics and Tertiary Students in Nigeria

The COVID-19 pandemic has resulted in millions of human deaths, prompting the rapid development and regulatory approval of several vaccines. Although Nigeria implemented a COVID-19 vaccination program on 15 March 2021, low vaccine acceptance remains a major challenge. To provide insight on factors associated with COVID-19 vaccine hesitancy (VH), we conducted a national survey among healthcare workers, academics, and tertiary students, between 1 September 2021 and 31 December 2021. We fitted a logistic regression model to the data and examined factors associated with VH to support targeted health awareness campaigns to address public concerns and improve vaccination rates on par with global efforts. A total of 1525 respondents took part in the survey, composed of healthcare-workers (24.5%, 373/1525), academics (26.9%, 410/1525), and students (48.7%, 742/1525). Only 29% (446/1525) of the respondents were vaccinated at the time of this study. Of the 446 vaccinated respondents, 35.7% (159/446), 61.4% (274/446) and 2.9% (13/446) had one, two and three or more doses, respectively. Reasons for VH included: difficulty in the vaccination request/registration protocols (21.3%, 633/1079); bad feelings towards the vaccines due to negative social media reports/rumours (21.3%, 633/1079); personal ideology/religious beliefs against vaccination (16.7%, 495/1079); and poor confidence that preventive measures were enough to protect against COVID-19 (11%, 323/1079). Some health concerns that deterred unvaccinated respondents were: innate immunity issues (27.7%, 345/1079); allergic reaction concerns (24.6%, 307/1079); and blood clot problems in women (21.4%, 266/1079). In the multivariable model, location of respondents/geopolitical zones, level of education, testing for COVID-19, occupation/job description and religion were significantly associated with VH. Findings from this study underscore the need for targeted awareness creation to increase COVID-19 vaccination coverage in Nigeria and elsewhere. Besides professionals, similar studies are recommended in the general population to develop appropriate public health interventions to improve COVID-19 vaccine uptake.

Linum usitatissimum seeds oil down-regulates mRNA expression for the steroidogenic acute regulatory protein and Cyp11A1 genes, ameliorating letrezole-induced polycystic ovarian syndrome in a rat model

The safety and effectiveness of nutricetics suggest that they may offer an alternative to pharmaceutical and surgical therapy for hormone-dependent disorders, such as polycystic ovarian syndrome (PCOS). We investigated the effects of Linum usitatissimum seed oil (LSO) on ovarian functionality, its molecular targets, and the oxidative response in hyperandrogenism-induced polycystic ovary. The composition of LSO has been analyzed using ultra-performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC-ESI-MS). A well-established PCOS rat model orally administered with letrozole daily for 21 days was used to investigate the effect of LSO at doses of 1 and 2 mL/kg body weight for 28 days. The effect on hormonal profile and antioxidant status, histopathology (cell proliferation), and the expression ratio of the steroidogenic acute regulatory protein (StAR) and Cyp11A1 gene were evaluated. LSO exerted beneficial effects on PCOS rat models via restoring glutathione (GSH), malondialdehyde (MDA), beta subunit subunit luteinizing hormone (LH), testosterone levels, and histopathological scoring. Furthermore, LSO reversed the elevated StAR and Cyp11A1 genes in the PCOS rat model. This study demonstrated the molecular and cellular mechanisms of the beneficial effect of LSO against the reproductive and metabolic disorders of PCOS.

Sildenafil ameliorates Alzheimer disease via the modulation of vascular endothelial growth factor and vascular cell adhesion molecule-1 in rats

Alzheimer disease (AD) is a chronic neurodegenerative disease with multi-pathways pathogenesis. Sildenafil is a selective phosphodiesterase-5 inhibitor with a potential benefit in the treatment of AD. This study investigated the possible mechanisms underlying the effect of sildenafil in AD with emphasis on vascular endothelial growth factor (VEGF), and vascular cell adhesion molecule-1 (VCAM-1). Twenty-four adult male rats were classified into four groups; control group: received vehicles, sildenafil-control: received sildenafil (15 mg/kg/day, p.o.), AD group received Aluminum (25 mg/kg/day, p.o.), AD-treated group: received sildenafil (15 mg/kg/day, p.o.) for 6 weeks. AD was assessed by memory performance test and confirmed by histopathological examination and immunostaining of, neurogenesis marker nestin and α-synuclein. The levels of VEGF-A, VCAM-1, oxidative stress markers and TNF-α in brain tissue were evaluated. AD rats showed histopathological evidences of AD; along with increased latency time in the memory test. There was a decrease in VEGF-A, and an increase in VCAM-1, TNF-α, and oxidative stress markers. Immunohistochemical study showed a significant increase in α-synuclein and a significant decrease in nestin expressions in brain tissues. Sildenafil administration ameliorated the histopathological changes and decreased latency time. Such effect was associated with a decrease in VCAM-1, TNF-α and oxidative stress as well as an increase in VEGF-A. Sildenafil caused a significant increase in nestin and a decrease in α-synuclein immunostaining. These findings suggested a protective effect of sildenafil via modulation of VEGF-A, and VCAM-1.

Light transmission and internal scattering in pulsed laser-etched partially-transparent silicon wafers

Continuing trend in silicon wafer thickness directed at cost reduction approaches basic boundaries created by: (a) mismatch between Al paste and Si wafer thermal expansion and (b) incomplete optical absorption. With its symmetrical front and back electrical contacts, the bifacial solar cell setup reduces stress due to mismatch thermal expansion, decreases metal use and increases high temperature efficiency. Efficiency improvement is accomplished in bifacial solar cells by capturing light from the back surface. Partially transparent wafers provide an option to improve near-infrared radiation absorption within Si wafer. To fully absorb optical radiation, three-dimensional texture of these kinds of wafers is essential. Pulsed laser interactions, thermal oxidation, and wet chemical etching are included in this research. A feature of its energy and pattern setup is the interaction of pulsed laser with Si, running at 1.064 μm wavelength and micro-second length. Two experimental settings were explored: (a) post-laser chemical etching with potassium hydro-oxide etching with thermal oxide as etching mask and (b) post-laser heat Si surface oxidation. Due to fast melting and recrystallization, laser pulsed processing inherently produces its own texture. Some of these spherically-shaped, randomly focused characteristics improve inner scattering and boost near-infrared absorption within the wafer. These characteristics are separated during chemical etching with the thermally-grown oxide layer as an etch mask. Comparison of optical absorption in both surfaces shows almost a rise in the magnitude of absorption in non-etched surfaces. Detailed optical (optical microscope and IR absorption), morphological (field emission scanning electron microscope) and heat imaging (far IR camera) analyses were performed to comprehend physical processes that contribute to near-IR absorption improvement. Such kinds of partially-transparent, three-dimensional textured Si wafers are anticipated to discover applications for bifacial solar cells as substrates.

