Investigation of dissolution kinetics of a Nigerian columbite in hydrofluoric acid using the shrinking core model

A study of the kinetics of the dissolution of a Nigerian columbite in hydrofluoric acid has been examined and an investigation on the quantitative leaching of the mineral was also carried out. The effects of some parameters such as acid concentration, contact time and temperature were investigated. Elemental analysis of the ore was done using Particle-induced X-ray Emission (PIXE) spectroscopy with 2.5 MeV protons and this showed the major elements in the ore to be Si (8.82 %), Fe (10.74 %), Mn (4.72 %), Ta (6.80 %),Nb (28.90 %) and W(2.61%), with K, Ni, Zn, Sr and Y occurring in traces. Experimental results indicate that the dissolution rate is chemical reaction controlled, with reaction order of 0.57. Dissolution of over 90 % of the columbite was achieved in 5 h, using 20 M HF at 90 oC with 100 µm particle sizes. Activation energy, Ea of 15.70 KJ.mole-1 was obtained for the process. http://dx.doi.org/10.4314/njt.v35i4.1

Methodological considerations concerning the development of oral dental erosion indexes: literature survey, validity and reliability

Within the context of preventing non-communicable diseases, the World Health Report (2002) and the WHO Global Oral Health Program (2003) put forward a new strategy of disease prevention and health promotion. Greater emphasis is placed on developing global policies in oral health promotion and oral disease prevention. The Decayed, Missing, Filled Teeth (DMFT) index does not meet new challenges in the field of oral health. Dental erosion seems to be a growing problem, and in some countries, an increase in erosion of teeth is associated with an increase in the consumption of beverages containing acids. Therefore, within a revision of the WHO Oral Health Surveys Basic Methods, new oral disease patterns, e.g. dental erosion, have to be taken into account. Within the last 20 years, many studies on dental erosion have been carried out and published. There has been a rapid growth in the number of indexes quantifying dental erosion process in different age groups. However, these indexes are not comparable. This article discusses quality criteria which an index intended for assessing tooth erosion should possess

Laparoscopy in management of appendicitis in high-, middle-, and low-income countries: a multicenter, prospective, cohort study.

BACKGROUND: Appendicitis is the most common abdominal surgical emergency worldwide. Differences between high- and low-income settings in the availability of laparoscopic appendectomy, alternative management choices, and outcomes are poorly described. The aim was to identify variation in surgical management and outcomes of appendicitis within low-, middle-, and high-Human Development Index (HDI) countries worldwide. METHODS: This is a multicenter, international prospective cohort study. Consecutive sampling of patients undergoing emergency appendectomy over 6 months was conducted. Follow-up lasted 30 days. RESULTS: 4546 patients from 52 countries underwent appendectomy (2499 high-, 1540 middle-, and 507 low-HDI groups). Surgical site infection (SSI) rates were higher in low-HDI (OR 2.57, 95% CI 1.33-4.99, p = 0.005) but not middle-HDI countries (OR 1.38, 95% CI 0.76-2.52, p = 0.291), compared with high-HDI countries after adjustment. A laparoscopic approach was common in high-HDI countries (1693/2499, 67.7%), but infrequent in low-HDI (41/507, 8.1%) and middle-HDI (132/1540, 8.6%) groups. After accounting for case-mix, laparoscopy was still associated with fewer overall complications (OR 0.55, 95% CI 0.42-0.71, p < 0.001) and SSIs (OR 0.22, 95% CI 0.14-0.33, p < 0.001). In propensity-score matched groups within low-/middle-HDI countries, laparoscopy was still associated with fewer overall complications (OR 0.23 95% CI 0.11-0.44) and SSI (OR 0.21 95% CI 0.09-0.45). CONCLUSION: A laparoscopic approach is associated with better outcomes and availability appears to differ by country HDI. Despite the profound clinical, operational, and financial barriers to its widespread introduction, laparoscopy could significantly improve outcomes for patients in low-resource environments. TRIAL REGISTRATION: NCT02179112

Pooled analysis of WHO Surgical Safety Checklist use and mortality after emergency laparotomy

