What is atherosclerosis. How does it develop. What are the risk factors for atherosclerosis. How is atherosclerosis diagnosed. What are the treatment options for atherosclerosis. Can lifestyle changes help prevent or manage atherosclerosis. What complications can arise from untreated atherosclerosis.

The Nature of Atherosclerosis: A Stealthy Arterial Condition

Atherosclerosis, often referred to as “hardening of the arteries,” is a common cardiovascular disorder that develops gradually over time. This condition occurs when fatty deposits, cholesterol, and other substances accumulate in the arterial walls, forming plaques. As these plaques grow, they can narrow or completely obstruct arteries, leading to a range of health complications throughout the body.

The insidious nature of atherosclerosis lies in its silent progression. Symptoms often do not manifest until blood flow to certain parts of the body becomes significantly impaired. This characteristic makes atherosclerosis particularly dangerous, as it can advance undetected for years before causing noticeable health issues.

The Process of Arterial Hardening

How exactly does atherosclerosis develop? The process begins with damage to the inner lining of arteries, which can be caused by various factors such as high blood pressure, smoking, or high cholesterol levels. This damage allows LDL cholesterol (often called “bad” cholesterol) to penetrate the arterial wall. The body’s immune system responds by sending white blood cells to the area, which absorb the cholesterol, creating foam cells that accumulate and form fatty streaks.

Over time, these fatty streaks evolve into more complex plaques, incorporating smooth muscle cells, calcium, and other substances. As plaques grow, they narrow the artery’s lumen (the space through which blood flows), reducing blood flow and oxygen supply to tissues and organs.

Risk Factors: Identifying the Culprits Behind Atherosclerosis

Understanding the risk factors for atherosclerosis is crucial for both prevention and management of the condition. While some risk factors are beyond our control, many are lifestyle-related and can be modified.

Non-Modifiable Risk Factors

• Age: The risk of atherosclerosis increases as we get older
• Gender: Men are generally at higher risk than pre-menopausal women
• Family history: Genetic predisposition can play a significant role

Modifiable Risk Factors

• High blood cholesterol levels
• High blood pressure (hypertension)
• Smoking
• Obesity or being overweight
• Physical inactivity
• Diabetes
• Poor diet high in saturated and trans fats

By addressing these modifiable risk factors, individuals can significantly reduce their likelihood of developing or worsening atherosclerosis.

Diagnosis: Detecting the Silent Progression of Atherosclerosis

Given the asymptomatic nature of atherosclerosis in its early stages, how do healthcare providers diagnose this condition? Diagnosis typically involves a combination of physical examination, medical history review, and various diagnostic tests.

Physical Examination and Medical History

During a physical exam, a healthcare provider may listen to the heart and lungs with a stethoscope. Atherosclerosis can create a distinctive whooshing or blowing sound, known as a “bruit,” over an affected artery. The provider will also review the patient’s medical history and assess risk factors.

Blood Tests

Blood tests are crucial for assessing cholesterol levels and other cardiovascular risk factors. These tests typically measure:

• Total cholesterol
• LDL cholesterol
• HDL cholesterol
• Triglycerides
• Blood glucose levels

Imaging Tests

Various imaging techniques can provide detailed information about the condition of arteries and blood flow. These may include:

• Doppler ultrasound
• Magnetic Resonance Arteriography (MRA)
• CT angiography
• Arteriograms or angiography

These tests allow healthcare providers to visualize the extent of plaque buildup and identify areas of narrowing or blockage in the arteries.

Treatment Approaches: Combating Atherosclerosis

How is atherosclerosis treated once diagnosed? Treatment strategies typically involve a combination of lifestyle modifications and medical interventions, tailored to the individual’s specific condition and risk factors.

