TY  - CHAP
A1  - Akimbekov, Nuraly S.
A1  - Digel, Ilya
A1  - Sherelkhan, Dinara K.
A1  - Razzaque, Mohammed S.
T1  - Vitamin D and Phosphate Interactions in Health and Disease
T2  - Phosphate Metabolism
N2  - Vitamin D plays an essential role in calcium and inorganic phosphate (Pi) homeostasis, maintaining their optimal levels to assure adequate bone mineralization. Vitamin D, as calcitriol (1,25(OH)2D), not only increases intestinal calcium and phosphate absorption but also facilitates their renal reabsorption, leading to elevated serum calcium and phosphate levels. The interaction of 1,25(OH)2D with its receptor (VDR) increases the efficiency of intestinal absorption of calcium to 30–40% and phosphate to nearly 80%. Serum phosphate levels can also influence 1,25 (OH)2D and fibroblast growth factor 23 (FGF23) levels, i.e., higher phosphate concentrations suppress vitamin D activation and stimulate parathyroid hormone (PTH) release, while a high FGF23 serum level leads to reduced vitamin D synthesis. In the vitamin D-deficient state, the intestinal calcium absorption decreases and the secretion of PTH increases, which in turn causes the stimulation of 1,25(OH)2D production, resulting in excessive urinary phosphate loss. Maintenance of phosphate homeostasis is essential as hyperphosphatemia is a risk factor of cardiovascular calcification, chronic kidney diseases (CKD), and premature aging, while hypophosphatemia is usually associated with rickets and osteomalacia. This chapter elaborates on the possible interactions between vitamin D and phosphate in health and disease.
KW  - Vitamin D
KW  - PTH
KW  - Phosphate
KW  - FGF23
KW  - Klotho
Y1  - 2022
SN  - 978-3-030-91621-3
U6  - https://doi.org/10.1007/978-3-030-91623-7_5
SP  - 37
EP  - 46
PB  - Springer
CY  - Cham
ER  - 
TY  - CHAP
A1  - Akimbekov, Nuraly S.
A1  - Digel, Ilya
A1  - Razzaque, Mohammed S.
T1  - Role of vitamins in maintaining structure and function of intestinal microbiome
T2  - Comprehensive Gut Microbiota
N2  - The recent advances in microbiology have shed light on understanding the role of vitamins beyond the nutritional range. Vitamins are critical in contributing to healthy biodiversity and maintaining the proper function of gut microbiota. The sharing of vitamins among bacterial populations promotes stability in community composition and diversity; however, this balance becomes disturbed in various pathologies. Here, we overview and analyze the ability of different vitamins to selectively and specifically induce changes in the intestinal microbial community. Some schemes and regularities become visible, which may provide new insights and avenues for therapeutic management and functional optimization of the gut microbiota.
KW  - Vitamin A
KW  - Vitamin B
KW  - Thiamine
KW  - Riboflavin
KW  - Niacin
Y1  - 2022
SN  - 978-0-12-822036-8
U6  - https://doi.org/10.1016/B978-0-12-819265-8.00043-7
SP  - 320
EP  - 334
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Abbas, Karim
A1  - Balc, Nicolae
A1  - Bremen, Sebastian
A1  - Skupin, Marco
T1  - Crystallization and aging behavior of polyetheretherketone PEEK within rapid tooling and rubber molding
JF  - Journal of Manufacturing and Materials Processing
N2  - In times of short product life cycles, additive manufacturing and rapid tooling are important methods to make tool development and manufacturing more efficient. High-performance polymers are the key to mold production for prototypes and small series. However, the high temperatures during vulcanization injection molding cause thermal aging and can impair service life. The extent to which the thermal stress over the entire process chain stresses the material and whether it leads to irreversible material aging is evaluated. To this end, a mold made of PEEK is fabricated using fused filament fabrication and examined for its potential application. The mold is heated to 200 ◦C, filled with rubber, and cured. A differential scanning calorimetry analysis of each process step illustrates the crystallization behavior and first indicates the material resistance. It shows distinct cold crystallization regions at a build chamber temperature of 90 ◦C. At an ambient temperature above Tg, crystallization of 30% is achieved, and cold crystallization no longer occurs. Additional tensile tests show a decrease in tensile strength after ten days of thermal aging. The steady decrease in recrystallization temperature indicates degradation of the additives. However, the tensile tests reveal steady embrittlement of the material due to increasing crosslinking.
KW  - additive manufacturing
KW  - fused filament fabrication
KW  - crystallization
KW  - polyetheretherketone
KW  - rapid tooling
Y1  - 2022
U6  - https://doi.org/10.3390/jmmp6050093
SN  - 2504-4494
N1  - The article belongs to the Special Issue Advances in Injection Molding: Process, Materials and Applications
VL  - 6
IS  - 5
SP  - 1
EP  - 12
PB  - MDPI
CY  - Basel
ER  -