Background The World Health Organization (WHO) Surgical Safety Checklist has fostered safe practice for 10 years, yet its place in emergency surgery has not been assessed on a global scale. The aim of this study was to evaluate reported checklist use in emergency settings and examine the relationship with perioperative mortality in patients who had emergency laparotomy. Methods In two multinational cohort studies, adults undergoing emergency laparotomy were compared with those having elective gastrointestinal surgery. Relationships between reported checklist use and mortality were determined using multivariable logistic regression and bootstrapped simulation. Results Of 12 296 patients included from 76 countries, 4843 underwent emergency laparotomy. After adjusting for patient and disease factors, checklist use before emergency laparotomy was more common in countries with a high Human Development Index (HDI) (2455 of 2741, 89.6 per cent) compared with that in countries with a middle (753 of 1242, 60.6 per cent; odds ratio (OR) 0.17, 95 per cent c.i. 0.14 to 0.21, P <0001) or low (363 of 860, 422 per cent; OR 008, 007 to 010, P <0.001) HDI. Checklist use was less common in elective surgery than for emergency laparotomy in high-HDI countries (risk difference -94 (95 per cent c.i. -11.9 to -6.9) per cent; P <0001), but the relationship was reversed in low-HDI countries (+121 (+7.0 to +173) per cent; P <0001). In multivariable models, checklist use was associated with a lower 30-day perioperative mortality (OR 0.60, 0.50 to 073; P <0.001). The greatest absolute benefit was seen for emergency surgery in low- and middle-HDI countries. Conclusion Checklist use in emergency laparotomy was associated with a significantly lower perioperative mortality rate. Checklist use in low-HDI countries was half that in high-HDI countries.Peer reviewe

Rapid reprogramming of epigenetic and transcriptional profiles in mammalian culture systems

BackgroundThe DNA methylation profile of mammalian cell lines differs from the primary tissue from which they were derived, exhibiting increasing divergence from the in vivo methylation profile with extended time in culture. Few studies have directly examined the initial epigenetic and transcriptional consequences of adaptation of primary mammalian cells to culture, and the potential mechanisms through which this epigenetic dysregulation occurs is unknown.ResultsWe demonstrate that adaptation of mouse embryonic fibroblast, MEFS, to cell culture results in a rapid reprogramming of epigenetic and transcriptional states. We observed global 5-hydroxymethylcytosine (5hmC) erasure within three days of culture initiation. Loss of genic 5hmC was independent of global 5-methylcytosine (5mC) levels and could be partially rescued by addition of Vitamin C. Significantly, 5hmC loss was not linked to concomitant changes in transcription. Discrete promoter-specific gains of 5mC were also observed within seven days of culture initiation. Against this background of global 5hmC loss we identified a handful of developmentally important genes that maintained their 5hmC profile in culture, including the imprinted loci Gnas and H19. Similar outcomes were identified in the adaption of CD4+ T-cells to culture.ConclusionsWe report a dramatic and novel consequence of adaptation of mammalian cells to culture in which global loss of 5hmC occurs; suggesting rapid concomitant loss of methylcytosine dioxygenase activity. The observed epigenetic and transcriptional re-programming occurs much earlier than previously assumed, and has significant implications for the use of cell lines as faithful mimics of in vivo epigenetic and physiological processes.We thank Professors Adrian Bird and Nicholas Hastie for their comments on our manuscript. JT and RO are funded by IMI-MARCAR (under grant agreement number (115001) (MARCAR project)). Work in RM's lab is supported by the MRC, IMI-MARCAR and the BBSRC. This work in RM's lab was also initially funded by the Breakthrough Breast Cancer charity. Work in MB's lab was supported by Linkoping University strategic research funding and the Ake Wibergs fund (3772738). Work in SP's lab is supported by the BBSRC.</p

Global variation in anastomosis and end colostomy formation following left-sided colorectal resection

