All Stories

  1. Predicting consumer demand for healthy snacks: a cross-sectional study of young Pakistaniworking mothers
  2. Development and Characterization of Chicken Eggshell-Derived Untreated and Treated-Biogenic Hydroxyapatite-Fortified Candy and Consumer Acceptance by Using the Just-About-Right Method
  3. Improving the quality and digestibility of wheat flour starch and protein for noodles through ultrasound, high hydrostatic pressure, and plasma technologies: A review
  4. Modified risk calculator for the Pakistani population based on perceived versus actual risk factors for developing type 2 diabetes mellitus
  5. Global, regional, and national stillbirths at 20 weeks' gestation or longer in 204 countries and territories, 1990–2021: findings from the Global Burden of Disease Study 2021
  6. Recent Research Advances in Meat Analogues: A Comprehensive Review on Production, Protein Sources, Quality Attributes, Analytical Techniques Used, and Consumer Perception
  7. Global, regional, and national burden of stroke and its risk factors, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021
  8. Low FODMAP diets—Boon or bane for individuals with GI disorders
  9. Downstream Processing, Functional Properties, and Applications of Extracted Proteins from Nonconventional Sources for Improving Food Sustainability
  10. Optimization of ultrasonic‐assisted extraction of soluble dietary fiber (β‐glucan) from different barley varieties and study of its characterization and functional attributes
  11. Quantitative and qualitative approach for accessing and predicting food safety using various web-based tools
  12. Formulation and evaluation of functional attributes of low‐fat mozzarella cheese using aloe vera mucilage as a potential fat replacer
  13. Formulation and Characterization of Lentil Milk–Based Soft Cheese Analogs: Insights on Physicochemical and Textural Properties
  14. Pulsed Light for Fresh Quality Preservation of Fruits and Vegetables
  15. Emerging insights into nutrition in pediatric metabolic disease: A comprehensive review of the Second Pediatric Nutrition Conference organized by the College of Health Sciences, Qatar University, Doha, Qatar
  16. Information-seeking behaviors, attitudes and beliefs about pregnancy-related nutrition and supplementation in different communities of Pakistan
  17. Valorization of plant proteins for meat analogues design—a comprehensive review
  18. Food waste: The paradox that continues to undermine food and nutrition security worldwide
  19. Global burden of 288 causes of death and life expectancy decomposition in 204 countries and territories and 811 subnational locations, 1990–2021: a systematic analysis for the Global Burden of Disease Study 2021
  20. Global incidence, prevalence, years lived with disability (YLDs), disability-adjusted life-years (DALYs), and healthy life expectancy (HALE) for 371 diseases and injuries in 204 countries and territories and 811 subnational locations, 1990–2021: a syst...
  21. Burden of disease scenarios for 204 countries
  22. Formulation and Quality Evaluation of Chicken Nuggets Supplemented with Beef and Chicken Livers
  23. Formulation and characterisation of low‐fat mozzarella cheese using basil seed mucilage: insights on microstructure and functional attributes
  24. Formulation of Chicken Nuggets Supplemented with Mutton and Fish Livers: Insights from Antioxidant and Textural Studies
  25. Applications of Strain‐Specific Probiotics in the Management of Cardiovascular Diseases: A Systemic Review
  26. Formulation and assessment of chickpea pulao using fenugreek seeds and Indian rennet to improve blood glycemic levels
  27. Herbal diets: Directions for improving health and wellness
  28. Global Health Trends 1950–2021: Impact of COVID-19 on Mortality and Population Growth
  29. Global fertility in 204 countries and territories, 1950–2021, with forecasts to 2100: a comprehensive demographic analysis for the Global Burden of Disease Study 2021
  30. Recent advances in applications of marine hydrocolloids for improving bread quality
  31. Formulation of Whole Wheat Bitter Gourd-Supplemented Cookies for Improving Blood Glycemic Levels: Insights of Inhibition Assays and Antioxidant Activities