Lifestyle Modifications

Lifestyle changes are the cornerstone of atherosclerosis treatment and prevention. These include:

• Adopting a heart-healthy diet low in saturated and trans fats
• Increasing physical activity
• Quitting smoking
• Maintaining a healthy weight
• Managing stress
• Limiting alcohol consumption

Medications

Various medications may be prescribed to manage atherosclerosis and its risk factors:

• Statins to lower cholesterol levels
• Antihypertensive drugs to control blood pressure
• Antiplatelet medications (like aspirin) to prevent blood clots
• Drugs to manage diabetes, if present

Surgical Interventions

In severe cases or when significant blockages are present, surgical procedures may be necessary:

• Angioplasty and stent placement to open narrowed arteries
• Coronary artery bypass grafting (CABG) for severely blocked coronary arteries
• Carotid endarterectomy to remove plaque from carotid arteries

Prevention Strategies: Safeguarding Arterial Health

Can atherosclerosis be prevented? While it’s not always possible to prevent atherosclerosis entirely, especially in cases with genetic predisposition, many effective strategies can significantly reduce the risk of developing or worsening the condition.

Dietary Considerations

A heart-healthy diet is crucial in preventing atherosclerosis. Key dietary recommendations include:

• Increasing consumption of fruits, vegetables, and whole grains
• Choosing lean proteins, such as fish, poultry, and plant-based sources
• Limiting intake of saturated and trans fats
• Reducing sodium consumption
• Incorporating omega-3 fatty acids, found in fatty fish and certain plant oils

Regular Physical Activity

Exercise plays a vital role in maintaining cardiovascular health. The American Heart Association recommends:

• At least 150 minutes of moderate-intensity aerobic activity or 75 minutes of vigorous-intensity aerobic activity per week
• Muscle-strengthening activities at least two days per week

Stress Management

Chronic stress can contribute to atherosclerosis development. Effective stress management techniques include:

• Meditation and mindfulness practices
• Regular exercise
• Adequate sleep
• Time management and prioritization
• Seeking support from friends, family, or mental health professionals when needed

Complications: The Far-Reaching Effects of Atherosclerosis

What complications can arise from untreated atherosclerosis? The consequences of advanced atherosclerosis can be severe and life-threatening. Understanding these potential complications underscores the importance of early detection and management.

Cardiovascular Complications

• Coronary Artery Disease (CAD): Narrowing of the arteries supplying the heart, which can lead to angina or heart attack
• Heart Failure: When the heart can’t pump blood effectively due to damaged heart muscle
• Arrhythmias: Irregular heartbeats that can result from damage to the heart’s electrical system

Cerebrovascular Complications

• Stroke: Blockage of blood flow to the brain, causing damage to brain tissue
• Transient Ischemic Attack (TIA): A temporary interruption of blood flow to the brain, often a warning sign of an impending stroke

Peripheral Artery Disease (PAD)

Atherosclerosis affecting arteries in the limbs can lead to:

• Claudication: Pain or cramping in the legs during physical activity
• Critical limb ischemia: Severe blockage that can cause tissue death and potentially require amputation

Aneurysms

Weakening of arterial walls due to atherosclerosis can lead to aneurysms, which are bulges in the artery that can rupture and cause life-threatening bleeding.

Living with Atherosclerosis: Strategies for Long-Term Management

For individuals diagnosed with atherosclerosis, how can they effectively manage their condition and maintain a good quality of life? Living with atherosclerosis requires a commitment to ongoing health management and lifestyle modifications.

Regular Medical Check-ups

Consistent monitoring of cardiovascular health is essential. This includes:

• Regular blood pressure checks
• Periodic cholesterol tests
• Monitoring of other risk factors such as blood glucose levels
• Follow-up imaging tests as recommended by healthcare providers

Medication Adherence

For those prescribed medications to manage atherosclerosis or its risk factors, strict adherence to the prescribed regimen is crucial. This may include:

• Taking medications as directed
• Understanding potential side effects and when to report them
• Regular review of medications with healthcare providers to ensure optimal management

Lifestyle Maintenance

Sustaining healthy lifestyle changes is key to managing atherosclerosis long-term. This involves:

• Consistent adherence to a heart-healthy diet
• Maintaining regular physical activity
• Stress management techniques
• Avoiding tobacco use and excessive alcohol consumption
• Weight management

Support Systems

Living with a chronic condition like atherosclerosis can be challenging. Establishing strong support systems can be beneficial:

• Joining support groups for individuals with cardiovascular conditions
• Engaging family and friends in health goals
• Seeking counseling or therapy if needed to address emotional aspects of living with a chronic condition

Emerging Research: New Frontiers in Atherosclerosis Treatment

What new developments are on the horizon for atherosclerosis treatment and prevention? The field of cardiovascular medicine is constantly evolving, with researchers exploring innovative approaches to combat atherosclerosis more effectively.