Fabrication of Stannate Perovskite Structure as Optoelectronics Material: An Overview

This paper presents a review of recent fabrication progress of perovskite-type material suited for the future optoelectronics applications. Wide varieties of optoelectronic devices include solar cell, liquid displays, transparent FETs, etc are becoming the mainstream for the future electronics global industry. In June 2015, the major breakthrough of perovskite structure in solar energy harvesting with PCE of 20.1% has achieved. Since then, numerous research has been conducted progressively to further enhance the performance of the perovskite structure as new alternative materials for optoelectronics applications. The perovskite-type oxide is having typical ABO3 crystallized structure. It is one of an important class of materials that have many exceptional physical properties such as superconductivity, colossal magnetoresistance, ferromagnetic, piezoelectric, high-transition-temperature superconductivity, ferroelectricity, piezoelectricity, and photoelectrochemical sensitivity. In this paper, we reviewed development progress one of the major classes of perovskite-type materials namely Stannate-based. Calculated data from simulation results such as DFT and first principle were excluded and only fabricated devices are covered in this paper.

PI3K/Akt and Nrf2/HO-1 pathways involved in the hepatoprotective effect of verapamil against thioacetamide toxicity in rats

Liver is a precious organ to maintain body life. Hepatotoxicity is a worldwide health problem that is still a challenge for research. Although countless pharmaceutical drugs and herbal compounds were screened for their hepatoprotective effects, the death from hepatotoxicity is increasing. Thus, there is continuous necessity of searching for the hepatoprotective effect of commonly used drugs. Accordingly, our aim was to examine a hepatoprotective potential for the antihypertensive drug, verapamil, and searching for new insights underlie its protective mechanism. Four groups of adult male rats were randomly arranged as controls, thioacetamide (TAA) hepatotoxic, and TAA + verapamil treated. Serum liver enzyme, hepatic antioxidant, lipid peroxidation, and inflammatory parameters were assessed. Gene relative expression for heme oxygenase-1 (HO-1), nuclear factor-erythroid 2-related factor 2 (Nrf2), phosphoinositide 3-kinase (PI3K), and serine/threonine-specific protein kinase (Akt) were quantified in hepatic tissue. TAA caused hepatic injury evident both histopathologically and biochemically by a decrease in all gene expressions. Verapamil alleviated the injury via its antioxidant and anti-inflammatory effects that were suggested to be via upregulation of the previous gene expressions. In conclusion, the calcium channel blocker, verapamil, that is used widely as antihypertensive exhibits a valuable hepatoprotective effect. The protection partially rests on activation of Nrf2/HO-1 and PI3K/Akt pathways.

Protective effects of selenium and nano-selenium on bisphenol-induced reproductive toxicity in male rats

Bisphenol A (BPA) is a widespread compound associated with the manufacture of many consumer products. The BPA-induced reproductive toxicity was reported to be mainly attributed to oxidative stress. However, the role of antioxidants usage to decrease the injurious effects of BPA, on male reproductive functions, remains to unveil. The present research is established to evaluate the role of selenium (Se) and its nano form (NSe) as protective agents to alleviate BPA-induced testicular toxicity. Ninety mature albino male rats were assigned into six equal groups: negative control; orally BPA 150 mg/kg; Se 3 mg/kg; NSe 2 mg/kg; both BPA 150 mg/kg and Se 3 mg/kg; and BPA 150 mg/kg + NSe 2 mg/kg. The experiment lasted for 70 consecutive days, and then serum was collected for estimation of prostatic acid phosphatase. Testicular tissues were subjected to measurement of antioxidant status, lipid peroxidation, DNA damage, and expression of some apoptotic genes. Our results reported that BPA-induced marked testicular damage evidenced by significant elevations in serum prostatic acid phosphatase activity, malondialdehyde levels, a decrease in testicular catalase activity and reduced glutathione level. Moreover, marked DNA internucleosomal fragmentation pattern as well as upregulation of cyclooxygenase-2 and estrogen receptor-2 NSe genes were detected. Coadministration of Se and NSe attenuated the reproductive toxicity induced by BPA via improvement of the antioxidant activity, genetic changes, and restoration of testicular tissue nearly as control one. These results indicated that both Se and NSe forms could be used as reproductive protective agents against the detrimental effect induced by BPA. However, the NSe surpassed the selenium in modulating the DNA laddering, and the studied gene expression levels, and offered a potent reproductive protection.

The potential protective effect of α-lipoic acid against nanocopper particle-induced hepatotoxicity in male rats

The present research task is aimed to evaluate the role of exogenous α-lipoic acid (ALA) (100 mg/kg body weight) as hepatoprotective and potent antioxidant in amelioration of copper nanoparticle (CNP)-induced hepatotoxicity. Forty male rats were randomly assigned into four equal groups: group I (control), group II received CNPs, group III received CNPs + ALA, and finally group IV received ALA for 2 months. At the end of the experimental period, the rats were decapitated, and blood and liver tissue samples were collected for measurement of liver function tests, antioxidant status, lipid peroxidation (LPO), copper content, expression of some apoptotic genes, and histopathological analysis. CNPs induced marked hepatic damages as evident by severe alteration in hepatic biomarkers. This was accompanied by a significant elevation in hepatic LPO and induced nitric oxide, copper content, and expression level of apoptotic genes (C-myc and C-jun). In contrast, marked depletion for antioxidant parameters was detected. These findings were confirmed with severe pathological alterations. Coadministration of ALA as a powerful antioxidant attenuates the hepatotoxic effects of CNPs through improvement of liver parameters, oxidative status, genetic changes, and preservation of liver integrity through histopathological analysis. These results suggest that consumed ALA could be used as an applicable hepatoprotective agent against oxidative damage mediated by nanoparticles intoxication.