  32. Probing the microbial diversity and probiotic candidates from Pakistani foods: isolation, characterization, and functional profiling
  33. Recent trends in hydrogen-associated treatments for maintaining the postharvest quality of fresh and fresh-cut fruits and vegetables: A review
  34. Impact of carbonated beverages on early onset of osteoporosis: A narrative review
  35. Prevalence, years lived with disability, and trends in anaemia burden by severity and cause, 1990–2021: findings from the Global Burden of Disease Study 2021
  36. Effects of different fat replacers on functional and rheological properties of low-fat mozzarella cheeses: A review
  37. Recent trends and policy shifts on empowering breastfeeding in developing countries
  38. Alcoholic Off-Flavor Disorders in Fresh Fruits
  39. Formulation of Edible Coatings from Alfalfa Saponins to Enhance the Postharvest Quality of Tomatoes
  40. Combination of enzymatically hydrolyzed potato powder with skimmed milk powder on the quality improvements of yogurt during refrigeration storage
  41. Selection of processed and packaged potato-based snacks among university students: a cross-sectional study regarding food environment and dietary behavior
  42. Nutrigenetics and nutrigenomics, and precision nutrition
  43. Quality Assessment of Fried Oils from Different Street Food Vendors and Restaurants in Different Areas of Gilgit, Pakistan
  44. Sustainable nutrition – healthy populations
  45. POTENTIAL CHALLENGES AND THREATS ASSOCIATED WITH PINE NUT CULTIVATION AND MARKETING IN PAKISTAN
  46. The state of health in Pakistan and its provinces and territories, 1990–2019: a systematic analysis for the Global Burden of Disease Study 2019
  47. Optimization and cholesterol-lowering activity of exopolysaccharide from Lactiplantibacillus paraplantarum NCCP 962
  48. Assessing the Effectiveness of Saponins from Alfalfa (Medicago sativa L.) to Mitigate Cypermethrin Residues in Apples
  49. Effect of Beef Fat Replacement with Linseed Oil Emulsions on Physicochemical and Sensory Properties of Beef Patties
  50. Optimization, fractional characterization, and antioxidant potential of exopolysaccharides from Levilactobacillus brevis NCCP 963 isolated from “kanji”
  51. Global perspective on food fraud with special emphasis on the prevalence of food fraud practices and policies in Pakistan
  52. Anthocyanin Delivery Systems: A Critical Review of Recent Research Findings
  53. Food irradiation technology: Prospects and future applications
  54. Editorial: Changes in eating habits, nutrition trends, and lifestyle-associated factors in the wake of the COVID-19 pandemic
  55. Effect of Food Quality and Nutritional Attributes on Consumer Choices during the COVID-19 Pandemic
  56. Editorial
  57. Technological advances in supply chain of processed foods during COVID-19: a review
  58. Solid Fuel Use and Health in Developing Countries
  59. Microstructural study of enzymatically and non‐enzymatically hydrolyzed potato powder
  60. Development, characterization, and principal component analysis of fish bone‐based fortified refined wheat flour tortilla and its organoleptic attributes
  61. Therapeutic Potential of Marine Bioactive Peptides against Human Immunodeficiency Virus: Recent Evidence, Challenges, and Future Trends
  62. Formulation and evaluation of functional attributes of low‐fat mozzarella cheese using okra mucilage as a fat replacer
  63. Efficient water removal from water-in-oil emulsions by high electric field demulsification
  64. Measuring the availability of human resources for health and its relationship to universal health coverage for 204 countries and territories from 1990 to 2019: a systematic analysis for the Global Burden of Disease Study 2019
  65. Editorial
  66. Recent Developments in Starch-Based Delivery Systems of Bioactive Compounds: Formulations and Applications
  67. Editorial
  68. Developing novel foods using multiple emulsions: insights with reference to bioaccessibility and bioavailability
  69. Plant-based meat analogs: A review with reference to formulation and gastrointestinal fate
  70. Profiling of Essential Mineral Content, Heavy Metals, and Bacterial Contaminants in Conventional and Organic Eggs Available in the Hypermarkets of the Eastern Province of Saudi Arabia