Background End colostomy rates following colorectal resection vary across institutions in high-income settings, being influenced by patient, disease, surgeon and system factors. This study aimed to assess global variation in end colostomy rates after left-sided colorectal resection. Methods This study comprised an analysis of GlobalSurg-1 and -2 international, prospective, observational cohort studies (2014, 2016), including consecutive adult patients undergoing elective or emergency left-sided colorectal resection within discrete 2-week windows. Countries were grouped into high-, middle- and low-income tertiles according to the United Nations Human Development Index (HDI). Factors associated with colostomy formation versus primary anastomosis were explored using a multilevel, multivariable logistic regression model. Results In total, 1635 patients from 242 hospitals in 57 countries undergoing left-sided colorectal resection were included: 113 (6·9 per cent) from low-HDI, 254 (15·5 per cent) from middle-HDI and 1268 (77·6 per cent) from high-HDI countries. There was a higher proportion of patients with perforated disease (57·5, 40·9 and 35·4 per cent; P < 0·001) and subsequent use of end colostomy (52·2, 24·8 and 18·9 per cent; P < 0·001) in low- compared with middle- and high-HDI settings. The association with colostomy use in low-HDI settings persisted (odds ratio (OR) 3·20, 95 per cent c.i. 1·35 to 7·57; P = 0·008) after risk adjustment for malignant disease (OR 2·34, 1·65 to 3·32; P < 0·001), emergency surgery (OR 4·08, 2·73 to 6·10; P < 0·001), time to operation at least 48 h (OR 1·99, 1·28 to 3·09; P = 0·002) and disease perforation (OR 4·00, 2·81 to 5·69; P < 0·001). Conclusion Global differences existed in the proportion of patients receiving end stomas after left-sided colorectal resection based on income, which went beyond case mix alone

Repugnancy clause and its impact on customary law: Comparing the South African and Nigerian positions — Some lessons for Nigeria

The repugnancy doctrine was introduced into Nigeria in the 19 th century through thereceived English laws. This doctrine prescribes that the courts shall not enforce any customary law rule if it is contrary to public policy or repugnant to natural justice, equity and good conscience. The doctrine is generally criticised for its use of foreign standards to assess the validity of the customary law rules. This article, however, contends that repugnancy doctrine had played a positive role in the development of customary law in Nigeria by removing its harsh aspects. Most African countries repealed the repugnancy provisos when they obtained independence but Nigeria still retains it. The article compares the positions in South Africa and Nigeria. In the South African context, this article found that repugnancy proviso had outlived its usefulness and courts now apply customary law subject to the Constitution and any legislation that specifically deals with customary law. This position, the article commends for Nigeria.Teenstrydigheidsleerstelling en sy impak op gewoontereg: Vergelyking van Suid-Afrika en Nigerie se posisies — ’n Paar lesse vir Nigerie: Die teenstrydigheidsleerstelling was aan Nigerie bekend gestel in die 19de eeu deur die ontvangs van die Engelse reg. Die leerstelling skryf voor dat die howe nie enige gewoontereg sal toepas as dit teenstrydig is met openbare beleid of onverenigbaar is met natuurlike geregtigheid, billikheid en skoon gewete. Die leerstelling word oor die algemeen gekritiseer oor die gebruik van vreemde standaarde om die geldigheid van die gewoonteregtelike reels te bepaal. Hierdie artikel voer egter aan dat die teenstrydigheidsleerstelling ’n positiewe rol in die ontwikkeling van gewoontereg in Nigerie gespeel het deur met die growwe aspekte weg te doen. Meeste Afrika-lande het die teenstrydige stipulasies afgeskaf nadat hulle onafhanklikheid verkry het maar Nigerie het dit steeds behou. Die artikel vergelyk die posisies in Suid-Afrika en Nigerie. In die Suid-Afrikaanse konteks het die artikel gevind dat teenstrydige stipulasies sy bruikbaarheid oorleef het en howe pas nou gewoontereg toe onderworpe aan die Grondwet en enige wetgewing wat spesifiek handel oor gewoontereg. Hierdie artikel beveel hierdie posisie aan vir Nigerie

Utilization of crop residues and Agro-industrial by-products as complete diets for West African dwarf sheep and goats

No Abstract