Alteration of redox status by commonly used antimalarial drugs in the north-western region of Nigeria

This study was designed to investigate the alteration of redox status by commonly used antimalarials in Nigeria. Drugs used were artemisinin, artesunate, chloroquine, coartem and quinine at the final concentrations of 0.5–8.0 mg/mL. Blood samples were collected from malarial patients and apparently healthy humans for comparison. Reduced glutathione, catalase, superoxide dismutase (SOD) activities, protein content and lipid peroxidation were determined. All drugs significantly ( p < 0.05) increases the protein level relative to control in normal blood, whereas in the infected, a significant ( p < 0.05) reduction was observed. In normal blood, the antimalarials dose dependently decreased ( p < 0.05) SOD and catalase activities with significant ( p < 0.05) increase in the infected. The level of glutathione in normal blood significantly ( p < 0.05) increases as compared with control, whereas in the infected, similar observation was made except that the levels were less, relative to control sample. Malondialdehyde level significantly ( p < 0.05) increases with increase in drugs concentration even though less than the level in the control with few exceptions. These effects were dose dependent and more pronounced in non-malarial conditions. Commonly used antimalarials might alter the redox status in both healthy and non-healthy subjects thereby inducing oxidative stress.

MH17: the Malaysian experience

A disaster is a natural or man-made (or technological) hazard resulting in an event of substantial extent causing significant physical damage or destruction, loss of life, or drastic change to the environment. It is a phenomenon that can cause damage to life and property and destroy the economic, social and cultural life of the people; and overwhelms the capacity of the community to cope with the event. The recent tragic aviation accidents in 2014 involving Malaysia Airlines flights MH370 and MH17 shocked the world in an unprecedented manner. This paper focuses on the Malaysian experience in the MH17 mission in Ukraine as well as the first ever international Disaster Victim Identification (DVI) operation for the Malaysian DVI team. The DVI operations in Hilversum, the Netherlands were well described in stages. The Netherlands' Landelijk Team Forensische Opsporing as the lead DVI team in Hilversum operated systematically, ensuring the success of the whole mission. This paper discusses the lessons learned by the Malaysian team on proper DVI structure, inter- and intra-agency cooperation, facilities planning and set up, logistics and health and safety aspects, as well as effective communication and collaboration with other international delegates. Several issues and challenges faced by the Malaysian team were also documented. In addition, the authors shared views, opinions and recommendations for a more comprehensive DVI operation in the future.

Association of retinal vessel calibre and visual outcome in eyes with diabetic macular oedema treated with ranibizumab

PURPOSE

The study aims to identify the association between the baseline retinal vascular calibre and visual outcome of patients with diabetic macular oedema (DMO) treated with intravitreal ranibizumab.

METHODS

The 1-M field (as defined in the ETDRS study) of the digital colour fundus photographs of DMO patients who had been treated primarily with ranibizumab in a clinical trial was assessed. Of the 84 patients, 25 had gradable retinal photographs that could be subjected to analyses by the Interactive Vessel Analysis (IVAN) software at baseline. The average retinal vascular calibre of the six largest venules (CRVE) and the six largest arterioles (CRAE) in the peripapillary area (0.5 and 1 disc diameter from the optic disc margin) was measured. The relationship between CRVE and CRAE at baseline and the change in visual acuity at month 12 was assessed using the Mann-Whitney U test.

RESULTS

Ten eyes from 10 patients who had shown an improvement of ≥2 lines of best corrected visual acuity (BCVA) at month 12 had a wider baseline CRVE (248.3±24.5 μm) compared with the 15 eyes from 15 patients who did not show the improvement of ≥2 lines (226.6±44.8 μm, P<0.05). The baseline CRAE did not differ significantly in these patients (156.1±22.7 vs 142±17.5 μm, P=0.17).

CONCLUSIONS

A wider baseline retinal venular calibre may be a predictor of better visual outcome in DMO eyes treated with ranibizumab. Further prospective studies with a larger sample size and a broader range of disease severity and visual acuity are needed to confirm this finding.

Trypanosoma brucei brucei infected rats: micronucleated polychromatic erythrocytes

The emergence of bone marrow micronucleated polychromatic erythrocytes (MN-PCE) in rats experimentally infected with Trypanosoma brucei brucei was examined in order to understand the bone marrow effects in trypanosomiasis infection. Bone marrow was collected for micronucleus assay while blood samples were collected from infected rat for hematological analysis. The results showed evidence of MN-PCE at 12.75 ± 0.65 micronuclei/ 1000 PCE and 9.60 ± 2.95 micronuclei/1000 PCE for rats infected for 21 days and 14 days respectively. The hematology examination revealed changes in packed cell volume, haemoglobin and red blood cells with concomitant increase in parasitemia. This study revealed that the generation of MN-PCE was induced by an acute infection of T. b. brucei in rats and this highlights an important phase in the pathogenesis of the disease that may indicate possible damage to genetic information.