Targeted Therapies

Scientists are investigating therapies that target specific molecular pathways involved in atherosclerosis development:

• PCSK9 inhibitors: A new class of drugs that dramatically lower LDL cholesterol levels
• Anti-inflammatory therapies: Targeting inflammation in the arterial walls to prevent plaque formation
• Gene therapies: Exploring ways to modify genes associated with atherosclerosis risk

Advanced Imaging Techniques

New imaging technologies are being developed to detect atherosclerosis at earlier stages and monitor treatment effectiveness more accurately:

• Intravascular ultrasound (IVUS) with virtual histology
• Optical coherence tomography (OCT)
• Positron emission tomography (PET) with specialized tracers

Personalized Medicine Approaches

The future of atherosclerosis management may lie in personalized treatment plans based on an individual’s genetic profile and specific risk factors:

• Genetic testing to identify high-risk individuals
• Tailored medication regimens based on genetic markers
• Personalized lifestyle interventions guided by genetic and metabolic profiles

As research progresses, these emerging approaches hold promise for more effective prevention, earlier detection, and more targeted treatment of atherosclerosis, potentially reducing its impact on global health.

In conclusion, atherosclerosis remains a significant health challenge, but with ongoing research, improved diagnostic tools, and a growing understanding of its mechanisms, the future looks promising for better management and prevention of this pervasive condition. By staying informed about the latest developments and maintaining a proactive approach to cardiovascular health, individuals can take significant steps towards protecting their arterial health and overall well-being.

Atherosclerosis: MedlinePlus Medical Encyclopedia

Atherosclerosis, sometimes called “hardening of the arteries,” occurs when fat, cholesterol, and other substances build up in the walls of arteries. These deposits are called plaques. Over time, these plaques can narrow or completely block the arteries and cause problems throughout the body.

Atherosclerosis is a common disorder.

Watch this video about:Atherosclerosis

Atherosclerosis often occurs with aging. As you grow older, plaque buildup narrows your arteries and makes them stiffer. These changes make it harder for blood to flow through them.

Clots may form in these narrowed arteries and block blood flow. Pieces of plaque can also break off and move to smaller blood vessels, blocking them.

These blockages starve tissues of blood and oxygen. This can result in damage or tissue death. It is a common cause of heart attack and stroke.

High blood cholesterol levels can cause hardening of the arteries at a younger age.

For many people, high cholesterol levels are due to a diet that is too high in saturated fats and trans fats.

Other factors that can contribute to hardening of the arteries include:

• Diabetes
• Family history of hardening of the arteries
• High blood pressure
• Lack of exercise
• Being overweight or obese
• Smoking

Atherosclerosis does not cause symptoms until blood flow to part of the body becomes slowed or blocked.

If the arteries supplying the heart become narrow, blood flow can slow down or stop. This can cause chest pain (stable angina), shortness of breath, and other symptoms.

Narrowed or blocked arteries may also cause problems in the intestines, kidneys, legs, and brain.

A health care provider will perform a physical exam and listen to the heart and lungs with a stethoscope. Atherosclerosis can create a whooshing or blowing sound (“bruit”) over an artery.

All adults over the age of 18 should have their blood pressure checked every year. More frequent measurement may be needed for those with a history of high blood pressure readings or those with risk factors for high blood pressure.

Cholesterol testing is recommended in all adults. The major national guidelines differ on the suggested age to start testing.

• Screening should begin between ages 20 to 35 for men and ages 20 to 45 for women.
• Repeat testing is not needed for five years for most adults with normal cholesterol levels.
• Repeat testing may be needed if lifestyle changes occur, such as large increase in weight or a change in diet.
• More frequent testing is needed for adults with a history of high cholesterol, diabetes, kidney problems, heart disease, stroke, and other conditions

A number of imaging tests may be used to see how well blood moves through your arteries.