  71. Characterisation of O/W emulsions encapsulating ergocalciferol using onion skin waste saponins: insights on formulation and release properties
  72. Analgesic effect of ginger and peppermint on adolescent girls with primary dysmenorrhea
  73. Review on physicochemical, medicinal and nutraceutical properties of poppy seeds: a potential functional food ingredient
  74. Global, regional, and national sex-specific burden and control of the HIV epidemic
  75. Global, regional, and national mortality among young people aged 10–24 years, 1950–2019: a systematic analysis for the Global Burden of Disease Study 2019
  76. Phytochemical constituents and biological properties of domesticated capsicum species: a review
  77. Utilization of diverse protein sources for the development of protein-based nanostructures as bioactive carrier systems: A review of recent research findings (2010–2021)
  78. COVID-19 Pandemic and Food Safety Issues in Pakistan
  79. Fabrication and Characterization of Dodecenyl Succinic Anhydride Modified Kudzu Starch
  80. Assessment of different heavy metals in cigarette filler and ash from multiple brands retailed in Saudi Arabia
  81. Child Mortality Trends and Targets: GBD 2019 Findings
  82. Food Security Challenges for Pakistan During the COVID-19 Pandemic
  83. Effect of enzymatically hydrolyzed potato powder on quality characteristics of stirred yogurt during cold storage
  84. Correction to: Zafaria cholistanensis gen. nov. sp. nov., a moderately thermotolerant and halotolerant actinobacterium isolated from Cholistan desert soil of Pakistan
  85. Subnational mapping of HIV incidence and mortality among individuals aged 15–49 years in sub-Saharan Africa, 2000–18: a modelling study
  86. Synthesis of diosgenin conjugated gold nanoparticles using algal extract of Dictyosphaerium sp. and in-vitro application of their antiproliferative activities
  87. Formulation and characterization of yogurt prepared with enzymatically hydrolyzed potato powder and whole milk powder
  88. Food security challenges for Pakistan during COVID‐19 pandemic: An overview of the response plan
  89. A comprehensive review on chlorpyrifos toxicity with special reference to endocrine disruption: Evidence of mechanisms, exposures and mitigation strategies
  90. Zafaria cholistanensis gen. nov. sp. nov., a moderately thermotolerant and halotolerant actinobacterium isolated from Cholistan desert soil of Pakistan
  91. Mapping subnational HIV mortality in six Latin American countries with incomplete vital registration systems
  92. Application of Bioplastics in Agro-Based Industries and Bioremediation
  93. Application of nano/microencapsulated ingredients in drinks and beverages
  94. Scleroglucan and Schizophyllan
  95. Comparative study of oil-in-water emulsions encapsulating fucoxanthin formulated by microchannel emulsification and high-pressure homogenization
  96. Groundnut (Peanut) (Arachis hypogaea)
  97. Safflower (Carthamus tinctorius) Seed
  98. Fabrication of oil‐in‐water emulsions as shelf‐stable liquid non‐dairy creamers: effects of homogenization pressure, oil type, and emulsifier concentration
  99. Five insights from the Global Burden of Disease Study 2019
  100. Global age-sex-specific fertility, mortality, healthy life expectancy (HALE), and population estimates in 204 countries and territories, 1950–2019: a comprehensive demographic analysis for the Global Burden of Disease Study 2019
  101. Global burden of 369 diseases and injuries in 204 countries and territories, 1990–2019: a systematic analysis for the Global Burden of Disease Study 2019
  102. Global burden of 87 risk factors in 204 countries and territories, 1990–2019: a systematic analysis for the Global Burden of Disease Study 2019
  103. Mapping geographical inequalities in access to drinking water and sanitation facilities in low-income and middle-income countries, 2000–17
  104. Formulation and characterization of food grade O/W nanoemulsions encapsulating quercetin and curcumin: Insights on enhancing solubility characteristics
  105. Estimating global injuries morbidity and mortality: methods and data used in the Global Burden of Disease 2017 study
