Fate of hydroxyapatite nano particles during in vitro gastrointestinal digestion : a thesis presented in partial fulfilment of the requirements for the degree of Master in Food Technology at Massey University, Riddet Institute and Massey Institute of Food Science and Technology, Palmerston North, New Zealan

The following figures have been removed for copyright reasons, but may be accessed through their sources listed in the References: Figures 2.2 (Yada et al., 2014, Fig.1), 2.3 (Rivera-Munoz, 2011), 2.4 (Sakae et al., 2015, Fig. 2 & 3), 2.5 (Ehrlich et al., 2009, Fig. 3), 2.6 (Lynn & Bonfield, 2005, Fig. 1), 2.7 (Ehrlich et al., 2009, Fig. 6), 2.8 (Mafé et al., 1992, Fig. 1), 2.9 (Gaucheron et al., 2005, Fig. 2). Composite Figure 2.10 remains for clarity's sake.There is an increasing change in population demographics towards an aging population in the world, which had led to the availability of various commercial nutritionally supplemented products. Hydroxyapatite (HA), with chemical formula Ca10(PO4)6(OH)2, is an insoluble calcium salt used for calcium supplementation because of its similarity to the minerals found in human bone and teeth. The insoluble calcium salts are preferred over the soluble ones because of their high heat stability during milk processing under high heat treatment. However, the drawback of insoluble calcium salts is the tendency to sediment during storage resulting in unfavourable gritty texture. Thus, reduction in particle sizes into micron to nano-size improves the dispersion of these insoluble salts. However, the application of nano-sized particles in food products have raised concerns from both the regulatory organizations and consumers on the implications related to both the environmental and health safety aspects. Thus, the objective of the study is to determine the digestion behaviour of nano-sized needle/rod shaped HA (nHA) when added into skim milk during in vitro gastrointestinal digestion. Determination of calcium such as soluble and ionic calcium was conducted to determine the dissolution of nHA. The structural changes and the crystallographic changes of nHA were determined using electron microscopy and x-ray diffraction techniques. The results of in vitro gastric digestion showed presence of undissolved nHA particles even after 240 min of gastric and 120 min of intestinal digestion when examined under TEM, while the XRD analysis detected the presence of crystalline nHA in the first 120 min of gastric digestion. Thus, the possible mechanisms leading to the incomplete dissolution of nHA under acidic conditions of the stomach are discussed subsequently

PSYCHOLOGICAL STATUS DURING COVID-19 PANDEMIC AMONG THE GENERAL POPULATION IN BHUTAN

Background: Since the outbreak of the novel coronavirus disease-19 (COVID-19) on 31 December 2019 in Wuhan (Hubei, China), an increasing amount of information, concern, and restrictive public health measures put on to contain the spread of infection have impacted the mental health of the people. The psychological status of the Bhutanese population during this novel coronavirus disease-19 (COVID-19) pandemic is unknown.Aim: To measure the levels of stress, anxiety, and depression in Bhutanese population during the COVID-19 pandemic. The study also aimed to explore the potential differences in psychological status between the demographic variables.Methods and material: A cross-sectional web-based survey was done using a non-probabilistic snowball sampling methodology. Data were collected using the socio-demographic data questionnaire and the Depression Anxiety and Stress scale-21 (DASS-21). Descriptive statistics were used to describe the data, and independent t-tests and analyses of variance (ANOVAs) were used to compare the psychological status among different groups.Results: A total of 663 respondents were recruited. Of them, 21.27% of the participants reported mild to severe levels of depression, 25.04% reported mild to severe levels of anxiety, and 10.56% were stressed. Young and those unemployed during the pandemic showed greater negative psychological symptoms.Conclusion: The results show that psychological problems are prevalent during the COVID-19 pandemic. The findings can help government and health professionals safeguard the psychological wellbeing of the community in the face of COVID-19 outbreak in Bhutan and worldwide

Population size estimates of transgender women and transgender men in Bhutan, 2020.

Population size estimates of transgender women and transgender men in Bhutan, 2020.</p

Gender and sexual identities of transgender women and men, Bhutan, 2020.

Gender and sexual identities of transgender women and men, Bhutan, 2020.</p

Population abundance and distribution of the endangered golden langur (Trachypithecus geei, Khajuria 1956) in Bhutan

Reliable population estimates are lacking for many South Asian primate species, including the golden langur (Trachypithecus geei), which is endangered and restricted to Bhutan and northeast India. Although well studied in India, few studies exist on this species in Bhutan. In November 2017, we undertook a nationwide survey of golden langurs in Bhutan using double observers along trail-based transects in 17 blocks within its habitat, and modeled its distribution using MaxEnt. A total of 2439 golden langurs in 222 groups were collectively encountered by 17 teams of double observers, from which, an overall population of 2516 ± SE 363 individuals and 236 ± SE 9 groups were estimated. Group sizes varied from 2 to 35 individuals with a mean of 11 ± SD 0.38 individuals. A total of 468 adult males (19%), 924 adult females (38%), 649 juveniles (27%), and 398 infants (16%) were counted. Adult male-to-female sex ratio was 1:1.97 and adult female-to-infant ratio was 1:0.43. We determined 2848 km² of suitable area for golden langurs in Bhutan and estimated a density of 0.88 individuals/km². Our population estimate of golden langurs in Bhutan is much lower than the current IUCN estimate of 4000 individuals for Bhutan, necessitating a reassessment of its current conservation status due to threats from road kills, electrocution, and development activities like road construction, hydropower, and electrical transmission lines. We further recommend our refined double-observer survey method to reliably estimate primate populations in rugged terrain