• Doppler tests that use ultrasound or sound waves
• Magnetic resonance arteriography (MRA), a special type of MRI scan
• Special CT scans called CT angiography
• Arteriograms or angiography that use x-rays and contrast material (sometimes called “dye”) to see the path of blood flow inside the arteries

Lifestyle changes will reduce your risk for atherosclerosis. Things you can do include:

• Quit smoking: This is the single most important change you can make to reduce your risk for heart disease and stroke.
• Avoid fatty foods: Eat well-balanced meals that are low in fat and cholesterol. Include several daily servings of fruits and vegetables. Adding fish to your diet at least twice a week may be helpful. However, do not eat fried fish.
• Limit how much alcohol you drink: Recommended limits are one drink a day for women, two a day for men.
• Get regular physical activity: Exercise with moderate intensity (such as brisk walking) 5 days a week for 30 minutes a day if you are at a healthy weight. For weight loss, exercise for 60 to 90 minutes a day. Talk to your provider before starting a new exercise plan, especially if you have been diagnosed with heart disease or you have ever had a heart attack.

If your blood pressure is high, it is important for you to lower it and keep it under control.

The goal of treatment is to reduce your blood pressure so that you have a lower risk of health problems caused by high blood pressure. You and your provider should set a blood pressure goal for you.

• Do not stop or change high blood pressure medicines without talking to your provider.

Your provider may want you to take medicine for abnormal cholesterol levels or for high blood pressure if lifestyle changes do not work. This will depend on:

• Your age
• The medicines you take
• Your risk of side effects from possible medicines
• Whether you have heart disease or other blood flow problems
• Whether you smoke or are overweight
• Whether you have diabetes or other heart disease risk factors
• Whether you have any other medical problems, such as kidney disease

Your provider may suggest taking aspirin or another medicine to help prevent blood clots from forming in your arteries. These medicines are called antiplatelet drugs. DO NOT take aspirin without first talking to your provider.

Losing weight if you are overweight and reducing blood sugar if you have diabetes or pre-diabetes can help reduce the risk of developing atherosclerosis.

Atherosclerosis cannot be reversed once it has occurred. However, lifestyle changes and treating high cholesterol levels can prevent or slow the process from becoming worse. This can help reduce the chances of having a heart attack and stroke as a result of atherosclerosis.

In some cases, the plaque is part of a process that causes a weakening of the wall of an artery. This can lead to a bulge in an artery called an aneurysm. Aneurysms can break open (rupture). This causes bleeding that can be life threatening.

Hardening of the arteries; Arteriosclerosis; Plaque buildup – arteries; Hyperlipidemia – atherosclerosis; Cholesterol – atherosclerosis

• Abdominal aortic aneurysm repair – open – discharge
• Aortic aneurysm repair – endovascular – discharge
• Aspirin and heart disease
• Heart failure – discharge
• Heart failure – what to ask your doctor
• High blood pressure – what to ask your doctor
• Type 2 diabetes – what to ask your doctor

• Atherosclerosis
• Carotid stenosis – X-ray of the left artery
• Carotid stenosis – X-ray of the right artery
• Enlarged view of atherosclerosis
• Prevention of heart disease
• Developmental process of atherosclerosis

Arnett DK, Blumenthal RS, Albert MA, Buroker AB, et al. 2019 ACC/AHA Guideline on the primary prevention of cardiovascular disease: executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. J Am Coll Cardiol. 2019;74(10):1376-1414. PMID: 30894319 pubmed.ncbi.nlm.nih.gov/30894319/.

Genest J, Mora S, Libby P. Lipoprotein disorders and cardiovascular disease. In: Libby P, Bonow RO, Mann DL, Tomaselli GF, Bhatt DL, Solomon SD, eds. Braunwald’s Heart Disease: A Textbook of Cardiovascular Medicine. 12th ed. Philadelphia, PA: Elsevier; 2022:chap 27.

Libby P. The vascular biology of atherosclerosis. In: Libby P, Bonow RO, Mann DL, Tomaselli GF, Bhatt DL, Solomon SD, eds. Braunwald’s Heart Disease: A Textbook of Cardiovascular Medicine. 12th ed. Philadelphia, PA: Elsevier; 2022: chap 24.