  106. Mapping geographical inequalities in oral rehydration therapy coverage in low-income and middle-income countries, 2000–17
  107. Author Correction: Mapping local patterns of childhood overweight and wasting in low- and middle-income countries between 2000 and 2017
  108. Naegleria fowleri: Swimming with Death as the Major Outbreak in Pakistan
  109. Mapping geographical inequalities in childhood diarrhoeal morbidity and mortality in low-income and middle-income countries, 2000–17: analysis for the Global Burden of Disease Study 2017
  110. Department of Error
  111. Insights on comparative bacterial diversity between different arid zones of Cholistan Desert, Pakistan
  112. Global injury morbidity and mortality from 1990 to 2017: results from the Global Burden of Disease Study 2017
  113. Mapping local patterns of childhood overweight and wasting in low- and middle-income countries between 2000 and 2017
  114. Screening and stability testing of commercially applicable Heliotropium crispum silver nanoparticle formulation with control over aging and biostability
  115. Layer-by-Layer Electrostatic Deposition of Edible Coatings for Enhancing the Storage Stability of Fresh-Cut Lotus Root (Nelumbo nucifera)
  116. Comparing public and private hospitals’ service quality
  117. Burden of injury along the development spectrum: associations between the Socio-demographic Index and disability-adjusted life year estimates from the Global Burden of Disease Study 2017
  118. Preparation of monodisperse O/W emulsions using a crude surface-active extract from argan by-products in microchannel emulsification
  119. Encapsulation of Pigmented Lipophilic Antioxidants Through Micro and Nano-emulsions
  120. Formulation and characterization of oil-in-water nanoemulsions stabilized by crude saponins isolated from onion skin waste
  121. Comparative safety analysis of bactericidal nano-colloids: Assessment of potential functional toxicity and radical scavenging action
  122. Global, regional, and national incidence, prevalence, and mortality of HIV, 1980–2017, and forecasts to 2030, for 195 countries and territories: a systematic analysis for the Global Burden of Diseases, Injuries, and Risk Factors Study 2017
  123. Formulation and characterisation of O/W emulsions stabilised with modified seaweed polysaccharides
  124. Vitamin D deficiency in Pakistani population: critical overview from 2008 to 2018
  125. Clinical investigation to modulate the effect of fenugreek polysaccharides on type-2 diabetes
  126. Formulation of active packaging system using Artemisia scoparia for enhancing shelf life of fresh fruits
  127. Phalsa (Grewia asiatica L) fruit berry a promising functional food ingredient: A comprehensive review
  128. Fucoxanthin-Loaded Oil-in-Water Emulsion-Based Delivery Systems: Effects of Natural Emulsifiers on the Formulation, Stability, and Bioaccessibility
  129. Department of Error
  130. Opportunities and challenges for functional and medicinal beverages: Current and future trends
  131. Health/nutritional status of immigrant Pakistani laborers working in the Kingdom of Saudi Arabia
  132. Estimates and burden of foodborne pathogens in RTE beverages in relation to vending practices
  133. Global, regional, and national burden of traumatic brain injury and spinal cord injury, 1990–2016: a systematic analysis for the Global Burden of Disease Study 2016
  134. Complex coacervates from gelatin and octenyl succinic anhydride modified kudzu starch: Insights of formulation and characterization
  135. Complex coacervation: Principles, mechanisms and applications in microencapsulation
  136. Lab-on-a-chip techniques for high-throughput proteomics and drug discovery
  137. Whey Protein-Based Functional Energy Drinks Formulation and Characterization
  138. Global, regional, and national age-sex-specific mortality for 282 causes of death in 195 countries and territories, 1980–2017: a systematic analysis for the Global Burden of Disease Study 2017
  139. Global, regional, and national comparative risk assessment of 84 behavioural, environmental and occupational, and metabolic risks or clusters of risks for 195 countries and territories, 1990–2017: a systematic analysis for the Global Burden of Disease ...