Induction of resistance in tomato plants against tomato mosaic tobamovirus using beneficial microbial isolates

The possibility of making use of the phenome non of Systemic Acquired Resistance (SAR) to control viruses achieved by the soaking treatment of tomato seeds cv. Castl Rock with three growth forms to Bacillus circulans, Pseudomonas fluorescens 2 and Trichoderma harzianum against Tomato mosaic tobamovirus (ToMV) infection. All the application forms of beneficial biotic inducers were reduced the mean number of ToMV local lesions on Datura metel. P. fluorescens 2 was found to be the best treatment in three forms on reduction of local lesion number 42.2, 32.7 and 38.1 of microbial liquid culture, microbial cells or spores and microbial culture filtrate forms, respectively, while the highest mean numbers of local lesions were 51.5, 61.7 and 73.5 of microbial liquid culture, microbial cells or spores and microbial culture filtrate, respectively for T. harzianum. The microbial culture filtrate form was more effective than other microbial forms to reduce mean number of ToMV local lesions to B. circulans, P. fluorescens 2 and T. harzianum isolates, 40.7, 32.1 and 51.5, respectively. The individual microbial isolates on all three microbial forms able to vary ToMV local lesions similarity (homologous or heterologous) and morphology (size center and surrounded with halo or without halo) compared with TMV mother strain.

Binary and ternary copper(II) complexes of a tridentate ONS ligand derived from 2-aminochromone-3 carboxaldehyde and thiosemicarbazide: synthesis, spectral studies and antimicrobial activity

A tridentate ONS donor ligand, HL, was synthesized by the condensation of 2-aminochromone-3-carboxaldehyde with thiosemicarbazide. The structure of the ligand was elucidated by elemental analyses, IR, (1)H and (13)C NMR, electronic and mass spectra. Reaction of the ligand with several copper(II) salts, including AcO(-), NO3(-), SO4(2-), Cl(-), Br(-) and ClO4(-) afforded different metal complexes that reflect the non-coordinating or weakly coordinating power of the ClO4(-) and Br(-) anions as compared to the strongly coordinating power of AcO(-), SO4(2-), Cl(-) and NO3(-) anions. Also, the ligand was allowed to react with Cu(II) ion in the presence of a secondary ligand (L') [N,O-donor; 8-hydroxyquinoline or N,N-donor; 1,10-phenanthroline]. Characterization and structure elucidation of the prepared complexes were achieved by elemental and thermal analyses, IR, electronic, mass and EPR spectra as well as conductivity and magnetic susceptibility measurements. The EPR spin Hamiltonian parameters of some complexes were calculated. The metal complexes exhibited octahedral and square planar geometrical arrangements depending on the nature of the anion. The ligand and most of its metal complexes showed antibacterial activity towards Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis), Gram-negative bacteria (Salmonella typhimurium and Escherichia coli), yeast (Candida albicans) and fungus (Aspergillus fumigatus).

Compliance with the guidelines of prescription writing in a central hospital in the West Bank

This retrospective, cross-sectional study was carried out to evaluate the quality of 2208 outpatient prescriptions in a central hospital in the West Bank, Palestine. The physicians' handwriting was poorly readable or illegible in one-third of the prescriptions. The prescriber's name and signature and patient's name were mentioned in almost all orders whereas the patient's age was stated in 54.9%. The vast majority of physicians (95.5%) prescribed drugs using their trade (brand) names. Drug strength, quantity and dose/frequency were stated in 61.1%, 76% and 73.8% of prescriptions respectively. Only 33 prescriptions (1.5%) contained full directions for use for all drugs. Correlation analysis revealed that the presence of certain prescription elements was statistically significantly associated with the clinic of origin and the number of drugs prescribed. The overall poor legibility and incompleteness of the prescriptions is of concern.

In vitro anti-oxidative activities of the various parts of Parkia biglobosa and GC-MS analysis of extracts with high activity

The anti-oxidative activities of sequentially extracted solvent fractions of different parts of P. biglobosa were evaluated in a series of in vitro assays. Our findings indicated that all extracts had electron donating and free radical scavenging activities. But the ethanol (EtOH) extracts from all the parts demonstrated more promising anti-oxidative effects in these experimental models. Apart from the aqueous extracts of the stem bark and leaves, all other extracts exhibited hydroxyl radical scavenging (HRS) activity but the ethyl acetate (EtOAc) extract of the stem bark and EtOH extracts of the root and leaves possessed more powerful HRS activity than other corresponding extracts in the parts. Further, nitric oxide (NO) inhibition activities were observed in all the extracts except the EtOAc extract of the stem bark which showed pro-oxidative activity. However, the EtOH extract of the stem bark and root as well as the EtOAc extract of the leaves displayed more potent anti-NO activity than other extracts in the parts. The GC-MS analysis of the EtOH extracts revealed that the most abundant phytochemicals are pyrogallol derivatives. Data from this study suggest that the EtOH extracts from different parts of P. biglobosa contained potent anti-oxidative agents and pyrogallol could be the main bioactive constituent.

Histological pattern of primary glomerular diseases among adult Sudanese patients: A single center experience

In Sudan, like most developing countries, the incidence and histologic patterns of primary glomerulonephritis (GN) remains undetermined. A cross-sectional hospital-based prospective study was performed to determine the pattern of primary GN among adult Sudanese patients. The study was conducted at Khartoum Teaching Hospital from September 2010 to August 2011. It included all adult patients with suspected primary glomerular disease and who underwent native kidney biopsy. A total of 83 adult patients were biopsied with 71 patients (85.5%) being diagnosed as having primary GN. Among those with primary GN the mean age was 34.6 ± 18 years and males represent 54.9%. In 46.5% kidney biopsy was indicated by the presence of nephrotic syndrome, whereas in 33.8% biopsies were performed due to unexplained elevations in renal parameters. Primary focal segmental glomerulosclerosis (FSGS) was diagnosed in 29.6% of patients, followed by membrano-proliferative glomerulonephritis (MPGN) in 26.8% and minimal change disease in 16.9%. IgA nephropathy was observed in 5.6%. Complications following kidney biopsies were reported in 9.6% of biopsied patients. Nephrotic syndrome in an adult was the most common indication for kidney biopsy in our unit. A large number of patients were biopsied due to elevated renal parameters, which reflected the increasing awareness toward thoroughly diagnosing patients with suspected reversible kidney damage. In conclusion, FSGS and MPGN make the most common causes of primary GN among Sudanese adults. Creation of a national renal registry is essential for obtaining more specified epidemiological data.