Marks AR. Cardiac and circulatory function. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 47.

US Preventive Services Task Force website. Final recommendation statement: statin use for the primary prevention of cardiovascular disease in adults: preventive medication. Updated November 13, 2016. Accessed April 5, 2022. www.uspreventiveservicestaskforce.org/Page/Document/RecommendationStatementFinal/statin-use-in-adults-preventive-medication1.

Whelton PK, Carey RM, Aronow WS, et al. 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA guideline for the prevention, detection, evaluation, and management of high blood pressure in adults: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. J Am Coll Cardiol. 2018;71(19):2199-2269. PMID: 2914653 pubmed.ncbi.nlm.nih.gov/29146533/.

Updated by: Michael A. Chen, MD, PhD, Associate Professor of Medicine, Division of Cardiology, Harborview Medical Center, University of Washington Medical School, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A. D.A.M. Editorial team.

What Is Scleroderma? Symptoms & Causes| NIAMS

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• Overview, Symptoms, & Causes

• Diagnosis, Treatment, & Steps to Take

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Overview of Scleroderma

Scleroderma is an autoimmune connective tissue and rheumatic disease that causes inflammation in the skin and other areas of the body. When an immune response tricks tissues into thinking they are injured, it causes inflammation, and the body makes too much collagen, leading to scleroderma. Too much collagen in your skin and other tissues causes patches of tight, hard skin. Scleroderma involves many systems in your body. The following definitions can help you better understand how the disease affects each of those systems.

• A connective tissue disease is one that affects tissues such as skin, tendons, and cartilage. Connective tissue supports, protects, and provides structure to other tissues and organs.
• Autoimmune diseases happen when the immune system, which normally helps protect the body from infection and disease, attacks its own tissues.
• Rheumatic disease refers to a group of conditions characterized by inflammation or pain in the muscles, joints, or fibrous tissue.

There are two major types of scleroderma:

• Localized scleroderma only affects the skin and the structures directly under the skin.
• Systemic scleroderma, also called systemic sclerosis, affects many systems in the body. This is the more serious type of scleroderma and can damage your blood vessels and internal organs, such as the heart, lungs, and kidneys.

There is no cure for scleroderma. The goal of treatment is to relieve symptoms and stop the progression of the disease. Early diagnosis and ongoing monitoring are important.

What happens in scleroderma?

The cause of scleroderma is unknown. However, researchers think that the immune system overreacts and causes inflammation and injury to the cells that line blood vessels. This triggers connective tissue cells, especially a cell type called fibroblasts, to make too much collagen and other proteins. The fibroblasts live longer than normal, causing a buildup of collagen in the skin and other organs, leading to the signs and symptoms of scleroderma.

Who Gets Scleroderma?

Anyone can get scleroderma; however, some groups have a higher risk of developing the disease. The following factors may affect your risk.

• Sex. Scleroderma is more common in women than in men.
• Age. The disease usually appears between the ages of 30 and 50 and is more common in adults than children.
• Race. Scleroderma can affect people of all races and ethnic groups, but the disease can affect African Americans more severely. For example: 
  • The disease is more common in African Americans than European Americans.
  • African Americans with scleroderma develop the disease earlier when compared with other groups.
  • African Americans are more likely to have more skin involvement and lung disease when compared with other groups.

Types of Scleroderma

• Localized scleroderma affects the skin and underlying tissues and generally appears in one or both of these patterns:
  • Morphea, or patches of scleroderma that may be a half-inch or larger in diameter.
  • Linear scleroderma, when the scleroderma thickening occurs in a line. This usually extends down an arm or leg, but sometimes runs down the forehead and face.
• Systemic scleroderma, sometimes called systemic sclerosis, affects your skin, tissues, blood vessels, and major organs. Doctors usually divide systemic scleroderma into two types:
  • Limited cutaneous scleroderma, which comes on gradually and affects the skin on your fingers, hands, face, lower arms, and legs below the knees.
  • Diffuse cutaneous scleroderma, which comes on more rapidly and starts as being limited to the fingers and toes, but then extends beyond the elbows and knees to the upper arms, trunk, and thighs. This type usually has more internal organ damage.  

