APC Science Union · Online Library

Author: Polar Glacier Reviewer: Weiming   Note: This is a long article, and some readers may find parts of it difficult. It offers a substantial treatment of the subject and is recommended for students, enthusiasts, and readers in related fields. I. Common equations in chemical kinetics   Before discussing enzyme kinetics, let us review several common cases in chemical reaction kinetics. 1. First-order reactions   A first-order reaction is one whose rate is proportional to the first power of the reactant concentration.   The reaction is shown below:   Its rate equation can therefore be written as:   From the definition of a first-order reaction:   Therefore:   Rearranging:   Solving gives: 2. Second-order reactions   In a second-order reaction, the reaction rate is proportional ...

Author: Self-Control Reviewers: Guanfu · Juntian   Eighteenth-century Europe was an age of extraordinary growth. In one short century, European society seemed to release all the energy accumulated through a thousand years of the Middle Ages. Oceanic exploration brought immense wealth and opportunity, religious reform liberated thought, and scientific progress transformed society. Meanwhile, the last of the classical era’s three great financial bubbles was slowly taking shape, nourished by this wider environment and preparing to inflict another heavy blow.   In the eighteenth century, Britain defeated the Netherlands in commerce and competed with powers such as France and Spain for overseas colonies. At home, the Glorious Revolution had brought an institutional transition from monarchica ...

Author: 阿白特尔   In years of intense solar activity, point a telescope fitted with a Baader solar filter at the Sun—never look directly at the Sun through an unfiltered telescope or with the naked eye—and you may notice that the Sun’s “skin” is not in the best condition. Clusters of dark patches often appear across its bright surface. These, of course, are the familiar sunspots. Yet the specialists who know the Sun’s skin ailments best—solar physicists—pay even closer attention to another kind of dark structure above its surface. This is our subject today: the solar filament.   Some readers may wonder: “I have observed the Sun through a Baader-filtered telescope for years. Why have I seen only sunspots, and never the ‘solar filaments’ you describe?” If you have watched the edge of the sola ...

Author: Shenzhou Reviewer: Weiming   Blood is a fluid tissue that circulates through the human cardiovascular system. Its chief role is to transport substances, and it consists mainly of plasma, blood cells, and platelets. Red and white blood cells are crucial to transport and defense against foreign invaders, respectively. Platelets are cell fragments produced by megakaryocytes in the bone marrow and are essential for hemostasis. This article introduces the metabolic features of these three cellular components. Red blood cell metabolism   Red blood cells are among the most important cells in the blood. They arise in the bone marrow through the committed differentiation of hematopoietic stem cells, passing through the proerythroblast, early erythroblast, intermediate erythroblast, late ...

Author: Shiguang (Yixian Studio) Reviewed by: Baiyan   A game called Merge Watermelon recently swept through Qzone. After getting hooked, players jokingly began calling themselves “watermelon people.” Memes, parody images, and Watermelon bots soon followed, along with spin-offs such as Liver-Saving Merge Watermelon, Merge Tiny Grapes, and Merge a Great Nation… This article looks at how to build a Merge Watermelon game in Unity. Step 1: Gathering assets   The assets, or textures, determine what the fruit looks like. Replace them with other elements—say, breasts (ahem), Polandballs, or something similar—and you can make parody versions such as Merge a Great Nation.   To keep things simple (actually, because I cannot draw), I drew a few balls to represent the fruit:   From left to right, ...

Author: Shiguang Reviewed by: Yuandao Preface   This article records some of my thinking and development work while I was building a simple 2D side-scrolling platformer for an assessment at my university’s studio (yes, really). If game development interests you and you would like to become a developer, it may offer some useful pointers. If you already develop games, you are welcome to get in touch and compare notes 😄! Choosing an engine   When you decide to make a game, the first consideration is the game engine. In other words: which engine should I use? Two mainstream choices are Unity and Unreal Engine 4 (UE4), each with its own strengths and weaknesses. Unity’s 3D rendering, for example, is not as strong as UE4’s, but Unity offers many plug-ins that can make development more effic ...

Author: Self-Control Reviewers: Guanfu · Juntian   Correction: In the previous installment, we said that John Law solved the government’s long-standing debt problem once he had replaced metallic money with paper currency. That was not in fact the case. His measures only eased the pressure of government debt to some extent, and we have corrected this point in the article below.   In the previous installment, we described how John Law replaced metallic money with paper currency and strictly controlled the bank’s reserves to preserve confidence in it. He promoted paper currency through tax measures, successfully revitalizing the French economy. Paper money’s portability and low transaction costs also helped the economy grow rapidly. As his second step, Law established the Mississippi Compan ...

Author: Shenzhou Reviewer: Shiye   The faithful inheritance of DNA is essential to the relative stability of a species. Yet factors inside and outside the body act on DNA continuously, making changes to an organism’s DNA unavoidable. The balance between fidelity and change maintains species stability while providing the basis for evolution and the diversity of life.   DNA damage takes many forms, including base loss, damage to base structure, pyrimidine-dimer formation, single- and double-strand breaks, and DNA cross-linking. Damage to Base Structure   Damage to bases and sugar groups is caused mainly by nitrous-acid-induced base deamination and the oxidative modification of DNA bases, including pyrimidines, by oxidizing agents. Bases containing amino groups can also undergo deaminatio ...

Author: Saito Shin Reviewed by: Yuandao   At 4:30 a.m. Beijing time on November 24, 2020, the Long March 5 Y5 launch vehicle successfully lifted off from the Wenchang Spacecraft Launch Site in Hainan carrying the Chang’e 5 probe. CCTV News and the Our Space new-media platform jointly broadcast the entire launch live, demonstrating the confidence of China’s space program in the mission. This time, let us talk about Chang’e 5.   Many readers may be wondering: what are the technical challenges of the Chang’e 5 mission?   We will look at them separately, before and after launch. Before Launch:   For the prelaunch phase, consider just one example: propellant loading. Chang’e 5 was fueled in its combined-spacecraft configuration. The complete vehicle contains more than 600 units or sets in ...

Author: Sirius King Proofreader: Millisecond Biology consultant and reviewer: Kuicao   What kind of achievement makes someone successful? Some say becoming a billionaire or the world’s richest person; others say being known everywhere. Then what makes someone immortal? Some say a name in the history books; others, a monument and a biography. One man was poor, ill, and little known during his lifetime, and rose in social rank only in his later years. Today his portrait appears on Swedish banknotes, his statues stand on university campuses, biologists revere him, and his country commemorates him. He was the Swedish naturalist, father of modern biological taxonomy, pioneer of binomial nomenclature, and “Prince of Flowers”: Carl von Linnaeus. A Swedish banknote Portrait of Carl von Linnaeu ...