Effect of activated vitamin D on glucoparameters in HCV seropositive and seronegative patients on chronic hemodialysis

INTRODUCTION

Many studies support the role of vitamin D in the pathogenesis of both types of diabetes. Pancreatic tissues express the vitamin D receptor (VDR) and vitamin D-binding protein; some allelic variations in genes involved in vitamin D metabolism and VDR are associated with glucose intolerance, defective insulin secretion, and sensitivity. Epidemiological links have been established between type 2 diabetes mellitus (DM) and hepatitis C virus (HCV) infection.

AIM

To explore the possible therapeutic potential of pharmacologic doses of 1-α-hydroxy vitamin D therapy in improving pancreatic β-cell function in HCV seropositive hemodialysis (HD) patients.

PATIENTS AND METHODS

Twenty HCV seropositive HD patients and 20 HCV seronegative patients as control group were randomly selected from HD units. 1-α-Hydroxy vitamin D therapy was administrated in the dose ranged from 0.25 to 0.5 μg/day for 3 months. Corrected total serum calcium, phosphorus, intact parathyroid hormone (iPTH), 25-hydroxy vitamin D [25(OH) vitamin D], 1,25-dihydroxy vitamin D, and glucoparameters [fasting blood glucose, glycohemoglobin test (HbA1c%), homeostatic model assessment (HOMA)-insulin resistance, and HOMA-β-cell function% (B%)] were measured under basal conditions and after 3 months of therapy.

RESULTS

There was highly significant improvement in the concentrations of fetal bovine serum (FBS), serum insulin, HbA1c%, 25(OH) vitamin D, and HOMA-β-cell function in HCV seropositive and HCV seronegative groups after oral 1-alphacalcidiol therapy (p < 0.001). Positive correlation exists between the percentage increase in serum insulin and that in HOMA-β-cell function versus 25(OH) vitamin D (p < 0.021 and p < 0.027, respectively) in HCV negative group.

CONCLUSION

1-α-Hydroxy vitamin D oral therapy may improve glycemic control in HCV seropositive and HCV seronegative HD patients.

Effects of vitamin E administration on Plasmodium berghei induced pathological changes and oxidative stress in mice

The effects of daily intraperitoneal doses of 1000 i.u/kg body weight of vitamin E on the course of Plasmodium berghei NK 65 infection and the parasite-induced anemia as well as alterations in the relative weight of some selected organs and antioxidant status in mice were investigated. The number of parasitized red cells were not initially affected by the vitamin administration but were persistently lowered after 11th day post infection to the termination of the experiment. The P. berghei infection was found to induce anemia, significantly (P<0.05) increased the relative weight of liver, spleen and kidney but significantly decreased (P<0.05) the relative brain weight. However, all the parasite-induced changes in these parameters were significantly (P<0.05) ameliorated by the vitamin administration. Furthermore, malonydialdehyde concentration in the serum, liver and brain of infected animals was significantly (P<0.05) increased whereas superoxide dismutase and catalase activities were significantly (P<0.05) decreased by the infection. But vitamin E administration was found to, a significant degree (P<0.05), reversed the disease-induced alterations in these oxidative stress markers. It was concluded that vitamin E at the dose and route used prevented P. berghei induced anemia as well as alterations in relative organ weight and antioxidant status in mice.

Senna occidentalis leaf extract possesses antitrypanosomal activity and ameliorates the trypanosome-induced anemia and organ damage

The in vitro and in vivo antitrypanosomal effects of the ethanol extract of Senna occidentalis leaf were investigated. The crude extract exhibited an in vitro activity against Trypanosoma brucei brucei as it completely eliminated parasites’ motility within 10 minutes postincubation with 6.66 mg/ml of effective extract concentration. The extract was further used to treat experimentally T. brucei brucei infected rats at concentrations of 100 and 200 mg/kg body weight, beginning on day 5 post infections (p.i.). At the termination of the experiment on Day 11 p.i., the extract significantly (P < 0.05) kept the parasitemia lower than was recorded in the infected untreated rats. All the infected animals developed anemia, the severity of which was significantly (P < 0.05) ameliorated by the extract treatment. The infection caused significant (P < 0.05) increases in serum alanine and aspartate aminotransferases as well as serum urea and creatinine levels. However, treatment of infected animals with the extract significantly (P < 0.05) prevented the trypanosome-induced increase in these biochemical indices. Furthermore, the T. brucei infection caused hepatomegaly and splenomegaly that were significantly (P < 0.05) ameliorated by the extract administration. It was concluded that orally administered ethanol extract of S. occidentalis leaf possessed anti-T. brucei brucei activity and could ameliorate the disease-induced anemia and organ damage.

Inhibition of Naja nigricolis (Reinhardt) venom protease activity by Luffa egyptiaca (Mill) and Nicotiana rustica (Linn) extracts

Luffa egyptiaca and Nicotiana rustica are used in traditional medicine to treat snakebites and were evaluated for inhibitory activities on Naja nigricolis venom protease. The aqueous and ethanolic extracts of L. egyptiaca significantly reduced the maximum velocity (Vmax) and the computed index of physiological efficiency (Kcat) of the enzyme in a dose dependent fashion. The protease activity was non-competitively inhibited by the aqueous extract of N. rustica with the Vmax significantly decreased and the K(M) remained unchanged. However, the N. rustica ethanol extract completely inhibited the protease activity. Ethyl acetate fractions partitioned from ethanol extracts of both plants were also found to completely inhibit the N. nigricolis venom protease activity at 0.1 and 0.05%. The use of these plants could be important in the treatment of snakebites.