Symptoms of Scleroderma

The symptoms of scleroderma vary from person to person depending on the type of scleroderma you have.

Localized scleroderma typically causes patches of thick, hard skin in one of two patterns.

• Morphea causes patches of skin to thicken into firm, oval-shaped areas. These areas may have a yellow, waxy appearance surrounded by a reddish or bruise-like edge. The patches may stay in one area or spread to other areas of skin. The disease usually becomes inactive after over time, but you may still have darkened patches of skin. Some people also develop fatigue (feeling tired).
• Linear scleroderma causes lines of thickened or different colored skin to run down your arm, leg, and, rarely, on the forehead.

Systemic scleroderma, also known as systemic sclerosis, may come on quickly or gradually and may also cause problems with your internal organs in addition to the skin. Many people with this type of scleroderma have fatigue.

• Limited cutaneous scleroderma comes on gradually and usually affects skin on your fingers, hands, face, lower arms, and legs below the knees. It can also cause problems with your blood vessels and esophagus. The limited form has internal organ involvement, but it is generally milder than in the diffuse form. People with limited cutaneous scleroderma often have all or some of the symptoms that some doctors call CREST, which stands for the following symptoms:
  • Calcinosis, the formation of calcium deposits in the connective tissues, which can be detected by x-ray.
  • Raynaud’s phenomenon, a condition in which the small blood vessels of the hands or feet contract in response to cold or anxiety, causing color changes in fingers and toes (white, blue, and/or red).
  • Esophageal dysfunction, which refers to the impaired function of the esophagus (the tube connecting the throat and the stomach) that occurs when smooth muscles in the esophagus lose normal movement.
  • Sclerodactyly, which is thick and tight skin on the fingers, resulting from deposits of excess collagen within skin layers.
  • Telangiectasia, a condition caused by the swelling of tiny blood vessels, in which small red spots appear on the hands and face.
• Diffuse cutaneous scleroderma comes on suddenly, usually with skin thickening on your fingers or toes. The skin thickening then spreads to the rest of your body above the elbows and/or knees. This type can damage your internal organs, such as:
  • Anywhere along your digestive system.
  • Your lungs.
  • Your kidneys.
  • Your heart.

Although CREST historically refers to the limited scleroderma, people with the diffuse form of scleroderma can also have CREST features.

Causes of Scleroderma

Researchers do not know the exact cause of scleroderma, but they suspect that several factors may contribute to the disease:

• Genetic makeup. Genes can increase the chance for certain people to develop scleroderma and play a role determining the type of scleroderma they have. You cannot inherit the disease, and it is not passed from parent to child like some genetic diseases. However, first-degree relatives of people with scleroderma are at higher risk of developing scleroderma than the general population.
• Environment. Researchers suspect that exposure to some environmental factors, such as viruses or chemicals, may trigger scleroderma.
• Immune system changes. Abnormal immune or inflammatory activity in your body triggers cell changes that cause the production of too much collagen.
• Hormones. Women develop most types of scleroderma more often than men. Researchers suspect that hormonal differences between women and men might play a part in the disease.

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SOLIDIFICATION POINT | Encyclopedia Krugosvet

SOLIDIFICATION POINT (solidification point) is the temperature at which a liquid turns into a solid.

For a pure substance, it coincides with its melting point, i.e. transition temperature from solid to liquid. Only pure crystalline substances have a strictly defined solidification temperature.

Amorphous, i.e. non-crystalline substances (for example, glass, butter) solidify (and melt) in a certain temperature range. For such substances, a distinction is made between the solidification and melting temperatures: the solidification temperature is understood as the temperature at which the first signs of a solid phase appear in the system upon cooling or the last traces of it disappear upon heating, and the melting point is the lowest temperature at which the solid phase disappears during cooling. the last traces of the liquid phase or when heated, the first signs of it appear. The solidification point of most substances changes slightly with pressure: as a rule, it rises with increasing pressure.