  140. Global, regional, and national disability-adjusted life-years (DALYs) for 359 diseases and injuries and healthy life expectancy (HALE) for 195 countries and territories, 1990–2017: a systematic analysis for the Global Burden of Disease Study 2017
  141. Global, regional, and national incidence, prevalence, and years lived with disability for 354 diseases and injuries for 195 countries and territories, 1990–2017: a systematic analysis for the Global Burden of Disease Study 2017
  142. Measuring progress of the health-related Sustainable Development Goals for 195 countries
  143. Global, regional, and national age-sex-specific mortality and life expectancy, 1950–2017: a systematic analysis for the Global Burden of Disease Study 2017
  144. Population and fertility by age and sex for 195 countries and territories, 1950–2017: a systematic analysis for the Global Burden of Disease Study 2017
  145. Department of Error
  146. Dengue death tolls: A nightmare for Khyber Pakhtunkhwa, Pakistan
  147. Gypenosides as natural emulsifiers for oil-in-water nanoemulsions loaded with astaxanthin: Insights of formulation, stability and release properties
  148. A Question Mark on Emerging Zinc-Related Nutritional Deficiencies in Pakistani Population
  149. Microencapsulation of betanin in monodisperse W/O/W emulsions
  150. Formulation and characterization of astaxanthin-enriched nanoemulsions stabilized using ginseng saponins as natural emulsifiers
  151. Formulation and characterization of water-in-oil nanoemulsions loaded with açaí berry anthocyanins: Insights of degradation kinetics and stability evaluation of anthocyanins and nanoemulsions
  152. Formulation and stabilization of oil-in-water nanoemulsions using a saponins-rich extract from argan oil press-cake
  153. Ginseng phytochemicals as therapeutics in oncology: Recent perspectives
  154. Long-term stability of droplet production by microchannel (step) emulsification in microfluidic silicon chips with large number of terraced microchannels
  155. Emulsion stability of clove oil in chitosan and sodium alginate matrix
  156. Insights into the Thermophile Diversity in Hot Springs of Pakistan
  157. Dietary Fibers in Modern Food Production: A Special Perspective With β-Glucans
  158. In silicofunctional and tumor suppressor role of hypothetical protein PCNXL2 with regulation of the Notch signaling pathway
  159. Formulation and characterization of O/W nanoemulsions encapsulating high concentration of astaxanthin
  160. Comparison of ergocalciferol nanodispersions prepared using modified lecithin and sodium caseinate: Insights of formulation, stability and bioaccessibility
  161. Formulation and characterization of O/W emulsions stabilized using octenyl succinic anhydride modified kudzu starch
  162. In vitro bioaccessibility of ergocalciferol in nanoemulsion-based delivery system: the influence of food-grade emulsifiers with different stabilising mechanisms
  163. Hydrogels incorporated with silver nanocolloids prepared from antioxidant rich Aerva javanica as disruptive agents against burn wound infections
  164. Formulation and characterization of monodisperse O/W emulsions encapsulating astaxanthin extracts using microchannel emulsification: Insights of formulation and stability evaluation
  165. Asymmetrical Microchannel Emulsification Plates for Production of Small-Sized Monodispersed Emulsion Droplets
  166. A comprehensive characterisation of safflower oil for its potential applications as a bioactive food ingredient - A review
  167. Formulation and characterization of oil-in-water emulsions stabilized by gelatinized kudzu starch
  168. Microchannel emulsification: A promising technique towards encapsulation of functional compounds
  169. A review on chemistry and pharmacology of Ajwa date fruit and pit
  170. Comparative studies of three novel freshwater microalgae strains for synthesis of silver nanoparticles: insights of characterization, antibacterial, cytotoxicity and antiviral activities
  171. Encapsulation of β-sitosterol plus γ-oryzanol in O/W emulsions: Formulation characteristics and stability evaluation with microchannel emulsification
  172. Recent lab‐on‐chip developments for novel drug discovery
  173. Comparative analysis of stability and biological activities of violacein and starch capped silver nanoparticles
  174. ISOLATION, MOLECULAR IDENTIFICATION AND CHARACTERIZATION OF BORON-TOLERANT BACTERIAL STRAINS FROM SEWAGE TREATMENT POND OF ISLAMABAD, PAKISTAN
  175. Encapsulation of cholecalciferol and ergocalciferol in oil‐in‐water emulsions by different homogenization techniques
  176. Formulation and characterization of food grade water‐in‐oil emulsions encapsulating mixture of essential amino acids
  177. Emerging Technologies for Recovery of Value-Added Components from Olive Leaves and Their Applications in Food/Feed Industries
  178. Formulation and characterization of esterified xylo-oligosaccharides-stabilized oil-in-water emulsions using microchannel emulsification