Indices of kidney damage and cardiovascular disease risk factors in a semiurban community of iloye, South-west Nigeria

Health screening exercises are important, as they enable early detection of diseases in individual subjects and also enable data collection, useful in estimating disease burden in the community. This paper describes the findings of a health screening exercise conducted in a semiurban population of Iloye, by the Rotary Club of Ota, Ogun State, Western Nigeria, as a part of its community-oriented services and projects. Three hundred and twenty six community members were screened during the exercise. There were 189 (57.97%) females and 137 (42.03%) males, with a mean age of 43.5 ± 14.88 yrs. Urinary abnormality and/or creatinine clearance less than 90 mls/min was detected in 147 (45.09%) participants. 99 (30.37%) participants had proteinuria, 16 (4.91%) had haematuria, and 5 (1.53%) participants had both haematuria and proteinuria. Eight (2.45%) participants had GFR less than 60 mls/min. Elevated blood pressure was found in 152 (46.63%), while 3 (0.9%) participants had diabetes, 71 (21.8%) were obese, 16 (4.9%) had hypercholesterolaemia, and 3 (0.9%) had hypertriglyceridaemia. Prevalence of both smoking and alcohol consumption was 6 (1.84%). It was concluded that the prevalence of indices of kidney damage and cardiovascular risk factors is high in Iloye community.

Environmental exposure to endotoxin in rural and urban Egyptian school children and its relation to asthma and atopy

AIM

The environmental exposure of farm children to micro-organisms in dust has been related to a reduced prevalence of asthma and atopy. The aim of this study was to evaluate the relation between settled dust endotoxin and development of asthma and/or atopy in rural and urban school children.

METHODS

A comparative study was conducted on 40 rural and 40 urban school children (6-12 years). Parental self-reported allergic symptoms questionnaires were distributed. Forced expiratory volume in the first second (FEV1), forced vital capacity (FVC) were measured using MIR spirobank and FVE1% was calculated. Skin prick testing with the most common aeroallergens was performed. Limulus amebocyte lysate endotoxin content was measured in settled dust samples.

RESULTS

The rural group which has higher exposure to farm animals and feeding on farm milk has less allergic symptoms. Rural students showed highly significant FEV1, FEV1% and significant FVC versus urban students (110.9±19.7, 103.8±12.2, 105.8±24.3 vs. 92.3±24.2, 98.4±18.9, 92.7±23.2, respectively). Rural school dust contains significantly higher level of endotoxin (2-3 EU/mg) than urban school (0-0.1 EU/mg). Urban residence was associated with increase risk of asthma after age and sex adjustments ([ORadj], 5.16; 95% [CI], 0.95-28).

CONCLUSION

Our results support the hygiene theory, i.e., endotoxin exposure could be protective to asthma and atopy in school children.

Confirmatory studies on the antioxidant and antidiabetic effect of quercetin in rats

Quercetin (QE), one of natural flavanoid group, was widely distributed as a secondary metabolite in plant kingdom. It has been believed that oxidative stress plays a role in the pathogenesis of diabetes mellitus (DM). The aim of the present study was the evaluation of possible effects of QE on blood glucose and antioxidant enzymes in experimental streptozotocin (STZ)-induced diabetes in rats. STZ was injected intraperitoneally with single dose of 50 mg/kg for diabetes induction. QE (15 mg/kg bw day, intraperitoneal (i.p.) injection) was injected for 3 days prior to STZ administration; these injections were continued to the end of the study (for 25 days). Glucose tolerance test and random plasma glucose were done for all animals. Cellular antioxidant enzymes such as glutathione peroxidase (GSHPx), superoxide dismutase (SOD) and catalase (CAT) activities were measured in pancreatic homogenates. Quercetin had no effect on plasma glucose level of normal animals but its pre- treatment was able to prevent diabetes induced by single intraperitoneal injection of streptozocintreated rats. Antioxidant enzyme activity significantly decreased in STZ induced diabetic group. QE treatment significantly increased the antioxidant enzyme activities. It could be concluded that quercetin, a flavonoid with antioxidant properties, exerting its beneficial antidiabetic effects.

The hypoglycaemic activity of the aqueous extract of Stachytarpheta angustifolia (Verbanaceae) in normoglycaemic and alloxan-induced diabetic rats

The hypoglycaemic activity of the aqueous extract of Stachytarpheta angustifolia (Verbanaceae) was studied in normoglycaemic and alloxan-induced diabetic rats. The extract was administered orally to the rats and blood glucose level was monitored for 7 h. Results indicate that the aqueous extract (750 mg kg(-1)) produced a significant blood glucose reduction in both normoglycaemic and alloxan-induced diabetic rats (p < 0.05). The present result therefore appears to support the use of the plant aqueous extract for the management of type 2 diabetes by traditional medical practitioners in Northern Nigeria. The mechanism of action of the aqueous extract needs to be studied.

The influence of different nutrient levels on insect-induced plant volatiles in Bt and conventional oilseed rape plants

Transgenic Bt (expressing the cry1Ac endotoxin gene) and conventional oilseed rape plants grown in different soils were used to study nutrient uptake and emission of volatiles after herbivore damage. All plants were greenhouse-grown in soils representing low-, medium- and high-nutrient levels. The concentrations of N, P, K, Mg and Zn were significantly affected by the transgene, while the main effect of soil type appeared in N, P, Ca, Mg, B, Mn and Zn concentrations in the plants. Plants with four to five leaves were infested with the third instar larvae of Bt-susceptible Plutella xylostella for 48 h, and samples of volatiles were collected and analysed. In the first experiment, the soil nutrient level had a significant effect on the emissions of (Z)-3-hexen-1-ol, (Z)-3-hexenyl acetate, hexyl acetate, (E)-4,8-dimethyl-1,3,7-non-atriene (DMNT), beta-elemene, gamma-bisabolene, alpha-bisabolene and (E)-nerolidol. The induction of these volatiles was significantly higher in infested conventional plants grown at a high-soil nutrient level compared to infested conventional plants at a low-soil nutrient level. In the second experiment, the soil nutrient level had a significant effect on the emissions of (Z)-3-hexen-1-ol, (Z)-3-hexenyl acetate and beta-elemene and, again, this was significantly higher in infested conventional plants grown at high-soil nutrient levels in comparison with infested plants at a low-soil nutrient level. In both experiments, the transgene effect was significant on the emissions of DMNT and (E,E)-alpha-farnesene. The differences in emissions between the two separate experiments suggest that growth conditions (particularly daylength) and sampling procedure may affect the ratio of compounds detected in the emission blend, even though the response to herbivory, nutrient availability and the transgene were similar.