Mixtures of liquids, such as water and alcohols, also solidify (freeze) over a wide range of temperatures, and their freezing point is always lower than that of the pure component with a higher freezing point. Therefore, ethyl alcohol (freezing point -130 ° C) and ethylene glycol (freezing point -25 ° C) are widely used as one of the components of antifreeze in the cooling system of automobiles.

The temperature at which the last traces of a liquid mixture freezes can be much lower than the component with a lower freezing point.

Some substances, such as iodine and paradichlorobenzene, pass from a solid state immediately into a gaseous state (sublimate). They have neither a melting point nor a solidification point.

Under certain conditions, liquids can be cooled below their true solidification temperature without solidification. Such liquids are called supercooled. Since a solid cannot be “overheated” so that it does not become a liquid, the melting and solidification temperatures are usually determined experimentally from the melt. This avoids the error due to liquid subcooling. For the same reasons, in the scientific and technical literature, when describing the physical properties of a substance, the term “melting point” is preferred. See also BOILING POINT; HEAT; LIQUID THEORY.

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1.2.1.0012.15 Solidification temperature – Pharmacopoeia.rf

Contents

The solidification temperature is the temperature at which a substance changes from a liquid to a solid state upon cooling. Two methods are used to determine the solidification temperature.

MINISTRY OF HEALTH OF THE RUSSIAN FEDERATION OFS.1.2.1.0012.15
Instead of GF XII , part 1, OFS 42-0035-07

The solidification temperature is the temperature at which a substance changes from a liquid to a solid state upon cooling. Two methods are used to determine the solidification temperature.

Procedure 1

Place a sufficient amount (about 10 g) of the test substance in the liquid state into the dry inner test tube of instrument 1 (Fig. 1) (the solid is preliminarily melted at a temperature not exceeding 20 °C of the expected solidification temperature) and strengthened so that the mercury ball was in the middle of the layer of the test substance. Then the inner tube with the test substance is placed in the outer tube and, with rapid cooling, the approximate solidification temperature is determined. After that, the outer tube, together with the inner tube, is placed in a water bath at a temperature of 5 °C above the approximately determined solidification temperature until the test substance is completely melted. Then fill the beaker with water or saturated sodium chloride solution at a temperature 5 °C below the expected solidification temperature. Place the outer tube together with the inner tube in a beaker. With constant stirring of the test substance, note the temperature every 30 s. Initially, there is a gradual decrease in temperature, then when a solid phase appears, it remains constant for a while or rises before becoming constant (at this point, stirring is stopped), and then falls again. The highest temperature is noted, which remains constant for a short time during the transition of a substance from a liquid to a solid state. This temperature is taken as the solidification temperature.

If the substance remains liquid at the expected solidification temperature, cool it 1 to 2 °C below the expected solidification temperature and induce solidification by introducing small amounts (several crystals) of the substance to be tested or by rubbing the walls of the inner tube with a thermometer.

Dimensions in mm

fig.1 a test tube with an inner diameter of about 25 mm and a length of about 150 mm, placed inside another test tube with a diameter of about 40 mm and a length of about 160 mm. The inner test tube is closed with a stopper equipped with a thermometer about 175 mm long with a division value of 0.2 °C, which is fixed in such a way that the mercury ball is located at a distance of about 15 mm from the bottom of the test tube. The inner tube has a hole through which passes a stirrer shaft made of a glass rod or other suitable material, bent at the end at a right angle in the form of a loop, the outer diameter of which is about 18 mm. The inner tube, together with the outer tube, is placed in the center of a 1 L beaker containing a suitable coolant, the level of which is about 20 mm apart. The cooling bath should also be equipped with a thermometer.

Method 2

For solids with a high solidification point between +30 and +100 °C (paraffins and high-melting crystalline solids).

The test substance, melted in a water bath or in a thermostat at a temperature of 15 – 20 °C above the expected solidification temperature, is thoroughly mixed and poured into a heated apparatus 2 (Fig. 2) to ¾ of its height. The temperature of the test substance after being placed in the instrument shall exceed the expected solidification temperature by at least 8 °C. A thermometer is inserted into the hole of the device on a cork along the axis of the device so that the mercury ball of the thermometer is approximately at half the height of the layer of molten substance. Leave the device until the temperature reaches 3 – 4 °C above the solidification temperature.