  179. Formulation and stability assessment of ergocalciferol loaded oil-in-water nanoemulsions: Insights of emulsifiers effect on stabilization mechanism
  180. Microchannel emulsification study on formulation and stability characterization of monodisperse oil-in-water emulsions encapsulating quercetin
  181. Controlled assembly of silver nano-fluid in Heliotropium crispum extract: A potent anti-biofilm and bactericidal formulation
  182. Streptomyces caldifontis sp. nov., isolated from a hot water spring of Tatta Pani, Kotli, Pakistan
  183. Simulation of oleuropein structural conformation in vacuum, water and triolein–water systems using molecular dynamics
  184. FLOWERING AND FRUITING RESPONSES OF STRAWBERRY TO GROWTH HORMONE AND CHILLING GROWN UNDER TUNNEL CONDITIONS
  185. Effect of esterified oligosaccharides on the formation and stability of oil-in-water emulsions
  186. BIODEGRADATION OF PHENOL BY STENOTROPHOMONAS SP. AND STAPHYLOCOCCUS SP. ISOLATED FROM CONTAMINATED SITES
  187. Preparation and physical property assessments of liquid-core hydrogel beads loaded with burdock leaf extract
  188. Salt and drought stresses in safflower: a review
  189. Monodisperse aqueous microspheres encapsulating high concentration of l-ascorbic acid: insights of preparation and stability evaluation from straight-through microchannel emulsification
  190. Evaluation of Glucose Dehydrogenase and Pyrroloquinoline Quinine (pqq) Mutagenesis that Renders Functional Inadequacies in Host Plants
  191. Preparation of monodisperse aqueous microspheres containing high concentration ofl-ascorbic acid by microchannel emulsification
  192. Formulation of monodisperse oil‐in‐water emulsions loaded with ergocalciferol and cholecalciferol by microchannel emulsification: insights of production characteristics and stability
  193. Garlic (Allium sativum): diet based therapy of 21st century–a review
  194. Formulation characteristics of triacylglycerol oil-in-water emulsions loaded with ergocalciferol using microchannel emulsification
  195. Formulation of monodisperse water-in-oil emulsions encapsulating calcium ascorbate and ascorbic acid 2-glucoside by microchannel emulsification
  196. Monodisperse W/O/W emulsions encapsulating l-ascorbic acid: Insights on their formulation using microchannel emulsification and stability studies
  197. Identification and characterization of rhizospheric microbial diversity by 16S ribosomal RNA gene sequencing
  198. Onion: Nature Protection Against Physiological Threats
  199. Molecular identification and characterization of Pseudomonas sp. NCCP-407 for phenol degradation isolated from industrial waste
  200. Bioinformatics based structural characterization of glucose dehydrogenase (gdh) gene and growth promoting activity of Leclercia sp. QAU-66
  201. Comparison of antimicrobial activity, phytochemical profile and minerals composition of garlic Allium sativum and Allium tuberosum
  202. Mechanisms Involved in the Therapeutic Effects of Soybean (Glycine Max)
  203. Physicochemical Characteristics, Functional Properties, and Nutritional Benefits of Peanut Oil: A Review
  204. A Question Mark on Iron Deficiency in 185 Million People of Pakistan: Its Outcomes and Prevention
  205. Physicochemical Characteristics, Nutritional Properties, and Health Benefits of Argan Oil: A Review
  206. Erratum to: Sphingobacterium pakistanensis sp. nov., a novel plant growth promoting rhizobacteria isolated from rhizosphere of Vigna mungo
  207. A Question Mark on Zinc Deficiency in 185 Million People in Pakistan—Possible Way Out
  208. Xylanolytic modification in wheat flour and its effect on dough rheological characteristics and bread quality attributes
  209. Sphingobacterium pakistanensis sp. nov., a novel plant growth promoting rhizobacteria isolated from rhizosphere of Vigna mungo
  210. Mineral Composition and Health Functionality of Zamzam Water: A Review
  211. Industrial lab-on-a-chip: Design, applications and scale-up for drug discovery and delivery
  212. Preparation and Characterization of Water-in-Oil-in-Water Emulsions Containing a High Concentration ofL-Ascorbic Acid
  213. Preparation and characterization of water-in-oil emulsions loaded with high concentration of l-ascorbic acid
  214. Phytochemicals and biofunctional properties of buckwheat: a review
  215. Effects of Hydrocolloids on Partial Baking and Frozen Storage of Wheat Flour Chapatti
  216. Genotoxicity evaluation of chlorpyrifos: a gender related approach in regular toxicity testing
  217. Selection and characterization of probiotic culture ofStreptococcus thermophilusfromdahi
  218. In vitro comparative study of Bougainvillea spectabilis “stand” leaves and Bougainvillea variegata leaves in terms of phytochemicals and antimicrobial activity
  219. Nutritional and functional evaluation of wheat flour cookies supplemented with gram flour
  220. Effect of flour processing on the quality characteristics of a soy-based beverage
  221. Antibacterial activity of the venom of Heterometrus xanthopus