Emission of Plutella xylostella-induced compounds from cabbages grown at elevated CO2 and orientation behavior of the natural enemies

Several plant species defend themselves indirectly from herbivores by producing herbivore-induced volatile compounds that attract the natural enemies of herbivores. Here we tested the effects of elevated atmospheric CO(2) (720 micromol mol(-1)) concentration on this indirect defense, physiological properties, and constitutive and induced emissions of white cabbage (Brassica oleracea ssp. capitata, cvs Lennox and Rinda). We monitored the orientation behavior of the generalist predator Podisus maculiventris (Heteroptera: Pentatomidae) and the specialist parasitoid Cotesia plutellae (Hymenoptera: Braconidae) to plants damaged by Plutella xylostella (Lepidoptera: Plutellidae) in the Y-tube olfactometer. Elevated CO(2) levels did not affect stomatal densities but reduced specific leaf area and increased leaf thickness in cv Lennox. In addition to enhanced constitutive monoterpene emission, P. xylostella-damaged cabbages emitted homoterpene (E)-4,8-dimethyl-1,3,7-nonatriene, sesquiterpene (E,E)-alpha-farnesene, and (Z)-3-hexenyl acetate. Growth at elevated CO(2) had no significant effect on the emissions expressed per leaf area, while minor reduction in the emission of homoterpene (E)-4,8-dimethyl-1,3,7-nonatriene and (E,E)-alpha-farnesene was observed at elevated CO(2) in one of two experiments. The generalist predator P. maculiventris discriminated only between the odors of intact and P. xylostella-damaged cv Rinda plants grown at ambient CO(2) concentration, preferring the odor of the damaged plants. The specialist parasitoid C. plutellae preferred the odor of damaged plants of both cultivars grown at ambient CO(2) but did not detect damaged cv Lennox plants grown at elevated CO(2). The results suggest that elevated atmospheric CO(2) concentration could weaken the plant response induced by insect herbivore feeding and thereby lead to a disturbance of signaling to the third trophic level.

Effect of zaprinast on nitric oxide levels in serum and aortic tissue

Nitric oxide (NO), which is synthesized from the guanidino nitrogen of l-arginine by nitric oxide synthase (NOS), plays an important role in many physiological and pathological processes. Most of the effects of NO are mediated by cyclic guanosine 3'5 monophosphate (cGMP), which is synthesized by soluble guanylate cyclase (sGC) and degraded by phosphodiesterases (PDEs). Although the NO/cGMP pathway has been extensively studied, remarkably little is known about the regulation of NO release. Furthermore, controversial studies have indicated that intervention of the sGC/cGMP pathway modulates the release of NO. The purpose of this study was to evaluate the hypothesis that drugs that affect the sGC/cGMP pathway may modulate NO release and, if so, is there a correlation between NO levels and blood pressure effect? To this end, we investigated the effects of the PDE 5 inhibitor zaprinast on mean arterial pressure (MAP), nitrite/nitrate levels and cGMP in normotensive male Sprague Dawley rats. The results of the current study indicated that zaprinast dose-dependently increased plasma cGMP levels at 18, 24 and 36 mg/kg and decreased MAP at 24 and 36 mg/kg. However, zaprinast at 18, 24 and 36 mg/kg did not affect NO levels either in serum or aortic tissue. We have concluded that the PDE 5 inhibitor zaprinast has no regulatory effect on NO release in serum and aortic tissue, and NO was not involved in the hypotensive effect of zaprinast.

Bioactive kaurane diterpenes and coumarins from Fortunella margarita

Two bioactive pyranocoumarins 1 (sesselin) and 3 (xanthyletin) and one prenylated coumarin 2 (suberosin), beside three rare kaurene diterpenes 5-7 were isolated from the roots of Fortunella margarita. Their structures were determined from their spectroscopic data, including 1H/13C 2D NMR experiments. The kaurene diterpenes 5-7 are reported in Rutaceae for the first time. Diterpene 5 was found to be a potent stimulator of uterine contraction; it also caused stimulation of brain activity.

Factor Xa (FXa) inhibitor from the nymphs of the camel tick Hyalomma dromedarii

An inhibitor of factor Xa (FXa) was isolated from the nymphs of the camel tick Hyalomma dromedarii by a combination of chromatography on DEAE-cellulose and Sephacryl S-300 columns. The isolated nymphal FXa inhibitor turned out to be a homogenous preparation of a single polypeptide chain (15 kDa) as judged by both the native and denatured SDS-PAGE. Its pI value ranged from 7.7 to 7.9. The inhibitor is a potent anticoagulant since it prolonged both the activated partial thromboplastin time (APTT) and the prothrombin time (PT) of the camel plasma in a concentration-dependent manner. Its activity was threefold lower toward thrombin than FXa, but it did not inhibit any of the proteases; trypsin, alpha-chymotrypsin, papain, pepsin and subtilisin. The inhibitor binds at two sites on FXa uncompetitively with an inhibition constant (K(i)) value of 134 nM.

Population-based health principles in medical and public health practice

Traditionally, medical education, research, and practice have focused on the care of the individual but an increasing emphasis on the care of populations has raised awareness among academic medical centers, integrated delivery systems, and managed care organizations of the value of embracing population-based health principles. Five principles are relevant in this regard: a community perspective, a clinical epidemiology perspective, evidence-based practice, an emphasis on outcomes, and an emphasis on prevention. This article describes these interrelated concepts together with specific strategies to effect implementation. Widespread awareness and adoption of these principles will have a profound impact on medical and public health education, practice, and ultimately the public's health.

Risks of fracture of Björk-Shiley 60 degree convexo-concave prosthetic heart valves: long-term cohort follow up in the UK, Netherlands and USA

BACKGROUND AND AIM OF THE STUDY

Approximately 82,000 Björk-Shiley convexo-concave (BSCC) 60 degree prosthetic heart valves were implanted in patients worldwide between 1979 and 1986. Outlet strut fractures (OSF) of some of the valves were first reported shortly after their introduction. Here, the determinants of OSF are examined, and the between-country variation and long-term risk are assessed.

METHODS

Cohorts of patients in the UK, Netherlands and USA with 15,770 BSCC 60 degree heart valves were followed up to 18 years for the occurrence of OSF.

RESULTS

Crude rates of OSF were highest in the UK (0.18% per year), intermediate in the Netherlands (0.13%), and lowest in the USA (0.06%), although risk factor adjustment reduced the inter-country differences. Furthermore, in the UK and Netherlands, OSF rates (particularly for mitral valves) declined with time since implantation, and between-country differences were considerably diminished 10 or more years post implantation. The risk of OSF decreased steadily with advancing patient age. Fracture rates were lower among women than men, and also varied significantly with valve size and position and OSF status of other valves in the same shoporder.

CONCLUSION

This long-term follow up of BSCC 60 degree heart valve patients indicates that risk factors for valve fracture are generally similar in the UK, Netherlands and USA. It also identifies a strong association between fracture risk and age, newly reveals gender-related differences, and shows that the risk of valve fracture persisted, albeit at a reduced rate, into the 1990s.

Isolation and properties of two forms of thrombin inhibitor from the nymphs of the camel tick Hyalomma dromedarii (Acari: Ixodidae)

Two forms of the nymphal thrombin inhibitors (NTI) 3.2 kDa and 14.9 kDa were purified by chromatography on CM-cellulose. Sephacryl S-300 and Sephadex G-50 columns and designated NTI- 1 and NTI-2 respectively. The NTI-2 turned out to be homogenous monomeric protein in both native-PAGE and denatured SDS-PAGE with M(r) value of 14.9 kDa approximately and its pI value ranged from 7.2 to 7.5. The NTI-1 and NTI-2 displayed anticoagulant activity since they prolonged both the activated partial thromboplastin time (APTT) and the prothrombin time (PT) of the camel plasma in a concentration-dependent manner. The potency of NTI-I toward thrombin was 5-fold higher than that toward FXa, while NTI-2 was 3-fold active toward FXa than thrombin. However, both of them did not inhibit any of the other examined proteases. The types of inhibition of thrombin by NTI-1 and NTI-2 were non-competitive and competitive with inhibition constants (Ki) values of 11.7 microM and 211 nM respectively. One binding site was deduced on thrombin for each inhibitor.

Molecular dating of senile plaques in the brains of individuals with Down syndrome and in aged dogs

beta-Amyloid (Abeta) is a constituent of senile plaques found with increasing age in individuals with Down syndrome (DS) and in the canine model of aging. Sections of DS and dog brain were immunostained using an affinity-purified polyclonal antibody for a posttranslationally modified Abeta with a racemized aspartate at position 7 (d7C16). The immunostaining characteristics of d7C16 Abeta in DS and dog brain indicate that it is present in all plaque subtypes, including the thioflavin-S-negative diffuse plaques that develop with age in dogs. The youngest DS case exhibited weak immunolabeling for d7C16 but the extent of d7C16-positive plaques increased with age. In addition, d7C16-positive plaques were initially found in clusters in the superficial layers of the frontal and entorhinal cortex but, with advancing age, increasing numbers appeared in deeper layers, suggesting a progression of Abeta deposition from superficial to deeper cortical layers. Ultrastructural studies in DS brain were confirmed using perfused dog brain and provided consistent results; thioflavin-S-negative diffuse plaques consist of fibrillar Abeta and racemized Abeta is associated with thicker and more highly interwoven fibrils than nonracemized Abeta. The use of antibodies to modified forms of the Abeta protein should provide insight into the progression of plaque pathology in DS and Alzheimer's disease brain.

The contributions of erosion, swelling, and porosity to theophylline release kinetics from Cissus populnea polymer matrices

The variable factors of erosion rate, swelling rate, and porosity were used in studying the release patterns of theophylline from our Cissus populnea polymer (CPP) matrices under the different factor combinations given by a simple 2n factorial experimental design. The zero-order slopes and correlation coefficients representing release rate and linearity, respectively, as obtained from both the nonsteady state and steady state were statistically treated. It appears that the nonsteady-state analysis is more suitable for studying the effects of individual factors, while the steady-state analysis appears more suitable for studying interaction effects of the factors. The study also showed that erosion is the main mechanism by which theophylline is released from the matrices, while swelling is responsible for maintaining linearity in the zero-order release curves. A careful examination of the statistical results shows some functional relationships between the factors, which should be considered in designing more detailed factorial experiments to enable the establishment of equation models for predicting the release profile of theophylline from our CPP matrices under any given dissolution condition.

Attenuation of fission neutrons by some hydrogeneous shield materials and the exponential dependence of the attenuated total neutron dose rate on the shield thickness

This work deals with the attenuation of fission neutrons by some hydrogeneous shield materials. The attenuated fission neutrons are described by the energy groups (fast, epithermal and thermal). The exponential decrease in the fast flux is represented by the removal cross section concept. Each of the epithermal and thermal fluxes is expressed using the diffusion equation including a pair of arbitrary constants to be determined using the corresponding boundary conditions. The solution obtained for the required arbitrary constants is then approximated in a simplified form such that it may easily replace the corresponding exact solution. The attenuation values, by which the neutron dose rate distributions are exponentially decreased through certain thicknesses are also determined for the given materials. They are compared to the corresponding experimental and theoretical data. The results obtained for the total neutron dose rate distributions in terms of a suitable range of layer thicknesses are then used to determine--for each material--an average value for the total neutron dose rate representing the exponential decrease during passage through the considered range of layer thicknesses.